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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 91 records · Page 5
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NASA NTRS1977

Feasibility analysis of gravitational experiments in space

Experiments on gravitation and general relativity suggested by different workers in the past ten or more years are reviewed, their feasibility examined, and the advantages of performing them in space were studied. The experiments include: (1) the gyro relativity experiment; (2) experiments to test the equivalence of gravitational and inertial mass; (3) an experiment to look for nongeodesic motion of spinning bodies in orbit around the earth; (4) experiments to look for changes of the gravitational constant G with time; (5) a variety of suggestions; laboratory tests of experimental gravity; and (6) gravitational wave experiments.

Everitt, C. W. F.↗
NASA NTRS1979

Interplanetary dust

Progress in the study of interplanetary dust during the past four years is reviewed. Attention is given to determinations of the relative contributions of interstellar dust grains, collisional debris from the asteroid belt and short-period comets to the interplanetary dust cloud. Effects of radiation pressure and collisions on particle dynamics are discussed, noting the discovery of the variation of the orbital parameters of dust particles at 1 AU with size and in situ measurements of dust density between 0.3 and 5 AU by the Helios and Pioneer spacecraft. The interpretation of the zodiacal light as produced by porous absorbing particles 10 to 100 microns in size is noted, and measurements of the Doppler shift, light-producing-particle density, UV spectrum, photometric axis and angular scattering function of the zodiacal light are reported. Results of analyses of lunar rock microcraters as to micrometeoroid density, flux rate, size distribution and composition are indicated and interplanetary dust particles collected from the stratosphere are discussed. Findings concerning the composition of fragile meteoroid types found as cosmic spherules in deep sea sediments are also presented.

Brownlee, D. E.↗
NASA NTRS1979

NASA advanced communications systems analysis

The purpose of the paper is to investigate and study in-depth market and system analysis for improving satellite communications. The analyses fall into two categories: the broad, scoping efforts intended to screen potential candidates and studies to develop viable operational system configurations and identify critical technology elements. To illustrate the approach, the results of 30/20 GHz study efforts which have been under way in the past few years are reviewed in detail.

Ward, J. J.↗
NASA NTRS1980

Satellite solar occultation sounding of the middle atmosphere

This paper discusses the principles, achievements, and prospects for satellite solar occultation sounding of the middle atmosphere. Advantages, disadvantages, and spatial and temporal coverage capabilities are described. Progress over the past 15 years is reviewed, and results from a recent satellite aerosol experiment are presented. Questions with regard to Doppler shift, atmospheric refraction, instrument pointing, pressure sensing, and measurement of diurnally active species are addressed. Two experiments now orbiting on the Nimbus-7 and AEM-B satellites, and approved experiments under development for future flights on Spacelab and the Earth Radiation Budget Satellite, are also described. In some cases more than one experiment is scheduled to be flown on the same spacecraft, and the advantages and synergistic effects of these applications are discussed.

Russell, J. M., III↗
NASA NTRS1981

An overview of general aviation propulsion research programs at NASA-Lewis Research Center

This paper presents a brief overview and technical highlights of general aviation (g/a) propulsion research efforts and studies which have been underway at NASA's Lewis Research Center (LeRC) for the past several years. The review covers near-term improvements for current-type piston engines, as well as studies and limited corroborative research on several advanced g/a engine concepts, including diesels, small turboprops and both piston and rotary stratified-charge engines. Also described is basic combustion research, cycle modeling and diagnostic instrumentation work that will be required to make the new engines a reality. The discussion emphasizes the most recently-completed studies and the basic underlying research work, which have not been reported previously.

