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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 181 records · Page 10
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NASA NTRS1985

Mars: Stratigraphy of Western Highlands and Polar Regions

Geologic mapping and stratigraphic studies of Mars based on Viking images improved knowledge of the relative age and occurrence of geologic units on a global scale. Densities of geologic units or features during the Noarchian, Hesperian, and Amazonian periods are indicated for the North and South polar regions as well as the equatorial region of Mars. Cumulative counts of crater size frequencies for craters larger than 2 km in diameter on plateau units mapped in the western region of Mars counts indicate that the plateau terrain as a whole was thinly resurfaced during the Hesperian Period, and a large proportion of pre-existing craters less than 10 to 15 km in diameter was buried. The formation of northern plains, subpolar highlands, and both polar regions is also described.

Tanaka, K. L.↗
NASA NTRS1985

Microwave responses of the western North Atlantic

Features and objects in the Western North Atlantic Ocean - the Eastern Seaboard of the United States - are observed from Earth orbit by passive microwaves. The intensities of their radiated flux signatures are measured and displayed in color as a microwave flux image. The features of flux emitting objects such as the course of the Gulf Stream and the occurrence of cold eddies near the Gulf Stream are identified by contoured patterns of relative flux intensities. The flux signatures of ships and their wakes are displayed and discussed. Metal data buoys and aircraft are detected. Signal to clutter ratios and probabilities of detection are computed from their measured irradiances. Theoretical models and the range equations that explain passive microwave detection using the irradiances of natural sources are summarized.

Stacey, J. M.↗
NASA NTRS1984

Estimates of the geostrophic stream function in the western North Pacific from XBT surveys

Bernstein and White (1981) have argued that the 300 m temperature field in the western North Pacific reflects the 100/1000 dbar geostrophic stream function of the upper ocean where 100/1000 dbar implies the 100 dbar surface relative to the 1000 dbar surface. The correlation between upper ocean dynamic height and temperature in this region provides the basis for their argument. The involved relationship suggests that it may be possible to monitor the relative upper ocean geostrophic transport, as well as energy relations and heat fluxes with expendable bathythermograph (XBT) surveys. Certain discrepancies between data from different sources are felt to result from problems with the XBT observations. The present investigation is concerned with the determination of the ability of XBT surveys to estimate geostrophic currents, taking into account a comparison of directly measured data with estimated shears. Discrepancies are found to be related to an underestimation of the dynamic height gradients.

Koblinsky, C. J.↗
NASA NTRS1984

Gravity anomalies and the structure of western Tibet and the southern Tarim Basin

Gravity anomalies across the western part of the Tarim Basin and the Kunlun mountain belt show that this area is not in local isostatic equilibrium. These data can be explained if a strong plate underlying the Tarim Basin extends southwestward beneath the belt at least 80 km and supports part of the topography of northwest Tibet. This corroborates Norin's inference that late Tertiary crustal shortening has occurred in this area by southward underthrusting of the Tarim Basin beneath the Kunlun. This study places a lower bound on the amount of underthrusting.

Lyon-Caen, H.↗
NASA NTRS1985

The Western Aeronautical Test Range of NASA Ames Research Center

An overview of the Western Aeronautical Test Range (WATR) of NASA Ames Research Center (ARC) is presented in this paper. The three WATR facilities are discussed, and three WATR elements - mission control centers, communications systems, real-time processing and display systems, and tracking systems - are reviewed. The relationships within the NASA WATR, with respect to the NASA aeronautics program, are also discussed.

Moore, A. L.↗
NASA NTRS1983

Contrasts in winter-summer cloudiness over the Western Hemisphere during the FGGE

An examination is undertaken of techniques for the representation of satellite-derived seasonal cloud climatology statistics, together with the phenomenological contrasts evident in extended cloud fields from one season to the next. Attention is given to results from a winter and a summer period over the Western Hemisphere in 1979. Cloud cover information has been derived from the GOES-East geosynchronous satellite; the data sets used consist of 15-day periods of hourly, 8-km resolution visual and IR digital measurements.

