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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Performance Assessment of LunaNet’s Augmented Forward Signal

LunaNet provides a common set of interoperable specifications for communication and position, navigation and time (PNT) services and interfaces soon to be implemented in lunar vicinity. The LunaNet Interoperability Specification (LNIS) provides the design for the GNSS-like Augmented Forward Signal (AFS), which enables orbiting and surface users in lunar space, such as Artemis, to estimate their position, velocity, and time. The specification of AFS defines two orthogonal signal components on a single carrier: the in-phase component (AFS-I), a lower-chip-rate data channel tailored for applications where low SWaP (Size, Weight, and Power) is critical (e.g., IoT devices or search and rescue), and the quadrature component (AFS-Q), a high-chip-rate data-less pilot signal for high-precision, robust lunar navigation and positioning applications. An initial description of AFS was provided in LNIS 2023, with initial analysis results shown in Dafesh 2024 and Dafesh 2025, and the current signal in space description provided in LNIS 2025. As part of NASA's Lunar Communication Relay and Navigation Systems (LCRNS) project, this work expands upon the initial analysis results and proposes a new expanded set of AFS-Q spreading codes that exceed the cross-correlation and autocorrelation sidelobe performance of L1C and other GNSS signals, while providing additional expansion capabilities for future service satellites. A set of 420 codes was selected from a Weil-based code derived from the prime number 10247, which is larger than the 10243 prime number used to derive BeiDou’s B1C Weil sequences. Both the initial set of 210 codes and the expanded set of 420 codes are shown to provide the best cross-correlation of any 10230-chip satellite navigation codes. The performance is demonstrated for hierarchical sets of spreading codes optimized and organized in sets of 30 codes. The work also compares LunaNet’s AFS to terrestrial GNSS signals in terms of acquisition, tracking, and data demodulation performance. Performance is evaluated for receivers that only track the 1.023 MCPS data channel spreading code for low SWaP IoT use cases, as well as for receivers that track both the 1.023 MCPS data channel and the 5.115 MCPS pilot channel spreading code for high-performance use cases. Performance is assessed in the presence of interference and thermal noise. The analysis is performed in terms of expected operating conditions on the lunar surface. Several unique flexibility aspects of the augmented forward signal are described, including the use of the Q channel’s secondary and tertiary codes to enable variable coherent integrations during acquisition. This is compared to GNSS signals such as L5/E5 and MBOC in terms of achievable processing gain for interference mitigation versus acquisition complexity. The work details acquisition and tracking techniques used to optimally acquire and track the primary, secondary, and tertiary codes on the Q channel, as well as acquisition of the I channel spreading code. Acquisition of the 8 ms, Q channel spreading code is also compared to joint acquisition of the I and Q channel primary codes in noise and interference environments

