2015 IEEE Aerospace Conference
  • 1 Science and Aerospace Frontiers (Plenary Sessions)
  • 2 Space Missions, Systems and Architectures Steven Scott (NASA Goddard Space Flight Center) & Peter Kahn (Jet Propulsion Laboratory) & Marina Ruggieri (University of Roma "Tor Vergata")
    • 02.01 Deep Space, Earth and Discovery Missions Nick Chrissotimos (NASA - Goddard Space Flight Center) & James Graf (Jet Propulsion Laboratory)
      • 02.0101 ECOSTRESS End-to-end Radiometric Validation William Johnson (Jet Propulsion Laboratory), Renaud Goullioud (Jet Propulsion Laboratory) Presentation: William Johnson - Sunday, March 3th, 05:20 PM - Madison
        The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) will measure the temperature of plants from the space station. This information will be used to generate products such as evapotranspiration (ET) over an effective diurnal cycle to better understand how much water plants need and how they respond to stresses (i.e. lack of water, sun, nutrients). The radiometer onboard the ECOSTRESS payload provides five thermal infrared (TIR) spectral bands with approximately 70m pixels and a nearly 400km swath. It incorporates many new technologies such as a high-speed Mercury Cadmium Telluride (MCT) focal plane array (FPA), black silicon calibration targets, and a thermal suppression filter allowing shortwave infrared (SWIR) bandpass. This radiometer has two on-board blackbodies to maintain calibration every sweep of the scan mirror (1.4s). The system has undergone an end-to-end test in a thermal-vacuum (TVAC) chamber showing excellent pre-flight radiometric results. This performance is in part enabled by a newly developed, high-speed, low noise, readout electronics. The readout electronics converts all 32-analog channels to digital for onboard processing and downlink. Noise equivalent delta temperature (NEDT) measurements and brightness temperature (BT) retrievals are well within requirements. The optical modulation transfer function (OMTF) is also within specification. The sensor was launched on SpaceX CRS-15 along with Materials ISS Experiment Flight Facility (MISSE-FF) 2 and a Latching End Effector. ECOSTRESS is currently undergoing In-Orbit Checkout (IOC). This is where all systems as well as science/calibration data are checked and verified to be operational. ECOSTRESS uses a local WiFi that sends data from the payload to the ISS. Data packets are then downlinked to the Huntsville Operations Support Center (HOSC) and subsequently achieved in the science data system (SDS) servers. A series of calibration targets such as Lake Tahoe, Salton Sea and the Great Lakes will be used to verify the top of atmosphere radiometric integrity of the science data. Other geometrical targets such as the fields of California and large bridges around CONUS will be sued to verify the geolocation accuracy when compared with previous data from (Visible Infrared Imaging Radiometer Suite) VIIRS and ASTER.
      • 02.0102 The James Webb Space Telescope: Mission Overview and Status Matthew Greenhouse (NASA - Goddard Space Flight Center) Presentation: Matthew Greenhouse - Sunday, March 3th, 04:30 PM - Madison
        The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 m2 aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 um. The science instrument payload includes four passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 <  < 5.0m spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 <  < 29 m spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. Construction, integration and verification testing is underway in all areas of the program. The JWST is on schedule for launch during 2021.
      • 02.0103 Riders on the Storm: NASA InSight Lander and the 2018 Mars Global Dust Storm Michael Lisano (Jet Propulsion Laboratory) Presentation: Michael Lisano - Sunday, March 3th, 04:55 PM - Madison
        The author will discuss operational experiences from the InSight mission, addressing the Global Dust Storm that rose up a month after InSight launched and how that impacted in-flight final preparations for landing and operating on Mars. The talk also monitoring and managing energy resources during the first two months after InSight’s landing on Nov 26, 2018, describing some unique challenges of operating InSight in a tactical mode in a time-varying dust environment, during deployment of InSight’s science instruments onto the Martian surface.
      • 02.0104 IXPE Observatory Integrated Thermal, Power, and Attitude Mission Design Analysis William (Bill) Kalinowski (Ball Aerospace), William Deininger (Ball Aerospace) Presentation: William (Bill) Kalinowski - Sunday, March 3th, 09:25 PM - Madison
        This paper describes how the Imaging X-Ray Polarimetry Explorer (IXPE) mission design drives the power and thermal design of this low-Earth orbiting observatory. The observatory attitudes of the design reference mission observation sequence are presented with discussion on their relationship to the heater loads of the observatory. The paper also includes a brief discussion of potential optimizations and possible trades.
      • 02.0105 IXPE Mission System Concept and Development Status William Deininger (Ball Aerospace), William (Bill) Kalinowski (Ball Aerospace) Presentation: William Deininger - Sunday, March 3th, 09:00 PM - Madison
        The goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mission, a NASA Small Explorer (SMEX), is to expand understanding of high-energy astrophysical processes and sources, in support of NASA’s first science objective in Astrophysics: “Discover how the universe works.” Polarization uniquely probes astrophysical anisotropies—ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin—that are not otherwise measurable. Imaging enables the specific properties of extended X-ray sources to be differentiated. IXPE will conduct X-ray imaging polarimetry for multiple categories of cosmic X-ray sources such as neutron stars, stellar-mass black holes, supernova remnants and active galactic nuclei. The Observatory uses a single science operational mode capturing the X-ray data from the targets. The IXPE Observatory consists of spacecraft and payload modules built up in parallel to form the Observatory during system integration and test. The payload includes three X-ray telescopes each consisting of a polarization-sensitive, gas pixel X-ray detector, paired with its corresponding grazing incidence mirror module assembly (MMA). A deployable boom provides the correct separation (focal length) between the detector units (DU) and MMAs. These payload elements are supported by the IXPE spacecraft which is derived from the BCP-small spacecraft architecture. This paper summarizes the IXPE mission science objectives, describes the Observatory implementation concept including the payload and spacecraft elements and summarizes the mission status.
      • 02.0107 Moon Diver: A Discovery Mission Concept for Exploring a Lunar Pit to Investigate Flood Basalts Issa Nesnas (Jet Propulsion Laboratory) Presentation: Issa Nesnas - Sunday, March 3th, 09:50 PM - Madison
        Since Apollo, the Moon has served as a “keystone” for understanding planetary geological processes throughout the Solar System. The goal of Moon Diver mission concept is to return to Mare Tranquillitatis, taking advantage of the discovery of a natural pit cave entrance exposing a deep cross-section through both the lunar regolith as well as tens of meters of bedrock lava layers. Collecting information on the chemistry, mineralogy, and morphology of these intact bedrock layers would allow us to investigate where rocky crusts come from, how they are emplaced, and the process by which they are transformed into the regolith layer that we see from space. In doing so, the mission would combine the deep knowledge gained by Apollo with the unprecedented in situ access to secondary crust granted by the lunar mare pit to understand these fundamental processes on the Moon, and to use this knowledge as a keystone for understanding the same processes across the Solar System. Access to the record exposed in the wall of this pit is provided by two critical space technologies: pinpoint landing and extreme terrain mobility. Pinpoint landing is a closed-loop guidance and navigation capability that repeatedly matches visual features from a downward-facing camera to a priori acquired terrain maps. This body-relative navigation is then used with closed-loop control to guide the spacecraft toward its landing target, yielding a tight landing ellipse. Once on the surface, an extreme-terrain robotic explorer, called Axel, would egress from the lander and traverse tens of meters to the pit. Anchored to the lander, the two-wheeled rover would pay out its tether as it traverses toward the pit. The rover carries a surface preparation tool together with a suite of three instrument types: (a) a trio of high-resolution cameras (Mars 2020’s EECAMs) for acquiring context images of the near and far walls with the near-wall pair in a stereoscopic configuration, (b) an alpha-particle-X-ray spectrometer (MSL’s APXS) for elemental composition, and (c) a multi-spectral microscopic imager (MMI) that uses controlled lighting for minerology. The surface-preparation tool, the MMI and the APXS would be deployed from their instrument bays in one of the wheel wells. The rover would independently point each of its instruments at the same target of interest on the wall with millimeter-level repeatability. Confidence in the technologies of pinpoint landing and extreme-terrain access is based on helicopter testing of terrain-relative navigation and field testing of extreme terrain mobility respectively. The surface mission timeline is just shy of a lunar day (14 Earth days). Throughout its traverse, the rover would acquire multiple measurements of both regolith and mare layers. After descending to the bottom of the layers, the rover would reach a significant overhang. This void space may open into a large cave or lava tube, which could someday provide a protected location for a lunar base. For these reasons, lunar pits provide an exciting new target for lunar exploration.
      • 02.0110 Europa Clipper Mission: Preliminary Design Report Todd Bayer (NASA Jet Propulsion Lab), Maddalena Jackson (Jet Propulsion Laboratory) Presentation: Maddalena Jackson - Monday, March 4th, 04:30 PM - Jefferson
        This paper will describe the progress of the Europa Clipper Mission since January 2018, including maturation of the spacecraft, subsystem and instrument preliminary designs, issues and trades, and planning for the Verification & Validation phase.
      • 02.0111 Mission Concept for a Europa Lander Jennifer Dooley (Jet Propulsion Laboratory, California Institute of Technology) Presentation: Jennifer Dooley - Monday, March 4th, 04:55 PM - Jefferson
        A NASA HQ-directed study team led by JPL with partners including APL, MSFC, GSFC, LaRC and Sandia National Laboratory has recently presented an updated mission concept for a Europa Lander that would search for bio-signatures and signs of life in the near-subsurface of the Jovian moon. This paper will describe that mission architecture including science objectives, interplanetary and delivery trajectory, flight system, planetary protection architecture and mission phases. The mission would follow the Europa Multiple-Flyby Mission Clipper planned for launch in June of 2022, which would provide reconnaissance imagery and other data to the Lander for use in selecting a scientifically compelling site and certifying it for engineering safety. The Europa Lander concept accommodates the Model Payload identified by the Europa Lander Science Definition Team (SDT) and documented in the Europa Lander Study 2016 Report released in February of 2017. Since holding a Mission Concept Review (MCR) in June of 2017, HQ directed the study team to further explore the architectural trade space with a goal of reducing the mission cost. Based on the results of that study, in December of 2017 HQ directed the study team to focus on biosignature science and shift to a Direct-to-Earth communication architecture. The currently envisioned Europa Lander would launch on an SLS Block 1B as early as Fall of 2026 into a V-Earth-Mars-Gravity Assist (VEMGA) trajectory, arriving in the Jovian system as early as mid-2031. The baseline design of the integrated flight system includes a Carrier Stage, a Deorbit Vehicle composed of a Deorbit Stage consisting of a solid rocket motor (SRM), an MSL-like sky-crane Descent Stage, and a Lander which accommodates the instrument suite. The Lander would be powered by primary batteries over a 20+ day surface mission. The science goals envisioned by the SDT for biosignature science require three samples taken from a depth of 10 cm, a depth chosen to ensure minimal radiation processing of the potential biomarkers. Mission challenges include the large launch mass, unknown terrain topography, surface composition and materials properties, the high radiation environment, and complying with the stringent planetary protection requirements. The mission concept uses a strategy of early risk reduction and overlapping requirements to provide robustness to harsh and uncertain environments. Early risk reduction efforts are aimed at maturing technologies associated with the sampling system, the intelligent landing system, high specific energy batteries, low mass and power motor controllers, and a thermal sterilization system. Jennifer Dooley, Jet Propulsion Laboratory, California Institute of Technology The information presented about the Europa Lander mission concept is pre-decisional, and is provided for planning and discussion purposes only.
      • 02.0112 Exploring the Chemical Diversity of Comets, Asteroids, and Interstellar Dust at 1 AU. Mihaly Horanyi (University of Colorado, Boulder) Presentation: Mihaly Horanyi - Monday, March 4th, 05:20 PM - Jefferson
        The FOSSIL mission concept would comprehensively survey the compositional diversity of a broad range of bodies in our solar system and beyond, returning a powerful set of measurements to test the genetic relationships between the main reservoirs of primitive materials left over from planet formation. FOSSIL would be placed in an Earth-trailing orbit, carrying four state-of-the-art Dust Telescopes (DT) pointed anti-sunward to measure impacting dust particles’ mass, composition, charge, and velocity vector. This approach connects decades of ground- based radar measurements of the speeds and directions of meteors from various sources, lacking compositional information, with decades of laboratory work on meteorites’ compositions, similarly lacking dynamical information that would reveal their sources. FOSSIL is a low-risk mission concept that would survey the composition of the solar system’s primitive material at a cost far lower than sending probes to a representative sample of small bodies. FOSSIL would go beyond the in situ measurements from Giotto, Ulysses, Stardust, Rosetta, and Cassini, to enable a breakthrough in understanding how the fine dust from comets, asteroids, and interstellar space evolves in our solar system’s largest visible structure, the Zodiacal Cloud.
      • 02.0113 InSight: A Discovery Mission to Mars Tom Hoffman (Jet Propulsion Laboratory) Presentation: Tom Hoffman - Monday, March 4th, 09:00 PM - Jefferson
        Will discuss the results of the early operations of the InSight Mars Mission including Cruise, Entry Descent and Landing and initial surface operations
      • 02.0114 Mars Sample Return Lander Mission Concepts Brian Muirhead (Jet Propulsion Laboratory), Ashley Karp (Jet Propulsion Laboratory) Presentation: Brian Muirhead - Monday, March 4th, 09:25 PM - Jefferson
        This paper will provide an overview of current concepts and options for the architecture and design of a Mars Sample Retrieval Lander (SRL). Key mission objectives and the overall baseline mission design will be described, including the mission’s constraints and a notional timeline from launch to entry, through surface operations, to delivery of the samples to Mars orbit. The overall lander vehicle concepts will be described, including current options being evaluated. Key lander element options will be discussed, including the Mars Ascent Vehicle (MAV), Sample Fetch Rover (SFR), Orbiting Sample container (OS), and tube transfer robotics systems. Specific challenges and approaches for addressing those challenges will be discussed, including backward planetary protection.
    • 02.02 Future Space and Earth Science Missions Patricia Beauchamp (Jet Propulsion Laboratory) & Robert Gershman (JPL)
      • 02.0206 Beyond TRL 9: Achieving the Dream of Better, Faster, Cheaper through TRL10 Commercial Technologies Peter Lord (SSL), Dan Goebel (Jet Propulsion Laboratory), William Hart (NASA Jet Propulsion Laboratory), Steve Snyder (Jet Propulsion Laboratory), Benjamin Solish (Jet Propulsion Laboratory), Catherine Keys () Presentation: Peter Lord - Thursday, March 7th, 09:00 PM - Amphitheatre
        On its web site NASA defines Technology Readiness Level (TRL) 9 as: “Actual systems ’flight proven through successful mission operations”. It’s the gold standard for the development and implementation of new technologies on NASA spacecraft, and originates from the idea that technologies that have flown can be expected to fly successfully again. While the risks associated with developing a new technology and using it in space are considered by NASA and most of the space community to have been retired by a first flight, there is no guarantee of reliability or success the next time the technology is used in space. In a recent paper, Straub [1] proposed establishing a TRL 10 level that indicates “proven technology demonstrated through extended operations”. After extensive discussion on the need for this and the possible definition, he suggested that a TRL definition higher than 9 would be useful in recognizing and taking advantage of higher maturity space hardware. Multiple other papers have made the case that hardware that has flown successfully and essentially unchanged multiple times will certainly have higher reliability and lower implementation risk than single flight units. The Psyche mission provides a unique case for testing these arguments about higher maturity hardware and extending the TRL scale beyond TRL 9. NASA’s Psyche mission is procuring the majority of its spacecraft bus from SSL’s commercial communication product line, which features spacecraft components and technologies with tens to hundreds of successful flights. In many cases, multiple generations of this hardware have been matured based on lessons learned, which guarantees reliability greatly in excess of one-shot hardware. This paper takes another look at the development of the TRL scale, arguments for its extension, and its application to NASA missions in the light of the flight proven, highly reliable commercial hardware described in this paper. We propose two additional TRL levels adopting and refining prior efforts to define levels of hardware maturity beyond TRL 9. This allows NASA to recognize and utilize the benefits of more mature technologies to build better spacecraft that can reliably explore the solar system; better, faster and cheaper than ever before.
      • 02.0208 An On-Orbit CubeSat Centrifuge for Asteroid Science and Exploration Jekan Thangavelautham (University of Arizona), Stephen Schwartz () Presentation: Jekan Thangavelautham - Thursday, March 7th, 09:25 PM - Amphitheatre
        AOSAT+ Mission Concept will be presented. It would include an overview of the science objectives behind the mission, followed by plans for technical implementation. The presentation will then get into the spacecraft details including science instrument and mission concept of operations. The paper will conclude with summary of achievements to date and future work.
    • 02.03 System and Technologies for Landing on Planets, the Moon, Earth and Small Bodies Clara O'farrell (Jet Propulsion Laboratory) & Ian Clark (Jet Propulsion Laboratory)
      • 02.03 2.03 Keynote: The lost Mars Lander: What we think we know about the Mars Polar Lander Rob Manning Presentation: Rob Manning - - Madison
        At 3:20 PM EST on December 3, 1999, only minutes before Mars atmosphere entry, the Mars Polar Lander (MPL) turned off its radio right on schedule. MPL and its two DS-2 microprobes have never been seen nor heard from since. What happened to MPL? Given that the 2007 Mars Phoenix lander was based on MPL, the team was forced to revisit, re-analyze and retest nearly every design detail. In the process the team uncovered a dozen new and surprising failure modes that might have led to MPL’s demise. Fortunately the Phoenix team (and later the Mars InSight team) was able to mitigate all of them before launch. Due to their tireless efforts, Phoenix successfully landed near the north pole of Mars on May 25, 2008. This talk will describe these new failure modes and will summarize what we know and don’t know about MPL.
      • 02.0301 Semi-Active Damping System Characterization for Landing in Microgravity Mauro Massari (Politecnico Di Milano), Paolo Astori (Politecnico di Milano), Francesco Cavenago (Politecnico di Milano) Presentation: Francesco Cavenago - Monday, March 4th, 08:55 AM - Madison
        The landing of space probes in microgravity poses very challenging problems both from the dynamical and technological point of view. The main problem of designing a damping system for landing in microgravity is the high uncertainty associated with the feature of the soil (i.e. damping and stiffness coefficients), therefore a highly robust design relying only on passive system is not possible. In this work a new approach to increase the robustness of the damping system for landing in microgravity is proposed, coupling a passive granular shock absorber with a semi-active piezoelectric based friction damper which can modulate the applied braking force using fast piezoelectric actuator acting on a sort of brake pad. The proposed concept has been carefully modelled, identifying characteristic parameters of both the passive and active parts. In the case of the granular shock absorber, numerical discrete elements simulations have been validated conducting an experimental campaign in relevant conditions. Then the identified model of the semi-active damping system has been used to conduct an extensive sensitivity analysis of the performance achievable in a wide range of landing velocity and soil features.
      • 02.0305 Aero Maneuvering Dynamics and Control for Precision Landing on Titan Marco Quadrelli (Jet Propulsion Laboratory) Presentation: Aaron Schutte - Monday, March 4th, 09:20 AM - Madison
        Saturn’s moon Titan is the richest laboratory in the solar system for studying prebiotic chemistry, which makes studying its chemistry from the atmosphere to the surface one of the most important objectives in planetary science. The focus of our work is on technology development to substantially reduce Titan lander delivery error. We have developed and tested several dynamic models of the parafoil system descending in Titan’s atmosphere. These dynamic models include a progression from point mass models to rigid multibody models, including relative dynamics between canopy and payload. In these models, we have included wind models used for Titan simulation, and extrapolated wind gust models previously used for simulation in the Martian environment. We have also developed guidance and control techniques for autonomous parafoil turning in the adverse wind environment. Finally, and in order to improve the controller performance by reducing the uncertainty to environmental factors, we have also developed ways to estimate the Titan environmental parameters, i.e. the atmospheric density, and the wind magnitude, during the descent. A more complete and realistic simulation is being developed and tested in JPL’s Entry, Descent, and Landing Software framework.
      • 02.0308 Mars 2020 Entry, Descent, and Landing System Overview Adam Nelessen (Jet Propulsion Laboratory), Chloe Sackier (), Ian Clark (Jet Propulsion Laboratory), Paul Brugarolas (), Gregorio Villar (), Allen Chen (Jet Propulsion Laboratory), Aaron Stehura (Jet Propulsion Laboratory), Richard Otero (Georgia Institute of Technology), Erisa Stilley (), David Way (NASA - Langley Research Center), Karl Edquist (NASA - Langley Research Center), Swati Mohan (NASA Jet Propulsion Laboratory), Cj Giovingo (Jet Propulsion Laboratory), Mallory Lefland () Presentation: Adam Nelessen - Monday, March 4th, 09:45 AM - Madison
        This presentation will provide the latest status of the Mars 2020 Entry, Descent, and Landing (EDL) system. A brief overview of the Mars 2020 mission begins the talk, with a focus on mission elements that influence the EDL system design. Then, a recap of the Mars Science Laboratory (MSL) EDL system, from which Mars 2020 EDL draws significant heritage, will be provided. An overview of the lessons learned since the MSL will occur next, in which the improvements that have made the system more robust will be highlighted. Next, the presentation will describe the enhancements that have been made to this system. For example, the use of Terrain Relative Navigation enables the mission to safely target a landing ellipse that would have been considered too risky for previous missions due to terrain hazards. Finally, some of the noteworthy challenges that have faced the team in the development of the Mars 2020 EDL system will conclude the talk. The system development is proceeding well, and the team is on track to complete verification and validation of the EDL system in advance of launch in July of 2020.
      • 02.0309 Overview of the ASPIRE Project’s Supersonic Flight Tests of a Strengthened DGB Parachute Clara O'farrell (Jet Propulsion Laboratory), Bryan Sonneveldt (Jet Propulsion Laboratory), Chris Karlgaard (Analytical Mechanics Associates, Inc.), Ian Clark (Jet Propulsion Laboratory) Presentation: Clara O'farrell - Monday, March 4th, 10:10 AM - Madison
        The Advanced Supersonic Parachute Inflation Research Experiments (ASPIRE) project is aimed at developing and exercising a capability for testing supersonic parachutes at Mars-relevant conditions. The initial flights for ASPIRE were targeted as a risk-reduction activity for NASA's upcoming Mars2020 mission. For this effort, two candidate Disk-Gap-Band (DGB) parachute designs were tested at Mach number and dynamic pressure conditions relevant to Mars2020. The two parachutes under investigation were a build-to-print version of the DGB used by the Mars Science Laboratory and a strengthened version of this parachute that has the same geometry but differs in materials and construction. The first flight test (SR01) of the build-to-print parachute took place on October 4, 2017, followed by the first test of the strengthened parachute during flight SR02 on March 31, 2018. A second test of the strengthened parachute with a higher target load, SR03, took place on September 7, 2018. During the SR02 test, a Terrier-Black Brant sounding rocket delivered a payload containing the packed 21.5-m parachute, the deployment mortar, and the ASPIRE instrumentation suite to a peak altitude of 54.8~km. As the payload descended back towards the Atlantic Ocean the strengthened parachute was mortar-deployed at a Mach number of 1.97 and a dynamic pressure of 670 Pa, and produced a peak load of 55.8 klbf. During the SR03 flight, the strengthened parachute was deployed from an identical test platform at a Mach number of 1.85 and a dynamic pressure of 932 Pa, and produced a peak force of 67.4 klbf. This paper describes ASPIRE's two sounding rocket flight tests of the strengthened parachute: SR02 and SR03. It provides an overview of flight operations, test conditions, the data acquired during testing, the techniques used for post-flight reconstruction, and the reconstructed performance of the test vehicle and parachute system for each flight.
      • 02.0311 A Terminal Descent Radar for Landing and Proximity Operations Brian Pollard (Remote Sensing Solutions) Presentation: Brian Pollard - Monday, March 4th, 10:35 AM - Madison
        We will present the design and build status of the new RSS Terminal Descent Radar, a pencil-beam radar in support of planetary landing missions as well as proximity operations for spacecraft, aircraft, and other vehicles.
      • 02.0312 Energy and Mass Utilization during Drag-Modulated Plasma Aerocapture Charles Kelly (University of Washington), Justin Little (University of Washington) Presentation: Charles Kelly - Monday, March 4th, 11:00 AM - Madison
        Plasma aerocapture is an orbit insertion technique that replaces the rigid decelerator of a typical aerocapture system with a dipole plasma that generates drag through capture of atmospheric particles. The plasma slows a spacecraft from its hyperbolic fly-by trajectory into a closed elliptic orbit using less than a gram of fuel. Its size and density can be modulated by the magnetic field, allowing tight control over the drag force and potentially vast improvements in orbit-targeting accuracy. This paper details a control volume model of the plasma interacting with a hypersonic neutral atmosphere that simulates the aerocapture entry flow. Results show that the magnetic field strength has a strong effect on ingestion of the atmospheric flow, implying good modulation capability. Additionally, the plasma requires no input power from the spacecraft, using flow power alone and a small amount of fuel injection to remain ignited. Between 1% and 33% of the incident flow is captured by the plasma. These results offer insight into the physics of plasma-atmosphere interaction during plasma aerocapture that can be leveraged for future self-consistent orbit trajectory modeling.
      • 02.0314 Systems Engineering for ASPIRE: A Low-Cost, High Risk Parachute Test Project Ryan Webb (NASA Jet Propulsion Lab), Thomas Randolph (Jet Propulsion Laboratory), Aigneis Frey (Massachusetts Institute of Technology) Presentation: Ryan Webb - Monday, March 4th, 11:25 AM - Madison
        The Advanced Supersonic Parachute Inflation Research Experiment (ASPIRE) managed by NASA’s Jet Propulsion Laboratory (JPL) has developed a sounding rocket test architecture to test a strengthened parachute for JPL’s Mars 2020 Rover. Categorized as a sub-orbital sounding rocket mission, the program is more risk tolerant than a typical JPL flight mission; thus more leeway is allowed in tailoring institutional requirements. However, since ASPIRE is a risk reduction activity for Mars 2020, its test results are significant to JPL and directly impact decisions for a flagship planetary mission. This, combined with the wide scope and complexity of ASPIRE – which spans multiple NASA sites, and includes distinct flight, ground, launch vehicle, and mission systems – creates unique programmatic challenges. Furthermore, as a program composed of multiple test missions, it is possible to evaluate the effectiveness of the systems engineering approach between launches. As a result, the project has developed an adapted version of typical systems engineering functions such as verification and validation (V&V), resource management, risk management, engineering change requests, and lifecycle management. A set of project guidelines has been established to accommodate the small team size, low budget, and higher risk posture of the project while also maintaining the highest possible chance of mission success and quality of engineering data products. This talk describes ASPIRE’s unique approach to systems engineering functions, and evaluates successes and lessons learned.
    • 02.04 Access to Space and Emerging Mission Capabilities Eleni Sims (Aerospace Corporation) & David Callen (Tyvak Corporation)
      • 02.0401 Design and Development of RVSAT-1, a Student Nano-satellite with Biological Payload Kai Maitreya Hegde (R. V. College of Engineering), Abhilash C R (R V College of Engineering), Pramod Pavamana Kumar Kashyap (), Anirudh K (R V College of Engineering) Presentation: Kai Maitreya Hegde - -
        Many universities across India are coming up with low-cost Pico/Nano/Micro Satellites that have community based missions or payloads. Most of these are solely built by students who have no or very little experience in space technology. Students are driven by sheer motivation to build satellites and make exhaustible plans, especially in the ones which are carrying a biological experiment to space. RVSAT-1 is the first nano-satellite from India to carry a mass of microbes to space in a custom-designed apparatus. Microbes were carefully selected on the basis of their presence in human gastro-intestinal tract and a ground-based analysis was done beforehand. Systems engineering (SE) methodology is adopted while making such a robust satellite, way before from the time of initiation of fabrication. The satellite is of a 2U CubeSat standard design with 10 cm × 10 cm × 22.7 cm dimensions and an overall weight of 2.66kg. The satellite is capable to operate at a flexible orbital height since it has no observation payload. It houses a beacon system that is switched on at all times which posed a challenge while designing the electrical power subsystem. A payload chamber is also incorporated with two independent systems: the microbe characteristic measurement apparatus and a deorbiting system housing an electrodynamic tether-type mechanism. The satellite is expected to stay in orbit for 1 year to carry out the microbe growth and metabolism measurements and then undergoes a deorbit phase of 2 years. Tools like AGI STK were used to model the mission and FDIR (Fault Detection, Isolation and Recovery) obtained was applied to all the subsystems.
      • 02.0403 Multiple Asteroid Retrieval Mission from Lunar Orbital Platform-Gateway Using Reusable Spacecrafts Gustavo Gargioni (Virginia Tech), Marco Peterson (Virginia Tech), David Alexandre (Virginia Tech), Kevin Schroeder (Virginia Tech) Presentation: Gustavo Gargioni - Tuesday, March 5th, 08:30 AM - Gallatin
        Abstract—This paper describes the results of a study to find possible Near Earth Asteroids (NEA) capable of being captured using upcoming rocketry for the purposes of space-based mining, combining reusable rockets such as SpaceX’s Big Falcon Rocket (i.e. BFR) and refueling capabilities. This work introduces a relatively low-cost option with higher Delta V, ∆V , compared to non-reusable rockets, and an opportunity for NASA’s Lunar Orbital Platform-Gateway (LOP-G) for synergy with services, science, and technologies. In an effort to maximize the number of viable missions, the study focused on choosing a refueling orbit near LOP-G; thus, the Earth-Moon Lagrange points L1 and L2 were selected as possible choices for this paper. The resulting simulations of a Cislunar infrastructure orbiting in Lagrange points highlight differences in orbital options. Indeed, the optimal option is balanced between a Near Rectilinear Halo Orbit (NRHO) in L1 and a NRHO in L2. The decision for optimal positioning of any Gateway Station is dependent on the type of mission allocated to the Cislunar station. However, both options seem promising, not only for asteroid extraction and mining but also for crewed and cargo missions. In a worst case scenario, an operation of 3 decades starting in 2030 retrieving 33 asteroids, or 1.1 per year, comprising up to 2,581 tons in minerals. The work culminated in developing a data mining on-line tool that searches the entire Near Earth Asteroids (NEA) close approach database from JPL and the small body database from NASA. Using a fleet of 10 BFRs over 30 years may provide a higher long-term success for a business case than any other investment on Earth.
      • 02.0404 SPARC – 1: A New, Improved Modular 6U Spacecraft Craig Kief (COSMIAC at UNM), James Lyke (Space Vehicles Directorate), Don Fronterhouse (PnP Innovations, Inc), Christian Peters (Air Force Research Laboratory), Matthew Hannon (COSIMAC University of New Mexico) Presentation: James Lyke - Tuesday, March 5th, 08:55 AM - Gallatin
        SPARC-1 (Space Plug-and-play Architecture Research Cubesat-1) is the first joint US/Sweden military research nanosatellite (6U cubesat), representing culmination of a research activity spanning more than a decade. The spacecraft design encompasses a blending of technologies and components developed by both countries, with primary payloads of direct interest to each nation. The US payload, referred to as an Agile Space Radio (ASR) is an on-orbit reconfigurable transceiver, intended to support live experimentation with different waveforms and protocols useful to communications missions. The Swedish payload is a visible camera optimized for the study of space situation awareness (SSA) concepts. At the time of this writing, the spacecraft development, assembly, integration, and testing has been successfully completed, and SPARC-1 is expected to launch in 2019.
      • 02.0405 Design and Experimental Validation of a Martian Water Extraction System Daniel Mc Gann (Northeastern University), Emilia Kelly (), Ben Zinser (Northeastern University), Elisa Danthinne (), Patrick Moore (), Andrew Panasyuk (Desktop Metal), Taskin Padir () Presentation: Ben Zinser - Tuesday, March 5th, 09:20 AM - Gallatin
        This paper discusses the design and realization of a robotic water extraction system used to harvest subsurface ice from a simulated Martian environment. The Mars Reconnaissance Orbiter has discovered ice buried approximately 1-2~m below the surface at the mid-latitudes of Mars. Access to this vital resource could greatly contribute to the success of a human mission to Mars. Our research and development effort into the in-situ procurement of water on Mars was guided by the 2018 NASA Revolutionary Aerospace System Concepts Academic Linkages (RASC-AL) Mars Ice Challenge. The focus of the challenge was to validate design concepts that maximize water collected from a simulated Martian test-bed using a robotic system. The steering committee provided the team with a design framework including functional, operational, and physical requirements. For this challenge, the team developed the Planetary Articulating Water Extraction System (PAWES). PAWES uses an auger based drilling system in combination with an articulating water extraction tool to collect water from subsurface ice deposits. In this paper, we present potential solutions to ice extraction on Mars, an overview of the PAWES system, and experimental results of prototype testing in terrestrial conditions. Additionally, we will discuss lessons learned from the implementation and validation of PAWES to guide further development of Martian water extraction systems.
      • 02.0407 Air-Launched Low-SWaP Space-Capable Sounding Rocket Anjali Roychowdhury (Stanford University), Thomas White (Stanford Universtiy), Andrew Lesh (Stanford University), Tim Vrakas (), Michael Arcidiacono (), Skye Vandeleest (Stanford University), Rayan Sud (Stanford University), Kadin Hendricks (Stanford University), Sasha Maldonado (Stanford University), Daniel Shorr (Stanford University), Kartik Chandra (Stanford University), Victoria Thompson (Stanford University), Ben Goldstein (Stanford University), Kai Marshland () Presentation: Anjali Roychowdhury - Tuesday, March 5th, 09:45 AM - Gallatin
        The Stanford Student Space Initiative (SSI) is building a balloon-launched rocket in the hope of being the first civilian collegiate team to launch something to space. In the process, we've created a low Size-Weight-and-Power (SWaP) system to cheaply and effectively launch payloads to sub-orbital trajectories. We've explored many interesting challenges, such as spin-stability in the lack of an atmosphere, ignition in vacuum, custom student-researched-and-developed (SRAD) radios to meet our unique specifications, and more. These topics will be discussed at the presentation of our project.
      • 02.0410 Enhanced Feasibility Assessment of Payload Adapters for NASA’s Space Launch System David Smith (Victory Solutions), Jon Holladay (NASA), Terry Sanders (Jacobs Technology) Presentation: David Smith - Tuesday, March 5th, 10:10 AM - Gallatin
        Efficient development iteration of Space Launch System Payload Adapter capabilities using Model Based System Engineering techniques.
    • 02.05 Robotic Mobility and Sample Acquisition Systems Richard Volpe (Jet Propulsion Laboratory)
      • 02.0502 Virtual Model Control for Planetary Hexapod Robot Walking on Rough Terrain Francesco Cavenago (Politecnico di Milano), Marco Canafoglia (Politecnico Di Milano), Mauro Massari (Politecnico Di Milano) Presentation: Francesco Cavenago - Tuesday, March 5th, 10:10 AM - Jefferson
        Virtual Model Control (VMC) is proposed to address the gait control problem of a space hexapod robot. In the VMC framework, a series of virtual elements, like springs and dampers, are attached to specific points on the body to generate desired joint torques. Especially, the control of the gait is divided into two phases: stance phase and swing phase. In the former, the VMC is exploited to compute the torques for the standing legs required to control the body height and attitude. The virtual elements are attached to the hips in such a way to govern each degree of freedom. On the other hand, in the latter phase, the VMC provides the control actions for the swing legs to follow a desired trajectory. In this case, the springs and dampers are attached between the foot of the leg and a point on the desired trajectory. The legs alternate these two modes cyclically and this switch is commanded by a state machine. In this work, three possible gaits are considered: tripod gait, wave gait and stick gait. The strength of the VMC and its suitability for space applications lie on its intuitiveness, robustness and computational efficiency. The effectiveness and performance of the proposed approach are assessed through numerical simulations considering different terrain roughness.
      • 02.0503 PlanetVac Xodiac: Lander Foot Pad Integrated Planetary Sampling System Justin Spring (Honeybee Robotics Spacecraft Mechanisms Corporation), Kris Zacny (Honeybee Robotics Spacecraft Mechanisms Corporation), Bruce Betts (The Planetary Society), Philip Chu (Honeybee Robotics), Steven Ford (Honeybee Robotics Spacecraft Mechanisms Corporation), Kathryn Luczek (Honeybee Robotics Spacecraft Mechanisms Corporation), Andrew Peekema (), Nick Traeden (Honeybee Robotics Spacecraft Mechanisms Corporation), Reuben Garcia (Masten Space Systems), Ian Heidenberger () Presentation: Justin Spring - Wednesday, March 6th, 10:10 AM - Jefferson
        The PlanetVac pneumatic sampling system is a simple yet effective way to collect samples from extraterrestrial bodies involving no moving parts. PlanetVac was integrated onto the foot of the Masten Xodiac rocket and tested in a flight environment in the Mojave desert. This paper outlines the development and testing of PlanetVac Xodiac.
      • 02.0504 Balloon-based Concept Vehicle for Extreme Terrain Mobility Hari Nayar (NASA/JPL), Michael Hans (JPL), Morgan Cable (NASA Jet Propulsion Laboratory), Mike Pauken (Jet Propulsion Laboratory) Presentation: Michael Hans - Tuesday, March 5th, 10:35 AM - Jefferson
        Surface mobility over extreme terrains on planetary bodies will enable access to high-value science targets, for example, exploration of dunes, lake shorelines and putative cryovolcanos on Titan and Recurring Slope Lineae (RSL) on Mars. The steepest slope attempted by any rover on Mars to date is 32°, and slippage was so great in this case that the course was abandoned. Slopes greater than 20° are considered too steep for rover traversal. In this paper, we describe a new concept for surface mobility on planetary bodies with atmospheres. BALLET (BALloon Locomotion for Extreme Terrain) is a balloon mobility concept with 6 evenly-distributed suspended payload modules each serving as a foot for locomotion over currently inaccessible rugged terrain on Mars and Titan. Each foot is suspended by 3 cables from the balloon to control its placement on the ground. Only 1 foot is raised at a time while the remaining feet keep the balloon anchored to the surface. This reduces the buoyancy required and consequently the size compared to a conventional balloon system. To locomote over the surface, each foot is moved in sequence by controlling the three cable lengths. Images from cameras on the balloon are used to map and locate foot placement and for navigation. The platform is inherently highly stable because its center of gravity is at ground level enabling operation on rugged terrain. BALLET achieves its benefits through several innovations: 1) use of a balloon for buoyancy and as a platform for locomotion, 2) limbs composed of cables in tension with significantly less mass than legs composed of links in compression, 3) partitioning the payload into six modular elements and lifting of only one at a time to significantly reduce the needed buoyancy and balloon size, 4) use of the remaining feet on the ground as anchors to restrain BALLET to the desired position, and 5) placement of the payload in the feet keeping the center of gravity very low and the platform highly stable. Physics requirements for the design of BALLET are: 1) the balloon buoyancy force must exceed the weight of one payload foot and, 2) the balloon buoyancy force must be less than the weight of two feet to minimize balloon size. These requirements enable BALLET to lift only one foot at a time while the remaining feet anchor it to the surface. For a nominal design, the buoyancy force of the balloon is set equal to the weight of 1½ feet to accommodate variations in buoyancy due to temperature variations and wind drag forces. The CG will be near the ground and centered within the feet locations. The CG height will increase slightly when a foot is raised but still maintain high stability. The balloon’s center of buoyancy will be within the balloon volume and above the feet. While the physics of BALLET will apply on Venus, the environmental conditions and available component technology limit our consideration to Mars and Titan.
      • 02.0505 Hopping for Low-cost Surface Mobility on Small Bodies: Lessons from past Missions Nikolas Romer (Occidental College), Arthur Chmielewski (Jet Propulsion Laboratory), Nathan Barba (Jet Propulsion Laboratory), Nathan Fulmer (La Cañada High School) Presentation: Nikolas Romer - Tuesday, March 5th, 09:20 AM - Jefferson
        There is great interest in missions to small bodies in our solar system such as asteroids, comets, Centaurs, dwarf planets, and moons. A key aspect of these bodies that makes them interesting is their varying morphologies over (and under) their surfaces. To characterize these bodies with in-situ exploration, a surface landing architecture is necessary that allows for the study of multiple diverse areas. Current stationary surface landers have only a short range, limited to capabilities of their on-board instruments and robotic arms. Surface rovers, while more mobile, are inherently more complex than landers and incur high costs both in development and operations. A surface lander capable of performing multiple hops could not only lower the cost of this mobility significantly, but also allow for the characterization of even more diverse areas than a rover. While a rover can cover tens of kilometers over the course of its lifetime, a hopper could potentially perform multiple hops of that same distance. While multiple mission concepts have been proposed (CHOPPER, Mars Geyser Hopper, GRUNT), and some have even flown (MINERVA-II, NEAR Shoemaker, Philae), the only mission to execute a planned hop on the surface of another body is the lunar lander, Surveyor 6. Performed in November of 1967, the results of this three-meter hop experiment contain lessons that will aid the development of future hopping mission concepts. This paper will first summarize previous hop attempts – both intentional and unintentional – and proposed concepts for future hopping spacecraft. A more in-depth study of the Surveyor 6 mission will be included, and lessons learned from the study will be applied to other small bodies. Analysis of ballistic, Surveyor 6-like hops, are performed for a diverse catalogue of small bodies including dwarf planet Ceres, comet 67P, and the moon Triton. Feasibilities of hops on each body are then evaluated based on distance and ∆-V, among other considerations. The utility of another style of hop, the “jump-and-wait” method, is also examined for the same bodies and compared to the Surveyor style hop results. The paper will conclude with a summary of the applicability of various types of hops for a variety of small bodies.
      • 02.0506 Towards Articulated Mobility and Efficient Docking for the DuAxel Tethered Robot System Patrick Mc Garey (NASA Jet Propulsion Lab), Issa Nesnas (Jet Propulsion Laboratory) Presentation: Patrick Mc Garey - Tuesday, March 5th, 08:30 AM - Jefferson
        This talk details a novel design update to the DuAxel system, which enhances mobility and docking efficiency for a pair extreme terrain, tethered Axel rovers. The improved system uses an articulated docking mechanism that enables sit/stand mobility. In the sit configuration, one Axel can undock and explore while the backup Axel and central module serve as a temporary anchor. In its stand configuration, each Axel can pivot independently for the purpose of articulated steering. We show a kinematic model for DuAxel that accomplishes four different steering modes in addition to sit/stand functionality. We evaluate the proposed design and kinematic model in a series of outdoor experiments performed with a recently completed DuAxel prototype. The results demonstrate that the proposed system improves upon the prior DuAxel design and offers new functionality by incorporating just two additional actuators.
      • 02.0515 Initial Study of Multirobot Adaptive Navigation for Exploring Environmental Vector Fields Christopher Kitts (Santa Clara University) Presentation: Michael Swartwout - Tuesday, March 5th, 09:45 AM - Jefferson
        Adaptive navigation is the process of modifying a vehicle’s direction or path based on measurements taken while moving. Significant work in this area has been performed for scalar fields, in which a single measurement such as the temperature or the concentration level of a pollutant is associated with every point in the field; scalar field capabilities that have been developed include control strategies for finding local extrema, moving along contour lines, and navigating along ridges/trenches within a field. One can imagine the ability to perform similar maneuvers in flow fields, in which a vector quantity such as fluid/airflow is associated with each point in the field. In such a field, various applications could benefit from the ability to navigate to/along sources and sinks, vortices, stagnation points, and so on. In this paper, we propose several simple control strategies for a multirobot formation to navigate to/along such features. Each technique is explained, and we describe how each can be implemented in a multilayer control system in which adaptive navigation commands are issued to a multirobot formation control layer, which in turn issues directives to individual robots. Simple simulation case studies are used to demonstrate the behavior of each control technique. We also describe initial work in preparing for experimental demonstration of these techniques using two multirobot systems: a simple indoor testbed consisting of small omniwheeled rovers, and a cluster of automated boats todemonstratethetechniquesinthefield. Finally, wereview ongoing and future work in adaptive navigation, to include both scalar and vector field applications as well as extensions to three dimensional fields.
      • 02.0516 Estimating Wheel Slip of a Planetary Rover via Unsupervised Machine Learning Justin Kruger (Stanford University), Arno Rogg (NASA - Ames Research Center), Ramon Gonzalez (robonity) Presentation: Justin Kruger - Tuesday, March 5th, 08:55 AM - Jefferson
        Planetary exploration rovers often encounter imperfect traction and wheel slip, which negatively impacts navigation and in the worst case can result in permanent immobilization. Recent studies have applied machine learning to estimate rover wheel slip, which this paper extends via the implementation of three unsupervised learning algorithms: self-organizing maps, k-means clustering, and autoencoding. Unsupervised learning is preferred since labelled training data may be risky or time-consuming to obtain on site; each algorithm classifies the rover’s current slip state into one of several discrete categories. Proprioceptive sensors are used to avoid added complexity and prevent a reliance on visual odometry. The algorithms are validated using sensor data from a planetary rover driving on a sandy incline, and performance is evaluated for different velocities, sensor inputs, slip classes, algorithm parameters, and data filters. Self-organizing maps (SOM) demonstrate the best slip classification accuracy, achieving 97% immobilization detection in the ideal two-class case. At rover-like speeds of 0.10 m/s, 88% accuracy is demonstrated for three classes. For ten slip classes, 71% accuracy is obtainable. Compared to SOM, k-means loses 5-30% accuracy and autoencoders lose 2-10% accuracy. SOM is most computationally intensive while k-means is least. An analysis of significant parameters for algorithm tuning displays accuracy benefits of up to 25%, and mis-classifications can be further reduced by modifying class boundaries. The algorithms are generic and can be trained for different terrain, environment or vehicle parameters, and although some labelled data is needed to directly associate unsupervised clusters with slip classes, it is significantly less than what a fully-supervised algorithm requires. Unsupervised learning is thus considered promising for robust real-time rover slip estimation.
      • 02.0517 Cryobotics: Extreme Environment Testing at Cryogenic Temperatures Drew Smith (NASA - Kennedy Space Center), Andrew Nick (), Jason Schuler (EASI) Presentation: Drew Smith - Wednesday, March 6th, 08:30 AM - Jefferson
        Initial performance testing of grease-less strain wave gears in extreme cold environments.
      • 02.0518 Analysis of the Space Robotics Challenge Tasks: From Simulation to Hardware Implementation Murphy Wonsick (Northeastern University), Velin Dimitrov (Northeastern University), Taskin Padir () Presentation: Murphy Wonsick - Tuesday, March 5th, 11:25 AM - Jefferson
        Approaches and methods developed for the Space Robotics Challenge (SRC), a simulation based NASA Centennial Challenge requiring teams to integrate mobility, manipulation, and perception, are not well grounded with respect to the limitations and challenges posed by real robots. We describe the hardware and software details behind the Valkyrie humanoid robot designed by NASA's Johnson Space Center, originally for the DARPA Robotics Challenge (DRC). We present our results on implementing behaviors, which include: valve/wheel turning, grasping, walking, stair climbing, and arm workspace movements, necessary to complete the SRC tasks on both the physical Valkyrie and a simulated Valkyrie. This paper is aimed at providing a collection of practical knowledge and lessons learned relevant to researchers without access to a full-size humanoid robot and other individuals who focus on future development of new humanoid robot platforms for space exploration. This knowledge if incorporated early in new efforts and developments will save time and effort to adapt approaches successful in simulation to real humanoid robot hardware.
      • 02.0520 Sampling Tool Concepts for Enceladus Lander In-situ Analysis Mircea Badescu (Jet Propulsion Laboratory), Paul Backes (Jet Propulsion Laboratory), Scott Moreland (Jet Propulsion Laboratory), Alex Brinkman (Jet Propulsion Laboratory), Dario Riccobono (Politecnico di Torino), Noel Csomay Shanklin (Georgia Institute of Technology), Samuel Ubellacker (Jet Propulsion Laboratory) Presentation: Mircea Badescu - Wednesday, March 6th, 09:20 AM - Jefferson
        A potential future in-situ lander mission to the surface of Enceladus could be the lowest cost mission to determine if life exists beyond Earth since material from the subsurface ocean, where the presence of hydrothermal activity has been strongly suggested by the Cassini mission, is available on its surface after being ejected by plumes and then settling on the surface. In addition, the low radiation environment of Enceladus would not significantly alter the chemical makeup of samples recently deposited on the surface. A study was conducted to explore various sampling devices that could be used by an in-situ lander mission to provide 1cc to 5cc volume samples to instruments. In addition to temperature and vacuum environmental conditions, the low surface gravity of Enceladus (1% of Earth gravity) represents a new challenge for surface sampling that is not met by sampling systems developed for microgravity (e.g., comets and asteroids) or higher gravity (e.g., Europa 13%g, Moon 16%g, or Mars 38%g) environments. It is desired to acquire surface plume material that has accumulated in the top 1cm to ensure acquisition of the least processed material. Several sampling devices were developed or adapted and then tested in simulated conditions that resemble the Enceladus surface properties. These devices and test results are presented in this paper.
      • 02.0521 Autonomous Mars ISRU Robotic Excavation: Characteristics and Performance Targets Hari Nayar (NASA/JPL), Brian Wilcox (Jet Propulsion Laboratory), A Howe (NASA Jet Propulsion Lab) Presentation: A Howe - Wednesday, March 6th, 10:35 AM - Jefferson
        Characteristic hardware concepts and performance targets are described for a potential robotic excavation system that can operate and robotically maintain itself without regular human intervention. In-Situ Resource Utilization (ISRU) is the exploitation of available resources at the site of a landed spacecraft on the surface of another planetary body. This can include harvesting of atmosphere, regolith, or rock for direct use (e.g. as radiation or micrometeorite shielding) or for separation/purification (e.g. for propellant production). The objective of this study is to try to identify a potential ISRU architecture, specifically for extracting water from hydrated minerals identified from orbital multispectral imaging on Mars, which can be implemented in an affordable way. By its nature this architecture must incorporate not only all the conventional excavate / scoop / haul / dump / process functions of a terrestrial mining operation on Earth, but also the sorts of maintenance and repair capabilities which any terrestrial mining operation would require in order to stay operational for an extended duration. The early concepts described in this study are intended for Mars, but also can be adaptable to lunar and other solar system planetary bodies.
      • 02.0522 Int-Ball: Crew-supportive Autonomous Mobile Camera Robot on ISS / JEM Shinji Mitani (Japan Aerospace Exploration Agency), Masayuki Goto (JAXA), Ryo Konomura (), Yasushi Shoji (Space Cubics, LLC.), Keiji Hagiwara (MEISEI ELECTRIC CO., LTD.), Shuhei Shigeto (Japan Aerospace Exploration Agency), Nobutaka Tanishima (Japan Aerospace Exploration Agency) Presentation: Shinji Mitani - Tuesday, March 5th, 11:00 AM - Jefferson
        This paper describes the development of an autonomous mobile camera robot that autonomously moves inside the JEM pressurization section and shoots image and video of the object, and the result of the initial checkout on orbit. The JEM Internal Ball Camera (called Int-Ball) is developed to eventually reduce the crew time resource related to the regularly consumed photo shooting to zero. This realization expects that about 10 % of the total crew resources are saved. As background, JEM ship fixed-point cameras are often used for crew task support in the JEM pressurization section. However, since the blind spots are large, for the ground control side to grasp the detailed situation of the work object remotely, it is necessary to rely on close-up photography with the hand-held camera. Also, when a crew sets up the camera and the object by oneself, it is difficult to adjust the angle of view and the focus. To improve the efficiency of such a shooting task, it is considered that realization of the camera which autonomously moves and can be fixed in a free space is useful. The Int-Ball is developed as a practical equipment which supports full-scale crew support, and the goal is to build environment of joint task of human and robot. If realized, crew time for ISS / JEM use can be used more effectively. In developing the Int-Ball, civilian technologies such as COTS parts and 3D printing technology are utilized to shorten development period and lower cost. The appearance of the Int-Ball is a spherical shape having a diameter of 150 mm or less not to disturb the work such as getting into the sight of the crew, and to consider the safety and the portability. Wireless network cameras providing real-time video downlink and still image acquisition service are capable of continuous shooting with resolution of 1280 x 720 pixels or more for 80 minutes or more duration. The main battery can be charged with USB bus power. When command from the ground control center is received, it moves autonomously to the target position. By applying the image navigation camera system (called Phenox, the drone technology) which performs onboard self-position estimation by using a polyhedral-shaped marker, it is possible to estimate relative 6 degrees of freedom under zero gravity environment. The camera robot control system combines the Phenox's self-position estimate value and MEMS inertial sensor information to realize 6-degree-of-freedom space movement by 12 small-sized axial flow fans and to realize image stabilized attitude control by 3-axis reaction wheels. The control system follows the concept of the flight control software of a small satellite and has a failure detection function, and a redundancy function for one failure. The Int-Ball was launched as payload of Dragon spacecraft by SpaceX Falcon 9 on June 3, 2017. First flight control demonstration was successfully conducted in JEM pressurization section. This paper also describes the initial checkout result.
      • 02.0523 Application of Pneumatics in Delivering Samples to Instruments on Planetary Missions Kris Zacny (Honeybee Robotics Spacecraft Mechanisms Corporation), Ralph Lorenz (Johns Hopkins University/Applied Physics Laboratory), Fredrik Rehnmark (Honeybee Robotics), John Costa (Honeybee Robotics Spacecraft Mechanisms Corporation), Joseph Sparta (Honeybee Robotics Spacecraft Mechanisms Corporation), Vishnu Sanigepalli (Honeybee Robotics Spacecraft Mechanisms Corporation), Zach Mank (Honeybee Robotics Spacecraft Mechanisms Corporation), Bernice Yen (Honeybee Robotics Spacecraft Mechanisms Corporation), David Yu (Honeybee Robotics Spacecraft Mechanisms Corporation), Jameil Bailey (Honeybee Robotics), Dean Bergman (Honeybee Robotics), William Hovik (Honeybee Robotics Spacecraft Mechanisms Corporation) Presentation: Fredrik Rehnmark - Wednesday, March 6th, 09:45 AM - Jefferson
        Traditional sample acquisition, transfer and capture approaches rely on mechanical methods (e.g. drill or a scoop) to acquire a sample, mechanical methods (e.g. robotic arm) to transfer the sample and gravity to capture the sample inside an instrument or a sample return container. This approach has some limitations: because of reliance on gravity, it is only suited to materials with no or little cohesion. Because of the sample transfer requiring mechanical system, the instrument or sample return container need to be easily accessible. Pneumatic based systems solve these problems because the pneumatic force can exceed the gravitational force and the sample delivery tubing can be routed around other spacecraft elements, making instrument or sample return container placement irrelevant to the sampling system. This paper presents background to pneumatic system applied to planetary missions and provides examples how this could be accomplished on planetary bodies with significant atmosphere (Venus and Titan) and on airless bodies (the Moon, Europa, Ceres).
      • 02.0524 Modeling of Cryobot Melting Rates in Cryogenic Ice Wayne Zimmerman (NASA Jet Propulsion Lab) Presentation: Wayne Zimmerman - Wednesday, March 6th, 08:55 AM - Jefferson
        The presentation will cover a brief history of ice probe modeling followed by more recent and detailed ice probe/penetration modeling results along with some actual validation lab tests.
    • 02.06 Future Missions & Enabling Technologies for In Situ Exploration, Sample Returns Patricia Beauchamp (Jet Propulsion Laboratory)
      • 02.0601 In-Situ Science Instruments in a Radioisotope Power System Environment Brian Bairstow (Jet Propulsion Laboratory), William Smythe (Jet Propulsion Laboratory), Alex Austin (Jet Propulsion Laboratory), Young Lee (Jet Propulsion Laboratory) Presentation: Brian Bairstow - Thursday, March 7th, 08:30 AM - Jefferson
        Radioisotope Power Systems (RPS) have enabled or enhanced many historic and current space missions. Concepts for future missions that could be powered by RPS include in-situ missions to the atmospheres, surfaces, and interiors of Europa, Titan, and other destinations. Such mission concepts are often tightly constrained on mass and volume, while still needing to support the instrument packages necessary to carry out ambitious science investigations, such as the search for signs of life. The physical proximity of RPS to payloads and to the in-situ environment has the potential to impact science instruments and science measurements. Radiation, thermal, vibration, electromagnetic interference (EMI), and magnetic fields impacts must all be considered carefully. This paper looks at existing and potential future RPS designs that could support in-situ missions, and discusses possible interactions with in-situ instruments, including those under development to open up new avenues of scientific discovery. In-situ operations have additional complications compared to in-space operations, including unique environments, and packaging and form factor requirements that drive spacecraft designs. Radiation, EMI, and magnetic fields from RPS could be an order of magnitude higher than for orbital spacecraft, if the RPS must be packaged within the element instead of mounted externally. Waste heat from RPS could cause changes to the local environment around the spacecraft, particularly in an atmospheric or subsurface environment. Vibrations produced by potential future dynamic RPS could interfere with seismic measurements. In addition, in-situ investigations can require different instrument technologies and measurement approaches. Many of these instrument types have not yet flown and require additional development to make them flight capable in the small volumes available for payloads. These developments will have implications for the instruments and their interactions with the RPS environment. Furthermore, all this is complicated by the fact that in-situ mission concepts can vary wildly from one another. Balloon elements have very different requirements compared to melt probes and submarines. Mission designers must consider these characteristics along with RPS and instrument accommodations.
      • 02.0602 Flight-Experiment Validation of the Dynamic Capabilities of a Flux-Pinned Docking Interface Frances Zhu (Cornell University), Mason Peck (Cornell University), Mitchell Dominguez (Cornell University), Laura Jones Wilson (Jet Propulsion Laboratory) Presentation: Frances Zhu - Thursday, March 7th, 08:55 AM - Jefferson
        The presentation will review the system characterization results from the microgravity experiment campaign, amplified by videos taken from said flight.
      • 02.0603 Genetic Algorithms for Autonomous, Learned Robotic Exploration in Extreme, Unknown Environments Frances Zhu (Cornell University), David Elliott (Cornell University), Zhidi Yang (), Haoyuan Zheng (Cornell University) Presentation: Frances Zhu - Thursday, March 7th, 09:20 AM - Jefferson
        The presentation will be a more graphical description of the paper, with video demonstrations and visual aids.
      • 02.0604 Area-of-Effect Softbots (AoES) for Asteroid Proximity Operations Jay Mc Mahon (University of Colorado Boulder), Kenshiro Oguri (University of Colorado Boulder), Shane Mitchell (University of Colorado Boulder), Donald Kuettel (), Nicholas Kellaris (University of Colorado Boulder), Christoph Keplinger (), Benjamin Bercovici (University of Colorado, Boulder) Presentation: Jay Mc Mahon - Thursday, March 7th, 09:45 AM - Jefferson
        An overview of the design of Area-of-Effect Softbots (AoES) will be presented. AoES are designed to operate on and interact with the surface of small asteroids for ISRU.
      • 02.0607 A Spring Propelled Extreme Environment Robot for Off-World Cave Exploration Steven Morad (The University of Arizona), Thomas Dailey (University of Arizona), Leonard Vance (University of Arizona), Jekan Thangavelautham (University of Arizona) Presentation: Steven Morad - Thursday, March 7th, 10:10 AM - Jefferson
        Pits on the Moon and Mars are mysterious geological formations that have yet to be explored. These geological formations can provide protection from harsh diurnal temperature variations, ionizing radiation, and meteorite impacts. Some have proposed that these underground formations are well-suited as human outposts. The Martian pits may harbor remnants of past life. Unfortunately, these geological formations have been off-limits to conventional wheeled rovers and lander systems due to their collapsed ceiling or "skylight" entrances. In this paper, a new low-cost method to explore these pits is presented using the Spring Propelled Extreme Environment Robot (SPEER). The SPEER consists of a launch system that flings disposable spherical microbots through skylights into the pits. The microbots are low-cost disposable spheres with an array of adapted COTS sensors and a solid rocket motor for soft landing. By moving most control authority to the launcher, the microbots become very simple and lightweight. We present a preliminary design of the microbots that can be built today using commercial components for under 500 USD. The microbots have a total mass of 1 kg, with more than 750 g available for a science instrument. In this paper, we present the design, dynamics and control, and operation of these microbots. This is followed by initial feasibility studies of the SPEER system by simulating exploration of a known Lunar pit in Mare Tranquillitatis.
      • 02.0608 A Flux Pinning Concept for On-orbit Capture and Orientation of an MSR Orbiting Sample Container Paulo Younse (Jet Propulsion Laboratory) Presentation: Paulo Younse - Thursday, March 7th, 10:35 AM - Jefferson
        Concepts for on-orbit capture and orientation of a Mars orbiting sample container (OS) using flux pinning were developed as candidate technologies for potential Mars Sample Return (MSR). The systems consist of a set of type-II superconductors field cooled below their critical temperature using a cryocooler, and operate on an orbiting sample container with a series of permanent magnets spaced around the exterior, along with an integrated layer of shielding to preserve the magnetic properties of the returned samples. Benefits of the approaches include passive, non-contact capture and orientation, as well as a reduction in the number of actuators relative to various mechanical methods. System prototypes were developed, characterized, and tested in a microgravity environment to demonstrate feasibility. Flux pinning models were developed that accounts for magnet geometry, superconductor geometry, superconductor training geometry, superconductor temperature, superconductor material properties, and magnetic field shape, and output forces and torques the superconductors imparts on the OS via the magnets. Magnetic models of the OS were developed to evaluate magnetic shield effectiveness and demonstrate successful shielding of the sample. A vision system using AprilTag fiducials was used on a free-floating OS in a microgravity environment to estimate relative OS position and orientation while in motion. Integrated Capture, Containment, and Return System (CCRS) Capture and Orient Module (COM) payload concepts for an Earth Return Orbiter (ERO) using flux pinning were proposed and assessed based on relevant system evaluation criteria, such as mass, actuator count, and power consumption.
      • 02.0609 A Milli-newton Propulsion System for the Asteroid Mobile Imager and Geologic Observer (AMIGO) Jekan Thangavelautham (University of Arizona), Greg Wilburn (University of Arizona) Presentation: Greg Wilburn - Thursday, March 7th, 11:00 AM - Jefferson
        Here we present a system overview of the AMIGO concept. The presentation will describe the overall system design followed by description of science instruments and mission goals. The presentation will culminate with dynamic simulations of the hopper traversing an asteroid.
      • 02.0610 A Flight-traceable Cryogenic Thermal System for Use in a Sample-capture Flux-pinned Interface Ian Mc Kinley (Jet Propulsion Laboratory), Christopher Hummel (jet propulsion laboratory), Laura Jones Wilson (Jet Propulsion Laboratory) Presentation: Ian Mc Kinley - Thursday, March 7th, 11:25 AM - Jefferson
        Flux-pinned interfaces for spacecraft have been studied for almost a decade for their dynamic properties that allow designers to shape the dynamic behavior of spacecraft relative to one another. However, the efficacy of these interfaces hinges on the requirement that the type-II superconductors in the interface first be cooled below their critical temperature in the presence of a magnetic field, then held below their critical temperature for the duration of the dynamic interaction. Ground-based research often relies on consumable liquid nitrogen to cool the superconductors, but little work has been published on a flight-traceable cryocooler-based solution to meet the thermal constraints. This work provides estimates of the mass, power, and performance of a system to facilitate trade studies for potential spacecraft applications. This paper details a thermal system designed to cool three 16 mm thick, 56 mm diameter Yttrium Barium Copper Oxide disks to below their critical temperature of 88 K for a ground-based testbed. Data collected on the device shows that it successfully provides the thermal environment required for the flux-pinned interface while consuming 105 W of power. A thermal model accurately predicts heat flows and temperatures in the device. This model applied to a space environment predicts a power consumption of 67 W in a space-flight device.
      • 02.0611 EURO-CARES - a European Sample Curation Facility for Sample Return Missions. Lucy Berthoud (University of Bristol) Presentation: Lucy Berthoud - Thursday, March 7th, 11:50 AM - Jefferson
        EURO-CARES (European Curation of Astromaterials Returned from the Exploration of Space) was a three-year multinational project (2015-2017) funded by the European Commission's Horizon 2020 research programme. The objective of EURO-CARES was to create a roadmap for the implementation of a European Extra-terrestrial Sample Curation Facility (ESCF). This facility was intended to be suitable for the curation of samples from return missions from the Moon, asteroids, Mars, and other bodies of the Solar System. The EURO-CARES project covered five technical areas, led by scientists and engineers from institutions across Europe. 1. Planetary Protection: Planetary protection requirements and implementation approaches were assessed by experts and guided by international policy. Existing sterilization methods and techniques were reviewed. It was found that measures already employed for high containment biosafety facilities are suitable for a restricted sample return mission. However, the development of certain technologies, such as a ‘double walled’ isolator, remote manipulation, integration of scientific analytical instruments, etc., is also required. 2. Facilities and Infrastructure: Aspects from building design to storage of the samples were examined in the project. Requirements for the facility included that it contained a receiving laboratory, a cleaning and opening laboratory, a bio-assessment laboratory, a curation laboratory, and sample storage. Different design solutions were prepared in collaboration with architects. 3. Instruments and Methods: The methodology of characterisation of returned samples and the instrument base required at the ESCF were determined. The analyses provide an appropriate level of characterisation while ensuring minimal contamination and minimal alteration of the sample. When the samples are returned to Earth, several stages of studies would be conducted. 4. Analogue Samples: Analogue proxy samples were considered critical for testing sample handling, preparation techniques, storage conditions, planetary protection measures, as well as to validate new analytical methods. A list of useful analogue samples has been assembled. 5. Sample Transport: The Earth re-entry capsule from a sample return mission is targeted at a specific landing ellipse on Earth and must then be transported safely to the ESCF in an appropriate transport container. Lessons learned from past sample return missions show that preparations for recovery included: training of the recovery team for every possible scenario, possible temporary facilities nearby the landing site, environmental measurements and collection of samples at the landing site, added to this if necessary, would be planetary protection measures. In conclusion, long-term curation of extra-terrestrial samples requires that the samples are kept clean to minimize the risk of Earth contaminants, at the same time as contained, in case of a restricted sample return. This work describes a roadmap for a combined high containment and ultraclean European sample curation facility and the development of the necessary novel scientific and engineering methods and techniques.
      • 02.0612 Energy Modeling of VTOL Aircraft for Titan Aerial Daughtercraft (TAD) Concepts Daiju Uehara (The University of Texas at Austin), Larry Matthies (Jet Propulsion Laboratory) Presentation: Larry Matthies - Thursday, March 7th, 04:30 PM - Jefferson
        Aerial vehicles are of considerable interest for exploration of Saturn’s icy moon Titan. The concept of Titan Aerial Daughtercraft (TAD) was introduced in 2014, where small-scale (e.g. < 10 kg) VTOL aircraft would conduct multiple sorties from a mothership (lander or balloon), recharging batteries from a radioisotope power source (RPS) on the mothership between sorties. More recently, NASA has funded a study of a much larger Titan rotorcraft (∼ 450 kg) that would carry its own RPS. The TAD concept is still worth further analysis as a low-cost element of mission architectures where the mothership is a lander, balloon, or other large mobility system. To compare the potential performance of daughtercraft that are rotary-wing only or fixed/rotary-wing hybrids, this study examines potential flight durations and flight radius for small-scale (4 to 10 kg) quadcopters and tailsitters. For notional system parameters, a payload mass fraction of 25%, and a conservative battery model, energy estimation modeling for lander-based scenarios shows maximum flight endurance at Titan’s surface for 10 kg quad- copter and tailsitter as 9.3 hours and 12.4 hours, respectively, and maximum sortie radius from a lander as 89 km and 125 km, respectively. Modeling of balloon-based scenarios estimated the mass potentially available for payload as a function of the total TAD mass and the float altitude of the balloon. For a balloon floating at 10 km above the surface and a 10 kg TAD, the model gave available mass of about 2.8 kg for a quadcopter and 3.5 kg for a tailsitter. Non-aerodynamic power dominates aerodynamic power at the lowest mass, but becomes a less significant fraction of the total as mass increases. The tailsitter has little or no advantage over the quadcopter at the lowest mass, but increasing advantage as mass increases.
    • 02.07 In Situ Instruments for Landed Surface Exploration, Orbiters, and Flybys Stephanie Getty (NASA - Goddard Space Flight Center) & Ricardo Arevalo (University of Maryland) & Xiang Li (University of Maryland, Baltimore County)
      • 02.0701 Opportunities in NASA Planetary Science Instrument Development Rainee Simons (NASA - Headquarters), James Gaier (NASA - Glenn Research Center), Florence Tan (NASA Headquarters) Presentation: Rainee Simons - Friday, March 8th, 08:30 AM - Jefferson
        Priority questions in Planetary Science for the next decade published in “Vision and Voyages for Planetary Science in the Decade 2013-2022” identified 3 themes; understanding solar system beginnings, searching for the requirements for life in planetary habitats, and revealing planetary processes through time. Science instruments for future missions require a focused technology development strategy to mature critical technologies for measurements that could provide answers. The paper presents the evolution of the instrument development programs in the Planetary Science Division within the Science Mission Directorate. Specifically, the goals and objectives of the two instrument development programs within PSD were described; the Planetary Instrument Concepts for the Advancement of Solar System Observations (PICASSO) and the Maturation of Instruments for Solar System Exploration (MatISSE). These programs solicit innovative technologies that substantially improve instrument measurement capabilities for mission focus areas described in the Decadal Survey or the Science Plan. Additionally, instruments that were developed and matured under current and previous PSD instrument development and maturation programs that were selected for flight missions are presented. These flight missions are Psyche, Europa Clipper, Mars 2020 Rover, LunaH-Map, and BepiColombo.
      • 02.0702 Development of a Nucleic Acid-Based Life Detection Instrument Testbed Srinivasa Bhattaru (Massachusetts Institute of Technology), Jacopo Tani (MIT), Kendall Saboda (Massachusetts Institute of Technology), Christopher Carr (Massachusetts Institute of Technology) Presentation: Srinivasa Bhattaru - Friday, March 8th, 08:55 AM - Jefferson
        Future space instruments will explore increasingly complex questions about our universe, including the origin of life on Earth and the presence of life elsewhere. These instruments will likely integrate chemical and biological subsystems that will face unique challenges; existing protocols typically require non-stabilized components and manual handling. The Search for Extra-Terrestrial Genomes (SETG) instrument is being developed for in situ extraction and sequencing of nucleic acids as a biomarker of life on other planetary bodies. Such sequencing is being implemented using a nanopore-based device, the Oxford Nanopore Technologies (ONT) MinION; as such, it needs to integrate many benchtop-based protocols. Here we describe an automated testbed, designed and built to automate and rapidly prototype extraction, library preparation, and sequencing protocols that could be used in our instrument. The system is designed to be modular with respect to components, facilitating hardware and software modifications with minimal system impact, while also precise across multiple test runs, allowing for accurate evaluation of the impact of varying system inputs as well as exploration of system failure modes and potential solutions. We also present testing results from each of the three primary subsystems (extraction, library preparation, and sequencing) as well as a plan for and initial data on subsystem integration into an end-to-end system. The extraction subsystem is able to match or approach nucleic acid yields attained via manual testing for B. subtilis spores in water (∼ 15%) and spores in basalt (∼ 12%). The library preparation subsystem can successfully prepare a library of E. coli DNA that can be identified after sequencing. The loading/sequencing subsystem has successfully automated sequencer loading, resulting in a sequencing run producing 1.4 billion bases after 1 day of sequencing from a pre-prepared sample. These testing results provide valuable data about the challenges of biological protocol automation, while directly informing future design decisions for SETG. In the process, the lessons learned from this milestone are relevant to the technological development of future planetary science instruments that take advantage of molecular biology techniques.
      • 02.0703 Enabling Measurement of Darwinian Evolution in Space Kendall Saboda (Massachusetts Institute of Technology), Christopher Carr (Massachusetts Institute of Technology) Presentation: Kendall Saboda - Friday, March 8th, 09:20 AM - Jefferson
        A common definition of life is a "self-sustaining chemical system capable of Darwinian evolution," or natural selection of inherited variations that contribute to survival and reproduction. Thus, measuring Darwinian evolution would seem highly relevant to searching for life beyond Earth. While it is now feasible to track evolution in the laboratory, such an experiment has not yet been reported in space. Prior work has demonstrated the ability of microorganisms to adapt to multiple extremes relevant to space and potentially habitable niches beyond Earth. For example, Wassmann and colleagues cultured the gram-positive bacterium Bacillus subtilis 168 under the selective pressure of ultraviolet (UV) radiation (200-400 nm) akin to that found on Mars over 700 generations; the resulting population was found to be significantly more resistant than the ancestral line to both UV and other stresses, including increased salinity, vacuum, desiccation, and ionizing radiation. More recently, Tirumalai et al. cultured Escherichia coli in ground-based low-shear modeled microgravity for 1000 generations revealing 5 coding mutations of not-yet-characterized significance. Miniaturization of nucleic acid extraction and sequencing technologies is enabling development of space instruments targeting nucleic acids, including work by our group and recent use of a nanopore sequencer on the International Space Station (ISS). In addition, NASA plans to deploy a deep space cubesat, BioSentinel, with a biological payload, to characterize the ability of yeast to carry out DNA repair in space. Critically, this system demonstrates the capability to initiate, sustain, and characterize biological systems in space-compatible formats. Here we describe how these advances can be integrated to enable in-situ measurement of Darwinian evolution, with applications for understanding adaptation to space and for future life detection missions. Specifically, we focus on applying nanopore sequencing to detect and characterize evolution in the lab and propose a system to autonomously measure evolution in space as an extension of the Search for Extraterrestrial Genomes (SETG), an instrument under development for in-situ nucleic acid-based life detection. The minimal approach would involve sequencing before and after a culturing period during which organisms of interest would be exposed to a simulated or actual stressor. An integrated system for measuring Darwinian evolution in space would not only allow for definitive measurement of nucleic-acid based life; it could also be used to improve understanding of microbial life’s ability to adapt to the harsh conditions of space and, in doing so, support human health beyond Earth and inform future use of synthetic-biology during deep space missions.
      • 02.0704 In-Situ Close-Range Imaging with Plenoptic Cameras Martin Lingenauber (German Aerospace Center - DLR), Ulrike Krutz (), Florian Fröhlich (German Aerospace Center - DLR), Christian Nissler (German Aerospace Center (DLR)), Klaus Strobl (German Aerospace Center (DLR)) Presentation: Martin Lingenauber - Friday, March 8th, 09:45 AM - Jefferson
        This work discusses the concept of plenoptic hand lens imagers for in-situ close-range imaging during planetary exploration missions. Hand lens imagers, such as the Mars Hand Lens Imager on-board the Mars rover Curiosity, are important cameras for in-situ investigations, e.g. of rock layer, minerals or dust. They are also important for the preparation and documentation of other instrument operations and for rover health assessment. Due to the small working distance between object and the camera's main lens, significant physical limitations affect the imaging performance. Most evident is the limited depth of field of a few millimeters for working distances of a few centimeters. This requires a highly accurate positioning of the camera and also limits the in-focus content of an image significantly. Hence, in order to have an extended object completely in focus, a sequence of images, each being focused to a different distance, is required. A single, passive camera is insufficient to compute depth from a single shot; only the combination of multiple images, either taken from different vantage points or at different focal settings, allows this. To overcome those limitations, we propose the use of plenoptic cameras as hand lens imagers. From a single exposure, they allow to create an extended depth of field image and at the same time a metric depth map while maintaining a more open aperture. These and other advantages might make it possible to omit space grade focus mechanisms in the future. A plenoptic camera is achieved by adding an additional matrix of lenslets shortly in front of the image sensor of a conventional camera. Hence, available space camera hardware can be used to form a new type of sensor. Due to its recording concept, a plenoptic camera maintains the depth of the scene as it is projected into the camera by the main lens. Thanks to the parallax between the lenslets, it is possible to compute depth via triangulation for each image point as well as a high resolution 2-D extended depth of field image. This paper provides an overview of the state of the art of hand lens imaging from which we derive a set of common requirements for future devices. We briefly introduce the plenoptic camera technology and provide first experimental results on the imaging performance based on samples of test targets and rocks. The results show that our preliminary plenoptic camera setup can comply with the requirements for in-situ hand lens imaging in terms of image quality, depth estimation and the usability for planetology.
      • 02.0705 A Chip-Scale Plasmonic Spectrometer for in Situ Characterization of Solar System Surfaces Nancy Chanover (New Mexico State University), David Voelz (New Mexico State University) Presentation: Nancy Chanover - Friday, March 8th, 10:10 AM - Jefferson
        We discuss the development of a plasmonic spectrometer for in situ characterization of solar system surface and subsurface environments. The two goals of this effort are to (1) quantitatively demonstrate that a plasmonic spectrometer can be used to rapidly acquire high signal-to-noise spectra between 0.5 - 1.0 microns at a spectral resolution suitable for unambiguous detection of spectral features indicative of volatiles and characteristic surface mineralogies, and (2) demonstrate that this class of spectrometer can be used in conjunction with optical fibers to access subsurface materials and vertically map the geochemistry and mineralogy of subsurface layers, thereby demonstrating that a plasmonic spectrometer is feasible in a low-mass, low-power, compact configuration. Our prototype spectrometer consists of a broadband lamp/source, a fiber optic system to illuminate the sample surface and collect the reflected light, a mosaic filter element based on plasmon resonance, and a focal plane array (FPA) detector. The critical filter element of the spectrometer is based on the internal plasmon resonance of metallic nanostructures. Unlike conventional grating-based spectrometers, the spectral resolution of the spectrometer is mainly determined by two parameters: the spectral width of the resonance peak and the tunability of the center wavelength of resonance. Our initial numerical simulations revealed that periodic nanostructures in a thin gold membrane provide a narrow resonance peak. In addition, the resonant peak is highly tunable within the target wavelength range. We developed a membrane-based plasmonic filter that can directly be implemented on an optical fiber. First, we developed a new fabrication process for nanostructures in thin Au membranes (100 ~ 500 nm) suspended in air. For fabrication, periodic nanoscale circular hole arrays were patterned in a 500 nm thick Au film using a focused-ion-beam milling system. The Au film was separated from the substrate using a highly selective chemical etching process. Our initial findings showed that we can control the central wavelength of the filter by changing the index of refraction of the surrounding medium, thus we explored several media (e.g. water, glycerol, glucose) as a means of introducing a range of indices of refraction, and thus central wavelengths of the filter, using microfluidic channels. In addition to the development of the plasmon filter element, we constructed a testbed to explore the use of optical fibers for source illumination and signal transmission to the focal plane array. We discuss our preliminary design studies of the plasmonic nanostructure prototypes and their application to miniaturized instrumentation for in situ characterization of solar system surface and subsurface environments.
      • 02.0706 Linear Ion Trap Mass Spectrometer (LITMS) for in Situ Astrobiology Xiang Li (University of Maryland, Baltimore County), Andrej Grubisic (NASA Goddard Space Flight Center), Marco Castillo (University of Maryland), Friso Van Amerom (), Ryan Danell (Danell Consulting, Inc.), Desmond Kaplan (KapScience LLC), Ricardo Arevalo (University of Maryland), William Brinckerhoff (NASA - Goddard Space Flight Center), Kris Zacny (Honeybee Robotics Spacecraft Mechanisms Corporation), Philip Chu (Honeybee Robotics) Presentation: Xiang Li - Friday, March 8th, 10:35 AM - Jefferson
        The Linear Ion Trap Mass Spectrometer (LITMS) instrument is a compact, highly-capable next-generation suite for spaceflight, poised to expand the scope and depth of knowledge of Mars and other planetary bodies through our science measurement objectives. The LITMS instrument is based substantially on the Mars Organic Molecule Analyzer - Mass Spectrometer (MOMA-MS) for the 2020 ExoMars mission but features further analytical enhancements. In addition to the core MOMA capabilities, LITMS enhances the instrument performance by including negative ion detection, a dual frequency RF power supply to increase mass range, precision subsampling of drill cores at fine (≤ 1 mm) spatial scales, and pyrolysis of powdered sample for evolved gas analysis (EGA) of organic content and mineral assemblages. LITMS enables in situ characterization of inorganics and organics in individual rock core layers and features. In this presentation, I will first briefly summarize the MOMA-based design features on LITMS, and then focus on the unique LITMS designs and corresponding demonstrations of the novel analytical capabilities they enable.
      • 02.0708 Raman-LIBS, a Journey from Mars to Earth via the Moon. Andrew Court (TNO) Presentation: Andrew Court - Friday, March 8th, 11:00 AM - Jefferson
        In 2005 ESA initiated a study for a spectrometer combining Raman and Laser Induced Breakdown Spectroscopy (LIBS) as a potential instrument for the Pasteur payload of the ESA ExoMars rover. It is a fundamental, next-generation instrument for organic, mineralogical and elemental characterization of soil, rock samples and organic molecules. The objective was to combine Raman spectroscopy and LIBS (R-L) into a single instrument sharing many hardware commonalities. The resulting ‘elegant bread board’ (EBB) was successfully tested in ‘Mars’ like condition. Ultimately a reduced Raman only instrument was selected. In a later ESA study, the R-L system was adapted for use in a lunar rover and, again, the EBB was used under high vacuum conditions, and demonstrated that in situ laser analysis of regolith like materials was possible under high vacuum conditions. The developed knowledge and technology has continued to be used here on Earth with various spin-offs into industrial and medical applications. This presentation will describe the origin of the R-L technology and its path through the different Space roles on into the spin-off systems which are now transferring into Earth based systems and will look toward the potential role of R-L in future space missions to asteroids and comets.