Smith, E. A.↗
NASA NTRS1985

The Use of AIS Data for Identifying and Mapping Calcareous Soils in Western Nebraska

The identification of calcareous soils, through unique spectral responses of the vegetation to the chemical nature of calcareous soils, can improve the accuracy of delineating the boundaries of soil mapping units over conventional field techniques. The objective of this experiment is to evaluate the use of the Airborne Imaging Spectrometer (AIS) in the identification and delineation of calcareous soils in the western Sandhills of Nebraska. Based upon statistical differences found in separating the spectral curves below 1.3 microns, calcareous and non-calcareous soils may be identified by differences in species of vegetation. Additional work is needed to identify biogeochemical differences between the two soils.

Samson, S. A.↗
NASA NTRS1986

Preliminary report on the geology and gold mineralization of the South Pass granite-greenstone terrain, Wind River Mountains, western Wyoming (US)

The South Pass granite-greenstone terrain lies near the southern tip of the Wind River Mountains of western Wyoming. This Archean supracrustal pile has been Wyoming's most prolific source of gold and iron ore. From 1962 to 1983, more than 90 million tons of iron ore were recovered from oxide-facies banded iron formation, and an estimated 325,000 ounces of gold were mined from metagreywacke-hosted shears and associated placers. Precambrian rocks at South Pass are unconformably overlain by Paleozoic sediments along the northeast flank, and a Tertiary pediment buries Archean supracrustals on the west and south. To the northwest, the supracrustals terminate against granodiorite of the Louis Lake batholith; to the east, the supracrustals terminate against granite of the Granite Mountains batholith. The Louis Lake granodiorite is approximately 2,630 + or - 20 m.y. old, and the Granite Mountains granite averages 2,600 m.y. old. The geometry of the greenstone belt is best expressed as a synform that has been modified by complex faulting and folding. Metamorphism is amphibolite grade surrounding a small island of greenschist facies rocks. The younger of the Archean supracrustal successions is the Miners Delight Formation. This unit yielded a Rb-Sr isochron of 2,800 m.y. A sample of galena from the Snowbird Mine within the Miners Delight Formation yielded a model age averaging 2,750 m.y. The Snowbird mineralization appears to be syngenetic and is hosted by metavolcanics of calc-alkaline affinity. Discussion follows.

Hausel, W. D.↗
NASA NTRS1986

Evidence for structural stacking and repetition in the greenstones of the Kalgoorlie district, western Australia

Most previous stratigraphic interpretations of the southern part of the Norseman-Wiluna Greenstone Belt have proposed polycyclic sequences. These invoked two and sometimes three successive suites of mafic and/or ultimafic volcanics and intrusives separated by felsic volcanics and immature clastic sediments, however no distinctive lithological differences were reported between successive mafic-ultramaic sequences. When interpretations of the area further to the north are integrated, a total of four separate major mafic-ultramafic uites emerges for a large part of the Norseman-Wiluna Belt. Although the author does not intent to imply that all polycyclic stratigraphies are wrong in principle such a situation seems suspiciously over-complex and stimulates the need to look critically at the individual areas where the stratigraphies have seen erected. For the Kalgoorlie area in the south, some of the schemes have already provoked scepticism and a simpler model consisting of one cycle subject to structural repetition has been evolved by workers in the Geological Survey of Western Australia for part of this area. The latter drew attention to the carbon copy similarity between the elements of some polycyclic stratigraphies. Much more regionally extensive integrated structural and stratigraphic data is still required to evaluate the relationship between structure and stratigraphy more fully, an objective substantially limited by poor outcrop and deep weathering, but with due effort, far from unattainable.

