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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
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NASA NTRS2016

Validation of GNSS Multipath Model for Space Proximity Operations Using the Hubble Servicing Mission 4 Experiment

In the rendezvous and docking of spacecraft, GNSS signals can reflect off the target vehicle and cause prohibitively large errors in the chaser vehicle receiver at ranges below 200 meters. It has been proposed that the additional ray paths, or multipath, be used as a source of information about the state of the target relative to the receiver. With Hubble Servicing Mission 4 as a case study, electromagnetic ray tracing has been used to construct a model of reflected signals from known geometry. Oscillations in the prompt correlator power due to multipath, known as multipath fading, are studied as a means of model validation. Agreement between the measured and simulated multipath fading serves to confirm the presence of signals reflected off the target spacecraft that might be used for relative navigation.

Ashman, Ben↗
NASA NTRS2015

Multiplying Mars Lander Opportunities with Marsdrop Microlanders

From canyons to glaciers, from geology to astrobiology, the amount of exciting surface science awaiting us at Mars greatly outstrips available mission opportunities. Based on the thrice -flown Aerospace Corporation Earth Reentry Breakup Recorder (REBR), we present a method for accurate landing of small instrument payloads on Mars, utilizing excess cruise -stage mass on larger missions. One to a few such microlanders might add 1-5% to the cost of a primary mission with inconsequential risk. Using the REBR and JPL Deep Space 2 starting points for a passively stable entry vehicle provides a low mass and low ballistic coefficient, enabling subsonic d employment of a steerable parawing glider, capable of 10+ km of guided flight at a 3:1 glide ratio. Originally developed for the Gemini human space program, the parawing is attractive for a volume -limited microprobe, minimizing descent velocity, and providing sufficient remaining volume for a useful scientific payload. The ability to steer the parawing during descent opens unique opportunities, including terrain- relative navigation for landing within tens of meters of one of several specified targets within a given uncertainty ellipse. In addition to scientific value, some Mars human exploration Strategic Knowledge Gaps could be addressed with deployment of focused instruments at multiple locations.

Staehle, Robert L.↗
NASA NTRS2010

NASA Accelerates SpaceCube Technology into Orbit

On May 11, 2009, STS-125 Space Shuttle Atlantis blasted off from Kennedy Space Center on a historic mission to service the Hubble Space Telescope (HST). In addition to sending up the hardware and tools required to repair the observatory, the servicing team at NASA's Goddard Space Flight Center also sent along a complex experimental payload called Relative Navigation Sensors (RNS). The main objective of the RNS payload was to provide real-time image tracking of HST during rendezvous and docking operations. RNS was a complete success, and was brought to life by four Xilinx FPGAs (Field Programmable Gate Arrays) tightly packed into one integrated computer called SpaceCube. SpaceCube is a compact, reconfigurable, multiprocessor computing platform for space applications demanding extreme processing capabilities based on Xilinx Virtex 4 FX60 FPGAs. In a matter of months, the concept quickly went from the white board to a fully funded flight project. The 4-inch by 4-inch SpaceCube processor card was prototyped by a group of Goddard engineers using internal research funding. Once engineers were able to demonstrate the processing power of SpaceCube to NASA, HST management stood behind the product and invested in a flight qualified version, inserting it into the heart of the RNS system. With the determination of putting Xilinx into space, the team strengthened to a small army and delivered a fully functional, space qualified system to the mission.

