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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

The Extended Mission Rover (EMR)

A key component in ensuring America's status as a leader in the global community is its active pursuit of space exploration. On the twentieth anniversary of Apollo 11, President George Bush challenged the nation to place a man on the moon permanently and to conduct human exploration of Mars in the 21st century. The students of the FAMU/FSU College of Engineering hope to make a significant contribution to this challenge, America's Space Exploration Initiative (SEI), with their participation in the NASA/USRA Advanced Design Program. The project selected by the 1991/1992 Aerospace Design group is the design of an Extended Mission Rover (EMR) for use on the lunar surface. This vehicle will serve as a mobile base to provide future astronauts with a 'shirt-sleeve' living and working environment. Some of the proposed missions are planetary surface exploration, construction and maintenance, hardware setup, and in situ resource experimentation. This vehicle will be put into use in the 2010-2030 time frame.

Shields, W.↗
NASA NTRS1994

Development of braided rope engine seals

In this study, after reviewing current seal design concepts, the potential of textile structures for seal design is examined from the material, structural, and fabrication points of view. Braided structures are identified as potential candidates for hypersonic seal structures because of their conformability and design flexibility. A large family of braided structures using 2-D and 3-D architecture can be designed using well established methods to produce a wide range of braiding yarn orientation for wear resistance as well as seal porosity control. As a first demonstration of the approach, 2-D braided fiberglass seals were fabricated according to a factorial design experiment by varying braiding angles, fractional longitudinal fibers, and preload pressure levels. Factorial diagrams and response surfaces were constructed to elucidate the inter-relationship of the braiding parameters as well as the effect of preload pressures on leakage resistance of the seal. It was found that seal resistance is a strong function of fractional longitudinal fiber content. As braiding angle increases, seal leakage resistance increases, especially at high preload pressures and in seals having high proportion of longitudinal fibers.

Ko, Frank K.↗
NASA NTRS1998

User Directed Tools for Exploiting Expert Knowledge in an Immersive Segmentation and Visualization Environment

Volumetric data sets have become common in medicine and many sciences through technologies such as computed x-ray tomography (CT), magnetic resonance (MR), positron emission tomography (PET), confocal microscopy and 3D ultrasound. When presented with 2D images humans immediately and unconsciously begin a visual analysis of the scene. The viewer surveys the scene identifying significant landmarks and building an internal mental model of presented information. The identification of features is strongly influenced by the viewers expectations based upon their expert knowledge of what the image should contain. While not a conscious activity, the viewer makes a series of choices about how to interpret the scene. These choices occur in parallel with viewing the scene and effectively change the way the viewer sees the image. It is this interaction of viewing and choice which is the basis of many familiar visual illusions. This is especially important in the interpretation of medical images where it is the expert knowledge of the radiologist which interprets the image. For 3D data sets this interaction of view and choice is frustrated because choices must precede the visualization of the data set. It is not possible to visualize the data set with out making some initial choices which determine how the volume of data is presented to the eye. These choices include, view point orientation, region identification, color and opacity assignments. Further compounding the problem is the fact that these visualization choices are defined in terms of computer graphics as opposed to language of the experts knowledge. The long term goal of this project is to develop an environment where the user can interact with volumetric data sets using tools which promote the utilization of expert knowledge by incorporating visualization and choice into a tight computational loop. The tools will support activities involving the segmentation of structures, construction of surface meshes and local filtering of the data set. To conform to this environment tools should have several key attributes. First, they should be only rely on computations over a local neighborhood of the probe position. Second, they should operate iteratively over time converging towards a limit behavior. Third, they should adapt to user input modifying they operational parameters with time.