LCRNS↗
NASA NTRSDate not supplied

Performance Assessment of LunaNet’s Augmented Forward Signal

LunaNet provides a common set of interoperable specifications for communication and position, navigation and time (PNT) services and interfaces soon to be implemented in lunar vicinity. The LunaNet Interoperability Specification (LNIS) provides the design for the GNSS-like Augmented Forward Signal (AFS), which enables orbiting and surface users in lunar space, such as Artemis, to estimate their position, velocity, and time. The specification of AFS defines two orthogonal signal components on a single carrier: the in-phase component (AFS-I), a lower-chip-rate data channel tailored for applications where low SWaP (Size, Weight, and Power) is critical (e.g., IoT devices or search and rescue), and the quadrature component (AFS-Q), a high-chip-rate data-less pilot signal for high-precision, robust lunar navigation and positioning applications. An initial description of AFS was provided in [1], with initial analysis results shown in [2] and [3] and the current signal in space description provided in [4]. As part of NASA's Lunar Communication Relay and Navigation Systems (LCRNS) project, this work expands upon the initial analysis results and proposes a new expanded set of AFS-Q spreading codes that exceed the cross-correlation and autocorrelation sidelobe performance of L1C and other GNSS signals, while providing additional expansion capabilities for future provider satellites. A set of 420 codes was selected from a Weil-based code derived from the prime number 10247, which is larger than the 10243 prime number used to derive Beidou’s B1C Weil sequences. Both the initial set of 210 codes and the expanded set of 420 codes are shown to provide the best cross-correlation of any 10230-chip satellite navigation codes. The performance is demonstrated for hierarchical sets of spreading codes optimized and organized in sets of 30 codes. The new codes were developed using an optimization approach and correlation methodology described in [5]. The work also compares LunaNet’s AFS to terrestrial GNSS signals in terms of acquisition, tracking, and data demodulation performance. Performance is evaluated for receivers that only track the 1.023 MCPS data channel spreading code for low SWaP IoT use cases, as well as for receivers that track both the 1.023 MCPS data channel and the 5.115 MCPS pilot channel spreading code for high-performance use cases. Performance is assessed in the presence of interference and thermal noise. The analysis is performed in terms of expected operating conditions on the lunar surface. Several unique flexibility aspects of the augmented forward signal are described, including the use of the Q channel’s secondary and tertiary codes to enable variable coherent integrations during acquisition. This is compared to GNSS signals such as L5/E5 and MBOC in terms of achievable processing gain for interference mitigation versus acquisition complexity. The work details acquisition and tracking techniques used to optimally acquire and track the primary, secondary, and tertiary codes on the Q channel, as well as acquisition of the I channel spreading code. Acquisition of the 8 ms Q channel spreading code is also compared to joint acquisition of the I and Q channel primary codes in noise and interference environments.

LCRNS↗
NASA NTRS1977

Installation package for air flat plate collector

The Solar 2 dimensions are four feet by eight feet by two and one half inches. The collector weighs 130 pounds and has an effective solar collection area of over 29.5 square feet. This area represents 95 percent of the total surface of the collector. The installation, operation and maintenance manual, safety hazard analysis, special handling instructions, materials list, installation concept drawings, warranty and certification statement are included in the installation package.

Source record↗
NASA NTRS1994

Sample Acquisition and Instrument Deployment (SAID)

This report details the interim progress for contract NASW-4818, Sample Acquisition and Instrument Deployment (SAID), a robotic system for deploying science instruments and acquiring samples for analysis. The system is a conventional four degree of freedom manipulator 2 meters in length. A baseline design has been achieved through analysis and trade studies. The design considers environmental operating conditions on the surface of Mars, as well as volume constraints on proposed Mars landers. Control issues have also been studied, and simulations of joint and tip movements have been performed. A passively braked shape memory actuator with the ability to measure load has been developed. The wrist also contains a mechanism which locks the lid output to the bucket so that objects can be grasped and released for instrument deployment. The wrist actuator has been tested for operational power and mechanical functionality at Mars environmental conditions. The torque which the actuator can produce has been measured. Also, testing in Mars analogous soils has been performed.

Boyd, Robert C.↗
NASA NTRS1995

Sample acquisition and instrument deployment

Progress is reported in developing the Sample Acquisition and Instrument Deployment (SAID) system, a robotic system for deploying science instruments and acquiring samples for analysis. The system is a conventional four degree of freedom manipulator 2 meters in length. A baseline design has been achieved through analysis and trade studies. The design considers environmental operating conditions on the surface of Mars, as well as volume constraints on proposed Mars landers. Control issues have also been studied, and simulations of joint and tip movements have been performed. The systems have been fabricated and tested in environmental chambers, as well as soil testing and robotic control testing.

Boyd, Robert C.↗
NASA NTRS2014

Vision Based Autonomous Robotic Control for Advanced Inspection and Repair

The advanced inspection system is an autonomous control and analysis system that improves the inspection and remediation operations for ground and surface systems. It uses optical imaging technology with intelligent computer vision algorithms to analyze physical features of the real-world environment to make decisions and learn from experience. The advanced inspection system plans to control a robotic manipulator arm, an unmanned ground vehicle and cameras remotely, automatically and autonomously. There are many computer vision, image processing and machine learning techniques available as open source for using vision as a sensory feedback in decision-making and autonomous robotic movement. My responsibilities for the advanced inspection system are to create a software architecture that integrates and provides a framework for all the different subsystem components; identify open-source algorithms and techniques; and integrate robot hardware.

