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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

The geology and geophysics of Mars

The current state of knowledge concerning the regional geology and geophysics of Mars is summarized. Telescopic observations of the planet are reviewed, pre-Mariner models of its interior are discussed, and progress achieved with the Mariner flybys, especially that of Mariner 9, is noted. A map of the Martian geological provinces is presented to provide a summary of the surface geology and morphology. The contrast between the northern and southern hemispheres is pointed out, and the characteristic features of the surface are described in detail. The global topography of the planet is examined along with its gravitational field, gravity anomalies, and moment of inertia. The general sequence of events in Martian geological history is briefly outlined.

Saunders, R. S.↗
NASA NTRS1978

A bibliography of planetary geology principal investigators and their associates, 1976-1978

This bibliography cites publications submitted by 484 principal investigators and their associates who were supported through NASA's Office of Space Sciences Planetary Geology Program. Subject classifications include: solar system formation, comets, and asteroids; planetary satellites, planetary interiors, geological and geochemical constraints on planetary evolution; impact crater studies, volcanism, eolian studies, fluvian studies, Mars geological mapping; Mercury geological mapping; planetary cartography; and instrument development and techniques. An author/editor index is provided.

Source record↗
NASA NTRS1978

Implications of cavity, topographic and geologic influences on tilt and strain observations

Tilt and strain observations are importantly (pathologically at the 100%, typically at the few 10s% level) affected by cavities, topography, and geological inhomogenities; gravity observation are practically unaffected. The traditional earth tide observatory and abandoned mine or tunnel is a very poor place to measure body tides because of the complicated cavities, topography and geology. Instead, the ideal site for observing the body tide is in flat terrain with horizontally layered, mechanically homogeneous geology. Strain will be measured with long surface- or trench-mounted laser strain meters and tilt with long, surface- or trench mounted liquid levels, or with borehole tiltmeters. Horizontal geological discontinuities can produce large perturbations of the tilt and strain tides, and these perturbations, using the known homogeneous tidal strains and tilts, can be used in exploring local structure in favorable cases and, through possible time variations of tidal admittances, in predicting earthquakes.

Harrison, J. C.↗
NASA NTRS1980

Historical sketch: Radar geology

A chronological assessment is given of the broad spectra of technology associated with radar geology. Particular attention is given to the most recent developments made in the areas of microwave Earth resources applications and geologic remote sensing from aircraft and satellite. The significance of space derived radar in geologic investigations is discussed and the scientific basis for exploiting the sensitivity of radar signals to various aspects of geologic terrain is given.

Macdonald, H.↗
NASA NTRS1982

A bibliography of planetary geology principal investigators and their associates, 1981 - 1982

Over 800 publications submitted by researchers supported through NASA's Planetary Geology Program are cited and an author/editor index is provided. Entries are listed under the following subjects: (1) general interest topics; (2) solar system, comets, asteroids, and small bodies; (3) geologic mapping, geomorphology, and stratigraphy; (4) structure, tectonics, geologic and geophysical evolution; (5) impact craters: morphology, density, and geologic studies; (6) volcanism; (7) fluvial, mass wasting, and periglacial processes; (8) Eolian studies; (9) regolith, volatile, atmosphere, and climate; (10) remote sensing, radar, and photometry; and (11) cartography, photogrammetry, geodesy, and altimetry.

Plescia, J. B.↗
NASA NTRS1982

Analysis of the characteristics appearing in LANDSAT multispectral images in the geological structural mapping of the midwestern portion of the Rio Grande do Sul shield

The central-western part of Rio Grande do Sul Shield was geologically mapped to test the use of MSS-LANDSAT data in the study of mineralized regions. Visual interpretation of the images a the scale of 1:500,000 consisted, in the identification and analysis of the different tonal and textural patterns in each spectral band. After the structural geologic mapping of the area, using visual interpretation techniques, the statistical data obtained were evaluated, specially data concerning size and direction of fractures. The IMAGE-100 system was used to enlarge and enhance certain imagery. The LANDSAT MSS data offer several advantages over conventional white and black aerial photographs for geological studies. Its multispectral characteristic (band 6 and false color composition of bands 4, 5 and 7 were best suitable for the study). Coverage of a large imaging area of about 35,000 sq km, giving a synoptical view, is very useful for perceiving the regional geological setting.

