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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Electrostatic protection of the solar power satellite and rectenna. Part 1: Protection of the solar power satellite

Several features of the interactions of the Solar Power Satellite (SPS) with its space environment are examined theoretically. The voltages produced at various surfaces due to space plasmas and the plasma leakage currents through the kapton and sapphire solar cell blankets are calculated. At geosynchronous orbit, this parasitic power loss is only 0.7%, and is easily compensated by oversizing. At low Earth orbit, the power loss is potentially much larger (3%), and anomalous arcing is expected for the EOTV high voltage negative surfaces. Preliminary results of a three dimensional self consistent plasma and electric field computer program are presented, confirming the validity of the predictions made from the one dimensional models. Lastly, magnetic shielding of the satellite is considered to reduce the power drain and to protect the solar cells from energetic electron and plasma ion bombardment. It is concluded that minor modifications can allow the SPS to operate safely and efficiently in its space environment. Subsequent design changes will substantially alter the basic conclusions.

Source record↗
NASA NTRS1980

Multiple-Time-Scale Concepts in Turbulent Transport Modeling

Progress in developing a turbulence closure employing two or more independently calculated time scales with which to characterize the rates of progress of different turbulent interactions is reported. The energy containing part of the spectrum is divided into two regions which respond at different rates and in different ways to changes in the environment. The scheme may be regarded as providing an intermediate level of approximation between the relatively simple, but fallible, single-point closures and the vastly more elaborate two-point closures which have so far been applied only to simulating homogeneous flows. The proposed approach requires only slightly more computational effort than single-scale schemes. Computational results are reported for several thin shear flows which show striking improvement in the level of agreement with experiment over that obtained with models employing only one time scale.

Hanjalic, K.↗
NASA NTRS1980

Aerospace in the future

National research and technology trends are introduced in the environment of accelerating change. NASA and the federal budget are discussed. The U.S. energy dependence on foreign oil, the increasing oil costs, and the U.S. petroleum use by class are presented. The $10 billion aerospace industry positive contribution to the U.S. balance of trade of 1979 is given as an indicator of the positive contribution of NASA in research to industry. The research work of the NASA Lewis Research Center in the areas of space, aeronautics, and energy is discussed as a team effort of government, the areas of space, aeronautics, and energy is discussed as a team effort of government, industry, universities, and business to maintain U.S. world leadership in advanced technology.

Mccarthy, J. F., Jr.↗
NASA NTRS1983

Spectral chemistry of green glass-bearing 15426 regolith

The detection of appreciable concentrations of ferric iron in a synthetic green glass equilibrated at an oxygen fugacity of 10 to the -11th atm prompted a Moessbauer spectral study of pristine emerald-green glass spherules carefully handpicked from regolith sample 15426. No Fe(3+) ions were detected in this lunar sample or in a synthetic green glass simulant equilibrated at fO2 = 10 to the -14th atm, suggesting that the green glass clods in rock 15426 formed under conditions of correspondingly low oxygen fugacities. The Moessbauer spectra indicated the presence of olivine crystallites in the lunar emerald green glass spherules. Measurements of homogeneous and partially devitrified synthetic silicate glasses revealed that significant changes of coordination environment about Fe(2+) ions in the glass structure occur during crystallization of olivine crystals from the melt.

Burns, R. G.↗
NASA NTRS1984

Aerothermodynamic heating analysis of aerobraking and aeromaneuvering orbital-transfer vehicles

The thermal-protection requirements of two aeroassisted orbital-transfer vehicles (AOTVs) are analyzed for return missions between the geosynchronous and Shuttle orbits. One of the designs is a specialized version of a previously proposed generic aerobraking vehicle that is capable of only delivery-type operations. The other is a high-lift aeromaneuvering vehicle that is optimized for low-earth orbit sortie missions involving large, multiple plane-inclination changes. The aerothermal environment of the aerobraking vehicle is analyzed using state-of-the-art methods for nonequilibrium-radiative and convective heating that incorporate refinements unique to the configuration. The heating analysis of the aeromaneuvering vehicle required the development of a flow-field model for rarefied-hypersonic flow over a lifting surface at incidence. The predicted aerothermodynamic heating characteristics for both vehicles are correlated with thermal-control requirements and flight performance capabilities for the specified mission guidelines. The results help identify technical issues related to the development of future operational systems.