sensory feedback↗
NASA NTRSDate not supplied

The Application of Remote Sensing using NASA Earth Observations paired with Sociodemographic Indicators to Identify Communities Most Susceptible to Urban Heat Exposure in Austin, Texas

In recent years, Austin, Texas has experienced an increase in population and urban development. Additionally, the City’s climate—already characterized by periods of extreme heat and drought—continues to change. As temperatures and demand for utilities and cooling resources rise, the number of heat-related deaths and illnesses in socially vulnerable populations (e.g., older, lower-income populations) is expected to increase. The City of Austin, The University of Texas at Austin (UT Austin), and The University of Texas Health Science Center at Houston (UT Health) partnered with NASA DEVELOP to examine the distribution of urban heat throughout the City. This project used land surface temperature, greenness, plant water content, and urban surface material analysis parameters derived from NASA Earth observations from Landsat 8 Operational Land Imager (OLI), Landsat 8 Thermal Infrared Sensor (TIRS), and Aqua and Terra Moderate Resolution Imaging Spectroradiometer (MODIS). The project team produced three different indices to create a spatial analysis for the study area including a social vulnerability index (SoVI), heat exposure index (HEI), and an overall heat priority index (HPI) score. This overall score was determined with a weighted analysis of heat-related environmental variables from NASA Earth observations and socioeconomic data from the 2019 American Community Survey. Based on the HPI score, the project team identified 121 census block groups out of 605 total that are designated as being most at risk of adverse impacts from extreme heat events. To test the sensitivity of the HPI, the team used a Monte Carlo analysis using different approaches for geographic scale, variable inclusion, census uncertainty, and index aggregation. Based on the sensitivity analysis, the resulting HPI score showed the metric was consistent with the baseline HPI. This provided increased confidence the score can be used as a tool to make informed infrastructure improvement plans in targeted areas (e.g., siting of cooling centers) and ensure equitable sustainable development.

Ryan Hammock↗
NASA NTRSDate not supplied

Extending the Duration of Crewed Stays on the Lunar Surface

NASA’s Artemis missions aim to return humans to the Moon for the first time since the Apollo Program. Unlike the Apollo missions, Artemis missions will take advantage of pre-emplaced assets on the lunar surface to support crewed exploration, science, and utilization. Although the initial Artemis surface missions are intended to keep crew on the lunar surface for durations ranging from several days to several weeks, crewed stays of longer periods may provide additional support toward NASA’s Moon to Mars Objectives, including long-term exploration and continuous human lunar presence. If mission durations are extended beyond the expected few weeks, the elements and concepts of operation for the lunar architecture will need to be capable of supporting that extension. This paper uses an integrated systems analysis perspective to examine the architectural considerations of extending the duration of human missions on the lunar surface. By identifying these key architectural considerations, this paper offers insight into how elements and operations might meet the demands of potential future mission concepts. This paper does not recommend changes to NASA’s lunar architecture, and it does not evaluate whether any mission concepts affect the relative satisfaction of the Moon to Mars Objectives. However, if crew do remain on the surface for progressively longer periods of time, the functions and capabilities provided by the assets supporting the crew may need to adjust to support the needs of those missions. The functions and capabilities identified as key to enable such extended duration missions include power generation and storage, logistics delivery, radiation mitigation, provision of medical and exercise capability, abort from the lunar surface, maintenance, and the provision of pressurized volume. For example, the medical capabilities available to the crew may become more extensive, and habitable elements may need to change to support longer crewed periods (and shorter quiescent periods). In some cases, these changes may be accomplished through alterations to use cases, operational changes, or the evolution of lunar surface elements, but in other cases, new elements may be preferable. By identifying key considerations for the functions and capabilities of notional lunar surface elements as the length of each crewed mission is extended from several days to continuous human presence on the Moon, this paper assesses how the elements of NASA’s lunar architecture might support the extension of mission durations. In addition, this analysis can help inform future evaluation of whether such extended duration missions improve NASA’s ability to address its Moon to Mars Objectives.