      • 02.0709 Nucleic Acid Sequencing under Mars-like Conditions Christopher Carr (Massachusetts Institute of Technology) Presentation: Christopher Carr - Friday, March 8th, 11:25 AM - Jefferson
        All known life uses informational polymers based on nucleic acids. Future missions to Mars and Ocean Worlds such as Enceladus and/or Europa may target these or related polymers in the search for extant life beyond Earth. Nanopore-based devices represent a promising approach for sensing and characterizing these, and possibly other, biomarkers. Here we demonstrate low-input (200 pg) DNA sequencing, equivalent to extraction from 10^6 Bacillus subtilis spores at 5 percent extraction yield, using the Oxford Nanopore MinION in a thermal vacuum chamber under Mars-like temperature (-60˚C), atmosphere (100% CO2), and pressure (400 to 500 Pa). Current limits of detection correspond to 2 to 5 pg DNA. With additional advances in nucleic acid extraction and library preparation efficiency, a sequencing-based approach to life detection will be viable at cell densities representative of the most extreme Mars analog environments here on Earth.
    • 02.08 Q/V band connectivity and Alphasat experience Giuseppe Codispoti (ASI, Italian Space Agency) & Giorgia Parca (Italian Space Agency)
      • 02.0801 High Power Transmitters for Q/V-band Communications- beyond Alphasat Naresh Deo () Presentation: Naresh Deo - Wednesday, March 6th, 11:00 AM - Jefferson
        Since the delivery of the Q-band Solid-State Power Amplifiers (SSPA) for Alphasat TDP5 in 2012 and their successful operation in space for over 5 years, very significant advances have been made in the technology and design of SSPAs thereby greatly enhancing their performance, suitability and reliability for space payloads while reducing their size, mass and cost. The most important of these developments is the vast improvement in the capabilities and maturity of Gallium Nitride (GaN)-based MMIC power amplifiers in Q/V-bands and higher. Other critical factors include innovative circuit integration techniques, novel manufacturing methods and advanced materials. Given the same mechanical outline, the emerging technologies can generate more than four times the RF power output, two times the efficiency and an order of magnitude higher reliability than the original Gallium Arsenide (GaAs) MMIC-based SSPA for Alphasat Q/V Communications payload. Newly developed GaN MMIC power amplifier devices can generate two-to-three times the RF power output at twice the efficiency of their GaAs counterparts in the same frequency range thus increasing the power output per unit volume by a large factor while lowering the total DC power consumption. Furthermore, GaN devices can operate at much higher channel temperatures (>165 deg. C) with reliability (MTTF) consistent with long-term (>15 years) use in space equipment. Recent initiatives by industry and space organizations have also resulted in procedures and standards for space-qualification and reliability assessment for GaN devices. In this paper, we will present a design concept that can generate 50 to 100 Watts of RF power over the 37.5-42.5 GHz band with power-added efficiency approaching 25-30% within approximately the same footprint, outline and weight as the original Alphasat SSPA. Highly efficient, robust and compact power combining methods developed for this family of SSPAs make use of novel materials and manufacturing processes to further enhance the capabilities of the Q-band SSPA. Another useful feature of the approach adopted for the SSPAs is modularity of their construction, which allows rapid development and manufacture of customized transmitters for various payload requirements. The paper also describes the design, construction and measured performance of several SSPAs at other operating frequencies in the millimeter-wave domain. With the explosive growth in small satellites, such a CubeSats, the incentive to develop SSPAs suitable for their payloads will also be addressed. Examples of transmitters for various applications in various platforms are included.
      • 02.0802 Optimization of Q/V-band Smart Gateway Switching in the Framework of Q/V-Lift Project Tommaso Rossi (University of Rome Tor Vergata), Carlo Riva (Politecnico di Milano), Lorenzo Luini (Politecnico di Milano), Mauro De Sanctis (Universití di Roma Tor Vergata, Dip. Ing. Elet.), Marina Ruggieri (University of Roma "Tor Vergata"), Giuseppe Codispoti (ASI, Italian Space Agency), Giorgia Parca (Italian Space Agency), Giandomenico Amendola (universita della calabria) Presentation: Giorgia Parca - Wednesday, March 6th, 11:25 AM - Jefferson
        High Throughput Satellite systems are expected to reach the milestone of terabit/s capacity in few years through the exploitation of Extremely High Frequencies (EHF), in particular Q/V-bands and W-band, in the feeder link. In this respect, the H2020 QV-LIFT project, kicked-off in November 2016, aims at filling crucial gaps in the ground segment technology required by future Q/V-band HTS systems. One of the most challenging objectives of QV-LIFT team is develop and test a smart gateway management system (SGMS) operating in the Q/V- band. The SGMS will implement fade mitigation techniques able to counteract the detrimental propagation impairments across the feeder link. This paper reports the optimization and simulation activities that have been performed to design SMGS control logic, with a focus on the atmospheric channel predictor and switching decision algorithm. The channel is fully characterized by synthetic time series of rain attenuation generated by a Multi-site Time-series Synthesizer (MTS).
      • 02.0803 SDN for Smart Gateway Diversity Optimization in High Throughput Satellite Systems Tommaso Rossi (University of Rome Tor Vergata), Ernestina Cianca (Univiversity of Rome Tor Vergata), Marina Ruggieri (University of Roma "Tor Vergata") Presentation: Claudio Sacchi - Wednesday, March 6th, 11:50 AM - Jefferson
        Future satellite networks could benefit from new paradigms that are currently applied to terrestrial networks, as Software Defined Networking (SDN) and Network Functions Virtualization (NFV); these can improve key system characteristics as flexibility, customization, scalability, etc. This paper presents an analysis on the use of SDN for the optimization of High throughput Satellite (HTS) systems. The latter will use EHF (in particular beyond Ka-band frequencies, such as Q/V and W bands) in the feeder link and in this framework it is mandatory to use spatial diversity to counteract tropospheric fading. One of the most interesting diversity scheme is “smart gateway”; this technique has to be carefully optimized to achieve high system performance. This paper shows that SDN is a good candidate for the intelligent management of this system. In particular, the paper shows an analysis of the use of the SDN paradigm for smart gateway so-called “N+0” and “N+P” diversity schemes. The two schemes allow, in case of heavy fading conditions on one gateway, the redirection of the user traffic towards a redundant gateway (N + P), or the partition of the lost capacity over different active gateways (N + 0), ensuring service continuity.
    • 02.09 Mission Design for Spacecraft Formations Giovanni Palmerini (Sapienza Universita' di Roma)
      • 02.0901 Reconstruction of the Shape of a Tumbling Target from a Chaser in Close Orbit Giovanni Palmerini (Sapienza Universita' di Roma), Renato Volpe (), Marco Sabatini (Universita` Roma La Sapienza) Presentation: Giovanni Palmerini - Monday, March 4th, 09:25 PM - Madison
        The reconstruction by the chaser of the relative pose of a target is a crucial step in autonomous in-orbit operations, especially if non-cooperative. The focus of the paper is on the visual navigation techniques helping in such a goal, made even more complex by the discontinuous visibility of the features of a target considered in a rather general condition of motion. The estimation scheme, based on the Unscented Kalman Filter, proposed to determine the relative kinematic state is also considered. As a final result, also the shape of the previously unknown target spacecraft could be roughly identified.
    • 02.10 Space Radiation and its Interaction with Shielding, Electronics and Humans Lembit Sihver (Technische Universität Wien) & Maria De Soria Santacruz Pich (Jet Propulsion Laboratory)
      • 02.1001 Radiation Risks and Countermeasures for Humans on Deep Space Missions Lembit Sihver (Technische Universität Wien), S. M. Javad Mortazavi (University of Wisconsin Milwaukee) Presentation: Lembit Sihver - Monday, March 4th, 04:30 PM - Madison
        The radiation environment encountered in space differs much in nature from that on Earth, with contribution of protons and high energetic ions up to iron, resulting in radiation levels far exceeding the ones present on Earth. Accurate knowledge of the physical characteristics of the radiation field, the solar activity and the mission length, which influence the radiation risks for humans on deep space missions, e.g. to Mars, is therefore very important. It has been estimated that the transit times for a human mission to Mars vary from 5 to 7 months each way, with a typical figure of about 6 months for a long duration stay on Mars, up to 8 – 10 months each way for a short duration stay on Mars. That means that the astronauts will be exposed to a harsh radiation environment for at least 2-3 years. This paper describes the radiation environment in deep space, some of the radiation health risks astronauts are exposed to on long term missions, as well as the requirements and limitations of physical protection for reducing these risks. Since it has been shown that physical shielding alone is not adequate for long term deep space missions, we also present the need for new effective methods of biological protection, e.g. ground-based in vitro pre-flight screening of the candidates for evaluation of the magnitude of their adaptive responses. Furthermore, methods for boosting the immune system of astronauts and the possibility of using medical counter-measures are discussed. Notably, the use of vitamin C as a promising non-toxic, cost-effective, easily available radiation mitigator, is described.
      • 02.1002 Does Gender Matter for Radioadaptation and Radiation Susceptibility in Deep Space Missions? S. M. Javad Mortazavi (University of Wisconsin Milwaukee), Lembit Sihver (Technische Universität Wien) Presentation: Lembit Sihver - Monday, March 4th, 04:55 PM - Madison
        Astronauts face a significant risk of cancer when they travel beyond the shielding effect of the Earth’s magnetosphere. While on the ground, women mount a more potent immune response than men, they are more vulnerable to radiation-induced cancer than their male counterparts. However, the differences between the cancer incidence and death rates in men and women can be, at least to some extent, dueto the difference in background rates than a real sensitivity to radiation effects. Moreover, the induction of adaptive response (AR) is another issue that needs specific attention. This paper provides evidence indicating that for a deep space mission such as a future manned journey to Mars, women should be given equal consideration for selection as astronauts.
      • 02.1004 Bayesian Radiation Design Margin for Spacecraft Reliability Prediction Anthony Coburger (Johns Hopkins University Applied Physics Laboratory) Presentation: Anthony Coburger - Monday, March 4th, 09:00 PM - Madison
        A Bayesian reliability model is applied to Total Ionizing Dose (TID) field data. TID damage results when high energy particles interact with onboard semiconductor devices and accumulate charge within the silicon and silicon oxide. The result is a degradation in device performance, circuit performance, device functionality, and an increased risk of device functional failure. Additionally, variability in the space weather environment and the non-deterministic nature of the radiation damage make accurate predictions of on-orbit device response a challenge. These and other sources of uncertainty are currently addressed by applying conservative risk mitigation techniques including Radiation Design Margins (RDM), radiation shielding measures, and worst-case circuit analyses. By leveraging Bayesian methods, the proposed model methodically accounts for this uncertainty in the reliability estimates and reduces it as new data is incorporated.
      • 02.1007 Liquid Shielding Christopher Heistand (Johns Hopkins Univ Applied Physics Lab (JHU APL)), Michelle Donegan (Johns Hopkins University Applied Physics Laborator), Jamie Porter (Department of Nuclear Engineering), Jeffrey Boye (JHUAPL), Michael Marley (Johns Hopkins APL) Presentation: Christopher Heistand - Monday, March 4th, 09:50 PM - Madison
        Liquid Shielding proposes using a non-conductive fluid surrounding the electronics to create an environment benign enough for non space-grade electronics to be flown. Using a pressure vessel, a bath can be formed around the electronics that shields from radiation, protects materials from vacuum, dampens shock and vibration characteristics, increases thermal mass and allows for unique radiation schemes. This concept is focuses on shielding the electronics from Total Dose failure, non-clearable latchups and most mechanical failures, targeting almost uninterrupted uptime, but not immunity from upsets. As long as the part does not fail entirely and is only down temporarily, there are ways to solve the downtime with a redundancy scheme or other software/hardware systems that remain a fraction of the price of a single space grade processor. This presentation first discusses the environment that the Liquid Shielding concept is trying to protect against. It then walks through two down selections; shielding liquids and single board computers (SBC) for our prototype system. Given the liquid, we then identify how thick the shield needs to be. Next, we explain our mechanical design for the given liquid, depth requirement and SBC. Lastly, we explore the prototype and discuss the future testing campaign. Liquid Shielding aims to fix enough of the environmental issues that it allows non space-grade processors to be used in space. By doing so costs come down dramatically (100x), processing power goes up equally so (100x) and flight/instrument software can stop overly optimizing code and start leveraging the rest of the terrestrial world’s software boom.
    • 02.11 Space Debris and Dust: The Environment, Risks, and Mitigation Concepts and Practices Douglas Mehoke (Johns Hopkins University Applied Physics Laboratory (JHU/APL)) & Kaushik Iyer (Johns Hopkins University/Applied Physics Laboratory)
      • 02.1101 Drag-enhancing Deorbiting Devices for Mid-sized Spacecraft Self-disposal Jennifer Rhatigan (Naval Postgraduate School), Josep Virgili Llop (), Marcello Romano (Naval Postgraduate School), Katrina Alsup (), Keith Lobo (Naval Postgraduate School), Jessica Shapiro (Naval Postgraduate School), Bianca Lovdahl (Naval Postgraduate School), Farsai Anantachaisilp (Naval Postgraduate School) Presentation: Jennifer Rhatigan - Monday, March 4th, 08:30 AM - Gallatin
        The current state-of-the-art has established the feasibility of drag-devices for small spacecraft, however the use of drag-devices for mid-sized spacecraft has not yet received the same level of attention. Here we explore the potential benefits and uses of drag devices on mid-sized spacecraft deployed in low Earth orbit (LEO). Methods to de-orbit LEO spacecraft have received increased study since the widespread adoption of orbital debris mitigation standards. These standards dictate that spacecraft shall be passivated and safely disposed of at their end-of-life (EOL). For spacecraft in LEO, an atmospheric disposal within 25 years of EOL is seen as the most cost-effective method. The residual atmosphere present at orbital altitudes causes orbital decay that, at sufficiently low operating altitudes, will naturally de-orbit a spacecraft within the prescribed 25-year period. At higher altitudes, the natural decay can be insufficient and for spacecraft with propulsion the current practice is to reserve fuel for a final de-orbit burn. A drag-enhancing de-orbiting device may be used to increase the spacecraft's cross-sectional area, increasing the aerodynamic drag and shortening its natural decay below the 25-year limit. Here, we explore the trade-space resulting from the variation of the necessary cross-section area increase required for different starting altitudes, in combination with realistic models of a small (50 kg), mid-size (400 kg), and large (2000 kg) spacecraft. The preliminary results of this analysis suggest that drag-devices are well suited for small and mid-sized spacecraft, as only moderate increases in cross-section areas, in the order of ten square meters, are required to reduce the post-EOL orbital lifetime below 25 years. Indeed, the offset of fuel reserved for de-orbit of mid-size spacecraft can be significant, establishing a primary area of study within our trade-space (mid-size spacecraft with propulsion). The required increases in cross-sectional area for large spacecraft, in the order of hundreds of square meters, suggest that drag-devices for large spacecraft remain impractical given the state-of-the-art. In order to establish feasibility, we present a conceptual design of a drag-device for a mid-sized spacecraft with propulsion and suggest possible scenarios for its use. Based on this concept, it appears that given their low mass and simplicity, these drag-devices are an attractive alternative to the classical propulsive de-orbit. Some of the drag-device advantages are straightforward (e.g., lower mass), yet other benefits are derived from the drag-device concept of operations (e.g., extended operational lifetime), or ease of integration (e.g., storable and non-hazardous). The use of a drag-device to augment a classical propulsive de-orbit burn is also explored here, showing that this hybrid approach can extend the use of drag-enhancing de-orbiting devices to significantly higher altitudes while still retaining some its attractive benefits. Finally, a comprehensive analysis of advantages and disadvantages of drag-devices is presented.
      • 02.1102 Regolith Particle Erosion of Material in Aerospace Environments Emma Bradford (JPL), Jason Rabinovitch (Jet Propulsion Laboratory, California Institute of Technology), Mohamed Abid (Jet Propulsion Laboratory) Presentation: Emma Bradford - Monday, March 4th, 08:55 AM - Gallatin
        This presentation would show research on the effect of exposing thermal control S13GP:6N/LO-I white paint, Kapton flex cable, fiber optic cable, HEPA filter, and M55J graphite composite to high-velocity regolith environment that spacecraft landing on Mars are commonly exposed to. Due to the similarity between the Mars 2020 Rover design and Mars Science Laboratory design, it is expected that the Mars 2020 rover will be exposed to a similar high-speed regolith environment that the Mars Science Laboratory was exposed to. This environment is replicated to test the survivability of susceptible materials. The testing is performed at the University of Dayton Research Institute in Dayton, Ohio. The experiments expose different materials to basaltic–like particles ranging in size from approximately 40 μm to 2 cm, at velocities ranging from 19 m/s to 250 m/s, with varied particle fluxes (measured in mg/cm2). Depending on the size of the particle used, the particles can either embed in or erode the material. Post-test analysis shows that all materials tested will survive the expected environment observed during the Mars 2020 landing event. Some materials are tested to failure in order to better characterize material response. Materials that fail in some test scenarios include the paint, fiber optic cable, and the graphite composite. After being exposed to regolith, the α/ε ratio of the paint increased by ~37% due to particles embedding in the paint. Darkening of the paint can negatively affect thermal control of the rover. With high particle mass fluxes, the paint eventually degraded enough to expose the aluminum substrate. When impacted by a 1.5 cm particle traveling at 20 m/s, the fiber optic cable did not sever, but the impact did cause the cable to deform enough to crack the glass, which resulted in a significant increase in attenuation, rendering the cable unable to transmit data. The graphite composite also failed when exposed to high particle fluxes. All of the observed failures occurred for test cases above the expected landing environment with significant margin. Tests performed beyond the requirements help characterize how well these materials will survive in even more extreme environments for future missions.
      • 02.1104 Feasibility Study on a PCL Radar for Space Debris Detection Shota Ochi (Graduate School of Tokai University), Makoto Tanaka (Tokai University) Presentation: Shota Ochi - Monday, March 4th, 09:20 AM - Gallatin
        There are more than 19,000 objects in earth orbit as of 2018. These space objects are tracked by the space surveillance network (SSN). We found it necessary of own radar facilities for searching a lost satellite and space debris through an accident on a small satellite of the past. To establish an own radar facility by a civilian agency as a laboratory of a University, issues concerning many costs, a licensed radio band for transmitters, and a fixed installation location arise. We propose that one of the solutions on this issue is a Passive Coherent Location (PCL) radar. The PCL radar is a low cost and compact radar system due to using 'illuminators of opportunity' as their source of radar transmission instead of a dedicated transmitter. This paper describes a feasibility study on a PCL radar system for space debris detection. The proposed PCL system consists of Earth-orbiting satellites which are transmitting radio waves and a ground-based receiving system. The receiving system consists of a parabolic antenna with high gain and portable SDR equipment with a wideband frequency range. The cost of this system was estimated at less than $20,000, and the weight was less than 50 kg. The volume of the facility is 0.2 % of that of an existing active radar for space debris detection. As a result of the feasibility simulations, it became clear that this proposed PCL radar has a detection capability of space debris from LEO to GEO. Using the JCSAT-3A system, the detectable size converted into the physical silhouette area was 0.70 m^2 at an altitude of 400 km. Using the NOAA-19 system, the detectable size was 0.93 m^2 at an altitude of 800 km.
      • 02.1107 Design and Analysis of a Passive Tether De-Orbiting Mechanism for a Nano-Satellite Avish Gupta (Manipal University), Varun Thakurta (Manipal University), Dhananjay Sahoo (Manipal Institute of Technology), Anirudh Kailaje (Manipal University) Presentation: Avish Gupta - -
        Through this presentation, we aim to characterize the forces acted upon a 2U-class Nano-satellite by a passive electrodynamic tether system used as an inexpensive, space and mass efficient deorbiting mechanism in the Low Earth Orbit (LEO). By the IADC guidelines, an object in the low earth orbit should not have an orbital lifetime exceeding 25 years which can be attained by the satellites themselves due to significant atmospheric drag. We aim to create a deorbiting system which will create a force, always opposing the motion of the satellite, increases the eccentricity of the satellite orbit causing it to burn up at the perigee in under 2 years as opposed to 25 years. The de-orbiting system involves a spool with an electrically conducting thread wound around it. It is ejected using a spring-loaded mechanism with the other end of the thread secured to the satellite body. The shape of the spool and the type of winding have been optimized to ensure maximum packing efficiency and a stable ejection. Once deployed, various forces act on the satellite system due to the interaction of the conductive thread with the time-varying magnetic field and the ambient plasma. A detailed study on the respective forces and its effects on the satellite’s orbit has been carried out in this paper.
      • 02.1108 Modeling Hypervelocity Impact Temperatures for Europa Clipper Planetary Protection Anthony Mark (Johns Hopkins Applied Physics Laboratory), Kaushik Iyer (Johns Hopkins University/Applied Physics Laboratory), Douglas Mehoke (Johns Hopkins University Applied Physics Laboratory (JHU/APL)), Wayne Dellinger (JHU-APL), Hayden Burgoyne (), Michael Di Nicola (Jet Propulsion Laboratory), Kelli Mc Coy (NASA Jet Propulsion Lab), Ethan Post () Presentation: Anthony Mark - Monday, March 4th, 09:45 AM - Gallatin
        A scarcely explored means for reducing the probability of biological contamination of a planetary body when inadvertently impacted by an Earth-origin spacecraft is the heat generated by the impact event itself. This paper formulates some necessary considerations and an appropriate analytical approach for modeling and estimating impact induced plastic deformation heat generation in spacecraft metallic components and sub-systems, and applies it to the Europa Clipper mission. Plastic deformation heat generation and other mechanisms were then used as inputs to a separate model developed to compute biohazard mitigation. Considerable temperature increases capable of providing biological sterility for some, but not all of the Europa Clipper’s spacecraft components is indicated.
      • 02.1110 Autonomous Active Space Debris-removal System Shriya Kaur Chawla (SRM institute of science and technology), Vinayak Malhotra (SRM University) Presentation: Shriya Kaur Chawla - Monday, March 4th, 10:10 AM - Gallatin
        Space exploration has noted an exponential rise in the past two decades. The world has started probing the alternatives for efficient and resourceful sustenance along with utilization of advanced technology viz., satellites on earth. Space propulsion forms the core of space exploration. Of all the issues encountered, space debris has increasingly threatened a space exploration and propulsion. The efforts have resulted in the presence of disastrous space debris fragments orbiting the earth at speeds up to several kilometres per hour. Unscaled debris is universally projected as potential damage to the future missions with loss of resources, and mankind as a huge amount of money is invested into it. Appreciable work had been done in the past relating to active space debris removal technologies such as harpoon, net and drag sail. The primary emphasis is laid on confined removal. Recently, remove debris spacecraft was used for servicing and capturing cargo ships. Airbus designed and planned the debris-catching net experiment aboard the spacecraft. The spacecraft represents the largest payload deployed from the space station. However, the magnitude of the issue suggests that active space debris removal technologies, such as harpoons and nets, still would not be enough thus necessitating the need for better and operative space debris removal system techniques. Such techniques based on diverting the path of debris or the spacecraft to avert damage, have turned out minimal usage owing to limited predictions. Present work focuses on an active hybrid space debris removal system. The work is motivated by the need to have safer and efficient space missions. The specific objective of the work is to thoroughly analyse the existing and conventional debris removal techniques, their working, effectiveness, and limitations. Thus, a novel active space debris removal system 'SMUDHRAS' is proposed. Second is to understand the role of key controlling parameters in coupled operation of debris capturing and removal. 'SMUDHRAS' represents the utilization of the latest autonomous technology available with an adaptable structural design for operations under varying conditions. The design covers advantages of most of the existing technologies while removing the disadvantages. The system is likely to enhance the probability of effective space debris removal.
      • 02.1111 Multiple Debris Orbital Collision Avoidance Ahmed Hamed (NARSS), Ahmed Badawy (October University for Modern Sciences and Arts), Adel Omar (Military Technical College, Cairo Egypt), Mahmoud Ashry (), Wessam Hussein (MTC) Presentation: Wessam Hussein - Monday, March 4th, 10:35 AM - Gallatin
        the presentation will handle firstly, the problem of collision avoidance and its effects on space missions , secondly, the ways of defining the collision risks with the model used for orbit propagation which compared to HPOP module in STK and also with simplified general perturbations propagator , thirdly, the technique used to escape from such risks and finally, assessment of this technique over other techniques
    • 02.12 Asteroid Detection, Characterization, Sample-Return, and Deflection Paul Chodas (Jet Propulsion Laboratory) & Jeffery Webster (Jet Propulsion Laboratory)
      • 02.1204 Concurrent Redirection and Attitude Control of an Asteroid M. Reza Emami (Luleå University of Technology), Michael C. F. Bazzocchi (University of Toronto) Presentation: M. Reza Emami - -
        This paper demonstrates the applicability of two low-thrust spacecraft for the task of concurrently redirecting an asteroid and controlling its attitude. Through the use of available observational data, a synthetic near-Earth asteroid, with suitable characteristics for a resource utilization mission, is designed. The asteroid is given an initial orientation and angular velocity, such that it is in a tumbling state. The two spacecraft are attached to the asteroid surface, and employ low-thrust ion thrusters for the attitude control and redirection of the asteroid. The spacecraft first detumble the asteroid body using their torque-inducing thrusters, and then re-orient the asteroid such that the redirection thrusters are aligned with the redirection thrust vector. The spacecraft then ensure the asteroid’s orientation is aligned with the redirection thrust vector throughout the entire trajectory transfer maneuver, while ensuring the angular velocity remains bounded around zero. The trajectory design is a low-thrust maneuver, based on Gauss’ variational equations, which redirects the asteroid from its orbit about the Sun to rendezvous with Earth. A linear control law is employed for both the detumbling and redirection maneuver with attitude control. The overall performance of the system and the applicability of the approach are discussed.
      • 02.1205 Projecting Asteroid Impact Corridors onto the Earth Clemens Rumpf (MCT/NASA Ames Research Center), Donovan Mathias (MCT/NASA Ames Research Center), Davide Farnocchia (Jet Propulsion Laboratory), Steven Chesley (Jet Propulsion Laboratory) Presentation: Clemens Rumpf - Thursday, March 7th, 08:30 AM - Amphitheatre
        The subject of this presentation is asteroid impacts and impact risk analysis. This talk focuses on inferring impact probability distributions to a set of pre-computed impact locations. In addition, the method of calculating impact locations based on asteroid orbital information will be briefly introduced.
      • 02.1206 The Pan-STARRS Data Archive — a Treasure Trove of Moving Object Observations Richard Wainscoat (University of Hawaii), Robert Weryk (University of Hawaii) Presentation: Richard Wainscoat - Thursday, March 7th, 08:55 AM - Amphitheatre
        The Pan-STARRS data archive will be described, along with its utility for finding archival observations of Near-Earth Objects.
      • 02.1207 Solar Sails for Planetary Defense and High-Energy Missions Jan Thimo Grundmann (DLR German Aerospace Center), Waldemar Bauer (German Aerospace Center - DLR), Jens Biele (DLR), Ralf Boden (The University of Tokyo), Kai Borchers (German Aerospace Center - DLR), Matteo Ceriotti (University of Glasgow), Federico Cordero (Telespazio-Vega Deutschland GmbH), Bernd Dachwald (FH Aachen University of Applied Sciences), Etienne Dumont (German Aerospace Center - DLR), Christian Grimm (German Aerospace Center - DLR), David Hercik (TU-Braunschweig), Tra Mi Ho (German Aerospace Center - DLR), Rico Jahnke (), Aaron Koch (DLR e. V.), Caroline Lange (German Aerospace Center - DLR), Roy Lichtenheldt (German Aerospace Center - DLR), Volker Maiwald (German Aerospace Center (DLR)), Colin Mc Innes (University of Glasgow, School of Engineering), Jan Gerd Meß (German Aerospace Center - DLR), Tobias Mikschl (Uni Wuerzburg), Eugen Mikulz (), Sergio Montenegro (University Würzburg), Ivanka Pelivan (), Alessandro Peloni (University of Glasgow), Dominik Quantius (German Aerospace Center - DLR), Siebo Reershemius (German Aerospace Center - DLR), Thomas Renger (German Aerospace Center - DLR), Johannes Riemann (), Michael Ruffer (), Kaname Sasaki (German Aerospace Center - DLR), Nicole Schmitz (German Aerospace Center - DLR), Wolfgang Seboldt (), Patric Seefeldt (German Aerospace Center - DLR), Peter Spietz (DLR German Aerospace), Tom Sproewitz (German Aerospace Center), Maciej Sznajder (German Aerospace Center - DLR), Simon Tardivel (CNES), Norbert Toth (German Aerospace Center - DLR), Elisabet Wejmo (German Aerospace Center - DLR), Friederike Wolff (German Aerospace Center - DLR), Christian Ziach (German Aerospace Center (DLR e.V.)) Presentation: Kai Borchers - Monday, March 4th, 09:50 PM - Jefferson
        20 years after the successful ground deployment test of a (20 m)² solar sail at DLR Cologne, and in the light of the upcoming U.S. NEAscout mission, we provide an overview of the progress made since in our mission and hardware design studies as well as the hardware built in the course of our solar sail technology development. We outline the most likely and most efficient routes to develop solar sails for useful missions in science and applications, based on our developed ‘now-term’ and near-term hardware as well as the many practical and managerial lessons learned from the DLR-ESTEC GOSSAMER Roadmap. Mission types directly applicable to planetary defense include single and Multiple NEA Rendezvous ((M)NR) for precursor, monitoring and follow-up scenarios as well as sail-propelled head-on retrograde kinetic impactors (RKI) for mitigation. Other mission types such as the Displaced L1 (DL1) space weather advance warning and monitoring or Solar Polar Orbiter (SPO) types demonstrate the capability of near-term solar sails to achieve asteroid rendezvous in any kind of orbit, from Earth-coorbital to extremely inclined and even retrograde orbits. Some of these mission types such as SPO, (M)NR and RKI include separable payloads. For one-way access to the asteroid surface, nanolanders like MASCOT are an ideal match for solar sails in micro-spacecraft format, i.e. in launch configurations compatible with ESPA and ASAP secondary payload platforms. Larger landers similar to the JAXA-DLR study of a Jupiter Trojan asteroid lander for the OKEANOS mission can shuttle from the sail to the asteroids visited and enable multiple NEA sample-return missions. The high impact velocities and re-try capability achieved by the RKI mission type on a final orbit identical to the target asteroid‘s but retrograde to its motion enables small spacecraft size impactors to carry sufficient kinetic energy for deflection.
      • 02.1208 Development of a Realistic Set of Synthetic Earth Impactor Orbits Steven Chesley (Jet Propulsion Laboratory), Giovanni Valsecchi (INAF), Siegfried Eggl (University of Washington), Mikael Granvik (University of Helsinki), Davide Farnocchia (Jet Propulsion Laboratory), Robert Jedicke (University of Hawaii) Presentation: Steven Chesley - Thursday, March 7th, 09:20 AM - Amphitheatre
        We present a refined method for creating orbits of fictitious Earth impactors that are representative of the actual impactor population. Such orbits are crucial inputs to a variety of investigations, such as those that seek to discern how well and how early a particular asteroid survey can detect impactors, or to understand the progression of impact probability as an object is tracked after discovery. We will describe our method, which relies on Opik's b-plane formalism, and place it in context with previous approaches. While the Opik framework assumes the restricted three body problem with a circular Earth orbit, our final synthetic impactors are differentially corrected to ensure an impact in the N-body problem of the solar system. We also test the validity of the approach through brute force numerical tests, demonstrating that the properties of our synthetic impactor population are consistent with the underlying Near-Earth Object (NEO) population from which it is derived. The impactor population is, however, distinct from the NEO population, not only by virtue of the proximity of the asteroid orbit to that of the Earth, but also because low encounter velocities are strongly favored. Thus the impacting population has an increased prominence of low inclination and low eccentricity orbits, and Earth-like orbits in particular, as compared to the NEO population as a whole.
      • 02.1209 Characterization of Asteroids Using Nanospacecraft Flybys and Simultaneous Localization and Mapping Mihkel Pajusalu (Massachusetts Institute of Technology), Andris Slavinskis (Tartu Observatory/NASA Ames Research Center) Presentation: Andris Slavinskis - Thursday, March 7th, 09:45 AM - Amphitheatre
        Nanospacecraft could enable detailed characterization of many asteroids in a small timeframe by launching multiple spacecraft simultaneously to visit a large set of targets. To be able to characterize as large of a set of asteroids as possible, however, visits to individual asteroids would be limited to flybys, which would have to be autonomous. As an additional challenge, due to the limitations of nanospacecraft and a massively parallel architecture, Earth-based localization and communication infrastructure, such as the Deep Space Network, cannot be relied upon. We have developed an optical instrument prototype and an image simulation system for autonomous asteroid flybys and 3D multispectral mapping using nanospacecraft. The final system is targeted to fit into a single CubeSat unit (a 10 cm cube) and to have the mass of less than 1 kg. The images are used for structure from motion algorithms to determine the quality of 3D reconstruction to be expected from this mission. We are presenting the instrument design, the simulation system, and the simultaneous localization and mapping system developed for nanospacecraft asteroid flybys.
      • 02.1210 Double Asteroid Redirection Test: The Earth Strikes Back Elena Adams (Johns Hopkins University/Applied Physics Laboratory), Daniel O’shaughnessy (Johns Hopkins University/Applied Physics Laboratory), Matthew Reinhart (Johns Hopkins University/Applied Physics Laboratory), Jeremy John (Johns Hopkins University/Applied Physics Laboratory), Elizabeth Congdon (The Johns Hopkins University Applied Physics Laboratory), Daniel Gallagher (JHU Applied Physics Laboratory), Elisabeth Abel (Johns Hopkins University/Applied Physics Laboratory), Justin Atchison (Johns Hopkins University Applied Physics Laboratory), Zachary Fletcher (), Michelle Chen (Johns Hopkins University/Applied Physics Laboratory), Christopher Heistand (Johns Hopkins Univ Applied Physics Lab (JHU APL)), Evan Smith (Johns Hopkins University/Applied Physics Laboratory), Philip Huang (johns hopkins univieristy applied phyics laboratory), Deane Sibol (Johns Hopkins University/Applied Physics Laboratory), Dmitriy Bekker (Johns Hopkins Applied Physics Laboratory), David Carrelli (Johns Hopkins University/Applied Physics Laboratory) Presentation: Evan Smith - Thursday, March 7th, 10:10 AM - Amphitheatre
        The NASA Double Asteroid Redirection Test (DART) is a technology demonstration mission that will test the kinetic impactor technique on a binary near-Earth asteroid system, Didymos. Didymos is an ideal target, since the 780 m primary, Didymos A, is well characterized, and the 163 m secondary, Didymos B, is sufficiently small to allow measurement of the kinetic deflection. Didymos also represents the population of Near Earth Objects that are the asteroids most likely to pose a near-term threat to Earth. Scheduled to launch in June 2021, the DART spacecraft will autonomously intercept Didymos B in October 2022, altering the orbit period of Didymos B with respect to Didymos A. The impact will occur when the Earth-Didymos range is close enough to allow observation by Earth-based optical and radio telescopes. The spacecraft will be guided to the impact by its on-board autonomous real-time system Small-body Maneuvering Autonomous Real-Time Navigation (SMART Nav). In addition, DART is carrying a 6U CubeSat provided by Agenzia Spaziale Italiana (ASI). The CubeSat will provide imagery documentation of the impact, as well as in situ observation of the impact site and resultant ejecta plume. The development is currently in Phase C, with mission Critical Design Review (CDR) planned for summer 2019. It is a substantial challenge to navigate the DART spacecraft to a hypervelocity impact with the Didymos secondary. The DART spacecraft will carry an ion propulsion system with the NASA Evolutionary Xenon Thruster Commercial (NEXT-C) engine, which provides flexibility in trajectory design to achieve the desired Didymos arrival conditions. The trajectory maximizes the asteroid deflection with an arrival velocity of 6 km/s relative to Didymos-B, while maintaining a proximity to Earth that allows both observation of the impact, and sufficient communication gain to recover imagery of the target upon the approach. Additionally, NEXT-C allows the mission an opportunity to fly by another asteroid and characterize SMART Nav performance seven months prior to its use for the Didymos impact. The DART spacecraft carries 22 m2 solar arrays to generate the ~3.5 kW needed to power the NEXT-C engine. These long arrays introduce substantial flexible body motion to the spacecraft. This motion must be managed carefully to maintain the DART narrow angle camera on the target asteroid, even while performing the necessary autonomous ΔV maneuvers required to intercept the target. Guidance to Didymos B is further complicated by having to switch targets late in the approach, as SMART Nav must target the primary asteroid initially, as the secondary is too small to be resolved by the narrow angle camera until ~1 hour prior to impact. Shadowing of both primary and secondary set by arrival lighting makes it challenging to impact at the center of Didymos B. The spacecraft streams images back to Earth in real time, up until impact.
    • 02.13 Orbital Robotics: On-Orbit Servicing and Active Debris Removal Roberto Lampariello (German Aerospace Center - DLR) & David Sternberg (NASA Jet Propulsion Laboratory)
      • 02.1305 An Approach to Contact Detection and Isolation for Free-floating Robots Based on Momentum Monitoring Francesco Cavenago (Politecnico di Milano), Alessandro Massimo Giordano (), Mauro Massari (Politecnico Di Milano) Presentation: Francesco Cavenago - Wednesday, March 6th, 04:30 PM - Jefferson
        Dealing with physical contact is one of the main challenges that must be faced in order to foster the use of manipulators in on-orbit operations. Several future applications, e.g. on- orbit servicing, will require the robot to operate in close proximity to a target object, or another robot, or an astronaut, potentially. In these conditions, contact situations could arise and they may be intentional, e.g. grasping operation, or accidental, e.g. unforeseen collision. The space robot should be endowed with algorithms to master all these circumstances properly. When a contact occurred, detecting it, understanding which part of the robot is involved and evaluating its intensity is particularly relevant to carry out on-orbit operations successfully. Especially, in this work, contact detection and isolation problems for a free-floating space robot are addressed. An approach based on monitoring the total momentum of the system is proposed. Indeed, in free-floating mode, no force or moment acts on the base and thus the total momentum is preserved. When a contact situation arises, the components of the total momentum change, detecting the event. Moreover, translational and rotational momentum can be exploited to identify the exact contact point. Finally, a possible extension of the approach to robots with base actuation is preliminarily discussed. The performance of the proposed strategies is assessed through numerical simulations considering a free-floating robot composed of a 3 degrees-of-freedom (DOF) arm mounted on a 6DOF moving base.
      • 02.1307 Assembled, Modular Hardware Architectures - What Price Reconfigurability? Christine Gregg (NASA Ames Research Center), Benjamin Jenett (), Kenneth Cheung (NASA - Ames Research Center) Presentation: Christine Gregg - Wednesday, March 6th, 04:55 PM - Jefferson
        Re-usability of space exploration hardware in general is often discussed for its potential to vastly reduce the cost of space operations, and is cited as a potential benefit of on-orbit robotics. But does reconfigurability come at the cost of assembly or performance efficiency? This talk specifically evaluates the potential use of highly modular material systems - such as reversibly assembled cellular composite materials - as the basis for re-configurable exploration hardware. First, a dimensional scaling argument is presented to suggest that systems of all sizes can benefit from mass savings associated on-orbit assembly. Next, we examine the relative energetic cost of various strategies for on-orbit manufacturing (reconfiguration, reuse/recycling, deposition based additive manufacturing, or conventional forming processes) and conclude that investment in mechanically assembled reconfigurable material systems holds the potential for orders of magnitude reduction of energy required for long-term on-orbit manufacturing activities. We propose that discretely assembled cellular materials could serve this purpose, and show that the parasitic mass penalty associated with reversible mechanical connection hardware can be characterized and is well-bounded. Finally, we discuss notional missions at a high level to motivate future detailed analysis and evaluation of various mission architectures.
      • 02.1309 Decentralized Cooperative Localization with Relative Pose Estimation for a Spacecraft Swarm William Bezouska (), David Barnhart (University of Southern California) Presentation: William Bezouska - Wednesday, March 6th, 05:20 PM - Jefferson
        This paper presents a decentralized cooperative localization approach to relative state estimation for a team of spacecraft to estimate inertial position, orientation, velocity, and angular velocity of each spacecraft. The solution uses an Extended Kalman Filter (EKF) running on each spacecraft to estimate the full state of every other spacecraft in the swarm. A Multiplicative EKF is used to address limitations of quaternion representation of attitude; non-quaternion states are estimated by a standard EKF. Each spacecraft is equipped with a gyroscope, a star tracker, and a relative pose measurement sensor. Only pose measurements between spacecraft are shared among the team. Simulation results are provided which demonstrate an improvement in state estimation for the swarm when shared relative pose measurements are incorporated into the filters running on each spacecraft. Estimation performance in various sensing graph configurations is also explored. The methodology and results presented in this paper provide a foundation for future research by introducing the concept of cooperative localization into spacecraft swarm state estimation.
      • 02.1310 Algorithmic Approaches to Reconfigurable Space Assembly Systems Allan Costa (MIT), Amira Abdel Rahman (MIT), Kenneth Cheung (NASA - Ames Research Center), Benjamin Jenett (), Neil Gershenfeld (MIT) Presentation: Allan Costa - -
        In this presentation we describe the problem of assembly of large scale structural systems in space. This task is critical since many space applications can't be deployed in a single task. We describe recent work at NASA in the usage of discrete modular structures for in-space assembly, as well as the usage of small scale robotics that are able to modify and traverse these structures. We summarize two fundamentally different approaches for solving this problems, describing centralized approaches and distributed ones. We discuss fundamental design trades for different computational architectures, such as centralized versus distributed, and present two representative algorithms as concrete examples for comparison. We analyze how those algorithms achieve different objective functions and goals, such as minimization of total distance traveled, maximization of fault-tolerance, or minimization of total time spent in assembly. We compare the two approaches, and show results from simulations and testing procedures to test our hypotheses. Conclusion recommendations are developed on where and when to use each paradigm, as well as implications for physical robotic and structural system design
      • 02.1313 Robust Estimation of Motion States for Free-Floating Tumbling Target Capture Abril Poó Gallardo (German Aerospace Center - DLR), Hrishik Mishra (German Aerospace Center - DLR), Alessandro Massimo Giordano (), Roberto Lampariello (German Aerospace Center - DLR) Presentation: Roberto Lampariello - Wednesday, March 6th, 09:00 PM - Jefferson
        In this paper, we propose a novel extended Kalman filter (EKF) to aid the capture of a free-floating tumbling satellite (Target) with a manipulator-equipped spacecraft (Servicer) in the close-range capture phase. For such a control problem, the interfacing of a fast-sampled robot controller with slow-sampled exteroceptive sensors on the spacecraft causes a performance loss in the robot controller. In order to circumvent this problem, a method is proposed with the main objective of providing fast relative state reconstruction between Target and Servicer. To this end, the proposed EKF estimates the inertial motion states of the Target and the base of the Servicer at a high rate using slow-sampled and noisy exteroceptive measurements, which include relative poses from a camera and a Light Detection And Ranging sensor (LiDAR) and absolute orientation from star/sun trackers. The inherent sensor redundancy provides robustness during sensor occlusion. The state information is combined with the measurements from Inertial Measurement Unit (IMU), forward kinematics (using robot joint encoders) and a priori known transformations to provide fast-sampled estimates of the inertial states. This information is used to reconstruct relative states for feedback control, and furthermore, the Target's tumbling velocity is also estimated for feed-forward. The novelty of the EKF is in the simultaneous estimation of two quaternion states from a composite measurement of both. The robustness of the proposed EKF against parametric uncertainty was validated with 640 Monte-Carlo simulations, a summary of which is presented. Furthermore, the validity of the EKF is demonstrated by using it in closed-loop with a combined controller on Guidance, Navigation and Control Development Environment (GNCDE) software.
      • 02.1314 Perception-Constrained Robot Manipulator Planning for Satellite Servicing Tariq Zahroof (Stanford University), Andrew Bylard (Stanford University), Hesham Shageer (Stanford University), Marco Pavone (Stanford University) Presentation: Marco Pavone - Wednesday, March 6th, 09:25 PM - Jefferson
        Satellite servicing is a rapidly developing industry which requires a number advances in semi- and fully-automated space robotics to unlock many key servicing capabilities. One upcoming mission example is the NASA Restore-L Robotic Servicing spacecraft, which is equipped with two 7-joint robotic manipulators used to capture a satellite and perform a complex series of refueling tasks, including swapping between various end-effector tools stored on board. In this scenario, planning of the manipulator motions must account for a number of constraints, such as collision avoidance and the potential need for uninterrupted visual tracking of objects or of the end-effector. Such complex constraints in a cluttered environment, such as the interface between two spacecraft, are time-consuming to incorporate into hand-designed trajectories. Thus, in this work we present a software tool which uses robot motion planning and path refinement algorithms for automated, real-time computation of near-optimal, collision-free trajectories which satisfy the aforementioned perception constraints. The tool is built on the ROS MoveIt! framework, which can simulate and visualize trajectories as well as seamlessly switch between motion planning and refinement algorithms depending on task requirements. Additionally, we performed experimental campaigns to benchmark a number of available algorithms for performance in handling such perception constraints. Although the framework is applied to a mock-up of Restore-L satellite servicer in this paper, the tool can be applied to any fixed-base manipulator planning scenario with a similar class of constraints.
  • 3 Antennas, RF/Microwave Systems, and Propagation James Hoffman (Jet Propulsion Laboratory) & Farzin Manshadi (Jet Propulsion Laboratory)
    • 03.01 Phased Array Antenna Systems and Beamforming Technologies Abbas Omar (University of Magdeburg) & Glenn Hopkins (Georgia Tech Research Institute) & Janice Booth (AMRDEC Weapons Development and Integration Directorate)
      • 03.01 3.01 Keynote :Magnetic Resonance Imaging RF-Coils as Phased Arrays Abbas Omar Presentation: Abbas Omar - - Cheyenne
        Imaging is constructing a two-dimensional or three-dimensional map of a certain physical property of the object to be imaged. There are different types of imaging, the well-known of which is photography, which maps the object surface optical reflectivity. A second example is acoustic imaging, in which the material density is the object physical property that is mapped. Microwave imaging on the other hand maps the permittivity and conductivity of the imaged object. Magnetic-Resonance Imaging (MRI) basically maps the concentration of the hydro- gen nuclei in the imaged object. Almost all fundamental particles (electrons, protons … etc.) possess a characteristic spin magnetic moment. Applying a strong static magnetic field to an object, results in directing these spins parallel and anti-parallel to the applied magnetic field. This gives rise to two en- ergy states, whose populations are governed by the lows of thermodynamics. If, in addition, an RF field of a certain frequency is properly applied for a certain time, the spins start to pre- cess about the direction of the static magnetic field disturbing the thermodynamic equilibrium. During the process of restoring the thermodynamic equilibrium, the spins radiate an electro- magnetic field which can be received and used for constructing the MR images. The strength of the static magnetic field plays a key role in the quality and resolution of the obtained im- ages. In this talk, the fundamentals of MRI are firstly presented. Technical aspects related to the generation and detection of the RF field are explained. One of these aspects is the design of RF coils capable of generating homogeneous magnetic field (homogeneous illumination) within the object to be imaged. We will discuss applying a number of well-known antenna techniques such as Beam Forming, Butler Matrices, and Rotman Lenses to advanced Mag- netic Resonance Imaging. Special emphases are put on imaging systems utilizing high static magnetic fields for improving resolution.
      • 03.0102 GPU Acceleration for Synthesis of Coherent Sparse Arrays Zachary Baker (Los Alamos National Lab) Presentation: Zachary Baker - Wednesday, March 6th, 10:10 AM - Cheyenne
        The goal of this effort is to change how we think about and build arrays of satellites. Traditionally, synthesis of large, free flying apertures has been proposed by means of metrology or precise measurement and positioning of small satellite collectors. Our approach replaces measurement with ground computations, searching across the range of possible orientations and relative positioning, and direction of travel to precisely align the collection of signals. In this work we demonstrate a proof of concept collection, discuss the upper bounds on achievable accuracy, and discuss our signal processing methodology. Aperture synthesis with free flying vehicles is a challenging problem, but if successful, can provide a variety of capabilities, improving the usefulness of small space assets. Potential capabilities include removing jammers, removing co-channel interference, allowing selective reception, boosting Signal-to-Noise Radio (SNR) through improved directionality and improved aperture size. Additionally, implementing a large aperture with several small collectors increases coverage and survivability. Of course, all this processing effort is a complication over just having a larger satellite. A large aperture requires a large satellite, and a large satellite is more expensive. The Los Alamos National Laboratory's ``Agile Space'' program is built on the idea that many small apertures can provide capability that is distinctly different than traditional, ``big'' space. Replacing a large vehicle with many small, low-cost vehicles allows new capability, including cheap vehicle replacement, flexible missions, and far cheaper development process. The goal of this effort is to achieve ``coherence'' without shared clocks or accurate metrology. For our purposes, “coherence” means that the collected signal phase (carrier plus modulating signal) is aligned within some tolerance, normally within a few degrees. Phase alignment is important, because with aligned phase you can use interference techniques such as beamforming. This paper will include a review of the coherence-through-computation process, and then delve into our new work enhancing both the fundamentals of the algorithm and the time performance. This includes on-GPU execution of the CAF algorithm, on-GPU multi-emitter tracking, and interpolation-based correction adaptation.
      • 03.0103 Retrodirective Phased Array Antennas for Small Satellites Justin Long (University of Alaska Fairbanks), Denise Thorsen (University of Alaska Fairbanks), Obadiah Kegege (NASA Goddard Space Flight Center) Presentation: Justin Long - Wednesday, March 6th, 10:35 AM - Cheyenne
        A high gain retrodirective phased array antenna (RDA) design for CubeSats, with lenient pointing requirements. The presentation will cover the background theory behind the antenna, simulations that show the benefits of the RDA, testing and analysis of major constraints affecting the design, and the system design architecture. A spacecraft design has been funded through the University Nanosatellite Program that will incorporate the prototype system. A phased array antenna can offer high gain and beamforming capabilities to small satellites. Retrodirective capabilities allow the communication system to autonomously determine the direction of an incoming signal without prior knowledge, and form the beam appropriately to achieve maximum gain. The end result is a compact high gain antenna without strict pointing requirements or deployables.
      • 03.0105 General Analysis of Coupled-Element Antenna Arrays Abbas Omar (University of Magdeburg) Presentation: Abbas Omar - Wednesday, March 6th, 11:00 AM - Cheyenne
        A general analysis of antenna arrays with inter-element coupling is presented/revisited. It is shown that the array in this case should be treated as a whole entity, which is characterized by a number of eigenmodes equal to that of the array elements. Such array modes can be independently excited and used for beamforming and steering exactly like the individual elements in the uncoupled case. The analysis adopts a coupled-resonator structure as a model for the array. The related equivalent circuit is derived field theoretically for a fairly general antenna element. Only one-dimensional arrays are considered in details. The generalization to the two-dimensional case is however straightforward. The paper is principally of a fundamental nature with revisited physical insight into the operation of antenna arrays.
    • 03.02 Ground and Space Antenna Technologies and Systems Vahraz Jamnejad (Jet Propulsion Laboratory) & Farzin Manshadi (Jet Propulsion Laboratory)
      • 03.0201 The Multibeam Radar Sensor BIRALES: Performance Assessment for Space Surveillance and Tracking Matteo Losacco (Politecnico di Milano), Pierluigi Di Lizia (Politecnico di Milano), Mauro Massari (Politecnico Di Milano), Germano Bianchi (INAF), Giuseppe Pupillo (INAF - IRA), Andrea Mattana (), Giovanni Naldi (National Institute for Astrophysics), Claudio Bortolotti (), Mauro Roma (), Marco Schiaffino (INAF), Federico Perini (INAF), Luca Lama (), Alessio Magro (University of Malta), Denis Cutajar (University of Malta), Josef Borg (University of Malta), Marco Reali (Italian Ministry of Defense - Italian Air Force), Walter Villadei () Presentation: Matteo Losacco - -
        This presentation shows an analysis of the performance of the novel multibeam radar sensor BIRALES. The tailored orbit determination algorithm is described, and the results obtained with both numerical simulations and real observation campaigns are offered.
      • 03.0204 Distributed Swarm Antenna Arrays for Deep Space Applications Marco Quadrelli (Jet Propulsion Laboratory), Saptarshi Bandyopadhyay (Jet Propulsion Laboratory), Richard Hodges (Jet Propulsion Laboratory), Victor Vilnrotter (Jet Propulsion Laboratory) Presentation: Saptarshi Bandyopadhyay - Wednesday, March 6th, 08:55 AM - Cheyenne
        NASA has a need for deep space high data rate transfer, and at the same time for multifunctional subsystem integration in order to reduce the mass, volume, and power of autonomous assets being sent to targets of planetary exploration. This capability will improve entire classes of future JPL missions, with benefits to key challenges in multiple directorates. Combining transmit and receive architectures would also benefit science. A large swarm could be assembled in multiple launches, possibly as part of launches sent in preparation for a future human exploration of Mars. On-going miniaturization in power electronics would make a compelling business case. The main conclusion of this study is that a high data rate downlink swarm array at Mars is feasible. Approximately 30 MarCO CubeSats can achieve MRO-level performance, and ~100 MarCO CubeSats achieve 10X MRO-level performance. Spacecraft could be incrementally added to the swarm, with each launch. Therefore, no dedicated launch would be necessary. Future work includes the further development of metrology options: current RF and Optical metrology options are for big spacecraft (100-kg class); and we need to further develop metrology options for small spacecraft. Also, improved time synchronization options need to be developed, as they closely relate to the metrology.
      • 03.0207 Automated Ground Station Design for an Amateur LEO Satellite System Lipika Garg (Manipal University), Atharva Kand (Manipal University), Malhar Pradhan (Manipal Institute Of Technology), Abhishek Agarwal (Manipal Institute of Technology) Presentation: Lipika Garg - -
        This paper describes the RF architecture and automated functioning of the Ground Station of a 2U nano-satellite. The satellite utilizes the UHF band for payload transmission and the VHF band for both satellite uplink as well as beacon downlink. Hence, the station has been set up to have reception capability for the VHF and UHF amateur radio frequency bands. The ground station hardware architecture has been described along with the specification of the components used. The intent behind the automation of the ground station is to enable data collection and satellite tracking during off hours. At the ground station, Doppler shift correction and the control of the Yagi Uda antennas via the rotor control during a satellite pass is automated for continuous data reception. The radio, chip transceiver, and rotor control setup are all interfaced to a dedicated PC via a UART line. The PC also hosts third-party software required for reception and decoding. This includes the satellite tracking software, audio recorder, and decoder. The specification of the software above and their automation capabilities have been discussed. The ground station functioning was verified by receiving and decoding beacon data from other nano- satellites transmitting on the same amateur radio frequency bands, at heights comparable to the LEO height. The paper also includes the link budget calculations and the subsequent link margin determination. The reception of the beacon and raw data bits from the satellite using a Radio and CC1101 transceiver chip respectively and its subsequent decoding on the computer has been described. It includes all necessary calculations and diagrams.
    • 03.03 RF/Microwave Systems James Hoffman (Jet Propulsion Laboratory)
      • 03.0301 Signal Recovery and Detection of Certain Wideband Signals Using Multiple Low-Rate ADCs Michael Johnson (Naval Postgraduate School) Presentation: Michael Johnson - Wednesday, March 6th, 11:25 AM - Cheyenne
        The focus of this paper is to develop an innovative approach to receiver design for wideband signals with resonant frequency components. It is known that there are certain wideband signals that occupy quite large bandwidths but may have dominant amplitudes in certain frequency bands. Many studies have applied signal processing techniques to high bandwidth signals to lower the sampling rate. Compressive sensing (CS) is one such method and has been shown to succeed but only in a special case. The CS approach requires the signal to be sparse in some domain. In this work, we focus on signal classes where previously developed reconstruction and detection techniques may fail. In other words, we focus on signals that have large bandwidths with dominant frequency components, but are not necessarily sparse in time. We show that these signals can be effectively sampled by a lower sampling rate compared to what is required by the Nyquist-Shannon sampling theorem. In our design resonant frequency components are channelized into separate receiver paths (subchains) and sampled at a lower sampling rate than is required for the entire wideband signal. Both the signal and noise energy are reduced, although not equally, by the receiver. Noise energy outside of the selected bands is greatly attenuated while these dominant bands are filtered into subchains for processing. It is shown that the signal’s sum squared error (SSE) improves and the probability of detection performance experiences little or no degradation as the effective noise power is attenuated by the proposed method.
      • 03.0305 Linearisation of SATCOM Power Amplifiers Suat Ayoz (Honeywell International, Inc.), Jamal Haque (Honeywell) Presentation: Jamal Haque - Wednesday, March 6th, 11:50 AM - Cheyenne
        The ultimate objective of this work was to develop a demonstrator of a highly efficient, GaN based, linearised, passively cooled solid-state power amplifier (SSPA) for avionic SATCOM terminals operating in L-band. The SSPA should provide sufficient output power to comply with all SATCOM classes in all installation options, meet all in-band and out-of-band distortion limits such as error vector magnitude (EVM) and spectral regrowth, and guarantee reliable operation for 1M-hours. The contract, undertaken with European Space Agency (ESA) funding, mandates the use of Gallium Nitride (GaN) technology and power amplifier linearisation techniques to maintain high efficiency, while operating in a linear fashion. The SSPA needs to meet all requirements without any forced-air cooling. The project has been completed successfully, achieving the 47% PAE target, while amplifying a single-carrier test waveform (Inmarsat R20T4.5X type waveform with 16-QAM modulation and 151.2kS/s symbol rate) to ~15W nominal / ~65W peak power level. Digital pre-distortion (DPD) linearisation was used to achieve <2% EVM and >10dB margin in spectral regrowth measured against the ETSI (European Telecommunication Standards Institute) and Inmarsat channel masks at all offset frequencies. Passive cooling was demonstrated with GaN junction temperature not exceeding 150°C (absolute maximum rating 275°C) and mean-time-to-failure (MTTF) reliability of more than 10M hours.
    • 03.04 Radio Astronomy and Radio Science Mark Bentum (Eindhoven University of Technology) & Melissa Soriano (Jet Propulsion Laboratory)
      • 03.0403 The First Two Years of Juno Spacecraft Astrometry with the Very Long Baseline Array Dayton Jones (Space Science Institute), William Folkner (), Ryan Park (), Christopher Jacobs (JPL), Jonathan Romney (National Radio Astronomy Observatory), Vivek Dhawan (National Radio Astronomy Observatory) Presentation: Dayton Jones - Thursday, March 7th, 08:30 AM - Cheyenne
        The Very Long Baseline Array (VLBA) is a ten-antenna radio interferometer with baseline lengths up to 8000 km. It can provide astrometric measurements of spacecraft orbiting planets and other objects in our solar system with sub-nrad precision (5 nrad = 1 milli-arcsec). These measurements can be used to create a time series of positions for solar system objects in the inertial International Celestial Reference Frame, which in turn can be combined with other data to refine the planetary ephemeris. An accurate solar system ephemeris is critical for interplanetary spacecraft navigation, dynamical studies and tests of gravitational theories, the analysis of pulsar timing observations, predictions of transits, eclipses, and occultations, and other applications. We are using VLBA observations of the Juno spacecraft in orbit about Jupiter to provide accurate positions for the Jupiter system barycenter for the ephemeris development group at the Jet Propulsion Laboratory, using observing and data reduction techniques developed for similar observations of the Cassini spacecraft while it orbited Saturn from 2004 until 2017. The VLBA observations of Cassini helped to improve the accuracy of Saturn's orbit by nearly an order of magnitude, and we expect that our observations of Juno will produce a similar improvement in our knowledge of Jupiter's orbit. Astrometric positions are particularly useful in constraining the orientation (inclination and longitude of ascending node) of an orbit, while range measurements are most useful in constraining the semi-major axis and ellipticity. Juno's orbit around Jupiter has a longer period than initially planned due to a concern about the spacecraft main engine. The resulting extended mission duration will improve our constraints on Jupiter's orbit inclination beyond that originally expected. Our VLBA observations of Juno are scheduled during approximately every third or fourth perijove pass. During these times the Juno spacecraft is continuously tracked by the Deep Space Network and the most precise solutions for the orbit of Juno about Jupiter are available. A good spacecraft orbit solution is needed to transfer our spacecraft sky positions to planet system barycenter positions. VLBA astrometry of planetary spacecraft has previously been applied to Mars orbiting space-craft, and will also be used during the OSIRIS-REx mission to improve the accuracy of the orbit of the potentially hazardous asteroid Bennu.
      • 03.0404 Modeling of Venus Atmospheric RF Attenuation for Communication Link Purposes Cornelis Du Toit (AS and D, Inc.), David Everett (NASA - Goddard Space Flight Center), Ralph Lorenz (Johns Hopkins University/Applied Physics Laboratory) Presentation: Cornelis Du Toit - Thursday, March 7th, 08:55 AM - Cheyenne
        The presentation will describe a method for modelling microwave propagation and signal attenuation along an electromagnetic ray linking a spacecraft with a descent probe within the atmosphere of Venus. Attenuation in the Venusian atmosphere is governed by energy absorption and defocusing effects along the path of propagation. Empirical models of the relevant atmospheric properties affecting these will be described and how these are used to determine the refracted ray path by way of an efficient numerical integration procedure, coupled with a fast converging iterative algorithm. Emphasis is placed on S-band frequencies, but the method and formulations are applicable up to about 10GHz. Rather than describing the atmospheric loss modelling and methods in detailed mathematical terms as was done in the paper, the rationale behind the methods will be explained qualitatively using visual aids.
      • 03.0405 Radio Science at Jupiter: Past Investigations, Current Results, and Future Prospects Dustin Buccino (Jet Propulsion Laboratory), Marzia Parisi (Jet Propulsion Laboratory), Yu Ming Yang (NASA Jet Propulsion Lab), Daniel Kahan (), Kamal Oudrhiri (Jet Propulsion Laboratory) Presentation: Dustin Buccino - Thursday, March 7th, 09:20 AM - Cheyenne
        Over the last 40 years, several missions of the National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) have explored the largest planet in the solar system, Jupiter. Radio Science has been a key component of each mission to the planet, where radio signals between the spacecraft and the Earth-based observing antennas have been utilized to determine the physical properties of Jupiter and its moons, their atmospheres, ionospheres, and gravity fields. Jupiter has been visited by nine spacecraft since the dawn of planetary robotic exploration and in each case Radio Science has been a key instrument in analyzing the Jovian environment. In preparation for Juno's current analysis of Jupiter and future missions to the system, this work surveys all past radio science investigations at Jupiter and discusses their implications on the future of Radio Science at Jupiter.
      • 03.0406 The Radio Environment for a Space-based Low-frequency Radio Astronomy Instrument Mark Bentum (Eindhoven University of Technology), Pieter Van Vugt (University of Twente), Albert Boonstra (ASTRON) Presentation: Mark Bentum - Thursday, March 7th, 09:45 AM - Cheyenne
        Opening the last frequency window for radio astronomy in the sub - 30 MHz region includes a few challenges. First of all, at frequencies below 30 MHz the Earth’s ionosphere severely distorts radio waves originating from celestial sources, and it completely blocks radio waves below 10 MHz. This means that radio astronomy and astrophysics below 30 MHz is best conducted from space. Secondly, the radio spectrum below 30 MHz is filled with very strong transmitters signals, making it difficult to do Earth-based radio observations. Most low frequency space-based radio telescope studies and initiatives aim to place a swarm of satellites far away from the Earth’s radio interference. Deployment location options include a lunar orbit, the Earth-Moon Lagrangian point behind the Moon (L2), and an Earth leading or trailing location. There is little knowledge about the radio frequency interference (RFI) environment outside the ionosphere. However, to determine the location of the radio telescope, it is important to understand the radio environment at possible deployment locations. In this paper we will address the radio environment for space-based low frequency radio astronomy. To do so, we will use the data of the WIND/WAVES instrument. The data from November 1994 till November 2016 is used for this analysis. Analysing the data results in addressing the best location for a space-based low frequency radio telescope.
      • 03.0408 Correlators for Synthetic Apertures in Space Alexander Hegedus (University of Michigan), Melissa Soriano (Jet Propulsion Laboratory), Andy Kurum (), Justin Kasper (University of Michigan) Presentation: Alexander Hegedus - Thursday, March 7th, 10:10 AM - Cheyenne
        In this paper we analyze existing technology and simulate possible work flows to find the best hardware and data processing strategies for the position solving and correlation steps of space based radio arrays at various scales. Such arrays are composed of many free flying spacecraft, and accurate knowledge of their relative positions is necessary for proper data analysis. By using signals from existing Global Navigation Satellite System (GNSS) satellites, each individual spacecraft may record data that can be used to solve for precise orbit determination (POD) solutions to determine the relative propagation delays between each spacecraft pair. Any errors in the position are translated into phase error of the complex correlation data. The acceptable limits of error in position before harming the localization of the radio array are tested, using localization performance of SunRISE as a test case. This work help sets requirements for future space based arrays, particularly the quality of GNSS signal needed on each spacecraft as well as correlator capabilities. It is found that there are several feasible hardware and software combinations available today that could constitute a space based array, and recommendations are provided on which combinations would be well suited for various correlation strategies. The analysis done here also looks further to the future, finding hardware and software combinations that will enable even larger and more powerful arrays. We find that for arrays larger than a certain number (6 for our simple spacecraft cost model), the most cost effective strategy with DSN communication switches from every ship transmitting it's own data to the ground, to having a mothership with a more powerful Ka-band transmission antenna sending every ship's data down for ground based correlation. These price analyses provide a starting point for making informed design choices of larger future arrays.
      • 03.0409 The Sun Radio Interferometer Space Experiment (SunRISE) Mission Concept Justin Kasper (University of Michigan), Joseph Lazio (Jet Propulsion Laboratory) Presentation: Joseph Lazio - Thursday, March 7th, 10:35 AM - Cheyenne
        he Sun Radio Interferometer Space Experiment (SunRISE) would provide an entirely new view on particle acceleration and transport in the inner heliosphere by creating the first low radio frequency interferometer in space to localize heliospheric radio emissions. By imaging and determining the location of decametric-hectometric (DH) radio bursts from 0.1 MHz–25 MHz, SunRISE provides key information on particle acceleration mechanisms associated with coronal mass ejections (CMEs) and the magnetic field topology from active regions into interplanetary space. Six small spacecraft, of a 6U form factor, would fly in a supersynchronous geosynchronous Earth orbit (GEO) orbit within about 10 km of each other, in a passive formation, and image the Sun in a portion of the spectrum that is blocked by the ionosphere and cannot be observed from Earth. Key aspects that enable this mission concept are that only position knowledge of the spacecraft is required, not active control, and that the architecture involves a modest amount of on-board processing coupled with significant ground-based processing for navigation, position determination, and science operations. Mission-enabling advances in software-defined radios, GPS navigation and timing, and small spacecraft technologies, developed and flown over the past few years on DARPA High Frequency Research (DHFR), the Community Initiative for Continuing Earth Radio Occultation (CICERO), and the Mars Cube One (MarCO) missions, have made this concept finally affordable and low-risk. The SunRISE concept involves utilizing commercial access to space, in which the SunRISE spacecraft would be carried to their target orbit as a secondary payload in conjunction with a larger host spacecraft intended for GEO. The Phase A study on the SunRISE mission concept was completed in 2018 July. This paper presents a summary of the concept study. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
      • 03.0410 The Data Processing Pipeline and Science Analysis of the Sun Radio Interferometer Space Experiment Alexander Hegedus (University of Michigan), Justin Kasper (University of Michigan), Ward Manchester (University of Michigan), Andrew Romero Wolf (Jet Propulsion Laboratory), Joseph Lazio (Jet Propulsion Laboratory) Presentation: Alexander Hegedus - Thursday, March 7th, 11:00 AM - Cheyenne
        The Earth’s Ionosphere limits radio measurements on its surface, blocking out any radiation below 10 MHz. Valuable insight into many astrophysical processes could be gained by having a radio interferometer in space to image the low frequency window, which has never been achieved. One application for such a system is observing type II bursts that track solar energetic particle acceleration occurring at Coronal Mass Ejection (CME)-driven shocks. In this work we create a data processing pipeline for the pathfinder mission SunRISE, a 6 CubeSat interferometer to circle the Earth in a GEO graveyard orbit, and evaluate its performance in localizing type II bursts with a simulated CME. Traditional radio astronomy software is hard coded to assume an Earth based array. To circumvent this, we manually calculate the antenna separations and insert them along with the simulated visibilities into a CASA MS file for analysis. We model the response of different array configurations over the 25 hour orbit, combining an ephemeris for the Sun with simulated recovered positions of spacecraft using GPS localization to get the array geometry into the correct frame for processing. We include realistic thermal noise dominated by the galactic background at these low frequencies, as well as new sources of phase noise from positional uncertainty of each spacecraft. To create realistic virtual type II input data, we employ a 2-temperature MHD simulation of the May 13th 2005 CME event, and superimpose realistic radio emission models on the CME-driven shock front, and propagate the signal through the simulated array. Data cuts based on different plasma parameter thresholds (e.g. de Hoffman-Teller velocity and angle between shock normal and the upstream magnetic field) are tested to get the best match to the true recorded emission. We test simulated trajectories of SunRISE and image what the array recovers, comparing it to the virtual input, finding that SunRISE can resolve the source of type II emission to within its prescribed goal of 1/3 the CME width more than 99% of the time with 5 or 6 spacecraft, and 97.5% of the time with 4 spacecraft.
      • 03.0411 Development of an Ultra-Wideband Receiver Package for the Next Generation Very Large Array Jose Velazco (Jet Propulsion Laboratory) Presentation: Jose Velazco - Thursday, March 7th, 11:25 AM - Cheyenne
        The next-generation Very Large Array (ngVLA), is a concept for a radio astronomical interferometric array that will provide large improvements in sensitivity and angular resolution over existing telescopes such as the Jansky Very Large Array (JVLA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The ngVLA will operate in the 1.2 to 116 GHz frequency range and its design is aimed at reducing operational and maintenance costs. The concept includes about 214 18-m reflector antennas and baselines up to 1000 km with a dense core on few-km scales for high surface brightness imaging, centered at the current JVLA site in New Mexico. It is envisioned that the ngVLA will employ several receivers to cover the 1.2 to 116 GHz frequency range. At the Jet Propulsion Laboratory, we have implemented a single wideband receiver package that could cover the 8 to 48 GHz frequency range of the ngVLA. The current JVLA covers this frequency range employing five distinct receiver packages. We estimate that reducing the number of receiving systems required to cover the full frequency range should reduce operating costs. The receiver package we developed consists of a quad-ridge feed horn, low-noise amplifiers (LNA), and a down-converter to analog intermediate frequencies. Both the feedhorn and the LNA are cryogenically cooled. In order to simplify assembly and operating costs, we pursued a simple and compact receiver package design. Key features of this design are a 6:1 frequency ratio, 10-20 dB gain, quad-ridge feedhorn with dielectric loading and a compact cryogenic receiver with a noise temperature of no more than 30 K at the low end of the band. We pursued two wideband 8–48 GHz LNA MMIC designs, the first using 70-nm gallium arsenide, metamorphic high-electron-mobility-transistors (HEMT), and the second using 35-nm indium phosphide HEMTs. The down-converter stage translates the 8-48 GHz input range to an intermediate frequency range of 0-8 GHz with ~20 dB sideband rejection between the upper and lower sideband IF outputs. In this paper, we will report the results obtained, measured gain and noise temperature, with the entire 8-48 GHz receiver package, including the feed, LNA and down-converter.
      • 03.0412 A Common Platform for DSN Receiver Development Andre Jongeling (Jet Propulsion Laboratory) Presentation: Andre Jongeling - Thursday, March 7th, 11:50 AM - Cheyenne
        NASA's Deep Space Network is currently updating a number of sub systems within the Signal Processing Centers at its Deep Space Communication Complexes in order to modernize aging equipment in the downlink receivers for telemetry, tracking, radio science, and radio astronomy. To reduce development costs and increase commonality among these traditionally custom-built receivers, the implementation team has developed a flexible architecture built primarily around commercial off-the-shelf hardware compliant with the Micro Telecommunications Computing Architecture (uTCA) specification and commercial high speed 10Gbit Ethernet switches. Custom firmware and software are being developed to perform the required signal processing functions needed to replace the legacy systems in a phased implementation approach which establishes a new digital Intermediate Frequency (IF) signal distribution system first, followed by implementations of various receiver functions as dictated by need. The first of these new receivers, the Open Loop Receiver, will come online in the Fall of 2018. A description of the new architecture, referred to as the “Common Platform”, will be provided followed by an overview of the phased implementation approach and initial OLR performance results.
    • 03.05 Miniaturized RF/Microwave Technologies Enabling Small Satellite and UAV Systems James Lyke (Space Vehicles Directorate) & Dimitris Anagnostou (Heriot Watt University)
      • 03.0502 Propagation Analysis in Support of Wireless Spacecraft Capability Yu Ming Yang (NASA Jet Propulsion Lab), Norman Lay (Jet Propulsion Laboratory), Daniel Cho (NASA Jet Propulsion Lab), Ryan Rogalin (NASA Jet Propulsion Lab), Clayton Okino (Jet Propulsion Laboratory), Arby Argueta () Presentation: Yu Ming Yang - -
        Wireless technologies have been widely applied in many communication systems on Earth to enhance the transmission data rate, improve the receiving signal-to-noise-ratio (SNR), and increase the channel capacity. For flight mission and spacecraft design, reliable wireless systems will expand the scientific applications and research opportunities of planetary explorations. To retire key risks to use of wireless technologies in spacecraft design and space applications, in this research, we analyze its capability and propagation in the test and operational environments including thermal chamber and on-board of a rover at JPL Mars yard. The software-based wireless system consists a transmitting antenna, two receiving antennas, and a software-based defined radio, which enable to transmit and receive multiple frequency band wireless signals with different modulations and a flexible data rate. Here, we summarize the signal propagation analysis of different test and operational scenarios. The propagation analysis demonstrates that the design of two receiving antennas provides about 20 dB improvement comparing to the single-antenna result. Additionally, the chamber test result shows significant multipath effects observed from the data collected from the two scenarios: 1) transmitting and receiving antennas are inside of the chamber, and 2) the insidechamber receiving antennas receive signals from the outside-chamber transmitter. The statistical analysis of the Mars yard test indicates that signal power has relatively small standard deviation for the scenario that transmitting and receiving antennas are aligned in the line of sight direction with a distance. The standard deviations increase for other scenarios that transmitter is set on rover’s wheel, and receiving antennas are on the top of the rover probably due to multipath effects. The investigation of propagation analysis will be beneficial to a design of a reliable wireless system toward the development of the spacecraft wireless networks in support of NASA’s future flight missions (such as planetary aerobots, rovers, and spacecraft).
      • 03.0503 Additive Manufacturing of RF Metal-Insulator-Metal (MIM) Capacitors on Flexible Substrate Abu Md Numan Al Mobin (South Dakota School of Mines and Technology), Jacob Petersen (South Dakota School of Mines and Technology), Mingrui Liu (South Dakota School of Mines and Technology), William Cross (South Dakota School of Mines and Technology), Jon Kellar (SD School of Mines and Technology), Grant Crawford (South Dakota School of Mines and Technology), Jennifer Jordan (NASA - Glenn Research Center), George Ponchak (NASA Glenn Research Center) Presentation: Abu Md Numan Al Mobin - Thursday, March 7th, 11:00 AM - Amphitheatre
        In this study, we will present the potential for complete additive manufacturing of MIM capacitors using an OptomecTM M3D Aerosol jet printing. The challenges of printing MIM capacitors are investigated and possible solutions are offered. To print the capacitors, both conductive and dielectric inks were formulated. Two capacitors of nominal areas 0.25 and 0.5625 mm^2 are presented to show the temperature dependence of the normalized capacitance and conductance. It is observed that the normalized capacitance decreases with temperature until 75 °C, at which point it stabilizes. The measured conductance shows that these capacitors have low leakage current, which is expected. In addition, the RF performance, maximum operating voltage, adhesion test, and temperature cycling were performed and will be presented.
      • 03.0505 Solar and Lunar Calibration for Miniaturized Microwave Radiometers Angela Crews (Massachusetts Institute of Technology), William Blackwell (MIT Lincoln Laboratory), Kerri Cahoy (Massachusetts Institute of Technology), Robert Leslie (), Michael Grant (NASA - Langley Research Center) Presentation: Angela Crews - Thursday, March 7th, 11:25 AM - Amphitheatre
        Miniaturized microwave radiometers deployed on nanosatellites in Low Earth Orbit (LEO) are now demonstrating the ability to provide science-quality weather measurements, such as the 3U Micro-sized Microwave Atmospheric Satellite-2A (MicroMAS-2A). The goal of having cost-effective miniature instruments distributed in LEO constellations is to improve temporal and geospatial coverage. The Time-Resolved Observations of Precipitations structure and storm Intensity with a Constellation of Smallsats (TROPICS) is a constellation of six 3U CubeSats, based on MicroMAS-2A, scheduled to launch no earlier than 2020. Each CubeSat hosts a scanning 12-channel passive microwave radiometer. TROPICS will improve temporal resolution to less than 60 minutes compared to larger satellites in polar orbit, such as NOAA-20 which hosts the Advanced Technology Microwave Sounder (ATMS) and has a revisit rate of 7.6 hours. [1] The improved refresh rate will provide high value observations of inner-core conditions for tropical cyclones [2]. In order to effectively use miniaturized microwave radiometers on small satellites such as MicroMAS-2A and TROPICS operationally, new approaches to calibration are needed to achieve state-of-the-art performance. Calibration on nanosatellite platforms present new challenges, as standard blackbody targets are too bulky to fit on 3U CubeSats. Instead, internal noise diodes are used for calibration, with long-term drifts measured on the order of 0.2% to 3.0% (approximately 0.4 K to 6.0 K) [4]. Blackbody calibration targets such as used on ATMS have 0.14 K error or better for warm calibration [3]. In order to provide state of the art calibration for CubeSats, methods must be developed to trend and correct noise diode drift. We develop a new way to continuously calibrate CubeSat constellations, such as TROPICS, by incorporating frequent and periodic solar and lunar intrusions as an additional source of information to counter noise diode drift. These solar and lunar intrusions also occur for existing satellites hosting microwave radiometers in polar orbits, but are much more infrequent than for the scanning payload on the TROPICS constellation, and are typically treated as an observational and calibration limiting constraint. The higher occurrence rate of intrusions for TROPICS motivates the novel idea of using the intrusions to support calibration. An algorithm is developed to compare expected effective brightness temperature from solar and lunar measurements to actual measured brightness temperatures. Future work includes developing a detailed error budget for the algorithm and testing the algorithm using actual sun and moon measurements taken by MicroMAS-2A and ATMS. In this paper we discuss background information, provide our approach, and show initial results.
      • 03.0506 A Novel Reconfigurable GaN Based Fully Solid-State Microwave Power Module Rainee Simons (NASA - Headquarters) Presentation: Rainee Simons - Thursday, March 7th, 11:50 AM - Amphitheatre
        Presentation Summary: The paper presents as a proof-of-concept the design, integration, and performance of a novel reconfigurable, S-/X-band GaN MMIC based, fully solid-state microwave power module (SSMPM) with a view to miniaturize the overall RF system. The characterization of the individual components as well as the end-to-end performance of each of the S-band and X-band chains of the SSMPM are presented. These results indicate that the S-band CW chain can deliver Psat of 39 dBm (8 W) for TT&C, the X-band CW chain can deliver Psat of 46 dBm (40 W CW) for telecommunications, and the X-band pulsed chain without the pre-amplifiers can deliver Psat of >50 dBm (>100 W Pulsed) for radar applications. In applications that require very high power, waveguide based unequal power divider/combiner can be utilized. Our link budget calculations indicate that the SSMPM with Psat = 40 W when coupled to a 10 cm X-band transmit antenna on a low Earth orbiting (900 km) satellite can close a 1 Gbps (QPSK) data downlink to a 1 m receive antenna on ground with 3 dB margin. Leveraging upon compound semiconductor devices and novel materials technology will enable the monolithic heterogeneous integration of GaN plus CMOS for realization of a compact SSMPM. The above results indicate that a single SSMPM is capable of being dynamically reconfigured to serve multiple roles such as an amplifier for TT&C, telecommunications, and radar onboard future Earth and planetary exploration spacecrafts. As a final note, GaN HEMT based X-band power amplifiers when tested under conditions in low Earth orbit during a five-year mission, have shown to be tolerant to a total ionizing dose of 20k rads when placed inside a 2 mm thick aluminum shielding enclosure.
