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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Reliability Considerations for Ultra- Low Power Space Applications

NASA, the aerospace community, and other high reliability (hi-rel) users of advanced microelectronic products face many challenges as technology continues to scale into the deep sub- micron region and ULP devices are sought after. Technology trends, ULP microelectronics, scaling and performance tradeoffs, reliability considerations, and spacecraft environments will be presented from a ULP perspective for space applications.

reliability↗
NASA NTRS2013

Human Exploration of Near-Earth Asteroids and Sample Collection Considerations

In 2009 the Augustine Commission identified near-Earth asteroids (NEAs) as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. Subsequently, the U.S. presidential administration directed NASA on April 15, 2010 to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. Human Exploration Considerations: These missions would be the first human expeditions to interplanetary bodies beyond the Earth-Moon system and would prove useful for testing technologies required for human missions to Mars, Phobos and Deimos, and other Solar System destinations. Missions to NEAs would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific examinations of these primitive objects. However, prior to sending human explorers to NEAs, robotic investigations of these bodies would be required in order to maximize operational efficiency and reduce mission risk. These precursor missions to NEAs would fill crucial strategic knowledge gaps concerning their physical characteristics that are relevant for human exploration of these relatively unknown destinations. Sample Science Benefits: Information obtained from a human investigation of a NEA, together with ground-based observations and prior spacecraft investigations of asteroids and comets, will also provide a real measure of ground truth to data obtained from terrestrial meteorite collections. Major advances in the areas of geochemistry, impact history, thermal history, isotope analyses, mineralogy, space weathering, formation ages, thermal inertias, volatile content, source regions, solar system formation, etc. can be expected from human NEA missions. Samples directly returned from a primitive body would lead to the same kind of breakthroughs for understanding NEAs that the Apollo samples provided for understanding the Earth-Moon system and its formation history. International Participation: In addition, robotic precursor and human exploration missions to NEAs would allow the NASA and its international partners to gain operational experience in performing complex tasks (e.g., sample collection, deployment of payloads, retrieval of payloads, etc.) with crew, robots, and spacecraft under microgravity conditions at or near the surface of a small body. This would provide an important synergy between the worldwide Science and Exploration communities, which will be crucial for development of future international deep space exploration architectures and has potential benefits for future exploration of other destinations beyond low-Earth orbit.

Abell, Paul↗
NASA NTRS2014

Dust Interactions on Small Solar System Bodies and Technology Considerations for Exploration

Small‐bodies such as asteroids and Mars' moons Phobos and Deimos have relatively unknown regolith environments. It is hypothesized that dust preserved in the regolith on the surfaces will have similar mechanical properties to lunar dust because of similar formation processes from micrometeorite bombardment, low relative gravity for slow settling times, and virtually no weathering because there is no atmosphere. This combination of processes infers that small‐body dust particles will be highly angular and retain abrasive properties. The focus of this paper uses the mission architecture and engineering design for an asteroid hopper known as Hedgehog, a spherical spacecraft with several symmetric spikes used to aid with tumbling mobility in a low gravity environment. Dust abrasion considerations are highlighted throughout the paper relating to the lead authors' previous work, but act as an example of one of many important dust or regolith physical properties that need to be considered for future exploration. Measurable regolith properties are summarized in order to identify technologies that may be useful for exploration in terms of scientific return and spacecraft design. Previous instruments are summarized in this paper that could be used on the Hedgehog. Opportunities for hardware payloads are highlighted that include low mass solutions or dualpurpose instruments that can measure regolith or dust properties. Finally, dust mitigation suggestions are made for vehicles of this mobility profile.

Kobrick, Ryan,↗
NASA NTRS2014

Spacecraft Hybrid Control At NASA: A Look Back, Current Initiatives, and Some Future Considerations

There is a heightened interest within NASA for the design, development, and flight implementation of mixed actuator hybrid attitude control systems for science spacecraft that have less than three functional reaction wheel actuators. This interest is driven by a number of recent reaction wheels failures on aging, but still scientifically productive, NASA spacecraft. This paper describes the highlights of the first NASA Cross-Center Hybrid Control Workshop that was held in Greenbelt, Maryland in April of 2013 under the sponsorship of the NASA Engineering and Safety Center (NESC). A brief historical summary of NASA's past experiences with spacecraft mixed actuator hybrid attitude control approaches, some of which were implemented on-orbit, will be provided. This paper will also convey some of the lessons learned and best practices captured at that workshop. Some relevant recent and current hybrid control activities will be described with an emphasis on work in support of a repurposed Kepler spacecraft. Specific technical areas for future considerations regarding spacecraft hybrid control will also be identified.