Garrett M. Carman↗
NASA NTRS1988

Analysis of a used pair of arcjet electrodes

The anode and cathode of a 30-kW class arcjet engine have been sectioned and analyzed. This arcjet was operated for a total time of 573 hours at power levels between 25 and 30 kW with ammonia at flow rates of 0.25 and 0.27 gm/s. The accumulated run time was sufficient to clearly establish erosion patterns and their causes. The type of electron emission from various parts of the cathode surface was made clear by Scanning Electron Microscope analysis. A Scanning Electron Microscope was used to study recrystallization on the hot anode surface. These electrodes were made of 2 percent thoriated tungsten and the surface thorium content and gradient perpendicular to the surfaces was determined by quantitative microprobe analysis. The results of this material analysis on the electrodes and recommendations for improving electrode operational life time are presented.

Pivirotto, Thomas J.↗
NASA NTRS1983

LANDSAT-4 image data quality analysis for energy related applications

No useable LANDSAT 4 TM data were obtained for the Hanford site in the Columbia Plateau region, but TM simulator data for a Virginia Electric Company nuclear power plant was used to test image processing algorithms. Principal component analyses of this data set clearly indicated that thermal plumes in surface waters used for reactor cooling would be discrenible. Image processing and analysis programs were successfully testing using the 7 band Arkansas test scene and preliminary analysis of TM data for the Savanah River Plant shows that current interactive, image enhancement, analysis and integration techniques can be effectively used for LANDSAT 4 data. Thermal band data appear adequate for gross estimates of thermal changes occurring near operating nuclear facilities especially in surface water bodies being used for reactor cooling purposes. Additional image processing software was written and tested which provides for more rapid and effective analysis of the 7 band TM data.

Wukelic, G. E.↗
NASA NTRSDate not supplied

Ensuring Safe Decision-Making on the Moon and Mars: Cognitive Performance Assessment for Exploration Class Mission EVA

Extravehicular activity (EVA) is one of the most dangerous and cognitively demanding actions that astronauts can execute, and the cognitive demands associated with future partial gravity EVAs on the Moon and Mars are expected to be higher compared to microgravity EVAs currently conducted from the International Space Station. Decrements in cognitive performance present an important risk to crew safety during exploration mission class EVA. Yet there is currently insufficient data to characterize cognitive performance prior to, during, and following EVA. Furthermore, it is still unclear which cognitive domains are most important for conducting mission critical decisions with crew safety implications. To address this gap, we conducted a cognitive task analysis (CTA) of EVA to characterize the procedures, the cognitive demands required, and the critical safety decisions associated with decrements in cognitive performance. We conducted a cognitive task analysis with 15 astronauts and subject matter experts in EVA operations and research. Interviews focused on surface exploration EVA and elicited feedback from experts on the cognitive skills required for specific EVA tasks, including cognitive strategies, critical cues, and decision-making strategies. A cognitive demands table was assembled to consolidate and synthesize the information from all interviews. The information from this cognitive task analysis informs ongoing exploration EVA for Moon to Mars. This work identifies the specific cognitive challenges that astronauts are likely to encounter during surface exploration EVA, and provides the foundation for: (1) prioritized and targeted cognitive performance measurement and functional performance tests, (2) EVA simulation design at varying levels of cognitive workload, and (3) the development of training and other technologies that can improve safe decision-making and inform EVA planning on future spaceflight missions to the Moon and Mars.

Steven R Anderson↗
NASA NTRS2011

Autonomous Aerobraking: Thermal Analysis and Response Surface Development

A high-fidelity thermal model of the Mars Reconnaissance Orbiter was developed for use in an autonomous aerobraking simulation study. Response surface equations were derived from the high-fidelity thermal model and integrated into the autonomous aerobraking simulation software. The high-fidelity thermal model was developed using the Thermal Desktop software and used in all phases of the analysis. The use of Thermal Desktop exclusively, represented a change from previously developed aerobraking thermal analysis methodologies. Comparisons were made between the Thermal Desktop solutions and those developed for the previous aerobraking thermal analyses performed on the Mars Reconnaissance Orbiter during aerobraking operations. A variable sensitivity screening study was performed to reduce the number of variables carried in the response surface equations. Thermal analysis and response surface equation development were performed for autonomous aerobraking missions at Mars and Venus.