Martyn, J. E.↗
NASA NTRS1986

New insights into typical Archaean structures in greenstone terranes of western Ontario

Ongoing detailed field work in selected granitoid complexes of the western Wabigoon and Wawa Subprovinces, southern Canadian Shield, has led to several new conclusions: (1) Prominent gneiss domes are composed of prestrained tonalite-granodiorite and represent dense hoods of magmatic granitoid diapirs; (2) the deformation history of the prestrained gneiss remains to be unraveled; (3) the gneiss lacked a thick cover of mafic metavolcanics or other dense rocks at the time of magmatic diaprisim; (4) the synclinoral structure of large greenstone belts is older than the late gneiss domes and may have been initiated by volcano-tectonic processes; (5) small greenstone masses within the gneiss are complexly deformed, together with the gneiss; and, (6) no compelling evidence has been found of ductile early thrusting in the gneiss terranes. Zones of greenstone enclaves occur in hornblende-rich contaminated tonalite and are apt to be deformed magmatic septa. Elsewhere, the tonalite gneiss is biotite-rich and hornblende-poor. These conclusions rest on several new pieces of structural evidence; (1) oval plutons of syenite-diorite have magmatic strain fabrics and sharp contacts that are parallel to an axial-plane foliation in the surrounding refolded gneiss; (2) gneiss domes are lithologically composite and contain large sheath-like structures which are deformed early plutons, distorted earlier gneiss domes, or early ductile nappes produced by folding of planar plutonic septa, and (3) the predomal attitudes of gneissosity varied from point to point.

Schwerdtner, W. M.↗
NASA NTRS1986

The western Wabigoon Subprovince, Superior Province, Canada: Archean greenstone succession in rifted basement complex

The Wabigoon Subprovince, interposed between the predominantly metasedimentary-plutonic and gneissic English River and Quetico Subprovinces to the north and south respectively, exposed Archean greenstone and granitoid rocks for a strike length of greater than 700 km. Based on predominating rock types, the western part of the subprovince is divided into two terrains: the northern Wabigoon volcano-sedimentary and pluonic terrain (NWW) and the Wabigoon Diapiric Axis terrain (WDA). Both the NWW and WDA are described according to volcanic sequence, geological faults, chemical composition and evolutionary history.

Edwards, G. R.↗
NASA NTRS1985

PN velocity beneath Western New Mexico and Eastern Arizona

The experiment involved observing Pn arrivals on an areal array of 7 seismic stations located in the transition zone and along the Jemez lineament. Explosions in coal and copper mines in New Mexico and Arizona were used as energy sources as well as military detonations at White Sands Missile Range, New Mexico, Yuma, Arizona, and the Nevada Test Site. Very preliminary results suggest a Pn velocity of 7.94 km/s (with a fairly large uncertainty) beneath the study area. The Pn delay times, which can be converted to estimates of crustal thickness given knowledge of the velocity structure of the crust increase both to the north and east of Springerville, Arizona. As a constraint on the velocity of Pn, researchers analyzed the reversed refraction line GNOME-HARDHAT which passes through Springerville oriented NW to SE. This analysis resulted in a Pn velocity of 7.9-8.0 km/s for the transition zone. These preliminary results suggest that a normal Pn velocity might persist even though the crust thins (from north to south) by 15 km along the length of the Arizona-New Mexico border. If the upper mantle is currently hot anywhere in western New Mexico or eastern Arizona then the dimensions of the heat source (or sources) might be small compared to the intra-station distances of the seismic arrays used to estimate the velocity of Pn.

Jaksha, L. H.↗
NASA NTRS1985

Microbial mats and modern stromatolites in Shark Bay, Western Australia

Distribution, external morphology, texture, and microbial composition of microbial mats in Hamelin Pool, Shark Bay, Western Australia, have been studied and reviewed along a composite representative profile starting from the permanently submerged zone, across the zones of periodic flooding, toward permanently emerged land and coastal dunes. The following nine types of algal mats have been recognized: colloform, gelatinous, smooth, pincushion, tufted, mamillate, film, reticulate, and blister. Solar ponds represent a particular environment. The mat types represent microbial communities that are characterized by one or more dominant microorganisms. The colonization and stabilization of loose sediment is carried out by a microbial assemblage of generalists that prepare the ground for later replacement and succession by specialized microflora. Lithification of microbial mats takes place periodically, mainly during the austral summer. This process is destructive for the microbial community but increases the preservation potential of the stromatolitic structures.

