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At least 1,153 records · Page 64
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NASA NTRS1978

Earth Resources: A continuing bibliography with indexes, issue 16, January 1978

This bibliography lists 543 reports, articles, and other documents introduced onto the NASA scientific and technical information system between October 1 and December 31, 1977. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗
NASA NTRS1977

Atmospheric study relating to pad lift-off and entry landing

A relationship between the atmospheric general circulation and geophysical hydrodynamic experiments was sought by attempting to find a relationship between wave number and temperature gradient at mid-latitudes at 500 mb. To this end data were gathered from four winter seasons and analyzed. The statistical analysis failed to provide convincing support for the hypothesis of a direct relationship between wave number and temperature gradient, although an indication that the transient waves may be so related was noted.

King, R. L.↗
NASA NTRS1977

Earth resources: A continuing bibliography with indexes, issue 12, January 1977

This bibliography lists 526 reports, articles, and other documents introduced into the NASA scientific and technical information system between October 1976 and December 1976. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗
NASA NTRS1978

SeaSat-A Satellite Scatterometer (SASS) Validation and Experiment Plan

This plan was generated by the SeaSat-A satellite scatterometer experiment team to define the pre-and post-launch activities necessary to conduct sensor validation and geophysical evaluation. Details included are an instrument and experiment description/performance requirements, success criteria, constraints, mission requirements, data processing requirement and data analysis responsibilities.

Schroeder, L. C.↗
NASA NTRS1978

VLBI/Laser Intercomparison Project: Session 2

Recent experiments are described which directly intercompare very long baseline interferometry (VLBI) with laser ranging to artificial satellites by measuring the vector lengths of the same intercontinental baselines. These experiments are part of the VLBI/Laser-Intercomparison Project, a continuing task to assess the suitability of VLBI to various geophysical applications.

Fliegel, H. F.↗
NASA NTRS1978

Earth Resources: A continuing bibliography with indexes, issue 17

This bibliography lists 775 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1 and March 31, 1978. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗
NASA NTRS1978

Earth resources: A continuing bibliography with indexes, issue 18

This bibliography lists 434 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1 and June 30, 1978. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis.

Source record↗
NASA NTRS1978

Post-shock temperatures in minerals

Post-shock temperatures were measured in a wide variety of materials, including those of geophysical interest such as silicates by using an infrared detector to determine the brightness temperature of samples shocked to pressures in the range 5 to approximately 30 GPa. Measurements were made in the 4.5 to 5.75 micron and in the 7 to 14 micron wavelength ranges. Reproducible results, withe the temperatures in the two wavelength bands generally in excellent agreement, were obtained for aluminum-2024 (10.5 to 33 GPa; 125 to 260 C), stainless steel-304 (11.5 to 50 GPa; 80 to 350 C), crystalline quartz (5.0 to 21.5 GPa; 80 to 250 C) forsterite (7.5 to 28.0 GPa; approximately 30 to 160 C) and Bamble bronzite (6.0 to 26.0 GPa; approximately 30 to 225 C). Results are generally much higher at low pressures than the values calculated assuming a hydrodynamic rheology and isentropic release parallel to the Hugoniot but tend towards them at higher pressures.

Raikes, S. A.↗
NASA NTRS1976

The Seasat-A project - An overview

Scheduled for launch in the second quarter of calendar year 1978, the Seasat-A satellite is designed to provide all-weather global monitoring of sea surface temperature, significant wave height, surface wind speed and direction and departures from the marine geoid corresponding to ocean dynamic processes. These data will be obtained from an array of microwave instruments, two active ones (short pulse radar altimeter and wind field scatterometer) and one passive (scanning multichannel microwave radiometer). An experimental L-band synthetic aperture radar, operated on a selected basis for approximately four percent of the time, will provide land and ocean images with a resolution of 25 meters and a swath width close to 100 km for the study of coastal processes, sea ice and ocean wave characteristics. The mission objectives focus on an evaluation of the performance of the instruments in terms of their capabilities to characterize the desired geophysical quantities and the utility of such measurements to the study and exploitation of the world's oceans.

Dunne, J. A.↗
NASA NTRS1977

Stimulated plasma waves in the ionosphere

The reported discussion is concerned with longitudinal waves associated with electron motions. These waves are easily stimulated in the ionosphere by rocket- and satellite-borne RF sounders. Most of the observations of stimulated plasma waves in the ionosphere are based on ionograms obtained from the sounders carried on board five satellites, including Explorer 20, Alouette 1 and 2, and ISIS 1 and 2. The majority of the observations can be explained by considering the propagation of the sounder-stimulated plasma waves. Attention is given to aspects of plasma wave dispersion, linear phenomena, plasma wave instabilities and nonlinear phenomena, unexplained phenomena, diagnostic applications, geophysical and astrophysical applications, and a number of experiments planned for the future.

Benson, R. F.↗
NASA NTRS1978

Shear flow beneath oceanic plates - Local nonsimilarity boundary layers for olivine rheology

The principle of local similarity, which has been used to model the two-dimensional boundary layers in the oceanic upper mantle, permits calculation of the temperature, velocity, and stress fields with essentially analytic techniques. Finite difference numerical methods are hard pressed to resolve the detail required by the large variation of viscosity between the lithosphere and the asthenosphere. In this paper the local similarity approximation has been justified by quantitatively evaluating the effect of nonsimilarity due to viscous heating, nonlinear temperature- and pressure-dependent rheology, buoyancy, adiabatic cooling, etc. Nonsimilar effects produce only small modifications of the locally similar boundary layers; important geophysical observables such as surface heat flux and ocean floor topography are given to better than 10 percent by the locally similar solution. A posteriori evaluations of the terms neglected in the boundary layer simplification of the complete equations have been conducted on the locally similar temperature and velocity profiles close to the spreading ridge. The boundary layer models are valid to depths of 100 km at 3 m.y. and 10 km at 0.3 m.y.