Davies, C. B.↗
NASA NTRS1985

Geographic variation in the relationships of temperature, salinity or sigma sub t versus plant nutrient concentrations in the world ocean

A NODC data set representing all regions of the world ocean was analyzed for temperature and sigma-t relationships with nitrate, phosphate or silicic acid. Six cubic regressions were for each ten degree square of latitude and longitude containing adequate data. World maps display the locations that allow the prediction of plant nutrient concentrations from temperature or sigma-t. Geographic coverage improves along the sequence: nitrate, phosphate, and silicic acid and is better for sigma-t than for temperature. Contour maps of the approximate temperature of sigma-t at which these nitrients are no longer measurable in a parcel of water are generated, based on a percentile analysis of the temperature or sigma-t at which less than a selected amount of plant nutrient occurs. Results are stored on magnetic tape in tabular form. The global potential to predict plant nutrient concentrations from remotely sensed temperature of sigma-t and to emphasize the latitudinally and longitudinally changing phytoplankton growth environment in present and past oceans is demonstrated.

Kamykowski, D.↗
NASA NTRS1983

Shuttle imaging radar-A (SIR-A) data analysis

The utility of shuttle imaging radar (SIR-A) data was evaluated in several geological and environmental contexts. For the Ozark Plateau of southern Missouri, SIR-A data were of little use in mapping structural features, because of generally uniform returns. For western Illinois, little was to be gained in terms of identifying land use categories by examining differences between overlapping passes. For southern Australia (Koonamore Station), information ion vegetation types that was not obtainable from LANDSAT MSS data alone was obtained. Specifically, high SIR-A returns in the Australian site were found to correlate with locations where shrubs increase surface roughness appreciably. The Australian study site results demonstrate the synergy of acquiring spectral reflectance and radar data over the same location and time. Such data are especially important in that region, since grazing animals have substantially altered and are continuing to alter the distribution of shrublands, grasslands, and soil exposures. Periodic, synoptic acquisition of MSS and SAR data would be of use in monitoring the dynamics of land-cover change in this environment.

Arvidson, R. E.↗
NASA NTRS1986

Application of photosynthetic N2-fixing cyanobacteria to the CELSS program

Commercially available air lift fermentors were used to simultaneously monitor biomass production, N2-fixation, photosynthesis, respiration, and sensitivity to oxidative damage during growth under various nutritional and light regimes, to establish a data base for the integration of these organisms into a Closed Ecological Life Support System (CELSS) program. Certain cyanobacterial species have the unique ability to reduce atmospheric N2 to organic nitrogen. These organisms combine the ease of cultivation characteristics of prokaryotes with the fully developed photosynthetic apparatus of higher plants. This, along with their ability to adapt to changes in their environment by modulation of certain biochemical pathways, make them attractive candidates for incorporation into the CELSS program.

Packer, L.↗
NASA NTRS1986

Infusion extractor

This invention relates to an apparatus and method of removing desirable constituents from an infusible material by infusion extraction. A piston operating in a first chamber draws a solvent into the first chamber where it may be heated, and then moves the heated solvent into a second chamber containing the infusible material, where infusion extraction takes place. The piston then moves the solvent containing the extract through a filter into the first chamber, leaving the extraction residue in the second chamber. The method is applicable to operation in low or micro-gravity environments.

Chang-Diaz, Franklin R.↗
NASA NTRS1987

Intelligent signal analysis and recognition

Progress in the research and development of self-organizing database system that can support the identification and characterization of signals in an RF environment is described. As the radio frequency spectrum becomes more crowded, there are a number of situations that require a characterization of the RF environment. This database system is designed to be practical in applications where communications and other instruments encounter a time varying and complex RF environment. The primary application of this system is the guidance and control of NASA's SETI Microwave Observing Project. Other possible applications include selection of telemety bands for communication with spacecraft, and the scheduling of antenna for radio astronomy are two examples where characterization of the RF environment is required. In these applications, the RF environment is constantly changing, and even experienced operators cannot quickly identify the multitude of signals that can be encountered. Some of these signals are repetitive, others appear to occur sporadically.

Levinson, Robert↗
NASA NTRS1987

Fed-batch control based upon the measurement of intracellular NADH

A series of experiments demonstrating that on-line measurements of intracellular NADH by culture fluorescence can be used to monitor and control the fermentation process are described. A distinct advantage of intercellular NADH measurements over other monitoring techniques such as pH and dissolved oxygen is that it directly measures real time events occurring within the cell rather than changes in the environment. When coupled with other measurement parameters, it can provide a finer degree of sophistication in process control.

Armiger, W. B.↗
NASA NTRS1987

The impact of launch vehicle constraints on U.S. Space Station design and operations

The assembly of the Space Station is examined in terms of user and operational requirements. The Space Shuttle/Space Station interface is analyzed. The effect of the changing space transportation environment on the Space Station assembly requirements and the lift capabilities of the Shuttle are investigated. Consideration is given to crew replacement and the Shuttle launch rate; the use of the advanced solid rocket motor to increase the lifting capability of the Shuttle to 52,000 lbs; and the use of ELVs for launching modules of the Space Station.