Golubic, S.↗
NASA NTRS1987

The structure and evolution of seasonal wind anomalies over the near-equatorial eastern Indian and western Pacific Oceans

The longitude-height-time structure and evolution of near-equatorial wind variability over the eastern Indian and western Pacific Oceans are studied using data obtained from a network of eight radiosonde stations extending from southern India to the central Pacific Ocean. The seasonal zonal wind anomalies observed at the cross section beween Trivandrum and Majuro stations are analyzed using an empirical orthogonal function. The Walker Circulation fluctuations are described in terms of standing oscillations in the longitude-height plane, and it is determined that Southern Oscillation propagation anomaly best represents the wind fluctuations. A complex empirical orthogonal function (CEOF) analysis and an El Nino compositing methodology are applied to the seasonal zonal wind anomalies. It is determined that the composite El Nino anomalies correspond to the spatial structure and temporal evolution of anomalies implied by the CEOF analysis.

Gutzler, David S.↗
NASA NTRS1987

Vector constraints on western U.S. deformation from space geodesy, neotectonics, and plate motions

The rate-of-slip vector on the San Andreas fault in central California estimated from geodetic and Holocene geological data is inconsistent with the prediction of rigid plate models such as RM2. This well-known 'San Andreas discrepancy' is diagnostic of plate deformation distributed both east of the fault in the Basin and Range and west of the fault along the California continental margin. Constraints on the integrated deformation rates across these two regions consistent with: (1) the kinematical boundary conditions imposed by the rigid plate model; (2) neotectonic and paleoseismic estimates of deformation rates; (3) ground-based geodetic measurements; and (4) rates of change observed by very long baseline interferometry along seven baselines to western U.S. sites are constructed. The space-geodetic data on Basin and Range extension taken over a 4-year interval are compatible with geological observations averaged over the Holocene; the best estimate of its integrated deformation rate, provided by the joint inversion of both data types, is 9.7 + or - 2.1 mm/yr, N 56 deg W + or - 10 deg, too small and in the wrong direction to account entirely for the San Andreas discrepancy. The integral of this deformation, estimated by subtracting the Basin and Range contribution from the discrepancy vector, requires significant right-lateral shear parallel to the San Andreas (13 + or - 5 mm/yr) and some compression perpendicular to it (9 + or - 3 mm/yr).

Minster, J. Bernard↗
NASA NTRS1987

Regional linear cross-strike discontinuities in Western Aphrodite Terra, Venus

Western Aphrodite Terra, Venus, is characterized by a series of parallel linear structural discontinuities 2000-4000 km in length and 100-200 km wide, which strike at high angles to the general topographic trend of the highlands. The detailed characteristics of these features are similar to terrestrial oceanic fracture zones and strike-slip fault zones. Either interpretation implies the presence of large-scale horizontal tectonic movement on Venus.

Crumpler, L. S.↗
NASA NTRS1988

Western aeronautical test range real-time graphics software package MAGIC

The master graphics interactive console (MAGIC) software package used on the Western Aeronautical Test Range (WATR) of the NASA Ames Research Center is described. MAGIC is a resident real-time research tool available to flight researchers-scientists in the NASA mission control centers of the WATR at the Dryden Flight Research Facility at Edwards, California. The hardware configuration and capabilities of the real-time software package are also discussed.

Malone, Jacqueline C.↗
NASA NTRS1987

A high-resolution local network study of the Nazca plate Wadati-Benioff zone under western Argentina

Seismic data, recorded by INPRES telemetered network located above one of the subhorizontal segments of the subducted Nazca plate Wadati-Benioff zone beneath western Argentina, were analyzed to determine the zone's fine structure. The depth of the center and the thickness of the subhorizontal Wadati-Benioff zone beneath the network were calculated to be about 107 km and about 20 km, respectively, with most of the seismogenic zone concentrated in a region about 12 km thick. The Nazca plate is interpreted to be in a state of down-dip tension and to be decoupled from the overriding South American plate by a weak zone of asthenospheric or shear-heated material. The South American plate is estimated to be 80 km thick, based on the location of the subducted Nazca plate and an inferred decoupling zone between the plates.

Smalley, Robert F., Jr.↗