Willis, E. A.↗
NASA NTRS1980

Solar particle fluxes and the ancient sun

The implications of the statistical data on solar flare particle fluxes, for the present and the ancient sun, considering modern data from the past two solar cycles, C-14 data from the past 7000 years, and Al-26 and Mn-53 data in lunar samples for the last 10-million years are reviewed. All of these records suggest that there is a maximum proton fluence (greater than 10 MeV) from a solar flare on the order of 10 to the 10th p/sq cm, above which the size-frequency distribution steepens sharply. From this it is extremely unlikely that energetic particles from solar flares could have contributed to extinction catastrophes in the fossil record.

Lingenfelter, R. E.↗
NASA NTRS1981

Evolutionary variations of solar luminosity

Theoretical arguments for a 30% increase in the solar luminosity over the past 4.7 billion years are reviewed. A scaling argument shows that this increase can be predicted without detailed numerical calculations. The magnitude of the increase is independent of nuclear reaction rates, as long as conversion of hydrogen to helium provides the basic energy source of the Sun. The effect of the solar luminosity increase on the terrestrial climate is briefly considered. It appears unlikely that an enhanced greenhouse effect, due to reduced gases (NH3, CH4), can account for the long-term paleoclimatic trends.

Endal, A. S.↗
NASA NTRS1982

Evolutionary variations of solar luminosity

The Theoretical arguments for a 30% increase in the solar luminosity over the past 4.7 billion years are reviewed. A scaling argument shows that this increase can be predicted without detailed numerical calculations. The magnitude of the increase is independent of nuclear reaction rates, as long as conversion of hydrogen to helium provides the basic energy source of the Sun. The effect of the solar luminosity increase on the terrestrial climate is briefly considered. It appears unlikely that an enhanced greenhouse effect, due to reduced gases (NH3, CH4), can account for the long-term paleoclimatic trends.

Endal, A. S.↗
NASA NTRS1981

Overview: Western Regional applications Program (WRAP) status

Interactions with all 14 of the states in the Western Region over the past three years are reviewed from NASA's perspective. Outreach and training programs using the M mobile analysis and training extension van, the University Program, classes at the Ames Center, demonstration tests with state agencies, and surveying the needs of local governments are highlighted. Planned activities, the continuance of ASVT's, and the impact of the budget cuts on NASA'S technology program are also considered.

Norman, S. M.↗
NASA NTRS1981

Effects of auroral-particle anisotropies and mirror forces on high-latitude electric fields

It is noted that, for most of the mechanisms for the strong electric fields that characterize the narrow regions in which there is acceleration and precipitation of ring current and/or plasma-sheet plasma, certain effects must be taken into account in simulations of auroral electric fields. The effects are those of auroral particle anisotropy, of mirror forces due to the inhomogeneous geomagnetic field, of auroral electron backscatter by the atmosphere, and of electron trapping by the combination of magnetic mirroring and electrostatic forces. What is more, the effects of the very strong perpendicular electric field must also be taken into account in a kinetic description of the Poisson equation in order to achieve a unified theory of the auroral electrostatic structure. Progress in these areas during the past few years is reviewed. It is shown that particle anisotropies and mirror forces can account for some basic electrostatic features of the quiet arc, while additional effects may be occurring in strong events in which the parallel potential drop is more than about 10 kV.

Chiu, Y. T.↗
NASA NTRS1981

Remote sensing education in NASA's technology transfer program

Remote sensing is a principal focus of NASA's technology transfer program activity with major attention to remote sensing education the Regional Program and the University Applications Program. Relevant activities over the past five years are reviewed and perspective on future directions is presented.

Weinstein, R. H.↗
NASA NTRS1984

Pyrotechnic shock: A literature survey of the Linear Shaped Charge (LSC)

Linear shaped charge (LSC) literature for the past 20 years is reviewed. The following topics are discussed: (1) LSC configuration; (2) LSC usage; (3) LSC induced pyroshock; (4) simulated pyrotechnic testing; (5) actual pyrotechnic testing; (6) data collection methods; (7) data analysis techniques; (8) shock reduction methods; and (9) design criteria. Although no new discoveries have been made in LSC research, charge shapes are improved to allow better cutting performance, testing instrumentation is refined, and some new explosives, for use in LSC, are formulated.

