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At least 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Geology of the Imbrium Basin Apennine Mountains and relation to the Apollo 15 landing site

Detailed mapping of the Imbrium Basin Apennine Mountains has emphasized several important factors in the geologic evolution of this region. Pre-Imbrian topography was composed of two types of landforms: (1) the nearby Serenitatis, South Imbrium, Aestuum, and Vaporum basins which produced widely spaced regional lows and a sequence of basin deposits; (2) pre-Imbrian craters that reworked existing basin deposits and produced local topographic lows. The sequence of events during the Imbrium impact can be summarized as follows: intensive structural uplift along the Apennine Front occurred prior to the emplacement of ballistic ejecta. Ejecta became more discontinuous toward the backslope and produced radial texture by sedimentary erosional and depositional processes. Post-ejecta-emplacement downfaulting exposed pre-Imbrian deposits along the front and caused severe seismic disturbances that reworked many of the previous units and accentuated pre-basin structures. Tectonic mapping and orbital geophysical data support the idea that little structural modification has occurred in the Apennines since their formation 3.9 b.y. ago.

Spudis, P.↗
NASA NTRS1977

Precision gravity detection - Gradiometry and/or radiometry

Current knowledge concerning the earth's gravity field is limited to about 1500-2000 km resolution. However, the resolution of gravity anomalies having a spatial extent of 100-1000 km over the entire globe is needed for important geophysical and geodetic applications. In the near future satellite altimetry will be used to determine the ocean geoid at the 10 cm - 1 m level. In order to provide a similar level of resolutions over the land regions, there exists a need for utilizing new promising techniques such as gravity gradiometry and new radiometric measurements, viz., satellite-to-satellite tracking. Satellite-to-satellite tracking techniques have shown potential for improving the medium wavelength component of the gravity field. The gravity gradiometer has not yet been tested on board a satellite. The reported analysis includes a simplified theoretical model to compare the effectiveness of the gradiometer measurements and radiometric measurements for high resolution gravity field determination, and the direct estimation of local gravity anomalies represented by point masses using a simulated gravity gradiometer and satellite-to-satellite tracking data.

Ananda, M.↗
NASA NTRS1978

The EUV flux inferred from AE-C He/+/ abundances

The ionization rate of helium in the thermosphere is inferred from He(+) abundances determined by instrumentation on the Atmosphere Explorer-C satellite. The inferred ionization rate is independent of the particular geophysical parameters of the thermosphere for solar zenith angles less than 80 deg and altitudes between 280 and 360 km. The ionization rate is consistent with a value calculated from the EUV flux of Hinteregger (1976) below 504 A.

Oppenheimer, M.↗
NASA NTRS1978

Numerical method for solution of systems of non-stationary spatially one-dimensional nonlinear differential equations

A computational scheme and a standard program is proposed for solving systems of nonstationary spatially one-dimensional nonlinear differential equations using Newton's method. The proposed scheme is universal in its applicability and its reduces to a minimum the work of programming. The program is written in the FORTRAN language and can be used without change on electronic computers of type YeS and BESM-6. The standard program described permits the identification of nonstationary (or stationary) solutions to systems of spatially one-dimensional nonlinear (or linear) partial differential equations. The proposed method may be used to solve a series of geophysical problems which take chemical reactions, diffusion, and heat conductivity into account, to evaluate nonstationary thermal fields in two-dimensional structures when in one of the geometrical directions it can take a small number of discrete levels, and to solve problems in nonstationary gas dynamics.

Morozov, S. K.↗
NASA NTRS1978

Advanced designs for fluid flow visualization

Research was carried out on existing and new designs for minimally intrusive measurement of flow fields in the Geophysical Fluid Flow Cell and the proposed Atmospheric General Circulation Experiment. The following topics are discussed: (1) identification and removal of foreign particles, (2) search for higher dielectric photochromic solutions, (3) selection of uv light source, (4) analysis of refractive techniques and (5) examination of fresnel lens applicability.

Source record↗
NASA NTRS1978

Earth Resources: A continuing bibliography with indexes, issue 19

This bibliography lists 337 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System between July 1 and September 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

Analysis and geological interpretation of gravity data from GEOS-3 altimeter

A number of detailed gravimetric geoids of portions of the world's oceans from marine gravity measurements were constructed. The geoids were constructed by computing 1 x 1 deg or 10 x 10 deg averages of free-air anomaly data and subtracting these values from currently used satellite derived Earth models. The resulting difference gravity anomalies are then integrated over a sphere using a simplified form of Stoke's equation to obtain a difference geoid. This difference geoid is added to the satellite derived model to obtain a 1 x 1 deg or 10 x 10 deg total gravimetric geoid. The geoid undulations are studied by comparison of the altimeter measurements with the morphology of the ocean floor. Utilizing a combination of altimetry data, gravity and seismic reflection data, geophysical models of the earth can be constructed.

Talwani, M.↗
NASA NTRS1979

Post-shock temperatures in minerals

An experimental technique was developed for measuring post-shock temperatures in a wide variety of materials, including those of geophysical interest such as silicates. The technique uses an infrared radiation detector to determine the brightness temperature of samples shocked to pressures in the range 5 to approximately 30 GPa; in these experiments measurements were made in two wavelength ranges (4.5 to 5.75 microns and 7 to 14 microns). Reproducible results, with 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). It is concluded that release adiabat data should be used, wherever available, for calculations of residual temperature, and that adequate descriptions of the shock and release processes in minerals are more complex than generally assumed.