Petrick, David↗
NASA NTRS2017

Omnidirectional Inter-Satellite Optical Communicator (ISOC)

The objective of the Omnidirectional Inter-Satellite Optical Communicator (ISOC) project is to design a compact, lightweight,and energy efficient communicator module for use between satellites in space. This module will achieve continuous optical communication, with simultaneous data transmission and reception, at up to1 gigabit per second (Gbits) data rates for small spacecraft separated by up to 200 kilometers (kms). To achieve this goal,a data communicator with full spherical coverage field of view (FOV) needs to be designed. The proposed ISOC is a dodecahedron geometric array of chipscale, microelectromechanical systems (MEMS) based gimbal-less scanning mirrors that provide adjustable beam pointing and spherical FOV coverage for uninterrupted data transmission between several small spacecraft at arbitrary relative positions. This design eliminates known pointing issues and hence allows accurate direction of arrival calculations.Moreover, the proposed approach will enable data relaying between multiple satellites, and enable relative navigation control.

Inter-small satellite communication↗
NASA NTRS2018

An Educational Platform for Small Satellite Development with Proximity Operation Capabilities

An alternative to ground testing of small satellites is presented here, where the kinematics of a 3U underactuated CubeSat operating in 3 degrees-of-freedom (DOF) is reproduced by an omnidirectional wheeled platform, while satellite dynamics are simulated in real-time. The system is equipped with a relative navigation sensor in the form factor of a smartphone, the Smartphone Video Guidance Sensor (SVGS), allowing the platform to reproduce proximity operation maneuvers. The wheeled platform is used as an educational tool for students over a large range of academic levels, from high school to graduate school. A derivation of the kinematic relationship from satellite dynamics to rotacaster wheel velocities is presented, along with the guidance and control laws of the system. Simulation and experimental results demonstrate that the wheeled platform was able to successfully replicate detumble, slew, and attitude hold maneuvers of a 3U CubeSat.

Bertaska, Ivan R.↗
NASA NTRS2018

Starling1 - Mission Technologies Overview

The Starling series of demonstration missions will test technologies required to achieve affordable, distributed spacecraft ("swarm") missions that: are scalable to at least 100 spacecraft for applications that include synchronized multipoint measurements; involve closely coordinated ensembles of two or more spacecraft operating as a single unit for interferometric, synthetic aperture, or similar sensor architectures; or use autonomous or semi-autonomous operation of multiple spacecraft functioning as a unit to achieve science or other mission objectives with low-cost small spacecraft.Starling1 will focus on developing technologies that enable scalability and deep space application. The mission goals include the demonstration of a Mobile Ad-hoc NETwork (MANET) through an in-space communication experiment, vision based relative navigation through the Starling Formation-flying Optical eXperiment (StarFOX), and demonstration of autonomous spacecraft reconfiguration using technologies developed by the Distributed System Autonomy (DSA) project.

Cannon, Howard↗
NASA NTRS2017

The Lander Vision System for Mars 2020 Entry Descent and Landing

In January 2016, the Mars 2020 project added Terrain Relative Navigation to the project baseline. This new capability helps the mission avoid large hazards in the landing ellipse, which enables the consideration of landing sites that more geologically diverse than before. This diversity should improve the quality of the samples collected by Mars 2020 for possible future return to earth. The Lander Vision System (LVS) is the sensor that provides the position fix that is used to determine where to land between hazards identified in orbital data prior to landing. This paper describes the LVS flight design for Mars 2020, a high-fidelity simulation used as a design tool and the expected LVS performance for Mars 2020.

Johnson, Andrew↗
NASA NTRS2016

Environmental Design Implications for Deep Space SmallSats

The paper will describe the key technical drivers on the Sylph mission concept to explore a plume at Europa as a secondary free-flyer as a part of the planned Europa Mission. Sylph is a radiation-hardened smallsat concept that would utilize terrain relative navigation to fly at low altitudes through a plume, if found, and relay the mass spectra data back through the flyby spacecraft during its 24-hour mission. The second topic to be discussed will be the mission design constraints of the Near Earth Asterioid (NEA) Scout concept. NEAScout is a 6U cubesat that would utilize an 86 sq. m solar sail as propulsion to execute a flyby with a near-Earth asteroid and help retire Strategic Knowledge Gaps for future human exploration. NEAScout would cruise for 24 months to reach and characterize one Near-Earth asteroid that is representative of Human Exploration targets and telemeter that data directly back to Earth at the end of its roughly 2.5 year mission.