Dec, John A.↗
NASA NTRS2015

Identification and Analysis of National Airspace System Resource Constraints

This analysis is the deliverable for the Airspace Systems Program, Systems Analysis Integration and Evaluation Project Milestone for the Systems and Portfolio Analysis (SPA) focus area SPA.4.06 Identification and Analysis of National Airspace System (NAS) Resource Constraints and Mitigation Strategies. "Identify choke points in the current and future NAS. Choke points refer to any areas in the en route, terminal, oceanic, airport, and surface operations that constrain actual demand in current and projected future operations. Use the Common Scenarios based on Transportation Systems Analysis Model (TSAM) projections of future demand developed under SPA.4.04 Tools, Methods and Scenarios Development. Analyze causes, including operational and physical constraints." The NASA analysis is complementary to a NASA Research Announcement (NRA) "Development of Tools and Analysis to Evaluate Choke Points in the National Airspace System" Contract # NNA3AB95C awarded to Logistics Management Institute, Sept 2013.

Smith, Jeremy C.↗
NASA NTRS1994

Mars vertical axis wind machines: The design of a tornado vortex machine for use on Mars

Ever since Viking 1 and 2 landed on the surface of Mars in the summer of 1976, man has yearned to go back. But before man steps foot upon the surface of Mars, unmanned missions such as the Martian Soft Lander and Martian Subsurface Penetrator will precede him. Alternative renewable power sources must be developed to supply the next generation of surface exploratory spacecraft, since RTG's, solar cells, and long-life batteries all have their significant drawbacks. One such alternative is to take advantage of the unique Martian atmospheric conditions by designing a small scale, Martian wind power generator, capable of surviving impact and fulfilling the long term (2-5 years), low-level power requirements (1-2 Watts) of an unmanned surface probe. After investigation of several wind machines, a tornado vortex generator was chosen based upon its capability of theoretically augmenting and increasing the available power that may be extracted from average Martian wind speeds of approximately 7.5 m/s. The Martian Tornado Vortex Wind Generator stands 1 meter high and has a diameter of 0.5 m. Martian winds enter the base and shroud of the Tornado Vortex Generator at 7.5 m/s and are increased to an exit velocity of 13.657 m/s due to the vortex that is created. This results in a rapid pressure drop of 4.56 kg/s(exp 2) m across the vortex core which aids in producing a net power output of 1.1765 Watts. The report contains the necessary analysis and requirements needed to feasibly operate a low-level powered, unmanned, Martian surface probe.

Carlin, Daun↗
NASA NTRSDate not supplied

Updated Human Mars Ascent Vehicle Concept in Support of NASA’s Strategic Analysis Cycle 2021

