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  • 1
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    Compute Element and Interface Box for the Hazard Detection System (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The Autonomous Landing and Hazard Avoidance Technology (ALHAT) program is building a sensor that enables a spacecraft to evaluate autonomously a potential landing area to generate a list of hazardous and safe landing sites. It will also provide navigation inputs relative to those safe sites. The Hazard Detection System Compute Element (HDS-CE) box combines a field-programmable gate array (FPGA) board for sensor integration and timing, with a multicore computer board for processing. The FPGA does system-level timing and data aggregation, and acts as a go-between, removing the real-time requirements from the processor and labeling events with a high resolution time. The processor manages the behavior of the system, controls the instruments connected to the HDS-CE, and services the "heavy lifting" computational requirements for analyzing the potential landing spots.
    Keywords: Man/System Technology and Life Support
    Type: NPO-48786 , NASA Tech Briefs, April 2013; 12-13
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Attitude Determination and Control Subsystem (ADCS) Preparations for the EPOXI Flyby of Comet Haley 2 (2011)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: On November 4, 2010 the already "in-flight" Deep Impact spacecraft flew within 700km of comet 103P/Hartley 2 as part of its extended mission EPOXI, the 5th time to date any spacecraft visited a comet. In 2005, the spacecraft had previously imaged a probe impact comet Tempel 1. The EPOXI flyby marked the first time in history that two comets were explored with the same instruments on a re-used spacecraft-with hardware and software originally designed and optimized for a different mission. This made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby. As part of the spacecraft team preparations, the ADCS team had to perform thorough sequence reviews, key spacecraft activities and onboard calibrations. These activities included: review of background sequences for the initial conditions vector, sun sensor coefficients, and reaction wheel assembly (RWA) de-saturations; design and execution of 10 trajectory correction maneuvers; science calibration of the two telescope instruments; a flight demonstration of the fastest turns conducted by the spacecraft between Earth and comet point; and assessment of RWA health (given RWA problems on other spacecraft).
    Keywords: Spacecraft Design, Testing and Performance
    Type: AIAA Guidance, Navigation, and Control Conference; Aug 08, 2011; Portland, OR; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Flight Testing a Real-Time Hazard Detection System for Safe Lunar Landing on the Rocket-Powered Morpheus Vehicle (2015)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Hazard Detection System (HDS) is a component of the ALHAT (Autonomous Landing and Hazard Avoidance Technology) sensor suite, which together provide a lander Guidance, Navigation and Control (GN&C) system with the relevant measurements necessary to enable safe precision landing under any lighting conditions. The HDS consists of a stand-alone compute element (CE), an Inertial Measurement Unit (IMU), and a gimbaled flash LIDAR sensor that are used, in real-time, to generate a Digital Elevation Map (DEM) of the landing terrain, detect candidate safe landing sites for the vehicle through Hazard Detection (HD), and generate hazard-relative navigation (HRN) measurements used for safe precision landing. Following an extensive ground and helicopter test campaign, ALHAT was integrated onto the Morpheus rocket-powered terrestrial test vehicle in March 2014. Morpheus and ALHAT then performed five successful free flights at the simulated lunar hazard field constructed at the Shuttle Landing Facility (SLF) at Kennedy Space Center, for the first time testing the full system on a lunar-like approach geometry in a relevant dynamic environment. During these flights, the HDS successfully generated DEMs, correctly identified safe landing sites and provided HRN measurements to the vehicle, marking the first autonomous landing of a NASA rocket-powered vehicle in hazardous terrain. This paper provides a brief overview of the HDS architecture and describes its in-flight performance.
    Keywords: Spacecraft Design, Testing and Performance
    Type: AIAA Scitech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimee, FL; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Simulations of the Hazard Detection System for Approach Trajectories of the Morpheus Lunar Lander (2015)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Hazard Detection System is part of a suite of sensors and algorithms designed to autonomously land a vehicle on unknown terrain while avoiding any hazards. This paper describes the simulations built to predict the performance of the Hazard Detection System to support flight testing onboard the Morpheus Lander testbed at the Kennedy Space Center. The paper describes a hardware-in-the-loop simulation that was used to predict system performance under nominal operating conditions, and also a Monte Carlo simulation to predict command timing performance bounds under a wide range of varying conditions.
    Keywords: Spacecraft Design, Testing and Performance
    Type: AIAA Scitech 2015; Jan 01, 2015 - Jan 05, 2015; Kissimee, FL; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Attitude Determination and Control Subsystem (ADCS) Preparations for the EPOXI Flyby of Comet Hartley 2 (2011)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: On November 4, 2010 the former "Deep Impact" spacecraft, renamed "EPOXI" for its extended mission, flew within 700km of comet 103P/Hartley 2. In July 2005, the spacecraft had previously imaged a probe impact of comet Tempel 1. The EPOXI flyby was the fifth close encounter of a spacecraft with a comet nucleus and marked the first time in history that two comet nuclei were imaged at close range with the same suite of onboard science instruments. This challenging objective made the function of the attitude determination and control subsystem (ADCS) critical to the successful execution of the EPOXI flyby.As part of the spacecraft flyby preparations, the ADCS operations team had to perform meticulous sequence reviews, implement complex spacecraft engineering and science activities and perform numerous onboard calibrations. ADCS contributions included design and execution of 10 trajectory correction maneuvers, the science calibration of the two telescopic instruments, an in-flight demonstration of high-rate turns between Earth and comet point, and an ongoing assessment of reaction wheel health. The ADCS team was also responsible for command sequences that included updates to the onboard ephemeris and sun sensor coefficients and implementation of reaction wheel assembly (RWA) de-saturations.
    Keywords: Aircraft Stability and Control
    Type: AIAA Guidance, Navigation, and Control Conference; Aug 08, 2011 - Aug 11, 2011; Portland, OR; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Evaluation of the Simple Safe Site Selection (S4) Hazard Detection Algorithm Using Helicopter Field Test Data (2017)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Small scale terrain hazards, such as rocks, slopes, and craters, can pose significant risk to landing spacecraft and rover or payload deployment. Onboard Hazard Detection and Avoidance (HDA) systems scan and analyze the landing area for these hazards in real time during descent, and divert the spacecraft to the safest touchdown site. The computationally efficient Simple Safe Site Selection (S4) algorithm combined with a flash LIDAR is an HDA system geared towards small robotic spacecraft. Rather than creating and analyzing a digital elevation map (DEM) from potentially many overlapping range images, S4 operates directly on a single flash LIDAR image. Extending prior work that has analyzed S4 performance for Mars landing using extensive simulations, this paper evaluates S4 performance using actual flash LIDAR images of an artificial hazard field acquired during a 2014 helicopter field test in Death Valley, CA. In particular, we describe LIDAR characterization and calibration, creation of ground truth elevation and safety maps, creation of ground truth sensor poses, actual S4 algorithm processing, and performance analysis. The results show that the safety cost images produced by S4 are remarkably close to the ground truth safety map (computed offline by an HDA algorithm developed under the Autonomous Landing and Hazard Avoidance (ALHAT) project) at significantly reduced computational cost, confirming S4 as a viable candidate algorithm for onboard spacecraft HDA.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JPL-CL-16-5852 , AIAA SciTech 2017; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
    Format: text
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    NASA TECHNICAL REPORTS
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