Parada, N. D. J.↗
NASA NTRS1982

Resolution versus speckle relative to geologic interpretability of spaceborne radar images - A survey of user preference

A survey conducted to evaluate user preference for resolution versus speckle relative to the geologic interpretability of spaceborne radar images is discussed. Thirteen different resolution/looks combinations are simulated from Seasat synthetic-aperture radar data of each of three test sites. The SAR images were distributed with questionnaires for analysis to 85 earth scientists. The relative discriminability of geologic targets at each test site for each simulation of resolution and speckle on the images is determined on the basis of a survey of the evaluations. A large majority of the analysts respond that for most targets a two-look image at the highest simulated resolution is best. For a constant data rate, a higher resolution is more important for target discrimination than a higher number of looks. It is noted that sand dunes require more looks than other geologic targets. At all resolutions, multiple-look images are preferred over the corresponding single-look image. In general, the number of multiple looks that is optimal for discriminating geologic targets is inversely related to the simulated resolution.

Ford, J. P.↗
NASA NTRS1984

Geology of Dione

Dione is one of the most geologically complex of the Saturnian satellites. Crater counts and surface morphology indicates the geologic units observed are of variable age and origin. In an attempt to understand the processes which have affected Dione, a geologic map was prepared. Several geologic units were identified; ancient heavily cratered terrain, two plains units: cratered plains and lightly cratered plains, lobate deposits, crater rim deposits and bright wispy materials.

Plescia, J. B.↗
NASA NTRS1984

Mapping and geological analysis of Mercury radar data

Although many radar profiles and images of the area within 20 deg of Mercury's equator had been obtained from 1971 to 1981, at both Goldstone and Arecibo radar facilities, surprisingly little geological analysis had been done with these data until recently. Topographic profiles and radar roughness reflectivity images which can be derived from these data will be crucial in completing the geological mapping of Mercury now underway at the U.S. Geological Survey. Processing of available radar data must be completed to establish any systematic relationship between radar reflectivities and roughness, density, dielectric constant, and other related geological parameters. Specific tasks accomplished for these purposes include the following. Documentation was located and searched to establish the type and quantity of Goldstone 12.5 cm radar observations which were available for Mercury. Data has been collected during approximately 50 observation periods from 1971 to 1981. About half of the data, collected during 1972 and 1973, have been processed, but without adequate documentation. A standardized, well-documented procedure for processing and analysis for all Goldstone Earth-based observations of Mercury was established.

Clark, P. E.↗
NASA NTRS1984

Mercury: Topographic and geologic data from Earth-based radar observations

Significant new geologic information has been revealed by comparing 1:5 million scale geologic maps of the equatorial zone quadrangles of Mercury (H-6, H-7 and H-8) to Earth-based elevation profiles and surface reflectivity maps of Mercury obtained in the early 1970's at the Arecibo (PR) and Goldstone (CA) radar facilities. These data consist of 23 Goldstone images and profiles of polarized return data at 12.5-cm wavelength and one Arecibo profile. Radar data with 150-m vertical accuracy and 10- to 20-km horizontal resolution are available for areas between latitudes 13 N. and 11 S. In general, these data sets show excellent correlation between: (1) relative elevation and roughness differences that are reflected by mapped geologic contacts; (2) mapped ridges and scarps that display distinctive radar signatures; and (3) position and morphology of crater-and-basin topographic elements. Inferences can also be drawn about topographic and geologic terrain beyond the area imaged by Mariner 10 cameras.

Strobell, M. E.↗
NASA NTRS1984

Planetary geology in the 1980s

The geologic aspects of solar system studies are defined and the goals of planetary geology are discussed. Planetary geology is the study of the origin, evolution, and distribution of matter condensed in the form of planets, satellites, asteroids, and comets. It is a multidisciplinary effort involving investigators with backgrounds in geology, chemistry, physics, astronomy, geodesy, cartography, and other disciplines concerned with the solid planets. The report is primarily restricted to the kinds of experiments and observations made through unmanned missions.

Veverka, J.↗
NASA NTRS1985

Mapping and Geological Analysis of Mercury and Venus Radar Ranging Data

Although many radar profiles and images of the areas within 20 deg of Mercury's equator had been obtained from 1971, at both Goldstone and Arecibo radar facilities, surprisingly little geological analysis had been done with these data until recently. Topographic profiles and radar roughness reflectivity images which can be derived from these data will be crucial in completing the geological mapping of Mercury now underway at the U.S. Geological Survey. Earth based radar observations of Mercury and the other terrestrial planets as well are a potentially very valuable tool in the determination of the physical nature of their surfaces. Processing of available radar data must be completed to establish any systematic relationship between raar reflectivities and roughness, density, dielectric constant, and other related geological parameters.

Clark, P. E.↗
NASA NTRS1983

Frontiers for geological remote sensing from space; Geosat Workshop, 4th, Flagstaff, AZ, June 12-17, 1983, Report

Consideration is given to: the applications of near-infrared spectroscopy to geological reconnaissance and exploration from space; imaging systems for identifying the spectral properties of geological materials in the visible and near-infrared; and Thematic Mapper (TM) data analysis. Consideration is also given to descriptions of individual geological remote sensing systems, including: GEO-SPAS; SPOT; the Thermal Infrared Multispectral Scanner (TIMS); and the Shuttle Imaging Radars A and B (SIR-A and SIR-B). Additional topics include: the importance of geobotany in geological remote sensing; achromatic holographic stereograms from Landsat MSS data; and the availability and applications of NOAA's non-Landsat satellite data archive.

