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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 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Non-LTE calculation of HCL earthlimb emission and implication for detection of HCl in the atmosphere

Calculation results are presented for the contribution of the non-Local Thermodynamic Equilibrium process of resonant scattering of sunlight in the 1-0 band of HCl to the earthlimb radiance, for the case of tangent altitudes from 20 to 90 km. It is established that the mechanism in question is a significant contributor to radiance at altitudes as low as 20 km, and that it becomes greater than the Local Thermodynamic Equilibrium contribution above 40 km. Attention is given to the prospects for detection of HCl at altitudes approaching 80 km, by means of the Cryogenic Limb Array Etalon Spectrometer scheduled for deployment by the NASA Upper Atmospheric Research Satellite.

Kumer, J. B.↗
NASA NTRS1981

Field failure mechanisms for photovoltaic modules

Beginning in 1976, Department of Energy field centers have installed and monitored a number of field tests and application experiments using current state-of-the-art photovoltaic modules. On-site observations of module physical and electrical degradation, together with in-depth laboratory analysis of failed modules, permits an overall assessment of the nature and causes of early field failures. Data on failure rates are presented, and key failure mechanisms are analyzed with respect to origin, effect, and prospects for correction. It is concluded that all failure modes identified to date are avoidable or controllable through sound design and production practices.

Dumas, L. N.↗
NASA NTRS1982

Space science payloads for Shuttle

This paper presents a sampling of space science missions currently planned or under study at the Jet Propulsion Laboratory. Early use of the Shuttle for launching planetary exploration missions will not differ very much in principle from expendable launch vehicles. Future concepts which make use of the unique characteristics of the Shuttle in conjunction with other new technology open some truly fascinating prospects. Shuttle has other roles in space science as well, both for deep space and earth-directed observations. A variety of payload concepts, ranging from highly conventional to 'far-out', are under study. Increasing experience with Shuttle operations will broaden the spectrum of possibilities.

French, J. R.↗
NASA NTRS1982

Spectrum of the microwave background radiation

A review is given of the present status of measurements of the spectrum of the microwave background. Factors that limit experimental accuracy are discussed with particular reference to high-frequency measurements. A selection of the available measurements yields a data set that is reasonably consistent with the black-body spectrum for a temperature of 2.9 K. A simple statistical analysis suggests either that there are errors in the data set, or that deviations from a black-body spectrum exist. The difficulties inherent in properly averaging the results from different observers are described. Prospects for improved measurements are summarized.

Richards, P. L.↗
NASA NTRS1984

Dual-Rate Transmission Reduces Weather Effects

Scheme ensures maximum data received on average. Dual-rate scheme for maximizing data returned during spacecraft mission, adaptable, as is or with modifications, to high-frequency terrestrial data transmission. Data rate fixed in advance at minimum value guarantees reasonable prospect of success during bad weather. Dualrate strategy yields net data rate 2.5 times best achievable with single transmission rate.

Posner, E. C.↗
NASA NTRS1982

Research in space commercialization, technology transfer, and communications

Research and internship programs in technology transfer, space commercialization, and information and communications policy are described. The intern's activities are reviewed. On-campus research involved work on the costs of conventional telephone technology in rural areas, an investigation of the lag between the start of a research and development project and the development of new technology, using NASA patent and patent waiver data, studies of the financial impact and economic prospects of a space operation center, a study of the accuracy of expert forecasts of uncertain quantities and a report on frequency coordination in the fixed and fixed satellite services at 4 and 6 GHz.

Source record↗
NASA NTRS1982

Development of the operational program for satellite meteorology

The geostationary and polar satellites comprising the current operational system are discussed. The data acquisition capabilities of both satellite types and their complementary functions are reviewed. The advanced very high resolution radiometer on the TIROS N satellites is particularly addressed along with the imaging and atmospheric sounding instrumentation aboard the GOES satellites. The dissemination of the satellite data to the prospective users is also discussed.

Johnson, D. S.↗
NASA NTRS1983

GaAs solar cells for concentrator systems in space

Cells for operation in space up to more than 100 suns were made, and an AMO efficiency of 21% at 100 suns with these cells was obtained. The increased efficiency resulted not only from the higher open circuit voltage associated with the higher light intensity (higher short circuit current); it also benefitted from the increase in fill factor caused by the lower relative contribution of the generation recombination current to the forward bias current when the cell's operating current density is increased. The experimental cells exhibited an AMO efficiency close to 16% at 200 C. The prospect of exploiting this capability for the continuous annealing of radiation damage or for high temperature missions (e.g., near Sun missions) remains therefore open. Space systems with concentration ratios on the order of 100 suns are presently under development. The tradeoff between increased concentration ratio and increased loss due to the cell's series resistance remains attractive even for space applications at a solar concentrator ratio of 100 suns. In the design of contact configuration with low enough series resistance for such solar concentration ratios, the shallow junction depth needed for good radiation hardness and the thin AlGaAs layer thickness needed to avoid excessive optical absorption losses have to be retained.