attitude control↗
NASA NTRS2013

Practical Considerations for Using Constant Force Springs in Space-Based Mechanisms

Mechanical springs are a common element in mechanism from all walks of life; cars, watches, appliances, and many others. These springs generally exhibit a linear relationship between force and deflection. In small mechanisms, deflections are small so the variation in spring force between one position and another are generally small and do not influence the design or functionality of the device. However, as the spacecraft industry drives towards larger, deployable satellites, the distances a spring or springs must function over can become considerable so much so that the structural integrity of the device may be impacted. As such, an increasingly common mechanism element is the constant force spring- one that provides a constant force regardless of deflection. These elements are commonly in the conceptual design phase to deal with system-level large deflections, but in the detailed design or integration test phase they can pose significant implementation issues. This article addresses some of the detailed issues in order for these constant force springs to be properly designed into space systems.

reliability testing↗
NASA NTRS2015

Human Performance Considerations for Remotely Piloted Aircraft Systems (RPAS)

Successful integration of Remotely Piloted Aircraft Systems (RPAS) into civil airspace will not only require solutions to technical challenges, but will also require that the design and operation of RPAS take into account human limitations and capabilities. Human factors can affect overall system performance whenever the system relies on people to interact with another element of the system. Four types of broad interactions can be described. These are (1) interactions between people and hardware, such as controls and displays; (2) human use of procedures and documentation; (3) impact of the task environment, including lighting, noise and monotony; and lastly, (4) interactions between operational personnel, including communication and coordination. In addition to the human factors that have been identified for conventional aviation, RPAS operations introduce a set of unique human challenges. The purpose of document is to raise human factors issues for consideration by workgroups of the ICAO RPAS panel as they work to develop guidance material and additions to ICAO annexes. It is anticipated that the content of this document will be revised and updated as the work of the panel progresses.

ICAO↗
NASA NTRS2015

Characterization of Vacuum Facility Background Gas Through Simulation and Considerations for Electric Propulsion Ground Testing

The background gas in a vacuum facility for electric propulsion ground testing is examined in detail through a series of cold flow simulations using a direct simulation Monte Carlo (DSMC) code. The focus here is on the background gas itself, its structure and characteristics, rather than assessing its interaction and impact on thruster operation. The background gas, which is often incorrectly characterized as uniform, is found to have a notable velocity within a test facility. The gas velocity has an impact on the proper measurement of pressure and the calculation of ingestion flux to a thruster. There are also considerations for best practices for tests that involve the introduction of supplemental gas flows to artificially increase the background pressure. All of these effects need to be accounted for to properly characterize the operation of electric propulsion thrusters across different ground test vacuum facilities.

Test Facilities↗
NASA NTRS2013

Preliminary Design Considerations for Access and Operations in Earth-Moon L1/L2 Orbits

Within the context of manned spaceflight activities, Earth-Moon libration point orbits could support lunar surface operations and serve as staging areas for future missions to near-Earth asteroids and Mars. This investigation examines preliminary design considerations including Earth-Moon L1/L2 libration point orbit selection, transfers, and stationkeeping costs associated with maintaining a spacecraft in the vicinity of L1 or L2 for a specified duration. Existing tools in multi-body trajectory design, dynamical systems theory, and orbit maintenance are leveraged in this analysis to explore end-to-end concepts for manned missions to Earth-Moon libration points.

Folta, David C.↗
NASA NTRS2016

Safety and Certification Considerations for Expanding the Use of UAS in Precision Agriculture

The agricultural community is actively engaged in adopting new technologies such as unmanned aircraft systems (UAS) to help assess the condition of crops and develop appropriate treatment plans. In the United States, agricultural use of UAS has largely been limited to small UAS, generally weighing less than 55 lb and operating within the line of sight of a remote pilot. A variety of small UAS are being used to monitor and map crops, while only a few are being used to apply agricultural inputs based on the results of remote sensing. Larger UAS with substantial payload capacity could provide an option for site-specific application of agricultural inputs in a timely fashion, without substantive damage to the crops or soil. A recent study by the National Aeronautics and Space Administration (NASA) investigated certification requirements needed to enable the use of larger UAS to support the precision agriculture industry. This paper provides a brief introduction to aircraft certification relevant to agricultural UAS, an overview of and results from the NASA study, and a discussion of how those results might affect the precision agriculture community. Specific topics of interest include business model considerations for unmanned aerial applicators and a comparison with current means of variable rate application. The intent of the paper is to inform the precision agriculture community of evolving technologies that will enable broader use of unmanned vehicles to reduce costs, reduce environmental impacts, and enhance yield, especially for specialty crops that are grown on small to medium size farms.