  • 4 Communication & Navigation Systems & Technologies Phil Dafesh (Aerospace Corporation) & Shirley Tseng (Tseng LLC)
    • 04.01 Evolving Space Communication Architectures Shervin Shambayati (SSL)
      • 04.0101 Navigation Tracking with Multiple Baselines Part I: High-Level Theory and System Concepts Kar Ming Cheung (Jet Propulsion Laboratory), Charles Lee (Jet Propulsion Laboratory) Presentation: Kar Ming Cheung - Thursday, March 7th, 04:30 PM - Amphitheatre
        Delta Differential One-Way Ranging (DDOR) and Same Beam Interferometry (SBI) are deep space tracking techniques that use two widely separated ground antennas, known as a baseline, to simultaneously track a transmitting spacecraft to measure the time difference between signals arriving at the two stations. Errors are introduced into the delay measurements when the radio waves pass through the solar plasma and the Earth’s atmosphere, and also due to clock bias and clock instability of the ground stations. These errors can be eliminated or calibrated by tracking a quasar in the angular vicinity of the spacecraft (DDOR), or by tracking another close-by spacecraft whose trajectory/orbit is accurately known (SBI). Both DDOR and SBI uses this double-differencing of signal arrival time to eliminate the aforementioned error sources, and to generates highly accurate angular measurements with respect to the baseline. In this paper, we consider simultaneous SBI of two or more baselines that share one common ground station. We show that under certain condition, precise pointing vector between the common ground station and the spacecraft can be computed using simultaneous DDOR measurements from the two baselines. When there is another spacecraft in the vicinity of the first spacecraft, precise pointing vector of the second spacecraft can be derived from the simultaneous SBI measurements. Also, precise angular distance between the two spacecraft can be computed in real-time. We expect these new data types could enhance ground antenna pointing, and deep space spacecraft trajectory estimation and orbit determination. This technique can have near-Earth applications. We describe a system concept that detects and locates dead and non-cooperative spacecraft in the Geostationary Orbit (GEO). This can be done by making use of an existing GEO satellite with accurately known location as a reference, and/or by placing a dedicated “reference” spacecraft into an eccentric geosynchronous orbit over a region of interest (e.g. above North America). By adjusting the orbit, the “reference” spacecraft can sweep through the sky back-and-forth in the vicinity of the GEO over the region. In this way, the reference spacecraft can be close to any “static” GEO targets along its path. Using the multi-static radar approach, the ground transmitting radar illuminates both the reference and target spacecraft, and the ground receiving radars measure the different time-delays of signal arrival. Applying a variant of the aforementioned simultaneous SBI scheme, the time-delay measurements can be used to compute the precise relative position of the target spacecraft with respect to the reference spacecraft, whose position can be accurately estimated using the weak Global Positioning Satellite (GPS) signals.
      • 04.0104 Telecommunication System Architecture for Low Earth Orbit Nano Satellites Mission Support Kavya Shree (PES University) Presentation: Kavya Shree - Thursday, March 7th, 04:55 PM - Amphitheatre
        People Education Society University (PESU), a leading technical institution in Karnataka state of India, has been encouraging student community to learn space technology by providing opportunity to students to design and build nano satellites. Nano satellites are small satellites weighing between 1 kg and 10 kg. They are low cost and provide unique benefits compared to traditional satellites. One of the major concern in developing a nano satellite is the design of remote communication framework to suit the particular mission requirement. Designing a secured and high speed data transfer communication framework over a harsh remote environment for a nano satellite in Low Earth Orbit postures many difficulties and challenging problems. The critical design constraints in a student satellite are Satellite Dynamics, Communication Resource Utilization, Look Angle Geometry, Attenuation, Interference, Small Size, Reliable Communication. During the design of an optimum remote communication framework, these design constraints must be addressed. As a part of this, PISAT a student nano satellite was designed and developed at PES University. VHF/UHF frequency bands, normally used for nano satellites designed for academic interest, have a limitation with information rate thereby limiting the payload and also affected by high noise and interference. Hence, the PISAT satellite is configured in the standard S-band for Telemetry Tracking & Command (TT&C) support. PISAT is a three axis stabilized imaging nano satellite weighing 5 kg and having cuboid structure with S-band RF Communication System. An earth station is a vital element in the satellite communication network. A satellite has to be monitored and controlled from an earth station in addition to receiving payload data for further processing. A fully-fledged ground station has been commissioned for TT&C support in the University campus. Performance check for the completed design was carried out and it was found satisfactory. PISAT was successfully launched into the intended polar sun synchronous orbit at 670 km altitude on 26th Sep 2016 by Indian Space Research Organisation (ISRO) using the PSLV-C35 Rocket. PISAT was successfully tracked from PES Satellite Control Facility (PSCF) during visibility. PISAT was successfully tracked from PSCF during visibility. Communication was established with PISAT. Successful reception of telemetry data and transmission of telecommands from PSCF to PISAT was achieved.
      • 04.0105 RESINATE – an RF and Optical Testbed Craig Kief (COSMIAC at UNM), James Lyke (Space Vehicles Directorate), Don Fronterhouse (PnP Innovations, Inc), Matthew Hannon (COSIMAC University of New Mexico), Robert Richard (Acme), Mayer Landau (), Christian Peters (Air Force Research Laboratory), Derek Buckley (USAF), Zachary Bergstedt (USAF) Presentation: James Lyke - Thursday, March 7th, 05:20 PM - Amphitheatre
        The Resilient Network Advanced Testbed (RESINATE) is a robust RF and Optical testbed for performing research and characterization testing on RF and optical systems communication systems. RESINATE is located in Albuquerque, NM and consists of a series of software transceivers at the 4.5GHz range, free space laser transceivers running over a 24km slant path, and a satellite ground station with a three-meter S-band dish. RESINATE is being used to study both RF and FSO links along with innovative disruption tolerant networking approaches integrating space and ground systems.
    • 04.02 Communication Protocols and Services for Space Networks Shervin Shambayati (SSL)
      • 04.0201 A Delay Tolerant Networking-based Approach to a High Data Rate Architecture for Spacecraft Alan Hylton (NASA), Daniel Raible (NASA Glenn Research Center), Gilbert Clark (Ohio University) Presentation: Alan Hylton - Sunday, March 3th, 09:25 PM - Amphitheatre
        We will discuss our efforts to realize high-speed delay tolerant networking. This will include our approach, our plans to test a system on the International Space Station, and our current benchmarks and studies towards the ISS implementation.
    • 04.04 Relay Communications for Space Exploration Charles Edwards (Jet Propulsion Laboratory) & David Israel (NASA - Goddard Space Flight Center)
      • 04.0401 NASA’s Operational Optical Communications Relay Betsy Park (NASA - Goddard Space Flight Center) Presentation: Betsy Park - Monday, March 4th, 09:00 PM - Amphitheatre
        NASA’s Space Communications and Navigation (SCaN) program is creating an operational optical communications network to complement its current radio frequency (RF) networks. NASA is currently planning for a new optical communications relay node in geostationary (GEO) orbit to be commissioned in 2025, developed by NASA’s Goddard Space Flight Center (GSFC), as evolved from Goddard’s Laser Communications Relay Demonstration (LCRD) GEO relay payload that will launch in 2019. The Next Generation optical relay node will serve as an initial element in a larger optical networking constellation that will consist of Government and commercial, and international relays. NASA’s nodes will aggregate traffic at data rates of up to 10 Gigabits per second (Gbps) from users on the Earth’s surface and up through suborbital, LEO, MEO, GEO, cislunar and even out to Earth-Sun Lagrange (1.25 Mkm) distances. Users that require low-latency will be serviced with an onboard complementary Ka-band downlink service. The next generation network will deploy > 100 Gbps space-to-ground links and also optical crosslinks between nodes to allow for user traffic backhaul to minimize ground station location constraints.
      • 04.0402 MSL Relay Coordination and Tactical Planning in the Era of InSight, MAVEN, and TGO Pegah Pashai (Jet Propulsion Laboratory), Rachael Collins (NASA Jet Propulsion Lab) Presentation: Pegah Pashai - Monday, March 4th, 09:25 PM - Amphitheatre
        This study examines an approach for optimizing the scheduling of regular relay communications between the Mars Science Laboratory (MSL) rover and the non-sun-synchronous Mars orbiters MAVEN and TGO as well as the impacts of the approaching InSight landing on MSL relay and tactical planning. With the introduction of InSight, MAVEN, and TGO, the MSL mission undertook a design effort in order to define new overflight selection criteria and identify the impact to operational efficiency. Instead of selecting all usable relay opportunities, as was the case with just MRO and ODY, this new paradigm requires deconflicting and down-selecting from available overflights. The overflight selection algorithm presented in this study selects based on key overflight metrics such as timing, the predicted data volume return, and the latency between the relay and data arrival to Earth. The relative priority of each of these metrics are scenario specific; thus, the algorithm is flexible and configurable for when mission priorities evolve. Additionally, operational constraints and considerations such as human factors are applied. The resulting tactical planning timeline post-InSight landing suggests comparable operational efficiency to the pre-InSight era but yields more variation in the timing of the planning shifts, adding strain on the MSL planning team.
      • 04.0403 Proximity Link Telecommunication and Tracking Scenarios for a Potential Mars Sample Return Campaign Charles Edwards (Jet Propulsion Laboratory), Allen Farrington (Jet Propulsion Laboratory), Roy Gladden (Jet Propulsion Laboratory), Charles Lee (Jet Propulsion Laboratory), Robert Lock (Jet Propulsion Laboratory), Austin Nicholas (NASA Jet Propulsion Lab), Ryan Woolley (Jet Propulsion Laboratory), Brian Muirhead (Jet Propulsion Laboratory), Orson Sutherland (European Space Agency) Presentation: Charles Edwards - Monday, March 4th, 09:50 PM - Amphitheatre
        A Mars Sample Return (MSR) campaign would involve a series of three flight missions to acquire and cache Mars samples, retrieve those samples and launch them into Mars orbit, and then capture these samples and return them to Earth. Relay communications would be crucial for supporting this campaign, characterized by multiple critical events, complex surface operations, and an on-orbit Mars rendezvous. The existing Mars relay network offers significant capability, and efforts are underway to maximize the likelihood that one or more of these current assets will still be operational in the timeframe of an MSR campaign. In addition, the Earth Return Orbiter (ERO) element of a campaign could serve as a primary relay asset, if it can achieve a useful relay orbit by the time of arrival of the Sample Retrieval Lander mission. We describe key operational challenges of the MSR campaign that would drive the required relay capabilities, and characterize the performance of the existing relay orbiters as well as ERO itself in meeting those relay needs.
    • 04.05 Space Communication Systems Roundtable : Networking the Solar System Charles Edwards (Jet Propulsion Laboratory)
      • 04.05 4.05 Space Communication Systems Roundtable : Networking the Solar System Charles Edwards Presentation: Charles Edwards - - Dunraven
        The roundtable will provide a forward-looking view of the development of a Solar System Internetwork - a layered architecture aimed at offering ubiquitous, high-bandwidth communication throughout the solar system in support of robotic and, ultimately, human exploration in deep space. Panelists will assess trends in physical layer capabilities, including migration to higher RF frequencies (Ka-band) and/or to optical wavelengths, as well as higher layers in the protocol stack, including networking protocols such as DTN, suited for use in long light-time applications. Based on assessment of forecasted commercial satcom trends, and building on the multi-hop relay capabilities operating today at Earth and at Mars, the roundtable will describe the evolution towards a true Solar System Internetwork in the coming decades.
    • 04.06 Innovative Space Communications and Tracking Techniques Kar Ming Cheung (Jet Propulsion Laboratory) & Alessandra Babuscia (NASA Jet Propulsion Laboratory)
      • 04.0602 Teleommand/Telemetry Ranging for Deep-Space Applications Victor Vilnrotter (Jet Propulsion Laboratory), Jon Hamkins (Jet Propulsion Laboratory) Presentation: Victor Vilnrotter - -
        There is current interest in developing a ranging concept for deep-space applications, that does not rely on regenerated sequential sinusoids or pseudonoise (PN) codes on both the uplink and downlink legs of the communications link. These conventional ranging signals require a separate ranging channel, which expand the required bandwidth and consume some of the available spacecraft power on the downlink. Previous papers on Telemetry Based Ranging have examined a new concept that transmits a PN code on the uplink within the signal-band, hence does not expand the bandwidth. This approach makes use of the known structure of the PN code to measure the uplink phase, which is relayed to the ground station enabling measurement of the two-way delay, and hence the total range. Here we expand further on this new concept by replacing the uplink PN code with operational command sequences consisting of encoded and randomized information bits not known a priori to the spacecraft, thus requiring new techniques to determine the uplink delay to the desired accuracy. We examine several extensions of the previously studied PN code concept, including the use of demod-remod techniques on the received codewords at the spacecraft, to aid in the determination of the uplink delay that must be relayed to the ground to complete the range measurement. Performance in terms of range resolution will be determined, and compared with previous techniques to evaluate the degree of improvement afforded by this new approach.
      • 04.0603 X-BAND PN DOR Signal Design and Implementation on the JPL Iris TRANSPONDER Mazen Shihabi (Jet Propulsion Laboratory) Presentation: Zaid Towfic - Tuesday, March 5th, 08:30 AM - Amphitheatre
        This paper describes the design and implementation of the Pseudorandom-Noise (PN) Delta Differential One-way Ranging (DDOR) signal format on the JPL Iris Cubesat Software Defined Radio. The spread spectrum Delta DOR format enables more accurate differential ranging measurements over the classical DOR tone format, and it is applicable to deep space missions that require accurate navigation or require accurate angular position measurements for another purpose such as determining the ephemeris of a planet or small body.
      • 04.0604 Omnidirectional Optical Communicator Jose Velazco (Jet Propulsion Laboratory) Presentation: Jose Velazco - Tuesday, March 5th, 08:55 AM - Amphitheatre
        We are developing an inter-satellite omnidirectional optical communicator (ISOC) that will enable cross-link communications between spacecraft at Gbps data rates over distances of up to thousands of kilometers in free space. The ISOC under development features a truncated dodecahedron geometry that can hold and array of fast photodiode detector detectors and gimbal-less MEMS scanning mirrors. The main goals of the ISOC development include: 1) full sky coverage, 2) Gbps data rates and 3) the ability to maintain multiple simultaneous links. We have developed two omnidirectional communicator prototypes capable of full-duplex operation. We are using advanced, efficient lightweight single-mode laser diodes operating at 850 nm capable of producing hundreds of milliwatts of laser radiation. We are also employing MEMS-based beam steering mirrors, and fast PIN photodiodes to achieve long range communications. The ultimate goal of the project is to achieve full duplex operation at 1 Gbps data rates over 200 km and slightly lower data rates at longer distances. This paper will describe the overall ISOC architecture and will present the design tradeoffs for gigabit data-rate operation. We will also present preliminary NRZ On-Off Keying communications results obtained using our ISOC prototypes. The ISOC is ideally suited for crosslink communications among small spacecraft, especially for those forming a swarm and/or a constellation. Small spacecraft furnished with ISOC communications systems, should be able to communicate at gigabit per second rates over long distances. This data rate enhancement can allow real-time, global science measurements and/or ultra-high fidelity observations from tens or hundreds of Earth-orbiting satellites, or permit high-bandwidth, direct-to-earth communications for planetary missions.
      • 04.0607 POINTR: Polar Orbiting INfrared Tracking Receiver Michael Taylor (Stanford University), Anjali Roychowdhury (Stanford University), Sasha Maldonado (Stanford University), Orien Zeng (Stanford University), Shi Tuck (Stanford SSI), Michal Adamkiewicz (Stanford University), Sandip Roy (Stanford University), Jake Hillard (Stanford University), Simone D'amico (Stanford University) Presentation: Michael Taylor - Tuesday, March 5th, 09:20 AM - Amphitheatre
        The Satellites Team of the Stanford Student Space Initiative (SSI) has designed and built the Polar-Orbiting Infrared Tracking Receiver (POINTR), a 1U cubesat payload to demonstrate fine optical Pointing Acquisition and Tracking (PAT) based on a silicon MEMS fast steering mirror (FSM). POINTR was an entirely student run project to demonstrate optical communications technology at the cubesat scale. POINTR launched Dec 3rd 2018 on Spaceflight SSO-A: SmallSat Express as a hosted payload onboard a 3U cubesat Audacy0. The mission concept and system design of POINTR will be presented along with the prototype construction and ground based testing.
      • 04.0609 Optimizing Multiple Frequency-Shift Keying during Spacecraft Critical Events for Future Missions Shweta Dutta (JPL (Caltech)), Melissa Soriano (Jet Propulsion Laboratory) Presentation: Shweta Dutta - Tuesday, March 5th, 09:45 AM - Amphitheatre
        When attempting to land on a planetary body, perform a complex direction change, or even while simply cruising, challenges arise in spacecraft to Earth communications. If a spacecraft must perform a complicated maneuver such as orbit insertion, the spacecraft often cannot use its High Gain Antenna (HGA) for communication to another craft, or back to Earth. Additionally, if the spacecraft enters a fault state, it is possible that the antennas cannot be oriented as precisely. In these scenarios, a Low Gain Antenna (LGA) may be used to communicate limited information to know that the spacecraft is alive in the former situation, and to recover the spacecraft in the latter situation, so it is imperative to use communication methods that have a high probability of correctly obtaining a weak signal. This study will first summarize the mechanism to predict the probability of successfully detecting the carrier frequency and data tones used in Multiple Frequency-Shift Keying (MFSK, or tones) by the spacecraft, and then explore the applicability of MFSK in future missions for events including but not limited to orbit insertion; entry, decent, and landing (EDL); and safe modes. Using the search space, non-coherent integration time, fast Fourier Transform (FFT) bandwidth, and modulation index, one may compute the predicted probability of correctly detecting and tracking a frequency versus the total power to noise ratio. Tones allowed for communication with planetary landers and other spacecraft in the past, namely the Mars Exploration Rover (MER), Mars Science Laboratory (MSL), both primarily for EDL, and Juno for orbit insertion. Following the models outlined in [1], we demonstrate the probability of properly detecting a tone during JOI to be greater than 99% under worst-case expected operating conditions for the Europa Clipper mission. We also examine the optimal use of tones during other spacecraft critical events, such Europa Clipper’s safe mode recovery via examination of parameter modifications to MFSK as used in Juno, MER, and MSL, and comparing how these modifications perform compared to the original technique.
      • 04.0610 Single-Satellite Doppler Localization with Law of Cosines (LOC) Kar Ming Cheung (Jet Propulsion Laboratory), William Jun (Georgia Institute of Technology), Edgar Lightsey (Georgia Institute of Technology), Charles Lee (Jet Propulsion Laboratory) Presentation: William Jun - Tuesday, March 5th, 10:10 AM - Amphitheatre
        Modern day localization requires multiple satellites in orbits, and relies on ranging capabilities which may not be available in most proximity flight radios that are used to explore other planetary bodies such as Mars or Moon. The key results of this paper are: 1. A novel relative positioning scheme that uses Doppler measurements and the principle of the Law of Cosines (LOC) to localize a user with as few as one orbiter. 2. The concept of “pseudo-pseudorange” that embeds the satellite’s velocity vector error into the pseudorange expressions of the user and the reference station, thereby allowing the LOC scheme to cancel out or to greatly attenuate the velocity error in the localization calculations. In this analysis, the Lunar Relay Satellite (LRS) was used as the orbiter, with the reference station and the user located near the Lunar South Pole. Multiple Doppler measurements by the stationary user and the reference station at different time points from one satellite can be made over the satellite’s pass, with the measurements in each time point processed and denoted as from a separate, faux satellite. The use of the surface constraint assumption was implemented with this scheme; using the knowledge of the altitude of the user as a constraint. Satellite’s ephemeris and velocity, and user’s and reference station’s Doppler measurement errors were modeled as Gaussian variables, and embedded in Monte Carlo simulations of the scheme to investigate its sensitivity with respective to different kinds of errors. With only two Doppler measurements, LOC exhibited root mean square (RMS) 3D positional errors of about 22 meters in Monte Carlo simulations. With an optimal measurement window size and a larger number of measurements, the RMS error improved to under 10 meters. The algorithm was also found to be fairly resilient to satellite velocity error due to the error mitigating effects in the LOC processing of the pseudo-pseudorange data type. A sensitivity analysis was performed to understand the effects of errors in the surface constraint, showing that overall position error increased linearly with surface constraint error. An analysis was also performed to reveal the relationship between the distance between the user and the reference station; a distance of up to 100 km only lead to an increase of 10 meters in RMS 3D position error. Ultimately, the LOC scheme provides localization with a minimal navigation infrastructure that relaxes hardware requirements and uses a small number of navigation nodes (as small as one).
    • 04.07 Space Navigation Techniques Amir Emadzadeh (Nvidia) & Lin Yi (NASA Jet Propulsion Lab)
      • 04.0701 Autonomous Orbital Rendezvous Using a Coordinate-Free, Nonsingular Orbit Representation Matthew Walsh (Cornell University) Presentation: Matthew Walsh - Wednesday, March 6th, 09:00 PM - Amphitheatre
        Orbital rendezvous is a fundamental operation for spacecraft navigation and essential for accomplishing many mission goals. Here, we develop a general method to execute orbital rendezvous, verify it in simulations in a Keplerian gravity model, and analyze the effects of perturbations. The method uses a coordinate-free representation of the orbit by representing the state as angular momentum, orbital energy, and vector eccentricity as a basis for discrete feedback control. These quantities offer several qualities that make them attractive for use in closed-loop control. They do not depend on coordinate representation, are nonsingular, and are stationary in the dynamic steady-state of no applied forces. Further, their dynamics are governed by simple equations, leading to a simple transition matrix. Rendezvous is accomplished in two phases where the spacecraft state is split into a 5 degree-of-freedom orbit, which is matched first in an orbit matching maneuver, and an along-track position, which is matched in a phasing maneuver. Once within a short distance of the target position, the spacecraft can enter a close-proximity mode that utilizes a previously developed state transition matrix of relative motion (such as Clohessy-Wiltshire or Tschauner-Hempel) for higher precision. Simulation results permit a comparison of Delta V to that of other techniques. The primary benefits of this method are that it can be used for arbitrary orbits, executes autonomously, and avoids limitations by either singularities or linearized dynamics. This efficient, autonomous method for executing orbital rendezvous improves the feasibility and robustness of small spacecraft missions because it does not require a dedicated ground station or constant communication during maneuver execution.
      • 04.0702 A Static Estimation Method for Autonomous Navigation of Relativistic Spacecraft Doga Yucalan (Cornell University), Mason Peck (Cornell University) Presentation: Doga Yucalan - Wednesday, March 6th, 09:25 PM - Amphitheatre
        In-situ space exploration beyond our solar system is an inevitable next step for science. Such spacecraft will travel much faster, with speeds that are a significant fraction of the speed of light, to realize extrasolar exploration in a human lifetime. However, existing navigation technologies are not up to the task because they are generally Earth-based, exploiting the Deep Space Network for tracking. They lack the resolution to estimate the state of a high-speed spacecraft in the interstellar medium, and the long light-travel times likely preclude sharing state information with the spacecraft for active trajectory control. Moreover, all rely on reference-frame-independent physical laws and treat relativistic effects as perturbations of classical theories of orbital mechanics. Given the unprecedented uncertainty that interstellar environment can introduce in the trajectory of such a spacecraft, on-board navigation is likely the only feasible approach. This paper describes autonomous navigation for spacecraft traveling at relativistic speeds. The special theory of relativity is central to its flight-dynamics model. The proposed method assumes that the spacecraft has access to a state-of-the-art star catalog describing the relative positions and colors of a number of stars and can detect relative directions and apparent colors of the corresponding stars onboard with a star tracker and a spectrometer. By relating the motion of the spacecraft to these observations in the spacecraft’s reference frame, the algorithm estimates its instantaneous position and velocity. The paper includes the results of simulations of the linearized equations for a spacecraft having a generic star tracker and a spectrometer as a sensor, traveling from Earth to Proxima Centauri at 20 percent of the speed of light. Results show that the algorithm can estimate the position and velocity of the spacecraft with less than 0.5 percent error. Assuming the key relativistic effects are apparent in the sensors, this approach provides a universal navigation algorithm that can be used by any space vehicle traveling at arbitrarily high speed. This work represents an enabling step toward relativistic spaceflight.
      • 04.0703 Point-to-CAD 3D Registration Algorithm for Relative Navigation Using Depth-Based Maps Antonio Teran Espinoza (Massachusetts Institute of Technology), Timothy Setterfield (Jet Propulsion Laboratory, California Institute of Technology) Presentation: Antonio Teran Espinoza - Wednesday, March 6th, 09:50 PM - Amphitheatre
        This paper presents an end-to-end 3D registration algorithm for relative navigation between known objects based on a point-to-CAD iterative closest point (ICP) principle. The objective of this method is to take in a measured point cloud extracted from a depth or disparity map – such as the ones obtained from stereo cameras, time-of-flight cameras, LiDARs, or depth from defocus sensors – and calculate the rigid body transformation that best aligns the measured data with a corresponding 3D CAD model. By leveraging the geometric information encoded into stereolithography (STL) files, it is sought to address the computational intractability imposed by the naı̈ve generation of dense target point clouds solely based on the target’s known surface. To this end, the proposed approach computes a bijective projection onto the known triangular mesh to obtain a target point cloud with which to use ICP techniques for incremental alignment; the projection step is then carried on recursively until the convergence criteria are met, yielding a relative 6DOF pose between the two objects to be used within the estimation pipeline. Demonstrations of the algorithm are presented using simulated datasets; results include time complexity analyses for real-time operation cases and performance variation assessments with respect to CAD model complexity. The design and implementation of the algorithm makes use of the open-source Point Cloud Library, and access to its source code is included within this work.
    • 04.08 Communication System Analysis & Simulation Yogi Krikorian (Aerospace Corporation)
      • 04.0801 Performance and Utilization Results for Time-Triggered Data Transfers over SpaceWire Kai Borchers (German Aerospace Center - DLR), Daniel Lüdtke (German Aerospace Center - DLR), Sergio Montenegro (University Würzburg), Frank Dannemann (German Aerospace Center - DLR) Presentation: Kai Borchers - Wednesday, March 6th, 10:35 AM - Lake/Canyon
        SpaceWire as a serial communication technology is widely used throughout the space domain but is still insufficient in providing real-time data transfers, especially if network structures contain cascaded routers. This paper presents a system capable to overcome this limitation by use of a timetriggered data transfer with focus on a decentralized time distribution. Besides the introduction of technical concepts, startup behavior and clock synchronization is evaluated for a whole network. This evaluation is done with respect to different network configurations and injection of oscillator uncertainties. The system is implemented by a hardware description language to be used on a Field Programmable Gate Array (FPGA). Therefore the FPGA resource utilization and the maximum operation frequency are investigated for different target devices.
      • 04.0802 Statistical Optical Link Budget Analysis Hua Xie (Jet Propulsion Laboratory), Kar Ming Cheung (Jet Propulsion Laboratory) Presentation: Kar Ming Cheung - Wednesday, March 6th, 11:00 AM - Lake/Canyon
        In this paper, we describe work on extending statistical analysis methods to optical communications links, with a primary focus on intensity modulated, direct detected photon-counting channel utilizing pulse-position-modulation (PPM). We performed analysis on the relationship between bit error rate (BER) requirement, statistical characteristics of the received signal power and noise power, and the coded performance curves. We presented link analysis results with preliminary uncertainty quantifications of signal power and noise power. We used the Consultative Committee for Space Data Systems (CCSDS) Serially Concatenated convolutionally coded Pulse Position Modulation (SCPPM) prototype software to obtain coded performance curves under different operating conditions with varying signal power, background noise power, code rates, and PPM modulation orders. Comparison with traditional, deterministic analysis shows that extra margin needs to be reserved to compensate for the performance losses caused by uncertainties of the link parameters.
      • 04.0804 Dynamic Link Analysis and Application for a MEO Space Vehicle Gleason Chen (The Aerospace Corporation), Jack Kreng (Aerospace Corporation), Yogi Krikorian (Aerospace Corporation) Presentation: Gleason Chen - Wednesday, March 6th, 11:25 AM - Lake/Canyon
        The study is to perform dynamic link analysis to determine the earliest separation time of the Space Vehicle (SV) from the Launch Vehicle (LV) while meeting the SV link requirements for Telemetry, Tracking and Control (TT&C) uplink & downlink services from/to ground stations. Successful rocket launch required adequate link coverage throughout the flight and good Radio Frequency (RF) performance. The presentation will discuss the concept of the dynamic link analysis, SV antenna switching schedule, recommended SV separation time, as well as the performance for different launch scenarios within the 24-hour launch window. Topics will include antenna patterns, launch trajectories, elevation angle, and clock & cone angle geometry, and dynamic link budgets. The 3 dynamic link analyses, covering from lift-off at TEL to orbital insertion over DGS station, using 3 different waveforms are given to cover the 3 segments of the LV trajectory (Range Digital FM from Tel-4 and ANT to LV, NASA QPSK from LV to TDRSS, and SGLS from DGS to space vehicle).
    • 04.09 Wideband Communications Systems David Taggart (Self) & Claudio Sacchi (University of Trento)
      • 04.0901 A Genetic Algorithm for Joint Power and Bandwidth Allocation in Multibeam Satellite Systems Aleix Paris (Massachusetts Institute of Technology), Inigo Del Portillo (Massachusetts Institute of Technology), Bruce Cameron (Massachusetts Institute of Technology), Edward Crawley (Massachusetts Institute of Technology) Presentation: Aleix Paris - Wednesday, March 6th, 04:30 PM - Lamar/Gibbon
        Dynamic resource management (DRM) techniques for communications satellites are essential to make better use of on-board resources and the available spectrum, and to satisfy the varying demands within the satellite broadband market. This paper presents a new method for joint power and bandwidth allocation in multibeam satellite systems. To that end, we first develop a multibeam satellite model that accounts for propagation effects, interference among beams, and atmospheric attenuation. Next, we formulate the joint power and bandwidth allocation optimization problem and propose a novel algorithm to solve it. The basis of this algorithm is a genetic algorithm that is combined with repair functions to guarantee the validity of the solutions and speed up convergence. We conclude our presentation showing the usefulness of the algorithm by analyzing two case studies: a notional case featuring a 37-beam satellite and a realistic case based on Viasat-1. The results obtained show that our joint power and bandwidth allocation algorithm can reduce the unmet system capacity (USC) by up to 40% (compared to just power allocation approaches). Furthermore, our experiments identify the variation of the demand among beams as a parameter that has a large impact on potential improvement: the higher the variation in demand among beams, the more beneficial it is to allow a greater flexibility in the range of bandwidth allocations allowed.
      • 04.0902 A Virtualized Border Control System Based on UAVs: Design and Energy Efficiency Considerations Claudio Sacchi (University of Trento) Presentation: Claudio Sacchi - Wednesday, March 6th, 04:55 PM - Lamar/Gibbon
        European borders are hard to be controlled in an effective and efficient way. The recent emergencies related to immigration revealed the substantial inefficiency of conventional means of border patrolling based on warships, coast guard speedboats and helicopters. A reliable technical answer to these emergency problems may come from the use of different kinds of unmanned aerial vehicles (UAVs). These flying vehicles may allow at improving border control. Nevertheless, such technologies require significant amount of personnel, energy and infrastructure to properly serve border protection. In order to be really effective, UAVs should autonomously cooperate in networked manner, collecting information from the on-ground and/or water-surface sensors, exchanging data among them and conveying the critical information to remote border control centres. This is the main objective of DAVOSS project (Dynamic Architectures based on UAVs Monitoring for border Security and Safety), funded by NATO in the framework of the Science for Peace and Security Programme. This paper aims at presenting the novel adaptive and virtualized aerospace network architecture proposed in DAVOSS. The leading concepts of DAVOSS are flexibility, dynamic reconfigurability, energy efficiency and broadband connection availability also in critical application scenarios. In order to improve robustness and resilience of the avionic network and to enable the efficient information backhaul also in absence of terrestrial links, advanced networking and communications technologies like Software-Defined Networking (SDN), network slicing and virtualization are introduced. System requirements, coming from potential end-users, along with real application scenarios will be carefully analyzed in order to drive the architectural design phase, whose preliminary outcomes will be shown in the paper. Preliminary results demonstrate the effectiveness of the adoption of virtualization techniques for the considered aerospace network architecture in terms of reduced power consumption at the drone side, with an observed tradeoff with latency.
      • 04.0903 Measurement Sensitivity of Modulation Indices in Telemetry, Tracking, and Command Systems Srinivasa Raghavan (Aerospace Corporation) Presentation: Srinivasa Raghavan - Wednesday, March 6th, 05:20 PM - Lamar/Gibbon
        The Space Ground Link Subsystem (SGLS) is an example of the TT&C system using a subcarrier and direct modulation together in a phase modulator. In this system, telemetry signal is placed on a 1.7 MHz subcarrier and ranging and command signals are placed directly on the carrier. The ranging signal is made up of a 1 mega-chip-per-second pseudorandom code, modulating the carrier signal using binary phase shift keyed modulation (BPSK). The command signal is made up of 3-tone frequency shift keyed signal amplitude modulation (AM). All the three signals together phase-modulate (PM) the carrier before transmission. The performance of each of the services is dependent on the amount of power in those services. It is important to measure the modulation indices accurately to assure the power distribution required for the service performance. In this paper the issues related to the measurement of command and telemetry modulation indices are addressed and the link sensitivity to the measurement errors in modulation indices is also discussed.
      • 04.0904 Satellite SDR Gateway for M2M and IoT Applications Vlad Popescu (Transilvania University of Brasov), Cristinel Gavrila (Transilvania University of Brașov ), Marian Alexandru (Transilvania University of Brasov), Claudio Sacchi (University of Trento), Daniele Giusto (University of Cagliari) Presentation: Vlad Popescu - Wednesday, March 6th, 09:00 PM - Lamar/Gibbon
        Short-range terrestrial radio communications, in low-power and low-cost configurations are the current enabler for the IoT and M2M applications. The main drawback of such applications is the need of a gateway that enables them to communicate with the world. Satellite gateways have become in recent years more affordable, opening the possibility to the aforementioned applications to get even more present in the current technological development, but still the combined equipment and especially the access costs are still prohibitive for large scale deployments. The equipment costs for a satellite gateway could be substantially lowered using the Software Defined Radio (SDR) concept which can provide a high degree of flexibility in dynamically operating multiple wireless interfaces, especially combined with the plethora of terrestrial communication standards. The design of an embedded hardware device based on SDR technologies would therefore significantly lower the overall costs of satellite communication for IoT and M2M applications. Combining the presented elements, the main goal of this paper is to analyze the requirements of the satellite part of a SDR-based gateway for M2M and IoT applications and to present a hardware implementation of the gateway together with its operational characteristics.
      • 04.0905 Performance and Hardware Complexity Trade-offs for Digital Transparent Processors in 5G Satcoms Vincenzo Sulli (University of L'Aquila ), Giuseppe Marini (University of L'Aquila), Fortunato Santucci (University of L'Aquila), Marco Faccio (University of L'Aquila), Graziano Battisti (Università degli Studi dell'Aquila) Presentation: Giuseppe Marini - Wednesday, March 6th, 09:25 PM - Lamar/Gibbon
        With the fifth generation (5G) wireless technology paradigm, huge efforts have been made in the very latest years to incorporate satellite communications. Indeed, in this global frame satellite communications can provide a valuable resource to extend and complement terrestrial networks both in terms of throughput and global connectivity. When on-board transponders are considered, transparent satellites may be considered as an appealing solution to provide backhaul connectivity to the on-ground Relay Nodes. Nevertheless, along the last decade semi-transparent transponder architectures have received major attention. This kind of architectures have been emerging as a viable alternative to provide broadband connectivity in modern network topologies with large users' populations and a variety of requirements in terms of bandwidths and QoS, while maintaining the payload complexity affordable. In this frame, significant on-board digital processing is involved, which calls for careful system modeling and accurate digital hardware design to achieve feasible trade-offs between hardware efficiency and overall link-budget performance. In these regard, an equivalent noise model for the analog-digital hybrid receiving chain that composes the satellite transparent transponder has been proposed in our recent works. The proposed analytical method is applied to a specific DTP (Digital Transparent Processor) architecture and the validation is discussed by comparing results with those obtained via Monte Carlo simulation. A detailed description of the architecture of each block within the DTP chain has been provided, by also enclosing the hardware complexity analysis of the basic building blocks and of the whole DTP chain. Numerical examples, that illustrate the application of the developed framework and the related design methodology in scenarios of practical interest, have been presented, with a first HW validation of the design choices in the DTP chain. In the present paper the theoretical framework is extended in order to take into account the actual hardware resource utilization and the related power consumption for a given Field Programmable Gate Array (FPGA) technology.
      • 04.0907 UWB Air-to-Ground Propagation Channel Measurements and Modeling Using UAVs Wahab Ali Gulzar Khawaja (North Carolina State University), Ozgur Ozdemir (NCSU), Fatih Erden (North Carolina State University), Ismail Guvenc (), David Matolak (University of South Carolina) Presentation: Wahab Ali Gulzar Khawaja - Wednesday, March 6th, 09:50 PM - Lamar/Gibbon
        This work is conducted to analyze the air-to-ground propagation channel for ultra-wideband radio signals. The ultra-wideband air-to-ground communication is carried out using a low flying unmanned aerial vehicle. Different propagation scenarios are used in the open field. In addition, different antenna orientations are used for the dipole antennas on the unmanned aerial vehicle. The channel measurements are used to obtain the path loss and number of multipath components. The empirical channel impulse response is modeled using the Saleh Valenzuela model.
    • 04.10 Communications and/or Related Systems: Theory, Simulation, and Signal Processing Rajendra Kumar (California State University) & David Taggart (Self)
      • 04.1001 Channel Estimation for a Multi-User System with Iterative Interference Cancelation Lukas Grinewitschus (Universität Duisburg-Essen), Christian Schlegel (Dalhouse University) Presentation: Lukas Grinewitschus - Monday, March 4th, 09:20 AM - Amphitheatre
        To allow multiple-access between small earth terminals and a satellite hub in a fully unsynchronized manner, the authors present a hub receiver which uses iterative interference cancelation on the physical-layer to separate the traffic. Instead of approaches like Contention Resolution Diversity Slotted ALOHA, which operates on the data-link layer, the receiver presented allows for interference cancelation within one time slot. While the general structure of the hub receiver was already introduced, the estimation and equalization of channel impairments like sampling-clock offsets as well as carrier frequency offsets are targeted here. The system model is introduced briefly and channel estimation and equalization approaches are presented. For channel estimation the authors recommend a correlation-based channel tap estimator which uses the preamble as well as received and corrected data as pilots for better channel estimation in subsequent iterations. To equalize channel impairments two kinds of single-tap equalizers are investigated. The impact of the estimation and equalization approaches on the bit error rate performance of the system in comparison to previous investigated scenarios where the channel was assumed known are studied.
      • 04.1002 Acquisition and Tracking for Communications between Lunar South Pole and Earth Dariush Divsalar (Jet Propulsion Laboratory), Marc Sanchez Net (Jet Propulsion Laboratory), Kar Ming Cheung (Jet Propulsion Laboratory) Presentation: Marc Sanchez Net - Monday, March 4th, 09:45 AM - Amphitheatre
        In this paper we design and analyze an end-to-end communication system between a lander/rover on the surface of the lunar South Pole and an Earth station. The acquisition and tracking system is discussed in detail. The communication system on the lander or rover could be used for the Earth-to-Moon communication. To communicate to and from the lander/rover on the lunar South Pole, low and/or medium directional antennas onboard the lander/rover will have to be pointed at low elevation angles between 2 to 10 degrees, thus causing multipath fading effects due to reflection of a portion of the transmitted electromagnetic waves from the surface of the Moon that are not commonly encountered in traditional deep space communications between a spacecraft and a ground station. To design and analyze such a communication system, and in particular the acquisition and tracking system, in the presence of multipath fading, first we model the fading channel based on existing and simulated data. In addition to multipath fading, the channel also introduces Doppler frequency up to 11.5 KHz, and Doppler rate up to 0.735 Hz/sec. For coherent reception the Doppler frequency, which is time varying, should be acquired and the incoming carrier phase, which includes the fading phase, should be tracked in the presence of multipath fading. For this communication system in addition to estimating the received carrier phase, the amplitude of the fading signal should also be estimated, in particular to be used in the decoder. In addition to acquisition and tracking, we consider simple modulation and coding schemes. Space diversity using two antennas on earth to mitigate the effects of fading could also be used. We design phase-locked loops and frequency sweeping schemes robust to the attenuations due to fading. After designing various components of the communication system, we use Simulink models to obtain the end-to-end performance of the communication link under investigation. Based on the available data, the fading channel can be accurately modeled as a Rician fading channel with Rician parameter of 10 dB, and Doppler spread that depends on the Doppler frequency and the transmit/receive antenna patterns. The challenge is how to make such a communication system robust in the presence of the multipath fading where the Doppler spread changes in time and thus produces fading with time-varying durations (short and very long fades). In summary, this paper covers communication system design, performance analysis, and simulations for performance of Doppler frequency acquisition, tracking, uncoded system, and coded system under ideal interleaving assumption with hard decision over communication link between a lander/rover at the Lunar south pole and a DSN Earth station in presence of Rician fading.
      • 04.1003 Resilient Synchronization of Radio Networks of Clocks: A Pursuit-Evasion Graphical Game Approach Khanh Pham (Air Force Research Laboratory) Presentation: Khanh Pham - Monday, March 4th, 10:10 AM - Amphitheatre
        This paper provides an analytical framework to in- vestigate judicious topology reweighting of radio networks of clocks, when distributed time transfer and synchronization are based on physical layers and subject to the presence of false timing signals. Protagonist clocks exchange timing information pairwise, which is modeled as clocks tending to follow the ma- jority of their neighbors. Antagonist clocks inject false timing signals, thereby, influencing the timing synchronization of (some of) the other protagonist clocks they meet. A class of pursuit- evasion graphical games subject to complete state observations and exploitation of phase noise disturbances, is proposed in designing clock steering protocols for resilient time metrologies that will be immune to erroneous timing signals injected into remote time dissemination networks.
      • 04.1004 Using Control Engineering to Improve Regulatory Review of Flexible SATCOM Terminal Advocacy Khanh Pham (Air Force Research Laboratory) Presentation: Khanh Pham - Monday, March 4th, 10:35 AM - Amphitheatre
        In this paper, the emphasis is on the feasibility of using learning and control engineering to help SATCOM regulatory agencies more efficiently, consistently, and effectively analyze requests to autonomously operate flow control and dynamic resource allocation consistent with increasing demands for connectivity and bandwidth. Due to the repetitive nature of user experiences, application performances, and service level agreements, terminal assignments of center frequencies for transmission, signal bandwidths, communication modes, and time intervals for transmission could benefit from the data collected during previous downlink mode change requests and uplink terminal reports. Intelligent terminal agents and enforcement coordination between terminal routers and modems are proposed and discussed in the views of iterative learning and Minimal-Cost-Variance (MCV) control-theoretic frameworks.
      • 04.1006 Joint Sensing and Communications Multiple-Access System Design and Experimental Characterization Richard Gutierrez (The Aerospace Corporation), Daniel Bliss (Arizona State University) Presentation: Richard Gutierrez - Monday, March 4th, 11:00 AM - Amphitheatre
        One solution to addressing the spectral congestion problem is to co-design communications and remote sensing systems to cooperate, such that each system benefits from the presence of one another. In this work, we present a novel joint sensing and communications multiple access system architecture that allows for simultaneous decoding of communications information and radar target tracking and parameter estimation within the same space, time, and frequency continuum. We further demonstrate the feasibility of this co-design architecture by implementing it on a network of software defined radios (SDRs). To characterize the system we consider a scenario where one transceiver transmits an emulated radar return waveform, while a second transceiver simultaneously transmits a communications waveform. A third transceiver receives and processes the emulated radar return and communications waveforms jointly. The radar transmitter and joint sensing and communications receiver acts as a quasi-monostatic tracking radar. We characterize the joint performance of the system using the communications and estimation rate metrics. The results show that the system decodes communications information with less than 2\% bit errors and achieves excellent radar tracking performance for the given experiment parameters. This work demonstrates the feasibility of such a system using low cost commercial-off-the-shelf (COTS) transceiver hardware and demonstrates previously reported analytical results on system performance.
      • 04.1007 Designing and Implementing SVMs for High-Dimensional Knowledge Discovery Using FPGAs John Porcello (N/A) Presentation: John Porcello - Monday, March 4th, 11:25 AM - Amphitheatre
        Support Vector Machines (SVMs) represent a robust and valuable tool for Machine Learning. SVMs are resilient to overfitting and can provide useful information for high-dimensional data when sufficient hyperplane margin can be identified. However, SVMs require substantial computational load for large datasets. This paper discusses SVMs, analyzing SVM results, and classification of high-dimensional data for the purpose of Knowledge Discovery. Furthermore, this paper considers implementation of SVMs using Field Programmable Gate Arrays (FPGAs). The approach described in this paper applies to high performance, high throughput and scalable implementations for big data. The paper provides design data for FPGA implementation of SVMs. Finally, an example is provided is based on the Xilinx UltraScale+ FPGAs to illustrate the concepts in this paper.
    • 04.11 Global Navigation Satellite Systems Gabriele Giorgi (German Aerospace Center - DLR) & Lin Yi (NASA Jet Propulsion Lab)
      • 04.1103 A Future GNSS Constellation with Inter-satellite Links: Preliminary Space Segment Analyses Gabriele Giorgi (German Aerospace Center - DLR), Bethany Kroese (), Grzegorz Michalak (Helmholtz Centre Potsdam German Research Centre for Geosciences - GFZ) Presentation: Gabriele Giorgi - Wednesday, March 6th, 04:30 PM - Amphitheatre
        A potential development in future Global Navigation Satellite Systems is the use of optical inter-satellite links and optical frequency references to provide enhanced navigation and timing services. These services are chiefly dependent on the tight synchronization of signals broadcast by the constellation’s satellites, which in turn depend on the stability of their frequency references, the capabilities of time and frequency transfer schemes, and the accuracy of system’s orbit determination. This presentation discusses recent efforts to design orbits for a constellation of satellites interconnected via optical links. It reports progresses on a linking rule to schedule communication between the elements of the constellation in support of continuous and reliable synchronization capabilities, as well as work on precise orbit determination.
      • 04.1105 Secure Multi-constellation GNSS Receivers with Clustering-based Solution Separation Algorithm Kewei Zhang (KTH Royal Institute of Technology), Panos Papadimitratos (KTH) Presentation: Kewei Zhang - Wednesday, March 6th, 04:55 PM - Amphitheatre
        Because of the limited satellite visibility, reduced signal reception reliability and constraining spatial geometry, e.g., in urban areas, the development of multi-constellation global navigation satellite systems (GNSS) has gained traction rapidly. GNSS-based applications are expected to handle observations from different navigation systems, e.g., GPS, GLONASS, Bei-Dou and Galileo, in order to improve positioning accuracy and reliability. Furthermore, multi-constellation receivers present an opportunity to better counter spoofing and replaying attacks, leveraging approaches take advantage of the redundant measurements. In particular, cluster-based solution separation algorithm (CSSA) proposes to detect and identify faulty/malicious signals in a single GPS constellation by checking the consistency of receiver positions calculated with different number of satellites. Intuitively, the algorithm targets directly the consequence of spoofing/replaying attacks: the victim receiver position error estimation. It works independently of how the attacks are launched, either through modifying pseudorange measurements or manipulating the navigation messages, without changing the receiver hardware. Multi-constellation GNSS receivers utilize all observations from different navigation systems, there are more than 30 available satellites at each epoch after Galileo and BeiDou systems become fully operational; in other words using abundant redundancy. Therefore, we introduce such a CSSA to a multi-constellation receiver. The work shows that a multiconstellation GNSS receiver equipped with our algorithm works effectively against a strong spoofing/replaying attacker that can manipulate a large number of signals, or even an entire constellation. The results show that CSSA with multi-constellation significantly improves the performance of detecting and identifying the malicious signals; particularly, when the adversary cannot control all the constellations, a multi-constellation receiver can identify the faults even the adversary induces very small errors to pseudorange measurements, comparing with a single constellation receiver. Moreover, when the attacker is powerful to manipulate most of signals of all the constellations, a multi-constellation receiver with CSSA can still detect and identify the faulty signals with high probability when the attacker tries to mislead the victim more than a couple of hundred meters from its true location.
      • 04.1106 Precise Positioning of Robots with Fusion of GNSS, INS, Odometry, LPS and Vision Patrick Henkel (Technische Universität München) Presentation: Patrick Henkel - Wednesday, March 6th, 10:35 AM - Madison
        The autonomous driving of robots is coming and requires precise and reliable positioning information with low-cost sensors for the mass market. In this paper, we propose a tightly coupled sensor fusion of multiple complementary sensors including Global Navigation Satellite System (GNSS) receivers with Real-Time Kinematics (RTK), Inertial Measurement Units (IMUs), wheel odometry, Local Positioning System (LPS) and Visual Positioning. The focus of this paper is on the integration of LPS and vision since the coupling of GNSS-RTK, INS and wheel odometry is already state of the art. We include the positions of the LPS anchors and the bearing vectors and distances from the robot’s camera towards the patch features as state vectors in our Kalman filter, and show the achievable positioning accuracies.
    • 04.12 Software Defined Radio and Cognitive Radio Systems and Technology Genshe Chen (Intelligent Fusion Technology, Inc) & Eugene Grayver (Aerospace Corporation)
      • 04.1201 Inter-satellite Range Estimation Using Discovery & Resolution Modes for Space Traffic Management Zakaria Bouhanna (University of Surrey), Christopher Bridges (Surrey Space Centre) Presentation: Christopher Bridges - Friday, March 8th, 08:30 AM - Lamar/Gibbon
        The increase in satellite launches has led to a jump in the number of satellites orbiting Earth to over 1900 active satellites to date. Most of these satellites rely on the two-line elements (TLEs) to define the satellite tracks. However, the accuracy obtained from TLEs is insufficient for accurate satellite collision predictions which led to the undeniable uncertainty regarding satellite conjunction assessment. This paper extends the research conducted about investigating the implementation of a new inter-satellite ranging instrument by proposing two operational modes namely Discovery and Resolution. Discovery allows long-distance satellite detection and fast range estimation from the received signal strength indicator (RSSI). This ensures a larger observation time-window for the Resolution mode to define precisely the nature of the satellite encounter. The system switches to Resolution when the relative range between the satellites source and observer decreases below 10 km according to the scenario studied. Unlike Discovery, Resolution estimates the range from the round-trip propagation delay using sequential ranging techniques. Results reveal that RSSI range measurements are prone to heavy fluctuations due to the path loss variations. In fact, a standard deviation of 63 km for the ranging errors over 1s measurement time is measured however, these measurements are obtained within 2-μs time intervals. On the other hand, Resolution measures the range in chips by calculating the argument of the maxima of the cross-correlation function (CCF) output between the transmitted and the received sequences. Results using Resolution show that an accuracy of 110-m is obtained from a ranging sequence of 800 kcps during 1 s observation window. This value is drastically improved compared to the results achieved with Discovery but with the cost of an acquisition- and processing-time of 20 ms compared to 2 μs attained with Discovery.
      • 04.1203 A Software Radio Based Satellite Communications Simulator for Small Satellites Using GNU Radio Seth Hitefield (), Zachary Leffke (Virginia Tech) Presentation: Seth Hitefield - Friday, March 8th, 08:55 AM - Lamar/Gibbon
        In this paper, we present the architecture for an open source satellite communication simulator that accurately models communications channels between a ground station and satellite. The simulator is implemented using software defined radio (specifically the GNU Radio framework) which allows for an extremely flexible and customizable system. The simulator provides a low-cost platform for testing satellite communication systems that can be used for multiple different scenarios or use-cases throughout the entire development cycle. Examples include: initial mission planning, satellite and ground systems verification, system research and development, mission training and simulation, and education. It can also be integrated into a larger framework for simulating a mission’s command and control structure and/or an entire network of ground stations. The simulator is designed as a module for the GNU Radio framework which allows the end-user to easily customize the toolkit as needed and integrate it into existing frameworks and systems to fit their specific mission objectives. Several flowgraphs are provided that model the communications channel for a satellite in Low Earth Orbit. A simple user interface allows a user to execute these flowgraphs to simulate the pass for a specific satellite. Given the orbital parameters of a satellite, the simulator can model both the uplink and downlink channels for upcoming passes over a specific ground station. The channel flowgraphs themselves model different properties of the communications channel between a satellite and ground station, such as: Doppler shift, path loss, propagation delay, and hardware impairments. Each of these properties is implemented on a per-sample basis within the flowgraph. Different data fitting techniques are used to simulate the channel effect as realistically as possible.
      • 04.1206 Energy Efficient Routing Algorithm for Wireless MANET Genshe Chen (Intelligent Fusion Technology, Inc), Wenhao Xiong (), Dan Shen (Intelligent Fusion Technology, Inc) Presentation: Genshe Chen - Friday, March 8th, 09:45 AM - Lamar/Gibbon
        Genshe Chen is the chief technology officer of Intelligent Fusion Technologies, Inc, Germantown, MD. His research interests include Satellite Communication, cooperative control and optimization for military operations, Target tracking and multi-sensor fusion, Game theoretic estimation and control, and Human-Cyber-Physical system
      • 04.1207 Scaling the Fast X86 DVB-S2 Decoder to 1 Gbps on One Server Eugene Grayver (Aerospace Corporation) Presentation: Eugene Grayver - Friday, March 8th, 09:20 AM - Lamar/Gibbon
        Software implementation of LDPC decoders has been an active area of development for the last 10 years. Researchers have focused on implementing the computationally expensive algorithm on both GPPs and GPUs. A major leap in performance was reported in the groundbreaking paper by Bertrand le Gal [2]. This paper builds on the work in [2] by considering the scaling of that implementation on modern many-core processors. We look at the performance of LDPC code specified in the DVB-S2 standard. The large block size of the DVB-S2 code makes the memory architecture of the processor just as important as the clock rate and instruction set. We present results for two generations of Intel Xeons, an Intel Phi (KNL), the recently released AMD EPYC. The key finding is that performance scaling is limited by the amount of available cache memory rather than the number of cores. We also find that heavily multi-threaded, but deterministic software architecture benefits from explicit allocation of threads to cores vs. allowing the operating system to manage threading. The maximum throughput of 1 Gbps was achieved on a mid-range AMD server – issuing a new era of all-software receivers for very high rate waveforms. We also present the performance of the algorithm ported to a low-power ARM processor and compare that to a low-end Intel Core.
      • 04.1208 Software Defined Radio Implementation of Carrier and Timing Synchronization for Distributed Arrays Han Yan (University of California, Los Angeles), Samer Hanna (University of California, Los Angeles), Kevin Balke (Google, Inc.), Riten Gupta (UtopiaCompression Corporation), Danijela Cabric (UCLA) Presentation: Han Yan - Friday, March 8th, 10:10 AM - Lamar/Gibbon
        The communication range of wireless networks can be greatly improved by using distributed beamforming from a set of independent radio nodes. One of the key challenges in establishing a beamformed communication link from separate radios is achieving carrier frequency and sample timing synchronization. This paper describes an implementation that addresses both carrier frequency and sample timing synchronization simultaneously using RF signaling between designated master and slave nodes. By using a pilot signal transmitted by the master node, each slave estimates and tracks the frequency and timing offset and digitally compensates for them. A real-time implementation of the proposed system was developed in GNU Radio and tested with Ettus USRP N210 software defined radios. The measurements show that the distributed array can reach residual frequency error less than 5 Hz for 70 percent of the time and a residual timing offset less than 1/16 the sample duration all the time. This performance enables distributed beamforming for range extension applications.
    • 04.13 CNS Systems and Airborne Networks for Manned and Unmanned Aircraft Denise Ponchak (NASA Glenn Research Center) & Chris Wargo (Mosaic ATM, Inc.)
      • 04.1301 Advancing the Standards for Unmanned Air System (UAS) Comms, Navigation and Surveillance (CNS) Fred Templin (The Boeing Company) Presentation: Fred Templin - Sunday, March 3th, 04:30 PM - Amphitheatre
        Under NASA program NNA16BD84C, new architectures were identified and developed for supporting reliable and secure Communications, Navigation and Surveillance (CNS) needs for Unmanned Air Systems (UAS) operating in both controlled and uncontrolled airspace. An analysis of architectures for the two categories of airspace and an implementation technology readiness analysis were performed. These studies produced NASA reports that have been made available in the public domain and have been briefed in previous conferences. We now consider how the products of the study are influencing emerging directions in the aviation standards communities. The International Civil Aviation Organization (ICAO) Communications Panel (CP), Working Group I (WG-I) is currently developing a communications network architecture known as the Aeronautical Telecommunications Network with Internet Protocol Services (ATN/IPS). The target use case for this service is secure and reliable Air Traffic Management (ATM) for manned aircraft operating in controlled airspace. However, the work is more and more also considering the emerging class of airspace users known as Remotely Piloted Aircraft Systems (RPAS), which refers to certain UAS classes. In addition, two Special Committees (SCs) in the Radio Technical Commission for Aeronautics (RTCA) are developing Minimum Aviation System Performance Standards (MASPS) and Minimum Operational Performance Standards (MOPS) for UAS. RTCA SC-223 is investigating an Internet Protocol Suite (IPS) and AeroMACS aviation data link for interoperable (INTEROP) UAS communications. Meanwhile, RTCA SC-228 is working to develop Detect And Avoid (DAA) equipment and a Command and Control (C2) Data Link MOPS establishing L-Band and C-Band solutions. These RTCA Special Committees along with ICAO CP WG/I are therefore overlapping in terms of the Communication, Navigation and Surveillance (CNS) alternatives they are seeking to provide for an integrated manned- and unmanned air traffic management service as well as remote pilot command and control. Finally, the Internet Engineering Task Force (IETF) is studying new communications technologies for routing and mobility solutions for Intelligent Transportation Systems (ITS). The technologies developed under the NASA contract are now beginning to emerge as candidates for the IETF standardization efforts in ITS and other domains. This paper presents UAS CNS architecture concepts developed under the NASA program that apply to the aforementioned committees. It discusses the similarities and differences in the problem spaces under consideration in each committee, and considers the application of a common set of CNS alternatives that can be widely applied.
      • 04.1302 Confidential ADS-B: A Lightweight, Interoperable Approach Brandon Burfeind () Presentation: Brandon Burfeind - Sunday, March 3th, 04:55 PM - Amphitheatre
        ADS-B technology offers significant safety and efficiency benefits to the growing worldwide air transport industry. Its use is widespread and continues to grow as countries near or pass their equipage deadlines. As an interoperable extension of air traffic control radar beacon system (ATCRBS) and Mode S, Mode S-ES is a widely used ADS-B protocol which is void of security features generally found in modern information transmission systems. The historical and future requirements for interoperability among air surveillance systems also cause difficulty in implementing modern security technology. Many proposals exist for ADS-B security protocols which have sound technology but sacrifice interoperability. By decomposing security principles to focus only on the requirement for confidentiality, we devise a confidential subprotocol for Mode S-ES which is lightweight and interoperable while using industry standard cryptography. The use of format preserving encryption (FPE) with unidirectional asymmetric cryptography allows users who require confidentiality to fully participate in ADS-B without impacting those who do not.
      • 04.1304 An Overview of Current and Proposed Communication Standards for Large Deployment of UAS Rene Wuerll (Friedrich-Alexander-Universität Erlangen-Nürnberg) Presentation: Rene Wuerll - Sunday, March 3th, 09:00 PM - Amphitheatre
        Current public, private, and military communication systems, like conventional terrestrial and satellite phone data communication systems, have never been designed to provide connectivity to Unmanned Aircraft Systems (UASs) in very large numbers. UASs need not only to communicate, but require ubiquitous coverage and secure data links by design, catapulting them to the forefront of demanding communication systems. It is shown that current communication systems are neither designed, nor capable to handle the assumed growth of Unmanned Aircraft (UA) and that their routing, security, data rate, and range are not optimized for UAS flight characteristics. The presentation gives an overview of the communication standards in development and their focus area selected by their standardization bodies. The standards are investigated regarding whether they sufficiently address the needs arising from the predicted numbers of UA and are suited to enable a broad set of use cases. In particular, the new proposed schemes are examined on the physical (PHY) and medium access (MAC) layers. It is differentiated between communication for Command and Control (C2), also termed Control and Non-payload Communication (CNPC) in IEEE and ITU, communication for cooperative surveillance, and payload communication. A brief intro to routing algorithms , emphasizing on Mobile Ad-hoc Networks (MANETs), Vehicular Ad-hoc Networks (VANETs) and their relation to Flying Ad-hoc Networks (FANETs) is provided. These networks are primary means for establishing connectivity between UAs, but also between UAs and ground stations. Ideas for upgrading current communication systems to better suit the communication needs of UAS are presented. The most promising short term candidate for UAS communication is LTE. Yet, it is argued that new communication standards are necessary, not only considering 5G, to enable broad use cases of UASs.
      • 04.1306 Assessing the ADS-B OpenSky Network to Support Building a Low Altitude Encounter Model Andrew Weinert (MIT Lincoln Laboratory), Ngaire Underhill (), Ashley Wicks () Presentation: Andrew Weinert - Monday, March 4th, 04:30 PM - Amphitheatre
        With the integration of unmanned aircraft systems into the U.S. National Airspace System, low altitude regions are being stressed in historically new ways. The FAA must understand and quantify the risk of UAS collision with manned aircraft during desired low altitude unmanned operations in order to produce regulations and standards. A key component of these risk assessments are statistical models of aircraft flight. Previous risk assessments used models for manned aircraft based primarily on Mode C-based secondary surveillance radar observations. However, these models have some important limitations when used at low altitude. We demonstrate a methodology for developing statistical models of low altitude manned flight or applicable at low altitudes that leverages the OpenSky Network, a crowdsourced ADS-B receiver network that provides open access to the aircraft data, and the FAA aircraft registry, an open database of registered aircraft. Unlike Mode C surveillance, a key advantage to this method is the availability of necessary metadata to distinguish between different types of low altitude aircraft. For example, previous models did not discriminate a large commercial aircraft transiting to higher altitudes from low altitude or small general aviation aircraft cruising at low altitudes. We use an aircraft’s unique Mode S address to correlate ADS-B reports with aircraft type information from the FAA registry. We filter surveillance data and statistically characterize the low altitude airspace based on aircraft type, performance, and location. Lastly, we leverage the characterization and aircraft tracks to develop a Dynamic Bayesian Network that models the behavior of low altitude manned aircraft, an extension of previous aircraft modeling approaches that have employed Bayesian networks. By sampling representative trajectories from the Bayesian network, we can model encounters between manned and unmanned aircraft at low altitudes to assess collision risk, a key supporting technology to support safe integration of unmanned aircraft.
      • 04.1307 Micro-UAV Classification from RF Fingerprints Using Machine Learning Techniques Martins Ezuma (North Carolina State University), Fatih Erden (North Carolina State University), Chethan Anjinappa (NCSU), Ozgur Ozdemir (NCSU), Ismail Guvenc () Presentation: Ismail Guvenc - Monday, March 4th, 04:55 PM - Amphitheatre
        Abstract—This paper focuses on the detection and classification of micro-unmanned aerial vehicles (UAVs) using radio frequency (RF) fingerprints of the signals transmitted from the controller to the micro-UAV. In the detection phase, raw signals are split into frames and transformed into the wavelet domain to remove the bias in the signals and reduce the size of data to be processed. A naive Bayes approach, which is based on Markov models generated separately for UAV and non-UAV classes, is used to check for the presence of a UAV in each frame. In the classification phase, unlike the traditional approaches that rely solely on time-domain signals and corresponding features, the proposed technique uses the energy transient signal. This approach is more robust to noise and can cope with different modulation techniques. First, the normalized energy trajectory is generated from the energy-time-frequency distribution of the raw control signal. Next, the start and end points of the energy transient are detected by searching for the most abrupt changes in the mean of the energy trajectory. Then, a set of statistical features are extracted from the energy transient. Significant features are selected by performing neighborhood component analysis (NCA) to keep the computational cost of the algorithm low. Finally, selected features are fed to several machine learning algorithms for classification. The algorithms are evaluated experimentally using a database containing 100 RF signals from each of 14 different UAV controllers. The signals are recorded wirelessly using a high-frequency oscilloscope. The data set is randomly partitioned into training and test sets for validation with the ratio 4:1. 10 Monte Carlo simulations are run and results are averaged to assess the performance of the methods. All the micro-UAVs are detected correctly and an average accuracy of 96.3% is achieved using the k-nearest neighbor (kNN) classification. Proposed methods are also tested for different signal-to-noise ratio (SNR) levels and results are reported.
      • 04.1309 UAV Communications, Navigation and Surveillance: A Review of Potential 5G and Satellite Systems Nozhan Hosseini (University of South Carolina), Hosseinali Jamal (University of South Carolina), David Matolak (University of South Carolina), Jamal Haque (Honeywell) Presentation: Jamal Haque - Monday, March 4th, 05:20 PM - Amphitheatre
        Drones, unmanned aerial vehicles (UAVs), or unmanned aerial systems (UAS) are expected to be an important component of 5G/beyond 5G (B5G) communications. This includes their use within cellular architectures (5G UAVs), in which they can facilitate both wireless broadcast and point-to-point transmissions, usually using small UAS (sUAS). Allowing UAS to operate within airspace along with commercial, cargo, and other piloted aircraft will likely require dedicated and protected aviation spectrum at least in the near term, while regulatory authorities adapt to their use. The command and control (C2), or control and non-payload communications (CNPC) link provides safety critical information for the control of the UAV both in terrestrial-based line of sight (LOS) conditions and in satellite communication links for so-called beyond LOS (BLOS) conditions. In this paper, we provide an overview of these CNPC links as they may be used in 5G and satellite systems by describing basic concepts and challenges. We review new entrant technologies that might be used for UAV C2 as well as for payload communication, such as millimeter wave (mmWave) systems, and also review navigation and surveillance challenges. A brief discussion of UAV-to-UAV communication and hardware issues are also provided.
  • 5 Observation Systems and Technologies Ifan Payne (Magdalena Ridge Observatory) & Gene Serabyn (Jet Propulsion Laboratory) & J. Kent Wallace (Jet Propulsion Laboratory)
    • 05.01 Space Based Optical Systems and Instruments Ryan Mc Clelland (NASA Goddard Space Flight Center) & Bogdan Oaida (Jet Propulsion Laboratory, California Institute of Technology)
      • 05.0101 Modular Inflatable Composites for Large Space Observatories Aman Chandra (Arizona State University), Jekan Thangavelautham (University of Arizona) Presentation: Jekan Thangavelautham - Monday, March 4th, 04:30 PM - Dunraven
        There is an ever-growing need to construct large space telescopes and structures for observation of exo-planets, asteroids in the main-belt and NEOs. Space observation capabilities could potentially be revolutionized by structures spanning several meters in size. Of particular interest are star-shades for imaging distant and high-resolution large aperture telescopes. Such structures efficient load bearing features and controllable precision surfaces. A promising approach to achieve high compaction for large surface areas is by incorporating compliant materials or gossamers. For most applications, gossamer structures require supporting stiffening structures to improve accuracy but this comes at the cost of reduced packing efficiency. Structural design strategies that maximize the use of gossamers are required to fully harness their potential. Our present work focuses on such a strategy using inflatable membranes. We introduce a methodology to investigate large structural assemblies of modular inflatable units stiffened pneumatically using inflation gas. Our work shows that such units assembled into composite structures can yield desirable characteristics. Further, modifying tension and geometry of such units could be used for localized tuning of the structure thereby reducing the need for rigid support structures. Our studies focus on two separate structural requirements. The first is efficient load bearing and distribution. Such structures do not need high precision surfaces but the ability to efficiently and reliably transmit large loads. Applications include deployable drag devices for atmospheric maneuvering. The second are structures with precision surfaces for optical imaging and high gain communications. A structural analysis strategy using discrete finite elements has been developed to simulate the assembled behavior of modular units. Our analysis leads to an understanding of the extent to which inflatables can be used to create large space structures.
      • 05.0104 Camera Modeling, Centroiding Performance, and Geometric Camera Calibration on ASTERIA Christopher Pong (), Matthew Smith (Jet Propulsion Laboratory) Presentation: Christopher Pong - Monday, March 4th, 04:55 PM - Dunraven
        The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) is a 10-kg, 6U CubeSat in low-Earth orbit that was able to achieve subarcsecond pointing stability and repeatability. To date, this is the best pointing on a spacecraft of its size. This presentation will analyze various aspects of the performance of its key piece of hardware—the payload. First, a model of the optics and imager, which is used to simulate stellar images, will be presented. The imager parameters used in this model were derived from simple ground measurements. Next, a centroiding algorithm is provided and used on the simulated images to predict centroiding performance. These results will be shown to match on-orbit telemetry of centroiding performance, validating the modeling approach. This paper will then describe an approach for and results of a geometric camera calibration algorithm to estimate the focal length, distortion, and alignment parameters. The modeling, analyses, and results presented provide key information that can be used in a time-domain pointing simulation or a frequency-domain pointing error analysis.
      • 05.0105 Effects of Errors on Target Motion Compensation for Optical Imagers in Flyby Trajectories Alyssa Ralph (California Polytechnic State University), Bogdan Oaida (Jet Propulsion Laboratory, California Institute of Technology) Presentation: Alyssa Ralph - Monday, March 4th, 05:20 PM - Dunraven
        For flyby spacecraft, effects of predicted orbital determination errors, pointing accuracy error, and timing errors are exacerbated by use of target motion compensation tactics to varying degrees. A Monte Carlo simulation was employed to determine trends in smear and required target motion capabilities when such errors are applied to various combinations of hardware and flyby geometry for a selection of Jovian and Saturnian moons of exploratory interest. Results for a variety of pixel sizes, image integration times, hyperbolic excess velocities, and altitudes are presented in terms of “line error,” a metric quantifying pixel distortion in the along-track direction. Scenarios are compared to show variation in smear sensitivity. Results from the simulation can inform mission planning, hardware, and operational requirements for a range of potential missions.
    • 05.02 Ground Based Telescopes, Instruments and Technologies Stefan Martin (Jet Propulsion Laboratory)
      • 05.0201 The History and Development of the Magdalena Ridge Observatory Interferometer. Ifan Payne (Magdalena Ridge Observatory) Presentation: Ifan Payne - Sunday, March 3th, 09:50 PM - Lamar/Gibbon
        In terms of relative resolution and sensitivity the Magdalena Ridge Observatory Interferometer (MROI) will arguably be the most powerful optical telescope on earth; with greater resolution than the Hubble Space Telescope (HST) and greater than that of the three much hyped 30-meter class telescopes that are currently in development (ELT, TMT, GMT). The sensitivity of the MROI also far exceeds (by a factor of 10 to 100 times) that of other high resolution interferometers such as CHARA, NPOI and the European VLTI. This paper traces the development of the MROI from the creation of the Langmuir Atmospheric Laboratory on Magdalena Ridge in South Central New Mexico, through the establishment of the Congressionally designated research site, to the present day. The gift of a declassified 2.4-meter primary mirror, originally intended for space surveillance, led to the design of a 3-element optical interferometer then in 2004, with the signing of a memorandum of agreement with the University of Cambridge, the 3-element array was redesigned as an array of 10 x 1.4-meter optical telescopes intended to be the first of the third generation of sparse array optical interferometers. Finally, the paper will recount the development of that 10-element array and, owing to changes in Congress, the retirement of a senior Senator, and the subsequent lack of funding, it’s rescue from near extinction and the current state of the development.
    • 05.03 Exoplanet Instruments, Missions and Observations William Danchi (NASA Goddard Space Flight Center)
      • 05.0301 JWST Overview and Successful Operation of the Cryo-Vac Test at NASA JSC during Hurricane Harvey Sang Park (Smithsonian Astrophysical Observatory) Presentation: Sang Park - Thursday, March 7th, 08:30 AM - Lake/Canyon
        The JWST Optical Telescope Element (OTE) assembly is the largest optically stable infrared-optimized telescope. The primary mirrors, secondary mirror, and the Aft Optics Sub-systems (AOS) are designed to be passively cooled and operate at near 45K. This paper describes the JWST cryogenic test program, focusing on the series of integrated ‘Pathfinder’ cryogenic vacuum tests and finally performing the cryo-vac test of the Flight Optical Telescope Element mated with the Science Instruments as an integrated assembly (OTIS). The JWST OTIS cryo-vac was carefully planned, designed to safely manage numerous challenging risks, and executed in a highly-orchestrated operation. Although the OTIS test was operated and on-schedule as planned, the mother-nature provided an extreme challenge in the form of Harvey, a Category-4 Hurricane. Presented in this paper is an overview of the in-situ test operations and innovative solutions developed in real time to maintain the flight hardware safety with dwindling supplies of consumable materials, such as Liquid Nitrogen, while continuing with the cryo-vac test in the midst of one of the largest natural disaster.
      • 05.0303 Overcoming the Tradeoff between Efficiency and Bandwidth for Vector Vortex Waveplates Nelson Tabiryan (BEAM Engineering for Advanced Measurements Co.) Presentation: Nelson Tabiryan - Thursday, March 7th, 08:55 AM - Lake/Canyon
        Vector vortex waveplates offer distinct advantages compared to conventional light blocking components for coronagraphs due to their continuous structure, thinness, and transparency. They allow high contrast over a broad band in any spectral region for which the available anisotropic optical materials are transparent. We present opportunities of reducing in-band leakage of vector vortex waveplates to <0.001% level, and improving the tradeoff between the spectral bandwidth and efficiency. Comparative analysis of different architectures of vector vortex waveplates is performed.
      • 05.0304 The LBTI HOSTS Project: Instrumentation, Observations, and Survey Results William Danchi (NASA Goddard Space Flight Center) Presentation: William Danchi - Thursday, March 7th, 09:20 AM - Lake/Canyon
        The Large Binocular Telescope Interferometer (LBTI) is a stellar interferometer consisting of two 8.4-m apertures on a 14.4 m baseline on a common mount at Mt. Graham, Arizona. The Hunt for Observable Signatures of Terrestrial Systems (HOSTS) is a NASA key project for the LBTI surveying the warm and hot dust in the inner regions of planetary systems, near the habitable zone (HZ) and closer in, commonly described as being `exo-zodiacal,' analogous to the zodiacal light in our Solar System. The presence of large amounts of dust in the HZs of nearby stars poses a significant challenge for target selection and planning of future exo-Earth imaging missions. The HOSTS survey on the LBTI is designed to determine typical exozodi levels around a sample of nearby, bright main sequence stars. The LBTI operates in a nulling mode in the mid-infrared spectral window (8-13 m), in which light from the two telescopes is coherently combined with a 180-degree phase shift between them, producing a dark fringe at the location of the target star. In doing so the starlight is greatly reduced, increasing the contrast, analogous to a coronagraph operating at shorter wavelengths. The LBTI is a unique instrument, having only three warm reflections before the starlight reaches cold mirrors, giving it the best photometric sensitivity of any interferometer operating in the mid-infrared. It also has a superb Adaptive Optics (AO) system giving it Strehl ratios greater than 98% at 10 m. Thus, nulling interferometry suppresses the bright stellar light and allows for the detection of faint, extended circumstellar dust emission. In this paper we present statistical results from 38 individual stars. We provide important new insights into the incidence rate, typical levels, and origin of HZ dust around main sequence stars. Our overall detection rate is 23%. While the inferred occurrence rates are comparable for early type and Sun-like stars, but decrease from [71 (+11/-20)]% for stars with previously detected mid to far infrared excess to [11 (+9/-4)]% for stars without such excess, confirming earlier results at high confidence. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 11.5 zodis (95% confidence) for all stars without cold dust and of 16 zodis when focussing on Sun-like stars without cold dust. We find first hints of a bimodal distribution where some stars have high HZ dust levels but the majority have dust levels below our sensitivity. Our results demonstrate the strength of LBTI for vetting potential targets for future exo-Earth imaging missions.
      • 05.0305 LUVOIR Thermal Architecture Overview and Enabling Technologies for Picometer-Scale WFE Stability Sang Park (Smithsonian Astrophysical Observatory) Presentation: Sang Park - Thursday, March 7th, 09:45 AM - Lake/Canyon
        The Large UV/Optical/IR Surveyor (LUVOIR) is one of four Astro2020 Decadal Survey Missions, a concept for ‘flag-ship’ class space-borne observatory, operating across the multi-wavelength UV/Optical/NIR spectra. An Optical Telescope concept being considered is the segmented primary mirror architecture with composite backplane structure. In order to achieve the high-contrast imaging required to satisfy the primary science goals of this mission would require a pico-meter wavefront RMS stability over a wavefront control time step, a milli-Kelvin level thermometry sensing and control, and near-zero CTE materials. The LUVOIR primary mirror segment assemblies and composite backplane support structure require active thermal management to maintain operational temperature during flight operations. Furthermore, the active thermal control must be sufficiently stable to prevent time-varying thermally induced structure distortions to minimize optical aberrations. This paper describes a Thermal System Architecture of 2 concepts considered for the LUVOIR decadal study, and a systematic approach to developing a thermal architecture of modular composite sections of the mirror support structure and primary mirror segment assemblies.
      • 05.0309 Overview of the Habitable Exoplanet Observatory (HabEx) Concept Architecture Stefan Martin (Jet Propulsion Laboratory), Gary Kuan (Jet Propulsion Laboratory) Presentation: Stefan Martin - Thursday, March 7th, 10:10 AM - Lake/Canyon
        The Habitable Exoplanet Observatory (HabEx) is one of four large mission studies commissioned by NASA for the 2020 Decadal Survey in Astrophysics. HabEx has identified three driving science goals: 1) to seek out nearby worlds and explore their habitability, 2) to map out nearby planetary systems and understand the diversity of the worlds they contain, and 3) to enable new explorations of astrophysical systems from our solar system to galaxies and the universe by extending our reach in the UV through near-IR. To achieve these goals, the HabEx study has baselined a space telescope at Sun-Earth L2, with a 4 m aperture and four science instruments – a coronagraph, a starshade, a high resolution UV spectrograph, and a multi-purpose, wide-field camera.
      • 05.0310 The Spectral Calibration of Verve Judah Van Zandt (University of Notre Dame), J. Kent Wallace (Jet Propulsion Laboratory), Gene Serabyn (Jet Propulsion Laboratory) Presentation: Judah Van Zandt - Thursday, March 7th, 04:30 PM - Lake/Canyon
        This paper describes the process of spectrally calibrating a high resolution fiber-fed echelle spectrometer, designed to achieve radial velocity measurements at 10 cm/s precision. The 10 cm/s goal is motivated by the fact that Earth induces a radial velocity of this order on the Sun, making it the expected threshold for detecting planets similar to Earth in size and orbital distance elsewhere in the galaxy.
      • 05.0311 Origins Space Telescope: Mid-Infrared Transit Spectroscopy for the Detection of Bio-Signatures Johannes Staguhn (Johns Hopkins University & NASA Goddard Space Flight Center) Presentation: Johannes Staguhn - Thursday, March 7th, 10:35 AM - Lake/Canyon
        The discovery of the Trappist-1 system, which consists of an ultra cool M-dwarf star orbited by 7 planets, 3 of which are located in the habitable zone, has demonstrated that these types of planetary systems around dwarf stars are very common. Such systems are well suited for the study of exoplanets. In particular the search for bio-signatures in the atmosphere of planets in the habitable zone around M-stars will be a high-priority science goal of future space missions. The mid-infrared (mid-IR) band between 3 and 15 microns is probably the best available band for this science, because the band contains spectral lines of methane, ozone, and nitrous oxide. The coexistence of those in a planet's atmosphere would be a very strong indicator for life on the planet. The Origin Space Telescope's (OST) Mid-IR transit spectrometers will be the instrument of choice to detect these bio-signatures in exoplanets around M-dwarfs. However, current mid-IR detectors are based on impurity band conduction (IBC) devices such as Si:As detectors, which have significant problems with stability. As a result, those detectors are not expected to provide the required stability of ~ 5 ppm needed for a reliable detection of the aforementioned spectral lines. While efforts are under way to improve IBC detectors, it is unclear how far the performance can be improved. We describe alternative detector technologies and a calibration system we we are funded to demonstrate, which in combination promise to achieve the required stability.
      • 05.0312 Evaluating the LUVOIR Coronagraph Sensitivity to Telescope Aberrations Roser Juanola Parramon (NASA - Goddard Space Flight Center), Neil Zimmerman (), Tyler Groff (NASA - Goddard Space Flight Center), Matthew Bolcar (NASA Goddard Space Flight Center), Maxime Rizzo (NASA - Goddard Space Flight Center) Presentation: Roser Juanola Parramon - Thursday, March 7th, 11:00 AM - Lake/Canyon
        Direct imaging of exoplanets in their habitable zone is extremely challenging due to two main factors: the proximity of the planet to the parent star and the flux ratio between the planet and the parent star, usually to the order of 10^-10 in the visible. Future missions like the Large UV-Optical-Infrared (LUVOIR) Surveyor and the Habitable exoplanet Imaging Mission (HabEx) require large apertures and coronagraphs with active wavefront control to be able to suppress the starlight so faint planets can be detected and characterized adjacent to their parent star. The Extreme Coronagraph for Living Planet Systems (ECLIPS) is the coronagraph instrument on the LUVOIR Surveyor mission concept. The Apodized Pupil Lyot Coronagraph (APLC) is one of the baselined mask technologies to enable 10^-10 contrast observations in the habitable zones of nearby stars. The LUVOIR concept uses a large, segmented primary mirror (8-15 meters in diameter) to meet its scientific objectives. For such an observatory architecture, the coronagraph performance depends on active wavefront sensing and control and metrology subsystems to compensate for errors in segment alignment (piston and tip/tilt), secondary mirror alignment, and global low-order wavefront errors. For the LUVOIR-A architecture (15m obscured telescope), we evaluate the sensitivity to segment-to-segment tip/tilt, piston, power (focus), astigmatism, coma, trefoil and spherical errors, and to errors induced by misalignment of the secondary mirror. Here we present the latest results of the simulation of these effects and discuss the achieved contrast for exoplanet detection and characterization under these circumstances.