Loo, R. Y.↗
NASA NTRS1982

Sun, Earth and man: The need to know. The quest for knowledge of Sun-Earth relations

Solar physics and the effects of emanations from the Sun on communications and Earth's weather and climate are discussed. Scientific interest in the solar system from the old Stone Age to the present is reviewed with particular emphasis on the objectives sought and information obtained by Explorer satellites, Pioneer satellites, Skylab, Helios, ISEE, the solar maximum mission, and the Dynamics Explorer. The goals of missions planned for the 1980's are discussed including those using space shuttle, Spacelab, the Solar Mesosphere Explorer, the solar optical telescope, the upper atmosphere research satellite, and the solar probe. The objectives of the international solar polar mission and of the Origin of Plasma in Earth's Neighborhood mission are also delineated. Other missions being considered are reviewed and the prospect of taming the fusion process to provide clean, harmless electrical energy like that obtained from the Sun is entertained.

Stafford, E. P.↗
NASA NTRS1982

A search for equilibrium states

An efficient search algorithm is described for the location of equilibrium states in a search set of states which differ from one another only by the choice of pure phases. The algorithm has three important characteristics: (1) it ignores states which have little prospect for being an improved approximation to the true equilibrium state; (2) it avoids states which lead to singular iteration equations; (3) it furnishes a search history which can provide clues to alternative search paths.

Zeleznik, F. J.↗
NASA NTRS1983

Analysis and critical assessment of the current and near future plans of the Brazilian satellite applications program and its role in the global space program

Brazilian programs using satellites for remote sensing, meteorology and communications are analyzed including their current status and near future plans. The experience gained and available information are used to critically discuss some aspects of great importance for the existing and prospective user countries.

Parada, N. D. J.↗
NASA NTRS1983

Performance interface document for users of Tracking and Data Relay Satellite System (TDRSS) electromechanically steered antenna systems (EMSAS)

Satellites that use the NASA Tracking and Data Relay Satellite System (TDRSS) require antennas that are crucial for performing and achieving reliable TDRSS link performance at the desired data rate. Technical guidelines are presented to assist the prospective TDRSS medium-and high-data rate user in selecting and procuring a viable, steerable high-gain antenna system. Topics addressed include the antenna gain/transmitter power/data rate relationship; Earth power flux-density limitations; electromechanical requirements dictated by the small beam widths, desired angular coverage, and minimal torque disturbance to the spacecraft; weight and moment considerations; mechanical, electrical and thermal interfaces; design lifetime failure modes; and handling and storage. Proven designs are cited and space-qualified assemblies and components are identified.

Hockensmith, R.↗
NASA NTRS1982

Geographic Information System in Bolivia: a Case Study for Latin America

Bolivia's Geological Service is concluding a successful project designed to give the Department of Oruro the capability to evaluate its natural resources using data generated by three United States satellites. A permanent integrated geographic information system was created for preparing base maps of soil characteristics, land use, geomorphology, geology, water resources and hydrology. The information compiled through the project was stored on magnetic disks and tapes to permit periodic updating, retrieval of data on specific aspects of development projects, and obtaining various data mixes to analyze aspects of prospective development projects. This is the first digital information system developed in Latin America.

Adrien, P. M.↗
NASA NTRS1982

DOE/NASA Automotive Stirling Engine Project overview '83

An overview of the DOE/NASA Automotive Stirling Engine Project is presented. The background and objectives of the project are reviewed. Project activities are described and technical progress and status are presented and assessed. Prospects for achieving the objective 30% fuel economy improvement are considered good. The key remaining technology issues are primarily related to life, reliability and cost, such as piston rod seals, and low cost heat exchanges.

Beremand, D. G.↗
NASA NTRS1982

LANDSAT imagery: Description of products available from the CSIR Satellite Remote Sensing Centre

An overview of the LANDSAT system is provided along with information to assist prospective users in establishing whether imagery for their areas of interest is available and how to obtain such imagery. Spectral bands, spatial resolution, and digital data are explained as well as worldwide reference system indexing and the identification number assigned to images. The sizes and scales of standard black and white imagery and of false color composite imagery are listed. The format is given for computer compatible tapes and standard enhanced imagery is described. Other information available to users include LANDSAT index maps, catalogs of available imagery, a schedule of overpass dates, and a list of product prices.

Source record↗
NASA NTRS1982

Facilities for US radioastronomy

An overview of the radio-astronomy field is given, and prospects ready for construction at NASA are presented. A very-long-baseline array consisting of ten 25 m antennas, with a limiting wavelength of 7 mm and an angular resolution at that wavelength of 2 x 10 to the 4th arcsec is discussed. Eighty percent of the phase information will be obtained by closure around the 36 independent triangles, and high quality aperture-synthesis maps will be produced at all wavelengths. The 25 m telescope will be capable of several applications including the discovery of new molecules in our galaxy (in particular, the envelope of the evolved carbon star IRC + 10216), the detection of CO to distances of perhaps 100 million light years, and the understanding of the events which occur as stars are formed from molecular clouds, and as energy is fed back into the molecular gas by new stars. The submillimeter-wave telescope contains the last atmospheric radio windows where astronomical observations can be made from the earth's surface. The need for funding is stressed.

Thaddeus, P.↗