Kahn, Peter↗
NASA NTRS2019

Demonstration of Stereo Vision for Deorbit Descent and Landing

Planetary landers need to reduce velocity at low altitude for soft landing. Traditionally, estimating velocity and altitude has been performed with radar sensors whose performance meets the specific mission needs. There are not very many options for these sensors and they are difficult to include in a flight system either due to obsolescence, prohibitive cost or difficulty in accommodation. Recently, alternative sensing modalities are being pursued including Doppler LiDAR and vision. This paper describes results from a recent helicopter field test of a binocular stereo vision system for deorbit descent and landing applications. The system consisted of two 18.6 ̊ field of view cameras mounted 1.7m apart. Post processing of the images showed ranging accuracy better than 1% up to 500mand 17 cm/s velocimetry accuracy at 37m. For a flight system these images could be input into an FPGA-based processor which processes dense stereo and visual odometry in less than 1 second to achieve the stereo ranging frame rates required for soft landing. When coupled with vision based Terrain Relative Navigation this stereo system enables landing accuracies on the order of 10m.

Sternberg, David C.↗
NASA NTRS2020

Subscale Indoor Trajectory Testing via Six DOF Tendon-Actuated Robot

The NASA Johnson Space Center (JSC) Safe and Precise Landing – Integrated Capabilities Evolution (SPLICE) project is developing a large-scale six degree of freedom tendon-actuated robot (STAR). STAR is intended to reproduce lunar approach trajectories across subscale terrain in order to rapidly develop and test terrain relative and hazard relative navigation algorithms at low cost. NASA is interested in hosting external partners at the facility to enable them to advance their own algorithm development and testing and intends to activate the facility in Fall 2020. Contact us for more information.

Pedrotty, Samuel M.↗
NASA NTRS2020

SPLICE Safe and Precise Landing - Integrated Capabilities Evolution

The SPLICE project is developing, maturing, demonstrating, and infusing precision landing and hazard avoidance (PL&HA) technologies for NASA and potential commercial spaceflight missions. Near-term development includes high precision and accuracy velocimetry with ranging (via the NDL), high-resolution real-time mapping and hazard detection with ranging (via the HDL), lunar terrain relative navigation (TRN), and the requisite high performance computing capability. These technologies are initially intended to provide PL&HA for the moon, but are extensible to any planetary body. Long-term, the goal is to make these capabilities available to government and commercial entities and to license technology to commercial entities for production.

Pedrotty, Samuel M.↗
NASA NTRS2020

EDL Simulation Results for the Mars 2020 Landing Site Safety Assessment

The Mars 2020 rover is NASA’s next flagship mission, set to explore Mars in search of scientific evidence of past microbial life. Importantly, the rover will also, for the first time, have the ability to collect and cache rock and soil samples for retrieval and return to laboratories here on Earth. A key step in the development of the Mars 2020 mission is the selection of a suitable landing site with the largest likelihood of meeting scientific goals. This decision is a complex and critical one that requires close interaction between the scientific and engineering communities. The chosen landing site must be both scientifically interesting — providing the project with the greatest possible chance of gathering credible and defendable scientific evidence — and also safe enough to attempt a landing in the first place. Thus, arguably one of the most important undertakings of the Entry, Descent, and Landing (EDL) team, is to effectively enumerate, quantify, and communicate the landing risks to all of the stakeholders. The culmination of this effort is the Landing Site Safety Assessment, which is a review commissioned by the project, presided over by the EDL Standing Review Board, and attended by management and science stakeholders, in which the EDL team communicates their assessment of the associated landing risks and the statistical probability of a successful landing at each of the final candidate landing sites. This paper summarizes the results of high-fidelity computer simulations of the Mars 2020 EDL sequence used in this assessment. From an EDL performance perspective, all four candidates offer similar level of robustness, which is in-family with Mars Science Laboratory (MSL). However, two new features of the Mars 2020 EDL sequence – range trigger and Terrain-Relative Navigation (TRN) – dramatically enhance the capability of the EDL system to safely land at landing sites with much more rugged terrain than ever before considered. This has allowed the landing site selection for Mars 2020 to proceed in a manner that has been unprecedentedly weighted more heavily toward scientific interest and less heavily on engineering constraints. With TRN, the overall probability of success is predicted to be approximately 99% for all of the candidates.