      • 05.0314 The Large UV/Optical/Infrared (LUVOIR) Surveyor: Decadal Mission Study Update Jason Hylan (NASA - Goddard Space Flight Center), Matthew Bolcar (NASA Goddard Space Flight Center), James Corsetti (NASA - Goddard Space Flight Center), Tyler Groff (NASA - Goddard Space Flight Center), Andrew Jones (NASA - Goddard Space Flight Center), Bryan Matonak (), Sang Park (Smithsonian Astrophysical Observatory), Garrett West (NASA - Goddard Space Flight Center), Kan Yang (NASA Goddard Space Flight Center), Neil Zimmerman () Presentation: Jason Hylan - Thursday, March 7th, 11:25 AM - Lake/Canyon
        The Large Ultraviolet / Optical / Infrared Surveyor (LUVOIR) is one of four large mission concept studies commissioned by NASA for the 2020 Decadal Survey in Astronomy and Astrophysics. LUVOIR’s science objectives, set by the LUVOIR Science and Technology Definition Team (STDT), include the direct imaging and spectral characterization of habitable exoplanets around sun-like stars, the study of galaxy formation and evolution, the exchange of matter between galaxies, star and planet formation, and the remote sensing of Solar System objects. This presentation provides an overview of and an update on the two mission concepts for LUVOIR ranging from an 8m off-axis to a 15m on-axis segmented aperture.
      • 05.0315 Modern Wavefront Control for Space-based Exoplanet Coronagraph Imaging He Sun (Princeton University), N. Jeremy Kasdin (Princeton University) Presentation: He Sun - Thursday, March 7th, 04:55 PM - Lake/Canyon
        Direct imaging of earth-like exoplanets is one of the most timely and important scientific endeavours for future large space telescopes. Typically, an earth-like exoplanet is roughly a billion times dimmer than its host star, so the key for exoplanet imaging is to create extremely high contrast observation regions in the telescope's image plane. One approach to achieving this goal is a cornagraph together with wavefront control, where the coronagraph is used to suppress the diffracted starlight and the wavefront control is used to cancel the wavefront aberrations. In this paper, we present a brief survey of the modern wavefront control techniques for a space-based coronagraph instrument, from the speckle nulling feedback controller to newly developed learning-based controllers. We also describe our implementation of all these controllers on NASA's next large space telescope, the Wide Field Infrared Survey Telescope (WFIRST), to compare their advantages and limitations.
      • 05.0317 The WFIRST CGI Integral Field Spectrograph: Requirements and Performance Predictions Tyler Groff (NASA - Goddard Space Flight Center), Neil Zimmerman (), Maxime Rizzo (NASA - Goddard Space Flight Center), Michael Mc Elwain (NASA Goddard Space Flight Center) Presentation: Tyler Groff - Thursday, March 7th, 05:20 PM - Lake/Canyon
        The WFIRST coronagraphic instrument (CGI) will demonstrate exoplanet spectroscopy using an integral field spectrograph (IFS). The CGI IFS, being designed and built at Goddard Space Flight Center, has a spectral resolution of R50 and is designed to accommodate a 20% bandpass spanning 600-970 nm. The IFS is principally targeting the abundance of Methane features, with the primary coronagraph band being centered around 770nm. Key to the performance estimates are the achievable signal-to-noise (SNR) ratios and the stability of the microspectra over the course of tens and hundreds of hours. As a technology demonstration for CGI, the ability to close a wavefront control loop around the IFS, maintain a stable dark hole, and provide time resolved data that simultaneously spans spatial and spectral dimensions are crucial demonstrations for future observatories. The IFS is optimized both for coronagraphs and science observations with a potential future starshade. We highlight how the long duration observations, and requirements for both starshades and coronagraphs drive the IFS requirements and the calibrations required both on-orbit and on the ground. We also provide further detail on the optomechanical design, its stability based on thermal and structural predictions, anticipated performance, and operations concept of the CGI IFS. The impact of these performance metrics are projected into simulated data products, demonstrating cube extraction of noisy images and the subsequent planet spectrum that can be extracted from them. These demonstrations and performance predictions are key to future missions such as LUVOIR and HabEx, whose principal science case relies on efficient spectroscopy of exoplanets.
    • 05.04 Atmospheric Turbulence: Propagation, Phenomenology, Measurement, Mitigation Noah Van Zandt (Air Force Research Laboratory) & Jack Mc Crae (Air Force Institute of Technology)
      • 05.0401 Statistics of Target-induced Array Tilt in Coherently Combined Laser Array Engagements Milo Hyde (Air Force Institute of Technology) Presentation: Jack Mc Crae - Sunday, March 3th, 04:30 PM - Lamar/Gibbon
        The array tilt induced by a rough speckle target illuminated by an optical phased array is investigated. Assuming that the field incident on the target is the focused array field, the mutual intensity of the field backscattered to the array is derived. The array tilt variances and probability density functions are then computed from many realizations of the received speckle field generated using the aforementioned mutual intensity. The array tilt statistics for 7, 19, and 37 element hexagonal arrays are presented and discussed. Holding fill factor constant, it is found that the array tilt variance generally decreases as the array size increases.
      • 05.0402 Investigating the Outer Scale of Atmospheric Turbulence with a Hartmann Sensor Jack Mc Crae (Air Force Institute of Technology), Santasri Bose Pillai (Air Force Institute of Technology), Christopher Rice (), Steven Fiorino (AFIT) Presentation: Jack Mc Crae - Sunday, March 3th, 04:55 PM - Lamar/Gibbon
        A Hartmann Turbulence Sensor (HTS) system has been used to study the outer scale of turbulence. The atmospheric turbulence power spectrum is usually presumed to obey the Kolmogorov power law within some inertial range, while at spatial frequencies outside this range, the power spectrum is expected to fall away from this curve. The outer scale is the spatial frequency where the low frequency side of this roll-off occurs. In length units the outer scale is just the inverse of this spatial frequency. In the free atmosphere, this outer scale is presumed to be on the order of a hundred meters, but near the ground, the outer scale is expected to be on the order of the height above ground. The HTS used for this study has an aperture of 16” and employed a beam path which was around 5’ above the ground, thus the effects of the outer scale are expected to be minimal within the telescope aperture. However by relying on the cross wind to move turbulence across the telescope aperture much longer baselines can be achieved and outer scale effects can be sought. The presumption that the dominant temporal variation in turbulence is wind driven translation is called the Taylor Frozen Flow Hypothesis. When an outer scale is introduced into the Kolmogorov power spectrum the resulting power spectrum is called the von Kármán power spectrum. The wave structure functions due to these two power spectra are very different, as the Kolmogorov spectrum leads to a structure function which increases without bound as the separation between points increases, whereas the structure function due to the von Kármán spectrum rolls-over near the outer-scale and becomes constant. Unfortunately, the structure function itself isn’t measured by the HTS. Instead, the HTS can observe the tilt differences between subapertures separated in space or time. The Taylor Frozen Flow Hypothesis can then be used to switch between time and space. It is clear in the experimental data that this presumption is largely correct for some of the cases studied. Some of the data sets were collected with the fortuitous condition that the wind was approximately perpendicular to the path, with product between the wind speed and frame rate nearly matching the subaperture spacing. The expected differential tilt variance between subaperture pairs rolls over as the subaperture spacing increases and approaches a constant value for both the Kolmogorov and von Kármán power spectra, however in the case of the von Kármán spectrum this roll-over happens more clearly and the differential tilt variance exhibits a broad weak peak near the outer scale. Also, in the case of the von Kármán spectrum the constant value approached is smaller. Comparisons between measured differential tilt variances and those predicted by theory allows some estimates to be made about the size of outer scale.
      • 05.0403 Wave Optics Modeling of Solar Eclipse Shadow Bands Hanyu Zhan (New Mexico State University), David Voelz (New Mexico State University) Presentation: Santasri Bose Pillai - Sunday, March 3th, 05:20 PM - Lamar/Gibbon
        Just preceding and following the occurrence of a total solar eclipse, thin, wavy ribbons of light can be seen on the ground. These shadowy patterns known as “shadow bands” have an interesting historical story with regard to the explanation of their cause, but it is now generally accepted that they are a result of the sun’s light propagating through atmospheric turbulence as the solar crescent thins to a narrow filament. The narrowing of the source increases the spatial coherence of the light reaching the earth and this, combined with refraction and diffraction associated with turbulence, produces visible intensity variations on the ground. Previous studies have shown that the bands appear to move in a direction perpendicular to their elongation and their contrast increases and band spacing decreases as a function of decreasing wavelength. In addition, as totality approaches the bands become more linear and aligned, their spacing decreases and their contrast increases. Using weak scintillation theory and an atmospheric turbulence model, Codona [Astronomy and Astrophysics 164(2), 415-427, 1986] presented a theoretical investigation that explains these observed features and suggests the turbulence mainly responsible for shadow band is found to be within the bottom 2-3 kilometers of the atmosphere. In the work presented here, we propose a novel approach to model the shadow band phenomena using a numerical wave optics simulation where atmospheric turbulence is modeled with a set of phase screens. A crescent-shaped source is modeled as many independent point radiators and the field from each point is assumed to be a plane wave when it reaches the earth’s atmosphere. These waves are individually propagated with a split-step Fresnel diffraction algorithm through phase screens that model the lower part of the atmosphere and the results are combined incoherently at a ground plane. The simulation produces intensity patterns, structures, motion and evolution of shadow bands that agree well with Codona’s theory and with actual observations during an eclipse. For example, the band orientation is parallel with the crescent and as the crescent narrows the patterns become more linear and organized while the contrast increases. This work is significant in being the first report of the modeling of the shadow band phenomena using a numerical wave optics simulation. The simulation is useful for studying the effects of specific atmospheric conditions on shadow bands but the approach can also be applied to other problems involving extended sources observed through turbulence.
      • 05.0404 Estimation of Fried’s Coherence Diameter from Differential Motion of Features in Time-lapse Imagery Santasri Bose Pillai (Air Force Institute of Technology), Jack Mc Crae (Air Force Institute of Technology), Steven Fiorino (AFIT) Presentation: Santasri Bose Pillai - Sunday, March 3th, 09:00 PM - Lamar/Gibbon
        At the Air Force Institute of Technology, we have developed a technique to estimate atmospheric turbulence parameters from the turbulence-induced random, differential motion of features in the time-lapse imagery of a distant target. The variance of differential motion is a path-weighted integral of the refractive index structure constant, Cn2. The path weighting functions drop to zero at either ends of the path, their peak locations depending on feature sizes and separations. These weighting functions form a rich set and can be linearly combined to approximate a desired weighting function, such as that of a scintillometer or Fried’s coherence diameter, r0. The time-lapse measurements can thus mimic the measurements of any turbulence measuring instrument. Since this is a phase-based technique, it has the potential to estimate turbulence over long paths where irradiance based techniques suffer from saturation issues. The method has been validated earlier against scintillometer measurements over a 7 km path. In the present work, the method is used to obtain a direct estimate of r0 from the time-lapse imagery of a LED array. The r0 estimates are compared to those obtained from a co-located turbulence profiling instrument.
      • 05.0405 Assessing Free-Space Optical Communications through 4D Weather Cubes Steven Fiorino (AFIT), Santasri Bose Pillai (Air Force Institute of Technology), Josiah Bills (Radiance Technologies), Brannon Elmore (Air Force Institute of Technology), Jaclyn Schmidt (Air Force Institute of Technology), Kevin Keefer () Presentation: Jaclyn Schmidt - Sunday, March 3th, 09:25 PM - Lamar/Gibbon
        This study investigates use of a novel data aggregation and interrogation tool, 4D Weather Cubes, and High Performance Computing (HPC) to further enlighten the ongoing debate regarding the potential for terrestrial free space optical (FSO) communications and benefits that might accrue on implementation of hybrid FSO architectures with a millimeter wave backup link. The 4D Weather Cubes were originally developed to accurately assess Directed Energy weapons and sensor performance (at any wavelength/frequency or spectral band) in the absence of field test and employment data. 4D Weather Cubes are the product of efficient processing of large, computationally intensive, National Oceanic and Atmospheric Administration (NOAA) gridded numerical weather prediction (NWP) data coupled to the verified and validated Laser Environmental Effects Definition and Reference (LEEDR) atmospheric characterization and radiative transfer code. The 4D Weather Cubes, inclusive of both conventional meteorological parameters, as well as optical features such as atmospheric transmission and turbulence, initialized the High Energy Laser End to End Operational Simulation (HELEEOS) propagation code. HELEEOS provided an additional tier of aggregation through development of comparative percentile performance binning of FSO communication bit error rates as a function of wide-ranging azimuth/elevation, earth-to-space uplinks. The aggregated, comparative bit error rate binning analyses for different regions, times of day and seasons are relevant to point‐to‐point as well as evolving multi‐layer wireless network concepts.
    • 05.05 Image Processing Matthew Sambora (USAF)
      • 05.0501 Hyperspectral Image Classification Based on Logical Analysis of Data Ayman Ahmed (), Sara Ibrahim (Zagazig University), Soumaya Yacout (École Polytechnique) Presentation: Ayman Ahmed - -
        In this research, we have introduced a new concept of using Logical Analysis of Data (LAD) as a new classifier for hyperspectral data. Two main points have been concluded. The first is the ability of LAD to classify material based on generated spectral bands, since we compared LAD’s classification performance with that of the convolutional neural network, or CNN. LAD demonstrated comparable performance. The other point of discussion was on the knowledge introduced by LAD during the classification process. We named a “spectral pattern” as the patterns generated by LAD to distinguish between hyperspectral classes and sub-classes; these spectral pattern(s) are unique for certain materials within the same data set, while it is different for the same material in another data set. This advantage can reduce the amount of data needed for monitoring areas. If LAD identifies class among other classes by using spectral patterns, and it did the same for other classes, there will be no need to continuously picture the whole spectral range. This may reduce the data needed. The software cbmLAD seems promising in this area and more research is now being undertaken to apply it to more hyperspectral data sets in order to validate the accuracy, the interpretability and the computation time.
      • 05.0504 Correction of Etaloning Effects in Ground-based Hyperspectral Image Cubes of Jupiter Erandi Wijerathna (New Mexico State University), Emma Dahl (New Mexico State University), David Voelz (New Mexico State University), Nancy Chanover (New Mexico State University) Presentation: Erandi Wijerathna - Wednesday, March 6th, 09:00 PM - Madison
        The New Mexico State University Acousto-optic Imaging Camera (NAIC) at the Apache Point Observatory 3.5-m telescope is collecting narrowband hyperspectral image cubes of Jupiter from 470-950 nm during the perijove passes of the Juno spacecraft. For operations prior to 2018, the focal plane used for NAIC was a 1024x1024 pixel2 backside illuminated, high quantum efficiency CCD. However, the narrowband images show evidence of “fringing”, due to “optical etaloning.” For much of our collected data, a flat-field correction successfully removes the fringing from the science images. However, for some absorption features, especially in Jupiter’s prominent CH4 bands at ~890 nm, differences in the illumination spectrum of the flat-field source and Jupiter leave residual fringing in the images. Observation of the fringe pattern in the flat-field images as a function of wavelength suggested we could assume a thickness function with a single layer involving a single reflective surface. The thickness of the sensor has a “dish-shaped” variation as a function of pixel position in addition to finely spaced surface polishing marks. Using a mathematical interference (fringe) model, we were able to solve for the 2-D physical thickness function of the CCD at each pixel by minimizing the mean square error between the fringe model and the pixel spectral data. Synthetic fringe frames were created using the 2-D thickness function and scaled with best-correction contrast values. The flat-field and Jupiter images were corrected separately for fringing with division by the synthetic fringe frames. Fringe-corrected Jupiter frames are divided by fringe-corrected flat field frames to yield the final Jupiter science images, which show little evidence of etaloning.
      • 05.0505 A Deep Learning Framework for Automatic Airplane Detection in Remote Sensing Satellite Images Wessam Hussein (MTC), Ehab Abouobaia (Military Technical College), Ahmed Hassan (mtc) Presentation: Wessam Hussein - Wednesday, March 6th, 09:25 PM - Madison
        automated object detection in high-resolution remote sensing satellite images(HRRSSI) is a proper solution for this task rather than manual detection using professional specialists. However, it is more complex due to the varying size, type, orientation, and complex background of the objects to detect. Utilizing artificial intelligence using deep learning is the state of the art technique to achieve this task. The number of labeled satellite images is limited for training a deep neural network therefore; transfer learning techniques were adopted for this task. This paper proposes a framework for airplane detection based on Convolution Neural network (CNN). Faster Region Based CNN (Faster R-CNN) framework is used to perform automatic airplane detection through transfer learning. Inception v2 is added to the network for feature extraction to enhance detection accuracy. The problem of information reduction of the objects due to the resizing of large size satellite image in test phase has been solved by adding a split layer before the input layer, together with a mosaic layer after detection output layer. Dataset is used to build and test the model is collected from Google Earth. Experimental results prove that the proposed developed model is extremely accurate for satellite images object detection.
    • 05.06 Optical Detection and Analysis for Space Situational Awareness (SSA) Michael Werth (Boeing Company)
      • 05.0602 SNR Modeling for Ground-based Daytime Imaging of GEO-satellites in the SWIR Grant Thomas (Air Force Institute of Technology) Presentation: Grant Thomas - Monday, March 4th, 09:00 PM - Dunraven
        This research outlines the expected performance and limitations of a ground-based shortwave infrared (SWIR) sensor in performance of the daytime geosynchronous satellite (GEO) custody mission with a generalized signal-to-noise ratio (SNR) approach model.
      • 05.0603 Ground-Based Optical Imaging of GEO Satellites with a Rotating Structure in a Sparse Aperture Array Michael Werth (Boeing Company) Presentation: Michael Werth - Monday, March 4th, 09:25 PM - Dunraven
        A presentation describing Michelson interferometry systems that incorporate a rotating truss into a static array of optical telescopes for imaging geostationary targets, including simulated results of u-v fill and image reconstructions
    • 05.07 Photonics and Lasers Aleksandr Sergeyev (Michigan Technological University) & David Peters (Sandia National Laboratories)
      • 05.0701 Experimental Simulations on the Laser Visualization of Flow Vortices Krishna Thakkar (SRM University), Akanksha Kesarwani (SRM Institute of Science and Technology), Karar Khan (Srm ), Rahul Sunil (SRM IST), Kannan B T (SRM Institute of Science and Technology ), Vinayak Malhotra (SRM University) Presentation: Krishna Thakkar - Wednesday, March 6th, 04:30 PM - Madison
        Vortices are a major component of turbulent flow. The dynamics of vortices depends majorly on the nozzle geometry which in turn drives the mixing properties. The stream wise vorticity drastically alters the mass entrainment of a jet, and the efficiency of this vorticity in entraining fluid increases as the jet evolves downstream. An attempt was made to study the effects of various orifice geometries under different operating flow velocities on characteristics of vortices created by smoke, using a laser visualization technique. The nozzle geometries studied include circular and non-circular (square, triangle). The characteristic features of non-circular ones include improved large and small scale mixing in low and high speed flows, and enhanced combustor performance by improving combustion efficiency, reducing combustion instabilities and undesired emissions. For square and triangular sections the effect of different angles were also observed. Further, straws and meshes were fixed inside the setup such that it ensured a uniform distribution of flow and reduced turbulence to avoid possible variation. Visualization of the flows was carried out in the vicinity of the orifice exit in order to identify flow regimes and to study coherence. The work can be utilized significantly in potential space applications of vortex dynamics in space debris removal system, injectors, HVAC (Heating, ventilation, and air conditioning), nozzles etc.
      • 05.0702 Fundamentals and Applications of Resonant Leaky-mode Photonic Lattices Robert Magnusson (University of Texas at Arlington) Presentation: Robert Magnusson - Wednesday, March 6th, 04:55 PM - Madison
        Nano- and microstructured films with subwavelength periodicity represent fundamental building blocks for a host of device concepts. Whereas the canonical physical properties are fully embodied in a one-dimensional lattice, the final device constructs are often patterned in a two-dimensional slab or film in which case we refer to them as photonic crystal slabs or metasurfaces. These surfaces are capable of supporting lateral modes and localized field signatures with propagative and evanescent diffraction channels critically controlling the response. Local Fabry-Perot and Mie mode signatures are observable by computations within the structural geometry. It is clear that these local modes have no causal effect with all key functionality provided by lateral leaky Bloch modes. The subwavelength restriction of periodicity is usually maintained for effective devices; however, it is also possible to generate interesting spectral behavior when this is not satisfied leading to unexpected device concepts. The dominant second leaky stopband exhibits many remarkable physical properties including band-edge transitions and bound states in the continuum. Multi-resonance effects are observed when Bloch eigenmodes are excited with more than one evanescent diffraction channel with the resulting spectral response clearly understood by invoking this process. In this paper, we discuss these key properties of leaky-mode lattices and present relevant device examples. These include fiber mounted resonant sensors that have been designed, fabricated and tested. Moreover, for potential aerospace applications including imaging and sensing, experimental results on wideband reflectors operating in the mid-IR spectral region spanning from 3 to 13 μm are presented along with demonstration of their design and fabrication.
    • 05.08 Microscopy for Life Detection Chris Lindensmith (Jet Propulsion Laboratory, California Institute of Technology)
      • 05.0801 Development of a Light-field Fluorescence Microscope for in Situ Life Searches in the Solar System Gene Serabyn (Jet Propulsion Laboratory), Kurt Liewer (Jet Propulsion Laboratory), Chris Lindensmith (Jet Propulsion Laboratory, California Institute of Technology), Jay Nadeau (Portland State Universty), J. Kent Wallace (Jet Propulsion Laboratory) Presentation: Gene Serabyn - Thursday, March 7th, 09:00 PM - Lake/Canyon
        To search for microbial life on Ocean Worlds, 3D imaging microscopes are needed that can rapidly examine large liquid volumes for potential signs of cellular structure and morphology. Here we describe a 3D fluorescence light-field microscope (FLFM), an emerging approach for 3D fluorescence imaging. Our ultimate goal is to combine a FLFM with a digital holographic microscope into a multi-mode lander instrument package.
      • 05.0802 A Multiwavelength Digital Holographic Microscope Architecture for Enhancing Life Detection J. Kent Wallace (Jet Propulsion Laboratory), Jay Nadeau (Portland State Universty), Manuel Bedrossian (California Institute of Technology), Gene Serabyn (Jet Propulsion Laboratory) Presentation: J. Kent Wallace - Thursday, March 7th, 09:25 PM - Lake/Canyon
        Spectral properties of living organism can provide a discriminating method for characterization. However, digital holographic microscopy (DHM), a high-resolution, volumetric imaging technique that is well-suited for examining microbial species is typically monochromatic. Thus, the spectral properties of bacteria are not probed with DHM save only for the wavelength of operation. Here we describe a new DHM instrument which enhances the method via the simultaneous recording of wavelength multiplexed holograms of the sample. This coarse spectral encoding is akin to labeling with RGB values, thereby producing colorized images of the species which enables a new dimension of characterization. This new instrument is derived from a previous architecture which has already demonstrated superior opto/mechanical stability. Herein, this novel instrument is described, and the results of experimental measurements taken with this new instrument are shown.
      • 05.0803 Digital Holographic Microscope Trades for Extant Life Detection Applications Chris Lindensmith (Jet Propulsion Laboratory, California Institute of Technology), Gene Serabyn (Jet Propulsion Laboratory), J. Kent Wallace (Jet Propulsion Laboratory), Jay Nadeau (Portland State Universty) Presentation: J. Kent Wallace - Thursday, March 7th, 09:50 PM - Lake/Canyon
        Optical microscopy is one of the key technologies needed for detection of extant life on other solar system bodies. Micro-scopic images can be used to identify the presence of cell-like objects and discriminate probable cells from other abiotic particles of similar scale through observations of morphology. Image sequences can be used to determine particle density through observation of Brownian motion, enabling discrimination of liquid-filled vesicles from solid mineral grains; non-Brownian motion that is also inconsistent with background flow can also indicate biotic particles. Phase-sensitive imaging modes allow measurement of index of refraction and can be used to image transparent cells that might otherwise require the addition of stains. Because of the likely limited energy available for replication on the moons of Jupiter and Saturn, potential unicellular life would likely be present only at very low concentrations requiring a search through substantial volumes of material at very high resolution. We have been developing digital holographic microscopes (DHM) that addresses the need for high resolution search at low concentrations. Our DHM designs provide both the sub micrometer resolution necessary to detect the smallest forms of life and the high throughput needed to do so at very low concentrations. A significant feature of the holographic recording is that all objects in a large volume can be recorded simultaneously, without the need for focus or tracking to image individual objects. We have demonstrated two promising DHM architectures for possible use in potential future life detection missions – one using conventional optics and one using gradient index optics in a “lensless” arrangement. We compare the two designs, their trade spaces, and the features that might make each preferable for specific applications.
  • 6 Remote Sensing Jordan Evans (Jet Propulsion Laboratory) & Darin Dunham (Lockheed Martin)
    • 06.01 Systems Engineering Challenges and Approaches for Remote Sensing Systems Karen Kirby (JHU-APL) & Todd Bayer (NASA Jet Propulsion Lab)
      • 06.0102 Impact of Simultaneous Movements on Perception of Safety, Workload and Task Difficulty in MRTO Maria Hagl (), Maik Friedrich (German Aerospace Center - DLR), Joern Jakobi (), Sebastian Schier Morgenthal (), Christopher Stockdale () Presentation: Maik Friedrich - Monday, March 4th, 04:30 PM - Lamar/Gibbon
        Providing air traffic service to more than one aerodrome is a key concept within Remote Tower. So-called Multiple Remote Tower Operations (MRTO) are expected to be more cost-efficient and user-friendly. On the one hand, their anticipated benefit is to maintain smaller airports that are currently non-profitable due to low traffic numbers, high staff- and tower maintenance costs. On the other hand, MTRO offer equally distributed and constant activity for air traffic controllers (ATCOs), with the expectation to lower risks of human error due to boredom or sleepiness at work. However, multiple tasking challenges arise if one ATCO needs to handle traffic at three airports simultaneously. Thus, combinations of visual, audio, vocal and haptic tasks need to be performed for more than just one location. Therefore, this paper addresses the impact of simultaneous movements on perceived safety, workload and task difficulty. Descriptive results show that with the increase of simultaneous movements, providing ATC is perceived as being more efficiency-critical, more demanding in workload and task difficulty increases as well. It was not tested if the differences were significant, since statistical conditions have not been met. Results show that no situation containing simultaneous movements was perceived as a threat to safety, good workload or the ability to provide ATC. The discussion shows why the impact of simultaneous movements might not only affect MRTO but also single remote or conventional tower environments.
      • 06.0103 Challenges and Solutions for Precision Solar Pointing on the ISS for the TSIS Instrument Patrick Brown (LASP, University of Colorado) Presentation: Patrick Brown - Monday, March 4th, 04:55 PM - Lamar/Gibbon
        The International Space Station offers an attractive platform for external payloads in many regards, but its large, complex structure is challenging for payloads that require precise, unobstructed pointing. As an instrument that measures solar irradiance on a continual basis, the TSIS payload was designed to robustly account for these ISS challenges and is now performing its mission on the ISS with great success. This presentation will first describe how TSIS was able to measure the ISS background jitter using High-rate Fine Sun Sensor data that was taken during passive solar transits through its field of view. The measurements showed that ISS jitter at the TSIS location on ELC-3 Site 5 is relatively benign with less than 4 arcseconds 1σ at frequencies less than 0.5 Hz. This value is lower than previous estimates but agrees well with recent measurements from other external payloads, including OPALS and SAGE III. Because TSIS was designed to be robust to base motion jitter, it has achieved less than 4 arcseconds 1σ of pointing error, which provides an extremely precise pointing platform for the solar irradiance measurements. The second challenging ISS characteristic is its large, complex structure that obscures solar viewing at sunrise and sunset from the zenith-facing location of TSIS. Although TSIS was able to predict solar viewing durations during the design phase with relatively high accuracy, the exact timing and causes of obscuration were difficult to predict and understand after TSIS began operating on the ISS. To aid in the understanding of blockage by ISS structure, detailed obscuration maps were created using HFSS measurements that clearly show the exact gimbal angles where blockage occurs and the specific structural features of the ISS that cause the blockage. These maps have helped TSIS to maximize its solar tracking durations each orbit, which has supported the mission in meeting its science objectives.
      • 06.0106 An Initial Analysis of the Stationkeeping Tradespace for Constellations Andris Slavinskis (Tartu Observatory/NASA Ames Research Center), Joel Mueting (NASA Ames Research Center), Sreeja Nag (NASA Goddard Space Flight Center / Ames Research Center (BAERI)) Presentation: Andris Slavinskis - Monday, March 4th, 05:20 PM - Lamar/Gibbon
        This paper presents an Orbit Maintenance Module (OMM) for Tradespace Analysis Tool for Constellations (TAT-C), a software package to explore a wide range of tradespaces to design constellations for Earth observation. As the tool is primarily meant for rapid pre-Phase A analysis, it has to be able to estimate trade-offs and overall performance parameters with simplified models on a personal computer in a reasonable time frame. The OMM estimates the secular drift of relative orbital elements between pairs of satellites due to the gravitational `J2' effects and the drift of altitude due to the atmospheric drag, and computes maneuvers to correct them. The J2 is a predominant term in the gravitational zonal harmonics which, primarily, affects the argument of perigee and the mean anomaly. We estimate the drift of these elements between pairs of satellites using a fourth-order polynomial, which is trained using machine learning and which depends on the inclination, altitude and initial angular separation in true anomaly and right ascension of the ascending node. An analytical model is used to predict the deorbiting rate depending on the initial altitude, the solar cycle, the satellite's mass, drag coefficient and area. In order to maintain the required topology of a constellation, the drift of orbital elements is compensated using emulated orbital maneuvers, when satellites breach a user-defined threshold percentage of their nominal values. We assume simple orbital maneuvers (i.e., orbit phasing and Hohmann transfer) to determine the required delta-v, propellant consumption and frequency of maneuvers. These parameters are provided as outputs of the TAT-C's OMM, which advises the user on trade-offs between performance and maintenance overhead of all enumerated constellation architectures. The maneuver metrics can be used to determine various dependent metrics, such as time available for observations, impact on total satellite mass, and mission cost.
      • 06.0109 A Framework for Heterogeneous Satellite Constellation Design for Rapid Response Earth Observations Ibrahim Sanad (University of British Columbia (UBC)), David Michelson (University of British Columbia) Presentation: Ibrahim Sanad - Monday, March 4th, 09:00 PM - Lamar/Gibbon
        Objectives and constraints of remote sensing missions are the main driver of selection the constellation orbital configurations. Improving System Response Time (SRT) of Earth Observation satellites is of significant interest for Disaster Risk Reduction (DRR) and national security applications. This performance metric leads to evolve the constellation design methods for remote sensing into a more complex phase of design, a phase of heterogeneous (nonhomogeneous) constellations that uses InterSatellite Link (ISL) between two different functional constellations, remote sensing constellation and a constellation of small satellites dedicated for command delivery and relay data back to Earth. The heterogeneous system configuration and the constellation details have a significant impact on the system availability. The availabilities are dependent on the imaging and relay constellation characteristics, e.g., altitudes, number of orbital planes & types, number of satellites per plane, etc. The best configuration of a heterogeneous system requires studying several constellation combinations. This paper introduces a framework for heterogeneous constellation system based on tradeoff analysis between different design variables and their related measure of performances.
      • 06.0110 VISIONS-3: Using Sounding Rockets and 3D Tomography to Analyze Ion Outflow Sophia Zaccarine (Embry-Riddle Aeronautical University) Presentation: Sophia Zaccarine - Monday, March 4th, 09:25 PM - Lamar/Gibbon
        VISualizing Ion Outflow via Neutral atom Sensing (VISIONS) and VISIONS-2 are sounding rocket missions with the goal of analyzing the auroral wind and cusp ion outflow us- ing low energy neutral atom (ENA) imaging at low altitudes of the ionosphere (P.I. Dr. Douglas Rowland, NASA Goddard). VISIONS-3 is the proposed follow-up mission, intended to use tomographic reconstruction with two launch vehicles. The overlap of line-of-sight regions from the two viewpoints of the sounding rockets provides boundary conditions to mathemat- ically constrain data analysis, similar to a CAT scan. Each payload will house at least two Experimental Energy Neutral Atom Imager (E-ENA) instruments, oriented to point oppo- site directions out of the rocket. A data simulation is being created to model the line-of-sight regions from each rocket to deduce the intake of energized particles by each instrument detector. This data simulation will more fully define the ben- efits of launching two rockets rather than just one, as well as to model the use of tomography. The Norway launch range was selected for the launch, with two Black Brant XII Sound- ing Rockets from Wallops Flight Facility launched between 1-3 minutes apart with a launch azimuth separation of 6-16 degrees. The launch will be during the day to analyze the poleward moving auroral forms. The significance of this re- search is that insight into our ionosphere, magnetosphere, ion outflow, and the “boiling o↵” phenomenon of our atmosphere may provide understanding of how the atmosphere of other planets (e.g. Mars) disappeared. This would provide further insight into the life cycle of planets and atmospheres. Addi- tionally, a heightened understanding of space physics could lead to the ability to predict which exoplanets may have an atmosphere and magnetic field like Earth using deep space telescopes. This presentation will focus on the mission design.
    • 06.02 Instrument and Sensor Architecture, Design, Test, and Accommodation Matthew Horner (JPL) & Keith Rosette (Jet Propulsion Laboratory)
      • 06.0201 Ocean Color Instrument Integration and Testing Susanna Petro (), David Sohl (NASA - Goddard Space Flight Center) Presentation: Susanna Petro - Sunday, March 3th, 04:30 PM - Dunraven
        This presentation shows the plans, flows, key facilities, components and equipment necessary to fully integrate, functionally test, qualify and calibrate the Ocean Color Instrument (OCI) on the Plankton, Aerosols, Clouds, and oceans Ecosystem (PACE) observatory. PACE's primary sensor, the OCI, is a highly advanced optical spectrometer that will be used to measure properties of light over portions of the electromagnetic spectrum. It will enable continuous measurement of light at finer wavelength resolution than previous NASA satellite sensors, extending key system ocean color data records for climate studies. The color of the ocean is determined by the interaction of sunlight with substances or particles present in seawater such as chlorophyll. By monitoring global phytoplankton distribution and abundance with unprecedented detail, the OCI will contribute to a better understanding of the complex systems that drive ocean ecology and it’s impacts on global fisheries. This presentation will focus on the Integration and Test (I&T) activities for OCI while it is at the NASA Goddard Space Flight Center. The OCI integration consists of assembly and alignment of the rotating telescope, electronics box integration, fixed deck assembly integration, thermal systems integration and the final assembly and testing. This I&T phase will be followed by the OCI calibration and characterization, environmental tests which include electromagnetic interference (EMI)/electromagnetic compatibility (EMC), vibration with sine sweep, acoustics, shock, thermal balance, thermal vacuum, mass properties and center of gravity. This presentation includes description of the OCI shipment and delivery to the spacecraft vendor for observatory level I&T as well as some launch preparation activities.
      • 06.0202 Overview of the TROPICS Flight Segment Andrew Cunningham (MIT Lincoln Laboratory) Presentation: Andrew Cunningham - Sunday, March 3th, 04:55 PM - Dunraven
        The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA in 2016 as part of the Earth Venture Instrument (EVI-3) program and is now in development with planned launch readiness in late 2019. The TROPICS constellation consists of six CubeSats, two in each of three low-Earth orbital planes with a nominal circular orbit of 550 km and inclination of 30\textdegree. Each CubeSat hosts a high-performance radiometer payload with twelve microwave channels, providing atmospheric temperature profiles, water vapor profiles, and rain rate. The TROPICS mission will produce rapid-refresh microwave measurements (median refresh rate of approximately 40 minutes for the baseline mission) over the Tropics that will enable observations of the entire tropical storm lifecycle. The radiometer design is similar to two other MIT Lincoln Laboratory (MIT LL) CubeSat programs, MicroMAS and MiRaTA, with improvements to meet enhanced performance requirements and longer mission life. The CubeSat bus is under contract with a commercial vendor who will integrate the MIT LL payload and their bus, and test the complete space vehicle. This paper will describe the mission, present various aspects of the payload and bus design, and describe the assembly, integration and test flow.
      • 06.0203 Omniscopic Vision for Robotic Control. Dominique Meyer (), James Strawson (), Falko Kuester (University of California, San Diego) Presentation: Dominique Meyer - Sunday, March 3th, 05:20 PM - Dunraven
        We propose a camera system that uses an array of 16 individually driven cellphone sensors that achieve a combined resolution of up 210 MegaPixels with 360 x 45 degreee coverage. This system demonstrates stereoscopic pairs which serve to easily derive depth, while maintaining a resolving power of 3 cm at 100m with a framerate of up to 30 Hz, equivalent to the human resolving power. The assembly highlights a novel vision capability for ground vehicles, where object detection and odometry is enabled for “far-ahead” planning and safe operation of vehicles. This paper illustrates design validations for the full system and test results of this camera array. We evaluate system reliability, sensing performance in high dynamic range lighting conditions, and illustrate the data handling of this data-intensive workflow. The physical system is tested in indoor and outdoor scenes with varying light conditions and with both stationary and in motion scenes. Additional array layouts with the same cameras are discussed that expand vertical FoV, explore monoscopic versions and differ in physical footprint.
      • 06.0207 Improving UAVSAR Results with GPS, Microwave Radiometry, and QUAKES Topographic Imager Andrea Donnellan (Jet Propulsion Laboratory, California Institute of Technology), Yunling Lou (Jet Propulsion Laboratory), Curtis Padgett (Jet Propulsion Laboratory), Alan Tanner (Jet Propulsion Laboratory), Brian Hawkins (), Jay Parker (Jet Propulsion Laboratory), Adnan Ansar (Jet Propulsion Laboratory), Michael Heflin (Jet Propulsion Laboratory), Ronald Muellerschoen (JPL) Presentation: Andrea Donnellan - Sunday, March 3th, 09:00 PM - Dunraven
        UAVSAR is NASA’s airborne interferometric synthetic aperture radar (InSAR) platform. The instrument has been used to detect deformation from earthquakes, volcanoes, oil pumping, landslides, water withdrawal, landfill compaction, and glaciers. It has been used to detect scars from wildfires and damage from debris flows. The instrument performs well for large changes or for local small changes. Determining subtle changes over large areas requires improved instrumentation and processing. We are working to improve the utility of UAVSAR by including GPS station position results in the processing chain, and adding a topographic imager to improve estimates of topography, 3D change, and damage. We are also exploring the benefit of microwave radiometry to mitigating error from water vapor path delay. A goal is to determine 3D tectonic deformation to millimeters per year at ~100 km plate boundary scales and to understand surface processes in areas of decorrelated radar imagery.
      • 06.0208 Estimation of Stellar Instrument Magnitudes Based on Synthetic Photometric Spectrum Rui Lu (Beijing Institute of Control Engineering) Presentation: Rui Lu - -
        —Stellar instrument magnitudes are of great importance for star trackers. Many methods have been proposed to estimate stellar instrument magnitudes so far, normally making assumption that the dependence among color indices is supposed to be in form of a linear, quadratic or fourth order polynomial fitting function, with one or multiple variables of color indices. Actually, it is not the case especially for stars of all spectral classes over the whole wavelength. Fitting methods cannot be universal, as not all spectral photometry data are available. Moreover, fitting methods may lead to large error with higher order item abandoned. In this paper a novel method of stellar instrument magnitudes computation is proposed by convolving the synthetic photometry spectrum with the optical transmission of star trackers, taking account of the photon-counting nature of modern imaging detectors. This procedure is consistent with the definition of stellar instrument magnitudes, without any assumption. As no high order item is abandoned, the proposed method can achieve much higher accuracy than all existing method. The purpose of this paper is to verify the accuracy of the synthetic photometry method, together with the accuracy of the data source, so as to determine the availability and advantages of the proposed method. . Experiments show that the proposed method outperforms the-state-of-art stellar instrument magnitudes computation methods, with an improvement of almost 95.8%, which is meaningful for developing high accuracy navigation catalog especially for star trackers with accuracy less than 1". As no assumption is needed, the proposed method can be widely used to compute stellar instrument magnitude for stars of various spectral classes.
    • 06.04 Radar Signal Processing Donnie Smith (Waymo) & Thomas Backes (Thomas D. Backes)
      • 06.0402 Design of Multilayer Airborne Radar Data Processor Narasimhan R S (Center for Airborne Systems, DRDO), Aparna Rathi (Electronics and Radar Development Establishment Bangalore) Presentation: Narasimhan R S - -
        The paper proposes design of multiple-layer robust airborne radar target tracking system. The design also discusses the algorithms that aid in airborne tracking process, different techniques of clutter mitigation at data processor, false tracks suppression and techniques for improvising track maintenance functionality. The objective of the design is to develop a practical, ready to deploy, modular airborne multiple target tracking system. The design is based on layered approach wherein, each layer of tracking system is designed to meet specific function. The proposed approach has three layers with each layer performing a specific function. The first layer is called pre-processing layer with main functionality of clutter mitigation and suppression of unwanted plots. The second layer is targeted to track non-maneuvering targets and detection of target maneuvers. The main functionality of third layer is to track maneuvering targets. The paper also discusses about the interaction between these tracking layers. Some of the salient issues addressed in the paper are suppression of false tracks arising from clutter leaks, ground moving targets, windmills, ghosts and multipath detections. The false tracks could clutter air situation picture and penalize radar resources. The innovation of the paper is in evolving and partitioning of airborne target tracking algorithms into different layers and seamless integration of these layers. The algorithms focus on reduction of false and unwanted tracks in airborne radar, improvement of detection performance through feedback from non maneuver tracking layer and maneuver target tracking layer. The layered design provides advantages in terms of reusability, configurability, maintainability and is scalable and adaptive. The concept of layering facilitates efficient usage of all algorithms. The layered software concept alleviates the burden placed on combat mission commanders since some of the tasks intelligently collate all information along with historical data and hence resolving ambiguous tracks whenever necessary, rejecting the improbable data and adapt automatically to environmental changes.
      • 06.0406 A Time-varying Subcarrier Phase Encoded Radar Waveform Thomas Backes (Thomas D. Backes) Presentation: Thomas Backes - Friday, March 8th, 11:00 AM - Dunraven
        This paper shows the use of varying bandwidth chips in a radar waveform to achieve preferable spectral efficiency and reduced range sidelobes. Example waveforms are shown in comparison to single bandwidth chip waveforms.
    • 06.05 Information Fusion Craig Agate (Toyon Research Corporation) & Stefano Coraluppi (Systems & Technology Research)
      • 06.05 6.05 Keynote:Localisation using signal strength measurements in practice. Fredrik Gustafsson Presentation: Fredrik Gustafsson - - Dunraven
        Radio Signal Strength (RSS) measurements are available for developers in most radio standards, including Bluetooth, WiFi and all cellular systems. Though not being the most informative measurements for localisation purposes, its general availability suggests to always start to look for localization solutions based on RSS, in particular for IoT devices that typically are very simple in their radio interfaces, The presentation will outline a framework for localization with a focus on performance measures and robustness. A number of applications will be presented based on stationary ground sensor networks, mobile agents and drone based as RSS sensors. A particular focus is on search and rescue scenarios where a drone assists the rescue team by looking for opportunistic radio transmitters on the victims.
      • 06.0501 Unifying Multi-Hypothesis and Graph-Based Tracking with Approximate Track Automata Lucas Finn (BAE Systems) Presentation: Lucas Finn - Thursday, March 7th, 05:20 PM - Dunraven
        Multi-target tracking remains a challenging problem, with various approaches addressing different regimes of scenario difficulties. Multi-Hypothesis Tracking (MHT) is often used for short-timescale tracking, while Graph-Based Track stitching (GBT) is often used as a second-stage processor to associate MHT tracks together over time. However, it is often the case that MHT must aggressively prune hypotheses to remain computationally tractable. Moreover, GBT makes strict assumptions about its input, namely Markov or path independence, and is therefore unable to process non-local information such as intermittent attributes on input data. Therefore, both approaches make drastic trade-offs between data association and state estimation: MHT prunes while GBT assumes path independence. We present an approach to the multi-target tracking problem that occupies a “middle” ground between MHT and GBT, reducing to each as a special case. To do this, we represent the current hypothesis set as all those report strings accepted by some automaton: Depending on input statistics (to what extent assignment probabilities are path independent) and on an approximation-fidelity parameter, the automaton will naturally be either an MHT forest, or a min-cost-flow graph, or some intermediate structure. We introduce the formulation, describe algorithms to construct so-called Track Automata, give an Integer Linear Program (ILP) to extract globally optimal tracks from these automata, illustrate key special cases, including where the problem is solvable in polynomial time, and show results for simulated sensor data. In exchange for some user-specified approximation error and polynomial increase in ILP size, the technique is able to delay pruning and improve track purity by implicitly representing many more hypotheses than an MHT forest can.
      • 06.0503 Ground Emitter Localization in the Presence of Multipath Craig Agate (Toyon Research Corporation), Matthew Varble (Toyon), Kenan Ezal (Toyon Research Corporation) Presentation: Craig Agate - Thursday, March 7th, 09:00 PM - Dunraven
        We discuss the problem of ground-based stationary emitter geolocalization in the presence of multi-path in which an emitter’s signal reaches the receiver through reflection from a surface. A particle filtering algorithm is applied to estimate the location of emitting sources in which a source could be the emitter itself or a mirror image of the emitter across a reflective boundary. Each reflective surface creates an ‘image’ of the emitter based on the relative geometry of the reflective surface, the emitter, and the receiver; hence, the receiver will measure the angle-of-arrival (AOA) to each image and possibly to the actual emitter, depending on the geometry. Time difference-of-arrival signals are also processed by the estimation algorithm to further constrain the locations of the images and emitter. We consider only single-bounce reflections of the emitter signal and do not assume that the direct signal is received. The algorithm does not assume any knowledge of the reflective surfaces. The algorithm is evaluated within a simulated environment on a variety of different scenarios. Scenarios include cases in which the direct emitter signal is received (along with reflected signals) and cases in which the direct signal is not received. Additionally, both single and multiple receiver scenarios are considered. Results indicate that the algorithm performs well and handles the large uncertainty in emitter locations early in the estimation, which is challenging when using an estimator based on a single Gaussian representation of the emitter state probability density function.
      • 06.0506 Track-to-track Data Fusion for Unmanned Traffic Management System Krzysztof Cisek (Norwegian University of Science and Technology), Edmund Brekke (Norwegian University of Science and Technology), Mohammed Jahangir (Aveillant Limited), Tor Johansen (Norwegian University of Science and Technology) Presentation: Krzysztof Cisek - Thursday, March 7th, 09:25 PM - Dunraven
        This paper considers data fusion for Unmanned Traffic Management System (UTMS). It presents a track-to-track data fusion system made using multi-target tracking modification of recursive random sample consensus (R-RANSAC) algorithm. The system was developed to work with two independent data sources. The first source of data is cooperative unmanned aerial vehicle (UAV) tracker, the second source is non-cooperative L-Band staring radar, where both trackers main target are UAVs. Tracking data from both sources is delivered to the data fusion system without covariance matrices, which is the reason for using a robust non-deterministic algorithm, such as recursive random sample consensus (R-RANSAC) algorithm. The main goal of the system is to assign tracks from both data sources to a particular target. There are three most likely scenarios with one target: Target has tracks from both sources, track only from non-cooperative radar and track only from the cooperative tracker. Another group are scenarios with multiple targets where their tracks are close to each other, or crossing paths, where each target can have both or just one track from the source. Data from each source have a different rate, latency and noise level, which is also considered in the data fusion. In this paper, we show results of data fusion from simulated and field experimental tests using multi-target tracking modification of recursive random sample consensus (R-RANSAC) algorithm. The experiments conducted in this paper includes experimental tests made at Deenethorpe, UK. Tests were done with the use of cooperative tracker, non-cooperative radar and several small UAVs which were performing flights according to previously planned scenarios. The experimental results show that the presented data fusion method performance has the acceptable level of matching error. The method is considered as a suitable candidate for real-time operation.
      • 06.0507 Tracking Very Low SNR Targets with the Quanta Tracking Algorithm Darin Dunham (Lockheed Martin), Terry Ogle (Georgia Tech Research Institute), Peter Willett (University of Connecticut) Presentation: Darin Dunham - Thursday, March 7th, 09:50 PM - Dunraven
        The Quanta Tracking (QT) algorithm is a fairly new algorithm that is showing very promising results tracking unresolved, dim targets in highly cluttered environments. Traditional detection and tracking approaches use thresholding and signal processing to declare measurements that are then fed into the tracker. The QT algorithm does this all organically in an optimal manner, called, “track-before-detect”. The algorithm requires no thresholding of the data such that all of the data is utilized. The question that always arises is what is the lowest Signal-to-Noise-Ratio (SNR) target that can be tracked by this algorithm? Initial results showed that dim targets down to -15 dB could be tracked reasonably well. Furthermore, it was found that the QT algorithm’s performance against ever dimmer targets decreased gracefully without falling off of “a cliff.” In this paper, we explore a slightly different aspect of low SNR tracking of targets on a focal plane array (FPA). That is, we vary the parameters of the first SNR equation in a different manner that we believe is more controlled.
    • 06.06 Multisensor Fusion William Blair (Georgia Tech Research Institute) & Laura Bateman (Johns Hopkins University/Applied Physics Laboratory)
      • 06.0601 Analytic Emitter Geolocation and Filtering via Time Difference of Arrival Joel Dunham (Georgia Institute of Technology), Jimmy Simmons (Georgia Tech Research Institute), Samuel Shapero (Georgia Tech Research Institute) Presentation: Joel Dunham - Friday, March 8th, 08:30 AM - Dunraven
        Kalman filters have routinely been applied to geolocation problems using Time Difference of Arrival (TDOA) measurements due to the difficulty of obtaining analytic solutions to the hyperbolic isochrons. Extensive testing has been performed with Extended and Unscented Kalman Filters (EKFs and UKFs) for typical TDOA problems, and to a lesser extent Cubature Kalman Filters (CKFs). This paper expands that testing through further simulation to test the limits of the CKFs and UKFs in TDOA applications focusing on Time of Arrival (TOA) measurement noise and reduced dimensions for constraining the problem when a limited number of receivers are available. Analytic solutions to TDOA measurements offer potential performance increases, especially when coupled with Kalman Filters. A recent paper detailing an analytic solution to ellipsoid intersections for multistatic radar is applied to this problem of passive TDOA geolocation of a emitter. This paper develops the analytic solution for passive TDOA geolocation of an emitter and applies this solution through simulations, coupled with a Kalman filter. Limitations of this solution are analyzed, both for dimensionality and robustness with respect to noise in the TOA measurements. Further, performance evaluations for computational time versus accuracy for this technique compared to direct use of Kalman filters on TDOA measurements are detailed. Together, the techniques evaluated in this paper provide data to aid in choosing the appropriate Kalman Filtering method for geolocation through TDOA measurements.
      • 06.0602 Nonlinear Algorithms for Combining Conflicting Information in Multisensor Fusion Jeffery Hurley (Georgia Tech Research Institute), Daniel Johnson (Georgia Tech Research Institute), Joel Dunham (Georgia Institute of Technology), Jimmy Simmons (Georgia Tech Research Institute) Presentation: Jeffery Hurley - Friday, March 8th, 08:55 AM - Dunraven
        One of the most difficult problems in advanced systems today is handling all the identification information that is received from an array of sensors. Dealing with all this information becomes even more of an issue when there is conflicting information. Historically, evidence theory has been used to combine information from different sensors, but handling conflicting information in an intuitive manner continues to be a challenging problem. Often when conflicting information is detected the set of information is processed for outliers in order to remove the conflicting information before fusing the remaining set. This paper describes the use of a nonlinear algorithm in conjunction with the foundations of evidence theory to handle the combination of sensor data in an intuitive manner while also managing conflicting information. The results from a novel nonlinear algorithm is contrasted and compared with results from other modern day evidence theory algorithms.
      • 06.0604 Georectification of Imagery Taken aboard the ISS Utilizing Various Lightning Datasets. Skye Leake (Western Michigan University) Presentation: Skye Leake - Friday, March 8th, 09:20 AM - Dunraven
        The astronauts aboard the International Space Station collect hundreds of images of the Earth below per week. While these images prove to be great photographs of humankind's home they also contain the capacity for some serious scientific discovery. The lack of georectification on these images is hampering the scientific potential contained within. In a small subset of these images the rectification process is being performed. The use of lightning flashes as tie-points to temporally link and subsequently georectify the imagery is performed through a machine vision algorithm. Separation of the lightning flashes from the surrounding surface is crucial for accuracy. The tracked lightning flashes are then matched with other georectified datasets, both optical and ground array based. Video was also tested with success. The higher sampling rate of the video stream (sixty frames per second vs the ~ one from still imagery) provided a means to track the progression of the lightning channel through the cloud in some cases. This allows for exploratory analysis of the multiple scattering effects of the light from the flash diffusing through the cloud. The use of consumer imaging hardware aboard the International Space Station has provided a means to characterize some types of lightning flashes. The larger dataset of theses images collected over the years has the potential to be rich in other observations of various phenomena as well.
      • 06.0605 Don’t Be Greedy, Be Neighborly, a New Assignment Algorithm Bryan O'leary (Northrop Grumman Corporation) Presentation: Bryan O'leary - Friday, March 8th, 09:45 AM - Dunraven
        This paper proposes a new algorithm, the Neighborly algorithm, for solving the assignment problem. The new algorithm achieves much better results than the Greedy algorithm while still running in order N log2 (N). The most efficient algorithm to optimally solve the assignment problem, the JVC algorithm, requires order N^3 operations. However, the Greedy algorithm is still in wide use today by target tracking algorithm practitioners due to its speed. The biggest problem with the Greedy algorithm is that the algorithm makes irrevocable, short sighted, assignments without regard to the global optimal solution. To overcome this weakness the Greedy algorithm is modified by incorporating some of the steps used by the Auction algorithm. To the author’s knowledge, no new sub-optimal algorithms for solving the assignment problem have been proposed in recent years. Simulation results for the Neighborly algorithm compare favorably to optimal algorithms in the sparse target environment, but perform poorly, as expected, in very dense target environments. In both sparse and dense target environments, the Neighborly algorithm outperforms the Greedy algorithm in both computational efficiency and assignment results.
      • 06.0608 Fractional Floodwater-pixel Fusion for Emergency Response Flood Mapping Using SAR Data Young Joo Kwak (ICHARM-UNESCO-PWRI) Presentation: Young Joo Kwak - Friday, March 8th, 10:10 AM - Dunraven
        Emergency hazard and risk mapping services are crucial in providing rapid-response information for disaster management and reducing damage of water-driven cascading disasters such as floods. For rapid-response flood mapping, this study introduces an improved flood detection algorithm to fuse two different C-band and L-band Synthetic Aperture Radar (SAR) images acquired over the same area of interest, e.g., mega-floodplain. The main objective of this study is to propose a new algorithm for dynamic flood detection using two different SAR images acquired at different times and under different conditions. As an image fusion technique, we propose an improved floodwater detection algorithm using the pixel-based water fractional fusion and wavelet-based image fusion. This approach allows investigating the optimization of fusion parameters from two different products in the case of a pre-monsoon flash flood. This preliminary study was conducted to identify and estimate large-scale flood inundation area over a challenging area, where flash flood events often occur along the Maghna River in northen Bangladesh. The resultant fused map of the maximum flood-detect extent suggested the possibility of a rapid and accurate floodwater detection to identify the flood location and extent area with the validation data from ground-truth survey in the representative experiment sites
      • 06.0609 End-to-End Performance Evaluation of Sensor Fusion and Bias Estimation for Multi-Sensor Hand-off Terry Ogle (Georgia Tech Research Institute), William Blair (Georgia Tech Research Institute) Presentation: Terry Ogle - Friday, March 8th, 10:35 AM - Dunraven
        A method for evaluation of the end-to-end performance of a hierarchical sensor fusion system with joint track correlation and fusion and bias estimation is presented along with simulation results that illustrate the method. In a track fusion system, the first level of the fusion system performs joint track correlation and fusion with bias estimation for tracks from a subset of the sensors and those fused tracks are handed off to a second-level for joint track correlation and fusion with bias estimation for tracks from the remaining sensors. The simulated scenario includes two sensors at Level 1 and one sensor at Level 2 for the fusion of a total of three sensors. The joint track correlation, fusion, and bias estimation is achieved with Murty's K-best Hypotheses algorithm. Joint track fusion and bias estimation is performed separately for all of the correlation hypotheses, and the hypotheses are scored and re-ranked to find the best. The established metrics of pattern accuracy, pattern consistency, pattern containment, and the probability of correct correlation are used to characterize performance versus track density. A joint track and bias containment metric over a cluster of tracks, pattern complex containment, is developed and proposed for assessing the end-to-end performance after hand-over to the sensors at Level 2. Monte Carlo simulations were performed to demonstrate and compare the pattern metrics and probability of correct correlation after hand-over for various aspect angles between sensors, various number of targets in the pattern, and various levels of sensor bias. The results show that the pattern complex containment metric matches the chi square threshold probabilities when track-to-track correlation is near perfect, and therefore, it should be a good indicator of successful sensor hand-over performance.
    • 06.07 Applications of Target Tracking John Glass (Raytheon Company) & Yaakov Barshalom (University of Connecticut)
      • 06.0701 Informative Path Planning for Active Tracking of Agile Targets Per Boström Rost (Linköping University), Daniel Axehill (Linköping University), Gustaf Hendeby (Linköping University) Presentation: Per Boström Rost - Wednesday, March 6th, 08:30 AM - Dunraven
        This paper proposes a method to generate informative trajectories for a mobile sensor that tracks agile targets. The sensor is assumed to have limited field of view and sensing range, and to be capable of obtaining noisy measurements of a target's position. The goal is to generate a sensor trajectory that maximizes the tracking performance, captured by a measure of the covariance matrix of the target state estimate. Since the targets maneuver, it is necessary to re-plan the sensor trajectory online when new measurements are obtained. This is done in a receding horizon fashion. The active target tracking problem hence is a combination of estimation and control, which is often referred to as informative path planning (IPP). When using sensors with limited field of view, the tracking performance depends on the actual measurements obtained as well as the trajectory of the target. This is a complicating factor for IPP, as the objective function of the optimization problem hence depends on future measurements and the true target trajectory, both which are naturally unavailable in the planning stage. Due to this uncertainty, the planning problem solved in each iteration of the receding horizon control loop becomes a stochastic optimization problem, where the expectation is taken with respect to the measurement noise and the target state. This paper proposes a method to solve the stochastic planning problem using an approximation based on deterministic sampling of the predicted target distribution. An extended Kalman filter (EKF) is used to estimate the state of the target and by sampling the predicted target distribution, a number of plausible trajectories are obtained. These candidate target trajectories are then used to approximate the expectation with respect to the target state. This is in contrast to prior work, where only the most likely target trajectory is considered. The proposed method is evaluated using Monte Carlo simulations of different relevant tracking scenarios. A conventional IPP method is used as baseline. It is shown how the proposed method significantly improves the ability to track agile targets, with retained tracking accuracy, compared to the baseline method.
      • 06.0705 Survey of Challenges in Labeled Random Finite Set Distributed Multi-sensor Multi-object Tracking Augustus Buonviri (Sandia National Laboratories), Matthew York (Sandia National Laboratories), Keith Le Grand (Sandia National Laboratories), James Meub (Sandia National Laboratories) Presentation: Augustus Buonviri - Wednesday, March 6th, 08:55 AM - Dunraven
        Distributed multi-sensor multitarget tracking (MS-MTT) has potential applications in a number complex modern problems including space debris tracking, air traffic control, surveillance, and traffic monitoring. Labelled Random Finite Set (LRFS) filtering is a relatively new and attractive MTT technique that has potential for addressing this problem. Specifically, the mathematics of finite set statistics (FISST) enables the principled fusion of LRFS densities, which promises better distributed tracking performance compared to other techniques. However, current methods for performing fusion of LRFS densities have a number of assumptions, limitations, and drawbacks that prevent applying them to any but the simplest distributed MS-MTT scenarios. For example, the geometric mean density (aka generalized covariance intersection) approach assumes consistency of target labels accross all densities, which is impossible to achieve in practice. An overview and characterization of this and other challenges affecting the fusion of LRFS densities for distributed MS-MTT is presented.
      • 06.0707 Time-lapse Imaging for Studying Atmospheric Refraction: Measurements with Natural Targets Wardeh Al Younis (), Christina Nevarez (), David Voelz (New Mexico State University) Presentation: Wardeh Al Younis - Wednesday, March 6th, 09:20 AM - Dunraven
        In this paper, we discuss developments in using natural targets (terrain and vegetation features) for refractive studies. Natural targets provide for the opportunity to study refraction in rural settings. One camera system was deployed at a remote location in the White Sands Missile Range in New Mexico, and was pointed at a natural desert landscape focusing on a mountain range. Day and night images from this system were collected from January 2018 to February 2018. A second camera system is currently stationed in the desert of the Jornada Experimental Range in New Mexico, focusing on a mountain range and desert valley. This system was set up in May 2018 with a planned operation of one year. We describe a point tracking image processing approach and present refraction analyses of the images from the time lapse systems. We discuss corrections for camera motion and correlations with meteorological data.
      • 06.0710 Note on Sensor Resource Allocations: Higher Rate or Better Measurements? Yan Wang (Georgia Institute of Technologies), William Blair (Georgia Tech Research Institute) Presentation: Yan Wang - Wednesday, March 6th, 09:45 AM - Dunraven
        When the need to improve the tracking arises, one is often faced with the choice of increasing the measurement accuracy or rate.The answer to this question is found by assessing the impact on error in the filtered state estimates and the one-step predicted state estimates. In this paper, the tracking of maneuvering targets with a nearly constant velocity (NCV) Kalman filter is considered and the maximum mean squared error (MMSE) is utilized to study the impacts of doubling the measurement accuracy or rate. For each measurement case and the maximum acceleration of the maneuvering target, the process noise variances that minimize the MMSE in the filtered position and the one-step predicted position are used to assess the impacts of doubling the measurement accuracy or rate. The analysis shows that doubling the measurement accuracy gives the greater reduction in MMSE in filtered position, while doubling the measurement rate gives the greater reduction in the MMSE in the one-step predicted position. Selection of the process noise variance that minimizes the MMSE in the one-step predicted position estimates is also new in this paper. Monte Carlo simulation results are given for tracking a maneuvering target with an NCV Kalman filter to verify the findings and an Interacting Multiple Model (IMM) estimator tracking a maneuvering target to assess the generally applicability of the findings.
    • 06.08 Guidance, Navigation and Control Christopher Elliott (Lockheed Martin Aeronautics Company and University of Texas at Arlington) & Terry Ogle (Georgia Tech Research Institute)
      • 06.0803 In-Flight Adaptive PID Sliding Mode Position and Attitude Controller Hailee Hettrick (Massachusetts Institute of Technology), Jessica Todd (Massachusetts Institute of Technology) Presentation: Hailee Hettrick - Wednesday, March 6th, 10:10 AM - Dunraven
        Future spacecraft operations, such as debris capture and autonomous in-orbit servicing, will require spacecraft to interact with objects with poorly defined inertial properties which introduce a large degree of uncertainty into the dynamics of such operations. To handle this uncertainty, this paper describes the development and validation of a mass property-resilient controller for position and attitude control of a free-flying spacecraft. Specifically, the proportional-integral-derivative (PID) sliding mode controller (SMC) was developed to account for inaccurate knowledge of mass properties of small spacecraft, using sliding mode variables for each axis and an adaptive determination of the appropriate integral and derivative gains to achieve a commanded motion. The controller was validated both in simulation and in ground-based tests on the SPHERES (Synchronized Position Hold Engage Reorient Experimental Satellites) platform, small free-floating autonomous satellites used to study precision navigation and maneuvering. The SPHERES was commanded to follow a specified series of maneuvers using the PID SMC, to assess the convergence time of the sliding variables, gain values and commanded state parameters in each maneuver. The PID SMC performed well in simulation, with the sliding variables associated with position converging to the desired zero value within the span of one maneuver, while the attitude controller exhibited some chattering. In hardware tests, the position sliding variables exhibited slight chatter, consistent with slow convergence to the desired zero value, whereas the attitude sliding variables had significant chattering. The same tests were run using a static PID controller designed with inaccurate mass property knowledge, and the results were compared to those of the PID SMC. From this comparison, it is evident that the PID SMC offers superior performance under mass property uncertainy. Future work will attempt to address the PID SMC’s chattering issues with the introduction of a boundary layer in the attitude sliding variable.
      • 06.0807 Distributed Localization and Control of Quadrotor UAVs Using Ultra-Wideband Sensors Jing Wang (Bradley University) Presentation: Jing Wang - Tuesday, March 5th, 10:35 AM - Lake/Canyon
        In this paper, we propose a distributed control algorithm for Quadrotor UAVs. The main objective is to design practically implementable distributed hierarchical control for coordinated formation flying of UAVs. Based on the use of Ultra-Wideband sensors for localization, the experimental results using a number of nano Crazyflie quadrotors are also reported in the paper by implementing a simplified hierarchical control strategy. The experimental system setup and the basic formation flying control results using Ultra-Wideband sensors pave the way for the full implementation of the proposed distributed hierarchical control algorithms in the future work. The Crazyflie 2.0 quadrotor UAVs produced by Bitcraze are adopted in experiments. The conducted research provides a useful design guideline for applications of UAVs swarms in real situations.
      • 06.0808 Three-dimensional Impact Angle Guidance Laws for Precision Guided Munition Daniel Lee (), Han Lim Choi () Presentation: Daniel Lee - Wednesday, March 6th, 11:25 AM - Dunraven
        This paper proposes three-dimensional guidance laws for impact efficiency enhancement of precision guided munitions. This requires a vertical impact angle while the maneuverability and overall flight time of a munition are limited. For that, nonsingular terminal sliding mode control theory is applied which uses two switching surfaces of power-rate reaching law. The proposed guidance law allows a projectile a trajectory with desired terminal impact angle in a finite time with allowable control inputs while handling the coupled non-linear dynamical behavior of munitions. Furthermore, it prevents the singularity problem of the conventional terminal sliding mode controller. To verify the performance of the proposed guidance law against a stationary target, it has been applied on a realistic ballistic model which considers drag and gravity effects. Simulations results demonstrates the performance and the limit under various launch conditions are investigated.
      • 06.0810 Overhead Detection, Identification, and Tracking of Multiple Surface-based Exploration Vehicles Wolfgang Fink (University of Arizona), Qasim Mahmood (University of Arizona) Presentation: Wolfgang Fink - Wednesday, March 6th, 11:00 AM - Dunraven
        As NASA and other space agencies venture out to explore planetary bodies of high interest (Mars, Titan, Europa, Enceladus, etc.), especially from an astrobiological point of view, i.e., the quest for extant/extinct life beyond Earth, planetary field geologists will have to be replaced and emulated by robotic spacecraft, at least for the foreseeable future. As such, these robotic explorers will have to be equipped with observation, analysis, and reasoning capabilities of a field geologist. Moreover, to mimic the geologic approach of local to regional to global reconnaissance in an integrated, mutually informing fashion, these robotic explorers will likely have to operate as part of multi-tiered robotic mission architectures. Several precursors to such mission architectures have been proposed, such as the introduction of an overhead perspective either through a balloon, blimp, airship, or helicopter/rotorcraft. Using an overhead perspective provides many advantages for exploration and reconnaissance, as well as for guidance, navigation, and control (GNC). A real-world instantiation of an overhead perspective is the use of the HiRISE camera aboard Mars Reconnaissance Orbiter for GNC support of the Mars Exploration Rovers. In this context, this paper focuses in particular on the challenge of detection, identification, and tracking of multiple deployed ground-agents, such as rovers on Mars or lake landers on Titan. The devised framework comprises the use of distinct, highly rotation, transformation, and scaling variant templates that are matched to similar markings on top of the respective deployed ground-agents through rotation, transformation, and scaling operations. This allows the spatial detection and identification of the respective ground-agents. The centroids of the detected templates are subsequently tracked simultaneously through the repeated use of this template-matching procedure. This detection, identification, and tracking framework enables the GNC of multiple, and thus expendable, ground-agents from an overhead perspective(s), e.g., as part of multi-tiered exploration mission architectures to access high(er)-risk, but high(er) science payoff regions.
    • 06.09 Fusion Integration of Sensor Harvesting Erik Blasch () & Peter Zulch (Air Force Research Laboratory)
      • 06.0901 Taking Advantage of Group Behavior When Tracking Multiple Threats in Cluttered Surveillance Data Peter Willett (University of Connecticut), Andrew Finelli (University of Connecticut), Yaakov Barshalom (University of Connecticut) Presentation: Peter Willett - Wednesday, March 6th, 04:30 PM - Cheyenne
        Threats are composed of some process or plan being carried out by a group of people with an end goal that is generally to cause harm. Some examples of these kinds of threats are terrorist attacks, military actions, or stock fraud. These threats can be modeled stochastically with help from experts within the relevant field. We model these threats with a hypothesis as to how these events will unfold along with a method for observing the unfolding threat. We will use this model to detect the threat before its completion and, ideally, allow for preemptive action against it. The models used for threats in this paper are variations of Hidden Markov Models (HMMs) with sparse observation emission (rare as compared to the expected process length). The population observed is assumed to be organized into groups called "cliques". Rather than tracking an individual's involvement probability as was done in a related effort, we track a clique's (group's) involvement probability across all threats using a Bayesian update equation and conditioning on association events between the observations and the set of measurement generating HMMs (threat and clutter processes). We assign an individual's involvement probability conditionally based on that of their group, and thence the state of each threat process then its state is estimated using a bank of Bernoulli filters. This will allow us to accurately detect multiple threat processes within a single stream of observations (most of which will be clutter).
      • 06.0902 Joint-Sparse Decentralized Heterogeneous Data Fusion for Target Estimation Ruixin Niu (Virginia Commonwealth University), Peter Zulch (Air Force Research Laboratory), Marcello Di Stasio (AFRL), Genshe Chen (Intelligent Fusion Technology, Inc), Dan Shen (Intelligent Fusion Technology, Inc), Zhonghai Wang (IFT), Jingyang Lu (International fusion technology) Presentation: Ruixin Niu - Wednesday, March 6th, 04:55 PM - Cheyenne
        In our recent work, we developed a new joint-sparse data-level fusion (JSDLF) approach to integrate heterogeneous sensor data for target discovery. In the approach, the target state space is discretized and data fusion is formulated as a joint sparse signal reconstruction problem, which is solved by using simultaneous orthogonal matching pursuit (SOMP). In our previous work, the joint sparse signal recovery approach has been implemented in a centralized manner. Namely, all the raw sensor data are transmitted to a fusion center, where they are fused to detect and estimate the targets. The drawback of the centralized network is its high communication cost and its lack of robustness, since the global information is stored and processed at a single point, the fusion center. In this paper, several decentralized JSDLF approaches have been developed, that provide exactly the same estimation result at each sensor node as the centralized algorithm does. Further, two distributed database query algorithms, Threshold Algorithm (TA) and Three-Phase Uniform Threshold (TPUT) have been combined with the SOMP algorithm to reduce communication costs. Numerical examples are provided to demonstrate that the proposed decentralized JSDLF approaches obtain excellent performance with accurate target position and velocity estimates to support situational awareness, while at the same time achieving dramatic communication savings.
      • 06.0903 Joint Manifold Learning Based Distributed Sensor Fusion of Image and Radio-Frequency Data Dan Shen (Intelligent Fusion Technology, Inc), Jingyang Lu (International fusion technology), Peter Zulch (Air Force Research Laboratory), Marcello Di Stasio (AFRL), Genshe Chen (Intelligent Fusion Technology, Inc), Zhonghai Wang (IFT), Ruixin Niu (Virginia Commonwealth University) Presentation: Genshe Chen - Wednesday, March 6th, 05:20 PM - Cheyenne
        In many site-monitoring scenarios using multi-sensor modalities, the data streams not only have a high dimensionality, but also belong to different phenomena. For example, a moving vehicle may have an emitter that transmits radio-frequency (RF) signals, its exhaust system sends acoustic signals, and its perspective observed which may be collected by passive radars, acoustic sensors, and video cameras; respectively. These cases demonstrate that a target (the moving object) observed by three different modalities (data streams collected by acoustic sensors, passive radars, and cameras) could benefit from sensor fusion to increase the tracking accuracy. This paper presents a joint manifold learning based distributed sensor fusion approach for image and radio frequency (RF) data. A typical scenario includes several objects (with RF emitters), which are observed by a network of platforms with Medium Wavelength Infrared (MWIR) cameras and/or RF Doppler sensors. Based on a joint manifold learning (JML) sensor fusion approach, we propose to design and implement a distributed heterogeneous data fusion approach for improved Detection, Classification, and Identification (DCI) of targets and entities in dynamic environments with constrained communications. We design and implement distributed JML using diffusion and consensus approaches. In our distributed mechanism, we first partition the JML matrices into submatrices for each platform. For every platform, these submatrices represent the mapping from the sensor data to its contribution in the final fused result. Each node processes the local measurements using submatrices and shares the results with a limited number of neighbors. A prototype is constructed that includes drones, onboard processing capabilities (Intel NUC), cameras, and radars to demonstrate the proposed distributed data fusion approach. To explore the system robustness, supportive results are achieved from simulated radio-frequency interference (RFI) and imperfect communication links.
      • 06.0904 Multi-scale Geometric Summaries for Similarity-based Sensor Fusion Christopher Tralie (Duke University), Paul Bendich (Geometric Data Analytics, Inc.), John Harer (Duke University) Presentation: Christopher Tralie - Wednesday, March 6th, 09:00 PM - Cheyenne
        In this work, we address fusion of heterogeneous sensor data using wavelet-based summaries of fused self-similarity information from each sensor. The technique we develop is quite general, does not require domain specific knowledge or physical models, and requires no training. Nonetheless, it can perform surprisingly well at the general task of differentiating classes of time-ordered behavior sequences which are sensed by more than one modality. As a demonstration of our capabilities in the audio to video context, we focus on the differentiation of speech sequences. Data from two or more modalities first are represented using self-similarity matrices (SSMs) corresponding to time-ordered point clouds in feature spaces of each of these data sources; we note that these feature spaces can be of entirely different scale and dimensionality. A fused similarity template is then derived from the modality-specific SSMs using a technique called similarity network fusion (SNF). We investigate pipelines using SNF as both an upstream (feature-level) and a downstream (ranking-level) fusion technique. Multiscale geometric features of this template are then extracted using a recently-developed nonlinear alternative to wavelets called the scattering transform, and these features are then used to differentiate speech sequences. This method outperforms unsupervised techniques which operate directly on the raw data, and it also outperforms stovepiped methods which operate on SSMs separately derived from the distinct modalities. The benefits of this method become even more apparent as the simulated peak signal to noise ratio decreases.
      • 06.0905 Multimodal Fusion Using Deep Directional Unit Networks for Event Behavior Characterization Denis Garagic (BAE Systems), Fang Liu (BAE Systems, Inc.), Peter Zulch (Air Force Research Laboratory), Brad Rhodes () Presentation: Denis Garagic - Wednesday, March 6th, 09:25 PM - Cheyenne
        The increasing availability of many sensing modalities (imagery, radar, radio frequency (RF) signals, acoustical, and seismic data) reporting on the same phenomena introduces new data exploitation opportunities. This also creates a need for fusing multiple modalities in order to take advantage of inter-modal dependencies and phenomenology, since it is rare that a single modality provides complete knowledge of the phenomena of interest. In turn, this raise challenges beyond those related to exploiting each modality separately. Traditional approaches centered on a cascade of signal processing tasks to detect elements of interest (EOIs) within locations/regions of interest (ROIs), followed by temporal tracking and supervised classification of these EOIs over a sequence of observations, is not able to optimally exploit inter-modal characteristics (e.g., spatio-temporal features that co-vary across modalities) of EOI signatures. This paper presents an end-to-end spatiotemporal processing pipeline that uses a novel application of dynamic deep generative neural networks for fusing ‘raw’ and / or feature-level multi-modal and multi-sensor data. This pipeline exploits the learned joint features to perform detection, tracking, and classification of multiple EOI event signatures. Our deep generative learning framework is composed of Conditional Multimodal Deep Networks that extend deep generative network models to enable a general equivariance learning framework with vector-valued visible and hidden units called directional units (DUs). These DUs explicitly represent sensing state (sensing / not sensing) for each modality and environmental context measurements. Direction within a DU indicates whether a feature (within the feature space) is present and the magnitude measures how strongly that feature is present. In this manner, DUs concisely represent a space of features. Furthermore, we introduce a dynamic temporal component to encoding the visible and hidden layers. This component facilitates spatiotemporal multimodal learning tasks including multimodal fusion, cross-modality learning, and shared representation learning, as well as detection, tracking, and classification of multiple known and unknown EOI classes in an unsupervised and/or semi-supervised way. This approach overcomes the inadequacy of pre-defined features as a means for creating efficient, discriminating, low-dimensional representations from high-dimensional multi-modality sensor data collected under difficult, dynamic sensing conditions. This paper presents results that demonstrate our approach enables accurate, real-time target detection, tracking, and recognition of known and unknown moving or stationary targets or events and their activities evolving over space and time.
      • 06.0906 ESCAPE Data Collection for Multi-Modal Data Fusion Research Peter Zulch (Air Force Research Laboratory), Erik Blasch () Presentation: Peter Zulch - Wednesday, March 6th, 09:50 PM - Cheyenne
        This presentation details a recent 2018 multi-modal data collection performed by the Air Force Research Laboratory (AFRL), Information Directorate. This data collection satisfies the multi-source fusion communities desire to have a data set available for data fusion research and algorithm development. The data collection utilizes six modalities (Electro Optical, Infrared, Passive Radio Frequency Receive, Radar, Seismic, and Acoustic) collecting simultaneously. The observed scenes contained moving, emitting, multi-vehicle scenes driving in orchestrated paths. There were over 20 sensors, covering the 6 modalities, observing the scene simultaneously. A large building (acting as a tunnel) and a tree line added realism and obscuration at times during each collection run. Approximately 90 data collection runs were recorded, each approximately one minute in duration. AFRL is currently working on public release of some of the data sets for use by the research community.
  • 7 Avionics and Electronics for Space Applications Harald Schone (Jet Propulsion Laboratory) & John Samson (Morehead State University / Aerospace Technologies Plus) & John Dickinson (Sandia National Laboratories)
    • 07.01 High Performance Computing, Data Processing, and Interconnects for Space Applications Jamal Haque (Honeywell) & Joseph Marshall (BAE Systems)
      • 07.0101 High Performance Computing for Precision Landing and Hazard Avoidance and Co-design Approach David Rutishauser (NASA - Johnson Space Center) Presentation: David Rutishauser - Monday, March 4th, 04:30 PM - Lake/Canyon
        The Safe and Precise Landing Integrated Capabilities Evolution (SPLICE) project continues NASA’s technology development for Precision Landing and Hazard Avoidance (PL&HA). The High-Performance Space Computing (HPSC) project manages a contract to build a multi core processor that is intended to be NASA’s computing platform for future human and robotic spaceflight missions. This paper describes the flight computer for the PL&HA payload that will be used in SPLICE flight testing onboard suborbital rockets. This computer is being designed as a surrogate architecture for the HPSC chip, using a Xilinx Multi-Processor System on a Chip (MPSoC). Early design trades for the SPLICE surrogate implementation are described. Preliminary performance testing on the surrogate platform using an optical navigation algorithm developed for the Orion vehicle is described, and shows 2.5 times execution speedup resulting from minimal modifications to the original code. In general, High Performance Computing/Embedded Computing (HPC/HPEC) required to address computational challenges in a wide range of NASA missions has consistently had challenges in implementation due to the diversity in the disciplines required to develop a solution. Typically, algorithm designers with expertise in the physics of the problem, and numeric approaches to solving the relations that model the physics, do not have expertise in processing architectures. There are strong dependencies between the overall performance of the system and the choices made in the modeling of the physics, the numerical approaches to solutions for the physical relations, and how these operations are mapped to computational resources in an architecture. To address this concern, a Model-Based Systems Engineering (MBSE) based concept for conducting multi-disciplinary co-design of the Guidance, Navigation, and Control (GN&C) algorithms, processing hardware configuration, and system software is introduced.
      • 07.0102 Emulation-based Performance Studies on the HPSC Space Processor Benjamin Schwaller (University of Pittsburgh) Presentation: Benjamin Schwaller - Monday, March 4th, 04:55 PM - Lake/Canyon
        In this research, we develop and employ hardware testbeds to emulate and predict performance of the High-Performance Spaceflight Computing (HPSC) processor. This new processor, sponsored by AFRL and NASA, is being developed by Boeing for future space missions. This processor will be based on a "chiplet" design where each chiplet features two quad-core ARM Cortex-A53 CPUs connected by an AMBA.These chiplets can be connected by different serial interfaces which provides a flexible platform to serve a variety of potential mission needs. Using kernel and Ethernet performance results from two testbeds, we create a model to project the performance of the HPSC processor across a suite of space-related benchmarks. We project that synthetic aperture radar (SAR), the most compute-intensive application in the suite, will scale well on a multi-chiplet platform. Smaller kernels, such as matrix addition, suffer from significant parallelization overhead across multiple chiplets and even across AMBA on a single chiplet. Overall, the work presented in this paper forecasts and evaluates the benchmarking performance of the HPSC processor for a variety of space-related kernels and reveals techniques to optimize apps for this system.