Smith, J. L.↗
NASA NTRS1983

Accreting degenerate dwarfs in close binary systems

Advances in the study of cataclysmic variables made during the past few years are reviewed. The classification of cataclysmic binaries and their dynamic properties are summarized. The hard and soft X-ray emission from these objects is discussed, and two alternative accretion geometries for producing this radiation from deep in the potential well of the degenerate dwarf are considered. The ultraviolet and optical spectrum is addressed, including disk emission and contributions from the companion star. Magnetic fields in cataclysmic variables are discussed, and the temporal behavior of these stars is addressed, including periodic modulations associated with orbital motion and rotation as well as flickering and pulsation reflecting the mass transfer process and the dynamics of matter near the surface of the accreting star. The outburst process is considered, including classical novae, recurrent novae, and dwarf novae.

Cordova, F. A.↗
NASA NTRS1985

Some design considerations for a satellite-borne magnetograph

The design criteria for a compact magnetograph that can monitor solar magnetic fields from a free-flying satellite for 5 to 10 years are reviewed. The signal-to-noise ratio that can be obtained with a 10-cm f/10 refractor operated with a Fabry-Perot filter and a solid-state detector array is derived. The telescope measures the longitudinal component of the magnetic field for the entire solar disk in a few minutes at a 20-G threshold and at 3-arcsec resolution. The Fabry-Perot filter has a lithium niobate etalon, which can be tuned electrically and operated at a fixed tilt angle in such a manner that it cancels the solar rotational Doppler shifts in the transmitted spectrum. Principles of operation of various types of polarization modulators are presented, and it is concluded that photoelastic modulators and liquid-crystal devices hold the most promise for use in a satellite-borne magnetograph,

Rust, D. M.↗
NASA NTRS1985

Statement of Aaron Cohen, Director, Research and Engineering, Johnson Space Center and Chairman, Space Station Advanced Technology Advisory Committee, National Aeronautics and Space Administration, before the Subcommittee on Science, Technology, and Space, Committee on Commerce, Science, and Transportation, United States Senate

The activities of NASA's Space Station Advanced Technology Advisory Committee is discussed. Advanced Technology Advisory Committee (ATAC) activities over the last year are reviewed in preparation of the report to Congress on the potential for advancing automation and robotics technology for the space station and for the U.S. economy.

Cohen, A.↗
NASA NTRS1985

Function, form, and technology - The evolution of Space Station in NASA

The history of major Space Station designs over the last twenty-five years is reviewed. The evolution of design concepts is analyzed with respect to the changing functions of Space Stations; and available or anticipated technology capabilities. Emphasis is given to the current NASA Space Station reference configuration, the 'power tower'. Detailed schematic drawings of the different Space Station designs are provided.

Fries, S. D.↗
NASA NTRS1986

Technical progress in silicon sheet growth under DOE/JPL FSA program, 1975-1986

The technical progress made in the Silicon Sheet Growth Program during its 11 years was reviewed. At present, in 1986, only two of the original 9 techniques have survived to the start-up, pilot-plant stage in industry. These two techniques are the edge-defined, film-fed growth (EFG) technique that produces closed shape polygons, and the WEB dendritic technique that produces single ribbons. Both the status and future concerns of the EFG and WEB techniques were discussed.

Kalejs, J. P.↗
NASA NTRS1986

Dynamical evidence for Planet X

The dynamical evidence for a planet beyond the orbit of Neptune is reviewed. Three years of radio tracking data from Pioneer 10 can be fit to the noise level with no evidence for unmodelled acceleration at a level higher than 5 x 10 to the -14th km/sq s. The evidence does not place severe limits on the Planet X model, but does place a firm limit of five earth masses on a hypothetical comet belt just beyond the orbit of Neptune.

Anderson, John D.↗