Senger, Steven O.↗
NASA NTRS1999

Energy Minimization of Molecular Features Observed on the (110) Face of Lysozyme Crystals

Molecular dynamics and energy minimization have been carried out using the program XPLOR to check the plausibility of a model lysozyme crystal surface. The molecular features of the (110) face of lysozyme were observed using atomic force microscopy (AFM). A model of the crystal surface was constructed using the PDB file 193L, and was used to simulate an AFM image. Molecule translations, van der Waals radii, and assumed AFM tip shape were adjusted to maximize the correlation coefficient between the experimental and simulated images. The highest degree of 0 correlation (0.92) was obtained with the molecules displaced over 6 A from their positions within the bulk of the crystal. The quality of this starting model, the extent of energy minimization, and the correlation coefficient between the final model and the experimental data will be discussed.

Perozzo, Mary A.↗
NASA NTRS2004

Human-Induced Climate Variations Linked to Urbanization: From Observations to Modeling

The goal of this session is to bring together scientists from interdisciplinary backgrounds to discuss the data, scientific approaches and recent results focusing on the impact of urbanization on the climate. The discussion will highlight current observational and modeling capabilities being employed for investigating the urban environment and its linkage to the change in the Earth's climate system. The goal of the session is to identify our current stand and the future direction on the topic. Urbanization is one of the extreme cases of land use change. Most of population of the world has moved to urban areas. By 1995, more than 70% of population of North America and Europe were living in cities. By 2025, the United Nations estimates that 60% of the worlds population will live in cities. Although currently only 1.2% of the land is urban, better understanding of how the atmosphere-ocean-land-biosphere components interact as a coupled system and the influence of human activities on this system is critical. Our understanding of urbanization effect is incomplete, partly because human activities induce new changes on climate in addition to the original natural variations, and partly because previously few data available for study urban effect globally. Urban construction changes surface roughness, albedo, heat capacity and vegetation coverage. Traffic and industry increase atmospheric aerosol. It is suggested that urbanization may modify rainfall processes through aerosol-cloud interactions or dynamic feedbacks. Because urbanization effect on climate is determined by many factors including land cover, the city's microscale features, population density, and human lifestyle patterns, it is necessary to study urban areas over globe.

Shepherd, J. Marshall↗
NASA NTRS2021

The Role of Tactile Cueing in Multimodal Displays: Application in Complex Task Environments for Space Exploration

This paper reviews the potential role of tactile cueing in multimodal displays that will need to be developed to enable Extravehicular Activity (EVA) and telerobotic exploration for both Moon and Mars missions. Specific missions to be accomplished during EVA surface and space operations will include construction and assembly, surface and geologic exploration, and excavation for protective shelter from radiation and significant solar particle events. EVA crews have limited time, resources, mobility, visibility and dexterity, and activities take place in a perceptually impoverished environment. Limitations include a loss of spatial reference frame leading to spatial disorientation, a loss of information normally provided by the auditory and somato-sensory systems, and a restricted field of view. In addition, in non-surface operations crew must be able to navigate and operate in a fully six degree of freedom (DoF) environment. Fatigue resulting from suited EVA tasks will also critically affect performance and safety. In order to mitigate these factors, it is important that crews be well trained prior to executing actual missions. There is a critical need to design multimodal interfaces to optimize performance under these conditions for both training and actual operations. Because of the high level of complexity of the EVA environment on the one hand, and the “sensory restrictions” on the other, it makes sense to envisage enhancements to the astronauts’ visual environment. Such an enriched environment may include virtual auditory as well as tactile inputs.

multimodal displays↗
NASA NTRS2021

On-orbit Servicing, Assembly, and Manufacturing (OSAM) State of Play, 2021 Edition

This document compiles and organizes the current state of OSAM missions, capabilities, and developments. Understanding where the set of capabilities currently stand will help mission designers incorporate OSAM technologies into their concepts, create the starting point for technology development plans and roadmaps, and provide technologists a survey of the field they are developing. The authors recognize that this capability is broad and that they are unlikely to have captured everything that has been or is being done in the area on the first attempt. As a result, a new version of the OSAM State of Play will be released periodically (perhaps annually).