      • 07.0103 Volatile Register Handling for FPGA Verification Based on SVAs Incorporated into UVM Environments Kai Borchers (German Aerospace Center - DLR), Sergio Montenegro (University Würzburg), Frank Dannemann (German Aerospace Center - DLR) Presentation: Kai Borchers - Sunday, March 3th, 09:25 PM - Jefferson
        Verification of Field Programmable Gate Array (FPGA) designs is a challenging task which can be managed in different ways. By now, Universal Verification Methodology (UVM) is the de-facto standard for functional verification of Register Transfer Level (RTL) designs throughout all industry branches. Among others, UVM proposes to check for correct Device Under Test (DUT) behavior in an automated way, based on observing applied stimulus used to predict the expected DUT reaction. However, the prediction requires a DUT model whereas some DUT properties are complicated or even impossible to predict. Volatile registers are an example for this kind of problem. This paper introduces a way to incorporate volatile register comparisons inside the UVM environment alongside standard registers. This is done by utilizing SystemVerilog Assertions (SVA) which observe volatile registers to provide their values to the UVM environment directly at the time they are accessed.
      • 07.0104 11b/14b Encoding - a Fault Tolerant, DC-Balanced Line Code for AC-Coupled Channel Link Transceivers Jeffrey Boye (JHUAPL), Adam Mizes (Johns Hopkins University/Applied Physics Laboratory), Laurel Funk (JHU) Presentation: Jeffrey Boye - Sunday, March 3th, 04:55 PM - Jefferson
        Brief powerpoint summary of the development of the 11b14b code and current work / updates from most recent lab results.
      • 07.0105 Comparative Benchmarking Analysis of Next-Generation Space Processors Evan Gretok (NSF SHREC Center - University of Pittsburgh), Alan George (University of Pittsburgh), Evan Kain (University of Pittsburgh) Presentation: Evan Gretok - Monday, March 4th, 09:25 PM - Lake/Canyon
        This research examines the performance of two next-generation space processors, the BAE Systems RAD5545TM processor and the NASA High-Performance Spaceflight Computing (HPSC) processor, by comparative application benchmarking. These devices, among the first radiation-hardened multi-core architectures for space, can attain significant performance via parallel processing. These performance gains enable performance not previously attainable in space and application domains once deemed infeasible for space, such as high-resolution image processing and machine learning. This presentation will begin by detailing background on space radiation effects and the need for radiation-hardened processors. Important points on shared-memory multiprocessing used in achieving parallelism with OpenMP on multicore processors will also be summarized. Next, the presentation will cover details and specifications of the space-grade processing platforms focused on and, due to their continued development, the hardware facsimile devices chosen to represent them in this study. Brief background and relevant use cases for each application employed in this research will also be noted. Results from the analysis of these facsimile platforms, consisting of execution times, speedups, parallel efficiencies, and energy consumptions for each application on each tested device, will be abbreviated. The methodology utilized to forecast the performance of the radiation-hardened devices from the facsimile results via a combination of underclocking and frequency scaling will be detailed. Particular points of comparison indicating strengths and weaknesses of each architecture will be discussed. Finally, overall conclusions drawn on the key capabilities of each platform will be shared. Presentation of this research will depict a thorough representation of how these next-generation space processors will compare and compete to meet the growing need for high-performance on-board processing capabilities in the latest spacecraft and missions.
      • 07.0108 The Development of Standard Controller for Chinese Space Science Experiments Wenbo Dong (Chinese Academy of Sciences) Presentation: Wenbo Dong - Sunday, March 3th, 04:30 PM - Jefferson
        The orbital environment provides a unique opportunity for microgravity science experiments. Scientific satellites, on-orbit science laboratories, and space stations carry a number of experiment payloads, in disciplines such as life science, material science, fluid mechanics, combustion and fundamental physics. Most of those scientific payloads need automatic operation and control. The automatic function includes the detection of various physics quantity, the drive of various movement mechanism, automatic information transmission and power management. Generally, the payload control system is some complex and diverse, therefore the development cycle may be very long and often postpone the launch of the scientific experiment and delay the important scientific discovery. By decades of experience on payload development, we focus on the standard computer special for payload control. Here a high-reliability computer conformed with open-VPX standard is developed. The computer includes a flexible high-strength structure with arbitrary number of slots which could plug into circuitry boards, such as central control board, power module board, A/D conversion board, interface board and so on. As examples, we introduce three projects using our standard computers, including the controller of the science experiment data handling unit (SEHU) on Tianzhou-1, the controller of evaporation condensation experiment on Tianzhou-1, the controller of microgravity vibration active isolation system (MAIS) on Tianzhou-1, and the controller on a boiling bubble experiment and a material transportation experiment on Practical Satellite 10, as well as some undergoing projects on Chinese Space Laboratory. The control requirements of these experiments are listed and the framework design of the controller and its electronic system is introduced. All products of those controllers are developed rapidly, and have been verified on orbit environment or by ground test. It is a good progress for scientists to realize their idea from imagine to practice. In the future, we expect standard controllers could support more kinds of microgravity experiments and benefit the space utilization.
      • 07.0110 High Performance Computing Applications in Space with DM Technology Aaron Zucherman (Morehead State University), Benjamin Malphrus (Morehead State University), John Samson (Morehead State University / Aerospace Technologies Plus) Presentation: Aaron Zucherman - Monday, March 4th, 05:20 PM - Lake/Canyon
        Dependable Multiprocessor or DM technology was developed as way of enabling high-performance Commercial-Off-The-Shelf (COTS) processing systems to effectively operate in a space environment. DM technology is an architecture and software framework that enables the latest COTS processing systems to operate in inhospitable environments by providing software-based fault-tolerance. A DM system is a scalable cluster of processors with a high-speed interconnect with an application and hardware independent middleware. The objective of the DM7 flight experiment was to build, test, and demonstrate DM technology in a space environment. DM7 was launched to the ISS in December 2016. The experiment was activated in April 2017 running on-orbit checkouts, experiments, and capturing and compressing camera images. DM operation was successfully demonstrated on-orbit, reaching TRL-7. DM is a pervasive technology applicable to almost any application where high-performance rad-tolerant or fault-tolerant computing is required. Numerous applications have been developed and demonstrated on a variety of DM platforms. Potential applications include: intelligent data mining and data compression, autonomous navigation, autonomous operation & control, advanced space-based networked communication, sophisticated earth observation, astrophysics, and ground-commanded programmable image compression amongst others. The demonstrated applications show the breadth, flexibility, scalability, ease of use, low overhead, and processing potential of DM technology.
      • 07.0112 Performance Analysis of Standalone and In-FPGA LEON3 Processors for Use in Deep Space Missions Dmitriy Bekker (Johns Hopkins Applied Physics Laboratory), Minh Quan Tran (JHUAPL) Presentation: Dmitriy Bekker - Monday, March 4th, 09:00 PM - Lake/Canyon
        When considering a new processor for a mission, one of the first questions that comes up is: "How does this processor compare with what we have used in the past?" Manufacturers use benchmarks to compare normalized performance from one product to another, but often these data are incomplete and are missing key parameters such as compiler version, compile options used, memory type, and many others. In this work, we present carefully documented benchmarking results for single-core and multi-core Gaisler LEON3 processors. We evaluate both standalone (UT699, UT700, GR712RC-multi-core) and in-FPGA soft-core (single-core LEON3, quad-core LEON3) processors. In the case of multi-core processors, we use the OpenMP API with RTEMS-5.0 real-time operating system to demonstrate performance gains with automatic parallelization of computationally intensive code segments. With increasing demand for high-performance FPGAs on space missions, the option to drop in a soft-core processor into the system design should be on the table, provided there are available FPGA resources. We show that the soft-core LEON3 implementation has comparable frequency-normalized performance and is a good alternative or supplement to a dedicated standalone hard-core processor. By adding one or more soft-core processors into the FPGA design, the data systems architect may eliminate additional hardware, save on overall power, and improve net system performance by optimizing HW-to-SW data transfers. On-board processing, communications, and data management tasks can benefit from a tightly coupled processor inside an FPGA. We present various architectural design considerations that impact the performance and resource utilization of LEON3 processors inside a Microsemi RTG4 FPGA.
      • 07.0113 Improving a Successful Space Electronics High Performance Fabric-Based Standard Joseph Marshall (BAE Systems), Patrick Collier (AFRL), Clifford Kimmery () Presentation: Joseph Marshall - Sunday, March 3th, 09:00 PM - Jefferson
        As this current decade dawned, space electronics faced an oncoming change in its architecture in order to provide more onboard processing and data bandwidth connectivity. Bus structures such as 1553 and CompactPCI had reached their capacities. Several private, public and institutional organizations began looking forward toward systems that would be connected by various interconnect fabrics instead of busses. In 2011, the Next Generation Space Interconnect Standards (NGSIS) group was formed to attempt to standardize the new interconnection technology and avoid the more expensive prior method of point solutions. The group began pooling information, examining use cases for future processing and choosing the standards necessary to advance this goal. One of these was SpaceVPX™, a space version of the popular OpenVPX standards. The group started work on SpaceVPX in early 2012 and in 2015, the SpaceVPX System standard ANSI/VITA 78.00 was released as the result. Since then, SpaceVPX has seen increased use and interest in the onboard space electronics arena. An errata list was published in 2016, picking up a small set of obvious mistakes in the greater than 400-page standard. The organization of the original 2015 standard document closely followed the OpenVPX standards while inserting several new sections defining features needed by a single-fault-tolerant space electronics solution. The 2015 document presented difficulties in finding all the material needed to understand and create SpaceVPX standard-compliant products. Because of the document organizational and clarity issues, the VITA 78 working group has been holding weekly telecons since 2016 toward the completion of a more user-friendly revision of the standard. Among its improvements are to update the SpaceVPX standard to correct errata and editorial errors, to reorganize the Space Utility Management sections to better match other OpenVPX standards and to fix inconsistencies within the standard. Additionally, mechanical drawings for 3U modules and for 1.6" pitch modules were added. A more overhead-efficient 3U SpaceUM module has also been defined. SpaceFibre has been added as an alternate data or control plane. Control plane access to the Direct Access Protocol Registers has been added for systems not using the utility plane fabric. RF and Optical options are being added to the module profiles building on changes in OpenVPX. Slot and module profiles are being added and simplified. The revision began balloting toward standard approval in the fourth quarter of 2018. This paper reviews the history and capabilities of the released SpaceVPX standard and describes the updated sections, improvements and changes in process. Use cases illustrate potential advantages of the changes and range of potential new usage. Potential follow-on standards to this revision are also described.
      • 07.0114 SpaceFibre Interfaces and Architectures Steve Parkes (University of Dundee), Alberto Gonzalez Villafranca (STAR-Dundee Ltd) Presentation: Steve Parkes - Sunday, March 3th, 05:20 PM - Jefferson
        SpaceFibre is the next generation of SpaceWire network technology for spacecraft on-board data-handling. It runs over electrical or fibre-optic cables, operates at very high data rates, and provides in-built quality of service (QoS) and fault detection, isolation and recovery (FDIR) capabilities, providing high-reliability and high-availability. The presentation first gives an introduction to SpaceFibre and then describes how SpaceFibre can be used as an instrument interface, as the interface and memory interconnection network in a mass-memory unit, as the interface to a downlink transmitter and as the backplane for a payload processing unit. An overall payload processing architecture based on SpaceFibre is also presented and the way in which existing SpaceWire equipment can be readily integrated into a SpaceFibre network is explained.
      • 07.0116 UVM Based Verification for HPSBC-FPGA of the Dream Chaser's Fault Tolerant Flight Computer Khurram Kazi (Draper) Presentation: Jonathan Frey - Sunday, March 3th, 09:50 PM - Jefferson
        Sierra Nevada Corporation’s flagship Dream Chaser spacecraft will use a Fault Tolerant Flight Computer (FTFC) for its missions to the International Space Station. One of the integral components of the FTFC is a Field Programmable Gate Array (FPGA) that assists with the control of mission critical functions of the flight. The complexity and rigor in verifying the functionality of the FPGA warranted the use of the Universal Verification Methodology (UVM). In this paper we provide details of the main features of the FPGA as well as the verification architecture and strategies. We explore how we are able to achieve 100% functional coverage of the design’s intended functionality and state transitions in order to thoroughly vet the capabilities of the system.
    • 07.02 Peripheral Electronics and Data Handling for Space Applications Mark Post (University of Strathclyde) & Patrick Phelan (Southwest Research Institute)
      • 07.0201 Design and Analysis of RTOS and Interrupt Based Data Handling System for Nanosatellites Akshit Akhoury (Manipal Institute of Technology), Arun Ravi (MIT), Krishna Birla (Manipal Institute of Technology), Shaleen Kalsi (MIT, Manipal), Subhojit Ghorai (Manipal Institute of Technology), Rohit Sarkar (Manipal University) Presentation: Akshit Akhoury - -
        In this paper, we describe the design and working of the data handling system of a Nanosatellite that houses three interconnected microcontrollers, each present on a different PCB. Each microcontroller handles and performs a set of tasks to ensure the smooth and proper functioning of the satellite. A brief description of the evolution of the system organization and the motivation behind the choice of the microcontrollers has been provided. An in-depth explanation of the tasks and their distribution among the three microcontrollers follows.
      • 07.0202 Radiation Hardened High Speed Digitizer Robert Merl (Los Alamos National Laboratory) Presentation: Robert Merl - Monday, March 4th, 08:30 AM - Amphitheatre
        A space-flight quality digitizer board with a CompactPCI interface in the popular 6U form factor. Meets the requirements of missions requiring true space-grade radiation tolerance in geosynchronous orbits. Two giga samples per second. It has a reconfigurable radiation tolerant FPGA for on-orbit waveform processing.
      • 07.0203 Implementation of a Generic Payload Interface Unit for Agnostic Space Vehicles Patrick Phelan (Southwest Research Institute), Michael Epperly (Southwest Research Institute) Presentation: Patrick Phelan - Monday, March 4th, 08:55 AM - Amphitheatre
        An enabling technology platform, the Payload Interface Unit (PIU) is a simple, straight forward secure payload processor design that can service a variety of payloads and operate across virtually any orbit. The PIU design uses low-power electronics, low-mass structure and packaging, economical components and simple architecture to provide a highly capable interface unit. The PIU incorporates industry-standard digital interface(s) for both the payload and the Host Spacecraft and will be designed for standard spacecraft bus voltage. The PIU supports on-orbit operation in any Earth orbit, including Low Earth Orbit, Medium Earth Orbit, Highly Elliptical Orbit, and Geostationary Earth Orbit. The PIU architecture is capable of both embedding the payload data into the Host Spacecraft command and telemetry stream, or a dedicated communication link. This paper describes the implementation of the PIU, opportunities for further efficiency gains, and potential future capability growth.
    • 07.03 Memory and Data Storage for Space Applications Matthew Marinella (Sandia National Laboratories) & Michael Epperly (Southwest Research Institute)
      • 07.0301 Bringing 3D COTS DRAM Memory Cubes to Space Anthony Agnesina (Georgia Institute of Technology), Jim Yamaguchi (Irvine Sensors Corporation), Christian Krutzik (Irvine Sensors Corporation), Jean Yang Scharlotta (Jet Propulsion Laboratory), Sung Kyu Lim (Georgia Institute of Technology) Presentation: Anthony Agnesina - Monday, March 4th, 09:50 PM - Lake/Canyon
        Our paper presents a new architecture of space-grade 3D DRAM memory cubes. We detail the architectural choices and implementation challenges faced in the building and validation of our space-qualified 3D DRAM memory system, in an effort to offer high memory capacity, increased bandwidth, fault tolerance and improved size-weight-and-power characteristics needed for harsh space mission environments. Our novel horizontal 3D stacking technology called “Loaf-Of-Bread” (LOB) is used to integrate multiple Commercial-Off-The-Shelf (COTS) DRAM memory dies into a cube structure (3D-M3). A custom Radiation-Hardened-By-Design (RHBD) controller sitting underneath the cube supplements the 3D-M3 in addressing COTS radiation weaknesses by including advanced SEU and SEFI mitigation features such as error detection and correction, scrubbing, device data rebuilding and die management. We developed a custom DDR physical layer (PHY) for 14 independent dies to connect the 3D-M3 to its controller. Validation and functional evaluation of the ASIC controller will be conducted prior to tape-out on a custom FPGA-based emulator platform integrating the 3D-stack. The selected test methodology ensures high-quality RTL as well as allows to subject the cube structure to radiation testing. The proposed design concept allows for flexibility in the choice of the DRAM die in case of technology roadmap changes or unsatisfactory radiation results.
    • 07.04 Avionics for Small Satellites, Nano-Satellites, and CubeSats John Dickinson (Sandia National Laboratories) & James Lumpp (University of Kentucky)
      • 07.0401 Give Me More: Increasing Output for the Cyclone Global Navigation Satellite System (CYGNSS) Mission Robert Klar (Southwest Research Institute), William Wells (), Jillian Redfern (Southwest Research Institute), Ronnie Killough (Southwest Research Institute) Presentation: Robert Klar - Thursday, March 7th, 08:30 AM - Dunraven
        In December 2016, the National Aeronautics and Space Administration (NASA) launched a constellation of eight spacecraft for the Cyclone Global Navigation Satellite System (CYGNSS) mission in Low-Earth Orbit (LEO) at an inclination of 35 degrees. The mission’s science goal is to understand the coupling between ocean surface properties, moist atmospheric thermodynamics, radiation, and convective dynamics in the inner core of Tropical Cyclones (TCs). CYGNSS uses an innovative technique, Global Navigation Satellite System Reflectometry (GNSS-R), to derive surface wind speed by measuring the strength of the specular reflection of Global Positioning System (GPS) signals from the surface of the ocean. Despite limited onboard processing resources and relatively short ground station contacts, the CYGNSS data processing system has been effective – it has collected and successfully delivered to the science team hundreds of gigabytes of data in just eighteen months of operation. Since GNSS-R has proven useful, scientists are looking at other applications for observations over water and land. To make accurate measurements over land, it is of considerable interest to increase the data production rate for the Delay-Doppler Maps (DDMs), one of the chief onboard data products. This increase would significantly reduce the smearing effect that results from integrating over a longer time interval, resulting in higher-resolution imagery. This presentation reexamines the flight segment and ground segment data processing for CYGNSS. It considers some of the limiting constraints and explores some changes that have improved performance or may potentially improve it. For the flight segment, we evaluate enhancements such as alternative formatting and additional data compression. For the ground segment, we look at improved planning and increased ground contacts.
      • 07.0402 Solution to Data Congestion in Space Visweswaran Karunanithi (Technical University Delft/ Innovative Solutions In Space B.V) Presentation: Visweswaran Karunanithi - Thursday, March 7th, 08:55 AM - Dunraven
        A major paradigm shift is occurring in the type of missions carried-out by present nano/microsatellite missions. Between the years 2003 to 2014, the number of nano-satellite missions gradually grew, most of the missions during this period were either simple scientific missions from universities or one-off technology demonstration missions by industry startups. With the successful technology demonstrations of nano/microsatellite missions, 2015 to 2017 saw a major change in this field. The number of nano-satellites launched in 2017 nearly tripled compared to 2016, mainly because industries had started to develop constellation missions following the success of the earlier one-off missions. It is predicted that from now to 2022, ~72% of the nano/microsatellites launched will be either Earth observation (EO)/Remote Sensing (RS) constellations or Communication satellite constellations. The major bottle-neck for these missions of the future is the ability to down-link all the data generated on-board these satellites. Also, the present frequency spectrum allocations in S-band are not enough to meet the needs of future missions. So, there is a need to start investigating the use of Ka-band (20 to 30 GHz) frequency allocations to meet the communication technology demands of more complex missions lined-up in the coming decade. Also, with over $50B invested in the mega-constellations that intend to provide internet access from LEO (Low earth orbit)/ MEO (Medium Earth Orbit), there is a need to investigate if making use of this network could contribute to the solution for data congestion of nano/microsatellite missions. This work investigates the challenges of using Ka-band frequencies for nano/microsatellite gigabit-rate communications for three use-cases: 1) Direct satellite to ground links: A remote sensing application with a multi-spectral imaging payload is considered as a use-case to determine the requirements on the communication system; 2) Inter-satellite links: a swarm of nano-satellites forming a self-deploying sensor network for earth observation and radio astronomy is considered; and 3) LEO to LEO links: Internet-of-things (IOT)/Machine-to-Machine(M2M) services are considered as examples. Since this technology is intended for nano/micro satellites, power efficiency bandwidth efficiency, and radiation tolerance are very significant factors and this work makes a comparison of the present semiconductor technology to decide suitable candidates. Keywords: Nano-satellites, High data-rate communication systems, mmWave communications, Ka-band, DVB.S2, Mega-constellation, mmWave technology.
      • 07.0404 Towards an Integrated GPU Accelerated SoC as a Flight Computer for Small Satellites Caleb Adams (University of Georgia), Allen Spain (University of Georgia ), Jackson Parker (University of Georgia), Matthew Hevert (University of Georgia), David Cotten (University of Georgia), James Roach (University of Georgia) Presentation: Caleb Adams - Thursday, March 7th, 09:20 AM - Dunraven
        This presentation showcases some recent advancements in space based GPU / SoC processing systems developed / modified by the University of Georgia Small Satellite Research Laboratory. These systems are primarily focused on adapting existing terrestrial GPUs, such as the Nvidia Tegra X line, for LEO cubesat applications. Adapting such GPU technologies for space typically requires unique modifications to form factor, hardware design, and architecture. Furthermore, significant consideration is given to thermal and radiation mitigation in order for components to adapted successfully. Lastly, use cases for such systems will be discussed.
      • 07.0405 Accurate Star Tracker Simulation with On-Orbit Data Verification Laila Kazemi (Ryerson University), John Enright (Ryerson University) Presentation: Laila Kazemi - Thursday, March 7th, 09:45 AM - Dunraven
        This presentation will cover strategies to simulate high-fidelity star tracker images. Improving simulation fidelity enables better quantitative predictions of sensor performance, particularly during agile attitude maneuvers. These high-fidelity simulations use star tracker calibration parameters, detector sensitivity, and a simple representation of the spacecraft's attitude trajectories to synthesize images useful for detailed study of the star tracker accuracy and availability. The simulations include a variety of non-ideal imaging features such as pixel noise, vignetting, distortion, and nonlinear star tracks. The effectiveness of these high-fidelity simulations is assessed by comparing image features and processed sensor measurements obtained from synthetic images with those extracted from the laboratory, night-sky, and on-orbit sensor telemetry.
    • 07.05 Power Electronics for Space Applications Peter Wilson (University of Bath) & Christopher Iannello (NASA - NESC )
      • 07.0501 Mathematical Programming Based Approach to Modular Electric Power System Design Allen Flath (University of Kentucky), Aaron Cramer (), James Lumpp (University of Kentucky) Presentation: Allen Flath - -
        Satellite power systems can be understood as islanded dc microgrids supplied by specialized and coordinated solar cell arrays augmented by electrochemical battery systems to handle high-power loads and periods of eclipse. The periodic availability of power, the limited capacity of batteries, and the dependence of almost all mission service on power consumption create a unique situation in which temporal power and energy scarcity exist. Any satellite power system must be properly designed so the power generation and energy storage portions of the system have enough generation potential and storage capacity to reliably meet the load requirements of a given satellite mission. A multi-period model of an orbital satellite power system’s performance over a mission’s duration can be constructed. A modular power system architecture is used to characterize the system’s constraints. The periodic and generally predictable nature of a satellite’s mission environment provides a useful opportunity for these techniques. Using mathematical programming, an optimization problem can be posed such that the optimal power and energy ratings for the power system are determined for any load schedule imposed by a given mission’s requirements. The optimal energy trajectory of the electrical power system over a mission’s duration is also determined when the mathematical programming problem is solved. A generic set of mission requirements is identified to test this approach, but the objective function of the resulting optimization problem can be modified in order to return different results, and these differing results can provide a clear illustration of the trade-offs that designers of such power systems consider in the design process. For this paper specifically, this means that the same mission is evaluated in two ways for comparison: first by selecting the optimally-minimum mass, and then the optimally-minimum volume, of the system’s generation and battery elements. The design approach is demonstrated for a typical mission involving a CubeSat platform that periodically records image data and transfers this data once per-orbit.
    • 07.06 Electronics for Extreme Environments Mohammad Mojarradi (Jet Propulsion Laboratory)
      • 07.0601 Cold Survivable Distributed Motor Controller (CSDMC) Gary Bolotin (JPL), Gary Bolotin (Jet Propulsion Laboratory, California Institute of), Don Hunter (Jet Propulsion Labortory), Douglas Sheldon (Jet Propulsion Laboratory) Presentation: Gary Bolotin - Thursday, March 7th, 04:55 PM - Jefferson
        This paper presents the results of NASA’s COLDTECH development entitled “Cold Survivable Distributed Motor Controller (CSDMC)”. This work addresses the need for low mass, power and volume motor control electronics and its associated cabling. Landed payload mass of ocean world missions typically requires a spacecraft launch mass of 7-10x the landed mass due to the required propellant to get the payload to the surface. Reduction of landed mass leads to cheaper, more frequent missions and/or increased science return. This work addresses this need by developing a distributed electronics architecture, which places control and power electronics near or at actuators and instruments. The outcome of this effort will result in a 10X reduction in harness mass, enabling a significant increase in science payload which then enables more capable sample acquisition, delivery and analysis systems on these missions. Placing the control and power conversion electronics at or near the actuators or instruments is the cornerstone of our distributed architecture. To do this, we developed the technology necessary to distribute the electronics and place them on a shared interface and power bus. This enables a significant reduction in cable mass along with its associated complexity. This allows spacecraft designers to take advantage of volume at the extremities that would normally not be utilized. The challenge to meeting these goals is reducing the Space, Weight, and Power (SWaP) of the distributed electronics and adapting them to meet the requirements to survive the extreme temperature and radiation at the exposed extremities. We met these requirements by combining JPL s expertise in cold capable electronics, packaging and power conversion together with the state-of-the-art high density interconnect technology. This combination will result in a unique high density technology that extends the life of landed missions and also allows the missions to do more science through the mass and volume that is made available. In this paper we intend on discussing the technologies and system design to achieve these goals in support of ocean world missions. These technologies include the development of our motor control modules, a point of load regulator and isolated converter modules along with the packaging technology necessary to allow our electronics to survive the extreme temperatures.
      • 07.0602 Thermally-resilient COTS CMOS Sensor Packaging Approach for Mars2020 Enhanced Engineering Cameras Colin Mckinney (Jet Propulsion Laboratory) Presentation: Colin Mckinney - Thursday, March 7th, 05:20 PM - Jefferson
        The Mars2020 Enhanced Engineering Cameras (EECAMs) are a collection of medium- and wide-angle cameras used across the Mar2020 Flight System. The EECAMs use a commercial off the shelf (COTS) image sensor packaged in a 143-pin Ceramic Pin Grid Array (PGA). Early in the EECAM development, breadboard camera electronics that used conventional thru-hole soldering techniques was subjected to limited thermal cycling to investigate packaging survivability in Martian surface thermal environments from -135C to +70C. Functional testing following 2000 cycles showed that the detector was inoperable. Visual inspection of the part exhibited sever solder joint cracking in a substantial number of pins, and in some cases resulted in complete sheering of the pins from the ceramic package substrate. We will present the steps taken to derive the thermally-resilient electronics packaging design of the Mars2020 EECAM detector. We will highlight analyses and empirical test results that lead to a wide-temperature-survivable COTS component packaging design. Details of thermal cycle testing, in-process inspections, and final packaging design will be presented.
      • 07.0603 Modelling of Select Mixed-Signal Electronics for Cold Temperature Environments William Norton () Presentation: William Norton - Thursday, March 7th, 09:00 PM - Jefferson
        Future NASA missions will be subject to operating in extreme cold using mixed-signal electronic components. At present, models for mixed-signal components do not include significant temperature dependence, ADCs in particular. By developing comparatively generic models that are cold-capable, the ability to integrate mixed-signal parts into a larger system greatly increases. We have focused on Analog to Digital Converters (ADCs) because of their widespread, critical usage in avionic subsystems and lack of available cold macro models. This paper provides an overview of testing and modelling of a commercial off the shelf (COTS) ADC across cryogenic temperature for the purposes of trend identification, performance prediction and reliability scoping with possible post-correction capability. Testing of the device was made possible through development of an evaluation board that would service the circuitry requirements of multiple devices. Standard performance tests including sine wave FFT sweeps, best-fit sine histograms, and step responses provide information regarding part performance. To augment this information, we will perform additional tests including chirp input and changing clock duty cycle while implementing system identification of device behavior. These tests should permit a better understanding of the part and reveal degradation trends in a more descriptive way. We have not observed bit errors in testing thus far and we feel that these represent a serious degradation of device performance beyond that which a behavioral model can capture, especially in the absence of schematics or IBIS-type models. Because of this, effort focused on inclusion of various converter non-idealities and modeling of the front-end track and hold amplifier while assuming digital quantization to be ideal, a situation borne out so far. At the beginning of the project we constructed a simplistic model with only a priori information gleaned from existing literature, basic understanding of part internals, and datasheets. Since existing information regarding this ADC beyond its normal operating range is not available, there was considerable disagreement between predicted and measured results, and trend contributors were grossly misidentified. Once the model was calibrated according to measurements, there was much better agreement, including enhanced predictive capability regarding reference drift, static distortion, offset and gain error drift. Examination of the derived transfer function, drifting reference, and INL measurements present the possibility of post-correction for a given converter. The end result is a cold-capable behavioral model for an ADC that is user-tunable and allows one to examine the effects of different error sources on the device’s overall performance. Some of these error sources, such as jitter, aperture delay, and integral nonlinearity (INL) incorporate dynamic effects of the conversion process that are important in high-frequency communications applications. Others, such as offset error, gain error and reference drift, incorporate static effects that are of greater import in measurement applications. The development of this model will hopefully permit greater integration of commercial components in larger avionics systems, decreasing development time while increasing flexibility of designers when trying to meet mission objectives.
      • 07.0604 GaN Photodetector Measurements of UV Emission from a Gaseous CH4/O2 Hybrid Rocket Igniter Plume Hannah Alpert (Stanford University), Ashley Karp (Jet Propulsion Laboratory), Jason Rabinovitch (Jet Propulsion Laboratory, California Institute of Technology), Elizabeth Jens (Jet Propulsion Laboratory) Presentation: Hannah Alpert - Thursday, March 7th, 09:25 PM - Jefferson
        We present a gallium nitride (GaN) photodetector used to measure ultraviolet (UV) emissions from a hybrid rocket motor igniter plume. Owing to its wide (3.4 eV) and direct-tunable band gap, GaN is an excellent material platform for UV photodetectors. GaN is stable in radiation-rich and high-temperature environments, which makes photodetectors fabricated using this material useful for in-situ flame detection and combustion monitoring. The GaN photodetector we present has a record-high normalized photocurrent-to-dark current ratio (NPDR) of 6 x 1014 W-1, a peak responsivity of 7,800 A/W, and a UV-to-visible rejection ratio of 4 x 106; thus, the photodetector outputs a high signal with low quiescent power and little cross-sensitivity to visible light. Additionally, the high temperature properties of the GaN photodetector were investigated to evaluate its performance in extreme environment conditions. The photodetector shows operation at high temperatures (up to 250°C), with the NPDR still remaining above 109 W-1 at the higher temperatures, and the peak wavelength shifting from 362 nm to 375 nm at 250°C due to the change in bandgap. To measure the UV emissions from the hybrid rocket igniter plume, the photodetector was placed at three radial distances (3", 5.5", and 7") from the base of the plume, and the oxidizer-to-fuel ratio (O2/CH4) was varied to alter the size and strength of the plume. The current measured from the device was proportional to the intensity of the emission from the plume. The data demonstrates a clear trend of increasing current with increasing fuel concentration. Further, the current decreases with larger separation between the photodetector and the plume. A calibration curve constructed from the responsivity measurements taken over four orders of magnitude was used to convert the current into incident optical power. By treating the plume as a black body, and calculating a radiative configuration factor corresponding to the geometry of the plume and the detector, we calculated average plume temperatures at each of the three oxidizer-to-fuel ratios. The estimated plume temperatures were between 850 and 950 K for all three combustion conditions. The temperature is roughly invariant for a fixed fuel concentration for the three tested distances. These data demonstrate the functionality of GaN as a material platform for use in harsh environment flame monitoring.
      • 07.0607 A New Paradigm for Computing for Digital Electronics under Extreme Environments Naveen Kumar Macha (University of Missouri Kansas City), Bhavana Tejaswini Repalle (), Md Arif Iqbal (University of Missouri-Kansas City), Mostafizur Rahman (University of Missouri Kansas City) Presentation: Naveen Kumar Macha - Thursday, March 7th, 09:50 PM - Jefferson
        Digital CMOS based Integrated Circuits are susceptible to both permanent and transient errors in extreme environments like space due to radiation. The vulnerabilities arise mostly due to the static CMOS circuit style and use of planar devices, which can have junction breakdowns and latch-ups under radiation. These effects are expected to worsen with technology scaling. We propose a new computing fabric that not only provides a scalable alternative to traditional CMOS but also incorporates intrinsic fabric features for radiation resilience. A core component of the fabric is metallic nano-lines organized compactly. Whenever signal transitions take place in these metal lines, the sum of their crosstalk interference gets induced through virtual coupling capacitance in another metal line that was left floating (not connected to any signal/VDD/GND); in this case the transitioning signals are inputs and the net induced charge on the floating metal line is the output. Coupling strength between the input and output nano-lines and the net induced charge determines the logic being computed. The Crosstalk Computing fabric requires very few devices, which also implies less susceptibility. A byproduct of using interference for computing as opposed to device switching dependency is that whenever a high current spike is induced on interconnects due to radiation, the charges will get shared in multiple coupling capacitances connected to the net and thereby prevent extra charge build up at device nodes. Besides, the circuit style is dynamic as opposed to static CMOS, which also decreases the window of vulnerability. Moreover, the devices used in this fabric are ultra-thin body SOI Junction-less nanowire transistors where CMOS like latch-up mechanism is impossible as the substrate is not conductive. Our simulation results validate the concepts for radiation hardening and indicate potentials for huge improvements; for a full adder design, density benefit is over 5x. Under worse case radiation scenarios, the simulations show superior resilience compared to CMOS.
    • 07.07 Fault Tolerance, Autonomy, and Evolvability in Spacecraft and Instrument Avionics Didier Keymeulen (Jet Propulsion Laboratory) & Tom Hoffman (Jet Propulsion Laboratory)
      • 07.0702 Dynamic Fault Tree Analysis for a Distributed Onboard Computer Kilian Hoeflinger (German Aerospace Center - DLR), Sascha Müller (German Aerospace Center - DLR), Ting Peng (), Moritz Ulmer (German Aerospace Center (DLR)), Daniel Lüdtke (German Aerospace Center - DLR), Andreas Gerndt (German Aerospace Center) Presentation: Kilian Hoeflinger - Monday, March 4th, 11:00 AM - Gallatin
        Future space missions will demand greater capabilities regarding the processing of sensor data on onboard computers of satellites than current space technology can provide. Limited downlink bandwidth, high resolution sensors and more rigid real-time control algorithms, dedicated to increase satellite autonomy, drive the need for growing onboard computing performance. To overcome these challenges, new high-performance onboard computers are necessary, leading to an increased consideration of Commercial-Of-The-Shelf (COTS) components. The DLR project Scalable Onboard Computing for Space Avionics (ScOSA) targets these challenges with a complex onboard computer design consisting of space-qualified and COTS computing devices, arranged as heterogeneous SpaceWireinterconnected grid computer in space. However, the utilization of COTS components in the harsh space environment imposes new challenges on the system. Therefore, Fault Detection Isolation and Recovery (FDIR) mechanisms are important functionalities of systems like ScOSA. These enable the preservation of the demanded dependability levels for an embedded system in space. To ensure this dependability, the FDIR subsystem configuration requires a detailed analysis regarding potential faults in the system. For this purpose, we employed Dynamic Fault Tree (DFT) analysis, a methodology which is used to model faults and their temporal propagation through an onboard computer. With this paper, we contribute a new building block for showing the applicability of DFT analysis and for closing the gap between theory and practical application of DFTs. The quantitative results of the analysis of the contribution of the ScOSA FDIR subsystem to the overall system reliability are taken as baseline for a discussion on how to effectively improve the system’s reliability further. To showcase the methodology, an earth observation low earth orbit use case scenario is defined and the by FDIR means enforced processing system of the Xilinx Zynq SoC computing devices with a DFT analysis evaluated.
      • 07.0703 Automating and Integrating HW/SW Co-Verification with Embedded MPSoC Instrument Avionics Pamela Zhang (California Institute of Technology), Didier Keymeulen (Jet Propulsion Laboratory) Presentation: Pamela Zhang - Monday, March 4th, 11:25 AM - Gallatin
        The emergent technology of System-on-Chip (SoC) and UltraScale+ Multi processors system-on-chip (UltraScale+ MPSoC) devices promises lighter, smaller, cheaper, and more capable and reliable space electronic systems that could help to unveil some of the most treasured secrets in our universe. This technology is an improvement over the technology that is currently used in space applications, which lags behind state-of-the-art commercial-off-the-shelf (COTS) equipment by several generations. Soc and UltraScale+ MPSoC technology integrates all computational power required by next-generation space exploration science instruments onto a single chip. Unfortunately the traditional independent Ground Support Equipment (GSE) systems for testing this new extremely complex environment by acquisition, processing, and visualization of hyperspectral images can be prohibitive in terms of hardware, software and development time. This paper describes the new automation capabilities of hardware/software co-verification tools (LiveCheckHSI) for the Xilinx Zynq-based control and data handling avionics system that have been developed at the Jet Propulsion Laboratory (JPL) for next generation imaging spectrometers (NGIS). The flight NGIS avionics acquires and compresses images in real-time, in addition to programming the spectrometer (frame rate, exposure time), focus step motor, and heaters and reporting telemetry. The first part of the paper describes the automation tools integrated into the remote LiveCheckHSI such as AutoSweep, Record and Script. Beyond the SoC, the more recent emergence of UltraScale+ MPSoC technology combining heterogeneous supercomputing capability with high performance FPGAs allows for the integration of the LiveCheckHSI verification tools into the deployment device itself. This capability permits on-chip verification for flight systems and extends embedded testing and verification tools beyond the current pre-implementation formal verification and post-implementation HardwareDebug/Chipscope with hardware in the loop. The second part of the paper presents this concept by describing how the Yocto build system and the Qt C++ Framework creates an integrated on-chip LiveCheckHSI for hyperspectral image processing and visualization deployed UltraScale+ MPSoC. This paper presents successful leveraging of the quad core ARM 64-bit processor of the UltraScale+ MPSoC to execute real-time data processing and visualization using the Qt LiveView application. The software created in this process also follows the standards necessary to allow expansion and deployment on other devices.
    • 07.08 Guidance, Navigation, and Control Technologies for Space Applications John Enright (Ryerson University) & Giovanni Palmerini (Sapienza Universita' di Roma)
      • 07.0802 MEMS-based Gyro-stellar Inertial Attitude Estimate for NSPO Micro-Sat Program Yeongwei Wu (), Wei Ting Wei (NSPO) Presentation: Yeongwei Wu - Tuesday, March 5th, 08:30 AM - Madison
        The purposes of this paper are: (1) to examine the AOCS subsystem level performance (IAE accuracy) using the three-axis MEMS gyro arrays in the GS IAE design; (2) to address the subsystem level performance due to array misalignments and component temperature-dependent errors; and (3) to investigate various data fusion methods to optimize the IAE performance. This paper will describe: the preliminary AOCS design for the current Micro Satellite Program, the derivations of GS IAE and the analytical method used to assess the its performance using the MEMS gyro arrays; the lab-tested MEMS gyro’s performance data from Invensense MUP6000; the simulation results of various data fusion methods using a Matlab-based IAE simulation model; and our preliminary conclusions and recommendation for the micro-sat IAE design using MEMS gyro arrays.
      • 07.0803 Flight Performance Analysis of the CYGNSS microSatellites from On-orbit Telemetry Leena Singh (Lincoln Laboratory), Matthew Fritz (Charles Stark Draper Laboratory, Inc.) Presentation: Leena Singh - Tuesday, March 5th, 08:55 AM - Madison
        The Cyclone Global Navigation Satellite System constellation of eight micro-satellites in low-Earth orbit was designed to provide continuous, gap-free coverage for hurricane forecasting and monitoring throughout the life-cycle of a tropical storm. To provide this capability, the spacecraft Attitude Determination and Control System must accurately and reliably slew and hold its attitude - and by extension, its payload data collection antennae - to prescribed knowledge and pointing requirements. The CYGNSS constellation launched in December 2016 and has been collecting and serving data since the start of the tropical storm period in 2017. This paper presents the flight performance of the ADCS system in key ADCS modes and compares its on-orbit performance to its design and simulation predicted responses. Flight telemetry analysis uncovered an anomaly in one of the ADCS modes that interfered with the spacecraft’s observatory mode and induced a sustained, once-per-orbit pitch oscillation in all eight spacecraft. This anomaly was conjectured to trace to a spurious magnetic dipole induced on the spacecraft due to some electrical effects in the main power circuitry. This root-cause analysis is summarised in this paper as is the retuning that was undertaken on the estimation and control system parameters to improve disturbance prediction and rejection within the existing ADCS architecture. Data is presented from spacecraft simulations as well as flight, before and after the redesign, that shows the efficacy of the redesigned ADCS system to reject the spurious, anomalous disturbance and recover the required performance.
      • 07.0805 Fixed-time Attitude Control of Satellite Using Combined Magnetic and magneto-Coulombic Actuators Vijay Shankar Dwivedi (IIT Kanpur), Subham Dey (Birla Institute Technology Mesra), Salahudden Qazi (Indian Institute of Technology Kanpur), Dipak Giri () Presentation: Vijay Shankar Dwivedi - Tuesday, March 5th, 09:20 AM - Madison
        The salient contributions of the paper are: • The paper implements a hybrid actuation setup which is a combination of magnetic and magneto-Coulombic actuators. • The underactuation problem which had existed when magnetic and magneto-Coulombic actuators are used individually is also removed when hybrid actuator setup is implemented. • The paper proposes a fixed-time non-singular terminal sliding mode control algorithm for the satellite system actuated by hybrid actuators. • Numerical simulations validate the effectiveness of proposed control algorithm.
      • 07.0807 Optimal Solution for Torque Capability of Control Moment Gyroscopes David Elliott (Cornell University), Mason Peck (Cornell University), Issa Nesnas (Jet Propulsion Laboratory) Presentation: David Elliott - Tuesday, March 5th, 09:45 AM - Madison
        This paper improves the generality and performance of constraint-based steering laws for control moment gyroscopes (CMGs). Specifically, the paper provides analytical, closed-form gimbal-angle constraint functions that maximize the torque capability for arrays with parallel gimbal axes. The analytical solutions define an optimal gimbal-angle set for a given angular-momentum state for any planar array with four or more CMGs. Proofs verify the global optimality of the provided gimbal-angle set constraints for nearly all angular-momentum states. For angular-momentum states where an analytical proof is not provided, a numerical assessment provides evidence of global optimality. The solutions can be applied to planar and non-planar arrays consisting of planar segments of CMGs, such as roof arrays and box arrays. The gimbal-angle constraint functions also enable fault-tolerant steering laws because the constraint functions apply to any number of planar CMGs greater than four. Thus, if one or more CMGs fail, the resulting steering law can still perform optimally. The gimbal-angle constraint functions are broadly applicable to aerospace and robotics problems. In their more general form, these constraints optimize velocity-tracking capability of planar serial manipulators, which benefits tasks requiring large velocities of the end effector, such as rapid mobile manipulation and intercepting fast-moving objects. Due to their generality, the constraint functions are applicable to hyper-redundant multi-degree-of-freedom systems, including elephant trunks and snake-like robots. Simulations comparing the performance of this approach to that of existing constraint-based methods illustrate the improvements.
      • 07.0811 ESTCube-2 Attitude Determination and Control: Step towards Interplanetary CubeSats Andris Slavinskis (Tartu Observatory/NASA Ames Research Center), Ikechukwu Ofodile (University of Tartu), Hendrik Ehrpais () Presentation: Andris Slavinskis - Tuesday, March 5th, 10:10 AM - Madison
        Utilization of satellites to meet the needs of various missions requires a reliable Attitude Determination and Control System (ADCS). In this paper, we presents a robust design of the ADCS for the ESTCube-2 nanosatellite. The primary aim of the ADCS is to provide angular momentum to deploy a 300-meter tether used in a plasma brake deorbiting experiment. This is achieved by spinning up the three-unit CubeSat to 360 degrees per second about the short axis, deploying the tether and repeating the spin-up–deployment sequence until the whole tether is deployed. The system also provides accurate pointing for an Earth observation camera and a high-speed communication system. In addition to basic sensors and actuators commonly used on nanosatellites, the design includes a cold-gas propulsion system and a star tracker which will be tested for the future use in deep space. In order to operate the Earth observation and high-speed communication payloads, the satellite will use reaction wheels and the star tracker to achieve pointing the accuracy better than 0.25 degrees and the stability better than 0.125 degrees per second. To achieve the control requirements, a Lyapunov-based stability function and an optimal linear–quadratic regulator control is implemented. The attitude determination is handled by an unscented Kalman filter, which is deployed on a Cortex-M7 microcontroller. The ESTCube-2's plasma brake experiment in low Earth orbit serves as a precursor of ESTCube-3 which will test similar technology – the electric solar wind sail – for interplanetary propulsion in lunar orbit.
    • 07.09 Emerging Technologies for Space Applications William Jackson (Sierra Nevada Corp.) & Michael Mclelland (Southwest Research Institute)
      • 07.0901 High Performance Transmitters for Small Satellites for Data Transmission and Remote Sensing Naresh Deo () Presentation: Naresh Deo - Friday, March 8th, 08:30 AM - Amphitheatre
        This decade has witnessed an explosive growth in the planning and deployment of entire constellations of CubeSats and other small satellites (SmallSat) for a multitude of functions and missions. Some of the most notable missions include: space situational awareness, environmental research and climate studies, global weather monitoring, , earth observation and video imaging/mapping, communication networks, data communications, relays or inter-satellite links and remote sensing among many others. Most of the payloads on these SmallSat generate massive amounts of data at a high rate. This large volume of data must be downloaded to their earth stations in a reliable and efficient manner often in real-time. Presently, majority of data links available for CubeSats and other SmallSat are limited to relatively low data rates (well below a GB/s) and operate at relatively low microwave frequencies at or below X-band (10 GHz). Therefore, a new generation of compact, high performance and efficient microwave and millimeter-wave transmitters are needed for effective data transfer or communication for these satellites. Also, high power transmitters are of critical importance for small satellite-based microwave or millimeter-wave radars and sensors. Higher transmitter frequencies offer added benefit of smaller antenna size in the space-constrained environment of SmallSats. This paper presents novel approaches for realizing such transmitters using solid-state power amplifiers integrated with miniaturized upconverters or modulators suitable for space use. They involve a unique and optimal combination of modular design using highly efficient solid-state amplifier devices, compact construction using light-weight materials and novel low-cost manufacturing methods. The primary vision of this development is to standardize these transmitters as commercial off the shelf (COTS) parts and mass produce them for integration with the remaining payload by SmallSat developers and users. Designs, implementation methods and measured results for several transmitters operating in the Ka-band (25-28 GHz), Q-band (37-42 GHz) and beyond are described in this paper. Future trends and prospects for development of the next generation of such transmitters is also presented.
      • 07.0902 On-board Wireless Communications for Spacecraft Test and Operations Norman Lay (Jet Propulsion Laboratory), Yu Ming Yang (NASA Jet Propulsion Lab), Clayton Okino (Jet Propulsion Laboratory), Colin Mckinney (Jet Propulsion Laboratory), Arby Argueta (), Ryan Rogalin (NASA Jet Propulsion Lab), Neil Chamberlain (Jet Propulsion Laboratory), Kristoffer Bruvold (Jet Propulsion Laboratory), Gregory Miles (), Daniel Cho (NASA Jet Propulsion Lab), William Walsh () Presentation: Norman Lay - -
        This paper discusses recent activities at JPL that are focused on the development of wireless communications for data path connectivity between instruments and subsystems within the confines of a single spacecraft. Anticipated benefits of intra-spacecraft wireless links include reduction of cable mass, improved flexibility in spacecraft design or modifications and increased efficiencies during integration and test. This paper describes the framework for this effort, plans for retiring key risks and progress to date. Three of the primary risks addressed under this effort are communications link reliability, scalability and electromagnetic compatibility. In this paper, we will discuss analysis and test methods used to investigate each of these areas. In addition, we will describe a number of use cases for both operational and test applications that are under current investigation and development.
      • 07.0903 Introduction to Space Dogfighting -- What Matters in Space Engagements Oleg Yakimenko (Naval Postgraduate School), Edward Hanlon (United States Navy) Presentation: Oleg Yakimenko - Friday, March 8th, 08:55 AM - Amphitheatre
        Spacecraft play an increasingly significant role in United States government military operations. For adversaries looking to degrade U.S. capability to mitigate tactical advantage, this reliance provides another attack vector and represents a potential U.S. weakness. Recent technological developments have resulted in the increased proliferation of “attack” satellites. A strong understanding of the orbital domain and orbital dynamics is necessary to effectively evade these attackers. Much like the early days of aviation, space innovation has out-paced existing tactics, techniques and procedures. This paper aims to provide an overview of the domain and possible evasive maneuvers to facilitate further tactics development. It begins with an overview of the threat landscape to provide background on what to expect, and proceeds to discuss what positions of advantage are in space and how thrust commands translate to maneuvers at different time scales. It details the development of an engagement simulator and provides insight as to the effect of various evasion thrust patterns. From this, an evasion tactic is developed and tested in the simulator. This tactic proves effective in evading an aggressor, while also demonstrating substantial fuel savings over alternative methods. Finally, different spacecraft parameters are compared to determine what hardware improvements provide the best evasive capability.
      • 07.0905 Streamlining High Altitude Ballooning Missions: From Payload, to Launch, to Flight Hunter Hall (NASA Jet Propulsion Lab), Rohan Daruwala (University of Wisconsin), Trey Fortmuller (UC Berkeley), Ethan Prober (University of Michigan), Samar Mathur (University of Houston), Kathryn Kwiecinski (University of Minnesota), Makena Fetzer (UC Berkeley), Ariel Kohanim (JPL), Benjamin Donitz (University of Michigan), William Bensky (University of Southern California), Bryan Lara Tovar (NASA Jet Propulsion Lab), Adrian Stoica (Jet Propulsion Laboratory) Presentation: Hunter Hall - Friday, March 8th, 09:20 AM - Amphitheatre
        High-altitude balloons (HAB) have long been used to explore Earth's atmosphere and study the surface of Earth from above. Their applications have bifurcated into two camps, one belonging to hobbyists launching balloons for recreation and simple experimentation, and the other belonging to researchers launching expensive, long-duration missions with support from national laboratories and universities. Over the Summers of 2017 and 2018, student interns at the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) bridged the gap between these discrete camps by developing a low-cost yet reliable high-altitude scientific balloon payload, Zephyrus, and launch system, Talos, to serve the scientific community at JPL and elsewhere. A typical hobbyist stratospheric balloon reaches an altitude of about 35 kilometers (120,000 feet) and operates for two to six hours, depending on ascent rate and weather conditions. This altitude environment and mission time-span is ideal for many scientific experiments and technology demonstrations. By reducing labor costs, time, and expertise required, Talos and Zephyrus enable more researchers to test their innovations and experiments more frequently and with less overhead.
    • 07.10 COTS Utilization for Reliable Space Applications Harald Schone (Jet Propulsion Laboratory) & Douglas Carssow (Naval Research Laboratory)
      • 07.1001 Analysis and Comparison of Calibration Techniques for COTS Sensors Onboard a Nanosatellite Shivika Singh (Manipal Institute of Technology ), Akshit Akhoury (Manipal Institute of Technology), Arun Ravi (MIT), Paras Shah (Manipal Institute of Technology ), Sushmita Gosavi (MANIPAL INSTITUTE OF TECHNOLOGY), Sahil Joshi (), Disha Gundecha (), Nishant Gavhane (Manipal Institute of technology) Presentation: Shivika Singh - -
        This paper explains and compares the different methods that could be used to characterize and calibrate COTS sensors onboard a 2U class nanosatellite. Attitude sensors are used in satellite missions for determination of attitude in orbit and then using this information for controlling the satellite for effective payload action. The paper focuses on the two major sensors on board; the Anisotropic Magnetoresistance (AMR) Magnetometer and a Micro-Electro-Mechanical Systems (MEMS) Gyroscope. The COTS sensors tend to have manufacturing defects which lead to internal errors and external factors like temperature adding to the deviation from the true value. A robust explanation of the factors affecting the sensor values and a corresponding functioning of the mathematical model built on the various internal sources of error and external stimulants which affect the output of these sensors is provided. In contrast to mathematical modeling, an offboard neural network uses the method of backpropagation for defining a nonlinear relationship between the raw sensor values and the actual values. The calibrated values obtained from the application of the mathematical error model and the neural network is presented through a series of graphs. Further critical analyses of the plots are done to obtain the best method to calibrate the particular sensor. This systematic calibration aids in improving the attitude estimation and control design of the satellite further leading to enhanced control on payload action. This enables the low-cost COTS sensors to be used in aerospace applications.
      • 07.1002 FLASHRAD: A Reliable 3D Rad Hard Flash Memory Cube Utilizing COTS for Space Applications Da Eun Shim (Georgia Tech), Amanvir Sidana (Samsung Austin Semiconductor), Jim Yamaguchi (Irvine Sensors Corporation), Christian Krutzik (Irvine Sensors Corporation), Sung Kyu Lim (Georgia Institute of Technology) Presentation: Sung Kyu Lim - Friday, March 8th, 09:45 AM - Amphitheatre
        We propose a method to effectively increase data storage for onboard memory while reducing the cost and effort that goes into design by presenting a 3D memory cube design utilizing 24 COTS NAND flash dies in a LOB configuration. The design includes various features that increase the data storage available while considering hazards specifically in space environments such as errors from single event effects (SEE) or single event functional interrupt (SEFI) events. Currently, the preliminary RTL code is ready with support for NAND Flash commands, error-correcting codes (ECC), and scrubbing. Features such as wear leveling, bad block management, data scrambling and a serial rapid IO (SRIO) interface to further mitigate errors due to radiation effects in the space environment will be incorporated in the future. The functionality of the memory controller has been verified via simulation of the RTL code. Further validation and testing using a FPGA board are also underway to verify the design at this stage. Therefore the proposed design addresses the need for increased memory storage while also allowing COTS dies to be used. This paves way for reduced design efforts as well as the incorporation of state-of-the-art memory dies in space missions.
      • 07.1003 Non-Radiation Tolerant COTS Power Converters in Low Earth Orbit Timothy Babich (Naval Research Laboratory ) Presentation: Timothy Babich - Friday, March 8th, 10:10 AM - Amphitheatre
        Commercial DC-DC power converters and filters were successfully used in the power supply of a Space Test Program (STP) mission on the International Space Station (ISS). The mission lifetime was designated for one year and the electronics have been operational in space since February of 2017. Resource limitations, particularly cost and time constraints, prompted the decision to use commercial, non-space qualified, components. The particular parts used were Vicor V110A28M400BS DC-DC power converters and FIAM110MS1 filters. This document will summarize the risks and challenges involved with using the commercial parts as well as measures taken to mitigate these risks. The mission requirement was to convert a 120 bus to 28V DC power for STP-H5 science experiments. Baseline designs planned to utilize a secondary bus on the ISS to provide the 28V power. However, performance limitations of the secondary bus were later identified and prompted concern that the scientific objectives of the mission could be subsequently hindered. The best solution was to add a separate 120V to 28V DC-DC power converters to an electronics box already in development, thus eliminating dependence on the existing 28V bus. Conventional flight qualified power supplies could not be obtained within the constraints of the mission. Several vendors were considered, but none could produce the power converters as quickly as needed. A custom designed power supply was considered as well, but resources, packaging challenges, and lead times for individual EEE parts made this approach unviable. Several other organizations were also contacted to consider using parts that had been purchased as flight-spares for other programs. It was determined that flight qualified power converters could not be obtained for this mission and commercial parts became the only viable option. A radiation study was conducted based on the orbit, mission life, and thickness of the electronics box that would house the power converters and corresponding filters. A relatively small total dose was predicted and the decision was made to move forward with commercial parts. As the designed moved forward, other studies and tests were conducted to mitigate risk as much as possible.
      • 07.1004 Evaluating Commercial Processors for Spaceflight with the Heterogeneous On-Orbit Processing Engine Tyler Lovelly (Air Force Research Laboratory), Jesse Mee (AFRL/RVSE), James Lyke (Space Vehicles Directorate), Andrew Pineda (Air Force Research Laboratory), Ken Bole (AFRL Space Vehicles), Robert Pugh (Think Strategically, LLC) Presentation: Tyler Lovelly - Friday, March 8th, 10:35 AM - Amphitheatre
        A concept is presented to evaluate the potential for diverse collections of state-of-the-art commercial electronics, managed by a radiation-hardened supervisor, to operate reliably in a space radiation environment and to off-load the compute-intensive processing tasks from less-capable satellites when communication with ground stations is unsuitable or unavailable. The Heterogeneous On-Orbit Processing Engine (HOPE) is introduced as an on-orbit computing resource developed specifically for spaceflight testing and use with diverse collections of commercial processors such as multi-core central processing units, field-programmable gate arrays, and graphics-processing units, where each constituent architecture can be called upon to support the applications for which it is best suited. Additionally, the commercial electronics can be continuously monitored, controlled, and examined to determine the extent to which these terrestrial technologies can survive in the harsh radiation environment of space. These concepts and technologies will first be developed and analyzed in a “flat-sat” laboratory environment, then as a low Earth orbit spaceflight experiment (HOPESAT-1) supporting one or more networked satellites, and finally with follow-on missions featuring different electronics. Successful development of this computing resource and the resulting spaceflight data will enable future space system concepts to reliably perform on-orbit processing with state-of-the-art commercial technology.
  • 8 Spacecraft & Launch Vehicle Systems & Technologies Robert Gershman (JPL) & Bret Drake (The Aerospace Corporation)
    • 08.01 Human Exploration Beyond Low Earth Orbit Bret Drake (The Aerospace Corporation) & John Guidi (NASA) & Kevin Post (The Boeing Company)
      • 08.01 Keynote 8.01: Update on NASA’s Exploration Campaign Marshall Smith Presentation: Marshall Smith - - Jefferson
        NASA is planning to return to the Moon for the long term while preparing for missions into the solar system, with the next goal Mars. NASA Headquarters will present their newest Exploration Campaign for a scientific and human return to the Moon and the lunar surface.
      • 08.0101 Summary of Gateway Power and Propulsion Element Studies David Irimies (NASA Glenn Research Center), David Manzella (NASA - Glenn Research Center), Timothy Ferlin () Presentation: David Irimies - Monday, March 4th, 10:10 AM - Jefferson
        NASA’s Power and Propulsion Element (PPE) is based on a joint industry/NASA demonstration of an advanced solar electric propulsion powered spacecraft to meet commercial and NASA objectives. The PPE can establish the initial presence in cislunar space for the Gateway through initial operations and the subsequent deployment of additional partner-provided elements for the cislunar platform. Five commercial vendors were selected to conduct PPE studies which addressed key drivers for PPE development and support for the Gateway concept formulation. The study vendors focused on their performance trades and assessing their strategic capabilities, leveraging their existing and planned capabilities for PPE development. The industry studies examined differences between prior Solar Electric Propulsion (SEP) mission concepts, expected industry capabilities, and potential needs supporting NASA’s Gateway concept. These studies provided data on commercial capabilities relevant to NASA’s exploration needs and reduced risk for a new, powerful, and efficient SEP-based PPE spacecraft.
      • 08.0102 The NASA SLS Exploration Upper Stage Development & Mission Opportunities Ben Donahue (Boeing Company) Presentation: Ben Donahue - Monday, March 4th, 09:20 AM - Jefferson
        The new NASA Exploration Upper Stage (EUS) will evolve the Space Launch System (SLS) to a significantly higher performance level than the current SLS Block 1 configuration. The large throw mass of the Block 1B provides a game-changing capability for the exploration of other worlds. By enabling larger margins in the design of exploration platforms and the ability to send multiple copies of atmospheric and surface probes, higher resolution spatial and temporal data can be collected in a single mission. Mission risk can be reduced by increasing the redundancy of each individual system and the architecture by using multiple copies of the same systems. The EUS will provide the SLS the capability of achieving greater human exploration, operations and science objectives for 2020-2040 era Beyond Earth Orbit (BEO) missions, including crewed Cis-lunar missions in the mid-2020s, crewed Lunar Surface missions in the late 2020’s and crewed Mars missions in the mid-2030s.
      • 08.0103 Lander and Cislunar Gateway Architecture Concepts for Lunar Exploration Xavier Simón (Boeing Company), Travis Moseman (Boeing Company), Matthew Duggan (The Boeing Company) Presentation: Xavier Simón - Monday, March 4th, 09:45 AM - Jefferson
        This paper describes a progressive series of increasingly capable missions, utilizing the Gateway for robotic and human surface lander missions, and discusses the implications of various choices in developing a lunar exploration architecture. The importance and value of a Gateway to all exploration options are examined and compared to direct exploration of the lunar surface. Finally, the commercial options and advantages of a robust deep space architecture are discussed.
      • 08.0106 An Introduction to the Concept of a Deep Space Science Vessel Robert Howard (NASA Johnson Space Center) Presentation: Robert Howard - Monday, March 4th, 11:00 AM - Jefferson
        Once, the goal for human spaceflight was to put a man in space. Then the goal was to put a man on the Moon and return him safely. Today, as we prepare to return to the Moon, our eyes are also set on Mars. But can the vision for human spaceflight expand to include the entire inner solar system? Could we have human spaceflight dedicated to deep space science throughout the inner solar system, not just on the Moon and Mars? What kind of habitation system could enable a large group of humans to live and work while traversing orbits between Mercury and Ceres?
      • 08.0107 NASA’s Gateway: An Update on Progress and Plans for Extending Human Presence to Cislunar Space Nicole Herrmann (Valador), Jason Crusan (NASA - Headquarters), Marshall Smith (NASA HQ), Erin Mahoney (Stellar Solutions, Inc. ), Kandyce Goodliff (NASA), Jacob Bleacher (NASA - Goddard Space Flight Center), Jose Caram (NASA - Johnson Space Center), Douglas Craig (NASA) Presentation: Douglas Craig - Monday, March 4th, 08:55 AM - Jefferson
        As reflected in NASA's Exploration Campaign, the next step in human spaceflight is the development and deployment of a deep space Gateway – a cislunar outpost to advance America’s human return to the surface of the Moon, and drive exploration and science activity in deep space. Together with the Space Launch System (SLS) and Orion, the Gateway is central to advancing and sustaining human space exploration goals, and is the unifying single stepping off point in our architecture for human cislunar operations, lunar surface access and missions to Mars. NASA will lead this next step and will serve as the integrator of the spaceflight capabilities and contributions of U.S. commercial partners and international partners to develop the Gateway. Through partnerships both domestic and international, the Gateway team will bring innovation and new approaches to the advancement of U.S. Government, industry and global spaceflight goals and objectives. The Gateway will be developed in a manner that will allow future capabilities and collaborations with U.S. Government, private sector companies, and international partners. The current Gateway concept distributes necessary functions across Gateway, including: power and propulsion (and communication), habitation/utilization, logistics resupply, airlock, and robotics. The functional goal is to develop an effective habitation/utilization capability comprised of pressurized volume(s) with integrated habitation systems and components, docking ports, environmental control and life support systems (ECLSS), avionics and control systems, radiation mitigation and monitoring, fire safety systems, autonomous capabilities, utilization, and crew health capabilities, including exercise equipment. Studies of the architecture trade space and potential Gateway configurations have revealed a baseline concept that can satisfy the aforementioned functions as well as achieve U.S. and international partner objectives. Through analysis, several Gateway configurations were identified that could meet these functions and objectives to varying degrees. This paper will provide an update on the Gateway configuration including U.S. and international element partners, status of acquisition activities, progress of the Power and Propulsion Element development; and updates on plans for Gateway utilization activity planning.
      • 08.0108 SLS, the Gateway, and a Lunar Outpost in the Early 2030s on the Way to Mars Terry Haws (Northrop Grumman Corporation), Mike Fuller (Orbital ATK) Presentation: Terry Haws - Monday, March 4th, 10:35 AM - Jefferson
        This paper discusses potential near-term missions that leverage Orion and SLS, as well as the Lunar Orbital Platform – Gateway, in order to establish an outpost on the lunar surface, as part of the overall campaign to eventually reach Mars. This proposed campaign of lunar surface missions will create an outpost that can then be resupplied by commercial cargo and crew providers, while SLS and Orion continue to deliver the large components needed at the Gateway to test Mars exploration systems, finally culminating in a crewed Mars mission.
      • 08.0110 Opportunities and Challenges of a Common Habitat for Transit and Surface Operations Robert Howard (NASA Johnson Space Center) Presentation: Robert Howard - Monday, March 4th, 11:25 AM - Jefferson
        Is it possible for a single habitat design to be applied to the unique missions of lunar surface habitat, Mars transit vehicle, and Mars surface habitat? If so, can the SLS Core Stage LOX tank serve as the primary pressure vessel, making this a monolithic habitat? Should the internal orientation be vertical or horizontal? Can the vessel accommodate a crew size of four? Of eight? Can such a large structure be integrated with a lander spacecraft? These are the opportunities and challenges of a common habitat for transit and surface operations.
      • 08.0111 NASA’s Space Launch System: Enabling a New Generation of Lunar Exploration Stephen Creech (NASA - Marshall Space Flight Center) Presentation: David Smith - Monday, March 4th, 11:50 AM - Jefferson
        Following two decades of operational experience in low-Earth orbit (LEO), NASA has turned its focus once again to deep space exploration. The Agency is building the Space Launch System (SLS) to take astronauts and cargo to the Moon and send robotic spacecraft deep into the solar system. Offering unmatched performance, departure energy and payload capacity, SLS is designed to evolve into progressively more powerful configurations, enabling a new generation of human exploration of the Moon in preparation for future missions to Mars. The first build of the Block 1 vehicle is nearly complete for Exploration Mission-1 (EM-1), the first integrated flight of SLS and the Orion crew vehicle. EM-1 will send an uncrewed Orion to a distant retrograde lunar orbit in order to test and verify new systems, and along the way will deploy 13 6U-class CubeSats in deep space along the upper stage disposal trajectory after separation from Orion. The Agency’s current plans call for the first three missions on the SLS manifest to utilize the Block 1 vehicle in crew and cargo configurations. A more powerful evolved vehicle, Block 1B, will provide additional mass and volume performance using a new Exploration Upper Stage (EUS). Block 1B will lift 34 to 40 metric tons (t) to trans-lunar injection (TLI), depending on crew or cargo configuration. The Block 1B crew configuration will offer as much payload volume as industry-standard 5 m-diameter fairings to co-manifested payloads in a Universal Stage Adapter (USA). The Block 1B cargo variant will accommodate 8.4 m-diameter fairings in 62.7-foot (19.1 m) or 90-foot (27.4 m) lengths. Adding smallsat secondary payloads to ride along with primary and co-manifested payloads on future flights may be possible, depending on mass margins. Leveraging a flight-proven, well-understood propulsion system, SLS’s flexible architecture, unmatched performance and expansive payload accommodations will open exciting new mission possibilities in deep space. Launches of habitat modules for NASA’s new Gateway lunar outpost, the next generation of robotic spacecraft to the far reaches of the solar system, large-aperture deep space telescopes, probes to interstellar space and the return of astronauts to the Moon are all possible with SLS.
      • 08.0112 NASA’s Exploration Mission Strategy Marshall Smith (NASA HQ) Presentation: Marshall Smith - Monday, March 4th, 04:30 PM - Gallatin
        NASA is embarking on the next step in human exploration by building systems that will allow humans to live and work in deep space to develop the skills necessary to take human presence into the solar system. The initial systems in development are the Space Launch System (SLS) vehicle, necessary to launch payloads to cislunar destinations and beyond, the Orion crew vehicle which will serve as the spacecraft capable of transporting humans to these deep space locations, and the Gateway, a short-term habitation system to be built and operated in cislunar space. Supporting these systems are the ground and flight operations capabilities provided by the Exploration Ground Systems (EGS) at Cape Canaveral, Florida and Flight Operations team in Houston, Texas. These systems will place the first toe-hold in deep space, where we will begin to learn how to live and work in these harsh environments. These systems will also enable the scientific and commercial development of deep space through supporting lunar landers, Lunar and Mars sample return missions as well as lunar habitation and surface operations. Together NASA, along with its international partners will develop, deliver and operate these systems to permanently extend human presence in the lunar vicinity and into deep space. This paper will present an overview of the exploration mission strategy, the initial Orion and SLS test flights and the buildup plans of the Gateway in cislunar space. It will discuss the two flight test missions, Exploration Mission-1 (EM-1) and EM-2 in detail, giving an overview of the uncrewed EM-1 mission and the crewed EM-2 mission, describing the flight phases for each mission, from launch through spacecraft recovery operations. Looking beyond the initial test flights, this paper will also present the concept of operations for missions beyond EM-2, which will serve to assemble the Gateway and then use it for human and robotic exploration. It will also detail the maturation of SLS and Orion capabilities that will support the planned Gateway exploration missions.
    • 08.02 Human Exploration Systems Technology Development Stephen Gaddis (NASA - Langley Research Center) & Jonette Stecklein (NASA - Johnson Space Center) & Andrew Petro (NASA - Headquarters)
      • 08.02 8.02 Keynote Human Exploration Systems Technology Development Andrew Petro Presentation: Andrew Petro - - Madison
        Andrew Petro (session co-chair) NASA Headquarters, Space Technology Mission Directorate. This keynote presentation will outline the scope of NASA technology development activities related to human exploration with an emphasis on projects managed by the Space Technology Mission Directorate. The presentation will include a summary of the space technology strategic framework and the key capabilities that have been prioritized for advancement, in particular the technology challenges that relate most directly to the lunar exploration campaign.
      • 08.0204 Recent Advancements in Modeling and Simulation of Entry Systems at NASA Michael Barnhardt (NASA), Michael Wright (NASA Ames Research Center) Presentation: Michael Barnhardt - Wednesday, March 6th, 08:55 AM - Madison
        This paper summarizes recent investments by NASA's Entry Systems Modeling Project to advance modeling and simulation of entry systems. Investments are made in four core technical areas with additional investments made for specific technologies as opportunity and need arise. The four core technical areas are: (1) Predictive Material Modeling; (2) Shock Layer Kinetics & Radiation; (3) Computational & Experimental Aerosciences; and (4) Guidance, Navigation, & Control. The Predictive Material Modeling technical area develops multi-scale techniques for modeling thermal protection material properties and behavior. Microscale simulations determine fundamental properties at the constituent material level, which are then upscaled for use in applications at the macro (system) scale. Two parallel approaches are used at the macroscale. The first is a highly detailed model that incorporates as much physics as possible in order to assess system sensitivities and uncertainties. The second approach is an engineering model - a carefully selected subset of the detailed model - which combines suitable accuracy and computational efficiency for engineering applications. Shock Layer Kinetics & Radiation combines computational chemistry, fundamental experiments, and applied modeling in order to improve accuracy and reduce uncertainties associated with shock layer radiation encountered during EDL throughout the Solar System. Computational & Experimental Aerosciences is the broadest technical area due to its influence across many disparate subsystems of the EDL process. Investments in this area are chosen to closely align with the prime technical challenges determined. Current technologies under development include: Magnetic suspension wind tunnels; Free-flight CFD for determination of vehicle dynamics; Parachute inflation and descent dynamics modeling; Turbulent heating augmentation due to tiled and woven thermal protection system roughness patterns; and advanced numerical techniques for solving equations more accurately than ever before. The Guidance, Navigation & Control technical area is developing guidance and control techniques for precision landing of heavy payloads on Mars and other destinations. In addition to the core technical areas, the Entry Systems Modeling Project is investing in two special topics. The PICA-NuSil effort seeks to develop a high-fidelity model of PICA coated in NuSil for the purpose of meeting post-flight reconstruction accuracy requirements for Mars 2020's instrumentation, MEDLI-2. The Arc Heater Simulator (ARCHeS) is a general-purpose model of plasma with specific application to understanding dynamics and performance of arc jets used to evaluate thermal protection materials.
      • 08.0205 System Integration Comparison between Inflatable and Metallic Spacecraft Structures Gerard Valle (NASA/JSC), Douglas Litteken (), Thomas Jones (NASA - Langley Research Center), John Zipay (NASA - Johnson Space Center), Eric Christiansen (NASA Johnson Space Center) Presentation: Gerard Valle - Wednesday, March 6th, 09:20 AM - Madison
        Inflatable spacecraft structures are an alternative to traditional pressurized metallic structures that provide significant launch volume savings. A flexible primary structure, however, has a number of design and construction details that must be considered when moving from a metallic architecture to one based on softgoods. It is not only necessary to compare the structural mass and volume differences, but also examine the overall system integration changes that are required to implement a large-scale inflatable spacecraft. This paper compares inflatables with traditional metallic spacecraft by reviewing the integration of sub-systems in each vehicle and identifying the key differences. Additionally ground integration and prelaunch considerations are detailed, along with differences in requirements for environmental and human factors. The paper concludes with a discussion of future in-space and surface applications for inflatable structures.
      • 08.0208 Self-Assembling Space Habitats:TESSERAE Technology and Mission Architecture for Zero-g Construction Ariel Ekblaw (MIT ) Presentation: Ariel Ekblaw - Wednesday, March 6th, 09:45 AM - Madison
        Designs for adaptive, modular, and re-configurable space structures hold great promise for the evolving commercial space station market in LEO (Low Earth Orbit), for supporting Lunar Orbital Platform-Gateway designs, and for facilitating the first human Mars missions. We propose an extensible self-assembly paradigm for in-orbit space habitat construction, discuss mission architectures uniquely facilitated by this approach to habitat design, and present a feasibility review and preliminary results from a proof-of-concept prototype. This paper details our habitat design and deployment planning around TESSERAE (Tessellated Electromagnetic Space Structures for the Exploration of Reconfigurable, Adaptive Environments). This technology demonstration mission explores several parameters for a self-assembling system (quasi-stochastic assembly, electro-mechanical bonding, clamping processes, responsive sensing and autonomous GNC, etc.) and includes a multi-year research effort to engineer and deploy test structures. The first prototype was successfully tested on a parabolic flight in November 2017 and is now scheduled for a second parabolic flight and initial sub-orbital launch in 2019.
      • 08.0210 Booster Obsolescence and Life Extension of SLS Boosters David Griffin (Northrop Grumman Corporation), Terry Haws (Northrop Grumman Corporation), Mike Fuller (Orbital ATK), Mark Tobias (Northrup Grumman Innovation Systems) Presentation: David Griffin - Wednesday, March 6th, 10:10 AM - Madison
        A human mission to the moon and Mars is the stated space exploration goal of the United States and the international community. To achieve these goals, NASA is developing the Space Launch System (SLS) and the Orion crew capsule as key elements in the architecture for missions to the moon and Mars. As part of the SLS Booster Obsolescence and Life Extension (BOLE) program, Northrop Grumman Innovation Systems is working to address booster obsolescence issues in design and manufacturing. The upgraded boosters will also provide increased performance that will benefit future lunar campaigns, science missions, and the eventual Mars campaign.
    • 08.03 Advanced Launch Vehicle Systems and Technologies Jon Holladay (NASA) & Melissa Sampson (Ball Aerospace)
      • 08.0303 SLS with Kick Stages for Outer Planet Science Missions Terry Haws (Northrop Grumman Corporation), Mike Fuller (Orbital ATK) Presentation: Terry Haws - Thursday, March 7th, 04:30 PM - Gallatin
        This paper discusses the capability of NASA's SLS (Space Launch System), both alone and with kick stages, to deliver payloads for outer planet science missions. There are currently a number of solid motors that could be used as kick stages, and this paper analyzes the results, advantages, and disadvantages of using these motors along with SLS to deliver larger payloads with shorter mission times.
      • 08.0305 A Spatial Perspective on the Metallized Combustion Aspect of Rockets Mohammed Abrar Nizami (GATE PATHSHALA EDUCATIONAL SERVICES LLP.), Aditya Virkar (SRM Institute of Science & Technology), Chitresh Prasad (SRM Institute of Science & Technology), Arvind Ramesh (SRM Institite of Science & Technology), Vinayak Malhotra (SRM University), Karan Dholkaria (SRM Institute of Science & Technology) Presentation: Mohammed Abrar Nizami - Thursday, March 7th, 04:55 PM - Gallatin
        I am CEO & Founder of Gate Pathshala Educational Services LLp located in Chennai, India. It is an institute where we teach several subject of Aerospace engineering. After finishing my masters in aerospace Engineering from IIT Madras, India, I worked CAE Simulation Technologies on electro-mechanical systems of aircrafts namely Fuel system, Flight controls, and smoke detection system etc. Currently i am teaching students at gate pathshala aerodynamics and aircraft performance. My major area of research is Aerodynamics and parallelly I have been busy in developing a code for meshfree cfd using Smoothed particle hydrodynamic techniques. Today I am here to present the research work done by me and my students with title A spatial Perspective on metallized combustion of rockets.
    • 08.04 Human Factors & Performance Jessica Marquez (NASA Ames Research Center) & Kevin Duda (The Charles Stark Draper Laboratory, Inc.)
      • 08.04 8.04 Keynote: Spacesuits of the Future: Intersections of Science Fact and Science Fiction Bonnie Dunbar Presentation: Bonnie Dunbar - - Gallatin
        The challenge for protecting humans from extreme environments has been a test of engineering ingenuity for hundreds of years. From deep sea diving to high altitude flight, the design goals have been fairly straight forward: Firstly, keep the human alive, and Secondly, to allow them to operative effectively in the environment. As we move into space, it is more important than ever that we not only design "spacesuits" to keep the human alive, but also to design them to be more operationally transparent. Where are we now, and where do we need to be in the 21st Century?
      • 08.0401 Do Workload and Sensory Modality Predict Pilots’ Localization Accuracy? Christopher Brill (U.S. Air Force Research Laboratory), Anthony Gibson (Air Force Research Laboratory), Ben Lawson (U.S. Army Aeromedical Research Laboratory), Angus Rupert () Presentation: Christopher Brill - Thursday, March 7th, 09:20 AM - Gallatin
        Situation awareness (SA) decrements remain a safety issue for aviation, as reduced SA has been found to contribute to spatial disorientation (SD). SD has been linked consistently to aviation mishaps, costing aircrew lives, material assets, and millions of dollars. Prior research has focused on improving SA through multisensory cueing. Investigations on spatial cueing have evaluated differences in localization accuracy as a function of sensory modality (e.g., 3-D audio, tactile; Brill, Lawson, & Rupert, 2015; Brill, Rupert, & Lawson, 2015; Cholewiak, Brill, & Schwab, 2004). The current paper expands on previous findings by investigating whether subjective performance correlates with objective behavioral performance data. Implications for these findings include pilots’ ability to monitor performance and whether these relationships hold across cue modalities. The findings should be considered when developing cues for displaying information in future systems.
      • 08.0402 Enabling Communication between Astronauts and Ground Teams for Space Exploration Missions Jessica Marquez (NASA Ames Research Center), Steven Hillenius (NASA), Jimin Zheng (NASA - Ames Research Center), Ivonne Deliz (ASRC/NASA Ames Research Center), Bob Kanefsky (), Jack Gale (NASA - Ames Research Center) Presentation: Jimin Zheng - Thursday, March 7th, 09:45 AM - Gallatin
        Over the last four years, Playbook’s Mission Log has evolved to become an enabling capability for analog missions that simulate deep space, exploration missions with communication transmission latency. Playbook is a planning and execution web-application for mission operations, aggregating multiple sources of information for astronauts to execute the mission in one place: timeline, procedures, chat interface. Playbook’s Mission Log provides a multimedia chat software interface with unique features and functionalities that support asynchronous communication between analog astronauts and ground support teams. This paper describes the iterative design the Mission Log has undergone based on user observations and solicited feedback. Key features include indicators that help users cope with asynchronous communication as well as aids that assist teams coordinate work. Future work and capabilities are outlined, which build upon the increased use of the Mission Log as a communication and coordination tool for space exploration.