Henderson, F. B.↗
NASA NTRS1985

Report of the Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins

The Workshop on Geologic Applications of Remote Sensing to the Study of Sedimentary Basins, held January 10 to 11, 1985 in Lakewood, Colorado, involved 43 geologists from industry, government, and academia. Disciplines represented ranged from vertebrate paleontology to geophysical modeling of continents. Deliberations focused on geologic problems related to the formation, stratigraphy, structure, and evolution of foreland basins in general, and to the Wind River/Bighorn Basin area of Wyoming in particular. Geological problems in the Wind River/Bighorn basin area that should be studied using state-of-the-art remote sensing methods were identified. These include: (1) establishing the stratigraphic sequence and mapping, correlating, and analyzing lithofacies of basin-filling strata in order to refine the chronology of basin sedimentation, and (2) mapping volcanic units, fracture patterns in basement rocks, and Tertiary-Holocene landforms in searches for surface manifestations of concealed structures in order to refine models of basin tectonics. Conventional geologic, topographic, geophysical, and borehole data should be utilized in these studies. Remote sensing methods developed in the Wind River/Bighorn Basin area should be applied in other basins.

Lang, H. R.↗
NASA NTRS1986

A geologic atlas of TIMS data

In the three years since the first data were taken, it was well demonstrated that the Thermal Infrared Multispectral Scanner (TIMS), properly used, can be a most valuable tool for the geologist. Compilation of the TIMS data into a geological atlas was felt to be useful. Several data sets were extensively studied to establish TIMS as a geologic tool and to explore the optimum enhancement techniques. It was found that a decorrelation stretch of bands 1, 3, and 5 enhance the data to a form that is very useful and this enhancement will be used in the geologic atlas along with an accompanying geologic map and description. Many data sets are well published and familiar to TIMS users, but there are some sets that, for lack of time and funds, were not thoroughly studied or published. A short description of these least studied sets of data is presented. The images presented along with the many previously studied and published TIMS images constitute an enormously useful set of information for the geologist in the 8 to 10 micron range.

Abbott, Elsa↗
NASA NTRS1988

Martian sample sites: Examples based on a global geologic perspective

Ten areas were selected that each include several rock units of varying lithology and age. These areas were chosen to optimize the geologic and chronologic data return from Mars. Geologic mapping and stratigraphic studies identify stratigraphic ages, rock types, and information on Martian geologic history that samples of a given site may yield. Volcanic rocks occur over much of the planet and in virtually all stratigraphic positions, and they are amenable to radioisotopic dating. Therefore, a reasonable and essential goal for a sample return mission is to return datable rocks from widely varying strata. Generally, about three or four major geologic units can be sampled at any of the given sites, most of which can probably be dated. The Mars Observer mission will aid greatly in interpreting lithology and defining contacts at the high resolution required to actually pinpoint good sample acquisition sites within these areas.

Scott, D. H.↗
NASA NTRS1989

Plate motions and deformations from geologic and geodetic data

The very long baseline interferometry (VLBI) measurements made in the western U.S. since 1979 provide discrete samples of the temporal and spatial deformation field. The interpretation of the VLBI derived rates of deformation requires an examination of geologic information and more densely sampled ground based geodetic data. Triangulation and trilateration data measured on two regional networks, one in the central Mojave Desert and one in the Coast Ranges east of the San Andreas fault, were processed. At the spatial scales spanned by these local geodetic networks, auxiliary geologic and geophysical data were utilized to examine the relation between measured incremental strain and the accommodation of strain seen in local geologic structures, strain release in earthquakes, and principal stress directions inferred from in situ measurements. VLBI data was also processed from stations distributed across the Pacific-North America plate boundary zone in the western U.S. The VLBI data were used to constrain the integrated rate of deformation across portions of the continental plate boundary in California and to provide a tectonic framework to interpret regional geodetic and geologic studies.

Jordan, Thomas H.↗
NASA NTRS1988

Stratigraphy and geologic history of Mercury

The geologic evolution of Mercury based on the Mariner-10 mission data is discussed. As reconstructed through photogeological analysis of global geologic relations of rock-stratigraphic units, Mercury's geologic history is shown to involve intensive early impact bombardment and widespread resurfacing by volcanic lavas. Evidence is presented to indicate that this volcanic activity essentially ended as much as 3 Gyr ago, with most of the major geologic events being completed within the first 1 to 1.5 Gyr of Mercurian history.

Spudis, Paul D.↗