David Way↗
NASA NTRS2019

Demonstration of stereo vision for deorbit descent and landing

This paper describes results from a recent helicopter field test of a binocular stereo vision system for deorbit descent and landing applications. The system consisted of two 18.6˚ field of view cameras mounted 1.7m apart. Post processing of the images showed ranging accuracy better than 1% up to 500m and 17 cm/s velocimetry accuracy at 37m. For a flight system these images could be input into an FPGA-based processor which processes dense stereo and visual odometry in less than 1 second to achieve the stereo ranging frame rates required for soft landing. When coupled with vision based Terrain Relative Navigation this stereo system enables landing accuracies on the order of 10m.

Johnson, Andrew E.↗
NASA NTRSDate not supplied

Mars 2020 – Landing a 1-ton rover and helicopter in an ancient Martian Lake

The Mars 2020 spacecraft launched in July 2020 and landed the Perseverance rover and Ingenuity helicopter successfully in Jezero crater on Feb. 18, 2021. Mars 2020 is the first stage of the Mars Sample Return campaign that will bring back the first samples from another planet to Earth. The entry, descent, and landing (EDL) sequence of the Mars 2020 spacecraft largely leveraged the previous Mars Science Laboratory (MSL) mission from 2012. Mars 2020 retained most of the EDL sequences of MSL, including active maneuvering during hypersonic flight to accurately target the landing site and use of the Skycrane descent stage that slowly lowered the rover while hovering above the ground. But Mars 2020 also added Terrain Relative Navigation, a machine vision-based system that allowed the spacecraft to navigate using an on-board camera that mapped ground landmarks to an on-board map, allowing the spacecraft to safely land in locations that were too hazardous for any previous Martian mission. Come hear about the “Seven Minutes of Terror” and the eight years of effort that went into the engineering behind the spacecraft.

Soumyo Dutta↗
NASA NTRSDate not supplied

Implementation of a Six Degree of Freedom Precision Lunar Landing Algorithm Using Dual Quaternion Representation

In this study, a powered descent guidance algorithm using a unit dual quaternion represen- tation of the vehicle dynamics is implemented in a high-fidelity simulation and on representative flight hardware. This Dual-Quaternion Guidance (DQG) algorithm is applied to the precision lunar landing problem which levies complex constraints upon the trajectory, including state triggered attitude constraints to enable terrain-relative navigation and hazard detection as well as real-time requirements for landing site re-designation. The investigation explores DQG’s usefulness as a mission design tool as well as a real-time guidance algorithm and defines real-time performance requirements for the hazard detection and avoidance (HDA) re-targeting phase of precision lunar landing. The experiment is presented in two parts. First, DQG is implemented within a high-fidelity Monte Carlo simulation to tune the algorithm’s parameters for the simulated vehicle, to refine the mission design, and to develop guidance update timing requirements to perform the HDA maneuver. DQG generates trajectories online for the divert which are tracked by the vehicle’s inner-loop controllers to the targeted landing site. Second, DQG is run on representative hardware to demonstrate real-time operation through a divert maneuver. These results allow for rapid, flexible, optimal mission design satisfying complex constraints, and for the definition of real-time performance requirements for the HDA operations inherent in precision lunar landing. The HDA divert maneuver is found to require guidance trajectory updates in less than three seconds. DQG is found to be too slow to meet this update timing on the descent and landing computer (DLC) in its current implementation. DQG running on alternative hardware can meet the update rate requirement. Algorithm implementation improvements are also recommended which are expected to speed up computation sufficiently to meet requirements on the DLC.