Raikes, S. A.↗
NASA NTRS1978

High-precision gravimetric survey in support of lunar laser ranging at Haleakala, Maui, 1976 - 1978

The planning, observations and adjustment of high-precision gravity survey networks established on the islands of Maui and Oahu as part of the geodetic-geophysical program in support of lunar laser ranging at Haleakala, Maui, Hawaii are described. The gravity survey networks include 43 independently measured gravity differences along the gravity calibration line from Kahului Airport to the summit of Mt. Haleakala, together with some key points close to tidal gauges on Maui, and 40 gravity differences within metropolitan Honolulu. The results of the 1976-1978 survey are compared with surveys made in 1961 and in 1964-1965. All final gravity values are given in the system of the international gravity standardization net 1971 (IGSN 71); values are obtained by subtracting 14.57 mgal from the Potsdam value at the gravity base station at the Hickam Air Force Base, Honolulu.

Schenck, B. E.↗
NASA NTRS1979

Tables of thermospheric temperature, density and composition derived from satellite and ground based measurements. Volume 1: Ap=4

The tables contain the neutral temperature, neutral densities for N2, O2, O, Ar, He and H, mean molecular weight, and total mass density as predicted by the Mass Spectrometer and Incoherent Scatter empirical thermosphere model for selected altitudes, latitudes, local times, days and other geophysical conditions. The model is based on a least squares fit to density data from mass spectrometers on five satellites and temperature data from four incoherent scatter stations, providing coverage for most of solar sunspot cycle 20. Included in the model data base are longitudinally average N3, He, and O densities from the OGO-6 mass spectrometer longitudinally average N2, He, O and Ar densities from the AEROS-A (NATE) mass spectrometer the N2, He, O, and Ar densities from the San Marco 3 mass spectrometer the N2 densities from the AE-B mass spectrometer and the N2, He, O, and Ar densities from the AE-C (OSS, NACE, NATE) mass spectrometers. The O2 and H densities are inferred using ion mass spectrometer data from AE-C (BIMS). Neutral exospheric temperature data are included from Arecibo, St. Santin, Millstone Hill and Jicamarca.

Hedin, A. E.↗
NASA NTRS1979

Tables of thermospheric temperature, density and composition derived from satellite and ground based measurements. Volume 3: Ap=100

The neutral temperature, neutral densities for N2, O2, O, Ar, He and H, mean molecular weight, and total mass density as predicted by the Mass Spectrometer and Incoherent Scatter empirical thermosphere model are presented in tabular form. The predictions are based on selected altitudes, latitudes, local times, days and other geophysical conditions. The model is dependent on a least squares fit to density data from mass spectrometers on five satellites and temperature data from four incoherent scatter stations, providing coverage for most of solar sunspot cycle 20.

Hedin, A. E.↗
NASA NTRS1979

Earth Resources: A continuing bibliography with indexes, issue 20

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system between October 1 and December 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

Merged infrared catalogue

A compilation of equatorial coordinates, spectral types, magnitudes, and fluxes from five catalogues of infrared observations is presented. This first edition of the Merged Infrared Catalogue contains 11,201 oservations from the Two-Micron Sky Survey, Observations of Infrared Radiation from Cool Stars, the Air Force Geophysics Laboratory four Color Infrared Sky Survey and its Supplemental Catalog, and from Catalog of 10 micron Celestial Objects (HALL). This compilation is a by-product of a computerized infrared data base under development at Goddard Space Flight Center; the objective is to maintain a complete and current record of all infrared observations from 1 micron m to 1000 micron m of nonsolar system objects. These observations are being placed into a standardized system.

Schmitz, M.↗
NASA NTRS1978

Applications of Geodesy to Geodynamics, an International Symposium

Geodetic techniques in detecting and monitoring geodynamic phenomena are reviewed. Specific areas covered include: rotation of the earth and polar motion; tectonic plate movements and crustal deformations (space techniques); horizontal crustal movements (terrestrial techniques); vertical crustal movements (terrestrial techniques); gravity field, geoid, and ocean surface by space techniques; surface gravity and new techniques for the geophysical interpretation of gravity and geoid undulation; and earth tides and geodesy.

Mueller, I. I.↗
NASA NTRS1978

Principles of very-long-baseline interferometry

The basic principles of very-long-baseline interferometry as related to its use in the determination of vector baselines, polar motion, and earth rotation are presented. Aspects relevant to geodetic applications that involve observations of extragalactic radio sources are covered. The instrumentation used in these observations and the basic observables and their simplest interpretation are described. Complications of the interpretation due to the various geophysical 'signals' and nongeophysical 'noise' that affect the observables are considered.

Shapiro, I. I.↗
NASA NTRS1978

Problems and advances in monitoring horizontal strain

The modern instrumentation is described for use in geodesy for the detection of the deformations of the crust of the earth. Problems are listed. Needs are discussed for the survey of the physical quantities of interest in geodesy, geology, geophysics, and engineering such as the strain invariants, the optimal network of baselines and the accuracy. An analytic method is also given for the computation of the effect of a source of dilatation in a spherical earth.

Caputo, M.↗
NASA NTRS1978

The AFGL absolute gravity program

A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

Hammond, J. A.↗