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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Stratigraphic correlation of the radar-detected subsurface interface in Mare Crisium

The delineation of spectrally distinct units in Mare Crisium allows a more complete interpretation of the single subsurface interface detected by the Apollo lunar sounder experiment. This interface is approximately 1400 m below the surface in the central mare region of Crisium, and 1000 m below the surface in the eastern bench region. Based on the power of the returned signal, and the small difference in dielectric constant of returned lunar basalts, it is probable that this interface represents a buried regolith between two major basin-filling episodes. The contact between spectral Units 1 and 2 is the most likely cause for the radar-reflecting interface. Based on this model, the thickness of Unit 3 is 400 m in the eartern part of the mare, and that of Unit 2 is 1000 m. Estimates of the original depth/diameter relations of Pierce are consistent with excavation of an older basalt from below a depth of 1400 m.

Maxwell, T. A.↗
NASA NTRS1979

Environmental performance evaluation of an advanced-design solid-state television camera

The development of an advanced-design black-and-white solid-state television camera which can survive exposure to space environmental conditions was undertaken. A 380 x 488 element buried-channel CCD is utilized as the image sensor to ensure compatibility with 525-line transmission and display equipment. Specific camera design approaches selected for study and analysis included: (1) component and circuit sensitivity to temperature; (2) circuit board thermal and mechanical design; and (3) CCD temperature control. Preferred approaches were determined and integrated into the final design for two deliverable solid-state TV cameras. One of these cameras was subjected to environmental tests to determine stress limits for exposure to vibration, shock, acceleration, and temperature-vacuum conditions. These tests indicate performance at the design goal limits can be achieved for most of the specified conditions.

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NASA NTRS1979

Field Measurements of Penetrator Seismic Coupling in Sediments and Volcanic Rocks

Field experiments were conducted to determine how well a seismometer installed using a penetrator would be coupled to the ground. A dry-lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were at various distances to generate seismic signals. These signals were detected by the penetrator-mounted geophone assembly and by a reference geophone assembly buried or anchored to surface rock and 1-m from the penetrator. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence, and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology.

Nakamura, Y.↗
NASA NTRS1979

Thickness of western mare basalts

An isopach map of the basalt thickness in the western mare basins is constructed from measurements of the exposed external rim height of partially buried craters. The data, although numerically sparse, is sufficiently distributed to yield gross thickness variations. The average basalt thickness in Oceanus Procellarum and adjacent regions is 400 m with local lenses in excess of 1500 m in the circular maria. The total volume of basalt in the western maria is estimated to be in the range of 1.5 x 10 to the 6th power cu km. The chief distinction between the eastern and western maria appears to be one of basalt volumes erupted to the surface. Maximum volumes of basalt are deposited west of the central highlands and flood subjacent terrain to a greater extent than on the east. The surface structures of the western maria reflect the probability of a greater degree of isostatic response to a larger surface loading by the greater accumulation of mare basalt.

Dehon, R. A.↗
NASA NTRS1978

Global exchange of water vapor on Mars

Observations of the global distribution and seasonal variation of the Martian atmospheric water vapor have been made from the Viking orbiters for a continuous period covering more than half of a Martian year. The seasonal dependence of the latitude distribution of the column abundance of vapor is consistent with a model in which the vapor is in equilibrium with the regolith at polar and middle latitudes. The results indicate the existence of a permanent reservoir of water ice buried at a depth of 10 cm to 1 meter at all latitudes poleward of 40 deg. The behavior of the vapor in the summer hemisphere suggests an annual net transport of the vapor phase from the southern to the northern hemisphere, with deposition of ice of thickness on the order of a few milligrams per sq cm at northern polar latitudes. The hemispheric asymmetry is the result of the propagation of global dust storms originating in the south.

Farmer, C. B.↗
NASA NTRS1978

Radar monitoring of surface and internal glacial flow and iceberg movement

The paper is concerned with the monitoring of glaciers, icebergs, and ice shelves by the use of synthetic aperture radar, buried electromagnetic transponders, and surface data collection platforms. Procedures for determining surface and internal glacial flow vectors and for tracking individual icebergs are described. The design, emplacement, and discrimination of radar targets are considered.