Yuen, D. A.↗
NASA NTRS1978

Effect of a changing G on the moment of inertia of the earth

A recent value found by Nordtvedt and Will (1972) for the rate of increase of the moment of inertia of earth resulting from a decreasing G is shown to be based on conflicting physical assumptions. The corrected result for this restricted problem yields a rate of change almost twice as large. However, in a realistic treatment, additional purely geophysical causes must also be taken into account, and these imply a decreasing moment of inertia on a scale much outweighing the increase that would occur for any acceptable value of the derivative of G. This accords with the intrinsic acceleration of angular velocity established from ancient-eclipse data.

Lyttleton, R. A.↗
NASA NTRS1978

Seasat-A opens new phase in earth observations

The data output of the Seasat-A, the first satellite designed specifically for oceanographic observation, is described. Wave height and direction, ice distribution, surface wind speed and direction, ocean-surface temperature, and atmospheric water content will be monitored by the satellite. Imaging radar, microwave scatterometer, microwave radiometer and visual and infrared radiometer experiments are included in the Seasat-A observing program. Two types of orbits have been developed: a near-repeat cycle of three days, and a near-repeat cycle of 25 days. Both orbit types offer fine coverage (18.5 km crossing separations) of the earth. Synthetic aperture radar data on computer-compatible tapes and geophysical data records available through the Seasat-A mission are described.

Cutting, E.↗
NASA NTRS1978

Thermal evolutions of the terrestrial planets

Theoretical models are formulated for the thermal evolution of the moon, Mercury, Mars, Venus, and hypothetical minor planets, with consideration of conduction, solid-state convection, and differentiation. A variety of geological, geochemical and geophysical data is used to constrain both the present-day temperatures and the thermal histories of the planetary interiors. The data imply that the planets were heated during or shortly after formation and that all the terrestrial planets started differentiating early in their history. The size of the planet is the primary factor in determining its present-day thermal state. A planetary body with radius less than 1000 km is unlikely to reach melting, given heat source concentrations similar to terrestrial values and in the absence of intensive early heating.

Toksoz, M. N.↗
NASA NTRS1978

Thermal history and evolution of Mars

A thermal history of Mars is developed on the basis of available geophysical and geological data, including information obtained by the Viking missions. Specification of initial temperatures, composition and heat sources takes into account conduction and subsolidus mantle convection. Four phases in the Martian thermal history are distinguished. Core formation and crust differentiation occur during the first billion years. Partial melting, differentiation and outgassing of the mantle have taken place by the end of 3 billion years. In the 3- to 4-billion year epoch, the lithosphere thickens and the partial melt zone becomes deeper. By 4.6 billion years after commencement of evolution, volcanic activity has subsided, while the partial melt zone continues to shrink.

Toksoz, M. N.↗
NASA NTRS1978

Photochemical-radiative damping and instability in the stratosphere. II Numerical results

In a paper by Strobel (1977), opacity effects on the joint photochemical-radiative relaxation in the stratosphere were evaluated by a linear perturbation analysis. Significant reductions in the photochemical acceleration of the thermal relaxation rate and the ozone photochemical relaxation rate were obtained in the upper stratosphere as a result of opacity changes. For very large vertical scale height ozone density perturbations, amplifying solutions were generated by large opacity changes in the O3 dissociation and heating rates. Such solutions could indicate that the stratosphere does not possess an equilibrium ozone concentration. In the present paper, some illustrative numerical calculations are presented to demonstrate the properties of the amplifying solutions. The results indicate that ungeophysically large disturbances are required and that they cease growth before attainment of geophysically interesting amplitudes, and decay to the unperturbed state.

Strobel, D. F.↗
NASA NTRS1977

Lunar Science Conference, 8th, Houston, Tex., March 14-18, 1977, Proceedings. Volume 1 - The moon and the inner solar system. Volume 2 - Petrogenetic studies of mare and highland rocks. Volume 3 - Planetary and lunar surfaces

Solar system processes are considered along with the origin and evolution of the moon, planetary geophysics, lunar basins and crustal layering, lunar magnetism, the lunar surface as a planetary probe, remote observations of lunar and planetary surfaces, earth-based measurements, integrated studies, physical properties of lunar materials, and asteroids, meteorites, and the early solar system. Attention is also given to studies of mare basalts, the kinetics of basalt crystallization, topical studies of mare basalts, highland rocks, experimental studies of highland rocks, geochemical studies of highland rocks, studies of materials of KREEP composition, a consortium study of lunar breccia 73215, topical studies on highland rocks, Venus, and regional studies of the moon. Studies of surface processes, are reported, taking into account cratering mechanics and fresh crater morphology, crater statistics and surface dating, effects of exposure and gardening, and the chemistry of surfaces.

Merril, R. B.↗
NASA NTRS1977

Some constraints on the thermal history of the lunar magma ocean

If the accumulating evidence is accepted that the outer portion of the moon was molten for 100-200 million years, it is clear that a permanent insulating surface layer existed over nearly all of that epoch. Considerations of crustal stability against break-up and foundering lead to the view that this insulating blanket must have been an early-forming plagioclase-rich layer light enough to float on the hot magma. It is found that radiometric age-dating evidence implies a fairly specific history for the solidification of the lunar magma ocean. The possibility is anticipated that geochronological and petrological constraints will be sufficient to narrow the range of allowed geophysical and geochemical models. It is hoped that such a study will make it possible to deduce the original depth, and hence, the composition of the lunar magma ocean. If the moon accreted homogeneously, the composition of the magma ocean will also be that of the whole moon, and hence such models should allow estimation of the bulk lunar composition.

Herbert, F.↗