Hayhurst, Kelly J.↗
NASA NTRS2016

Beam Wave Considerations for Optical Link Budget Calculations

The bounded beam wave nature of electromagnetic radiation emanating from a finite size aperture is considered for diffraction-based link power budget calculations for an optical communications system. Unlike at radio frequency wavelengths, diffraction effects are very important at optical wavelengths. In the general case, the situation cannot be modeled by supposing isotropic radiating antennas and employing the concept of effective isotropic radiated power. It is shown here, however, that these considerations are no more difficult to treat than spherical-wave isotopic based calculations. From first principles, a general expression governing the power transfer for a collimated beam wave is derived and from this are defined the three regions of near-field, first Fresnel zone, and far-field behavior. Corresponding equations for the power transfer are given for each region. It is shown that although the well-known linear expressions for power transfer in the far-field hold for all distances between source and receiver in the radio frequency case, nonlinear behavior within the first Fresnel zone must be accounted for in the optical case at 1550 nm with typical aperture sizes at source/receiver separations less that 100 km.

Wave Propagation↗
NASA NTRS2017

Programmatic Considerations to Reduce the Risk of Adverse Renal Stone Events in Spaceflight

Introduction: Microgravity exposure may alter the likelihood that astronauts will experience renal stones. The potential risk includes both acute and chronic health issues, with the potential for significant impact on mission objectives. Methods: To understand the role of the NASA's Human Research Program (HRP) research agenda in both preventing and addressing renal stones in spaceflight, current astronaut epidemiologic data and a summary of programmatic considerations are reviewed. Results: Although there has never been a symptomatic renal stone event in a U.S. crewmember during spaceflight, urine chemistry has been altered - likely due to induced changes in renal physiology as a result of exposure to microgravity. This may predispose astronauts to stone formation, leading the HRP to conduct and sponsor research to: 1) understand the risk of stone formation in space; 2) prevent stones from forming; and 3) address stones that may form by providing novel diagnostic and therapeutic approaches. Discussion: The development of a renal stone during spaceflight is a significant medical concern that requires the HRP to minimize this risk by providing the ability to prevent, diagnose, monitor and treat the condition during spaceflight. A discussion of the risk as NASA understands it is followed by an overview of the multiple mitigations currently under study, including novel ultrasound techniques for stone detection and manipulation, and how they may function as part of a larger exploration medical system.

Antonsen, Erik↗
NASA NTRS2016

Radiation-Induced Backgrounds in Astronomical Instruments: Considerations for Geosynchronous Orbit and Implications for the Design of the WFIRST Wide-Field Instrument

Geosynchronous orbits are appealing for solar or astrophysical observatories because they permit continuous data downlink at high rates. The radiation environment in these orbits presents unique challenges, however. This paper describes both the characteristics of the radiation environment in geosynchronous orbit and the mechanisms by which this radiation generates backgrounds in photon detectors. Shielding considerations are described, and a preliminary shielding design for the proposed Wide-Field InfraRed Survey Telescope observatory is presented as a reference for future space telescope concept studies that consider a geosynchronous orbit.

Kruk, Jeffrey W.↗
NASA NTRS2016

Optical Telescope System-Level Design Considerations for a Space-Based Gravitational Wave Mission

The study of the Universe through gravitational waves will yield a revolutionary new perspective on the Universe, which has been intensely studied using electromagnetic signals in many wavelength bands. A space-based gravitational wave observatory will enable access to a rich array of astrophysical sources in the measurement band from 0.1 to 100 mHz, and nicely complement observations from ground-based detectors as well as pulsar timing arrays by sampling a different range of compact object masses and astrophysical processes. The observatory measures gravitational radiation by precisely monitoring the tiny change in the proper distance between pairs of freely falling proof masses. These masses are separated by millions of kilometers and, using a laser heterodyne interferometric technique, the change in their proper separation is detected to approx. 10 pm over timescales of 1000 seconds, a fractional precision of better than one part in 10(exp 19). Optical telescopes are essential for the implementation of this precision displacement measurement. In this paper we describe some of the key system level design considerations for the telescope subsystem in a mission context. The reference mission for this purpose is taken to be the enhanced Laser Interferometry Space Antenna mission (eLISA), a strong candidate for the European Space Agency's Cosmic Visions L3 launch opportunity in 2034. We will review the flow-down of observatory level requirements to the telescope subsystem, particularly pertaining to the effects of telescope dimensional stability and scattered light suppression, two performance specifications which are somewhat different from the usual requirements for an image forming telescope.