Drake, B.↗
NASA NTRS1979

Formation of Martian flood features by release of water from confined aquifers

It is proposed that the rapid release of water under great pressure from deeply buried aquifers is responsible for the formation of the Martian channels suggestive of catastrophic flooding (outflow channels). Fine channels in the Martian surface suggest the presence of surface water early in the history of the planet, which would have entered the ground water system through the porous near-surface rocks. Subsequent global cooling would have trapped the ground water under a thick permafrost layer and formed a system of confined aquifers. High pore pressures within the aquifers are considered to have triggered the breakout of water from the aquifers at rates of from 10 to the 5th to 10 to the 7th cu m/sec, which would be prevented from reentering the ground water system by the layer of permafrost. Outflow from the aquifer is also considered to have caused the undermining of adjacent areas and the collapse of the surface to form areas of chaos, often associated with channels.

Carr, M. H.↗
NASA NTRS1979

Transonic flow past a symmetrical airfoil at high angle of attack

The results of an experimental investigation of shock-induced stall and leading-edge stall on a 64A010 airfoil section are presented. Advanced nonintrusive techniques - laser velocimetry, holographic interferometry, and buried-wire anemometry - were used in characterizing the inviscid and viscous flow regions. The measurements include Mach contours of the inviscid flow regions, and mean velocity, flow direction and Reynolds shear stress profiles in the separated regions. The experimental observations of this study are relevant to efforts to improve surface pressure prediction methods for airfoils at or near stall.

Johnson, D. A.↗
NASA NTRS1980

Solar heating system installed at Blakedale Professional Center, Greenwood, South Carolina

Information on the solar heating system installed at the Blakedale Professional Center, in Greenwood, South Carolina is presented. The information consists of site and building description, solar system description, performance evaluation, system problems and installation drawings. The solar system was designed to provide approximately 85 percent of the building's heating requirements. The system was installed concurrently with building construction and heats 4,440 square feet of the building. There are 954 square feet of liquid flat plate collectors that are proof-mounted and have a drain-down system to protect the collectors from freezing. A 5,000 gallon steel, polyurethane insulated tank buried underground provides storage. The system was fully instrumented for performance evaluation and integrated into the National Solar Data Network.

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NASA NTRS1979

Induced electric currents in the Alaska oil pipeline measured by gradient, fluxgate, and SQUID magnetometers

The field gradient method for observing the electric currents in the Alaska pipeline provided consistent values for both the fluxgate and SQUID method of observation. These currents were linearly related to the regularly measured electric and magnetic field changes. Determinations of pipeline current were consistent with values obtained by a direct connection, current shunt technique at a pipeline site about 9.6 km away. The gradient method has the distinct advantage of portability and buried- pipe capability. Field gradients due to the pipe magnetization, geological features, or ionospheric source currents do not seem to contribute a measurable error to such pipe current determination. The SQUID gradiometer is inherently sensitive enough to detect very small currents in a linear conductor at 10 meters, or conversely, to detect small currents of one amphere or more at relatively great distances. It is fairly straightforward to achieve imbalance less than one part in ten thousand, and with extreme care, one part in one million or better.

Campbell, W. H.↗
NASA NTRS1980

Solar heating and hot water system installed at Saint Louis, Missouri

The solar heating and hot water system installed at the William Tao & Associates, Inc., office building in St. Louis, Missouri is described, including maintenance and construction problems, final drawings, system requirements, and manufacturer's component data. The solar system was designed to provide 50 percent of the hot water requirements and 45 percent of the space heating needs for a 900 sq ft office space and drafting room. The solar facility has 252 sq ft of glass tube concentrator collectors and a 1000 gallon steel storage tank buried below a concrete slab floor. Freeze protection is provided by a propylene glycol/water mixture in the collector loop. The collectors are roof mounted on a variable tilt array which is adjusted seasonally and is connected to the solar thermal storage tank by a tube-in-shell heat exchanger. Incoming city water is preheated through the solar energy thermal storage tank.

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NASA NTRS1980

New PbSnTe heterojunction laser diode structures with improved performance

Several recent advances in the state-of-the-art of lead tin telluride double heterojunction laser diodes are summarized. Continuous Wave operation to 120 K and pulsed operation to 166 K with single, lowest order transverse mode emission to in excess of four times threshold at 80 K were achieved in buried stripe lasers fabricated by liquid phase epitaxy in the lattice-matched system, lead-tin telluride-lead telluride selenide. At the same time, liquid phase epitaxy was used to produce PbSnTe distributed feedback lasers with much broader continuous single mode tuning ranges than are available from Fabry-Perot lasers. The physics and philosophy behind these advances is as important as the structures and performance of the specific devices embodying the advances, particularly since structures are continually being evolved and the performance continues to be improved.