      • 08.0403 Comparison of Photogrammetric and Laser Hand Scans to Manual Measurements for EVA Glove Fabrication Bonnie Dunbar (Texas A&M University), Patrick Chapates (Texas A&M University) Presentation: Bonnie Dunbar - Thursday, March 7th, 10:10 AM - Gallatin
        Spacesuits are critical to human survival and exploration outside of the Earth’s protective environment. A number of environmental variables must be considered when designing a protective suit, which vary by location: Low Earth Orbit (LEO), Lunar Surface, or Mars Surface. Common to all the environments is the importance of a well-fitting suit, including gloves, in order to effectively and safely conduct EVA operations. During the Mercury, Gemini, Apollo, and Skylab programs, astronauts wore customized pressure suits and gloves. During the Shuttle era, astronauts were allocated to one of five general suit sizes: XS, S, M, L, and XL which were eventually reduced to 2 or 3 sizes. Shuttle EVA gloves varied between re-flight of standard sizes, to customized gloves. In spite of the customization of current EVA gloves, astronauts on the International Space Station (ISS) can experiencing strength degradation of over 50%, and many are experiencing finger injuries, including the loss of fingernails. The lack of significant performance improvement with current customization is confounding and the cause of the injuries are still largely unknown. Our objective is perform research to better understand the current “Fit” problems, which we believe will lead to customized suits and gloves designed to improve overall performance: enhance dexterity, reduce strength requirements, and minimize fatigue while still satisfying both thermal and micro-meteoroid requirements. Although many industries (e.g. aeronautics, automobile and apparel) are moving towards Digital Human Modelling (DHM) in order to design and fabricate with Finite Element Analyses (FEA), customization of current Phase VI gloves still generally begins with a manual measurement of each crew member’s hands in accordance with NASA Human Factor’s standards, followed by a mold casting which is scanned and measured. Manufacture of each glove is labor intensive. As far as the authors can determine, no dynamic digital analyses has been made of different hand configurations to characterize changes in measurements in order to design a glove with optimized fit from finger extension to tool grasp. In order to accomplish a future vision of scanning a hand in motion followed by rapid prototyping of a functionally optimized EVA glove, the Texas A&M University (TAMU) Aerospace Human Systems Laboratory (AHSL) recently acquired a 3dMD 3D Motion Capture system configured to capture 20 seconds of hand motion or 200 frames. While the final goal will be to develop digital scans which can be converted to FEA models, complete with skin properties, the objective of this paper is to report the results of comparing manual anthropometric hand measurements with those produced through the digital imaging of the 3dMD system and the results of converting the digital file into a 3D printed hand which replicates both the manual and 3dMD measurements. We are also exploring digital images with the Vitus Laser System. Initial results indicate that motion capture digital images may be used to accurately determine dimensional changes in a hand which provides a positive step towards DHM of the hand/EVA glove combination.
      • 08.0408 Human-Machine Interactions in Apollo and Lessons Learned for Living off the Land on Mars George Lordos (Massachusetts Institute of Technology), Sarah Summers (United States Air Force), Jeffrey Hoffman (Massachusetts Institute of Technology), Olivier De Weck (Space Systems Laboratory) Presentation: George Lordos - Thursday, March 7th, 10:35 AM - Gallatin
        Human-machine interactions underpinned the resilience of Project Apollo to unplanned disturbances and were a critical factor in its success. We briefly describe 19 Apollo-era case studies in human-machine interactions involving unplanned disturbances from the vantage points of four stages of the system lifecycle: conceive, design, implement and operate. Using the System Theoretic Process Analysis (STPA) diagrams on a representative selection of these cases, we explore how emergent system behavior in Apollo was constrained within boundaries consistent with mission success, and we abstract and generalize a key lesson learnt from each lifecycle stage. These were: (1) Human and machine shall each do what they are best at (2) clarity in the placement of the human-machine boundary enables realization of synergies from their interaction (3) concurrent optimization and testing of functions of humans and machines contributes to successful validation of complex system implementation (4) the costly development of trust between humans and machines underpins operational resilience in the face of internal and external disturbances. We then adapt and apply these lessons to the conceptual design process for future human-robot teams tasked with in-situ resource utilization (ISRU) on the Moon or Mars. We find that these Apollo learnings are transferable to Moon and Mars ISRU human-robot interactions, because the objective of ‘living off the land’ on other worlds will be as new, as unproven, as mission-critical, and as difficult as safely landing humans on the Moon and returning them to Earth was in 1969. We also show that these learnings from Apollo are especially impactful if applied at the earliest stages of a complex system lifecycle, i.e. during the ideation of concept fragments for the future human exploration of Mars. These methods may be applied to systematically extract and transfer best practices in human-machine interaction between superficially dissimilar mission architectures.
    • 08.05 Space Human Physiology and Countermeasures Andrew Abercromby (NASA Johnson Space Center) & Ana Diaz Artiles (Texas A&M University)
      • 08.0501 Human Physiology and Countermeasures for Spaceflight from the Perspective of an ISS Astronaut Steve Swanson (Boise State University) Presentation: Steve Swanson - Thursday, March 7th, 11:00 AM - Gallatin
        This paper will discuss physiological changes experienced by the author during long-duration spaceflight on the International Space Station. Changes not only from microgravity, but also possibly from other sources on the ISS. And correspondingly, discuss how well the countermeasures worked for him and discuss the issues he had using these countermeasures and areas these countermeasures were deficient, such as core strength.
    • 08.06 Mechanical Systems, Design and Technologies Lisa May (Murphian Consulting LLC) & Alexander Eremenko (Jet Propulsion Laboratory)
      • 08.0601 Mechanical Design and Configuration of Penetrations for the Europa Clipper Avionics Vault Structure Nicholas Keyawa (Jet Propulsion Laboratory), Ali Bahraman (JPL), William Hatch (Jet Propulsion Laboratory), Katherine Dang (Jet Propulsion Laboratory), Lou Giersch (NASA Jet Propulsion Lab) Presentation: Nicholas Keyawa - Sunday, March 3th, 04:30 PM - Gallatin
        The main purpose of the Avionics Vault is to shield radiation sensitive electronics for the Europa Clipper Spacecraft. The vault is a box structure made out of aluminum panels. The panels are roughly 10 mm thick in order to shield the electronics from the orbital total ionizing radiation around Jupiter. The vault requires an electromagnetic interference (EMI) shielding effectiveness (SE) of at least 70 dB in order to mitigate EMI with the spacecraft radar receiver. Overall, the vault accommodates four main types of penetrations: receptacle connectors, pass-through cables, fluid lines, and vent holes. More than 150 cables penetrate the vault panels to connect to electronic boxes inside. Fluid pipes enter and exit the vault to transfer heat to the rest of the spacecraft. Vent holes provide a path for air to escape from the vault during launch. Several novel penetrations designs were created to meet EMI and radiation shielding requirements. Receptacle connectors interface to the vault panels using 1.3 mm thick Ta10W plates. Pass-through cables penetrate the vault using aluminum clamshells after being wrapped with Teflon cushion tape, Kapton tape, and copper tape. Vent hole penetrations consist of a copper mesh for EMI shielding and an aluminum radiation shield bracket to direct air out of the vault during launch. Fluid lines terminate at the vault wall using mechanical fittings that resemble a nut and bolt interface. In addition, most mechanical seams and penetrations utilize EMI gaskets to ensure proper EMI shielding. To reduce risk and confirm that the vault penetration designs were appropriate for EMI shielding, an EMI chamber at the Jet Propulsion Laboratory (JPL) was used to test a mock-up vault panel with multiple variations of all four types of vault penetrations. This EMI SE test also incorporated different methods for bundling pass-through cables, and a comparison of flange mounted connectors versus jam nut connectors. A low noise preamplifier and a Rohde & Schwarz spectrum analyzer measured E-field levels transmitting through the mock-up vault panel. The results showed a shielding effectiveness of 77 dB for the mock-up vault panel, which exceeds the 70 dB target for Europa Clipper. Both the flange mounted connectors and jam nut connectors exhibited similar EMI SE results at the measured frequencies, and all variations of vault penetrations showed favorable EMI SE levels. Since the flight panels will be much larger and include many more penetrations, there will be testing of the flight vault to confirm its EMI SE is compliant with environmental requirements.
      • 08.0602 Solar Radiation Disturbance Torque Reduction for the Parker Solar Probe Observatory Juan Ruiz (Johns Hopkins University/Applied Physics Laboratory), Daniel Kelly (Johns Hopkins University/Applied Physics Laboratory), David Napolillo (Johns Hopkins University/Applied Physics Laboratory) Presentation: Juan Ruiz - Sunday, March 3th, 04:55 PM - Gallatin
        We present the methodology used for reducing solar pressure disturbance torques for the Parker Solar Probe (PSP) Observatory by minimizing the offset between spacecraft’s Center of Gravity (CG) and Center of Pressure (CP). The force due to solar radiation pressures encountered by the PSP spacecraft, particularly at the 9.86 solar-radii (Rs) closest approach point in the orbit, are of a sufficient magnitude to produce significant disturbance torques. Inside of 0.25 AU, the Observatory is required to keep its Thermal Protection System (TPS) pointed precisely towards the Sun in order to ensure the survivability of the observatory. It was crucial to reduce disturbance torques encountered during this phase of flight to a low enough level such that the guidance and control system of the spacecraft would be able to control attitude without requiring excessive or untimely propellant usage. We present the process used for proactively packaging a balanced spacecraft and analytically determining the spacecraft’s mass properties throughout the entirety of the mission, including associated CG and inertia tensor changes due to propellant usage and movement of deployable hardware and mechanisms. We also present the process used for deriving the spacecraft’s CP based on the geometry and optical properties of the hardware exposed to the full solar environment, as well as its shift due to degradation of those properties throughout the life of the mission. Using both of those data sets, we present the approach used to install ballast masses on the observatory in order to minimize the offset, as well as data collected during spacecraft mass properties testing concluded towards the end of PSP’s assembly, test, and launch operations campaign. Finally, we present test correlated center of gravity and center of pressure data, and examine expected effects for the duration of the Parker Solar Probe mission.
      • 08.0606 Geometry and Joint Systems for Lattice-Based Reconfigurable Space Structures Megan Ochalek (Massachusetts Institute of Technology), Kenneth Cheung (NASA - Ames Research Center), Greenfield Trinh (NASA - Ames Research Center), Olivia Formoso (NASA - Ames Research Center), Benjamin Jenett (), Christine Gregg (NASA Ames Research Center) Presentation: Megan Ochalek - Sunday, March 3th, 05:20 PM - Gallatin
        This paper discusses the analytic methods for the design of the discrete elements of ultralight lattice structures. This modular, building block strategy allows for relatively simple element manufacturing, as well as relatively simple robotic assembly of low mass density structures on orbit, with potential for disassembly and reassembly into highly varying and large structures. This method also results in a structure that is easily navigable by relatively small mobile robots. Geometry choice affects the final system's mechanical properties, manufacturability of the components, and automated robotic constructibility of a complete system.
      • 08.0608 Membrane Deployment Technology Development at DLR for Solar Sails and Large-Scale Photovoltaics Tom Sproewitz (German Aerospace Center), Patric Seefeldt (German Aerospace Center - DLR), Jan Thimo Grundmann (DLR German Aerospace Center), Peter Spietz (DLR German Aerospace), Rico Jahnke (), Eugen Mikulz (), Thomas Renger (German Aerospace Center - DLR), Siebo Reershemius (German Aerospace Center - DLR), Kaname Sasaki (German Aerospace Center - DLR), Maciej Sznajder (German Aerospace Center - DLR), Norbert Toth (German Aerospace Center - DLR) Presentation: Tom Sproewitz - Sunday, March 3th, 09:00 PM - Gallatin
        Following the highly successful flight of the first interplanetary solar sail, JAXA’s IKAROS, with missions to come such as NASA’s NEASCOUT nanospacecraft solar sail and JAXA’s Solar Power Sail ( a solar-electric propelled mission to a Jupiter Trojan asteroid), and on the back-ground of the ever increasing power demand of GEO satellites now including all-electric spacecraft, there is renewed interest in large lightweight structures in space. Among these, deployable membrane or ‘gossamer’ structures can provide very large functional areas for innovative space applications which can be stowed into limited volumes of launch vehicle fairings as well as secondary payload launch slots, depending on the scale of the mission. Large area structures such as solar sails or high-power photovoltaic generators require a technology that allows their controlled and thereby safe deployment. Before using such technology for a dedicated science or commercial mission, it is necessary to demonstrate its reliability, i.e., TRL 6 or higher. A reliable technology that enables controlled deployment was developed in the GOSSAMER-1 solar sail project of the German Aerospace Center. It included the verification of its functionality with various laboratory tests to qualify the hardware for a first demonstration in low Earth orbit. We provide an overview of the GOSSAMER-1 hardware development and qualification campaign. The design is based on a crossed boom configuration with triangular sail segments. Using engineering models, all aspects of the deployment were tested under ambient environment. Several components were also subjected to environmental qualification testing. An innovative stowing and deployment strategy for a controlled deployment and the required mechanisms has been worked out. The tests conducted provide allow a mechanical characterization of this process, in particular the measurement of the deployment forces. The stowing and deployment strategy was verified by tests with an engineering qualification model of one (out of four) GOSSAMER-1 deployment units. According to a test-as-you-fly approach the tests included vibration testing, venting, thermal-vacuum testing and ambient deployment testing. In these tests the deployment strategy proved to be suitable as a controlled deployment for gossamer spacecraft. Deployments on system level were demonstrated to be robust and controllable. The GOSSAMER-1 solar sail membranes were also equipped with small thin-film photovoltaic arrays intended to supply the core spacecraft. In our follow-on project GOSOLAR, the focus is now entirely on deployment systems for huge thin-film photovoltaic arrays. Based on the GOSSAMER-1 experience, deployment technology and qualification strategies, new technologies for the integration of thin-film photovoltaics are being developed and qualified for a first in-orbit technology demonstration within five years. Main objective is the further development of a deployment technology for a 25 m² gossamer solar power generator and a flexible photovoltaic membrane. GOSOLAR enables a wider range of deployment concepts beyond solar sail optimized methods. It uses the S2TEP bus system developed at the Institute of Space Systems as part of the DLR satellite roadmap.
      • 08.0609 HP3 Instrument Support System Structure Development for the NASA/JPL Mars Mission InSight Tom Sproewitz (German Aerospace Center), Siebo Reershemius (German Aerospace Center - DLR), Kaname Sasaki (German Aerospace Center - DLR), Marco Scharringhausen (German Aerospace Center - DLR) Presentation: Tom Sproewitz - Sunday, March 3th, 09:25 PM - Gallatin
        On May 05, 2018 NASA JPL launched its mission to Mars called “InSight”. Main objective of this mission is to gain more knowledge about the evolution of terrestrial planets and to more precisely determine properties of core, mantle and crust of Mars. One of a number of different scientific instruments onboard the lander there will be HP3 (Heat Flow and Physical Properties Package), which was developed by the German Aerospace Center (DLR). It will be operated on Martian ground to measure the heat flow through the Martian outer crust. It uses a hammering mechanism which will pull a tether approx. 5 m into the soil. The hammering device is equipped with foil heaters on the outer hull and the tether is equipped with temperature elements. Both is needed for the determination of the thermal conductivity of the surrounding regolith and the measurement of the temperature gradients in the ground. There is the need of a separate system to be able to perform those activities on the surface. This system is called the “HP3 Support System”. Its main task is to ensure a stable, nearly perpendicular position of the hammering mechanism relative to the soil on the Martian surface before initial penetration. It furthermore houses the instruments for length measurement and serves as electrical connection to the lander. The paper will give an overview of the development and the qualification of the structure of the Support System. It will focus on the mechanical design, the analysis of the structural dynamics but in particular on the testing which includes standard environmental testing but also numerous development tests that are very mission specific. The mechanical design of the Support System is mainly driven by a unique set of requirements derived from the working environment on Mars, the deployment from the lander deck and the mechanically separated operation on the surface. The instrument design will be explained to show, which design elements were implemented to ensure proper functionality. Various development tests had to be performed during the Support System structure development. Besides the standard qualification tests, special tests were developed to show compliance of the instrument design to the requirements. Such tests are: Separation Tests from the lander deck in cold environment under various tilt angles, Tether Deployment Tests, under various temperatures, foldings and routings, Feet Sliding Resistance Tests on sand with different slopes. The paper will give an overview on all tests necessary for the support system qualification and will describe test setups and the results.
      • 08.0610 IRESA - Intelligent Redundant Spacecraft Actuator Florian Schummer (Technical University of Munich), Robin Roj (Forschungsgemeinschaft Werkzeuge und Werkstoffe Remscheid e.V.), Alexander Czechowicz (Kunststoffverarbeitung Hoffmann GmbH), Jakob Bachler (Technical University of Munich), Martin Langer (Technical University of Munich), Tejas Kale (Technical University of Munich), Rupert Amann (Technical University of Munich), Sven Langbein (Forschungsgemeinschaft Werkzeuge und Werkstoffe Remscheid e.V.), Peter Dueltgen (Forschungsgemeinschaft Werkzeuge und Werkstoffe Remscheid e.V.) Presentation: Florian Schummer - Sunday, March 3th, 09:50 PM - Gallatin
        IRESA is the acronym for the intelligent redundant spacecraft actuator. Based on shape memory alloys, the actuator is designed for rotational as well as small translational movements. The presentation covers the basics of designing with shape memory alloys, an explanation of the actuator's design and test results and lessons learned during testing. After providing the draft for a fatigue detection method enabling predictive maintenance, the presentation is concluded with the first drafts for the second generation of the actuator.
    • 08.07 Spacecraft Propulsion and Power Systems Erica Deionno (The Aerospace Corporation) & John Brophy (Jet Propulsion Laboratory)
      • 08.0705 GoSolAr - DLR's Gossamer Solar Array Concept Using Flexible Thinfilm Photovoltaics Tom Sproewitz (German Aerospace Center), Jan Thimo Grundmann (DLR German Aerospace Center), Patric Seefeldt (German Aerospace Center - DLR), Hauke Martens (German Aerospace Center - DLR), Siebo Reershemius (German Aerospace Center - DLR), Nies Reininghaus (German Aerospace Center - DLR), Kaname Sasaki (German Aerospace Center - DLR), Peter Spietz (DLR German Aerospace), Maciej Sznajder (German Aerospace Center - DLR), Norbert Toth (German Aerospace Center - DLR) Presentation: Tom Sproewitz - Tuesday, March 5th, 10:35 AM - Dunraven
        The power demand for future satellite applications will continue to rise. Geostationary telecom-munication satellites currently approach a power level of up to 20 kW. Future spacecraft will provide yet more transponders and/or direct mobile-satellite services. Electric propulsion is in-creasingly used for station keeping, attitude control and GEO circularization. Interplanetary mis-sions already use kW-range electric propulsion. Space Tugs are studied for several fields. Suitable engines require 100 kW or more. The envisaged use of such engines and the operation of future GEO satellites lead to a renewed interest in large, deployable and ultra-lightweight power gen-erators in space. Within the GoSolAr (Gossamer Solar Array) activity, DLR develops a new photovoltaic array technology for power generation. It is based on the DLR Gossamer approach using lightweight, deployable CFRP booms and a polymer membrane covered with thin-film CIGS photovoltaics. The booms are arranged in a crossed configuration with a central deployment unit. The photovol-taic area is composed of one large square membrane with double folding using two-dimensional deployment. Even though the efficiency of thin-film photovoltaics is currently only about 1/3 of that of con-ventional photovoltaics, a membrane based array can already achieve better mass/power ratios. A 50 kW array requires an area of approximately 20 m x 20 m. In a first step, DLR develops a fully functional 5 m x 5 m demonstrator partially covered with thin-film photovoltaics, using the DLR small satellite platform S2TEP. Space compatible thin-film photovoltaics need to be select-ed and tested. They are integrated on standardized generator modules that will be assembled into a large, foldable and deployable membrane. A controlled deployment of structure and membrane, and a sufficiently stiff support structure for operation are key development topics. We present the conceptual design of the GoSolAr demonstrator, the main requirements, prelimi-nary technical budgets and the development strategy. An overview will be given on the selection and the maturity of the key technologies and subsystems, such as deployable membrane with in-tegrated photovoltaic generators; deployable CFRP booms including deployment mechanisms; photovoltaic cell selection and integration to generator units; the array harness concept as well as the electronics concept, for operation and photovoltaics characterization. Furthermore, an over-view of the first manufactured breadboard models and their testing will be presented, e.g. com-bined testing of booms and mechanically representative generator arrays to evaluate deployment and interface forces for the preliminary design.
      • 08.0711 Infrared Nanoantenna-Coupled Rectenna for Energy Harvesting Joshua Shank (Sandia National Laboratories), Paul Davids (Sandia National Laboratories), David Peters (Sandia National Laboratories) Presentation: Joshua Shank - Tuesday, March 5th, 11:00 AM - Dunraven
        We will present a new energy harvesting device, called a rectenna, designed to operate with low-temperature heat sources. The rectenna operates from radiated power, rather than direct contact, allowing for the design of a mechanically robust system. Furthermore, the device fabrication uses standard CMOS processes allowing for reliable large area manufacturing. We will discuss the rectenna's physics of operation, design, and optimization.
    • 08.08 Nuclear Space Power Generation June Zakrajsek (NASA - Glenn Research Center) & David Woerner (Jet Propulsion Laboratory)
      • 08.0801 Americium Oxide Surrogate Studies: Pursuing the European Radioisotope Power Systems Fuel Form Emily Jane Watkinson (University of Leicester), Richard Ambrosi (University of Leicester), Daniel Freis (European Commission - JRC), Jean Francois Vigier (), Tim Tinsley (National Nuclear Laboratory), Mark Sarsfield (National Nuclear Laboartory), Keith Stephenson (European Space Agency), Jens Najorka (Natural History Museum) Presentation: Emily Jane Watkinson - Monday, March 4th, 08:55 AM - Dunraven
        The European Space Agency funded programme into the research and development of European radioisotope power systems (RPSs) began in 2008. Three RPS technologies are under development, namely, radioisotope heater units, radioisotope thermoelectric generators, and Stirling generators. Americium (241Am) was selected as the ‘fuel’, which provides radiogenic heat to the RPSs. An essential aspect of the programme is the ability to create an americium oxide fuel form, namely discs or pellets, that meet a range of requirements e.g. intact bodies with relatively high relative densities that allow for He-outgassing. Research with surrogates for americium oxides is essential for investigating the range of variables that influence the ability to achieve this whilst limiting the research with the highly radioactive material. In this study, americium oxide surrogates (e.g. Nd2O3) have been created using two different techniques (continuous oxalate precipitation and calcination, and sol-gel and calcination) with the objective of creating particles with differing morphology. Owing to the polymorphism of Nd2O3, X-ray diffraction is conducted to assess crystal structure phase changes in the powder material to inform sintering studies. The surrogate powders are cold-pressed and sintered to assess the impact on pellet properties e.g. density and integrity. The surrogate fuel study highlights the importance of assessing the impact of particle shape and crystal structure on the ability to meet fuel form requirements, and will inform future research with the americium oxide fuel.
      • 08.0802 Progress and Future Roadmap on 241Am Production for Use in Radioisotope Power Systems Tim Tinsley (National Nuclear Laboratory), Richard Ambrosi (University of Leicester), Keith Stephenson (European Space Agency), Mark Sarsfield (National Nuclear Laboartory) Presentation: Richard Ambrosi - Monday, March 4th, 09:20 AM - Dunraven
        Provision of RPSs to future missions would bring significant benefit to the range of science in space exploration that is able to be achieved. The paper will outline the reasons behind thechoice of 241Am, the development work that has taken place so far, and the expected route forward towards a flight ready system.
      • 08.0803 Stirling Convertor Based 50-500W Radioisotope Power System Generator Study Joseph Vander Veer (Teledyne Energy Systems), Robert Sievers (Teledyne Energy Systems) Presentation: Joseph Vander Veer - Monday, March 4th, 11:00 AM - Dunraven
        Free piston Stirling convertor based generators present a significant advantage over traditional radioisotope power systems (radioisotope thermoelectric generators), which is conversion efficiency. Several configurations are considered ranging from ~50 We to ~500 We. Current dynamic systems have yet to prove themselves with respect to reliability. Therefore, a significant portion of the analysis focuses on reliability of the configurations. As dynamic convertor reliability has yet to be determined generator reliability studies are relative to convertor reliability. Reliability studies include the system controller, individual convertor controllers, and convertor redundancy. In addition to reliability: power, thermal efficiency, conversion efficiency, and weight are considered. Investigated configurations show system level efficiencies as high as 24% are possible.
      • 08.0805 Design and Development of the ESA Am-Fuelled Radioisotope Power Systems Alessandra Barco (University of Leicester), Richard Ambrosi (University of Leicester), Hugo Williams (University of Leicester), Tony Crawford (University of Leicester), Ramy Mesalam (The University of Leicester), Christopher Bicknell (University of Leicester Space Research Centre), Emily Jane Watkinson (University of Leicester), Keith Stephenson (European Space Agency), Alexander Godfrey (Lockheed Martin UK - Ampthill), Colin Stroud (lockheed martin uk ampthill), Marie Claire Perkinson (Airbus), Christopher Burgess (Airbus), Tim Tinsley (National Nuclear Laboratory) Presentation: Alessandra Barco - Monday, March 4th, 09:45 AM - Dunraven
        Radioisotope heater units (RHU) and radioisotope thermoelectric generators (RTG) are currently being developed for the ESA radioisotope power system program. The state-of-the-art for the USA and Russian systems is to use plutonium-238 as the radioisotope fuel; however, for the ESA applications americium-241 has been selected, due to its availability and relatively cost-effective production in the European context. The proposed designs implement a multi-layer containment approach for safety reasons, with a platinum-rhodium alloy for the inner containment of the fuel and carbon-based materials for the outer layers. The Am-fueled RHU provides 3 W of thermal power, and makes this design competitive with existing models in relation to specific power. The heat source for the RTG has a 6-side polygonal shape, with a distributed 3-fuel pellet architecture: this configuration allows to maximize the specific power of the RTG, since Am-based fuels have a lower power density than Pu-based fuels. The heat supplied by the fuel is 200 W, with an expected electrical power output of 10 W provided by six Bi-Te thermoelectric modules. Finite element structural and thermal analyses have been performed to assess the theoretical feasibility of the components as initially conceived. Mechanical and electrically-heated prototypes for the systems have already been tested in a representative lab environment at the University of Leicester; these tests have provided initial estimates for the efficiency of the systems. Both the RHU and RTG architectures are currently undergoing a new design iteration process. This presentation reports on the overall architecture and design of the Am-fueled RTG and RHU, the modelling results and the experimental data obtained so far.
      • 08.0806 Effect of Martian and Titan Atmospheres on Carbon Components in the General Purpose Heat Source Chris Whiting (University of Dayton), Chadwick Barklay (University of Dayton Research Institute) Presentation: Chris Whiting - Monday, March 4th, 11:25 AM - Dunraven
        Radioisotope power systems (RPS) that are currently in use today are designed with a closed fuel cavity. Multiple proposed designs for future RPS have included the use of an open fuel cavity, which indicates that the fuel, and its associated hardware, will be exposed to gases that could be found outside the generator. Most missions that would utilize an RPS will take place in the vacuum of space, and for those missions the choice of an open or closed fuel cavity is inconsequential. A few missions, however, could take place at a site that has an atmosphere, such as Mars or Titan. In these cases, it is important to understand how the extraterrestrial atmosphere of these locations could impact the components within the RPS. This knowledge will then help RPS designs make informed decisions regarding the choice of an open or closed fuel cavity. One of the most important components within the fuel cavity in an RPS is the general purpose heat source (GPHS) module. The GPHS plays critical thermal, structural, and safety based roles within the RPS. In this paper, we will examine the potential impact of a Martian or Titan atmosphere on the GPHS in the fuel cavity. First, thermodynamic chemical modeling studies were performed. These studies indicated that nearly all of the Martian atmosphere would be able to react with and erode the GPHS carbon. Considering the very low pressure of the Martian atmosphere, however, it is recommended that reaction rate studies are performed on GPHS carbon to determine if the erosion will be significant over the life of the RPS. Modeling studies of Titan indicated that there are no predicted chemical reactions between the Titan atmosphere and the GPHS. It was noted, however, that components of the Titan atmosphere could decompose to form solid carbon and ammonia. While these products are not expected to be a problem for the GPHS, which is the focus of this study, they could create significant issues for other materials in the RPS. It is therefore recommended that any open fuel cavity designs consider the impact that solid carbon and ammonia could have on the whole RPS. Initial reaction rate studies were performed between a simulated Martian atmosphere and a carbon-carbon composite material that is a surrogate for GPHS carbon. It was interesting to note that there was no measurable erosion in the sample after 72 h at 700 oC. While this preliminary result is encouraging, it is not possible to provide a recommendation at this point regarding the use of an open fuel cavity on Mars. Additional studies will be required to evaluate the degree of erosion over much longer times and much higher temperatures. In addition to studying the erosion of the GPHS carbon, it is recommended that future studies also investigate changes in other GPHS carbon properties, including thermal conductivity and mechanical strength.
      • 08.0807 Nuclear Considerations for the Application of Lanthanum Telluride in Future RPS Systems Michael Smith (Oak Ridge National Laboratory), Chadwick Barklay (University of Dayton Research Institute), Chris Whiting (University of Dayton) Presentation: Michael Smith - Tuesday, March 5th, 09:45 AM - Dunraven
        This talk will present the software tools, analysis methodology, and results from an investigation into the potential for nuclear transmutation of thermoelectric materials in radioisotope power systems (RPS). Discussion of potential future investigations involving RPS nuclear/chemical analyses will also be presented with a focus on radiation-induced degradation channels of concern that may be caused by plutonium oxide fuels.
      • 08.0809 Safety Studies for the ESA Space Nuclear Power Systems: Accident Modelling and Analysis Alessandra Barco (University of Leicester), Richard Ambrosi (University of Leicester), Keith Stephenson (European Space Agency) Presentation: Alessandra Barco - Monday, March 4th, 10:10 AM - Dunraven
        Within the framework of the ESA radioisotope power system (RPS) program, the University of Leicester is currently developing radioisotope heater unit (RHU) and radioisotope thermoelectric generator (RTG) systems for future space missions, with americium-241 as radioactive fuel. An important aspect of a nuclear material-based program is safety: in space applications, this involves ensuring that the design of RHU and RTG systems, in particular of the heat source (i.e. fuel and containment layers), meets a set of stringent requirements. It is therefore fundamental to properly design both the RTG and RHU in order to minimize the probability of radioactive material release into the environment in the event of an accident. The inner containment, or cladding, made of a platinum-rhodium alloy, is the first line of defense surrounding the americium-based fuel; additional layers of carbon-based insulators and carbon-carbon composites for the aeroshell ensure that the heat source can survive all possible accident conditions, from launch failures to Earth re-entry. Validated heat source accident models are necessary to inform the design iteration of the RHU and RTG heat sources, and to construct a safety case for their launch. The activity here presented is performed in collaboration with ArianeGroup in France and ESA/ESTEC. Its goal is to start the process of understanding the behavior of the fuel containment systems under the most relevant accident conditions by computer modelling, to validate them experimentally given the infrastructure, test means and expertise of ArianeGroup in this field, and to characterize the different materials at ESTEC. The data obtained will help to iterate and improve the design of the European RPS heat sources by focusing on the fuel containment.
      • 08.0811 Impedance Spectroscopy: A Tool for Assessing Thermoelectric Modules for Radioisotope Power Systems Ramy Mesalam (The University of Leicester), Hugo Williams (University of Leicester), Richard Ambrosi (University of Leicester), Daniel Kramer (University of Dayton Research Institute), Chadwick Barklay (University of Dayton Research Institute), Keith Stephenson (European Space Agency) Presentation: Ramy Mesalam - Tuesday, March 5th, 08:30 AM - Dunraven
        Thermoelectric energy convertors in the form of solid state modules are utilised in space nuclear power systems such as a radioisotope thermoelectric generator (RTG). However, to ensure that implemented thermoelectric modules are reliable, efficient, and capable of delivering power and energy over a required lifespan, Standardised, accurate and repeatable high-throughput measurement systems are needed. Recently, Impedance spectroscopy has shown promise as a tool to parametrically characterise thermoelectric modules with one simple measurement, showcasing itself as a potentially key enabling technology. This presentation showcases the use of impedance spectroscopy as a measurement system for assessing the health state of practical thermoelectric modules from batch production runs. Particularly for the case of candidate thermoelectric modules which are required to operate for long durations within an RTG system.
      • 08.0812 Radioisotope Power Systems for the European Space Nuclear Power Programme Richard Ambrosi (University of Leicester), Emily Jane Watkinson (University of Leicester), Ramy Mesalam (The University of Leicester), Alessandra Barco (University of Leicester), Christopher Bicknell (University of Leicester Space Research Centre), Tony Crawford (University of Leicester), Hugo Williams (University of Leicester), Marie Claire Perkinson (Airbus), Alexander Godfrey (Lockheed Martin UK - Ampthill), Colin Stroud (lockheed martin uk ampthill), Michael Reece (Queen Mary University London), Keith Stephenson (European Space Agency), Tim Tinsley (National Nuclear Laboratory) Presentation: Richard Ambrosi - Monday, March 4th, 08:30 AM - Dunraven
        Radioisotope thermoelectric generators (RTG) and heater units (RHU) systems are being developed in Europe as part of a European Space Agency (ESA) funded program. Aimed at enabling or significantly enhancing space science and exploration missions, these systems rely on the cost-effective production of americium-241 for the fuel. The use of an iterative approach and the application of lean methodologies for the development these systems have been the focus of this technology program. Isotope containment architectures and, in the case of RTG systems, bismuth telluride based thermoelectric generators are under development. At the small end of the scale, the RHU configuration is based on a 3 W thermal power output. The first version of this system has been designed and analysed. Electrically-heated and mechanical models have been produced and tested. The RTG heat source configuration is designed to deliver 200 W of thermal power output while minimizing the volume occupied by the fuel. A 5% total system conversion efficiency and a modular scalable design imply that electrical power output can range between 10 W and 50 W. Each RTG system could house up to 5 heat sources. An electrically-heated RTG system based on the 200 W heat source architecture has been designed, analysed and tested. The advancement in the design of the heat source for both RTGs and RHUs is currently the focus of the programme with the aim of advancing the technology readiness level of the containment structures. The most recent results of the programme will be presented.
      • 08.0813 Identifying and Mitigating Barriers to the Adoption of Advanced Radioisotope Power Systems Scott Brummel (), Mary Cummings () Presentation: Scott Brummel - Monday, March 4th, 10:35 AM - Dunraven
        Despite the significant research that is currently underway to mitigate inappropriate trust and risk perception for operators of complex systems, very little research is occurring to assess, describe, model, or develop risk mitigation strategies for engineers developing or applying new technologies. Here, we attempt to minimize this gap by defining and explaining factors contributing to inappropriate risk perception and resulting barriers for the adoption of Dynamic Radioisotope Power Systems (DRPS) for space exploration and offer up mitigations to these barriers.
      • 08.0814 Utilization of MMRTG’s "Waste Heat" to Increase Overall Thermal to Electrical Conversion Efficiency Daniel Kramer (University of Dayton Research Institute), Richard Ambrosi (University of Leicester) Presentation: Daniel Kramer - Tuesday, March 5th, 08:55 AM - Dunraven
        Since the launch of the first radioisotope power system (RPS) on Transit 4A in 1961, numerous research and development activities have been performed centered on increasing the overall thermal to electrical conversion efficiency of the selected nuclear fueled power system. The latest U.S. fielded RPS (MMRTG – Multi-Mission Radioisotope Thermoelectric Generator) contains eight GPHS (General Purpose Heat Source) modules which nominally yield ~2000WTh from the thirty-two 238PuO2 ceramic fuel pellets. MMRTG’s PbTe/TAGS-85 based thermoelectric couples have a thermal to electrical conversion efficiency of ~5.5% thus yielding ~110We at launch. This paper centers on the discussion of a conceptual idea that entails employing a second set of thermoelectrics on an MMRTG. These would be employed for possibly converting a portion of the excess “waste heat” (~1750 Wth) into additional electrical mission power. First-order experiments and calculations employing bismuth telluride (Bi2Te3) based thermoelectric modules being considered for a European RPS by the University of Leicester indicate that an improvement in the efficiency of an MMRTG could be achieved by integrating them with the PbTe/TAGS-85 thermoelectrics being utilized in the MMRTG in a “dual” or “cascaded” arrangement. This arrangement of two different integral thermoelectric materials suggests the intriguing possibility of the additional harvesting of a portion of the MMRTG’s currently unutilized “waste heat”. This appears to be feasible since the cold side temperature of the PbTe/TAGS-85 in an MMRTG is ~200oC which corresponds to typical hot-side operating temperatures of the Bi2Te3 thermoelectric modules. It is recognized that extensive thermo-mechanical-electrical design, modeling, and analysis are required to fully investigate the cascaded thermoelectric concept. In addition, materials compatibility and assembly aspects will need to be fully addressed in the future. The present work indicates that system-level performance gains could be achieved via a “cascaded” or cMMRTG which could result in electrical power increases at BOM (Beginning of Mission) of up to ~25%, and perhaps more significantly, gains in EODL (End of Design Life) power of up to ~40% which could be utilized on a future space mission.
      • 08.0815 Development of a High-Efficiency Cascaded Thermoelectric Radioisotope Power System Chadwick Barklay (University of Dayton Research Institute), Daniel Kramer (University of Dayton Research Institute), Richard Ambrosi (University of Leicester), Ramy Mesalam (The University of Leicester) Presentation: Chadwick Barklay - Tuesday, March 5th, 10:10 AM - Dunraven
        Since the 1960s there have been numerous development activities on high-impact material and device-level technologies that could be integrated into current or future radioisotope power systems (RPS) to enhance their performance. One recent concept study proposed cascading thermoelectrics to convert some of the waste heat from the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) into electrical power. The first-order evaluations of the concept study suggested that performance improvements to beginning-of-life (BOL) and end-of-design life (EODL) power could be achieved by integrating bismuth telluride (Bi2Te3) thermoelectric modules into the MMRTG design. This paper discusses a proof of concept development approach to determine the BOL and EODL performance gains that could potentially be obtained by employing Bi2Te3 thermoelectric modules in an RPS as a second stage in a cascaded architecture. The principal efforts embedded in this approach entail an iterative modeling and analytical process to arrive at a Stage 2 module design coupled with a heat rejection system design that enables the cascaded thermoelectric system to operate at satisfactory performance levels. This paper addresses some of the design considerations that will need to be addressed at the system level. For the purposes of this study the MMRTG characteristics and properties are employed as the basis for this paper
      • 08.0818 A Status Update on the eMMRTG Project Christopher Matthes (NASA Jet Propulsion Lab), David Woerner (Jet Propulsion Laboratory), Stan Pinkowski (NASA Jet Propulsion Lab) Presentation: Christopher Matthes - Tuesday, March 5th, 09:20 AM - Dunraven
        NASA has employed Radioisotope Thermoelectric Generators (RTGs) to power many missions throughout the past several decades. The Multi-Mission RTG (MMRTG) used on Mars Science Laboratory is the most recent generator developed, and the only spaceflight-qualified system currently available. The enhanced Multi-Mission RTG (eMMRTG) would be an upgrade of the MMRTG using the most current thermoelectric (TE) technology, and would provide the space community with a system that would have substantially higher end-of-design-life (EODL) power. The NASA RPS Program recently instantiated an eMMRTG system development project, evolving from an ongoing technology maturation effort at JPL to a project designed to mature and transition the skutterudite (SKD) TE couples and technology into an operational RTG. The project has made significant advances in maturing SKD technology for use in the eMMRTG, and is looking ahead to potential RTG system development. Mini-module and couple life tests have produced substantial performance data that has helped refine the couple design and support lifetime performance predictions. Additional strength and thermoelectric properties tests have been performed to verify the design specifications and robustness of the candidate TE couples. Replacing the current MMRTG couples with SKD also necessitates system design changes that must be well understood. Recent systems engineering studies have focused on minimizing risk associated with updating the flight-proven MMRTG design. Upgrading the module insulation has been shown to result in 98% lower levels of CH4/H2 outgassing products. Performance analysis has been completed using the most recent TE couple sizes in order to understand the maximum acceptable power degradation rate to achieve the required eMMRTG power of 77 W at EODL. This paper provides an update on recent SKD technology maturation efforts and the results of several systems engineering tasks that continue to pave the way for successful system development.
      • 08.0819 Small Stirling Technology Exploration Power for Future Space Science Missions Scott Wilson (NASA - Glenn Research Center) Presentation: Scott Wilson - Monday, March 4th, 11:50 AM - Dunraven
        High efficiency RPS could be used to increase science data return on future missions or could be mission enabling for low power applications. NASA GRC is developing low power dynamic RPS subsystems that would convert heat from multiple light weight radioisotope heater units to 1 watt of usable direct current electric power for spacecraft instrumentation and communication. The power system could be used to charge batteries or capacitors for higher power burst usage. A free-piston Stirling convertor and controller are being designed and fabricated by GRC for initial demonstration. Development also includes maturation of an efficient multi-layer metal insulation package. Proof-of-concept hardware is being prepared to demonstrate this new class of power conversion technology in a laboratory environment. This power system could be matured for small probes, landers, rovers and communication repeaters needed on future space exploration missions.
    • 08.09 Autonomy for Aerospace Applications Julia Badger (NASA - Johnson Space Center) & Ted Steiner (Draper)
      • 08.0902 Model-Based Approach to Rover Health Assessment - Mars Yard Discoveries Ksenia Kolcio Prather (Okean Solutions, Inc), Ryan Mackey (Jet Propulsion Laboratory), Lorraine Fesq (Jet Propulsion Laboratory) Presentation: Ksenia Kolcio Prather - Tuesday, March 5th, 08:30 AM - Cheyenne
        This paper presents the modeling process and test results of the Model-based Off-Nominal State Identification and Detection (MONSID) fault diagnosis system as applied to the mobility subsystem of JPL’s Athena development rover. Athena’s mobility system includes independent steering and driving motors for six wheels as well as wheel position sensors. The rover mobility system proved particularly challenging to model due to limited visibility into lower level wheel assembly hardware, a high degree of terrain interaction, and incomplete understanding of Athena behavior. However, even with simplified models, MONSID proved able to detect 16 distinct anomaly types during functional tests and simulated science activities carried out in JPL’s Mars Yard. These faults included simulated and actual motor faults as well as instances of stalls due to terrain. Additionally, several detected faults were discovered during MONSID testing that were not anticipated. System characterization during the modeling process revealed several hardware and operational problems, leading to updates in Athena’s control firmware and sensor processing software.
      • 08.0903 Silhouette-based 3D Shape Reconstruction of a Small Body from a Spacecraft Saptarshi Bandyopadhyay (Jet Propulsion Laboratory), Issa Nesnas (Jet Propulsion Laboratory), Benjamin Hockman (NASA Jet Propulsion Laboratory, California Institute of Technology), Benjamin Morrell (JPL), Shyam Bhaskaran (Jet Propulsion Laboratory) Presentation: Saptarshi Bandyopadhyay - Tuesday, March 5th, 08:55 AM - Cheyenne
        In this paper, we present a novel Shape from Sil- houette (SfS) algorithm to estimate the physical and dynamical properties of a small body—such as an asteroid or comet—from periodic images taken from a distant approaching spacecraft. Standard mapping techniques such as Stereo-Photo-Clinometry (SPC) and Stereo-Photo–Grammetry (SPG) are designed for close-proximity observations in which the body is 1000s of pixels in area, and there are enough surface features on the object. In contrast, our algorithms are suited for distant observations (i.e. during first approach) in which the body is only 10s–100s of pixels in area and does not present any useful visual features. First, using the Fast-Fourier-Transform of the light curve of the small body, we estimate its rotation rate. Then, using our novel silhouette-based 3D shape reconstruction technique, we estimate the shape and size of the small body and its pole of rotation. In this paper, we assume that the small body is performing pure rotation (no tumbling) about its principal axis, that the Sun is directly behind the spacecraft, and that the distance from the spacecraft to the small body is known. These algorithms have been tested using both simulated data from Comet 67P, Asteroids Eros and Itokawa; and real data from the Rosetta mission.
      • 08.0904 Design and Implementation of Power Management Algorithm for a Nano-satellite Varun Thakurta (Manipal University), Avi Jain (Manipal Institute Of Technology), Vishwanath Datla (), Akshit Akhoury (Manipal Institute of Technology), Arun Ravi (MIT), Akshiti Parashar (), Ruchitha Reddy (Manipal Institute of Technology), Harshal Dali (Manipal University ), Adhya Kejriwal (Manipal University) Presentation: Varun Thakurta - -
        This paper focuses on the design of a power management algorithm that can improve the performance and service lifetime of small satellites. Along with a highly efficient power distribution scheme, the onboard power management system plays a vital role in the operations of a satellite. Small satellites are primarily powered by solar cells. The constraints on the size and mass of a nanosatellite limit its power generation and storage ability. The harnessed energy is stored in rechargeable batteries to ensure a constant supply of power during the eclipse phase. The algorithm enforces a fixed threshold on the battery DoD and switches the satellite to a low power state on exceeding it. The power generated is estimated every orbit since it changes due to the variation in relative positions of the sun and the earth over time. The satellite turns on its payload and transmission only above very specific locations on the Earth. This allows a deeper discharge when running loads like the payload or the communication and smaller discharge when performing other low power tasks so that the average discharge remains below the threshold. Several power modes have been defined keeping in mind the inter-dependencies between the different satellite subsystems for smooth operation. The switching of these modes depends on the task to be performed by the satellite. The results show a significant improvement in power performance over an implementation without an adaptive threshold. The paper also includes the power calculations involving the solar panels, the battery and the various loads.
      • 08.0905 An Integrated System for Mixed-Initiative Planning of Manned Spaceflight Operations Martijn Ijtsma (Georgia Institute of Technology), Will Lassiter (), Karen Feigh (Georgia Tech), Martin Savelsbergh (Georgia Tech), Amy Pritchett () Presentation: Martijn Ijtsma - Tuesday, March 5th, 09:20 AM - Cheyenne
        Manned spaceflight in outer/deeper space will require crew operations that are independent of ground support. This requires the crew to re-plan day-to-day activities, particularly in the case of unforeseen circumstances. To support these planning duties, we are developing a mixed-initiative planning tool that optimizes schedules in collaboration with astronauts. This paper highlights the tool's planning algorithm. The planning algorithm has two closely-coupled components: first, an optimization algorithm (optimizer) based on local search heuristics and, secondly, a computational model of the work that is to be performed. In this framework, the optimizer acts as a surrogate model of the more detailed computational models, such that new solutions can be efficiently explored. The computational work model is capable of simulating a plan through time, and can account for dynamic interactions between activities and work environment that are not modeled in the optimizer. Moreover, the computational model returns to the optimizer metrics that reflect required teamwork to coordinate activities between astronauts. The paper includes a description of the optimizer and computational simulation models as well as a case study with activities, agents and resources that are representative of a typical manned mission.
      • 08.0906 Motion Planning for Climbing Mobility with Implementation on a Wall-Climbing Robot Keenan Albee (NASA Jet Propulsion Lab), Antonio Teran Espinoza (Massachusetts Institute of Technology), Kristina Andreyeva (), Nathan Werner (), Howei Chen (), Tamas Sarvary () Presentation: Keenan Albee - Tuesday, March 5th, 09:45 AM - Cheyenne
        Future autonomous planetary explorers will require extreme terrain mobility to reach areas of interest, such as walled lunar pits and steep Martian rock layers. Climbing mo- bility systems are one proposed answer, requiring efficient and kinematically feasible motion planning for autonomous opera- tion. Similarly, climbing planning is applicable to other micro- gravity situations requiring constant end effector contact with discrete handholds. This paper proposes a planning framework that poses kinematic climbing planning as a discrete optimal planning problem. Motion primitives are used to encourage large robot body workspaces and beneficial connections between climbing stances. A wall-climbing planner simulation is pre- sented, along with implementation on a hardware demonstra- tion testbed that successfully recognized, navigated, and climbed an arbitrary vertical wall.
      • 08.0907 A Distributed Hierarchical Framework for Autonomous Spacecraft Control Julia Badger (NASA - Johnson Space Center) Presentation: Julia Badger - Tuesday, March 5th, 10:10 AM - Cheyenne
        Future human space missions for exploring beyond low Earth orbit are in the conceptual design stage. One such mission describes a habitat in cis-lunar orbit that is visited by crew periodically, others describe missions to Mars. These missions have one important thing in common: the need for autonomy on the spacecraft. This need stems from the latency and bandwidth constraints on communications between the vehicle and ground control. A variable amount of autonomy may be necessary whether the spacecraft has crew on board or not. Spacecraft are complex systems that are engineered as a collection of subsystems. These subsystems work together to control the overall state of the spacecraft. As such, solutions that increase the autonomy of the spacecraft (called autonomous functions) should respect both the independence and interconnectedness of the spacecraft subsystems. This distributed and hierarchical approach to system monitoring and control is a key idea in the Modular Autonomous Systems Technology (MAST) framework. The MAST framework enables a component-based architecture that provides interfaces and structure to developing autonomous technologies. The framework enforces a distributed, hierarchical architecture for autonomous control systems across subsystems, systems, elements, and vehicles. An example autonomous system was implemented in this framework and tested using realistic spacecraft software and hardware simulations.
    • 08.10 Systems and Technologies for CubeSat/Smallsats Kyle Kemble (Air Force Research Laboratory) & Michael Swartwout (Saint Louis University)
      • 08.10 8.10: Automated Solar Panel Manufacturing Utilizing Surface Mount Technology Ben Bowen Presentation: Ben Bowen - - Madison
        Sierra Nevada Corporation (SNC) has developed a game-changing approach to spacecraft solar array manufacturing utilizing Surface Mount Technology (SMT). By utilizing a surface mount capable cell, industry standard pick and place automation replaces traditional, time-consuming and labor-intensive solar panel assembly processes. This new, patent-pending technology enables increased power density (W/m²), decreased dollars per watt ($/W), increased specific power (W/kg), and zero touch labor. SNC will discuss current developments in the technology along with some recent test data and upcoming flight opportunities.
      • 08.1001 Attitude Control System for the Mars Cube One Spacecraft David Sternberg (NASA Jet Propulsion Laboratory), John Essmiller (NASA Jet Propulsion Lab), Cody Colley (JPL), Andrew Klesh (Jet Propulsion Laboratory), Joel Krajewski (Jet Propulsion Laboratory) Presentation: David Sternberg - Friday, March 8th, 08:30 AM - Madison
        Abstract—CubeSats are small spacecraft based on a 10cm by 10cm by 10cm (1U) cube standard that have historically only been operated in Earth orbit. Mars Cube One (MarCO) is the first CubeSat mission developed for interplanetary operation. MarCO is a technology demonstration mission comprised of two identical, solar powered 6U satellites with several key goals, including that of providing a bent pipe telecom relay to Earth for NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission during its Entry, Descent, and Landing sequence. MarCO launched on the same rocket as InSight and makes use of the Deep Space Network for communications and ranging. It therefore has an attitude control system and propulsion system suitable for operating in several pointing modes, providing desaturations for reaction wheel momentum buildup, and thrusting to change the spacecraft trajectory. Because the spacecraft design is constrained to the CubeSat standards and because of the distances of the spacecraft from Earth and the Sun, the components used for attitude control and propulsion must meet tight size, mass, and power requirements. Autonomous modes of operation are also critical to ensure that the spacecraft can function safely with periods of several hours occurring between consecutive communication periods. A robust testing sequence was required to ensure that the spacecraft functions were exercised and that the operations team understood how the spacecraft were expected to behave after launch. This paper discusses several elements of the MarCO attitude control and propulsion systems. The paper begins with a discussion of the hardware that was selected for the two systems as well as descriptions of the interface between the attitude control and propulsion systems and the interface between these systems and the rest of the spacecraft’s command and data handling system. Next, the paper summarizes the different types of tests that were performed at the system and spacecraft levels. Test data is included for some of these tests which helped define the methods by which the spacecraft is operated in space. Lastly, the paper lists a series of lessons-learned for developing attitude control and propulsion systems for interplanetary CubeSats.
      • 08.1003 Nano-sat Scale Electric Propulsion for Attitude Control - Performance Analysis Jin S. Kang (U.S. Naval Academy), Jeffery King (U.S. Naval Academy), Jonathan Kolbeck (), Michael Sanders (US Naval Academy), Michael Keidar (George Washington University) Presentation: Jin S. Kang - Friday, March 8th, 08:55 AM - Madison
        In recent years, the complexity of CubeSat missions has been increasing steadily as the platform capabilities have drastically improved. Missions involving high-accuracy pointing and interplanetary exploration are no longer out of the reach of CubeSat-class satellites. Accordingly, the CubeSat community also has been focusing on miniaturization of propulsion systems. Thus far, these systems have been used mostly for ΔV maneuver applications and require a separate attitude control system to keep the satellite pointed in the desired direction. For fine-pointing, the currently available options are dominated by reaction-wheels and control-moment-gyros. One promising solution for this is the use of low-thrust propulsion systems for providing a combined ΔV maneuver and pointing capability. Electric propulsion systems can enable high-accuracy pointing capability while also providing orbit maneuver capability. Electric propulsion systems will not have the high slew-rate of the reaction wheels or ΔV responsiveness of conventional thrusters. However, if the main objective of the mission is in providing high-accuracy pointing, long-term stability of pointing, orbit maintenance, and long-term orbit maneuvers, multi-thruster electrical propulsion system can be substituted for the attitude control system and propulsion unit combination, resulting in volume and cost savings. This paper characterizes the performance of one such system, CubeSat attitude control system. First, the propulsion system characterization results are given. Using these performance parameters, the theoretical pointing accuracy and target dwell time are analyzed and discussed. The paper also highlights potential application of the electric propulsion system and provides comparison results of the system performance as compared to other commercially available units in terms of cost, volumetric efficiency, and resource consumption.
      • 08.1004 Near Earth Asteroid Scout CubeSat Science Data Retrieval Optimization Using Onboard Data Analysis Jack Lightholder (NASA-JPL), David Thompson (Jet Propulsion Laboratory), Julie Castillo Rogez (JPL/Caltech), Christophe Basset () Presentation: Jack Lightholder - Friday, March 8th, 09:20 AM - Madison
        Small spacecraft are continually evolving in capability and mission complexity. As spacecraft size decreases, physical limitations provide new challenges for mission designers. These include limited instrument aperture, low communications bandwidth, and reduced attitude control. Software techniques can address these limitations to retain the capabilities of larger spacecraft, in a small form factor. These techniques move the first order science analysis, which is traditionally completed on the ground, onboard the spacecraft. This can minimize the amount of bandwidth required for first order decision making. ¬ As part of the Space Launch System (SLS) Exploration Mission 1 (EM-1), the Near-Earth Asteroid Scout (NEA Scout) CubeSat mission will fly to about 1 AU to conduct a flyby of a near Earth asteroid (NEA) less than 100 m across. A 6U CubeSat, NEA Scout will be guided by a solar sail, towards its low albedo target. A combination of target orbit uncertainty and long lead times for solar sail trajectory correction maneuvers drive a requirement to identify the target in optical navigation imagery at a distance of about 60,000 km. Traditional large spacecraft accomplish this using long exposure imaging to increase SNR and identify the low albedo target. Due to the jitter inherent in a small platform, long exposure imaging in not feasible. Onboard image processing overcomes this challenge. The spacecraft aligns and combines a stack of rapidly acquired images, resulting in a single image with a higher SNR than its constituent images. We filter the aligned images using a temporal median. This solution fits within the memory constrained onboard context. Prior to alignment, each image undergoes a first order image calibration, onboard, to improve the results of the alignment. This calibration consists of a dark current subtraction, flat field adjustment and bad pixel mask application. The temporal median has the added benefit of removing transient imaging artifacts, such as cosmic rays. Interplanetary CubeSats, such as NEA Scout, are additionally physically constrained by the size of their antenna and available transmission power. At closest target approach, NEA Scout will be constrained to approximately <1 kbps downlink bandwidth. We address this limitation with automatic image cropping algorithms and software routines which downlink image statistics, giving operators a better understanding of the image content before committing it to the downlink queue. Alternatively, operators can command specific cropping operations, or as a box size around the brightest point in the image. The combination of these techniques enables early target detection in an onboard context, without stringent pointing requirements, in a low bandwidth mission scenario. These capabilities leverage onboard data processing to distill decision making data to tenable size for limited communication and low bandwidth deep space communication paradigms. This technology demonstration will pave the way for future smallsat missions to far-off destinations.
      • 08.1005 Project Implementation and Lessons Learned from the RainCube Mission Travis Imken (Jet Propulsion Laboratory), Eva Peral (), Shannon Statham (Jet Propulsion Laboratory), Shivani Joshi (Jet Propulsion Laboratory), Jonathan Sauder (Jet Propulsion Laboratory), Austin Williams (Tyvak Nano-Satellite Systems, Inc), Christopher Shaffer (Tyvak Nanosattelite Systems) Presentation: Travis Imken - Friday, March 8th, 09:45 AM - Madison
        RainCube (Radar in a CubeSat) is a technology demonstration mission to enable Ka-band precipitation radar technologies on a low-cost, quick-turnaround platform. The 6U CubeSat is currently in orbit and features a radar payload built by the Jet Propulsion Laboratory (JPL) and a spacecraft bus and operations provided by Tyvak Nano-Satellite Systems. Following the deployment of the half-meter parabolic antenna, the radar first observed precipitation over Mexico a month later. The mission has met its technology demonstration requirements and continues to collect precipitation data. This paper discusses the project engineering processes through formulation, implementation, and flight operation and concludes with lessons learned and future concepts.
      • 08.1008 Implementation of Wire Burn Deployment Mechanism Using COTS Resistors and Related Investigations Anirudh Kailaje (Manipal University), Madhav Brindavan (Manipal Institute of Technology), Pruthvi Tapadia (Manipal Insitute of Technology), Akash Paliya (Manipal Univesity), Hemant Ganti (Manipal University), Varun Thakurta (Manipal University), Aniketh Ajay Kumar (Manipal University) Presentation: Anirudh Kailaje - -
        In this paper, a specific implementation of the burn wire actuation mechanism for use in deployable peripherals of nanosatellites is presented with the focus on the advantages of using a resistor and an HMPE hold-down cable over the standard Nichrome-Nylon Setup. A simple method of adjusting the tension in the hold-down cable to adjust the contact pressure between the hold-down cable and the heat source has also been presented. The electronics design of the actuation system can provide the required power for the required duration to ensure the successful deployment along with a feedback loop to ensure if the mechanism has indeed been deployed. The design is backed by the provided experimental data to ensure the system works with the required reliability and repeatability, making the system suitable for the use in space.
      • 08.1011 Solving Thermal Control Challenges for CubeSats: Optimizing Passive Thermal Design Jennifer Young (Blue Canyon Technologies) Presentation: Jennifer Young - Friday, March 8th, 10:10 AM - Madison
        Thermal control challenges that customers face when condensing their payload into a CubeSat format will be presented by showing details of four spacecraft currently in orbit in 3U and 6U configurations. The main drivers for thermal design are component power dissipation, available radiator area with adequate view factors, and the amount of power available for heater control. On a full-sized bus, these are common and achievable tasks. For a small satellite, they can become major design drivers forcing changes to board layouts, addition of heat straps or heat pipes, and flight constraints. This presentation will explore four payloads with distinctly different temperature requirements, challenges, and outcomes. Lessons learned from these examples will lead into considerations for optimization of passive thermal design features that can improve thermal performance for future missions.
    • 08.11 Planetary Exploration Using Small Spacecraft Carolyn Mercer (NASA - Glenn Research Center) & Young Lee (Jet Propulsion Laboratory) & Andrew Petro (NASA - Headquarters)
      • 08.11 8.11 PANEL:SmallSats for Planetary Exploration: Key Enablers, Opportunities & Barriers Conor Nixon, David Bearden, Ezinne Uzo Okoro, Andrew Klesh, Charles Norton, Patricia Beauchamp Presentation: Conor Nixon, David Bearden, Ezinne Uzo Okoro, Andrew Klesh, Charles Norton, Patricia Beauchamp - - Gallatin
        Now that we have observed and experienced successful smallsat missions in low Earth orbit to Mars orbit, this panel will discuss the following questions in light of the accelerating pace of small-satellite capabilities and applications: • What has been accomplished in recent planetary smallsats (e.g., MarCo) and what challenges did they overcome? • Are smallsats ready for prime time in planetary exploration? Can they meet expectations such as longevity, performance and cost? • What mission and launch opportunities are available? • What are the technology and programmatic-related challenges or other impediments (capability, reliability, readiness, cost) exist? • What technology is being developed or approaches have been considered to overcome these impediments? What does the future of planetary smallsats look like?
      • 08.1101 Smallsat Missions Enabled by Paired Low-Thrust Hybrid Rocket and Low-Power Long-Life Hall Thruster Ryan Conversano (), Ashley Karp (Jet Propulsion Laboratory), Nathan Strange (Jet Propulsion Laboratory), Elizabeth Jens (Jet Propulsion Laboratory), Jason Rabinovitch (Jet Propulsion Laboratory, California Institute of Technology) Presentation: Ryan Conversano - Wednesday, March 6th, 05:20 PM - Gallatin
        The capabilities of a SmallSat-class spacecraft targeting the outer solar system and using a combined chemical and electric propulsion system are explored. The development of compact hybrid rockets has enabled high-thrust engines to be packaged tightly enough to fit on CubeSat and SmallSat spacecraft. These hybrid rockets provide 10’s-100 N of thrust depending on the propellant load & >300 s of specific impulse and have been demonstrated in both ambient and vacuum environments. Advancements in low-power long-life Hall thruster technologies have provided the potential for significantly greater propellant throughputs, enabling their use as a primary propulsion element on interplanetary spacecraft. In a recent characterization test campaign, the MaSMi-DM Hall thruster demonstrated power throttling from 150 – 1000 W with >1500 s of specific impulse available at >500 W and >40% total thrust efficiency available at >300 W; peak values of 1940 s and 53% were observed. A notional low-mass spacecraft employing a combined hybrid rocket and low-power electric propulsion system was designed and used for mission concept analysis targeting the outer solar system. Using an imposed wet mass limit of 400 kg, mission trajectories to Saturn and Uranus were generated. Orbit capture with >40% of the launch mass was shown to be possible at either target, with mission transfer times of 7.5 years and 13.5 years for Saturn and Uranus, respectively. Significant follow-on mission activities near Saturn (e.g. to Titan & Enceladus) were also possible by carrying extra propellant mass while remaining under the total wet mass limit.
      • 08.1102 SmallSat Aerocapture to Enable a New Paradigm of Planetary Missions Alex Austin (Jet Propulsion Laboratory), Adam Nelessen (Jet Propulsion Laboratory), Ethiraj Venkatapathy (NASA ARC), Robert Braun (Georgia Institute of Technology), William Strauss (NASA Jet Propulsion Lab), Robin Beck (NASA - Ames Research Center), Paul Wercinski (), Gary Allen (NASA Ames Research Center), Michael Werner (), Evan Roelke (University of Colorado Boulder) Presentation: Alex Austin - Wednesday, March 6th, 04:30 PM - Gallatin
        This paper presents a technology development initiative focused on delivering SmallSats to orbit a variety of bodies using aerocapture. Aerocapture uses the drag of a single pass through the atmosphere to capture into orbit instead of relying on large quantities of rocket fuel. Using drag modulation flight control, an aerocapture vehicle adjusts its drag area during atmospheric flight through a single-stage jettison of a drag skirt, allowing it to target a particular science orbit in the presence of atmospheric uncertainties. A team from JPL, NASA Ames, and CU Boulder has worked to address the key challenges and determine the feasibility of an aerocapture system for SmallSats less than 180kg. Key challenges include the ability to accurately target an orbit, stability through atmospheric flight and the jettison event, and aerothermal stresses due to high heat rates. Aerocapture is a compelling technology for orbital missions to Venus, Mars, Earth, Titan, Uranus, and Neptune, where eliminating the propellant for an orbit insertion burn can result in significantly more delivered payload mass. For this study, Venus was selected due to recent NASA interest in Venus SmallSat science missions, as well as the prevalence of delivery options due to co-manifesting with potentially many larger missions using Venus for gravity assist flybys. In addition, performing aerocapture at Venus would demonstrate the technology’s robustness to aerothermal extremes. A survey of potential deployment conditions was performed that confirmed that the aerocapture SmallSat could be hosted by either dedicated Venus-bound missions or missions performing a flyby. There are multiple options for the drag skirt, including a rigid heat shield or a deployable system to decrease volume. For this study, a rigid system was selected to minimize complexity. A representative SmallSat was designed to allocate the mass and volume for the hardware needed for a planetary science mission. In addition, a separation system was designed to ensure a clean separation of the drag skirt from the flight system without imparting tipoff forces. The total spacecraft mass is estimated to be 68 kg, with 26 kg of useful mass delivered to orbit for instruments and supporting subsystems. This is up to 85% more useful mass when compared to a propulsive orbit insertion, depending on the orbit altitude. Key to analyzing the feasibility of aerocapture is the analysis of the atmospheric trajectory, which was performed with 3 degree-of-freedom simulations and Monte Carlo analyses to characterize the orbit targeting accuracy. In addition, aerothermal sizing was performed to assess thermal protection system requirements, which concluded that mature TPS materials are adequate for this mission. CFD simulations were used to assess the risk of recontact by the drag skirt during the jettison event. This study has concluded that aerocapture for SmallSats could be a viable way to increase the delivered mass to Venus and can also be used at other destinations. With increasing interest in SmallSats and the challenges associated with performing orbit insertion burns on small platforms, this technology could enable a new paradigm of planetary science missions.
      • 08.1104 Stage-Based Electrospray Propulsion System for Deep-Space Exploration with CubeSats Oliver Jia Richards (MIT), Paulo Lozano () Presentation: Oliver Jia Richards - Wednesday, March 6th, 09:00 PM - Gallatin
        Independent deep-space CubeSat missions require efficient propulsion systems capable of delivering several km/s of delta-V. The ion Electrospray Propulsion System under development at MIT's Space Propulsion Laboratory is a high delta-V propulsion system that is a promising technology for propulsion of independent deep-space CubeSat missions due to its mechanical simplicity and small form factor. However, current electrospray thrusters have demonstrated lifetimes up to an order of magnitude lower than the required firing time for a mission to a near-Earth asteroid starting from geostationary orbit. A stage-based concept is proposed where the propulsion system consists of a series of electrospray thruster arrays. When a set of thrusters reaches its lifetime limit, it is ejected from the spacecraft exposing new thrusters thereby increasing the overall lifetime of the propulsion system. Such a staging strategy is usually not practical for in-space thrusters. However, the compactness of micro-fabricated electrospray thrusters means that their contribution to the overall spacecraft mass and volume is small relative to other subsystems. Mechanisms required for this stage-based approach are proposed and demonstrated in a vacuum environment. In addition, missions to several near-Earth asteroids with orbital elements similar to those of Earth are analyzed with a particular focus on the escape trajectory. With a stage-based approach, independent deep-space CubeSat missions become feasible from a propulsion standpoint.
      • 08.1105 Mars Small Spacecraft Mission Concepts Study Nathan Barba (Jet Propulsion Laboratory), Tom Komarek (Jet Propulsion Laboratory), Ryan Woolley (Jet Propulsion Laboratory), Lou Giersch (NASA Jet Propulsion Lab), Vlada Stamenkovic (JPL), Michael Gallagher (JPL), Charles Edwards (Jet Propulsion Laboratory) Presentation: Nathan Barba - Thursday, March 7th, 10:35 AM - Dunraven
        NASA’s Mars Exploration Program is studying a potential Mars Sample Return (MSR) campaign consisting of a series of missions over the next decade that would return samples collected at Mars for analysis in terrestrial laboratories. It is anticipated that during such a campaign, many in the Mars science community would seek to continue high-priority science investigations in parallel to those provided by geological and astrobiological sample return investigations. To respond to this anticipated desire of the science community, JPL is performing a study of small spacecraft mission concepts to Mars that could bridge the gap between MSR and other desired science investigations at Mars. The goal of the study is to utilize smaller, affordable missions in performing high-priority science investigations as defined in the National Academy of Sciences Decadal Survey, Mars Exploration Program Analysis Group (MEPAG) goals, and Human Exploration and Operations (HEO) Strategic Knowledge Gaps. The study targets the use of small spacecraft with greater science capability than currently achievable with CubeSats. The target spacecraft wet mass is approximately 100 to 350 kilograms. Methods of access to Mars considered in this study include a self-propelled transit from Earth geosynchronous transfer orbit (GTO) to Mars as a secondary payload in a rideshare configuration. The study investigates mission concepts, science objectives, mission designs, concept of operations, enhancing technologies, and mission costs, along with launch vehicle interfaces. The cost estimates of the mission concepts studied range from below $100 million to less than $300 million for development through launch. This paper concludes with an outline of several examples of small spacecraft mission concepts to Mars that demonstrate significant scientific capability, are technically feasible, and fit within the desired cost range.
      • 08.1106 Optimized Low-Thrust Transfers from Geostationary Transfer Orbit to Mars Ryan Woolley (Jet Propulsion Laboratory), Zubin Olikara (NASA Jet Propulsion Laboratory) Presentation: Ryan Woolley - Wednesday, March 6th, 09:25 PM - Gallatin
        A small spacecraft has three primary methods to get to Mars: by a dedicated launch vehicle, by sharing a ride with another Mars-bound mission, or via rideshare to Earth orbit and making its own way to the Red Planet. The third option may be the most attractive in terms of cost effectiveness and frequency of access, which are the main drawbacks of the first two, respectively. In the past 5 years, over 50 satellites have been launched from U.S. soil en route to geosynchronous orbit and beyond. Many of these launches do not use the full capability of the launch vehicle, leaving an opportunity for a small secondary spacecraft to get a ride to geosynchronous transfer orbit (GTO). Starting from an ESPA-ring rideshare to GTO, a solar-electric propulsion (SEP) powered spacecraft can make its own way to Mars orbit to perform a useful mission. In this paper, we explore the mission design space for small, ESPA-class (200-450 kg) spacecraft transferring from GTO to Mars orbit. This is accomplished by creating tools that jointly optimize low-thrust trajectories and spacecraft subsystems to create feasible mission concepts. An example is given of an Areostationary telecom orbiter that reaches Mars in 2 years with a dry mass of 200 kg.
      • 08.1107 Hybrid Propulsion System Enabling Orbit Insertion Delta-Vs within a 12 U Spacecraft Elizabeth Jens (Jet Propulsion Laboratory), Ashley Karp (Jet Propulsion Laboratory), Jason Rabinovitch (Jet Propulsion Laboratory, California Institute of Technology), Barry Nakazono () Presentation: Elizabeth Jens - Wednesday, March 6th, 09:50 PM - Gallatin
        This paper describes the design and development status of a hybrid CubeSat propulsion system. This system is designed to be packaged within a 12 U envelope and deliver approximately 800 m/s of DeltaV to a 25 kg spacecraft. The hybrid motor uses green propellants, specifically gaseous oxygen as the oxidizer and solid Poly(Methyl MethAcrylate) (PMMA), also known as acrylic, as the fuel. This propellant combination is separated by phase and is non-toxic and non-hypergolic, making the design well suited for use within a secondary payload where safety is paramount. The hybrid motor has high performance with an Isp of approximately 300 s and is able to be re-ignited, enabling numerous maneuvers to be conducted. The system also provides thrust vector control during main motor operation and attitude control for reaction wheel un-loading during the science mission phase. A dedicated test program has been conducted at the Jet Propulsion Laboratory over the past three years to progress this design towards flight and verify the design assumptions. This paper will summarize the results of this test program and the demonstrated performance of the motor. A path to progress this system towards flight shall also be discussed.
      • 08.1110 InSight/MarCO Opportunistic Multiple Spacecraft per Antenna (OMSPA) Demonstration Andre Tkacenko (Jet Propulsion Laboratory) Presentation: Andre Tkacenko - -
        As smallsats become increasingly capable, longer-lived, and have more secondary payload launch opportunities to beyond-GEO destinations, they are expected to play an increasing role in deep space science investigations. This expectation is borne out by several relatively recent NASA Science Mission Directorate solicitations regarding smallsat studies and small innovative missions. With the potential for these smallsats to substantially add to the number of spacecraft operating in deep space, we need to be thinking about ways to support communications with all of them without the huge expense of trying to build a commensurate number of deep space antennas. One approach to this challenge might involve making greater use of beam sharing techniques that allow all the spacecraft within the beamwidth of a single ground antenna to simultaneously downlink to the antenna. One of these techniques, Opportunistic Multiple Spacecraft Per Antenna (OMSPA), may be particularly suited to smallsats. In the concept for this technique, smallsats within the scheduled ground antenna beam of some other spacecraft, make opportunistic use of that spacecraft’s beam by transmitting “open-loop” to a recorder associated with the antenna. These transmissions get captured on the recorder and can be later retrieved, demodulated, and decoded so that the smallsats can recover their data – all without them having to schedule the antenna itself and compete with larger missions for antenna time. Widespread use of such a technique might lead to more efficient use of receiver antenna resources and result in a dramatic increase in downlink throughput. An opportunity to demonstrate the technique occurred in May 2018, when the Mars CubeSat One (MarCO) mission, consisting of two nanospacecraft (MarCO-A & B) launched alongside InSight, a NASA Mars lander mission. To demonstrate the capabilities of OMSPA for this launch window opportunity, X-band downlink telemetry was recorded for all three spacecraft (InSight, MarCO-A, and MarCO-B) at both the Deep Space Network (DSN), using its 34m antennas, and at Morehead State University (MSU) using its 21-m antenna – with all of the involved antennas pointed at InSight. Open-loop recordings (OLRs) were collected at the DSN using wideband very long baseline science receivers and at MSU using Universal Software Radio Peripheral (USRP) devices operated using GNU Radio. All the recordings were then processed at the Jet Propulsion Laboratory, California Institute of Technology (JPL) using an OMSPA Software Receiver, a signal processing/communications tool used to extract telemetry transfer frames from baseband samples. The results of extracting telemetry data from InSight/MarCO recordings collected by the DSN and at MSU are described in this article. In particular, details pertaining to the processing chain used by the OMSPA Software Receiver to demodulate the DSN and MSU recordings are presented, from carrier/symbol synchronization, to frame alignment using attached sync markers (ASMs), followed by error correction code decoding. Validation results with closed-loop data obtained by the DSN are also presented in order to highlight the viability of OMSPA for future multiple spacecraft demodulation opportunities.
      • 08.1111 Attitude Control of CubeSat Swarm for Visual Mapping of Planetary Bodies Ravi Teja Nallapu (University of Arizona), Jekan Thangavelautham (University of Arizona) Presentation: Ravi Teja Nallapu - Thursday, March 7th, 10:10 AM - Dunraven
        Attitude control strategies used in an automated spacecraft swarm design tool which will be applied to design visual mapping of small bodies.
      • 08.1112 TEAM – Titan Exploration Atmospheric Microprobes Conor Nixon (NASA GSFC) Presentation: Conor Nixon - Thursday, March 7th, 11:00 AM - Dunraven
        We describe a novel mission architecture to investigate the lower atmosphere of Saturn’s moon, Titan. Titan is the only moon in the solar system to possess a dense atmosphere, which has important similarities to, and differences from, the Earth. Like Earth, Titan has lakes and seas on its surface – although these are composed of liquid hydrocarbons and not water. The mission is comprised of two elements: (1) A small satellite module (PCV, Probe Carrier Vehicle) that is deployed from a host Saturn system mission spacecraft (NASA small or medium class mission: Discovery or New Frontiers) and acts as a carrier and data relay for the entry probes; (2) Four atmospheric entry probes (EP), one per ~10° latitude from 60-90°N, that aerobrake and descend under parachute from ~135 km to the surface, measuring profiles of temperature, winds and gas composition during the descent. Multiple probes at different latitudes are required to constrain the spatial variation in cloud formation, precipitation and the implications for lake composition. The mission would require a ride-share to reach the Saturn system: currently three of the seven anticipated New Frontiers mission destinations are in the Saturn System: Saturn Probe, Enceladus and Titan itself. The TEAM mission is designed to be largely independent once deployed in the Saturn system, however the prime mission spacecraft (New Frontiers, Discovery) will provide a backup data relay from the PCV to the Earth. Key mission challenges include thermal management and probe release/navigation.
      • 08.1113 Extended Mission Technology Demonstrations Using the ASTERIA Spacecraft Lorraine Fesq (Jet Propulsion Laboratory), Patricia Beauchamp (Jet Propulsion Laboratory), Swati Mohan (NASA Jet Propulsion Laboratory), David Sternberg (NASA Jet Propulsion Laboratory), Martina Troesch (Jet Propulsion Laboratory (California Institute of Technology)), Mary Knapp (Massachusetts Institute of Technology) Presentation: Lorraine Fesq - Wednesday, March 6th, 04:55 PM - Gallatin
        JPL is using the Arcsecond Space Telescope Enabling Research In Astrophysics (ASTERIA) CubeSat space telescope as a platform to demonstrate new software technologies. ASTERIA currently is operating in low-Earth orbit and has completed its prime mission of demonstrating unprecedented photometric precision for a CubeSat mission by detecting known transiting exoplanets. During extended operations, science will continue, plus three experiments will be performed. First, a smart executive/planner will be uploaded that will shift the current spacecraft operations paradigm from open-loop sequence-based commanding to closed-loop command execution by introducing “task networks.” Second, autonomous navigation software will demonstrate onboard orbit determination in low Earth orbit without using the Global Positioning System; this activity will demonstrate a fully independent means of spacecraft orbit determination for Earth orbiters using only passive imaging of small bodies and possibly other orbiting spacecraft. Finally, ASTERIA’s attitude control system will be commanded into different configurations to characterize the spacecraft pointing jitter as a function of target brightness, reaction wheel speed, controller gain, and number of guide stars. The data from these jitter experiments will be valuable not only for this current mission but also for future missions using similar attitude control hardware. In addition to these technology demonstrations, the spacecraft will continue performing mission science: ASTERIA is uniquely suited to perform long-term monitoring of stars such as alpha Centauri to detect possible small, transiting planets. The discovery of a transiting Earth-sized planet around alpha Cen A and/or B is considered of high scientific value as such a planet would be our closest exo-planetary neighbor orbiting a Sun-like star.
    • 08.12 Systems and Technologies for Ascent from Planetary Bodies, a Multidisciplinary Problem Tara Polsgrove (NASA Marshall Space Flight Center) & Ashley Karp (Jet Propulsion Laboratory)
      • 08.1201 Qualification of a Hybrid Propulsion System for the Mars Ascent Vehicle Britt Oglesby (NASA - Marshall Space Flight Center), Andrew Prince (NASA - Marshall Space Flight Center), George Story (NASA - Marshall Space Flight Center), Ashley Karp (Jet Propulsion Laboratory) Presentation: Britt Oglesby - Thursday, March 7th, 11:25 AM - Madison
        Technology for a hybrid-based propulsion system is being developed to support a potential Mars Sample Return campaign. A Mars Ascent Vehicle (MAV) concept for launching samples off of Mars, and delivering them to orbit for further transport to Earth may utilize hybrid propulsion due to the option’s predicted favorable low temperature characteristics and high performance. However, the hybrid option is still undergoing technology development to demonstrate these benefits. Once development of a capable hybrid propulsion system is proven, further work will still be required to fully qualify the system.
      • 08.1202 Hybrid Propulsion Technology Development for a Potential Near-Term Mars Ascent Vehicle Ashley Karp (Jet Propulsion Laboratory), Barry Nakazono (), George Story (NASA - Marshall Space Flight Center), Jessica Chaffin (NASA - Marshall Space Flight Center), Gregory Zilliac (MCT/NASA Ames Research Center) Presentation: Ashley Karp - Thursday, March 7th, 10:10 AM - Madison
        A technology development program for a potential hybrid Mars Ascent Vehicle (MAV) is currently underway to enable its infusion into a potential Mars Sample Return (MSR) campaign as early as 2026. A NASA team from the Jet Propulsion Laboratory (JPL), Marshall Space Flight Center (MSFC) and Ames Research Center (ARC) is leading and coordinating this program. A new propellant combination: the wax-based fuel, SP7, and MON-30 were proposed for a hybrid option for the MAV propulsion system several years ago. Since that time, hotfire testing with a similar propellant combination (SP7/MON-3) has been completed and a pathway to achieving high performance with the flight propellant combination is currently being pursued. Highlights of the progress to date and plans for risk reduction and the next steps in hybrid technology will be presented.
      • 08.1203 Mars Ascent Vehicle (MAV) Vehicle Systems Overview Lisa Mc Collum (NASA - Marshall Space Flight Center), Quincy Bean (), Andrew Prince (NASA - Marshall Space Flight Center), Darius Yaghoubi (NASA - Marshall Space Flight Center), Andrew Schnell (NASA Marshall Space Flight center) Presentation: Andrew Prince - Thursday, March 7th, 08:55 AM - Madison
        The Advanced Concepts Office (ACO) at Marshall Space Flight Center (MSFC) has conducted ongoing studies and trades into options for both hybrid and solid vehicle systems for potential Mars Ascent Vehicle (MAV) concepts for the Jet Propulsion Laboratory (JPL). Two MAV propulsion options are being studied for use in a potential Mars Sample Retrieval (MSR) campaign. The following paper describes the current concepts for hybrid and solid propulsion vehicles for MAV as part of a potential MSR campaign, and provides an overview of the ongoing studies and trades for both hybrid and solid vehicle system concepts. Concepts and options under consideration for vehicle subsystems include reaction control system (RCS), separation, and structures will be described in terms of technology readiness level (TRL), benefit to the vehicle design, and associated risk. A hybrid propulsion system, which uses a solid fuel core and liquid oxidizer, is currently being developed by JPL with support from MSFC. This type of hybrid propulsion vehicle would allow the MAV to be more flexible at the cost of higher complexity, in contrast to the solid propulsion vehicle that is simpler, but allows less flexibility. The solid propulsion vehicle study performed by MSFC in 2018 further refined the solid propulsion system sizing as well as added definition to vehicle subsystem concepts, including the RCS, structures and configuration, interstage and separation, aerodynamics, and power/avionics. The studies were performed using an iterative concept design methodology, engaging subject matter experts from across MSFC’s propulsion and vehicle systems disciplines as well as seeking trajectory feedback from analysts at JPL.