LISA↗
NASA NTRS2017

Considerations for GPU SEE Testing

This presentation will discuss the considerations an engineer should take to perform Single Event Effects (SEE) testing on GPU devices. Notable topics will include setup complexity, architecture insight which permits cross platform normalization, acquiring a reasonable detail of information from the test suite, and a few lessons learned from preliminary testing.

NASA Electronic Parts and Packaging (NEPP) Program↗
NASA NTRS2017

Design Considerations for Attitude State Awareness and Prevention of Entry into Unusual Attitudes

Loss of control - inflight (LOC-I) has historically represented the largest category of commercial aviation fatal accidents. A review of the worldwide transport airplane accidents (2001-2010) evinced that loss of attitude or energy state awareness was responsible for a large majority of the LOC-I events. A Commercial Aviation Safety Team (CAST) study of 18 worldwide loss-of-control accidents and incidents determined that flight crew loss of attitude awareness or energy state awareness due to lack of external visual reference cues was a significant causal factor in 17 of the 18 reviewed flights. CAST recommended that "Virtual Day-Visual Meteorological Condition" (Virtual Day-VMC) displays be developed to provide the visual cues necessary to prevent loss-of-control resulting from flight crew spatial disorientation and loss of energy state awareness. Synthetic vision or equivalent systems (SVS) were identified for a design "safety enhancement" (SE-200). Part of this SE involves the conduct of research for developing minimum aviation system performance standards (MASPS) for these flight deck display technologies to aid flight crew attitude and energy state awareness similar to that of a virtual day-VMC-like environment. This paper will describe a novel experimental approach to evaluating a flight crew's ability to maintain attitude awareness and to prevent entry into unusual attitudes across several SVS optical flow design considerations. Flight crews were subjected to compound-event scenarios designed to elicit channelized attention and startle/surprise within the crew. These high-fidelity scenarios, designed from real-world events, enable evaluation of the efficacy of SVS at improving flight crew attitude awareness to reduce the occurrence of LOC-I incidents in commercial flight operations.

Ellis, Kyle K. E.↗
NASA NTRS2016

Considerations for the Use of Remote Gaze Tracking to Assess Behavior in Flight Simulators

Complex user interfaces (such as those found in an aircraft cockpit) may be designed from first principles, but inevitably must be evaluated with real users. User gaze data can provide valuable information that can help to interpret other actions that change the state of the system. However, care must be taken to ensure that any conclusions drawn from gaze data are well supported. Through a combination of empirical and simulated data, we identify several considerations and potential pitfalls when measuring gaze behavior in high-fidelity simulators. We show that physical layout, behavioral differences, and noise levels can all substantially alter the quality of fit for algorithms that segment gaze measurements into individual fixations. We provide guidelines to help investigators ensure that conclusions drawn from gaze tracking data are not artifactual consequences of data quality or analysis techniques.

eye tracking↗
NASA NTRS2017

Thermal Considerations for Reducing the Cooldown and Warmup Duration of the James Webb Space Telescope OTIS Cryo-Vacuum Test

The James Webb Space Telescope (JWST), set to launch in 2018, is NASAs next-generation flagship telescope. The Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) contain all of the optical surfaces and instruments to capture and analyze the telescopes infrared targets. The integrated OTE and ISIM are denoted as OTIS, and will be tested as a single unit in a critical thermal-vacuum test in mid-2017 at NASA Johnson Space Centers Chamber A facility. The payload will be evaluated for workmanship and functionality in a 20K simulated flight environment during this thermal-vacuum test. However, the sheer thermal mass of the OTIS payload as well as the restrictive gradient, rate, and contamination-related constraints placed on test components precludes rapid cooldown or warmup to its steady-state cryo-balance condition. Hardware safety considerations precludes injection of helium gas for free molecular heat transfer. Initial thermal analysis predicted that transient radiative cooldown from ambient temperatures, while meeting all limits and constraints, would take 33.3 days; warmup similarly would take 28.4 days. This paper discusses methods used to reduce transition times from the original predictions through modulation of boundary temperatures and environmental conditions. By optimizing helium shroud transition rates and heater usage, as well as rigorously re-examining previously imposed constraints, savings of up to three days on cooldown and up to a week on warmup can be achieved. The efficiencies gained through these methods allow the JWST thermal test team to create faster cooldown and warmup profiles, thus reducing the overall test duration and cost, while keeping all of the required test operations.

Thermal↗