OSAM↗
NASA NTRS2023

Tall Lunar Tower (TLT) Powering Exploration at the Moon's South Pole

Animation of a conceptual Lunar mission for the Tall Lunar Tower (TLT) robotic in-space assembly system. The landing, deployment, and operation of the tower assembly system is shown. A successful tower assembly and solar power payload is depicted at the lunar south pole. The video is intended to convey how an engineering development unit (EDU) demonstrated at NASA Langley Research Center may look when operated on the Lunar surface. The EDU models are shown in place of flight hardware. The animation was produced by the Advanced Concepts Laboratory with models provided by the TLT team.

Tall Lunar Tower↗
NASA NTRSDate not supplied

Geologic Maps for Civil Engineering and Infrastructure Planning

The Artemis Program mandate for sustainable, long-term presence on the Moon requires learning to "Live Off the Land". Geologic maps enable a paradigm shift to model the development and scaling of infrastructure for robotic and human exploration inside a bounded system on the lunar surface. Relying on geologic maps produced from orbital data and robotic precursor missions, in-situ resource utilization (ISRU) will be required to produce infrastructure, building materials and consumables. The ISRU value chain must be mapped to identify linkages of resources, producers, processes and equipment capabilities for transforming excavated regolith into usable feedstocks. Coordination will be required to balance supply and demand across the whole system of lunar infrastructure and operations, at each stage of development.

Geologic Mapping↗
NASA NTRS1992

Martian surface simulations

Current scenarios for a Mars landing involve the extensive analysis of the surface near the landing site. Pinpoint landing, for example, requires a detailed mapping of the area from orbit for landmark identification and landing site selection, and the use by the lander of its own imaging data to recognize these landmarks and to guide itself safely to the surface. Hazard avoidance requires sufficient orbital imaging to ensure that safe landing sites exist, with the lander using its sensory data to find one of them. Once on the surface, a rover must be able to avoid or surmount obstacles, travel across surfaces with varying compositions and slopes, and navigate to a desired destination. Computer simulated Martian surfaces are being constructed to aid in the development of these exploration technologies. These surface simulations attempt to mimic the specific geologic episodes that built the surface, such as cratering, lava flows, and aeolian activity. Each episode takes a preexisting surface as a starting point, alters it in some way, and stores the new surface for further processing. This modular construction makes it possible for new processes to be included without altering existing software.

Gaskell, R. W.↗
NASA NTRS1999

Sensitivity of the Tropical Pacific Ocean to Precipitation Induced Freshwater Flux

We have performed a series of experiments using an ocean model to study the sensitivity of tropical Pacific Ocean to variations in precipitation induced freshwater fluxes. Variations in these fluxes arise from natural causes on all time scales. In addition, estimates of these fluxes are uncertain because of differences among measurement techniques. The model used is a quasi-isopycnal model, covering the Pacific from 40 S to 40 N. The surface forcing is constructed from observed wind stress, evaporation, precipitation, and surface temperature (SST) fields. The heat flux is produced with an iterative technique so as to maintain the model close to the observed climatology, but with only a weak damping to that climatology. Climatological estimates of evaporation are combined with various estimates of precipitation to determine the net surface freshwater flux. Results indicate that increased freshwater input decreases salinity as expected, but increases temperatures in the upper ocean. Using the freshwater flux estimated from the Microwave Sounding Unit leads to a warming of up to 0.6 C in the western Pacific over a case with zero net freshwater flux. SST is sensitive to the discrepancies among different precipitation observations, with root-mean-square differences in SST on the order of 0.2-0.3 C. The change in SST is more pronounced in the eastern Pacific, with differences of over 1 C found among the various precipitation products. Interannual variation in precipitation during El Nino events leads to increased warming. During the winter of 1982-83, freshwater flux accounts for about 0.4 C (approximately 10-15% of the maximum warming) of the surface warming in the central-eastern Pacific. Thus, the error of SST caused by the discrepancies in precipitation products is more than half of the SST anomaly produced by the interannual variability of observed precipitation. Further experiments, in which freshwater flux anomalies are imposed in the western, central, and eastern Pacific, show that the influence of net freshwater flux is also spatially dependent. The imposition of freshwater flux in the far western Pacific leads to a trapping of salinity anomaly to the surface layers near the equator. An identical flux imposed in the central Pacific produces deeper and off-equatorial salinity anomalies. The contrast between these two simulations is consistent with other simulations of the western Pacific barrier layer information.