GN&C↗
NASA NTRS2022

Starling Animation

NASA’s Starling mission is advancing the readiness of various technologies for cooperative groups of spacecraft – also known as distributed missions, clusters, or swarms. Starling will demonstrate technologies to enable multipoint science data collection by several small spacecraft flying in swarms. The six-month mission will use four CubeSats in low-Earth orbit to test four technologies that let spacecraft operate in a synchronized manner without resources from the ground. The technologies will advance the following capabilities. • Network Communication • Cluster Flight Control • Relative navigation • Distributed Spacecraft Autonomy The Starling mission will test whether the technologies work as expected, what their limitations are, and what developments are still needed for CubeSat swarms to be successful. This animation illustrates Starling mission operations, offering an overview of each technology being demonstrated.

Howard N Cannon↗
NASA NTRSDate not supplied

Recent Results from Dragonfly Testing/Analysis as we head to PDR

Dragonfly is a relocatable lander mission to Saturn's moon Titan4, which as well as being a target of out-standing astrobiological interest as an organic-rich Ocean World, has the combination of low gravity (1/7 that of Earth) and a thick atmosphere (4x the density of Earth), making it an environment uniquely suitable for flight. Thus, the Dragonfly lander (similar in size to the Curiosity Mars rover) can take off using lift from a set of eight rotors and fly to a new landing site several kilometers away. The ability to perform such flights, lasting approximately 30 minutes, every month or so on Titan brings unprecedented mobility to planetary exploration, on a world known to have a diverse land-scape of dunes, craters and other features. Dragonfly is planned to launch in 2027, and following a nearly seven year interplanetary cruise would arrive at Titan by 2034. Due to the large scale height of the Titan atmosphere, Entry, Descent, and Landing (EDL) will be prolonged affair, taking nearly two hours to reach the surface. The ballistic entry environments that Dragonfly will be subjected to are fairly similar to that experienced by recent Mars missions; peak heating on the aeroshell will be about 300 W/sq.cm and peak deceleration is about 10g’s. Following the five minute entry segment, much of the remaining time is spent descending on the drogue and main para-chutes, which carry the dual role of decelerating the spacecraft and stabilizing the system during the long descent. While on one hand, this leisurely EDL sequence affords a relaxed timeline and plenty of time for event staging, it also provides ample opportunity for small disturbances to grow into potential flight safety risks, adding emphasis to the need for careful modeling, simulation and testing of key dynamic events. About two hours after entering the atmosphere, the nearly one metric ton rotocraft will be lowered approximately one meter out of the backshell (the ‘pose’ maneuver) to expose all eight rotors. The rotors will then be used to arrest any residual spin rate and prepare the system for transition to powered flight. Once despin is complete and the lander reaches a target altitude of 1.2 km above the surface (as verified by on-board lidar), the lander will be released and free fall for approximately one second before beginning controlled free flight. This entire “preparation for powered flight” process takes place over several minutes while the system is subject to the dynamic environment produced by so-called “wrist-mode” oscillations as the lander and backshell swing on the main parachute. Once in free flight, the lander will engage on-board terrain relative navigation to locate and navigate to a safe landing zone in the Shangri-La dune field south of Selk crater. Communication during this sequence will be limited to a series of direct-to-Earth X-band tones signalling key events and providing forensic information. Once on the ground, the lander will begin to send additional information, including data collected during this EDL sequence by the on-board Dragonfly Entry Aerosciences Measurements (DrEAM) instrumentation suite. This presentation will walk through the entry to first landing timeline in more detail, with a focus on recent analysis and testing results that inform system performance, margins and residual risk estimation.

Dragonfly↗