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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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NASA NTRS1976

Post-Newtonian gravitational radiation from orbiting point masses

General formulas are derived which describe the gravitational radiation at large distances from a system of bodies whose sizes are small compared with their separations. The calculation is carried out through post-Newtonian order within general relativity. More explicit formulas are derived for two-body systems, and detailed results are presented for circular orbits, gravitational bremsstrahlung, and head-on collisions.

Wagoner, R. V.↗
NASA NTRS1975

Work on cardiovascular imaging supported by NASA and Stanford University

A bibliography of 55 works on cardiovascular imaging and related general cardiography is presented for the period ranging from mid-1975 back to 1968. The listing of papers is developed from a NASA library system computer search. The papers are divided by primary subject matter into the following categories: general cardiography including some comparisons of methods (22 papers), angiography (19 papers), echocardiography (11 papers), radioisotopes (1 paper), and magnetocardiography (2 papers).

Source record↗
NASA NTRS1977

Very massive neutron stars in Ni's theory of gravity

It is shown that in Ni's theory of gravity, which is identical to general relativity in the post-Newtonian limit, neutron stars of arbitrarily large mass are possible. This result is independent, within reasonable bounds, of the equation of state of matter at supernuclear densities.

Mikkelsen, D. R.↗
NASA NTRS1977

Post-Newtonian gravitational bremsstrahlung

Formulae and numerical results are presented for the gravitational radiation emitted during a low-deflection encounter between two massive bodies. Results are valid through post-Newtonian order within general relativity. The gravitational waveform, the total luminosity and total emitted energy, the angular distribution of emitted energy, and the frequency spectrum are discussed in detail. A method boosting the accuracy of these quantities to post Newtonian order is also presented. A numerical comparison of results with those of Peters, and of Kovacs and Thorne shows that the post Newtonian method is reliable to better than 0.1 percent at v = 0.1 c, to a few percent at v = 0.35 c, and to 10 to 20 percent at v = 0.5 c.

Turner, M.↗
NASA NTRS1978

Application of DSN spacecraft tracking technology to experimental gravitation

Spacecraft tracking technology of the Deep Space Net (DSN) has been used in the past to measure the general-relativistic increase in round-trip group delay between earth and a spacecraft. As the DSN technology continues to improve, other gravitational experiments will become possible. Two possibilities are discussed in this paper. The first concerns the application of solar-system dynamics to the testing of general relativity. The second involves the detection of VLF gravitational radiation (0.1 to 0.0001 Hz) by means of Doppler tracking of spacecraft.

Anderson, J. D.↗
NASA NTRS1978

Post-Newtonian gravitational bremsstrahlung

Formulas and numerical results for the gravitational radiation emitted during a low-deflection encounter between two massive bodies are presented. The results are valid through post-Newtonian order within general relativity. The gravitational waveform (transverse-traceless part of the metric perturbation tensor), the total luminosity and total emitted energy, the angular distribution of emitted energy (antenna pattern), and the frequency spectrum are discussed. A method of boosting the accuracy of these quantities to post-3/2-Newtonian order is presented. A numerical comparison of the results with previously reported results shows that the post-Newtonian method is reliable to better than 0.1% at v = 0.1c, to a few percent at v = 0.35c, and to 10-20% at v = 0.5c.

Turner, M.↗
NASA NTRS1978

Ultra-low magnetic field apparatus for a cryogenic gyroscope

An ultralow magnetic field apparatus for earth-based testing of a cryogenic gyroscope system designed for a satellite test of general relativity is described. The magnetic field apparatus makes use of a superconducting lead shield while also maintaining sufficient mechanical stability to obtain a gyroscope readout sensitivity of one arcsec over a limited range. A gyroscope environment of 2.3 times 10 to the minus seventh power gauss has been attained with the magnetic field shielding technique. The magnetic field apparatus is to be used with a three-axis London moment readout system.

Cabrera, B.↗
NASA NTRS1978

New trends in cosmology

A review of big-bang cosmology is presented, emphasizing the big-bang model, hypotheses on the origin of galaxies, observational tests of the big-bang model that may be possible with the Large Space Telescope, and the scale-covariant theory of gravitation. Detailed attention is given to the equations of general relativity, the redshift-distance relation for extragalactic objects, expansion of the universe, the initial singularity, the discovery of the 3-K blackbody radiation, and measurements of the amount of deuterium in the universe. The curvature of the expanding universe is examined along with the magnitude-redshift relation for quasars and galaxies. Several models for the origin of galaxies are evaluated, and it is suggested that a model of galaxy formation via the formation of black holes is consistent with the model of an expanding universe. Scale covariance is discussed, a scale-covariant theory is developed which contains invariance under scale transformation, and it is shown that Dirac's (1937) large-numbers hypothesis finds a natural role in this theory by relating the atomic and Einstein units.

Canuto, V. M.↗
NASA NTRS1979

To the solar foci

Earlier authors showed that the sun is likely to act as a lens for gravitational radiation, with focui in the outer solar system. They suggested that missions to these foci have the potential of directly measuring the density structure of the sun. Other applications include gravitational wave astronomy and tests of general relativity. This idea is reexamined, concentrating on the engineering aspects of focal missions; primarily spacecraft design and performance. Other topics studied include solar optics, gravitational wave detectors, navigation, and the design of missions for different purposes. Specifically, it is shown that shuttle launched chemical rockets have a substantial capability for reaching some foci; and that all can be reached with large payloads using nuclear isotope-electric propulsion.