      • 08.1204 Mars Ascent Vehicle (MAV) Propulsion Subsystems Design Quincy Bean (), Lisa Mc Collum (NASA - Marshall Space Flight Center), Andrew Prince (NASA - Marshall Space Flight Center) Presentation: Quincy Bean - Thursday, March 7th, 09:20 AM - Madison
        This presentation discusses the preliminary development of the propulsion systems for a two stage Mars Ascent Vehicle (MAV) for a potential Mars Sample Retrieval (MSR) mission. Each stage of the vehicle utilizes a solid rocket motor for main propulsion and a reaction control system (RCS) is housed on the second stage. This presentation discusses the design approach for the solid rocket motors and RCS system as well as ongoing and future trade studies.
      • 08.1205 Mars Ascent Vehicle Propulsion System Solid Motor Technology Plans Andrew Prince (NASA - Marshall Space Flight Center), Lisa Mc Collum (NASA - Marshall Space Flight Center), Quincy Bean () Presentation: Andrew Prince - Thursday, March 7th, 09:45 AM - Madison
        Recent trades have taken place on solid propulsion options to support a potential Mars Sample Retrieval Campaign. Mass and dimensional requirements for a Mars Ascent Vehicle (MAV) are being assessed. One MAV vehicle concept would utilize a solid propulsion system. Key challenges to designing a solid propulsion system for MAV include low temperatures beyond common tactical and space requirements, performance, planetary protection, mass limits, and thrust vector control system. Two solutions are addressed, a modified commercial commercially available system, and a tailored system.
      • 08.1206 A Survey of Lunar Sample Return Mission Concepts Thomas Percy (SAIC), Robert Hetterich (NASA - Marshall Space Flight Center), Debra Needham (NASA/MSFC) Presentation: Thomas Percy - Thursday, March 7th, 08:30 AM - Madison
        Recent announcements by NASA indicate a renewed interest in lunar surface exploration. A plan is emerging for a robust robotic surface exploration program with capacity to land significant science payloads in various regions of the moon. Desired science investigations cover a wide range of disciplines which hope to unlock the secrets of the Moon’s composition and provide insights into the history of the solar system. It has long been believed that returning samples from the lunar surface will support several of these goals, teaching us about the structure and composition of the moon, the bombardment history of the inner solar system, and assisting in the search for lunar volatiles which provide insights into the history of the solar system and may be the key to enabling long-duration human exploration. In the course of revisiting the development of lunar sample return mission and spacecraft concepts, the Advanced Concepts Office and Marshall Space Flight Center has collected background information on several lunar sample return mission concepts that have been previously developed. This paper provides a summary of these missions as well as a comparison of their key features, intended goals, operational architectures, and key performance and design metrics. First, some background is provided on the scientific importance of sample return missions and some of the key scientific requirements. A summary of eight different mission concepts is also provided. These mission concepts have been developed by a wide range of groups. The study set includes both domestic and international government agencies as well as concepts developed by commercial entities. They include both robotic and human assisted sample return architectures. The spacecraft design space is diverse with some concepts performing entirely with solid rocket motors while others use novel liquid propulsion approaches. The concepts also represent a wide range of planned sample sizes and several approaches to sample return to Earth. This paper provides both qualitative and quantitative comparisons of these mission concepts, addressing the differences in the key features of the various spacecraft designs, mission architectural approaches, and key performance metrics such as overall vehicle weight and returned sample size. The intent of this paper is to provide a single source overview of past lunar sample return mission concepts that may help guide the development of new approaches and mission concepts for NASA’s next wave of lunar science investigations. Robotic science exploration of the moon can provide unique insights into the history of the solar system and how it works. Robotic science exploration is also a key to supporting the eventual return of humans to the lunar surface. And sample return missions will be at the forefront of any program planning as we embark on this new era robotic science exploration.
      • 08.1207 Mars Ascent Vehicle Hybrid Motor Development Testing George Whittinghill (Whittinghill Aerospace) Presentation: George Whittinghill - Thursday, March 7th, 11:00 AM - Madison
        The Jet Propulsion Laboratory (JPL) is designing a Mars Ascent Vehicle (MAV) as part of a potential Mars Sample Return mission to boost collected samples from the surface to Mars orbit for eventual return to Earth. Due to some unique requirements for high performance, storability and survivability at low surface temperatures, JPL has selected a unique hybrid motor for single stage to orbit boost propulsion. The 6,050 N (1,360 lb) thrust hybrid rocket motor will be fed with MON30 as the oxidizer and will burn a specialized formulation of a paraffin fuel named SP7 in a single circular port configuration. Total burn time is slated to be ~115 seconds. This paper presents the recent development of four full-scale MAV motors at Whittinghill Aerospace. Propulsion testing began with MON03. Burn times have ranged from 20 to 90 continuous seconds, including an automated two-burn ascent profile consisting of a 85 second burn, shutdown and 15 second delay, followed by a 5 second “orbit injection” burn. The motors have demonstrated good stability and combustion efficiency throughout the burn. Two of the motors featured liquid injection thrust vector control with MON03 as the injectant. The figures of merit of Isp, c* efficiency, side Isp, SP7 regression and mechanical performance, fuel utilization, and throat erosion were evaluated. The test results are very encouraging, and point to a viable propulsion solution for the MAV.
      • 08.1208 Development and Testing of SP7 Fuel for Mars Ascent Vehicle Application Brian Evans (Space Propulsion Group, Inc), Brian Cantwell (Stanford University) Presentation: Brian Evans - Thursday, March 7th, 10:35 AM - Madison
        A new solid fuel formulation called SP7 was developed for application in a hybrid rocket propulsion system for a potential Mars Ascent Vehicle (MAV). The new fuel offers good propulsive performance (Isp) while meeting the storage and operation requirements placed upon the proposed mission. Mixed Oxides of Nitrogen (MON) are selected for the oxidizer due to the low freezing points possible with these materials. The low temperature capabilities of the fuel and oxidizer reduce the required energy associated with thermal management systems. Evaluation of the propulsive performance of SP7 was completed with two oxidizers, N2O and MON, in a 2.7-in hybrid rocket motor. In addition to the baseline fuel, metallized formulations with 20% by weight aluminum particles were also tested. Ignition and stable combustion were demonstrated with both oxidizers over a wide range of operating conditions. Static test firing of SP7 demonstrated the ability for this fuel to meet the propulsion requirements of the as designed potential MAV mission.
      • 08.1211 Update to Mars Ascent Vehicle Design for Human Exploration Tara Polsgrove (NASA Marshall Space Flight Center), Thomas Percy (SAIC), Michelle Rucker (National Aeronautics and Space Administration) Presentation: Tara Polsgrove - Thursday, March 7th, 11:50 AM - Madison
        This paper presents an overview of the current Mars Ascent Vehicle reference design used in NASA’s human Mars mission studies, and includes a description of the operations, configuration, subsystem design, and a vehicle mass summary.
  • 9 Air Vehicle Systems and Technologies Kendra Cook (C2 International, LLC) & Christian Rice (Naval Air Systems Command, Patuxent River, MD. ) & Tom Mc Ateer (NAVAIR)
    • 09.01 Air Vehicle Flight Testing Brian Kish (Florida Institute of Technology) & Christopher Gavin (AIRTEVRON TWO ONE)
      • 09.0102 Towards the Design of a 3D Printable Prandtl Box-Wing Unmanned Aerial Vehicle Luca De Vivo Nicoloso (University of California, San Diego), Falko Kuester (University of California, San Diego), Danny Tran () Presentation: Luca De Vivo Nicoloso - Sunday, March 3th, 04:30 PM - Cheyenne
        This paper explores the design of a 3D printable Prandtl Box-Wing UAV suitable for long-endurance solar powered flight. Long-endurance UAVs, enabling extended imaging campaigns and beyond-horizon communication in support of remote exploration, environmental assessment, disaster and post-disaster reconnaissance and assistance, hold great promise for data-driven decision making. Yet, they also create a range of unique challenges for the vehicle design, propulsion system and power source, navigation and guidance and payload package. The presented UAV design is a joined box-wing monocoque, a biplane with oppositely swept wings, with wing tips interconnected by winglets, offering a range of structural design optimization opportunities, aimed at providing a balance between, flight performance, efficiency, flutter resistance, and adequate surface area for solar power generation, with a wingspan allowing for easy field deployment. The wing and its payload oriented fuselage are the result of aerodynamic, topology and structural optimization algorithms, focused on enhancing structural resilience and weight, hand-in-hand with efficiency and sustainability of the resulting airframe. The Aerodynamics of the wing were analyzed using high fidelity Computer Fluid Dynamic (CFD) with the goal of optimizing the Lift/Drag ratio of the wing, winglet and fuselage. In addition we performed high fidelity Finite Element Method (FEM) analysis on spars, ribs, skins, the box wing and the assembly of all the structural components. This will allowed us to optimize material allocation in order to reduce weight and maximize the flight time of the vehicle. Mechanical and electrical components were chosen to optimize vehicle autonomy and automatically placed by an optimization algorithm aimed at properly placing all components inside the fuselage envelope, while maintaining the center of gravity target where desired, allowing for tasks specific optimization functions for the overall system. Using a combination of additive and composite manufacturing, the UAV can be entirely built using thermoplastics and fiber reinforced polymer.
      • 09.0105 Comparing Specific Excess Power of Five General Aviation Aircraft Brian Kish (Florida Institute of Technology), Markus Wilde (Florida Institute of Technology) Presentation: Markus Wilde - Sunday, March 3th, 04:55 PM - Cheyenne
        Florida Institute of Technology partnered with the FAA Small Aircraft Directorate to conduct flight tests characterizing the specific excess power of five general aviation aircraft. The objective of this flight campaign was to compare and contrast performance characteristics among representative single-engine general aviation aircraft. The data produced in the campaign contributes to an effort to create a regulatory environment that uses advances in technology to enhance general aviation safety, while reducing the effort, time and cost associated with the certification of new equipment. Loss of control continues to plague general aviation. Predictive displays and warning systems informing pilots about the aircraft’s current energy state, the amount of excess power available, and the control inputs needed to transition to a “healthy” energy state have the potential to reduce the chance for loss of control. This paper contributes data on the amount of excess power available. Examining the data for five aircraft will offer developers of prediction algorithms and warning systems common features to consider for their code logic. Lessons learned in the execution of this flight test program, as well as suggestions for future research, are provided.
      • 09.0106 Trim Forces and Free Response to Configuration Changes on General Aviation Aircraft Brian Kish (Florida Institute of Technology), Markus Wilde (Florida Institute of Technology) Presentation: Brian Kish - Sunday, March 3th, 05:20 PM - Cheyenne
        This paper examines airplane response to flap extension on seven general aviation airplanes. The scenario involves a pilot flying in the traffic pattern who becomes distracted, abruptly extends flaps while looking outside the airplane, and fails to notice airspeed and pitch-attitude changes. In the Code of Federal Regulation §23.143, the Federal Aviation Administration requires no more than 50 pounds of pitch wheel force to arrest any un-commanded airplane pitch response. The airplanes tested in this report had pitch forces less than 40 pounds. Despite satisfying the FAA requirement, data gathered in-flight showed a pitch-up to more than 30 degrees in 5 seconds after flap extension, subsequently causing airspeed to drop below stall speed for four of the airplanes. If the pilot did not compensate for this response with positive pitch inputs on the controls, the airplanes would have stalled. At traffic pattern altitudes, stalling an airplane can be fatal. The National Transportation Safety Board listed over 1000 accidents caused by loss of control in the traffic pattern between 1982 and 2015. Since general aviation airplanes do not carry flight data recorders, it is unknown how many of those accidents may have involved stalls caused by un-commanded response after flap extension. From the data gathered in-flight, it seems possible some were. To improve safety, airplane developers could interconnect flaps with the elevator, reduce horizontal tail size, or use a T-tail. The FAA should consider reducing the maximum pitch stick and wheel forces in CFR §23.143 to 20 pounds or less.
    • 09.02 UAV Systems & Autonomy Luis Gonzalez (Queensland University of Technology) & Kendra Cook (C2 International, LLC) & Frances Zhu (Cornell University)
      • 09.0203 A Generalized Multi-Objective Framework for UAV Mission Planning Babak Salamat ( Alpen-Adria-Universität ), Andrea Tonello (University of Klagenfurt) Presentation: Babak Salamat - -
        We present a framework for mission/trajectory planning of UAVs. The problem considers important objectives and constraints. Then, a multi-objective multi-constraints optimization problem is formulated. Numerical results are reported to both verify performance and mission feasibility as well as to determine computation time which is a key element to be considered for real-time applications.
      • 09.0206 Visual-Thermal Landmarks and Inertial Fusion for Navigation in Degraded Visual Environments Shehryar Khattak (University of Nevada, Reno), Christos Papachristos (University of Nevada, Reno), Kostas Alexis (Univeristy of Nevada, Reno) Presentation: Shehryar Khattak - Wednesday, March 6th, 08:30 AM - Lamar/Gibbon
        During the past decade, aerial robots have seen an unprecedented expansion in their utility as they take on more tasks which had typically been reserved for humans. With an ever widening domain of aerial robotic applications, including many mission critical tasks such as disaster response operations, search and rescue missions and infrastructure inspection taking place in GPS--denied environments, the need for reliable autonomous operation of aerial robots has become crucial. To accomplish their tasks, aerial robots operating in GPS-denied areas rely on a multitude of sensors to localize and navigate. Visible spectrum camera systems correspond to the most commonly used sensing modality due to their low cost and weight rendering them suitable for small aerial robots in indoor or broadly GPS--denied settings. However, in environments that are visually--degraded such as in the conditions of poor illumination, low texture, or presence of obscurants including fog, smoke and dust, the reliability of visible light cameras deteriorates significantly. Nevertheless, maintaining reliable robot navigation in such conditions is essential if the robot is to perform many of the critical applications listed above. In contrast to visible light cameras, thermal cameras offer visibility in the infrared spectrum and can be used in a complementary manner with visible spectrum cameras for robot localization and navigation tasks, without paying the significant weight and power penalty typically associated with carrying other sensors such as 3D LiDARs or a RADAR. Exploiting this fact, in this work we present a multi--sensor fusion algorithm for reliable odometry estimation in GPS--denied and degraded visual environments. The proposed method utilizes information from both the visible and thermal spectra for landmark selection and prioritizes feature extraction from informative image regions based on a metric over spatial entropy. Furthermore, inertial sensing cues are integrated to improve the robustness of the odometry estimation process. The proposed method works in real-time, fully on-board an aerial robot. To verify our solution, a set of challenging experiments were conducted inside a) an obscurants-filed machine shop--like industrial environment, as well as b) a dark subterranean mine in the presence of heavy airborne dust.
      • 09.0207 Autonomous Navigation and Mapping in Underground Mines Using Aerial Robots Shehryar Khattak (University of Nevada, Reno), Christos Papachristos (University of Nevada, Reno), Frank Mascarich (University of Nevada, Reno), Kostas Alexis (Univeristy of Nevada, Reno) Presentation: Shehryar Khattak - Wednesday, March 6th, 08:55 AM - Lamar/Gibbon
        This work presents an integrated approach for autonomous navigation and mapping in underground mines using aerial robots. Underground mines present a set of critical challenges as they are not only GPS-denied by nature, but their environmental circumstances also lead to severe sensor degradation (due to combinations of darkness, dust, and smoke), localizability problems (due to textureless surfaces and locally self-similar structure), while also presenting stringent navigation conditions as a result of certain very narrow geometries. To address these issues, we employ fusion of visual and thermal cameras, 3D LiDAR, as well as Inertial Measurement Unit cues to provide reliable pose estimation and mapping of the surroundings despite the sensing degradation, and enable autonomous navigation. Using a path planning strategy for collision--avoidance and autonomous exploration that is based on a receding horizon sampling--based algorithm, we demonstrate real field experiments inside underground metal mines in Northern Nevada. The presented results correspond to the navigation and mapping of mine drifts and headings and involve environments that are completely dark, dust--filled, and particularly textureless. As shown however, the proposed approach ensures the robust and reliable autonomous navigation of aerial robots in such environments, alongside their consistent mapping.
      • 09.0211 A Framework for UAV Navigation and Exploration in GPS-denied Environments Fernando Vanegas Alvarez (Queensland University of Technology), Luis Gonzalez (Queensland University of Technology), Jonathan Roberts () Presentation: Ory Walker - Wednesday, March 6th, 09:20 AM - Lamar/Gibbon
        This paper presents the development of a framework that enables a drone to navigate in an unknown, unstructured and GPS-denied environment. The aim of this research is to combine the use of localisation algorithms such as Simultaneous Localisation and Mapping (SLAM) with Partially Observable Markov Decision Processes (POMDP) algorithms into a framework in which the navigation and exploration tasks are modelled as sequential decision problems under uncertainty.
      • 09.0212 A Deep Reinforcement Learning Framework for UAV Navigation in Uncertain Indoor Environments. Ory Walker (Queensland University of Technology), Fernando Vanegas Alvarez (Queensland University of Technology), Luis Gonzalez (Queensland University of Technology) Presentation: Ory Walker - Wednesday, March 6th, 09:45 AM - Lamar/Gibbon
        The problem of a UAV agent searching an environment continues to be explored in the field of aerial robotics, meanwhile Deep Reinforcement Learning has grown to be powerful tool in the area of robotic control. However, while Deep RL has been applied to low level UAV control, its power has yet to be fully leveraged for the UAV search problem. This presentation presents a framework and methodology for applying deep reinforcement learning algorithms to the problem of searching an indoor environment with a UAV agent. Experimental results will be displayed using the Gazebo Simulation Platform, while challenges faced, and future improvements to be made will be discussed.
      • 09.0213 Dynamic Modeling and Controllability Analysis of a Moderately Damaged Unmanned Aerial System Aaron Mc Kinnis (University of Kansas), Shawn Keshmiri (University of Kansas) Presentation: Aaron Mc Kinnis - Wednesday, March 6th, 10:10 AM - Lamar/Gibbon
        I will first go over the methodologies for damage modeling presented in this paper. From there I will move to the controllability analysis for the case aircraft. Finally, I will briefly discuss future implementation of an ANN for the real-time control of a damaged aircraft.
      • 09.0216 Search and Retrieve with a Fully Autonomous Aerial Manipulator Kye Morton (Queensland University of Technology), Luis Gonzalez (Queensland University of Technology), Aaron Mc Fadyen (Queensland University of Technology) Presentation: Kye Morton - -
        The system presented is an autonomous multirotor-based aerial manipulator that is capable of searching an environment, visually identifying a payload, and performing a pick-and-place type maneuver. This system is aimed at implementation on low-cost hardware, and aims to provide the groundwork for the implementation of similar tree-structured aerial manipulators. The results of two separate flight tests are presented: a dynamic trajectory, used to assess the control performance of the system, and a search and retrieve task, used to assess the application of the system for payload retrieval. During the search and retrieve task, full 3D trajectories for the search stage of the flight are predefined, with the grasping maneuver generated dynamically once the payload is identified. After the operator instructs the system to begin the search pattern, the system assumes full autonomy for the remainder of the task. Once the payload is collected. the system returns to the location in which the payload is identified and awaits instructions from the operator. The manipulator and payload interactions with the multirotor base are actively compensated for by the controller to ensure stable flight during all maneuvers.
      • 09.0218 Distributed Source Seeking and Robust Obstacle Avoidance through Hybrid Gradient Descent Hannah Mohr (Virginia Polytechnic and State University), Kevin Schroeder (Virginia Tech) Presentation: Hannah Mohr - Wednesday, March 6th, 10:35 AM - Lamar/Gibbon
        This paper presents a method of source seeking for multi-agent unmanned aerial vehicle (UAV) systems in an environment with unknown obstacles. A distributed algorithm relies on localized measurements and neighbor-to-neighbor interactions to enable the group of UAVs to navigate to the location of the source. Each agent takes a scalar measurement of a signal emanating from the source, and the direction of motion is determined by estimating the gradient of the signal. The direction vector to the source is agreed upon by the agents in a coordinated manner to ensure aggregate motion toward the source of interest. Additionally, the agents avoid obstacles that are located between their initial position and the source without a priori knowledge of the number or positions of the obstacles. To ensure robust obstacle avoidance, a hybrid control method is used. The agents maintain a specified formation to improve observability during the gradient estimation process. Theoretical results for the algorithm are presented through simulation of the proposed source seeking method for a group of UAVs with single-integrator dynamics.
      • 09.0219 Multiple Ground Target Finding and Action Using UAVs Ajmal Hinas (), Roshan Ragel (University of Peradeniya), Jonathan Roberts (), Luis Gonzalez (Queensland University of Technology) Presentation: Ajmal Hinas - -
        The aim of this paper is to develop a generalized framework for vision-based multiple ground target finding and action using a low-cost UAV system. The framework can be effectively deployed on variety of UAV application with the suitable detection module in fully and supervised autonomous missions such as Search and rescue, inspection of flight debris and spot spraying application of weedicide/pesticide. The developed framework was verified using Software in the Loop (SITL) simulation and tested extensively in outdoor flight tests. Results show that the framework is capable to perform multiple target finding and action task in real-world conditions.
      • 09.0221 Haptic Feedback-based Reactive Navigation for Aerial Robots Subject to Localization Failure Shehryar Khattak (University of Nevada, Reno), Christos Papachristos (University of Nevada, Reno), Kostas Alexis (Univeristy of Nevada, Reno) Presentation: Shehryar Khattak - Tuesday, March 5th, 08:30 AM - Lamar/Gibbon
        This work presents a bioinspired alternative approach for resilient and collision-tolerant micro aerial vehicle flight, which relies on a force sensing array of antennae integrated perimetrically to the robot's body, as well as on baseline proprioceptive sensing devices such as an inertial measurement unit and a barometric sensor. This synthesis addresses cases of severely sensing-degraded environments (e.g. smoke-filled tunnels, dust--filled mines) where exteroceptive sensing such as visual cameras and LiDAR cannot function. A reactive control scheme is used to complete the proposed strategy, and experimental studies conducted in a confined environment are used to demonstrate its utility.
      • 09.0222 Development of a Multipurpose Hydro Environmental Tool Using Swarms, UAV and USV Rodrigo Rangel (BRVANT / BRV UAV & Flight Systems) Presentation: Rodrigo Rangel - Tuesday, March 5th, 08:55 AM - Lamar/Gibbon
        This paper describe the development of a multipurpose hydro environmental tool to monitor the rivers and Dams, and check the health of these places in terms of water quality and the level of siltation. In Brazil the Dams are used to supply water and generate electricity to the population. The monitoring of water resources is very important to check the degradation indices of the areas and maintain the health of rivers and reservoirs, in the actual days, the current monitoring process has been proved inefficient, due to the lack of financial resources in face of the size of the areas to be monitored. Our proposal is an alternative tool, using Aerial (UAV) and Aquatic (USV) Drones, working together to get information about the water quality, depth of rivers and Dams, and Aerial pictures of these areas. The Aerial Drone is a quadcopter with an embedded computer able to process some actions and control the payload (Smart Drone concept), has a dedicated payload able to take high-resolution pictures, using EO and multispectral camera. In some cases, the Drone can be used as communication relay to increase the operational range of the Aquatic Drone. The Aquatic Drone is an Unmanned Surface Vehicle, composed by a catamaran boat, equipped with an embedded computer, sensors and specific payload able to collect and measure the water quality. Using a specific GPS-RTK and an underwater sonar, in real time can measure the depth of the rivers and Dams. Both Drones can perform the mission in an automatic way, via pre-defined mission waypoint, created by the operator, but due the dynamic scenario of rivers and Dams, in same cases the system shall be operated in manual mode. The Quadcopters are used to mapping the Dams and rivers before the use of USV, after the flight is created a mosaic of these areas and the operator can check the actual scenario to use the USV, in this case is very common the agglomeration of aquatic macrophytes, water pollution and other obstacles. Considering the geographic and relief conditions, the Quadcopter is used as communication relay to guarantee the LOS condition and increase the operational range of USV system. In addition, the quadcopter can be used as Aerial camera to see and to control the USV, in real time. The communication between the USV and Aerial drone is performed in real time, and in automatic mode the Quadcopter can follow the USV and control it. Due the Dams size, more than one Aerial Drone or USV system can be used to mapping the areas, in this case the Swarm concept is applied to do the management of the Drones. The use of both systems together will result in a complete map of these regions (surface and underwater), using a GIS software it is possible merge theses information in an unique multilayer map that will be very useful to the authorities check the real health of our water resources in Brazil.
      • 09.0224 An Area-decomposition Based Approach for Cooperative Search and Coverage Mission of UAVs Ali Karimoddini (), Vinh K (North Carolina A&T State University), Solomon Gebreyohannes (North Carolina A&T State University) Presentation: Ali Karimoddini - Tuesday, March 5th, 09:20 AM - Lamar/Gibbon
        This paper develops a low-computation area-decomposition based approach for tasking and planning for a team of Unmanned Aerial Vehicles (UAVs) involved in a search mission. For an area of interest captured as a convex polygon, a minimum bounding rectangle is calculated and decomposed into several partitions, which are assigned to different UAVs based on their flying and sensing capabilities. A novel Mixed Integer Linear Programming (MILP) based technique is developed to automatically task the UAVs to sweep the area of interest. If each individual UAV follows the created sweeping pattern and visit the generated waypoints, applying the developed method, it can be guaranteed that the entire area of interest is searched. The developed algorithm is applied to tasking and coordination of multiple UAVs searching an area on a farm and the implementation details and results are provided.
      • 09.0227 Rollocopter: An Energy-Aware Hybrid Aerial-Ground Mobility for Extreme Terrains Sahand Sabet (), David Elliott (Cornell University), Ali Agha (), Andrea Tagliabue () Presentation: Andrea Tagliabue - Monday, March 4th, 08:30 AM - Lamar/Gibbon
        In this work, we design and model a new hybrid aerial-ground mobility system for extreme terrains referred to as Rollocopter. The platform uses common multi-rotor propellers enclosed in a spherical shell to produce the necessary forces to roll on the ground and fly. The proposed platform is able to achieve (a) multi-modal locomotion (fly and roll) for increased energy efficiency, (b) collision resiliency due to its impact-resistant structure, and (c) high-level of controllability due to three-dimensional actuation. This work focuses on the preliminary design trade-offs, analysis and feasibility assessment of the platform. First, a dynamic model of the robot that considers interaction with the ground is developed. Second, a control architecture for flying and rolling is proposed and evaluated in simulation. Finally, a discussion on the energy efficiency of the flying and rolling mobility modes via leveraging a derived dynamic model of the power consumption is provided. It was shown that the Rolling mode could significantly improve the efficiency of the vehicle specifically on low speeds.
      • 09.0228 Autonomy of Heterogeneous Agents in the Distributed Multi-Robot Task Allocation (MRTA) Problem Christopher Covert (Stanford University) Presentation: Christopher Covert - Monday, March 4th, 08:55 AM - Lamar/Gibbon
        This paper presents a simple and scalable algorithm that expands upon existing work in the field of Multi-Robot Task Allocation (MRTA). The primary purpose of MRTA is dedicated to the various methods of assigning a network of mobile sensing robots to a set of tasks in order to complete them as quickly and efficiently as possible. This paper considers the problem of heterogeneity, where robots have varying capabilities and tasks have varying requirements which adds to the complexity of robot-task compatibility to the decision making process. The novelty in this work, however, is not the focus of the decision-making framework, but the use of an implicit coverage algorithm for passive agents in the field via Voronoi partitioning. In this work, a utility-based algorithm is implemented with respect to both proximity and compatibility of the robot to the task in order to minimize distance traveled and assignment duration for each agent. To verify hypotheses posed in this work, both algorithmic development and simulated results are shown for both homogeneous and heterogeneous systems; hardware testing has yet to be conducted. While the MRTA approach provided is simplistic, idle agents (those without allocated tasks) fall into a centroidal Voronoi cell holding pattern to create passive coverage control. As a result, the algorithm presented in this work is shown to not only be both scalable and distributed, but the model is robust to changes in various tunable parameters such as number of robots and task in the environment and how much weight is designated to likeness over range.
      • 09.0229 Adaptable UAV Swarm Autonomy and Formation Platform Roxanna Pakkar (NASA Jet Propulsion Lab), Divya Srivastava (Georgia Institute of Technology), Austin Langrehr (Jet Propulsion Laboratory), Chaska Yamane (NASA Jet Propulsion Lab) Presentation: Roxanna Pakkar - Monday, March 4th, 09:20 AM - Lamar/Gibbon
        This ongoing study delves into an autonomous swarm of unmanned aerial vehicles (UAVs) that takes mission requirements and moves in formations based on user input. We utilize commercial off-the-shelf (COTS) hardware and open source software to create a low-cost accessible platform for the potential use in commercial and research applications. The system is scalable, with the capability of swarm formation in both static and dynamic configurations using real-time path planning and optimized target assignment. The group of UAVs used in this study consists of multiple quadcopters, each equipped with an on-board computer, a flight controller, and COTS telemetry and GPS modules. Commands are sent to the swarm via a ground station. The ground station and UAVs communicate via a WiFi datalink. The system has demonstrated path-planning with collision avoidance capabilities through simulations. This study shows via simulation and partially through experimentation that swarm autonomy can be implemented effectively and cost efficiently. This creates an ease of access for the use of a swarm of UAVs for a variety of applications including 3D mapping, and search and rescue across a variety of terrains with increasing difficulty.
      • 09.0231 Accurate Ground Impact Footprints and Probabilistic Maps for Risk Analysis of UAV Missions Baptiste Levasseur (ONERA), Sylvain Bertrand (ONERA), Nicolas Raballand (ONERA), Flavien Viguier (Altametris), Gregoire Goussu (Altametris) Presentation: Baptiste Levasseur - Monday, March 4th, 09:45 AM - Lamar/Gibbon
        Disposing of methods enabling to compute accurate predictions of ground impacts, both in terms of footprints and probability maps, is of a paramount importance for risk analysis of UAV missions such as Long Range Operations (eg. railways or power lines inspection). Such methods can be used offline for mission preparation and flight authorizations, or online for decision making and reactive trajectory planning (eg. choice of an emergency landing site or activation of a flight termination system). This paper investigates the problem of impact footprints and probabilistic maps computation for different failure modes of a fixed-wing UAV. Most of the works of the literature consider only simplified descent models (ballistic, gliding) in the case of engine failure. Some of them have also proposed to integrate stochastic parameters in the models to derive ground impact probability maps. Other studies have developed more realistic descent models by considering the whole dynamics of an UAV but without considering uncertainties propagation and therefore without being able to generate probabilistic ground impact maps. This paper presents a method that combines accurate dynamic models to the stochastic approach for ground risk mapping, by considering realistic and probabilistic failures modes. This method is based on the use of a complete dynamic model of a fixed-wing UAV, including aerodynamics of the vehicle and taking into account wind conditions parametrized in terms of magnitude and direction. Two parameters are used to represent different trajectory primitives and flight modes of the UAV: the flight path angle and the turning rate. This low dimensional parametrization is used instead of the whole state vector of the UAV dynamic model, enabling to reduce complexity. Probability distributions of these two parameters have been derived, for different flight modes, based on real flight data recorded during operational flights performed by Altametris, subsidiary of SNCF, the French National Railways Company. Two failure modes are considered in the paper: - Engine failure (no thrust) and control surfaces stuck to their trim positions, - Engine failure (no thrust) and control surfaces with flapping behavior randomly distributed around their trim positions. For both failure modes, and taking into account the aforementioned distributions of the flight path angle and turning rate parameters, probability maps of the ground impact points are generated using a Monte Carlo sampling method. This generation is performed to cover all the possible characteristics of a mission based on different flight modes and wind conditions. In this way, a parametrized dataset of accurate probability maps is available and can be interpolated to compute probability maps adapted to a specific given operational trajectory. This is used to assess the risk level along a planned trajectory, which can be integrated into the mission preparation process. A case study is presented in the paper based on a real flight trajectory. For online use purposes, surrogate models based on neural networks have also been developed and are presented in this paper, for the first failure mode, to enable fast generation of accurate ground impact footprints.
      • 09.0234 History-Aware Free Space Detection for Efficient Autonomous Exploration Using Aerial Robots Ryan Fite (Colorado School of Mines), Shehryar Khattak (University of Nevada, Reno), Kostas Alexis (Univeristy of Nevada, Reno), David Feil Seifer (University of Nevada, Reno) Presentation: Ryan Fite - Monday, March 4th, 10:10 AM - Lamar/Gibbon
        In this work, we present an approach for the detection of the direction of free space in order to improve the efficiency of robotic exploration by exploiting the history of free space calculations. As a motivational example, we consider the case of exploration of subterranean environments where the length of corridors can exceed the range of most sensors, multi-branched geometry may lead to ambiguity with respect to the most efficient direction of exploration, or sensor degradation can shorten the effective depth range. The proposed method can be used to assist a path planner by determining the directions of probable free space for efficient exploration. The algorithm was evaluated using point clouds from two types of sensors, namely sparse long-range sensors such as a LiDAR and dense short-range sensors such as direct depth RGBD sensors. Furthermore, evaluation took place against a variety of environments using handheld and aerial robotic data in urban and subterranean environments. During each of the tests, the algorithm has shown to be capable of consistently and reliably finding the directions of probable unobserved free space in real-time. As a final evaluation step, the proposed algorithm was integrated as part of the path planning functionality on-board an autonomous aerial robot and the relevant mine exploration field results are shown. Analysis of computational efficiency is further presented.
      • 09.0235 Design Analysis of a New On-Board Computer for the LAICAnSat Platform Ana Carolina De Melo (UnB), Fernando Guimaraes (Universidade de Brasilia), Yago Honda (Universidade de Brasilia), Renato Borges (Universidade de Brasilia), Sandro Haddad (University of Brasilia), Simone Battistini (Universidade de Brasilia), Chantal Cappelletti (Universidade de Brasília) Presentation: Ana Carolina De Melo - -
        The present work describes the new requirements for LAICAnSat project, a high altitude platform (HAP) developed at University of Brasilia (UnB). An analysis of previous missions and a detailed comparison with respect to the previous OBC version is presented to assist with the design decision making. More specifically, a study of mission lifecycle is conducted to evaluate power consumption and a survey is carried out in order to estimate new power demands.
      • 09.0236 Real-time 3D Wind Field Prediction Onboard UAVs for Safe Flight in Complex Terrain Philipp Oettershagen (Swiss Federal Institute of Technology Zurich (ETH Zurich)) Presentation: Philipp Oettershagen - Monday, March 4th, 10:35 AM - Lamar/Gibbon
        Due to a lack of environment awareness, today's low-altitude fixed-wing Unmanned Aerial Vehicles (UAVs) are limited to primitively follow user-defined waypoints. All high-level decision making is still performed by a human user. Fully-autonomous remote missions in complex environments however require true environment awareness both with respect to terrain and wind. While terrain-aware navigation is covered in existing literature, the real-time estimation and consideration of complex wind patterns onboard UAVs is not. This paper therefore presents the literature's first-ever local 3D wind field prediction method which can run in real time onboard a UAV. The selected method is a simple downscaling approach which retrieves low-resolution data from global weather models and then adjusts the wind field via potential flow theory such that terrain boundaries, mass conservation, and the atmospheric stratification are observed. Typical 3D wind fields of 1km^3 volume are calculated in below 10 seconds. Synthetic test cases such as the flow around a semi-cylinder, through a valley and over a ramp yield good results. A comparison with 3D LIDAR wind data collected over 10 days in the Swiss Alps shows an overall wind error reduction of 23% with respect to the zero-wind assumption that is mostly used for UAV path planning today. Overall, our initial research demonstrates the feasibility of real-time 3D wind field prediction onboard a UAV. However, the focus on low computation time means that the vertical wind prediction lacks accuracy. The paper therefore ends with a research outlook into real-time 3D wind field prediction through the fusion of machine learning techniques with CFD methods.
      • 09.0237 Icing Detection for Small Fixed Wing UAVs Using Inflight Aerodynamic Coefficient Estimation Andreas Wenz (Norwegian University of Science and Technology (NTNU)), Tor Johansen (Norwegian University of Science and Technology) Presentation: Andreas Wenz - Monday, March 4th, 11:00 AM - Lamar/Gibbon
        The paper presents an approach to in-flight icing detection for small fixed wing UAVs. When flying in cold and humid environments icing is a major hinderance to UAV operations. The resulting increased drag and increased risk of stalling, decreases both safety and performance. In this work a Moving Horizon Estimator, which combines aerodynamic, kinematic and stochastic wind models with data from a typical autopilot sensor suite to estimate angle of attack and lift coefficients. FENSAP icing simulations show that in severe icing conditions, both the offset and the gradient of the lift coefficient change. Based on these icing simulations an UAV flight simulator that can simulate icing has been used. Simulation results show that the MHE is capable of monitoring changes in offset and gradient of the lift coefficient due to icing. A faster convergence to the estimated coefficient values could be achieved when using an external trigger signal, i.e. from a temperature and humidity sensor, to reset the covariance matrix of the arrival cost. We also investigate the effect on convergence speed resulting from an altitude change giving additional excitation. The estimation results show angle of attack estimation errors below 1 degree. These estimates can be used to limit the angle of attack and adjust the commanded airspeed in the autopilot in order to avoid stall.
      • 09.0239 Trajectory Generation and Regeneration for Constrained Differentially Flat Control Systems Seyed Erfan Seyed Roghani (Istanbul Technical University ), Emre Koyuncu (Istanbul Technical University), Mevlut Uzun (Istanbul Technical University) Presentation: Mevlut Uzun - Tuesday, March 5th, 11:00 AM - Lamar/Gibbon
        In this study, differential flatness principle is applied in real time flight trajectory generation. This principle allows formulating the desired output trajectory through B-spline parameterization. Integrating these methodologies with sequential quadratic programming, an optimal feasible trajectory that meets all the given and dynamical limits, is generated. Through this fashion, it is guaranteed to generate dynamically feasible trajectories passing, as closely as possible, by given waypoints which guide the vehicle to track its intent. For the simulation purpose, this methodology is applied to two underactuated vehicle models (quadrotors and Dubins’ airplanes) and their maneuverability for a given mission is compared to show the validity of the integrated methodologies. While the majority of similar methodologies focus on an uninformed search for a dynamically feasible trajectory through an outer checking loop, the methodology provided in this paper benefits from a guided search for a feasible solution that an optimization algorithm provides. The advantage of this study over the ones that do benefit from an optimization algorithm is that the constraints on key dynamical states of the vehicles are strictly considered in a continuous manner instead of sampling hypersurfaces. To do so, the geometrical feature of the B-splines is utilized and the constraints are checked at times in which the dynamical state of interest reaches to an extremum. This way, the constraints do not necessarily have to be linear or representable with polynomials. In this work, it is shown that these critical times are roots of polynomials with unique sets of coefficients. Moreover, the local property of B-splines is utilized for instantaneous regeneration of the trajectory without distorting the entire path and the continuity when the vehicle needs a rapid update in trajectory plan or collision avoidance. Through the knot insertion algorithm, it is shown that it is always possible to design a new trajectory that deviates from the old one before the vehicle reaches the deviation point.
      • 09.0240 Mission-Responsive, On-Demand 3D Printed Blimps for Martian Missions Andrew Jones (North Dakota Sate University), Jeremy Straub (North Dakota State University) Presentation: Andrew Jones - Tuesday, March 5th, 09:45 AM - Lamar/Gibbon
        Rover-based exploration of Mars is inherently limited by the time-consuming process of surface movement. Even traveling constantly at maximum speed (which is logistically impossible), each rover is only be able to explore a small fraction of the planet. Orbital and aerial survey missions provide a partial solution to this, allowing larger areas to be assessed; however, a follow-up rover mission is then needed to collect samples, higher quality imagery and other data for interesting areas. To overcome this, this paper proposes to deploy autonomous blimps in the Martian atmosphere to provide a highly mobile aerial sensing platform. These blimps would also have onboard 3D printing units that are able to produce other smaller blimps for lower-altitude aerial data collection and landing to collect samples. In this paper, a high-level design for a blimp system with an aerial platform that can 3D print smaller blimps and its use to perform missions on Mars is presented and assessed. A framework for the blimp control decision-making system, including decision making about when a smaller blimp should be produced and its configuration, is proposed. Prospective missions for the system, such as surface observation or landing to take a soil sample, are discussed and used to evaluate the efficacy of the design and decision-making system. The paper concludes with a discussion of current technical limitations to the proposed drone system and mission and a discussion of the pathway to getting the technology ready for mission use.
      • 09.0241 Performance of Variable Pitch Propeller for Longitudinal Control in an Agile Fixed-Wing UAV Sajith K K (Indian Institute of Technology Bombay) Presentation: Sajith K K - Tuesday, March 5th, 10:10 AM - Lamar/Gibbon
        This paper carries out a simulation based study on the performance of longitudinal control in an agile fixed-wing UAV with variable pitch propeller (VPP). Transition between cruise level flight at angle of attack (AOA) = 4deg, and harrier level flight at AOA = 50deg is implemented, on a variable pitch propeller design, in which the pitch of the propeller is actuated to change thrust, at constant rotations per minute (RPM). In a conventional design, the thrust is changed by varying RPM which is actuated by a Brush-less DC (BLDC) motor whereas in a VPP design, the propeller pitch is actuated by a servo motor which has faster response compared to a BLDC motor used in small UAVs. Hence the thrust change is achieved faster using variable pitch actuation. A longitudinal model of an agile fixed-wing UAV which includes propwash, wing downwash, flat plate post-stall aerodynamics and actuator constraints (first order dynamics, saturation and rate limit) is used in the work. The model of a variable pitch propeller is developed from the data of a particular propeller motor combination obtained from a software named QPROP. The longitudinal control used is a backstepping based nonlinear control. The simulation results are compared with that of a conventional design in which the same flight regime with the nonlinear control is implemented . The advantages of VPP based design are observed to be faster settling of velocity, AOA and pitch rate during transitions, very small altitude variation and reduction in maximum pitch rate during cruise to harrier transition. However, an increase in maximum pitch rate during harrier to cruise transition is a disadvantage. But overall, the simulation results shows that VPP design performs better than a conventional design for the above mentioned flight regime and indicates that a VPP based design of fixed-wing agile UAVs would be better for control in agile and high AOA maneuvers like perching, transition to hover and aggressive maneuvers. However, flight testing is essential to conclude this fully.
      • 09.0242 Effects of 3D Antenna Radiation and Two-Hop Relaying on Optimal UAV Trajectory in Cellular Networks Md Moin Uddin Chowdhury (North Carolina State University), Ismail Guvenc () Presentation: Ismail Guvenc - Tuesday, March 5th, 10:35 AM - Lamar/Gibbon
        In this paper, considering an interference limited in-band downlink cellular network, we study the effects of scheduling criteria, mobility constraints, path loss models, backhaul constraints, and 3D antenna radiation pattern on trajectory optimization problem of an unmanned aerial vehicle (UAV). In particular, we consider a UAV that is tasked to travel between two locations within a given amount of time (e.g., for delivery or surveillance purposes), and we consider that such a UAV can be used to improve cellular connectivity of mobile users by serving as a relay for the terrestrial network. As the optimization problem is hard to solve numerically, we explore the dynamic programming (DP) technique for finding the optimum UAV trajectory. We utilize capacity and coverage performance of the terrestrial network while studying all the effects of different techniques and phenomenon. Extensive simulations show that the maximum sum-rate trajectory provides the best per user capacity whereas, the optimal proportional fair (PF) rate trajectory provides higher coverage probability than the other two. Since, the generated trajectories are infeasible for the UAV to follow exactly as it can not take sharp turns due to kinematic constraints, we generate smooth trajectory using Bezier curves. Our results show that the cellular capacity using the Bezier curves is close to the capacity observed when using the optimal trajectories.
    • 09.03 Aircraft Systems & Avionics Andrew Lynch (Naval Air Systems Command) & John Ennis (USMC)
      • 09.0301 ELECTROMAGNETIC Environmental Effects on Aural Warning Systems in AIRCRAFT James Lee (Boeing Company) Presentation: James Lee - -
        Aural warning systems play a critical role for the safety of commercial and military airplanes. Due to their potential susceptibility to electromagnetic interferences (EMI) and indirect lightning effects in the flight deck, regulatory agencies impose stringent electromagnetic requirements for the aural warning systems. Because the EMI and lightning risks on Aural systems are of safety concern, governmental agencies require aircraft manufacturers to evaluate and mitigate the hazardous effects of EMI and lightning occurrences in aircraft. In order to have commercial transportation aircraft be qualified and certified, airplane manufacturers must prove that the design and performance of aural warning systems meet the safety and regulatory specifications. Typical regulatory EMI and lightning requirements include RTCA DO-160 and MIL-STD-461. Aural warning systems present unique features to researchers since both audio and radio frequencies are utilized for their functionality. This means the pass and fail criteria for aural warning systems are far more complex than those of systems that utilize only the radio frequency. The purpose of this paper is to present and discuss the unique issues and test methods related to the aural warning system evaluation to achieve the necessary high quality and meet the regulatory requirements. In Section 1, we introduce the nature and function of aural warning systems. In Section 2, we discuss the standard risk modeling of evaluation parameters. Then we present the radiated and conducted susceptibility of the aural warning systems in Section 3. In Section 4 we present the lightning susceptibility for the aural warning systems. We conclude, in Section 5, with a summary and suggestions for the future work of EMI and lightning protection for aural warning systems.
      • 09.0302 ELECTROSTATIC Discharges and Grounding for AIRCRAFT James Lee (Boeing Company) Presentation: James Lee - -
        Personnel safety could be compromised when people come into contact with precipitation static (P-static) on aircraft. Also electrostatic discharge by people on sensitive electronic devices in aircraft may damage the devices. Aircraft engineers should be on guard to protect passengers, staff and maintenance crew from the hazardous effects of electrostatic discharges due to P-static. Also, engineers should produce adequate electrostatic rules to protect aircraft electronics as maintenance crew come into contact with sensitive electronic devices. Application of electromagnetics (EM) knowledge is required to study these effects and take proper protective measures. These seemingly diverse effects are in actuality the same effect when analyzed with EM physics. Thus we treat these seemingly diverse effects with the same principle. Typical methods to reduce or eliminate these effects include grounding and bonding of aircraft, aircraft equipment, electronic devices, and workers working on and around electronic equipment. In this paper, we address the methods and guidance (1) to protect passengers and staff and to reduce the risk of being harmed from the electrostatic discharge effects at aircraft surface, which are sometimes called P-static, and (2) to protect the electrostatic discharge sensitive (ESDS) devices. In Section 1, we present electrostatic energy transfer diagrams to illustrate the issues and to establish the fundamental principle. In Section 2, we present the simple risk model which aids to resolve the risks and impacts. Then P-static and electrostatic discharges (ESD) are discussed for scenarios of personnel safety and fuel tanks using several public domain documents in Section 3. We examine ESD for aircraft electronic devices in Section 4, where we also discuss the lightning safety aspect. We conclude with a summary and suggestions for the future work for the aircraft P-static and ESD topics.
      • 09.0309 Static Aeroelastic Characteristics of Grid Structure Wing Lina Qiao (Northwestern Polytechnical University) Presentation: Lina Qiao - -
        Several types of grid structure of high-aspect-ratio wing are designed basing on the idea of bionic structure. The static aeroelastic characteristics of the wings of rectangular, polygonal and curve-edged rhombic grid structures are calculated and compared, using finite element models coupled with vortex lattice method. Structural results show that the stiffness of the high-aspect-ratio wings can be improved and the weight will be reduced when the configurations, distributions and curvatures of the grids are properly selected and optimized. The rhombic grid structure has the maximum stiffness among these different grid structures. Despite the high bending stiffness, the grid structure wing has lower torsional stiffness, optimizations in detail are required. Investigations in this paper can inspire the design of lightweight high-aspect-ratio wings.
      • 09.0310 Regarding Pilot Usage of Display Technologies for Improving Awareness of Aircraft System States Taumi Daniels (NASA - Langley Research Center), Emory Evans () Presentation: Taumi Daniels - Friday, March 8th, 09:20 AM - Cheyenne
        Avionics-related systems and the procedures for interacting with them appear to be growing in complexity. This trend places a larger burden on pilots to manage increasing amounts of information and to understand system interactions. The result is an increase in the likelihood of loss of airplane state awareness (ASA). One way to gain more insight into this issue is through experimentation using objective measures of visual behavior. This study summarizes an analysis of oculometer data obtained during a high-fidelity flight simulation study that included a variety of complex pilot-system interactions that occur in current flight decks, as well as several planned for the next generation air transportation system. The study was comprised of various scenarios designed to induce low and high energy aircraft states coupled with other emulated causal factors in recent accidents. Three different display technologies were evaluated in this recent pilot-in-the-loop study conducted at NASA Langley Research Center. These technologies include a stall recovery guidance algorithm and display concept, an enhanced airspeed control indication of when the automation is no longer actively controlling airspeed, and enhanced synoptic diagrams with corresponding simplified electronic interactive checklists. Multiple data analyses were performed to understand how the 26 participating airline pilots were observing ASA-related information provided during different stages of flights and in response to specific events within these stages. In summary, this analysis is intended to provide insight into how pilots apply visual attention during complex and often off-nominal situations where loss of airplane state awareness can manifest. While oculometer data alone cannot tell the complete story, it can provide important and objective clues. Several of these are presented in this paper. Subsequent AIME studies are planned to build on the insights obtained here and through analyses of other data, to evaluate new systems that can mitigate potential vulnerabilities in an age of increasingly autonomous and complex systems.
    • 09.04 Air Vehicle Flight Controls Christopher Elliott (Lockheed Martin Aeronautics Company and University of Texas at Arlington) & Tom Mc Ateer (NAVAIR)
      • 09.0401 Adaptive Nonlinear PID Control for a Quadrotor UAV Using Particle Swarm Optimization Babak Salamat ( Alpen-Adria-Universität ), Andrea Tonello (University of Klagenfurt) Presentation: Babak Salamat - -
        We present a non-linear PID control strategy for a quadrotor helicopter. To increase the performance, the automatic adjustable integral action is integrated into the non-linear controller. Then, the control gains are optimized adaptively by using an efficient technique called multiobjective particle swarm optimization.
      • 09.0402 Robust Adaptive Dynamic Inversion with L1 Control Variable Error Regulation Christopher Elliott (Lockheed Martin Aeronautics Company and University of Texas at Arlington) Presentation: Christopher Elliott - Monday, March 4th, 09:00 PM - Gallatin
        Dynamic inversion (DI) is a special case of input-output feedback linearization and in the class of model referenced control (MRC) architectures where high-fidelity on-board models for aircraft aerodynamics, propulsion, and mass properties are required to successfully transform the closed loop system from a nonlinear to linear design problem. A well published issue with DI is the lack of robustness with the method due to this sensitivity in on-board model error, potentially leading to the onset of residual and undesirable dynamics. This paper explores L1 adaptive augmentation with a minimally invasive approach to a baseline dynamic inversion flight control system, by casting control variable error regulation as an additional high rate loop. Robustness linear analysis results are presented for the Innovative Control Effectors (ICE) tailless fighter aircraft where relative stability is characterized using minimum singular values of the return difference and stability robustness transfer function matrices for the multi-input multi-output system.
      • 09.0404 Robust Hierarchical Quad-Rotorcraft Control-Design and Stability Analysis Ranjan Dasgupta (TCS) Presentation: Ranjan Dasgupta - -
        Dynamic response and performance of a quad-rotorcraft is influenced mostly by first order drag-like effects over a wide envelope of operating conditions, however, they are hard to model. A robust controller is designed to achieve satisfactory tracking performance in the presence of drag effects considering them as nonlinear model uncertainties in the dynamics. Majority of the work on robust stabilization is for fully actuated attitude and altitude subsystem where the coupling between position and attitude systems is not considered rigorously using Lyapunov based stability analysis. Ensuring robust stability of the overall (position and attitude) underactuated system considering drag effects is a challenge. A popular strategy is to use first order sliding mode control to restrain first-order drag forces where the chattering effect, caused due to discontinuous control effort, is mitigated by adaptive sliding mode action. Robust high gain observers are used to estimate unknown perturbation that opposes the motion of the vehicle. Higher order sliding mode controller is designed to achieve asymptotic tracking without any observer or adaptive updates. Few works achieve robust stability and tracking by proposing a nominal controller for the overall system with a robust compensator. The proposed work is a hierarchical nonlinear robust control design that uses Euler-Lagrange (E-L) dynamics to compute guidance and control laws simultaneously. The underactuated E-L model considers generalized forces and torques along with drag force and torque models, which are non-smooth nonlinearities but norm-bounded. The position and attitude control laws are designed with matched and unmatched state dependent model uncertainties for the cascade system to ensure that the origin of the overall error dynamics is asymptotically converging to an ultimate bound. Using Lyapunov analysis sufficient gain conditions are strategically derived to ensure stability. The size of the ultimate bound can be arbitrarily reduced by control system parameters.
      • 09.0405 Design Studies to Achieve Energy Optimal Attitude for a Solar Powered Aircraft Vijay Shankar Dwivedi (IIT Kanpur), Salahudden Qazi (Indian Institute of Technology Kanpur), Ajoy Ghosh (), Gopalakrishna Kamath (Indian Institute of Technology) Presentation: Vijay Shankar Dwivedi - Monday, March 4th, 09:25 PM - Gallatin
        For a given flight condition if the position of the sun is taken into consideration and the attitude of the aircraft decided accordingly, more solar energy can be harvested. Changing the attitude of the aircraft changes the lift vector. As a result, the aircraft demands more power to maintain lift as the drag increases (either angle of attack is increased, or the velocity is increased). Hence there will be a trade-off between power required and solar power gained, and this trade-off will lead us towards an optimum roll angle for a level flight depending upon the intensity and position of the sun as well as flight conditions. This paper represents the theoretical representations of energy optimum attitude of a solar-powered aircraft. A controller is designed to achieve this attitude of aircraft with optimal control input. A mathematical model is used to estimate azimuth and elevation and hence the solar irradiance condition for given geographical location. Power required for a level and an unbanked flight is analytically estimated and validated from flight data. With the help of this power required, the power required for banked flight is estimated, that is utilized for optimal bank angle calculation. A case study is done for a flight from city Kanpur to New Delhi in India assuming clear sky and no wind conditions. Irradiance conditions are taken for March 20th and takeoff time is 9 AM, +5:30 GMT. The controller is designed for a low altitude long endurance solar-powered aircraft MARAAL. The MARAAL has been developed in the UAV laboratory, Indian Institute of Technology, Kanpur. This methodology can be adapted for any solar-powered aircraft, for all geographical locations and any season of the year for a clear sky day. Although this methodology is implemented here for level flight, it can be extended for climb and descent as well. For energy optimal attitude the roll angle shouldn’t very large as larger roll angle will lead to higher lift requirement resulting more power and therefore more power penalty to maintain lift. As the roll angle is not large, it can be assumed that the aircraft response to control surface input is linear for small deflections. For controller design, the aircraft dynamics is linearized about a level trim condition, and PID controller is used for roll control. It is observed, for a given aircraft and irradiance conditions, either endurance of the flight can be increased or time of flight between two places we can be reduced. While changing the attitude, it is also observed, rolling the aircraft to gain more solar power is only advantageous while sun rays are oblique enough either from left or right of flight path. For subtropical countries like India, this methodology is beneficial for solar-powered flights.
      • 09.0409 Development and Prototyping of an Altitude Control System for the LAICAnSat Platform. Yago Honda (Universidade de Brasilia), Ana Carolina De Melo (UnB), Renato Borges (Universidade de Brasilia), Simone Battistini (Universidade de Brasilia), Chantal Cappelletti (Universidade de Brasília), Matheus Alves (Universidade de Brasília), Manuel Barcelos Júnior () Presentation: Yago Honda - -
        This work aims to improve the control subsystem integrated into the LAICAnSat platform, specifically altitude and landing control system. The LAICAnSat is a project that engages students and researchers from several engineering fields, such as aerospace, mechatronics and electrical engineering, to ensure the development of a low cost modular platform for high and low altitude scientific and remote sensing services and applications using the design standard of CubeSats. The problem considered in this paper is related with the development of a modular platform able to perform long fluctuation at high altitude through a regulation system equipped with a valve for automatic release of Helium gas. The proposed altitude control system may also be explored in order to allow the quick return of the platform from the stratosphere. The proposal consists of building a valve that contains a Helium-releasing actuator and a sensor that can measure the temperature and pressure inside the balloon. In this framework, by using a proportional–integral–derivative controller (PID controller), the goal is to control the maximum altitude for the mission, as well as to analyze the possibility of performing a controlled landing by deflating the balloon. The development of the first prototype of the valve and some preliminary tests are presented and discussed.
      • 09.0410 Baseline Flight Control System Design for an Unmanned Flutter Demonstrator Daniel Ossmann (German Aerospace Center - DLR), Tamás Luspay (MTA-SZTAKI), Balint Vanek (MTA SZTAKI) Presentation: Daniel Ossmann - Monday, March 4th, 09:50 PM - Gallatin
        A comprehensive design of the baseline control and navigation system for a single-jet-engined flutter demonstrator aircraft is presented in this talk. To facilitate the design task, a classical cascaded flight control structure is selected. Advanced robust control techniques are used to design and tune the individual feedback loops of the control system. Therefore, the design problems are posted as multi-objective non-linear optimization problems which are solved using non-smooth optimization techniques. The developed control system enables augmented and fully automated flights. The availability of a high-fidelity non-linear simulator allows the assessment of the flight controller performance and robustness. The control system is verified in realistic simulation scenarios along the test pattern defined for the real flight test campaign.
      • 09.0411 Optimization of Roll Angle in Coordinated Level Turn Flight and Its Analytical Validation for UAV Vijay Shankar Dwivedi (IIT Kanpur), Salahudden Qazi (Indian Institute of Technology Kanpur), Ajoy Ghosh () Presentation: Vijay Shankar Dwivedi - Sunday, March 3th, 09:00 PM - Cheyenne
        • Optimization is performed for the computation of optimum roll angle for a coordinated level turn flight condition using numerical implementation of gradient descent approach for a fixed wing Air vehicle. • The optimum value of roll angle in coordinated turn flight has found by minimizing the cost function which was designed by current state derivatives and required state derivatives. • Throughout the analysis, the optimization closely works for Microlight air vehicle (MAV) and Unmanned air vehicle (UAV). • The optimization was carried out for two types of Aircraft which categories as microlight Air vehicle(MAV) and unmanned Air vehicle(UAV). • Simulation results were validated analytically for both microlight Air vehicle and unmanned Air vehicle for the variation of roll angle with the velocity for a given turn radius. • The validation was performed for fixed turn radii varying from twenty meters to hundred meters including infinite turn radius in straight and steady level flight using standard level turn methods.
      • 09.0413 Trajectory Control of a Swashplate-less Coaxial Helicopter Using Nonlinear Techniques Thanakorn Khamvilai (Georgia Institute of Technology), John Mains (), Michael Miller (Georgia Tech Research Institute), Eric Feron (Georgia Institute of Technology) Presentation: Thanakorn Khamvilai - Sunday, March 3th, 09:25 PM - Cheyenne
        This presentation addresses the modeling and controller design of a swashplate-less coaxial helicopter with a center-of-gravity variation mechanism. The moving-mass system is used to decouple the control moments from the propulsion system. The mathematical model is thoroughly derived to capture the interaction between the dynamics of the vehicle and of the moving-mass mechanism. Furthermore, based on this model, the nonlinear controller that guarantees the exponential tracking between the system and any arbitrary trajectory is developed. This controller is designed using the geometric approach, which allows the system to be considered separately as a few subsystems. The coupling effects between these subsystems are shown to be bounded, which preserve the stability of the overall system. Two simulation trials, in which this controller is implemented, demonstrate the stability.
      • 09.0415 Longitudinal Control of an Agile Fixed-Wing UAV Using Backstepping Sajith K K (Indian Institute of Technology Bombay) Presentation: Sajith K K - Sunday, March 3th, 09:50 PM - Cheyenne
        In this paper, a nonlinear backstepping based longitudinal control is applied to an agile fixed-wing unmanned aerial vehicle (UAV) to achieve transitioning between level flight at low angle of attack (cruise) and level flight at high angle of attack (harrier level) and the performance is compared with a gain scheduled state feedback control. In all flight regimes, the elevator control law is computed using backstepping control strategy designed for error dynamics in pitch and pitch rate. During transition from cruise to harrier flight, the propeller rotations per minute (RPM) is calculated using an additional Lyapunov based nonlinear control which stabilizes the error dynamics in flight path angle to zero. During cruise and harrier level, the respective trim value of RPM is applied and during transition from harrier to cruise the trim value corresponding to cruise is applied. Simulations of the control implemented on a longitudinal model of an agile fixed-wing UAV which includes propwash, wing downwash, flat plate post-stall aerodynamics and actuator constraints (first order dynamics, saturation and rate limit) to achieve the flight objective, are done using Matlab 9.4 . Compared to gain scheduled state feedback control, the advantages of the nonlinear control strategy are: 1) less altitude loss and oscillations in velocity and pitch angle during harrier to cruise transition, 2) reduction of around 60 % in maximum pitch rate during both transitions and 3) less chattering during both transitions. However, significant increase in computational complexity is a disadvantage. Overall, a preliminary assessment can be made that the nonlinear control strategy is better than the gain scheduled state feedback control for achieving the specific flight regime and could be advantageous in high angle of attack (AOA) maneuvers like perching, transition to hover and aggressive maneuvers.
  • 10 Software and Computing Kristin Wortman (Johns Hopkins University Applied Physics Laboratory) & Sanda Mandutianu (Jet Propulsion Laboratory)
    • 10.01 Computational Modeling Virgil Adumitroaie (Jet Propulsion Laboratory) & Darrell Terry (The Mitre Corporation)
      • 10.0103 DESIGN Space Reduction Using Clustering in Aircraft Engine DESIGN Esma Karagoz (Georgia Institute of Technology), Darshan Sarojini (Georgia Institute of Technology), Jimmy Tai (Georgia Institute of Technology), Dimitri Mavris (Georgia Institute of Technology) Presentation: Esma Karagoz - Monday, March 4th, 04:55 PM - Gallatin
        The presentation will start with an introduction about the importance of Design Space Exploration (DSE) studies in the early stages of engineering design. This introduction will include a discussion about how the dimensionality in engineering design can be high and how the parametric DSE methodologies can be helpful to have a better understanding of the trends and tradeoffs in the design space. Then, the computational expense of evaluating high dimensional design space will be discussed. A solution to reduce the computational burden will be provided which is the design space reduction methodology developed in the paper. This methodology will be explained in detail, including how the input and output design space is obtained, how the clustering algorithms are applied to the output space, and how the truth model is obtained for verification purposes, etc. Also, the conceptual design of a turbofan engine is explained since it is chosen as the use case. Finally, the efficiency of the proposed methodology will be discussed and some statistics about how much design space reduction can be obtained through different clustering algorithms will be presented. In addition, how this design reduction methodology can be helpful for optimization algorithms will be discussed.
      • 10.0110 Dynamic Equivalent Load Simulation with Smart Actuators Venkatesh B (RV College of Engineering), Chandra Prakash (R V College of Engineering), Promio F (R V College of Engineering), Gowtham Reddy (RVCE) Presentation: Venkatesh B - -
        Smart actuator has been gaining momentum as a replacement to conventional actuator due its light weight, optimal rigidity, high performance actuation and low complexity in manufacturing and functioning. This paper presents in detail a prevue of problems arising in this area. Smart actuator is the one which acts both as sensor and as well as actuator. In this current work we deal with the use of Micro Fiber Composite (MFC) of different dimensions and properties in arriving at the given task. The deflections of certain mode shapes of MFC are of keen importance in practical applicability i.e. Wing Morphing and Stiffening of Structures, precision valve actuation, health monitoring. The present work emphasizes on the use of smart actuator in studying both the static and dynamic characteristics of the given cantilever plate structure. In order to understand the structural behavior, it is essential to understand the capability and response of the MFC alone, and later the effect of MFC bonded on the structure was studied. The influence of input voltage on MFC is studied and the dynamic equivalent load simulation using smart actuator is presented. Structural displacements are validated for both mechanical loading and equivalent forcing voltage .Loads of dynamic nature such as sinusoidal nature and linear loads are applied and the results are to be matched with their respective voltage deflections .To achieve this, the scale factor was computed and the same was used in validating for different loading conditions. This paper presents in detail the complete procedure to obtain the scale factor in extracting exact results that can be practically experimented on a real time structural problem
      • 10.0111 A Study of Jovian Magnetic Field Derived Parameters for Synchrotron Radiation Modeling Virgil Adumitroaie (Jet Propulsion Laboratory) Presentation: Virgil Adumitroaie - Monday, March 4th, 05:20 PM - Gallatin
        The Juno spacecraft arrived at Jupiter July 4, 2016 and is now in a 53.5-day polar orbit. Synchrotron radiation generated by ultra-relativistic electrons trapped in Jupiter’s magnetosphere is detected and measured by the MWR Radiometer over a range of wavelengths from 2 cm to 50 cm. An extension of the Levin et al. (2001) multi-zonal, multi-parameter model to simulate synchrotron emission using assumed electron distributions and Jovian magnetic field models (VIP4 and the latest incarnation, JRM09) generates the four Stokes parameters of the synchrotron emission. The model depends on magnetic-field-derived quantities such as L-shell and B critical, the minimum magnetic field amplitude for a given L-shell at which electrons that mirror at or below the upper boundary of the atmosphere are lost. This study describes the modeling issues associated with aforementioned derived parameters and results for VIP4 and JRM09 models.
    • 10.02 Innovative Software Engineering and Management Techniques and Practices Ronnie Killough (Southwest Research Institute) & Nigel Tzeng (Johns Hopkins University Applied Physics Laboratory) & Kristin Wortman (Johns Hopkins University Applied Physics Laboratory)
      • 10.0201 Analytics and Insights about Cultivating a Software Engineering Community at DLR Tobias Schlauch (DLR), Carina Haupt (German Aerospace Center - DLR), Michael Meinel (German Aerospace Center (DLR)), Andreas Schreiber (German Aerospace Center (DLR)) Presentation: Carina Haupt - Sunday, March 3th, 04:30 PM - Lake/Canyon
        Software development increasingly became part of the daily work of many researchers in science and engineering. They are faced with software engineering challenges for which they are not trained. In 2005, the German Aerospace Center (DLR) started the “DLR Software Engineering Initiative” to support their researchers addressing these challenges. A core element of the initiative is to setup and establish an active software engineering community. Improving the activities of the DLR software engineering initiative is an on-going challenge. For this purpose, a good understanding of the software engineering community within DLR is required. In this paper, we want to presents insights about the DLR software engineering community by analyzing the participants of the annual software engineering knowledge exchange workshops. These workshops can be considered as the annual software engineering community event and offer therefore a good starting point to analyze the community. First, we characterize software development at DLR to illustrate the context and the specifics of an aerospace research organization. We introduce the concept of the knowledge exchange workshops, which we conducted at various sites of DLR in the past years. Then, we describe the specific research questions and explain our analysis approach. Finally, we present the results as well as discuss their implications and indicate future directions.
      • 10.0202 Maximizing Software Production & Quality with Minimum Staff Using Clarity – a Real-World Case Study Rob Thorpe (Southwest Research Institute) Presentation: Rob Thorpe - Sunday, March 3th, 04:55 PM - Lake/Canyon
        Developing software in today’s world can be a challenging activity. Demand for software engineers is high, software development continues to be an activity fraught with potential risk, and maintenance challenges are expanding as software languages grow in complexity, supporting code libraries multiply, and software engineers move between companies. The Space Data Systems (SDS) software engineering organization at Southwest Research Institute produced 33 production software products for NASA and ESA space exploration and research missions over a 20-year period with a staff averaging 6 software engineers and testers. The Clarity software engineering process was created during this time, focusing specifically on maximizing software production and quality with minimum staff. With Clarity, SDS raised its average effectiveness for the past six years to 95%, meaning that SDS spent 95% of its time creating new functions or expanding existing functions, as opposed to fixing bugs. Clarity maximizes software staff effectiveness by implementing enough process by the right person at the right time to minimize software rework - the “Goldilocks” approach to software process management. Through a system of product-independent checklists and forms, Clarity focuses on mitigating error propagation through the software lifecycle process, leveraging the Software Lead as the process executor, and leaving software developers and testers to do what they do best - produce quality software products.
      • 10.0203 Worst-Case Measurement-Based Statistical Tool Pavel Zaykov (), Jan Kubalčík (Honeywell International) Presentation: Pavel Zaykov - Sunday, March 3th, 09:00 PM - Lake/Canyon
        In this paper, we address the problem of computing the worst-case timing bound for avionic applications executed on a Commercial-Of-The-Shelf (COTS) multi-core processors from the embedded domain by estimating the application Worst-Case Execution Time (WCET). We analyze the existing state-of-the-art approaches for the estimation of application worst-case timing bounds and outline their limitations. Based on the identified gap analysis, we propose a WOrst-case Measurement-Based stAtistical Tool (WOMBAT) using the Extreme Value Theory (EVT). As an input, WOMBAT employs traces from the application execution time traces and the probability of exceedance defined by the Design Assurance Level (DAL). As an output, WOMBAT estimates the WCET. WOMBAT is a stand-alone tool, and it relies on the user to correctly configure the experimental setup. We experiment with execution time traces from real and synthetic applications executed on an embedded COTS multi-core processor. The purpose of the experiments is to demonstrate the applicability of the proposed statistical approach.
      • 10.0204 DevOps for Planetary Defense Flight Software Christopher Heistand (Johns Hopkins Univ Applied Physics Lab (JHU APL)), Justin Thomas (The Johns Hopkins University Applied Physics Laboratory), Nigel Tzeng (Johns Hopkins University Applied Physics Laboratory), Luis Rodriguez (Johns Hopkins University/Applied Physics Laboratory) Presentation: Christopher Heistand - Sunday, March 3th, 05:20 PM - Lake/Canyon
        The NASA Double Asteroid Redirection Test (DART) mission, led by the Johns Hopkins University Applied Physics Laboratory (JHU/APL), will be the first ever space mission to demonstrate asteroid deflection by a kinetic impactor. The DART flight software team recognizes that meeting this challenge, especially within cost and schedule constraints, requires us to enhance our software practices with a strong DevOps methodology. DevOps (development operations) fuses software development and operations to form a tight feedback loop during software construction and release deployment. We have established and implemented a DevOps architecture that has already benefited the DART mission, including successful integration testing with the DART NEXT-C electric propulsion system. The cornerstone of our DevOps architecture is a Software-In-The-Loop (SWIL) environment that acts as a “spacecraft on a laptop”, providing a personal development and test environment. The SWIL environment also enables multiple "spacecraft" instances to be stamped out for our scalable, highly-parallel, Continuous Integration (CI) automated test program. Our development cycle has changed drastically from a manual, human-based testing approach for each major release to an automated one that runs each time the software baseline is updated. We built upon our CI approach to enable Continuous Delivery (CD) allowing us to deploy the latest flight software to our Hardware-In-The-Loop (HWIL) testbeds with a button click. We are on target to achieve our goal of a successful simulated asteroid impact each and every night, using both our SWIL and HWIL environments. This SWIL environment has also already served as the platform for integration testing with DART's electric propulsion system: the NASA Glenn Research Center NEXT-C engine. These tests use a standard off-the-shelf laptop to run flight software, testbed/emulation software, and ground system software to exercise the NEXT-C engine prior to the availability of all flight avionics. Throughout these tests, we are able to incrementally increase system fidelity from software-only emulations to flight hardware without making leaps in the software. There are several key enablers vital to achieving our DevOps architecture: Vagrant for work environment configuration, Docker for software containerization, the NASA Core Flight System for an underlying platform abstraction, Ball Aerospace’s COSMOS ground system, the Linux operating system, much of the Atlassian tool suite, and both the Klocwork and CodeSonar static analysis tools. These tools represent a cross-section of modern embedded and web-based software development in a way that benefits spacecraft flight software. This presentation will introduce the DART mission, discuss DevOps and the philosophy as it applies to spacecraft flight software development, illustrate our DevOps architecture and walk the audience through each major component, detail the resulting successful NEXT-C test campaign, and finally, provide lessons learned from our transition to this approach.
    • 10.03 Software Architecture and Design Sanda Mandutianu (Jet Propulsion Laboratory) & Martin Stelzer (German Aerospace Center (DLR))
      • 10.0302 Visualization of Software Architectures in Virtual Reality and Augmented Reality Andreas Schreiber (German Aerospace Center (DLR)), Lisa Nafeie (German Aerospace Center - DLR), Artur Baranowski (), Peter Seipel (German Aerospace Center - DLR), Martin Misiak (University of Applied Sciences TH Köln) Presentation: Lisa Nafeie - Wednesday, March 6th, 09:50 PM - Dunraven
        Software architecture is abstract and intangible. Tools for visualizing software architecture can help to comprehend the implemented architecture but they need an effective and feasible visual metaphor, which maps all relevant aspects of a software architecture and fits all types of software. We present the visualization of component-based software architectures in Virtual Reality (VR) and Augmented Reality (AR). We describe how to get all relevant data for the visualization by data mining on the whole source tree and on source code level of OSGi-based projects. The data is stored in a graph database for further analysis and visualization. The software visualization uses an island metaphor, which represents every module as a distinct island. The whole island is displayed in the confines of a virtual table, where users can explore the software visualization on multiple levels of granularity by performing navigational tasks. Our approach allows users to get a first overview about the complexity of an OSGi-based software system by interactively exploring its modules as well as the dependencies between them.
    • 10.04 Software Quality, Reliability and Safety Engineering Kristin Wortman (Johns Hopkins University Applied Physics Laboratory) & Paul Wood (Southwest Research Institute)
      • 10.0402 Day to Day Practices to Enhance Operations Reliability for Magnetospheric Multiscale Paul Wood (Southwest Research Institute), Patrick Smith (University of Colorado Boulder) Presentation: Paul Wood - Thursday, March 7th, 09:00 PM - Cheyenne
        The Magnetospheric Multiscale (MMS) mission consists of a cluster of four satellites with many instruments including several high voltage instruments. The day to day operations plan must account for instrument safety concerns, cluster maneuvers to maintain high quality data collection while at the same time maintaining fleet safety, data collection management to optimize the potential for high quality data acquisition, and data file management to bring down the maximum amount of high quality data within the MMS downlink allocation. Development of the daily fleet Absolute Time Sequence (ATS) is critical to safe and reliable operations, requiring a high degree of coordination between the operations and instrument teams. Instruments have unique requirements and tools and techniques have been developed to accomplish reliable generation of the ATS on a weekly basis. We describe our experiences in working to improve reliability for MMS operations.
      • 10.0403 Planning for Change in Instrument Flight Software: Successes and Failures on MMS HPCA Paul Wood (Southwest Research Institute), Judith Furman (Southwest Research Institute) Presentation: Paul Wood - Thursday, March 7th, 04:55 PM - Cheyenne
        Instrument Flight Software Developers face challenges when designing for operations. On the one hand, a highly flexible and reconfigurable system can permit adaptation on orbit without the need to develop, validate, and update software on orbit. On the other hand, projects are limited in budget and schedule, and predicting future needs for requirements that are not currently in scope may be untenable. We discuss our experiences with the Magnetospheric Multiscale Hot Plasma Composition Analyzer software development.
      • 10.0404 Eliminating Software Caused Mission Failures Michael Dorin (University of St. Thomas) Presentation: Michael Dorin - Thursday, March 7th, 05:20 PM - Cheyenne
        The availability of common off the shelf components, as well as the ability for multiple satellites to share a launch vehicle, has dramatically reduced the cost of putting a satellite into space. Many satellites are built, but many of these satellites fail to meet their objectives. Often, a satellite’s failure is caused by a problem outside the control of a design team. However, in some cases, the failure is caused by human error, and software failures are a likely candidate for human error. Software problems in a satellite application can mean an enormous loss of invested time and money. In this research, programmers of all skill levels were surveyed to identify the characteristics and implications of complicated software. After analysis of the surveys, an effort was made to identify whether programs with characteristics of being complicated contained more faults or required more effort to maintain. Software from multiple open source repositories was reviewed including an estimation of effort based on bug reports and bug discussions. Results from this analysis show that complicated programs do require more effort and are more problematic. This study finds that complicated software causes more errors and that such software errors can be avoided by conscientiously developing uncomplicated code.
      • 10.0406 Agile Approach to Assuring Safety-critical Embedded Software for NASA’s Orion Spacecraft Justin Smith (NASA Independent Verification & Validation ), John Bradbury (Engility Corporation), Will Hayes (Carnegie Mellon University), Wesley Deadrick (NASA - Goddard Space Flight Center) Presentation: John Bradbury - Thursday, March 7th, 04:30 PM - Cheyenne
        Human-rated missions like those in NASA’s Orion Program continue to grow in complexity. The role of software in achieving ambitious mission objectives has expanded dramatically in the last few decades. Assuring the safety and performance of the embedded flight software is quickly growing beyond the reach of traditional methods and resource levels. The methods used to build these software-dominant systems evolve in an on-going attempt to keep pace with the scope of our ambitions. Agile software development is now commonplace. The long timelines and large batches of work associated with traditional methods are being replaced by rapid delivery of small increments – as system capabilities are realized in waves. Assurance of these critical software capabilities must therefore conquer an ever-expanding frontier of challenges, and do so with an approach matched to the evolving development methods. This paper recounts the journey of the Orion Independent Verification and Validation (IV&V) team as we addressed this dynamic environment. Widening our aperture to encompass a dramatically larger mission scope, while adjusting our cadence to synchronize with the rapid pace of agile software development, a new approach to IV&V is emerging. This approach is characterized by a sharper focus on mission capabilities, matched with a method to dynamically ‘follow the risk’ as the IV&V team delivers more compelling assurance data in waves. Traditional methods prevalent in IV&V tend to scope the work using artifacts of the development process as they evolve from preliminary to final versions, and the pace of delivery was synchronized with the development timelines prevalent in the waterfall lifecycle. That more static approach is out of phase with the demands of the new environment. Scoping work according to the critical capabilities of the system (rather than artifacts of development) and synchronizing with the rapid pace of agile development, we are moving toward more effective parity with the demands of the environment. We explain the concrete steps we took, the principles that motivated our choices, and the results we have achieved to date. Keywords: Capability Based Assurance, Agile IV&V, Incremental Risk Assessment
      • 10.0407 Visualization Method to Stimulate Ideas Leading to Failure Mode in Software FMEA Kohsuke Namihira (Japan Aerospace eXploration Agency, JAXA), Naoko Okubo (), Sho Kurahayashi (Japan Aerospace Exploration Agency) Presentation: Kohsuke Namihira - Thursday, March 7th, 09:25 PM - Cheyenne
        Failure Modes and Effects Analysis (FMEA) for software-intensive systems (called software FMEA in this paper) requires the ingenuity of engineers to set failure modes because software itself never fails as hardware does with physical phenomena. Successful software FMEA allows the experience, knowledge, identification of appropriate items and guide words to be integrated in the engineer’s mind. Therefore, software FMEA could be considered a somewhat imaginative activity that largely depends on the engineer’s competence. In the space domain, there tends to be less experience on software FMEA as compared to other domains having a shorter development cycle. In addition, the limited concrete knowledge about an unknown system and its environment under operation tends to limit the ideas for analysis when a single engineer performs software FMEA. As a result, we sometimes experienced software FMEA activity that had a negligible effect on the subsequent development phase. To resolve this issue, analysis and review by several engineers are adopted as a solution to cover the lack of experience and competence by an individual. Team reviews are generally useful to expand the idea to lead failure modes. However, a team review may offer a biased result when applying an ad hoc method such as brainstorming. To avoid a biased result, revealing the thinking process and discussion points can help guide proper discussion and also add various ideas from several engineers. Therefore, we proposed a novel method of visualizing the thinking process that led to failure modes by extending Goal Structuring Notation (GSN). Team members will be expected to stimulate ideas by looking at artifacts that visualized the scope of failure mode. Any missing item or possible failure mode can thus be discussed, allowing team members to easily add ideas for the analysis. The team review with the proposed method successfully identified meaningful failure modes in a development project at the Japan Aerospace Exploration Agency (JAXA). Moreover, failure mode and its end effects analysis led by the proposed method contributed not only to software design but also to software testing for setting test cases of adverse conditions.
    • 10.05 Model-based Systems and Software Engineering Oleg Sindiy (Jet Propulsion Laboratory) & Alexander Murray (Jet Propulsion Laboratory)
      • 10.0502 Assuring Correctness, Completeness, and Performance for Model-Based Fault Diagnosis Systems Allen Nikora (Jet Propulsion Laboratory, California Institute of Technology), Priyanka Srivastava (NASA Jet Propulsion Lab), Lorraine Fesq (Jet Propulsion Laboratory), Seung Chung (Jet Propulsion Laboratory), Ksenia Kolcio Prather (Okean Solutions, Inc), Maurice Prather (Okean Solutions, Inc.) Presentation: Allen Nikora - Monday, March 4th, 04:30 PM - Cheyenne
        The robotic scientific and commercial spacecraft industries are currently trending towards the development of onboard autonomous capabilities for responding quickly to dynamic environments and rapidly changing situations. Model-based fault diagnosis (MBFD) is an approach to estimating a spacecraft’s health state by continuously verifying accurate behavior and diagnosing off-nominal behavior. Proper functioning of MBFD depends on 1) the quality of the diagnostic system model that is analyzed and compared to commands and onboard measurements to estimate a system’s health state, and 2) the correct functionality of the diagnosis engine interrogating the model and comparing its analyses to observed system behavior. Our goal is to develop Verification and Validation (V&V) techniques for a MBFD system to provide the necessary confidence in its ability to estimate the health of on-board spacecraft components and systems accurately and precisely. Our effort is investigating two areas. First, we build on our previously-reported work in developing techniques for checking the correctness and completeness of MBFD systems. Second, we develop techniques for analyzing performance characteristics of MBFD systems (e.g., runtime, memory usage) to provide assurance that they will function within the resource-constrained environments found on spacecraft. This paper describes work we have done in both areas. For the first area, we describe our approach to developing formal definitions for a correct and complete fault diagnosis system, the application of those definitions to a systematic way of checking the correctness and completeness of a diagnostic model independently from the diagnosis engine, and the results of these checks. We also discuss the ways in which V&V techniques are related to our correctness and completeness checking techniques for a MBFD system development process. For the second area, we develop analytical expressions as functions of key parameters to estimate runtime/processing performance bounds. In parallel, we define various model structures (topologies) to enable parameterized testing to determine how specific parameters affect performance, providing a way to identify the significant contributors. These analyses lay the foundation for developing techniques and tests for evaluating false-positive and false-negative metrics, which are used to characterize MBFD diagnosis performance.