Yang, Song↗
NASA NTRS1998

Molecular Processes in Comets

The research focused on molecular hydrogen and its response to ultraviolet radiation, photoelectron impact excitation and X-ray radiation and on the interpretation of the ultraviolet spectra of the Jupiter dayglow and auroras. A systematic effort was made to obtain reliable rate coefficients for rovibrational energy transfer of H2, particularly in collisions with hydrogen atoms. We carried out elaborate quantum-mechanical calculations of the scattering of H and H2 on what had been characterized as a reliable potential energy surface of the H3 molecular system. These calculations took into account reactive channels and rate coefficients for ortho-para transitions were obtained. Quantal calculations are too complex to be applied to all the possible rovibrational transitions and we turned to a semi-classical method. With it we calculated rate coefficients for transitions, reactive and non-reactive, for all the rovibrational levels. We carried out the calculations for three of the available H3 potential energy surfaces. We discovered an unexpected sensitivity of the rate coefficients for the non-reactive channels to the potential energy surface. This discovery stimulated more thorough investigations of the potential energy surface elsewhere and to the construction of a new surface. We have used it in further semi-classical calculations in work that will shortly be 2 completed and which, together with new quantum-mechanical calculations should comprise a set of reliable rate coefficients that can be used in discussions of H2 on the Jovian planets. We carried out a detailed study of the Jovian ultraviolet dayglow. There has been a long-running argument about the dayglow on Jupiter. There are two sources of excitation: fluorescence and photoelectron impact excitation. It had been argued that a third source "the electron glow" was needed to bring theory and observation into agreement. We believe we have shown conclusively that the third source is unnecessary. We have achieved a close quantitative agreement between the predicted spectrum arising from fluorescence and photoelectrons and the measured spectrum. We also demonstrated a method by which the presence of HD could be established observationary. Similar calculations were carried out of the ultraviolet spectra of the Jovian auroras. We again found close agreement. Indeed, the agreement was so detailed we were able to derive the temperature of the atmosphere. We found, contrary to the standard model of the time, a high temperature between 400 K and 600 K and established the presence of a significant temperature gradient. A large temperature gradient was indeed found by direct sampling with the Jupiter probe.

Dalgarno, A.↗
NASA NTRS1990

Technology and Mars exploration

The currently envisioned technology needs of the Space Exploration Initiative are surveyed. Earth-to-orbit transportation technology requirements are summarized. Space transportation needs regarding aerobraking, space-based engines, autonomous landing, autonomous rendezvous and docking, vehicle structures and cryogenic tankage, artificial gravity, nuclear propulsion, nuclear thermal propulsion, and nuclear electric propulsion. For in-space operations, cryogenic fluid systems, in-space assembly and construction, and vehicle processing and servicing are addressed. For surface operations on the moon and Mars, space nuclear power, resource utilization, planetary rovers, surface solar power, and surface habitats and construction are discussed. Regenerative life support, radiation protection, extravehicle activity, are considered along with factors pertaining to scientific activity in space and information systems and communications.

Mankins, John C.↗
NASA NTRS1989

Manned Mars mission on-orbit operations FTS capabilities assessment

This document presents an overview of the characteristics and capabilities of the flight telerobotic servicer (FTS), under development at GSFC at the time the report was prepared; the project has since been cancelled. The assessment was directed toward developing the FTS to enable assembly and servicing of the Mars vehicle at the space station; facilitate rendezvous, docking, and fluid transfer operations involving the Mars vehicle fuel tank; to perform strip-mining operations on the lunar/martian surfaces; and to construct a three-story shelter on the martian surface. The report considers the FTS' mechanical, electrical, thermal, and operational subsystems, as well as its proposed manipulator capabilities.

Gallo, Frank G.↗