Sonnabend, D.↗
NASA NTRS1978

New morphometric data for fresh lunar craters

Morphometric relations have been determined for 2598 fresh craters on the lunar nearside using data given in the catalog of Wood and Andersson (1978). For each of five principal morphological types, typified by Albategnius C, Biot, Sosigenes, Triesnecker, and Tycho, statistical relations are documented for the following: crater diameter and depth; floor diameter and crater diameter; central peak height and crater diameter; average wall slope and crater depth; central peak occurrence and crater diameter; occurrence of scallops or terraces and crater diameter. The first four relations generally confirm the conclusions of Pike (1977), but the last two differ from results reported by Smith and Sanchez (1973). Small (diameter less than 20 km) flat-floored craters formed in mare terrains are as much as 10% deeper than those formed in the highlands, and the depths of small bowl-shaped craters reflect even greater dependence on terrain. Larger, scalloped-walled craters are deeper in highland terrain than on the maria. Although wall failure does not occur until the crater diameter reaches 13 km, central peaks are found in flat floor craters as small as 2 km.

Wood, C. A.↗
NASA NTRS1980

Steady, Oscillatory, and Unsteady Subsonic and Supersonic Aerodynamics, production version (SOUSSA-P 1.1). Volume 1: Theoretical manual

Recent developments of the Green's function method and the computer program SOUSSA (Steady, Oscillatory, and Unsteady Subsonic and Supersonic Aerodynamics) are reviewed and summarized. Applying the Green's function method to the fully unsteady (transient) potential equation yields an integro-differential-delay equation. With spatial discretization by the finite-element method, this equation is approximated by a set of differential-delay equations in time. Time solution by Laplace transform yields a matrix relating the velocity potential to the normal wash. Premultiplying and postmultiplying by the matrices relating generalized forces to the potential and the normal wash to the generalized coordinates one obtains the matrix of the generalized aerodynamic forces. The frequency and mode-shape dependence of this matrix makes the program SOUSSA useful for multiple frequency and repeated mode-shape evaluations.

Morino, L.↗
NASA NTRS1979

Gyro precession and Mach's principle

The precession of a gyroscope is calculated in a nonrelativistic theory due to Barbour which satisfies Mach's principle. It is shown that the theory predicts both the geodetic and motional precession of general relativity to within factors of order 1. The significance of the gyro experiment is discussed from the point of view of metric theories of gravity and this is contrasted with its significance from the point of view of Mach's principle.

Eby, P.↗
NASA NTRS1980

The effects of seeing on the reflected spectrum of Uranus and Neptune

The results of a redetermination of the rotational periods of Uranus and Neptune, based on spectrograms obtained with the coude spectrograph of the 5 m Hale telescope, are presented. The effects of image motion on the shape of the spectral lines reflected by a planet rotating as a solid body and coherently scattering solar light, has been studied analytically. A general relation between the seeing transformed velocities at any point on the disk and those at the equator is established. It is shown that, for the case of Gaussian seeing, the brightness continuum of the smeared disk contains all the information required to derive the shape of the reflected lines. The shift, change in r.m.s. width, and asymmetry of the seeing transformed lines at the equator have been numerically evaluated for the brightness distribution of Uranus determined from Stratoscope II.

Muench, G.↗
NASA NTRS1978

Development of a London moment readout for a superconducting gyroscope

A gyroscope for verifying certain predictions of General Relativity is under development at Stanford. A method of measuring the gyroscope orientation based on the use of the London moment and a SQUID magnetometer is described. It is estimated that the required sensitivity of 1 milliarc-sec can be achieved in a bandwidth of 2.5 times 10 to the -6th Hz.

Anderson, J. T.↗
NASA NTRS1980

On Rosen's theory of gravity and cosmology

Formal similarities between general relativity and Rosen's bimetric theory of gravity were used to analyze various bimetric cosmologies. The following results were found: (1) physically plausible model universes which have a flat static background metric, have a Robertson-Walker fundamental metric, and which allow co-moving coordinates do not exist in bimetric cosmology. (2) it is difficult to use the Robertson-Walker metric for both the background metric (gamma mu nu) and the fundamental metric tensor of Riemannian geometry( g mu nu) and require that g mu nu and gamma mu nu have different time dependences. (3) A consistency relation for using co-moving coordinates in bimetric cosmology was derived. (4) Certain spatially flat bimetric cosmologies of Babala were tested for the presence of particle horizons. (5) An analytic solution for Rosen's k = +1 model was found. (6) Rosen's singularity free k = +1 model arises from what appears to be an arbitary choice for the time dependent part of gamma mu nu.

Barnes, R. C.↗
NASA NTRS1980

Test of relativistic gravitation with a space-borne hydrogen maser

The results of a test of general relativity with use of a hydrogen-maser frequency standard in a spacecraft launched nearly vertically upward to 10,000 km are reported. The agreement of the observed relativistic frequency shift with prediction is at the 70 x 10 to the -6th level.

Vessot, R. F. C.↗
NASA NTRS1980

Design aspects of a laser gravitational wave detector in space

Certain optical and mechanical aspects of a proposed laser gravitational wave antenna in space are briefly discussed. The proposed concept consists of a free-mass antenna with the test masses separated by a distance of 1,000,000 km. A laser heterodyne technique is employed to measure the distance change between test masses resulting from gravitational wave interaction. The proposed scheme is considered to offer the necessary sensitivity to detect gravitational radiation from binary stars predicted by General Relativity Theory.

Decher, R.↗
NASA NTRS1981

Computer circuit card puller

The invention generally relates to hand tools, and more particularly to an improved device for facilitating removal of printed circuit cards from a card rack characterized by longitudinal side rails arranged in a mutually spaced parallelism and a plurality of printed circuit cards extended between the rails of the rack.

Sawyer, R. V.↗