Ambrus, Judith H.↗
NASA NTRS1989

A situated reasoning architecture for space-based repair and replace tasks

Space-based robots need low level control for collision detection and avoidance, short-term load management, fine-grained motion, and other physical tasks. In addition, higher level control is required to focus strategic decision making as missions are assigned and carried out. Reasoning and control must be responsive to ongoing changes in the environment. Research aimed at bridging the gap between high level artificial intelligence (AI) planning techniques and task-level robot programming for telerobotic systems is described. Situated reasoning is incorporated into AI and Robotics systems in order to coordinate a robot's activity within its environment. An integrated system under development in a component maintenance domain is described. It is geared towards replacing worn and/or failed Orbital Replacement Units (ORUs) designed for use aboard NASA's Space Station Freedom based on the collection of components available at a given time. High level control reasons in component space in order to maximize the number operational component-cells over time, while the task-level controls sensors and effectors, detects collisions, and carries out pick and place tasks in physical space. Situated reasoning is used throughout the system to cope with component failures, imperfect information, and unexpected events.

Bloom, Ben↗
NASA NTRS1990

Monitoring and control of spacecraft systems using procedural reasoning

Research concerned with automating the monitoring and control of spacecraft systems is discussed. In particular, the application of SRI's Procedural Reasoning System (PRS) to the handling of malfunctions in the Reaction Control System (RCS) of NASA's Space Shuttle is examined. Unlike traditional monitoring and control systems, PRS is able to reason about and perform complex tasks in a very flexible and robust manner, somewhat in the manner of a human assistant. Using various RCS malfunctions as examples (including sensor faults, leaking components, multiple alarms, and regulator and jet failures), it is shown how PRS manages to combine both goal-directed reasoning and the ability to react rapidly to unanticipated changes in its environment. In conclusion, some important issues in the design of PRS are reviewed and future enhancements are indicated.

Georgeff, Michael P.↗
NASA NTRS1989

Exploiting map plans as resources for action

When plans are used as programs for controlling the action of autonomous or teleoperated robots, their abstract representation can easily obscure a great deal of the critical knowledge that originally led to the planned course of action. An autonomous vehicle experiment is highlighted which illustrates how the information barriers created by abstraction can result in undesirable action. It is then shown how the same task can be performed correctly using plans as a resource for action. As a result of this simple change in outlook, problems requiring opportunistic reaction to unexpected changes in the environment can be solved.

Payton, David↗
NASA NTRS1989

A design strategy for autonomous systems

Some solutions to crucial issues regarding the competent performance of an autonomously operating robot are identified; namely, that of handling multiple and variable data sources containing overlapping information and maintaining coherent operation while responding adequately to changes in the environment. Support for the ideas developed for the construction of such behavior are extracted from speculations in the study of cognitive psychology, an understanding of the behavior of controlled mechanisms, and the development of behavior-based robots in a few robot research laboratories. The validity of these ideas is supported by some simple simulation experiments in the field of mobile robot navigation and guidance.

Forster, Pete↗
NASA NTRS1989

Planetary protection and back contamination control for a Mars rover sample return mission

A commitment to avoid the harmful contamination of outer space and avoid adverse changes in the environment of the earth has been long reflected in NASA's Planetary Protection policy. Working under guidelines developed by the Committee on Space Research (COSPAR), NASA has implemented the policy in an interactive process that has included the recommendations of the U.S. National Academy of Sciences. Measures taken to prevent the contamination of earth during the Apollo missions were perhaps the most visible manifestations of this policy, and provided numerous lessons for future sample return opportunities. This paper presents the current status of planetary protection policy within NASA, and a prospectus on how planetary protection issues might be addressed in relation to a Mars Rover Sample Return mission.

Rummel, John D.↗
NASA NTRS1990

Mission to Planet Earth

To preserve the earth, it is necessary to understand the tremendously complex interactions of the atmosphere, oceans, land, and man's activities deeply enough to construct models that can predict the consequences of our actions and help us make sound environmental, energy, agriculture, and economic decisions. Mission to Planet Earth is NASA's suggested share and the centerpiece of the U.S. contribution to understanding the environment, the Global Change Research Program. The first major element of the mission would be the Earth Observing System, which would give the simultaneous, comprehensive, long-term earth coverage lacking previously. NASA's Geosynchronous Earth Observatory with two additional similar spacecraft would be orbited by the U.S., plus one each by Japan and the European Space Agency. These would be the first geostationary satellites to span all the disciplines of the earth sciences. A number of diverse data gathering payloads are also planned to be carried aboard the Polar Orbiting Platform. Making possible the long, continuous observations planned and coping with the torrent of data acquired will require technical gains across a wide front. Finally, how all this data is consolidated and disseminated by the EOS Data and Information System is discussed.

Tilford, Shelby G.↗