      • 10.0504 MBSE Infusion and Modernization Initiative (MIAMI): “Hot” Benefits for Real NASA Applications Jon Holladay (NASA), Karen Weiland (NASA Glenn Research Center), Jessica Knizhnik (NASA Goddard Space Flight Center), Amanda Stein (NASA), Terry Sanders (Jacobs Technology) Presentation: Jon Holladay - Monday, March 4th, 08:55 AM - Cheyenne
        Two years of learning, alignment, and application of Model Based Systems Engineering towards complex NASA missions has resulted in over a dozen concrete use cases that illustrate the benefits of a digital framework for systems engineering. The MBSE Pathfinder informed the plans to move NASA towards enterprise implementation of MBSE. Examples in which both quantitative and qualitative benefits were obtained are provided. The first example shows how systems engineering models used for concept design and definition were re-used for verification and test for a rocket engine. Schedule metrics were tracked to determine the improvement when using MBSE compared to recent historical data from manual methods. The second example shows the seamless transfer of modeling elements and data between the systems engineering model, computer aided design model, loads analysis, and additive manufacturing software for a payload adapter. This example shows how MBSE can be used to validate concepts and perform rapid prototyping. Qualitative benefits include improved communications and customer satisfaction. These examples, and others in a rich portfolio of results, demonstrate benefits available at points across the entire lifecycle in a rapid, agile approach. The MBSE Pathfinder projects were set up deliberately to sample multiple points in the lifecycle to understand the nuances and requirements sooner, rather than following one project end-to-end. The results from the MBSE Pathfinder help define the infrastructure and requirements necessary for a future systems engineering capability and provide a guide towards a full-up, integrated approach to systems development. To organize and implement these goals, the MBSE Pathfinder expanded into the MBSE Infusion and Modernization Initiative (MIAMI). The approach as well as the structure of MIAMI is unique in that it relies on learning from the use of MBSE on real projects and capturing the benefits that are useful for working engineers to make systems engineering easier. The lessons from this work are available for use by those who are interested in learning from or partnering with MIAMI.
      • 10.0505 A Model-Based Systems Engineering Approach to Exploration Medical System Development Andrea Hanson (NASA Johnson Space Center), Jennifer Mindock (KBRwyle), Melinda Hailey (KBRwyle / NASA), Kerry Mc Guire (NASA - Johnson Space Center), Jorge Bardina (NASA Ames Research Center), Bill Toscano (NASA - Ames Research Center), Sean Winther (NASA - Ames Research Center), David Rubin (KBRwyle), Jeff Cerro (NASA - Langley Research Center), Mena Abdelmelek (), Alexander Rubin (), Mikayla Kockler (KBRwyle), Kris Lehnhardt (NASA - Johnson Space Center) Presentation: Jennifer Mindock - Monday, March 4th, 09:20 AM - Cheyenne
        The work presented in this paper describes how NASA’s Human Research Program’s (HRP) Exploration Medical Capability (ExMC) Element has adopted Systems Engineering principles and tools (Model-Based System Engineering (MBSE) and the Systems Modeling Language (SysML),) to develop an initial architecture and requirements for a future exploration medical system. The paper describes the utility and effectiveness of the model and the derived products. Using MBSE tools, medical needs are translated through the clinical domain to the engineering community to inform the future lunar Gateway mission architecture.
      • 10.0506 From Cocktail Napkin to Concept Feasibility: Spacecraft Design in Early Formulation with TATER Kristina Hogstrom (), Jonathan Murphy (Jet Propulsion Laboratory) Presentation: Kristina Hogstrom - Monday, March 4th, 09:45 AM - Cheyenne
        The Innovation Foundry at NASA’s Jet Propulsion Laboratory (JPL) is developing a new tool for rapid design, tradespace evaluation, and feasibility assessment of planetary science mission concepts in the earliest stages of formulation. The Tool for Architectural Tradespace Exploration and Refinement, or “TATER”, will encompass a broad set of analyses covering the driving factors needed to describe and compare concepts, from trajectories and technologies to cost and risk assessment and science value. At the core of TATER is a spacecraft design model suite, which allows a single user to design a self-consistent spacecraft with limited information. TATER estimates mass, power, and cost at the subsystem level, key design metrics that can be used to assess a concept’s likelihood of meeting requirements. Thus, TATER provides users with a quantified basis for comparing design options early in the concept maturity timeline, so that the most promising options can be identified and selected for further development. This presentation will be a high-level introduction to TATER, with an overview of the architecture, examples of empirical and physics-based sizing models, and demonstrations of using the tool and converging to a design solution. The presentation will also include results from a validation study, which demonstrated that TATER is ready for use in preliminary concept feasibility assessments.
      • 10.0508 New Methodology for Model Based Safety Analysis Akram Abdellatif (Technical University of Munich) Presentation: Akram Abdellatif - -
        The presentation introduces a new methodology of Model-Based Safety Analysis (MBSA). MBSA is an approach in which the system and safety engineers share a common system model created using a model based development process. There are two famous approaches for the addition of fault behaviors to system models. The first one is to enclose the model of failures into the system design directly. The second approach is to develop a fault model separately from the system model; thus combining both independent models for safety analysis. The new approach will combines three concepts: failure modes, directed graph traversal, event lists. A prototype tool is developed upon object oriented paradigm. The tool shall be tested on various systems. The results will be analyzed; advantages/disadvantages will be represented.
      • 10.0510 Early Validation of the Data Handling Unit of a Spacecraft Using MBSE Joe Gregory (University of Bristol), Lucy Berthoud (University of Bristol), Theo Tryfonas (University of Bristol), Antonio Prezzavento (Airbus DS Ltd) Presentation: Joe Gregory - Monday, March 4th, 10:10 AM - Cheyenne
        Model-Based Systems Engineering (MBSE) represents a move away from the traditional approach of Document-Based Systems Engineering (DBSE), and is used to promote consistency, communication, clarity and maintainability within systems engineering projects. MBSE offers approaches that can address issues associated with cost, complexity and safety. Focus groups with Airbus spacecraft functional avionics engineers have highlighted that one way this can be achieved is by performing early functional validation of the high-level spacecraft functional avionics system. This paper defines an approach to the application of MBSE to perform early functional validation of a spacecraft. This approach acts as an extension to a methodology in development by Airbus. It focusses on the definition of the Concept of Operations during Phase B. Information traditionally contained in a Mission Operations Concept Document is presented through a Mission Operations Concept Model. The aim is to improve the clarity, consistency and quality of the information being communicated by providing a model template to contain the relevant system information and enable the high-level simulation of the design. This high-level simulation is enabled by the execution of static systems engineering diagrams. The mission phases are defined and a mission profile, determined by the orbit characteristics, specifies the duration of each phase. The system mode diagram details the response of the system to a change in the mission phase, and activity diagrams describe the functions that must be performed by the system in each mode. Executing this information allows the response of the system to be analysed and validated against high-level mission needs. Traditionally, this level of analysis would not be available at this early stage. The approach replaces ad hoc calculations with a formal representation of the system that can be executed, interrogated and quantified. The structure of the spacecraft system is represented by block definition and internal block diagrams, and the functionality by executable state machine and activity diagrams. Textual requirements are presented and maintained within the model and are formally linked to the physical and functional architectures. These requirements are refined by mathematical constraints that can be satisfied by calculations performed during the simulation. The use case discussed in this paper focusses on the data handling unit onboard an Earth-observation spacecraft. The system response in terms of the onboard memory usage throughout the mission is calculated. The onboard memory consists of three directories – one for housekeeping telemetry and two for science data. The simulation shows that for the chosen orbit, the total onboard memory allocation is adequate and provides a solution for the optimum memory allocation between the three directories. Ultimately, a flexible Mission Operations Concept Model template will be derived for use on future projects, which will enable them to realise the benefits demonstrated in the use case: improved control, communication and early validation of the functional avionics system design.
      • 10.0511 Constraint-Based Off-Nominal Behavior Modeling for Europa Clipper Bradley Clement (Jet Propulsion Laboratory), Anthony Zheng (), Cameron Burnett (NASA Jet Propulsion Lab), David Legg (), Michel Ingham (Jet Propulsion Laboratory), Kelli Mc Coy (NASA Jet Propulsion Lab) Presentation: Bradley Clement - Monday, March 4th, 10:35 AM - Cheyenne
        The risk analysis for the Europa Clipper mission evaluates the probability of mission failure based on the failure rates of individual components and dependencies among them. The probabilities are calculated by integrating the failure probability density functions over the intervals of time within which a fault may occur. The response of the spacecraft to different faults can result in different schedules of activities, changing both the failure probability density functions and the time intervals of integration. This paper describes an approach to generating the schedules for the different fault cases and determining the associated time intervals. In order to represent the behavior of the spacecraft using a simple, declarative syntax, we employ a language based on ontologies of behavior and scenarios. A constraint-based analysis engine uses the declarative specification to identify bounds on system parameters and fill in details of behavior. These bounds include the time windows within which certain faults can occur, which are also the bounds for integration in the calculation of failure probability. Determining these time windows is a constraint optimization problem. For an individual fault in Clipper’s propulsion subsystem, the engine is able to solve for values of the time window, but it cannot directly solve for the windows when they are functions of the times of previous faults. We used Mathematica to solve for these functions, and for more complicated scenarios, the functions are nearly too large to manage. We discuss this challenge of maintaining a closed-form calculation for more detailed fault models, and present the model of propulsion fault response behavior that illustrates the challenge. We also discuss some advantages of the behavior modeling language, comparing to a mixed integer-linear program model. Time windows are given for some of the many scenarios of interest.
      • 10.0515 NASA's MBSE Infusion and Modernization Initiative (MIAMI) Nicholas Waldram (Jet Propulsion Laboratory), Steven Cornford (Jet Propulsion Laboratory), George Plattsmier (NASA - Marshall Space Flight Center) Presentation: Nicholas Waldram - Monday, March 4th, 08:30 AM - Cheyenne
        The Model Based Systems Engineering (MBSE) Infusion and Modernization Initiative (MIAMI) is a NASA-wide effort to lay the groundwork for an integrated framework of tools and technology to advance the objectives of Systems Engineering at NASA, with emphasis on efficiency, interconnectivity, and breadth of scope. Within the MIAMI effort, the Sounding Rocket Team, led by George Plattsmier (MSFC) and George Turner (GSFC), has implemented MBSE within the domain of NASA Sounding Rocket Operations Contract (NSROC) Sounding Rocket missions, using the Systems Modeling Language (SysML) to outline system architectures, requirements, mission assurance, stakeholders, events, and deliverables. The current team effort supports the Marshall Grazing Incidence X-Ray Spectrometer (MaGIXS) experiment. The rocket team, focused on the mission planning and execution domain, is working in tandem with a MIAMI Sounding Rocket MaGIXS experiment team, focused on the experiment domain, to model the mission, systems, experiment, and interfaces to produce and deploy an integrated mission model. Through communication and coordination between NASA and the Sounding Rocket Program Office (SRPO), the MIAMI Sounding Rocket team is tailoring their pilot efforts to specific deliverables identified as critical throughout the full mission lifecycle by Nathan Empson (Mission Operations Manager) and others at SRPO. These products, as part of an overall NASA MBSE pilot effort, will enable evaluation of the utility of MBSE for sounding rocket missions. The team coordinates their work through a spiral development process punctuated by “sprints” to seam together the advancements in defining architecture and behavior of the systems involved, with the various technologies and analyses used to bolster the modeling effort. For developing technologies and modeling patterns, the team continues to interface with the Computer Aided Engineering Systems Environment (CAESE) team at JPL to explore and expand the system “model” from a MagicDraw server project to a nodal system of tools and services that delivers to stakeholders at various levels of cognizance. This environment is centered around an “authoritative source of truth”, known as the Integrated Mission Model upon which several interfaces are integrated such that users throughout all regions of the model see data, commits, updates, and structural changes in real time for a better collaboration workspace throughout the project. In the current instance of this modeling network, the Integrated Mission model uses the individual MagicDraw models for the rocket team and the experiment team, where modelers commit up to the master model, and use synchronized checkouts and updates. This allows for better version control, user permission allocation, and support for distributed work efforts to improve collaborative efficiency. The current state and future state of the team effort is to appropriate the tools and libraries available to meet the desired use-cases requested by NSROC. Throughout the process of MBSE integration, the larger goal through MIAMI is to project high-level modeling concepts and implementations into useable and tractable deliverables for small missions. Additionally, through support and development of the model as applied to MaGIXS, re-usability is achieved so that the efficiency of modeling itself is improved.
      • 10.0517 Automated Power Analysis of Onboard Spacecraft Electronics with Model Based Systems Engineering Richard Ferguson (BAE Systems), Joseph Marshall (BAE Systems) Presentation: Richard Ferguson - Monday, March 4th, 11:50 AM - Cheyenne
        This presentation discusses power consumption estimation and how Model Based Systems Engineering is able to provide a novel improvement to existing development methods. A Power Estimation Framework has been developed by BAE Systems to enable quick turn power estimation feedback during early conceptual development phases while system architectures are evolving. This Power Estimation Framework builds on SysML language constructs to provide automated simulations calculating total system power while leveraging a reusable database of components and source data.
      • 10.0518 Evaluation and Development of the OSRA Interaction Layer for Inter-Component Communication Jan Sommer (German Aerospace Center - DLR), Raghuraj Tarikere Phaniraja Setty (Elektrobit Automotive GmbH), Olaf Maibaum (German Aerospace Center - DLR), Andreas Gerndt (German Aerospace Center), Daniel Lüdtke (German Aerospace Center - DLR) Presentation: Jan Sommer - Monday, March 4th, 11:00 AM - Cheyenne
        Ever increasing demands on the complexity of onboard software has led the European Space Agency to define the Onboard Software Reference Architecture (OSRA) to create a common framework for modeling onboard software for space applications. The first major version was released at the end of 2017 and provides the metamodel with additional documentation and a model editor. It enables the user to create a detailed high-level representation of an onboard software system, but leaves the choice of an execution platform and the generation of actual source code for it to the implementing party. The core philosophy of OSRA is to divide the onboard software into independent components with clearly defined interfaces and separate the functional and non-functional aspects of components. However, OSRA aims to cover a large range of applications and therefore provides a large variety of modeling artifacts for component interaction. While this gives a lot of design freedom to the software architect designing the overall software, it moves the responsibility of supporting all aspects and behavioral requirements correctly to the execution platform and interaction layer. In this study, we analyze the demands of OSRA towards the execution platform and necessary elements which have to be added or generated in order to support the multitude of different inter-component interactions. The results of the analysis are used to implement a first prototypical code-generation framework for OSRA models. The target execution platform for the code generators is the Tasking Framework, a reactive co-operative multitasking framework from DLR. It has successful flight heritage in numerous spacecraft projects and has also been the target of code generation from software models before. Nevertheless, many of the aspects discussed here apply equally to common priority-based preemptive multitasking frameworks. The analysis and the implementation both uncovered several issues where clarification in the OSRA metamodel description was necessary. We will discuss the additional constraints we introduced towards the metamodel in order to deal with these issues, which eases the generation of code skeletons and scheduling primitives. Finally, while this study concentrates on the inter-component interactions, we will also discuss further aspects currently missing from OSRA and which either need to be added by the implementing party or in a future revision.
      • 10.0519 Research for Safety Analysis of IMA Architecture Based on HiP-HOPS Yang Yun () Presentation: Yang Yun - Monday, March 4th, 11:25 AM - Cheyenne
        This paper uses HiP-HOPS (Hierarchically Performed Hazard Origin and Propagation Studies) to solve fault propagation which is caused by integration in avionics system. The HiP-HOPS also addresses the problem of failure modes integrity, dynamic failure and data consistency which are currently encountered in safety assessments for IMA( integrated modular avionics). HiP-HOPS is based on a number of well-established techniques such as Functional Failure Analysis (FFA), hierarchical model, FMEA and FTA.FFA can identify critical functional failures of the system, in other words functional losses or malfunctions which lead to critical or catastrophic effects. And FFA can also identify common mode failures. To guarantee consistency between the analyses, all the remaining aspects of safety assessment were performed on a consistent hierarchical model of this architecture. HiP-HOPS can be used to perform IF-FMEA (Interface Focused-FMEA) and generate fault tree. IF-FMEA determines the failure modes that the component itself generates or propagates. In the course of Fault Tree Synthesis we parse the expressions contained in the IF-FMEAs of the components that we encounter during the traversal, and progressively substitute the input deviations received by each component with the corresponding output failures propagated by other components. HiP-HOPS is currently supported by a tool called HiP-HOPS tool. HiP-HOPS is applied to cabin display system in IMA for safety analysis. First we make FFA for cabin display system to find the critical failure which is the loss function of HDD(Head Down Display).Second we use HiP-HOPS tool to create the hierarchical model of cabin display system. Third a large IF-FMEA table for the failure of HDD is created. Last a complete fault tree for loss function of HDD is finally generated through the deep traversal of the IF-FMEA table with the help of HiP-HOPS tool. The results show that it not only analyzes the component failure mode caused by internal malfunction, but also analyzes the input fault generated by other components which are interfaced with the components. So the problem of fault propagation caused by the integration of IMA functions has been solved efficiently. HiP-HOPS can also make the model for dynamic failure in IMA and at the same time guarantee the consistency of its safety analysis results.
    • 10.06 Implementing Artificial Intelligence for Aerospace Christopher Bridges (Surrey Space Centre) & Jeremy Straub (North Dakota State University)
      • 10.0601 A Review of and Proposed Framework for Artificial General Intelligence Lyle Long (Penn State Univ.), Carl Cotner () Presentation: Lyle Long - Friday, March 8th, 08:30 AM - Gallatin
        This paper will review the current status of artificial general intelligence (AGI) and describe a general framework for developing these systems for autonomous systems. While AI has been around for about 70 years, almost everything that has been done to-date has been what is called “narrow” AI. That is, the theory and applications have mostly been focused on specific applications, not “strong” or general-purpose AI (or Artificial General Intelligence, AGI). As stated in [2], Deep Blue was great at playing chess but could not play checkers. The typical AI of today is basically a collection of well-known algorithms and techniques that are each good for certain applications.
      • 10.0606 Artificial Intelligence for the Early Design Phases of Space Missions Audrey Berquand (University of Strathclyde), Francesco Murdaca () Presentation: Audrey Berquand - Friday, March 8th, 08:55 AM - Gallatin
        Recent introduction of data mining methods has led to a paradigm shift in the way we can analyze space data. This presentation introduces how Artificial Intelligence (AI), and especially the field of Knowledge Representation and Reasoning (KRR), could also be successfully employed at the start of the space mission life cycle via an Expert System (ES) used as a Design Engineering Assistant (DEA). An ES is an AI-based agent used to solve complex problems in particular fields by mimicking the experts' reasoning. There are many examples of ES being successfully implemented in the aeronautical, agricultural, legal or medical fields. Applied to space mission design, and in particular, in the context of concurrent engineering sessions, an ES could serve as a knowledge engine and support the generation of the initial design inputs, provide easy and quick access to previous design decisions or push to explore new design options. Integrated to the User design environment, the DEA could become an active assistant following the design iterations and flagging model inconsistencies. The DEA project aims to enhance the productivity of experts by providing them with new insights into a large amount of data accumulated in the field of space mission design. Natural Language Processing (NLP), Machine Learning (ML), Knowledge Management (KM) and HumanMachine Interaction (HMI) methods are leveraged to develop the DEA.
      • 10.0607 Autonomous Imaging and Mapping of Small Bodies Using Deep Reinforcement Learning David Chan (University of California Berkeley), Ali Agha () Presentation: Andrea Tagliabue - Friday, March 8th, 09:20 AM - Gallatin
        The mapping and navigation around small unknown bodies continues to be an extremely interesting and exciting problem in the area of space exploration. Traditionally, the spacecraft trajectory for mapping missions is designed by human experts using hundreds of hours of human time to supervise the navigation and orbit selection process. While the current methodology has performed adequately for previous missions (such as Rosetta, Hayabusa and Deep Space), as the demands for mapping missions expand, additional autonomy during the mapping and navigation process will become necessary for mapping spacecraft. In this work we provide the framework for optimizing the autonomous imaging and mapping problem as a Partially Observable Markov Decision Process (POMDP). In addition, we introduce a new simulation environment which simulates the orbital mapping of small bodies and demonstrate that policies trained with our POMDP formulation are able to maximize map quality while autonomously selecting orbits and supervising imaging tasks. We conclude with a discussion of integrating Deep Reinforcement Learning modules with classic flight software systems, and some of the challenges that could be encountered when using Deep RL in flight-ready systems.
      • 10.0608 RULE Based System Development for Conceptual Aircraft DESIGN Esma Karagoz (Georgia Institute of Technology), Dimitri Mavris (Georgia Institute of Technology) Presentation: Esma Karagoz - Friday, March 8th, 10:10 AM - Gallatin
        The presentation will start with an introduction about how Artificial Intelligence (AI) methods can aid in the engineering design process, using the knowledge and experience from the earlier designs. In addition, an overview of how AI methods work in general, and how different types of reasoning techniques can be applied to engineering design problems will be presented. This introduction will be tied to the AI application in the paper, which is the development of a Rule-Based System (RBS) for conceptual aircraft sizing and synthesis problem. There will be motivation slides for both the RBSs and the conceptual aircraft design process to explain the general concept. Then, the implementation of the RBS in the conceptual design of commercial transport aircraft will be explained in detail. In other words, given the design requirements and specifications, how the engineering knowledge, which is represented by rules, is applied to obtain the design space will be explained. Also, how the RBS algorithm gets to the final design space and the logic behind the algorithm will be articulated. Finally, advantages and disadvantages of employing RBS in the engineering design process will be discussed, along with the additional work that will be done in the future.
      • 10.0609 Design of a Hybrid Digital-twin Flight Performance Model through Machine Learning Mevlut Uzun (Istanbul Technical University), Mustafa Demirezen (İstanbul Techical University), Emre Koyuncu (Istanbul Technical University), Gokhan Inalhan (Istanbul Technical University ) Presentation: Mevlut Uzun - Friday, March 8th, 09:45 AM - Gallatin
        This study implements deep learning techniques to estimate fuel burn of a jet aircraft. Current ground based flight planning systems utilize aircraft type specific performance tables to determine fuel flows for given flight conditions and parameters such as altitude, mass and speed. These tables are corrected by a performance factor as the aircraft ages. Despite this update, planned fuel consumption may indeed not overlap with the actual one. In order to synchronize the base aircraft model with aircraft’s actual performance, we propose using state-oft-he-art deep learning algorithms for building data-driven models of fuel flows. Towards this goal, aircraft’s on-board recorded trajectory and parameter data, namely Quick Access Recorder (QAR) data are utilized. The total dataset used within this study comprises of more than 1000 B777-300ER flights from a major European flag carrier airline. The deep neural network architecture is utilized for modeling the actual fuel flow specific to each aircraft and for each major flight mode (climb, cruise and descent namely). We have developed three neural network architectures (according to in-flight and ground based planning use cases) to present a tail-number specific correction factor to Base of Aircraft Data (BADA) models. First architecture involves a QAR data based black-box fuel flow model utilizing in-flight throttle data from all the engines. Comparison of this model with real flight data shows that precise estimation of fuel flow with mean errors lower than %0.1 can be achieved. The second architecture utilizes a physically consistent data regeneration of thrust using BADA formulation as to account for the ground planning phase where throttle information is not available. The third model involves a cascaded architecture which utilizes a neural network throttle estimator and the blackbox QAR fuel flow model for again the ground planning phase. Comparison of the latter models with real flight data shows that precise estimation of fuel flow with mean absolute errors lower than %0.7 can be achieved at all the flight modes. Finally, ground based planning fuel flow models are applied to actual flight plans generated by ground based systems. Total trip fuel comparisons show discrepancies up to %3.5 total fuel loading weight, which may result in potential fuel savings by decreasing the fuel load during take-off.
      • 10.0610 Viability of Training an Artificial Neural Network to Detect Targets Using Synthetic Data Yong Sinn (Air Force Institute of Technology) Presentation: Yong Sinn - Friday, March 8th, 10:35 AM - Gallatin
        This paper presents and solves a constrained real-world problem of using synthetic data to train artificial neural networks (ANNs) to detect unresolved moving targets in wide field of view (WFOV) infrared (IR) satellite motion imagery. Objectives include demonstrating the use of the Air Force Institute of Technology (AFIT) Sensor and Scene Emulation Tool (ASSET) as an effective tool for generating IR motion imagery representative of real WFOV sensors and describing the ANN architectures, training, and testing results obtained. A 3-dimensional convolutional network (3D ConvNet) and long short term memory (LSTM) network were used within the same pipeline to achieve the goal of IR small target detection and prediction. The 3D ConvNet was generally able to predict target locations with a mean absolute error (MAE) median of 0.31 using the temporal and spatial features of motion imagery. The LSTM predictions were based on previous target locations and incorporating the LSTM predictions to future frames resulted in a MAE median of 0.45. This paper uses a deep learning model with both convolution and LSTM components that performs well on IR small target tracking, which would otherwise be difficult to detect in individual frames.
      • 10.0614 Anti-Drone and Anti-Autonomy: Achieving Drone Control via System Logic Analysis Jeremy Straub (North Dakota State University) Presentation: Jeremy Straub - Friday, March 8th, 11:25 AM - Gallatin
        Drones (more formally known as unmanned aerial vehicles or unmanned aerial systems) are poised to provide benefits in numerous areas of society. Their application areas range from package delivery to military surveillance to scientific data collection. However, drone presence and activities are, in some cases, undesirable. Whether launched by a prankster, criminal, terrorist organization or state actor – or perhaps just an average citizen who has lost control of the craft – there is a need to prevent drone operations. This paper proposes a method that does not require physical interaction with the drone or the ability to compromise its ground control station or its onboard security or other software. Instead, the proposed method focuses on the identification of the logical processes that are used for decision making, their decomposition into rules (including rules that must be represented using partial membership and fuzzy logic) and the mapping of the rules into an expert system-style network. From this network, a solver algorithm can be utilized to identify solutions that modify external inputs (electronic data and sensed information) to produce a desired response from the UAV’s autonomous command system. These responses could include departure from a restricted area, positioning for in-air capture or targeting, landing or a targeted crash. This paper presents the proposed system, the logic-to-rule decomposition process and a solver mechanism for the rule-based system. In also discusses the implementation of the system and its testing, before concluding with a discussion of its efficacy for various applications and pathways for future work.
      • 10.0615 Multi-Sensory CNN Models for Close Proximity Satellite Operations Alaa Mazouz (Surrey Space Centre), Christopher Bridges (Surrey Space Centre) Presentation: Alaa Mazouz - Friday, March 8th, 11:50 AM - Gallatin
        We propose using a multi-sensory computer vision system that accounts for data reliability and availability using an adaptive input policy. We use custom datasets containing RGB and Depth images of a reference satellite mission for training and testing deep convolutional neural network models for object detection. Our simulation testbed generates our datasets which cover all poses, different ranges, lighting conditions and visual environments. The trained models use multi-sensory input data from both an optical sensor (RGB data) and a time of flight sensor (Depth data). The multi-sensory input data is passed through am adaptive input layer to complementarily provide the most reliable output in a harsh space environment that does not tolerate missing and unreliable data.
      • 10.0616 Self-Reconfiguring Modular Robot Learning for Lower Cost Space Applications Andrew Jones (North Dakota Sate University), Jeremy Straub (North Dakota State University) Presentation: Andrew Jones - Friday, March 8th, 01:00 PM - Gallatin
        The applications for self-reconfiguring modular robots are far reaching. Their advantage comes from their ability to form into many different shapes which allows them to perform a multitude of tasks. This is especially advantageous for space applications, due to the associated high cost of launching equipment into space. Self-reconfiguring robots are not a panacea, however. A trade-off between flexibility and capability exists. A modular robot that configures itself to do a specific task may be unable to perform as well as a robot that was designed specifically for that task. This disadvantage can be mitigated by having the units form into optimal configurations for the associated tasks. This is difficult to pre-define for tasks that are not known a-priori. To this end, the robots are designed to learn and choose the most efficient ways of reorganizing into the desired configuration. In this paper, the use of machine learning for commanding a self-reconfiguring modular robot system is investigated. A method is proposed under which the robot system would be able to learn through a trial and error process to form itself into different configurations, more optimally.
    • 10.07 Human-Systems Interaction Andreas Gerndt (German Aerospace Center) & Janki Dodiya (German Aerospace Centre) & Kilian Hoeflinger (German Aerospace Center - DLR)
      • 10.0701 Augmented Reality for Remote Collaboration in Aircraft Maintenance Tasks Sebastian Utzig (DLR), Robert Kaps (German Aerospace Center - DLR), Syed Muhammad Azeem (German Aerospace Center (DLR)), Andreas Gerndt (German Aerospace Center) Presentation: Sebastian Utzig - Thursday, March 7th, 09:00 PM - Gallatin
        We present a concept study to facilitate maintenance of an operating aircraft based on its lifelong collected data, called Digital Twin. It demonstrates a damage assessment scenario on a real aircraft component. We propose a graphical user interface that contains menu-guided instructions and inspection documentation to increase the efficiency of manual processes. Furthermore, experts located at different sites can join via a virtual session. By inspecting a 3D model of the aircraft component they can see synchronized information from a Digital Twin database. With Augmented Reality glasses, the Microsoft HoloLens, a Digital Twin can be experienced personally. In the inspector’s view, the 3D model of the Digital Twin is directly superimposed on the physical component. This Mixed Reality Vision can be used for inspection purposes. Any inspection related information can be directly attached to the component. For example, damage locations are marked by the inspector on the component’s surface and are stored in the Digital Twin database. Our scenario demonstrates how new information can be derived from the combination of collected data and analyses from the Digital Twin database. This information is used to maintain the continued airworthiness of the aircraft. Feedback from domain related engineers confirm that our interface has an enormous potential for solving current maintenance problems in the aviation industry. Additionally, our study provides ideas for the integration of further analysis functions into the interface.
      • 10.0703 The Development of a User Interface for Mixed-Initiative Plan Management for Human Space Flight Melissa Baltrusaitis (Georgia Institute of Technology), Karen Feigh (Georgia Tech) Presentation: Melissa Baltrusaitis - Thursday, March 7th, 09:25 PM - Gallatin
        The communication delay inherent in deep space travel will make relying on ground-based mission control to manage the daily lives of astronauts difficult. Thus, we are proposing the design of a mixed-initiative plan (MIP) management system to provide crews with greater autonomy in adapting plans to reflect the current state of the mission. Successful MIP systems contain a formal representation of the work, computational methods to optimize potential solutions, and a user interface for which crewmembers may interact with the schedule. This presentation will detail the creation of the user interface from requirements derivation through preliminary design.
      • 10.0706 Continued Advances in Supervised Autonomy User Interface Design for METERON SUPVIS Justin Peter Schmaus (German Aerospace Center (DLR)), Neal Lii (German Aerospace Center) Presentation: Peter Schmaus - Thursday, March 7th, 09:50 PM - Gallatin
        The exploration of the universe remains a challenging endeavor, constantly pushing the limits of technology. Of special interest is the investigation of the other planets of our solar system such as Mars, which has been examined by various teleoperated and (semi-) autonomous satellites and landers. But an important milestone that is needed for a deeper understanding of the planet is still missing: A crewed landing. In order to send humans to such a remote location, an infrastructure for the landing crew including an energy supply, a habitat, and a return vehicle needs to be provided on the surface of the planet. The construction and maintenance of these structures is envisioned to be done by semiautonomous robots that are commanded from orbiting spacecrafts. The teleoperation of such ground-based robots poses high demands on the capabilities of the system including robot autonomy, orbiter-robot communication, and human-robot interface design. The METERON SUPVIS Justin space telerobotics experiment suite has been initiated by the German Aerospace Center (DLR) together with the European Space Agency (ESA) to investigate the requirements for such a system and evaluate an approach. During the experiment sessions, astronauts onboard the International Space Station (ISS) command DLR’s humanoid service robot Rollin’ Justin on Earth to execute complex surveillance, service, and repair tasks in a simulated Martian solar farm. The robot uses its local intelligence to support the astronaut operator upon task completion allowing a simple intuitive command interface and lowering the requirements on the communication link. This work gives an overview of the developed robotic system, communication link, and tablet computer user interface (UI). In particular the tight coupling between the autonomy system of the robot and the UI, that allows the intuitive robot commanding including action parameterization, is described in detail. The first space-ground experiment sessions of METERON SUPVIS Justin were conducted in August 2017, and March 2018 by four astronauts in total. During the first session, three astronauts demonstrated the operational readiness of our system by commanding Rollin’ Justin to perform surveillance and inspection tasks. The astronauts were even able to successfully command the robot in scenarios, which were not trained prior to their spaceflight. This was possible, because our astronaut-robot collaboration concept efficiently guides the operator towards task completion. We used this property in the second experiment session to evaluate our system in even more complex scenarios. While in the first session it was sufficient for the astronaut to select the correct commands, the operator was now required to manually parameterize some of the commands to optimize the task outcome. By that, the robot has been successfully commanded to perform complex maintenance and adjustment tasks in the simulated Martian solar farm. In this work, we evaluate the preliminary results of the METERON SUPVIS Justin space-ground experiments and discuss the feedback we received from the astronauts and its impact on future space telerobotics UI design.
    • 10.08 Cloud Computing, Big Data Analytics, and Enterprise Software Related Systems Kapil Bakshi (Cisco Systems Inc)
      • 10.0802 Approaches for Using Machine Learning Algorithms with Large Label Sets for Rotorcraft Maintenance Maria Seale (USACE Engineer Research and Development Center), Nathan Rigoni (US Army AMRDEC), Luis Vega (U.S. Army Engineer Research and Development Center), Amanda Hines (ERDC), Grace Nabholz (USACE ERDC), Alicia Ruvinsky (US Army ERDC), Owen Eslinger (US Army ERDC) Presentation: Maria Seale - Wednesday, March 6th, 09:25 PM - Dunraven
        The US Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC), in collaboration with the US Army Engineer Research and Development Center (ERDC), is using machine learning (ML) to transform the way rotorcraft maintenance logbook event data is scored for reporting purposes. Traditionally, human analysts manually inspect data fields completed by maintenance personnel and, using published guidelines in conjunction with their personal expertise, provide sets of labels or scores for each event. These labels are stored with the data and provide valuable insight into maintenance event histories. However, the inequity between the enormous volume of maintenance data generated daily and the ability of analysts to score the data results in only 10% of all data receiving scores; therefore, 90% of the recorded data does not contain this important value added feature. Classification algorithms for automating this scoring process trained on existing labeled data sets have been implemented with promising results. A particularly challenging element of this problem, however, involves the classification of the specific component on which maintenance was performed. Greater than 1,200 unique labels exist that can be used to describe a rotorcraft component that is the subject of a maintenance action. Furthermore, the component labels are hierarchically structured, resulting in the occurrence of multiple levels of precision in identifying a component in the expert-labeled data used for training. Although computational efficiency of common classification algorithms has improved considerably, it is still quite challenging to harness these methods for problems that include large numbers of unique class labels. This paper describes several novel strategies for solving this problem, based on hierarchical ensemble models and strategic label set segmentation. Through these approaches, a best overall total component classification accuracy of 96% was achieved, in conjunction with a total per record accuracy for three different label categories of 93%. The approaches implemented to handle the large label set for classification of rotorcraft components, along with classification performance measures, are discussed.
  • 11 Diagnostics, Prognostics and Health Management (PHM) Wolfgang Fink (University of Arizona) & Andrew Hess (The Hess PHM Group, Inc.)
    • 11.01 PHM for Aerospace Systems, Subsystems, Components and Structures Andrew Hess (The Hess PHM Group, Inc.)
      • 11.0101 Satellite Battery Health Monitoring Using Naïve Bayesian Classifier Wessam Hussein (MTC), Mahmoud Sayed (Canadian International College), Mohamed Galal () Presentation: Wessam Hussein - Thursday, March 7th, 05:20 PM - Lamar/Gibbon
        This paper proposes a supervised Naïve Bayesian classifier to build data driven models that detect power supply system anomaly. Battery flight test data has been used as the abnormal class, representing possible failures, an approach to overcome the problem of unavailability of labeled abnormal data in a supervised classification. Data used to build the model is a three months observation of battery`s capacitance, voltage, temperature and pressure. Data has been subjected to principal component analysis before Naïve Bayesian classifier model building for visualization, labeling training data and to increase the variables independence as a restriction imposed by the naïve Bayesian classifier. The built Naïve Bayesian classifier model is validated using real faulty data in terms of accuracy, recall, precision, F1-score and ROC curve.
      • 11.0102 Consideration of Variable Operating States in a Data-Based Prognostic Algorithm Simon Mehringskötter (Technische Universität Darmstadt), Christian Preusche (TU Darmstadt) Presentation: Simon Mehringskötter - Tuesday, March 5th, 08:30 AM - Lake/Canyon
        A technical system’s availability is vital for economic efficiency. Especially, unscheduled downtime has a major impact on economic efficiency in most branches. Prognostics and health management (PHM) is an emerging discipline which enables downtime scheduling while using as most as possible of a component’s wear margin. Common approaches rely on data-based algorithms that are trained with acquired sensor data and aim to model the degradation behavior in order to predict the degradation curve as well as the remaining useful life (RUL). Most data-based approaches examine a rather static operating condition of a unit under test (UUT), i.e. the load or number of revolutions is not varied while generating run to failure data of a component like bearings. While this assumption can be held for several components, there are those that are operated in a varying state. An aircraft’s control surface actuator is an exemplary component that sees different loads through varying airspeed, weather and the flight mission. Since these variations influence the degradation behavior, they have to be considered in a prognosis algorithm. In this presentation of the underlying paper, a prognosis algorithm is proposed that incorporates a varying operating state, where an operating state is characterized by the parameters which significantly influence the degradation behavior. For a final discussion of the performance improvement, a simulated dataset is generated as input for the proposed and a reference algorithm. It is shown that the proposed algorithm achieves a better prediction performance compared to the reference algorithm that does not incorporate the varying operating state.
      • 11.0103 Uncertainty Propagation in a PHM Enhanced Dynamic Reliability Model Henrik Heier (Technische Universität Darmstadt) Presentation: Henrik Heier - Tuesday, March 5th, 08:55 AM - Lake/Canyon
        The reliability assessment of a complex system, such as an aircraft, is of major importance due to safety and economic reasons. To improve online reliability estimations, PHM is considered as a promising alternative to conventional methods, which are mostly based on static failure rates. By monitoring and predicting the future performance of individual components, the reliability assessment becomes more accurate and can adapt to true usage and wearout of a given system. To realize this, new models are required, which aggregate multiple (component specific) RUL estimations up to system level. However, as different PHM algorithms vary in their overall performance it is necessary to consider these induced PHM related uncertainties during the aggregation of the data. In this paper, an existing hybrid reliability model is extended to account for the prognostic uncertainties resulting from different PHM algorithm performances. It is further shown, how PHM performance metrics can be used as an uncertainty measure in a reliability context. In that way, the initially proposed hybrid reliability model becomes aligned within the traditional reliability assessment methodology and can be used as a decision-making support for the operation of complex systems in varying mission scenarios.
      • 11.0104 Using Machine Learning for Data-based Assessing of the Aircraft Fuel Economy Sebastian Baumann (Technische Universität Darmstadt) Presentation: Sebastian Baumann - Tuesday, March 5th, 09:20 AM - Lake/Canyon
        Weight, lift, drag and thrust are the key forces during flight influencing the consumption characteristics of an aircraft. Monitoring the aircraft's fuel consumption allows statements to be made about the aircraft performance and flight efficiency. Here, valuations with regard to a propulsive or an aerodynamic degrading as well as procedural benefits are of interest for aircraft operators and airlines. Conventional data analyses and calculation methods (ex post), e. g. via physical models or statistical metrics like median or mean, have the disadvantage of not being able to quantify influencing parameters on the fuel economy accurately enough in many cases. A more precise method, which allows statements and assessments (diagnoses based on historical flight data) and estimations (prognoses based on estimated model inputs) on the aircraft fuel consumption, would be desirable to detect aircraft fuel and flight (in)efficiencies under real flight operational and environmental conditions. In this respect, a reliable trade off would be desirable in order to avoid uneconomical modeling effort and reduce expenses concerning data procurement. This paper is in the scope of an application-oriented machine learning method development. For this reason, the present work deals with algorithms of machine learning, which can exceed current methods, especially for complex tasks with multivariate interdependencies. Ensembles of bagged decision trees for regression and classification purposes, as well as hierarchical cluster analyses applied on full flight data records from flight operations. Thus, the paper addresses two objectives and provides first approaches for: modeling of route, environment and aircraft (tail sign) specific characteristics for feasible fuel flow predictions on the one hand (diagnosis and prognosis in the field of data science); data-based analyses and quantification of influencing factors on the fuel economy to identify routes and anomalous flights on the other hand (data mining, pattern recognition). The latter, thus, aims at an improvement of reporting and the derivation of recommendations for actions for future flight profiles. Finally, the analysis capability of the concept is shown with first results for two analysis questions with three examples, evaluated based on an analysis with sample flight data provided by NASA Dashlink. To proof and evaluate the applicability of this method, a benchmark is also presented by using an available (physical) performance model and statistical metrics.
      • 11.0105 Prediction of Battery Remaining Useful Life on Board Satellites Using Logical Analysis of Data Ayman Ahmed (), Ahmed Salama (), Hussien Ibrahim (), Mohammed Abd Elfattah (), Soumaya Yacout (École Polytechnique) Presentation: Ayman Ahmed - -
        In this research, we have addressed the estimation of the remaining useful time of lithium-ion batteries on board a spacecraft. The example that is given is based on a NASA lithium ion battery dataset. We used the statistical Kaplan Meier estimator for remaining useful time calculation. We proposed to combine the Logical Analysis of Data (LAD) to the Kaplan Meier estimator to improve the estimation’s accuracy. LAD generates pattern(s) of degradation, which can be observed periodically to predict the occurrence of failure. For each failure pattern, we traced its Kaplan Meier estimated curve and, as a result, the accuracy of the failure time prediction was improved. The results show that the mean average error between the estimated remaining useful lifetime of a battery is improved by using LAD. Better accuracy is obtained by using clustering based on the maximum difference method. Since the work was done using a five fold cross validation and covers a relatively large number of batteries from the NASA dataset, the robustness of the results seems to be acceptable. The proposed method, using LAD and the Kaplan Meier estimator, provides a unique advantage, allowing for early monitoring and prediction of the failure tendency based on interpretable patterns. This result introduces LAD as an “efficient failure-pattern generator” which, in principle, could be used for onboard satellites to monitor critical systems. In future research, this work will be extended to include the effect of orbital position, battery temperature variation and satellite modes of operation (as a load change). We will also work on improving prediction accuracy at a specific cycle by automatically classifying the previously failed batteries in class 1 (short life). We will also take into consideration the degradation trend by considering the estimation of the RUL in previous cycles.
      • 11.0109 Oil System Health Management for Aerospace Gas Turbines Andrew Mills (University of Sheffield) Presentation: Andrew Mills - Tuesday, March 5th, 09:45 AM - Lake/Canyon
        This presentation reviews lubricating oil quality sensing technologies through an experimental evaluation of commercial sensors for application to gas turbine engines. A summary of the requirements gathering process to motivate the evaluation criteria will be given before operating principles are described. The presentation makes recommendations for a health monitoring sensor suite. The oil system of a gas turbine performs essential lubrication and thermal management functions, providing that the fluidic and tribological properties of the oil can meet functional requirements. New engine designs place increasing thermal and mechanical loads on the oil, and thus increase the risks of accelerated degradation potentially causing the oil properties to deviate from requirements. Presented with these risks, there is a potential business benefit for in-situ oil condition knowledge to support oil system health management. Starting with the business needs elicited from stakeholders, a Quality Functional Deployment process is performed to derive sensing system requirements. Sensing principles are reviewed for their capability to assess tribological failure mechanisms, and this is related back to stakeholder requirements. A set of sensors were procured and a testing programme performed that exercises the sensors against different degradations of oil and the noise factors representative of service. These sensors are evaluated for their ability to provide oil condition information. The framework presented in this paper uses system engineering principles to derive a health system design and verification process. The results from verification are reported to aid in providing overarching system availability management.
      • 11.0114 PHM by Using Multi-Physics System-Level Modeling and Simulation for EMAs of Liquid Rocket Engine Kaname Kawatsu (Japan Aerospace Exploration Agency) Presentation: Kaname Kawatsu - Tuesday, March 5th, 10:10 AM - Lake/Canyon
        In this presentation, results of a trial case study of model-based fault detection and diagnosis targeting to electromechanical actuators (EMAs) will be presented. The need for condition-based maintenance to improve reusable launch vehicle readiness, reliability and safety, with affordable maintenance cost and quick turnaround time is recognized. In pursuit of this goal, model-based fault detection and diagnosis procedures were developed in this study. These procedures entail the prior evaluation of the target system’s dynamic behavior under both normal and abnormal conditions by using multi-physics and system-level modeling, and a simulation technique based on a Modelica-based support simulation tool for the purpose of acquiring information for fault detection and diagnosis as time-series data. Failure detection and diagnosis are thus conducted by comparing the time-series data prepared by using normal and abnormal condition models in advance with the measured data. In this detection and diagnosis process, the Dynamic Time Warping (DTW) algorithm, a robust method against time lags between time-series data, is utilized to evaluate the dissimilarity between time-series data. Moreover, fault detection and diagnosis results can be obtained through classification using a hierarchical clustering method based on dissimilarity evaluated by DTW. Based on the trial results of the model-based approach constructed in this research, the possibility of fault detection and diagnosis was demonstrated for virtual EMAs of a liquid rocket engine. In addition, these trial results suggest the possibility of fault diagnostics in several different physical domains and components by measurement data from single sensor. This possibility also suggests that the sensor items for failure detection and diagnosis can be optimized with proposed approach in this study.
    • 11.02 PHM for Autonomous and Control Systems Applications Derek De Vries (Orbital ATK, Inc.)
      • 11.0201 Unmanned Aerial Systems Health Monitoring Architecture Joel Dunham (Georgia Institute of Technology), Eric Johnson (Pennsylvania State University) Presentation: Joel Dunham - Thursday, March 7th, 09:50 PM - Lamar/Gibbon
        As small Unmanned Aerial Systems (UAS) proliferate, encounters between non-participants and UAS become much more frequent. Many of these are due to carelessness or not following rules on the part of the UAS operator. However, even when flying within the rules, encounters —potentially fatal —are possible. To help mitigate the risk of injury by UAS, health monitoring systems are imperative for reducing situations in which loss of control is likely. Current health monitoring tends to use real-time checks for power and navigation issues while a few systems are available for testing changes in vehicle responses to control inputs after flights. To reduce the likelihood of loss of control, we introduce a real-time health monitoring system that analyzes navigation, control, power, sensor, and communications integrity. Through experimental validation, we define metrics which detect degradations in the integrity of each system stated previously. Most failures present symptoms over time which can be detected, preventing the final catastrophic failure from occurring. Information requirements and necessary response times and thresholds are evaluated for each of the monitored subsystems, helping to define the implementation of each integrity check. Integration with a flight controller, particularly on small UAS which do not have the capacity to carry an auxiliary computer, is factored into the architecture, ensuring that health monitoring does not adversely affect flight control. Overall, this architecture provides a template and the considerations necessary for implementing more robust real-time health monitoring systems on the various UAS flight systems in operation.
    • 11.03 PHM System Design Attributes and Architectures Andrew Hess (The Hess PHM Group, Inc.) & Derek De Vries (Orbital ATK, Inc.)
      • 11.0302 Integrated Data Engineering for Automated Labeling (IDEAL) and Future Design of Aircraft Alicia Ruvinsky (US Army ERDC), Warith Abdullah (Engineer Research and Development Center), Lakenya Walker (Engineer Research and Development Center), Maria Seale (USACE Engineer Research and Development Center) Presentation: Alicia Ruvinsky - Wednesday, March 6th, 04:30 PM - Lake/Canyon
        Data analysis and machine learning methods provide information that can be used to (1) reduce costs by enabling a condition-based maintenance program, (2) optimize maintenance scheduling, and (3) influence the designs of future platforms. The work presented here describes the integration of repurposed data and autonomous labeling of such engineered data compilations. This effort is called Integrated Data Engineering for Automated Labeling (IDEAL) and is based on an innovative data engineering approach called Data Programming. IDEAL aims to exploit the wealth of heterogeneous, historical data sets describing different aspects of aircraft performance from sources such as the aircraft on-board data collection system (Health and Usage Monitoring System/Flight Data Recorder) and the off-board maintenance logbook. By generating an integrated data landscape, IDEAL enables the exploration, exploitation, testing, and evaluation of innovative condition indicator (CI) algorithms for better representing the performance state of a platform and its components. In particular, IDEAL supports the Subject Matter Expert-guided characterization of ground-truth labels informing both the integration of disparate data sets and the classification of events within the resulting integrated data set. This mechanism results in massive labeled data sets that allow for the application of machine learning techniques to support the exposure of hidden phenomena embedded within platform performance data.
      • 11.0303 Uncertainty Quantification in Prognostic Health Management Systems Homer Dewey (Northrop Grumman Corporation), Derek De Vries (Orbital ATK, Inc.) Presentation: Homer Dewey - Wednesday, March 6th, 04:55 PM - Lake/Canyon
        Uncertainty plays a role in nearly all aspects of prognostic health management (PHM) systems. Aleatory uncertainty from inherently-variable inputs such as material properties, epistemic uncertainty from a lack of knowledge about the system and its inputs, and ontological uncertainty due to completely unknown factors must all be accounted for in order to provide the most accurate assessment of the health of the monitored system. Northrop Grumman Innovation Systems (NGIS) develops, produces, and provides sustainment of solid rocket motor systems for the aerospace and defense industry and has extensive experience in applying uncertainty quantification (UQ) principles to complicated numerical simulations and analyses. In this presentation, lessons learned by NGIS on UQ simulations and analyses are presented, and their applicability to PHM systems is explored. Methods for measuring and tracking uncertainty through the PHM predictive train are presented, as is a Monte-Carlo-based method for performing prognostic numerical calculations, which accounts for and quantifies epistemic, ontological, and aleatory uncertainty.
      • 11.0304 Structural Diagnostics, Prognostics and Health Management for Future Space Vehicles Andrei Zagrai (New Mexico Institute of Mining and Technology) Presentation: Andrei Zagrai - Wednesday, March 6th, 05:20 PM - Lake/Canyon
        Future space vehicle will incorporate a broad range of technologies for increased safety, situation awareness, and autonomous operation. It is envisioned that diagnostics, prognostics and health management (PHM) will enable monitoring and decision support for a variety of spacecraft systems, components and structures. This contribution highlights PHM elements applicable to space structures. Constitutive elements of PHM are discussed in light of multifaceted management of space structures from fabrication to retirement. In addition to classical PHM elements, aspects unique to space systems are highlighted: pre-launch diagnostics as a pathway to by-pass certain qualification tests, validation of component deployment, catastrophic event monitoring and assessment, and ability to report reentry breakup event. PHM approach to space structures is discussed in light of prior development, implementation and testing of structural health monitoring systems flown in stratospheric and sub-orbital flights as well as prior laboratory work and current development of ISS experiments. Examples of propagating and standing wave damage detection approaches are presented. Physics-based model including sensor, structure and measurement methodology is reported. Impact of space environment factors on sensor and structural response is estimated. It is advocated that the PHM could be a key element of future information-centric space vehicles.
    • 11.05 PHM for Electronics Andrew Hess (The Hess PHM Group, Inc.)
      • 11.0501 Aircraft Actuator Fault Diagnosis Using Deep Learning Based Sparse Representation and TSM Jing Yang (Northwestern Polytechnical University), Yingqing Guo (Northwestern Polytechnical University), Wanli Zhao (Northwestern Polytechnical University) Presentation: Jing Yang - -
        This paper presents a novel data-based fault diagnosis approach of aircraft actuators by using deep learning methods. Electro-mechanical actuator (EMA), which we study on, widely used in a new generation of aircraft serves as the research object. The basic fault diagnosis framework of this work is based on Time Series Modeling (TSM), which builds model for each sensor data, then faults can be detected and isolated by differences between model prediction result and measured result. In this structure, the quantity of sensors is directly related to the fault diagnosis effect, that is, the fault detection capability increases when the number of sensors increases. Simultaneously, the workload of the model training increases without expectation. Therefore, the reduction of sensors is of great significance. The traditional method is to use manual experience to screen, but this method has high requirements on personnel ability and performance is not easy to guarantee. This paper adopts the Sparse Auto-Encoder (SAE) algorithm, which avoids the simple direct screening process and achieves the purpose of reducing the number of sensors by adaptively extracting features. Important features of sensor data, preserved by loss compression using SAE, can be used to build time series models. Relationship of time series adjacent data is adopted to build mathematical models. Compared with traditional machine learning algorithms, recurrent neural network (RNN) algorithm can make good use of the relationship between time series, which has been widely used in speech recognition, text recognition and other fields. However, standard RNN algorithm tends to ignore future information. In this paper, the Bidirectional Long Short-term Memory RNN algorithm (BiLSTM-RNN), considering both past data and future data, is applied to TSM. Through the Comparison of the standard RNN and long short-term memory RNN (LSTM-RNN) algorithms, the biLSTM-RNN algorithm shows better modeling and fault diagnosis performance.
    • 11.06 PHM for Non-Aerospace Applications Joseph Thorp (Aramco) & Andrew Hess (The Hess PHM Group, Inc.)
      • 11.0602 Steady State Frequency Response Utilizing an Enhanced Chirp Test Signal Bryce Hill (Montana Tech), John Morrison (Montana Tech) Presentation: Bryce Hill - Thursday, March 7th, 09:00 PM - Lamar/Gibbon
        Determining the health of a battery in a short period of time can be challenging. In the past, the Impedance Measurement Box (IMB) utilized a Sum Of Sines (SOS) excitation signal of ten to twenty octave step frequencies to measure the spectrum impedance of a battery. The individual sine wave time domain signals were added on top of each other. Though this was useful and effective, the combined values of the sinusoidal signals resulted in a magnitude limit in resolution due to a "rogue wave" effect when multiple sine waves peaked simultaneously, thus creating a larger maximum excitation value for smaller individual amplitudes for each frequency. If time needed to test the battery can be sacrificed, then the solution is to perform the same impedance test with a frequency chirp as the excitation signal. In this work we compare the previous method of battery impedance measurement using SOS to the proposed method of a chirp signal. The comparison was first performed using a simulation of the test setup, and then using the IMB to test a cell consecutively with the SOS and the new chirp analysis. With minor modifications to the chirp approach, the chirp analysis was found to be as effective as the SOS approach in determining the cell's impedance spectrum. Though the time needed to test the cell was increased, the factor is only approximately 65% longer than with the SOS approach. The added magnitude resolution of the chirp signal enhances the signal-to-noise ratio by a factor of approximately 10 and the rogue wave effect is reduced by approximately a factor of two.
      • 11.0603 State-wise LSTM-GRU Method for Ball Screw Health Prediction Kaizheng Wang (Shanghai Jiao Tong University), Yixiang Huang (Shanghai Jiao Tong University), Liang Gong (), Chang Cai (), Yifan Zhang () Presentation: Yixiang Huang - Thursday, March 7th, 09:25 PM - Lamar/Gibbon
        Ball screws play important roles in wide applications related to aircraft equipment and its manufacturing process. For these highly complex systems, their demands for reliability is high and strict. Thus, the precise evaluation and prediction of the health status of the ball screws is necessary. The popular approaches of degradation prediction for the ball screws are based on the presumption that the degradation trend of the ball screw is monotonically changing. However, the degradation trend often varies due to multiple independent or coupled factors. For example, due to different operation conditions, the degradation of the ball screw performance may go through a “decrease-increase-decrease” trend. In such cases, a single degradation model cannot accurately describe how the degradation develops. So it is still an open question with challenges from many aspects. In this paper, we try to predict the health of the ball screw by dividing the degradation process into several different trends with the assumption that the trend changes with the status of the ball screw. To achieve this, a new prediction model is proposed based on a state-wise deep learning method of the long short term memory network and gated recurrent unit (LSTM-GRU). The main steps of the proposed method include: 1) to extract the features that may be sensitive to the status of the ball screw; 2) to fuse the features and reduce the dimension by using the kernel principal component analysis (KPCA); 3) to establish a distance space that can measure the deviation from the healthy status of the ball screws by using Mahalanobis metric. 4) to evaluate the health status of the ball screw by using the method of the density-based spatial clustering of applications with noise (DBSCAN); 5) to predict the performance state of the ball screw by applying the method of LSTM-GRU. The proposed method of the state-wise LSTM-GRU is validated on a life-cycle experiment of the ball screw, and then compared with the standard long short term memory network (LSTM) and the method of gated recurrent unit(GRU). Results show that the proposed model of state-wise LSTM-GRU can predict the performance state of the ball screw more accurately and more robust, which indicates it is a promising method for the performance prediction of the ball screws.
    • 11.07 PHM for Human Health and Performance Alexandre Popov (AIAA SETC) & Wolfgang Fink (University of Arizona)
      • 11.07 11.07 Keynote: Engineering Problems in Clinical and Space Medicine Daniel Buckland Presentation: Daniel Buckland - - Lake/Canyon
      • 11.0702 Design Considerations for UAV-Delivered Opioid Overdose Interventions Daniel Buckland (), Mary Cummings () Presentation: Daniel Buckland - Wednesday, March 6th, 09:50 PM - Lake/Canyon
        With recent regulatory changes that allow for commercial unmanned aerial vehicle (UAV) operations, there has been increasing interest in using UAVs, aka drones, for delivery of medical care, especially in rural areas. Previous work has focused on Automated External Defibrillators (AEDs) for people in possible cardiac arrest, but there are potentially many other emergency medical interventions that could be made more readily available through drones. One such use includes treatment for opioid overdoses, which could be significant given the current US opioid crisis. While drone delivery of blood has been established in Africa between medical professionals, there are no established applications of drones delivering emergency medical interventions for use by bystanders due to technical issues in the safe operation of drones in the air and in accessing and using the medical devices on the ground by laypersons. This presentation examines how such a drone system should be designed in order to promote safe and effective operations for all stakeholders. This complex system design problem should be addressed at both local and global levels. At the local level, new theories and applications of human-technology interaction should be developed considering the need to promote safe and efficient human interaction between bystanders and drones delivering emergency medical interventions. Resulting models will need to consider how affordances can be designed into the technology given the use by untrained bystanders. Given that these emergency drones will need to be remotely supervised, the global aspect of this research should focus on the development of a drone supervision/dispatch capability, which will include interacting with the layperson who initiated the emergency call and determining how to integrate new network optimizations models so that dispatchers can understand when and where to dispatch drones and/or ambulances.
      • 11.0704 “PHM for Astronauts” Project to Run on the International Space Station: The Status and Plan Forward Alexandre Popov (AIAA SETC), Wolfgang Fink (University of Arizona), Andrew Hess (The Hess PHM Group, Inc.) Presentation: Alexandre Popov - Wednesday, March 6th, 09:25 PM - Lake/Canyon
        This paper reports on the “PHM for Astronauts” project status. The project is to validate the “PHM for Human Health and Performance (HH&P)” concept that was originally introduced as a predictive diagnostics concept for space medicine in the paper “System Health Management and Space Medicine Predictive Diagnostics. Common Concepts and Approaches.” in 2012 and then was elaborated and further evolved by the authors over the last seven years. Discussing the project on validation of the advanced concept and corresponding technology candidates with predictive screening capability on the International Space Station (ISS), this paper focuses on a plan to move forward with the project, i.e., the plan to complete the project inception phase and to move into the implementation phase of the project in terms of the current ISS status, evolving ISS program, and latest international developments. This paper also discusses the forward planning exercise in terms of recommendations by experienced astronauts and healthcare professionals on crewed space programs as well as the National Space Exploration Campaign Report recently released by NASA in order to develop a Human Exploration Roadmap that will include a critical decision plan to expand human presence beyond low-Earth orbit (LEO). The novelty of the to-be-validated concept on crew health maintenance is to employ PHM-based solutions with predictive screening capability, providing early and actionable real-time warnings of impending health issues that otherwise would have gone undetected unless a symptom is manifested or a sign is detected at a relatively late stage.
    • 11.09 PHM FOR PRECISION AGRICULTURE AND NATURAL RESOURCE PROSPECTING Stan Martin (Bayer) & Joseph Thorp (Aramco) & Thomas George (SaraniaSat Inc.)
      • 11.0901 Soil Organic Matter Mapping Using Hyperspectral Imagery and Elevation Data Laurynas Gedminas (LifeScale Analytics) Presentation: Laurynas Gedminas - Thursday, March 7th, 04:30 PM - Lamar/Gibbon
        Knowledge of the spatial distribution of soil organic matter (OM) is highly important in many of today’s applications of digital agriculture. Spatial OM awareness provides important insights to agronomists and allows the application of farm management practices in the right locations. Soil organic matter, which accumulates as a result of plant and animal decomposition, affects soil reflectance properties. The concentration of soil organic matter can be detected using aerial imagery, where darker images are correlated with higher OM concentration. In this paper we evaluate different approaches to OM analysis using hyperspectral imagery. By utilizing bare earth fields we can analyze a single image for the field without the need to acquire multiple images during the growing season or to time image acquisition before plant senescence and vegetation indice saturation. Here we report on a study in which bare earth spectral images, together with soil samples were collected in various counties in the Midwest. Two meter LIDAR digital elevation models were obtained from public sources. Soil reflectance, elevation, and topographic attributes and indices were used to describe the correlation between soil organic matter and various bands. Automated machine learning methods were used to analyze the relationship between soil spectral reflectance and soil organic matter.
      • 11.0902 Comparison of Mid Wave Infrared (MWIR) and Long Wave Infrared (LWIR) Imagery for Precision Ag. Thomas George (SaraniaSat Inc.) Presentation: Wolfgang Fink - Thursday, March 7th, 04:55 PM - Lamar/Gibbon
        long standing debate has existed on the utility of Mid Wave Infrared (MWIR) vs Long Wave Infrared (LWIR) remote-sensing imagery for Precision Agriculture applications. We have conducted a combined qualitative and quantitative, multi-field, aircraft remote-sensing study to show that LWIR measurements often result in more actionable for day-to-day farm management applications. LWIR imagery when processed with SaraniaSat’s nonlinear, weak-signal detection algorithms is an effective predictor of crops stress and ultimate harvest yield. It is also shown that both processed LWIR and MWIR imagery contain actionable, crop-stress information that is absent in the conventional Normalized Difference Vegetation Index (NDVI) that is currently, widely used for Precision Agriculture. Finally, at a simulated 10m ground resolution (satellite remote sensing) it is shown, once again, that LWIR is superior and more actionable.
    • 11.10 Panel: PHM from a Practitioner’s Perspective – a Potpourri of Capabilities, Experiences, Issues, and Lessons Learned Michael Houck (NAVAIR 4.4.2, Propulsion & Power) & Andrew Hess (The Hess PHM Group, Inc.)
      • 11.10 11.10 Panel: PHM from a Practitioner’s Perspective – a Potpourri of Capabilities, Experiences, Issues, and Lessons Learned Andrew Hess, Michael Houck Presentation: Andrew Hess, Michael Houck - - Lake/Canyon
        Practitioners in the PHM field are solicited to share their experiences and observations as part of a distinguished panel of experts. A short presentation will be required of all participants that describes their focus topic within the PHM and CBM+ domains. This session will cover a broad range of research, lessons-learned experiences and application topics covering the challenges and innovative engineering and/or business approaches associated with the development and implementation of PHM capabilities and CBM+ architectures. The session will feature presentations by senior leaders in the field and a panel discussion. Panel members from PHM communities, academia, government, and industry, will focus on strategies that have or will resolve historical issues, and challenges, and provide insight. Interested parties should contact the session organizers.
  • 12 Ground and Space Operations David La Vallee (Johns Hopkins University APL) & Carlos Gomez Rosa (NASA - Goddard Space Flight Center)
    • 12.01 Spacecraft Development and Flight Operations: Challenges, Successes, Failures and Lessons Learned Mona Witkowski (Jet Propulsion Laboratory) & Allan Cheuvront (General Dynamics C4 Systems)
      • 12.0102 Refactoring the Curiosity Rover's Sample Handling Architecture on Mars Vandi Verma (NASA JPL-Caltech), Stephen Kuhn () Presentation: Vandi Verma - -
        The Curiosity Mars rover sample handling hardware and software were architected assuming that end-to-end sampling operations would occur in a single rover position, from acquisition of a powdered sample with a scoop or drill, through to the cleaning out of all sample residue in the sample chain. However, after analysis of the first drilled samples in Yellowknife Bay, the science team wanted to iterate with additional experiments on Mars and in laboratories on Earth to better understand their results and increase the value of science returned. With the architecture as conceived, the time needed to do so was in direct competition with the exploration of other targets and satisfaction of success criteria during the prime mission. The science team desired the capability to “cache” the sample for future use while continuing progress towards mission objectives by driving away and maintaining use of the robotic arm for contact science. Allowing sample to move about freely in this state risked hardware damage, ending the ability to deliver sample using the nominal path. In this paper we present the approaches that were developed to repurpose some of the sampling hardware into a series of caches and catchments that reduced this hardware risk to a level acceptable during the prime mission. This approach presented new challenges for rover planners, who had to learn to command the robotic arm using new routines that were too complicated to manage without assistance. The rover planner Software Simulation (“SSim”) was updated for autonomously tracking the turret gravity vector and sample state, generating an execution error or breakpoint as constraints were violated. Sample from the Cumberland drill target was cached for over 9 months, facilitating a number of scientific discoveries. As data accumulated and the mission transitioned into extended operations, the cached sample capability evolved to significantly simplify operations and reduce overhead.
      • 12.0103 Landsat 8: TIRS SSM Encoder Current Anomaly Resolution Martin England (United States Geologic Survey (USGS), Earth Resources Observation and Science (EROS) Center ) Presentation: Martin England - Sunday, March 3th, 04:30 PM - Elbow 1
        Landsat 8 (L8) is the latest in the ongoing series of Earth Observing Satellites jointly developed by the United States Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA) and flown operationally by the USGS Earth Resources Observation and Science Center (USGS/EROS) from a Mission Operations Center (MOC) at NASA’s Goddard Space Flight Center (NASA/GSFC). Landsat 8 was launched (as Landsat Data Continuity Mission (LDCM) on February 11, 2013 from Vandenberg Air Force Base in California into a Low-earth orbit (LEO) (Sun-synchronous orbit at an altitude of 705 km (438 mi, Inclined 98.2° (slightly retrograde), and Equatorial crossing time (descending node): 10:00a.m. +/- 15 minutes). L8 continues the 45 year history of Earth Resources observations (since July 23, 1972) starting with the Earth Resources Technology Satellite-1 (ERTS-1), later named Landsat 1. The Landsat program represents the world’s longest continuously acquired collection of space-based moderate-resolution land remote sensing data. This paper will document the Thermal Infrared Sensor (TIRS) anomaly, and the ultimate return to “new nominal” operations using an Alternate ConOps (ACO). The paper will include samples of the anomalous data, details of the ARB investigations, the ambient ground tests, the ACO paradigm and differences between the nominal and ACO.
      • 12.0105 CloudSat’s A-Train Exit and the Formation of the C-Train: An Orbital Dynamics Perspective Barbara Braun () Presentation: Barbara Braun - Sunday, March 3th, 04:55 PM - Elbow 1
        In February 2018, a series of reaction wheel anomalies forced CloudSat to exit the NASA's A-Train, but in October 2018, CloudSat established a new formation at a lower altitude with its long-time formation-flying partner, the French CALIPSO satellite. This presentation discusses the establishment of the “C-Train” and the challenging series of orbital maneuvers required to get there. Despite the challenges, CloudSat was able to exit the A-Train safely, re-shape its orbit at a new lower altitude, and work with the CALIPSO team to establish a new formation for coincident science measurements.
    • 12.02 Flight/Ground Systems, Mission Planning and Operations Judith Furman (Southwest Research Institute) & Carlos Gomez Rosa (NASA - Goddard Space Flight Center)
      • 12.0201 Automated Spacecraft Operations during Soil Moisture Active Passive Prime Mission Masashi Mizukami (Jet Propulsion Laboratory) Presentation: Masashi Mizukami - Monday, March 4th, 04:55 PM - Cheyenne
        Autonomy and automation of spacecraft operations have been long sought goals to reduce costs and risks. Many different approaches depending on the particular mission's needs and characteristics have been tried and taken. Soil Moisture Active Passive (SMAP) is a science spacecraft mission measuring soil moisture, freeze/thaw and other parameters on a global scale, to support weather forecasting, disaster response and climate research. The spacecraft is fairly conventional and is in a sun synchronous near-polar low Earth orbit. The sole instrument is an L-band passive radiometer; the active radar component is currently inoperative. Automation is a characteristic feature of SMAP flight operations. The project practices "lights-out" operations, where the control room is not staffed, except for occasional real time or contingency activities. Operators nominally work only during regular business hours. Activities are planned and set up on a weekly cadence, and automated processes conduct data processing and commanding. Continuous downlink monitoring is enabled by a sophisticated notification architecture, along with weekly telemetry review by experts. A suite of tools and processes are used to implement the automation. Other tools and resources, while not strictly speaking automation, improve efficiency and reliability, which fundamentally achieve the same benefits as automation. As might be anticipated, there are challenges with a complex ground system that link together many disparate elements. On balance, spacecraft operational costs are estimated to be much lower than if the mission was flown in a conventional manner. In summary, the overwhelming majority of commanding during science phase are performed autonomously, without direct human intervention. A very low command error rate was achieved. It is proposed this concept of operations may serve as a useful model for future missions with similar characteristics.
      • 12.0204 SSim: NASA Mars Rover Robotics Flight Software Simulation Vandi Verma (NASA JPL-Caltech) Electronic Presentation: - Electronic Presentation Hall
        Abstract—Each new Mars rover has pursued increasingly richer science while tolerating a wider variety of environmental conditions and hardware degradation over longer mission operation duration. Sojourner operated for 83 sols (Martian days), Spirit for 2208 sols, and Opportunity is at 5111 sols, and Curiosity operation is ongoing at 2208 sols. To handle this increase in capability, the complexity of onboard flight software has increased. MSL (also known as Curiosity), uses more flight software lines of code than all previous missions to Mars combined, including both successes and failures. MSL has more than 4,200 commands with as many as dozens of arguments, 54,000 parameters, and tens of thousands of additional state variables. A single high-level command may perform hours of configurable robotic arm and sampling behavior. Incorrect usage can result in the loss of an activity or the loss of the mission. Surface Simulation (“SSim”) was developed to address the challenge of making full and effective use of many capabilities of MSL, while managing complexity and risk. SSim is software that performs rapid context sensitive simulation of flight software. NASA Mars missions are comprised of three phases: several months of Cruise, a brief but exciting Entry Descent and Landing (EDL), and a Surface mission that typically lasts as long as the hardware survives. SSim is meant for use during the surface phase when the mission fulfills its primary objectives. The focus of SSim on MSL was the robotic flight software, including rover mobility and navigation, robotic arm manipulation, and sample acquisition, processing, and delivery. It can execute behaviors in simulation a thousand times faster than they execute in real time on the flight compute element. SSim is used by rover drivers to develop and validate command sequences throughout the planning cycle. SSim has been used to plan all of the Curiosity robotic operations since landing and is expected to continue to be used for the remaining life of the rover. Due to the impact of SSim on MSL, the Mars 2020 mission plans to increase the scope of SSim during flight operations, simulating not only rover planner operations, but all surface operations, including the instrument, power, thermal and telecommunication behavior. SSim is part of the Rover Sequencing and Visualization (RSVP) suite of Rover Planning tools. In the paper we provide an overview of SSim architecture, design, implementation, and usage on MSL, as well as an overview of plans for Mars 2020.
      • 12.0205 The Role of the Instrument Suite Systems Engineer in MMS Fleet Operations Paul Wood (Southwest Research Institute), Martin Wasiewicz (Southwest Research Institute) Presentation: Paul Wood - Monday, March 4th, 05:20 PM - Cheyenne
        The operations concept for the Magnetospheric Multiscale (MMS) mission includes the notion of a systems engineer for the Instrument Suite (IS), that is, the collection of instruments in aggregate on each spacecraft and across the fleet. This paper discusses the role of the instrument suite systems engineer (ISSE) over the course of the mission including the six-month commissioning period, the two-year primary mission, and the ongoing extended mission. Some of the activities the ISSE supports include deployments, initial high voltage operations, maneuvers, operation of the central instrument data processor, and interactions between instruments. The ISSE fills the gap between the Payload Operations Center (POC) and the instrument teams by providing in depth knowledge of the IS and instrument designs and the IS concept of operations put into force by the POC.
      • 12.0208 Title: When You Have More Satellites than People: The Evolution of CYGNSS Flight Operations Richard Medina (Southwest Research Institute), Jillian Redfern (Southwest Research Institute), William Wells () Presentation: Richard Medina - Monday, March 4th, 09:00 PM - Cheyenne
        This presentation will cover the challenges the CYGNSS operations team faced after launch and during normal operations Details will be provided on how the CYGNSS team met the demands of operating a constellation of eight satellites with a dwindling support staff and under the cost constraints of a NASA Class D mission. This presentation will detail the tools and methods we used to meet the demands of collecting high fidelity science during the 2017 and 2018 Atlantic hurricane seasons, as well as improving the efficiency of our operations so we can do "more with less".
      • 12.0211 Planetary Rover Simulation for Lunar Exploration Missions Mark Allan (KBRwyle), Uland Wong (), Terry Welsh (NASA Ames Research Center), P. Michael Furlong (), Scott Mc Michael (NASA - Ames Research Center), Arno Rogg (NASA - Ames Research Center), Brian Gerkey (), Ian Chen (Open Source Robotics Foundation), Steven Peters (Open Robotics), Morgan Quigley (Open Robotics), Matthew Deans (), Terrence Fong (NASA Ames Research Center) Presentation: Mark Allan - -
        When planning planetary rover missions it is useful to develop intuition and skills driving in, quite literally, alien environments before incurring the cost of reaching said locales. Simulators make it possible to operate in environments that have the physical characteristics of target locations without the expense and overhead of extensive physical tests. To that end, NASA Ames and Open Robotics collaborated on a Lunar rover driving simulator based on the open source Gazebo simulation platform and leveraging ROS (Robotic Operating System) components. The simulator was integrated with research and mission software for rover driving, system monitoring, and science instrument simulation to constitute an end-to-end Lunar mission simulation capability. This presentation introduces the Resource Prospector (RP) Driving ConOps Simulator, an end-to-end simulation used to develop and refine the RP concept of operations.
    • 12.04 Human Space Flight Development, Operations and Processing Matthew Miller (Jacobs/NASA JSC) & Michael Lee (NASA - Kennedy Space Center)
      • 12.0401 Orion Heat Shield Manufacturing Producibility Improvements for the EM-1 Flight Test Program Richard Harris (ASRC Federal) Presentation: William Koenig - Sunday, March 3th, 05:20 PM - Elbow 1
        This paper describes how the Orion program is incorporating improvements in the heat shield design and manufacturing processes reducing programmatic risk and ensuring crew safety in support of NASA’s Exploration Missions. The Orion program successfully completed the EFT-1 flight test in 2014 and is currently developing the EM-1 spacecraft to meet the test objectives of an orbital mission to the moon and return to earth in 2019. Lessons learned from the EFT-1 manufacturing and flight test experience are being incorporated into a wide variety of vehicle systems and manufacturing processes to reduce risk to the Orion missions and flight crew. A critical contributor to crew safety is the heat shield that protects the crew capsule during re-entry through the earth’s atmosphere for return from deep space. The first flight test vehicle, EFT-1, was manufactured and tested in the Neil Armstrong Operations and Checkout (O&C) facility at KSC to demonstrate early risk reduction including the functionality of the Thermal Protection Systems (TPS) for capsule safe return to earth. The approach for the EFT-1 heat shield utilized a low risk approach using Apollo heritage design and manufacturing processes using an Avcoat TPS ablator with a honeycomb substrate to provide a one piece heat shield to meet the mission re-entry heating environments. The manufacturing processes used honeycomb cell injection guns which were redeveloped from the Apollo Lunar Program processes to build the EFT-1 heat shield. The completed heat shield was transported across the country by aircraft to the O&C at KSC for installation onto the capsule. The EFT-1 heat shield successfully performed its mission and experienced ~80% of the re-entry velocity (50% heating rate) for a lunar return for an Exploration Mission. The second flight test vehicle is the EM-1 mission which will have additional flight systems installed to fly to the moon and return. Heat shield design and producibility improvements have been incorporated in the EM-1 vehicle to meet deep space mission and programmatic requirements. The design continues to use the Avcoat material, but in a “block” configuration to enable improvements in the application processes as well as additional improvements in the carrier structure design and manufacturing operations. Incorporating flight test results and producibility improvements from EFT-1 for the heat shield system design and processes have improved the thermal protection capability, reduced programmatic risks, and program cost for the EM-1 flight test program.
    • 12.05 Payload and Instrument Operations and Planning Radu Popescu (Radiant Solutions) & David La Vallee (Johns Hopkins University APL)
      • 12.0501 Updates in Commissioning Timeline for NASA-ISRO Synthetic Aperture Radar (NISAR) Priyanka Sharma (Jet Propulsion Laboratory) Presentation: Priyanka Sharma - Sunday, March 3th, 09:00 PM - Elbow 1
        The NASA-ISRO Synthetic Aperture Radar, or NISAR, Mission is a multi-disciplinary Radar mission to make integrated measurements to understand the causes and consequences of land surface changes on Earth. NISAR will provide a means of disentangling and clarifying spatially and temporally complex phenomena on Earth, ranging from ecosystem disturbances, to ice sheet collapse and natural hazards including earthquakes, tsunamis, volcanoes and landslides. NISAR is a joint partnership between the National Aeronautics and Space Administration (NASA) and the Indian Space Research Organization (ISRO). The target launch date for the mission is jANUARY 2022. The NASA L-SAR and ISRO S-SAR Radar instruments will provide global and complementary datasets with a 12-day repeat cycle, for addressing compelling scientific questions in the fields of Solid Earth deformation, Ecosystems and Cryospheric sciences. The prime Science Phase for NISAR will be three years in duration. Prior to beginning the Science Phase, all the observatory elements, including the spacecraft bus, the Radar payload instruments, the JPL Engineering Payload and the Reflector Boom Assembly will be checked out during the In-Orbit Checkout or Commissioning Phase, which will last for 90 days after launch. During the Commissioning Phase, there will be a step-by-step buildup in capability to full observatory operations, starting with ‘Initial Checkout’, ‘Reflector Boom Assembly Deployment,’ ‘Spacecraft Checkout’ and finally ‘Instrument Checkout’. Updates made to the NISAR Commissioning timeline in the Project’s Phase C have focused on further refinement of the Instrument Checkout phase in particular. During this phase, both the L-SAR and S-SAR instruments will be powered on, their performance will be characterized and calibrated, initial calibrations will be performed to develop calibration strategies and demonstrate the instruments are ‘calibratable’ in the following 5 months of Science Calibration/Validation phase during nominal science operations. Initial power-on and calibration activities for L-SAR and S-SAR have been interleaved in the timeline. In addition, investigations of the ground processing activities (for example, data processing, data analysis, uplinks, downlinks) to be performed during successive calibrations are currently underway. Allocating sufficient time for these ground-in-the-loop activities is critical to the development of a realistic timeline with a healthy margin.
      • 12.0502 Two Years at Jupiter: A Review of the JUNO JADE Operations and Systems Engineering Toolset Patrick Phelan (Southwest Research Institute) Presentation: Patrick Phelan - Sunday, March 3th, 09:25 PM - Elbow 1
        NASA’s Juno mission to Jupiter launched in August 2011 with a five year cruise phase. Upon arrival in July 2016, Juno entered into a 53-day orbit around the planet. Of the ten instruments on board the spacecraft, the Jovian Auroral Distributions Experiment (JADE) instrument is responsible for the measurements of electrons and ions that help us understand the Jovian magnetosphere. To support this instrument, a team at Southwest Research Institute (SwRI) and other organizations composed of scientists, operations staff, and engineers has developed a set of tools to provide commanding, as well as assess its science data and engineering state of health. This paper focuses on a description of the tools used for JADE instrument commanding and assessing the instrument’s state of health, how they are implemented, and the lessons learned along the way. The paper will close with a forward look at the exciting orbits to come and how these tools will be evolved to meet the needs of the team.
    • 12.06 Information Technology and Cyber Security Roles in Operations Jon Handiboe (JHU/APL) & Gabrielle Griffith (Johns Hopkins University APL)