The NASA Artemis program has brought significant change to the agency’s human exploration strategy over the last several years. The human exploration of Mars remains an ultimate objective of the overall human exploration strategy. However, how the agency intends to execute initial human exploration of Mars has shifted to better align with current policy. These changes find their way into the design of key architecture elements, such as the Mars Ascent Vehicle (MAV). Of the numerous changes in the conceptual human Mars architecture, two in particular have had significant impact on the design of the human MAV: the desire for minimal surface infrastructure for initial human Mars missions, and technology investment timelines in support of initial human missions to Mars. The first leads to a surface mission architecture targeting a 30-day surface duration with two crewmembers. The second drives out in-situ resource utilization (ISRU) from the initial sortie. As a result, the reference MAV design for initial human Mars missions in the Human Exploration and Operations Mission Directorate’s Strategic Analysis Cycle 2021 (SAC21) is based around supporting the return of 2 crew from the surface of Mars, without surface ISRU. This has led to several design changes since 2019, when details of a reference human MAV were last published. The MAV concept for SAC21 consists of a two-stage vehicle capable of supporting two crew for 84 hours. This duration is derived from a baseline ascent trajectory targeting an apoapsis rendezvous with the habitation element in a nominal 5-sol Mars aggregation orbit. With the goal of minimizing technology investments for the initial surface sortie removing ISRU from the trade space, the MAV must now be landed either fully loaded with propellant, or with some portion of the propellant off-loaded. Landing a partially-fueled MAV will require additional surface assets to perform robotic propellant transfer on the surface of Mars from a pre-emplaced propellant depot. Furthermore, cryogenic fluid management and storage for extended duration with no losses represents additional technology investment that would have to be made to support cryogenic-based propellant concepts that have been the baseline in past architectures. As a result, the SAC21 architecture utilizes a storable propellant-based MAV propulsion system to minimize these potential technology investments incurred by cryogenic-based propulsion systems. Recent efforts also focused on evaluating the sensitivity of key design parameters, such as landing site latitude, elevation, and local atmospheric conditions. All play a large role in determining the predicted propellant requirements of the MAV. Understanding their potential impacts is important because of the rippling effects of changes to the MAV design on other architecture elements, such as entry, descent, landing, and transportation systems. Results indicate up to +2% to -4% wet mass variation due to landing site latitude, with higher latitudes greater than 70 degrees North resulting in greater than 6% wet mass increases. The MAV saw reduced impact due to atmospheric design parameters, which only accounting for -0.6% to +0.4% wet mass variation.

Douglas J. Trent↗
NASA NTRS1997

Rotational Energy Transfer of N2 Gas Determined Using a New Ab Initio Potential Energy Surface

Rotational energy transfer between two N2 molecules is a fundamental process of some importance. Exchange is expected to play a role, but its importance is somewhat uncertain. Rotational energy transfer cross sections of N2 also have applications in many other fields including modeling of aerodynamic flows, laser operations, and linewidth analysis in nonintrusive laser diagnostics. A number of N2-N2 rigid rotor potential energy surface (PES) has been reported in the literature.

Huo, Winifred M.↗
NASA NTRS1991

A mission design for International Manned Mars Mission - From the 1991 International Space University (ISU) Design Project

The International Space University (ISU) conducted a study of an international program to support human exploration of Mars as its annual Design Project activity during its 1991 summer session in Toulouse, France. Although an ISU Design Project strives to produce an in-depth analysis during the intense 10-week summer session, the International Mars Mission (IMM) project was conducted in a manner designed to provide a learning experience for young professionals working in an unusual multidisciplinary and multinational environment. The breadth of the IMM study exceeds that of most Mars mission studies of the past, encompassing political organization for long-term commitment, multinational management structure, cost analysis, mission architecture, vehicle configuration, crew health, life support, Mars surface infrastructure, mission operations, technology evaluation, risk assessment, scientific planning, exploration, communication networks, and Martian resource utilization. The IMM Final Report has particular value for those seeking insight into the choices made by a multinational group working in an apolitical environment on the problems of international cooperation in space.

Mendell, Wendell W.↗
NASA NTRS2000

Thermal and Evolved Gas Analysis of Hydromagnesite and Nesquehonite: Implications for Remote Thermal Analysis on Mars

Volatile-bearing minerals (e.g., Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates) may be important phases on the surface of Mars. In order to characterize these potential phases the Thermal Evolved-Gas Analyzer (TEGA), which was onboard the Mars Polar Lander, was to have performed differential scanning calorimetry (DSC) and evolved-gas analysis of soil samples collected from the surface. The sample chamber in TEGA operates at about 100 mbar (approximately 76 torr) with a N2, carrier gas flow of 0.4 seem. Essentially, no information exists on the effects of reduced pressure on the thermal properties of volatile-bearing minerals. In support of TEGA, we have constructed a laboratory analog for TEGA from commercial instrumentation. We connected together a commercial differential scanning calorimeter, a quadruple mass spectrometer, a vacuum pump, digital pressure gauge, electronic mass flow meter, gas "K" bottles, gas dryers, and high and low pressure regulators using a collection of shut off and needle valves. Our arrangement allows us to vary and control the pressure and carrier gas flow rate inside the calorimeter oven chamber.

Lauer, H. V., Jr.↗