Fonstad, C. G.↗
NASA NTRS1979

High temperature thermal energy storage in steel and sand

The technical and economic potential for high temperature (343 C, 650 F) thermal energy storage in hollow steel ingots, pipes embedded in concrete, and for pipes buried in sand was evaluated. Because it was determined that concrete would separate from pipes due to thermal stresses, concrete was replaced by sand, which is free from thermal stresses. Variations of the steel ingot concept were not cost effective compared to the sand-pipe approach, therefore, the sand-pipe thermal storage unit (TSU) was evaluated in depth to assess the approximate tube spacing requirements consistent with different system performance characteristics and also attendant system costs. For large TSUs which do not require fast response times, the sand-pipe approach offers attractive possibilities. A pipe diameter about 9 cm (3.5 in) and pipe spacing of approximately 25 cm (10 in), with sand filling the interspaces, appears appropriate. Such a TSU system designed for 8 hours charge/discharge cycle has an energy unit storage cost (CE) of $2.63/kWhr-t and a power unit storage cost (Cp) of $42/kW-t (in 1977 dollars).

Turner, R. H.↗
NASA NTRS1979

Irradiation stratigraphy and depositional history of the Apollo 16 double drive tube 60009/10

We report track density frequency distributions, the fraction of high density grains and minimum track densities for 63, 1 mm wide locations in the Apollo 16 double drive tube 60009/10. From these data we conclude that there are seven irradiation strata in the core. Only one buried reworking zone extending from 50-52 cm was found and it was exposed near the surface from 4.5-9 times 10 to the 6th y with a most probable exposure period of 6 times 10 to the 6th y. There is lack of conclusive data that this zone represents a reworking zone in which case the material below 52 cm most probably was exposed in situ for 4.5 times 10 to the 6th y and developed a reworking zone approximately less than 0.5 cm. The present surface of the core has a reworking zone of 12-13 cm which was exposed from 1.3 times 10 to the 7th to 2.5 times 10 to the 8th y. The best estimate for this exposure period remains the value of approximately less than 1.25 times 10 to the 8th y determined by Bogard and Hirsch (1976). The other strata in the core appear to contain mixtures of various soil types and are not related to in situ depositional events.

Blanford, G. E.↗
NASA NTRS1979

Are early magnesium-rich basalts widespread on the moon

Orbital X-ray data indicate that high-magnesium material systematically occurs along mare/terra boundaries in all the lunar nearside basins for which there is orbital X-ray coverage. These peripheral units appear to represent the earliest stages of volcanism within each of the basins, although they were not necessarily emplaced at the same time in lunar history. High-magnesium subsurface layers excavated by post-mare impact craters in central Mare Crisium and Mare Fecunditatis suggest that the peripheral units are the only visible edges of a basin-wide basalt layer, largely buried by younger less-magnesian flows. This evidence suggests that early magnesium-rich mare basalts are widespread on the moon and that their volumes may be greatly underestimated. Abundant early mare deposits of this type would place severe constraints on models of mare basalt petrogenesis.

Andre, C. G.↗
NASA NTRS1979

The history of an atmosphere of impact origin

Most of the masses accreting onto the earth and terrestrial planets impacted at sufficiently high velocities to release their volatiles into the atmosphere by impact-heating. However, based on models of planetary growth by accumulation from solid bodies, the time-scale for accretion was sufficiently long that the average surface temperatures could not have risen above 320 K. Using measured reaction rates, the released volatiles should have been re-incorporated into the planet by hydrating the surface minerals and were subsequently buried during accretion. Rapid hydration of impact products precludes the formation of a thick atmosphere as the planet accreted. Thus, only the subsequent differentiation and evolution of the terrestrial planets determined the size and composition of each planet's atmosphere.

Jakosky, B. M.↗
NASA NTRS1979

Evidence for ancient mare volcanism

The results of the present study suggest that dark-haloed impact craters are indicative of excavated mafic materials, originally emplaced as volcanic units, but subsequently buried by impact ejecta deposits from large craters and basins. Consequently, mapped light plains units should be viewed as soil units that may not reflect the origin of the underlying rock. Some observations which support these conclusions are examined.

Schultz, P. H.↗
NASA NTRS1980

The contribution of cometary volatiles to the primitive earth

It has been estimated that during its early history the earth captured a mass of cometary material of the order of 10 to the 23rd grams. Since carbon is supposed to be at least three times more abundant in comets than in carbonaceous chondrites (3.5 percent C in C 1 chondrites), it can be deduced that about 1 x 10 to the 22nd grams of carbon (as carbon compounds), were added by comets to the surface of the prebiotic earth. This carbon value is of the same order of magnitude as the value of the organic carbon buried in the earth's sedimentary shell, but approximately one order of magnitude lower than the earth's surface total carbon (7 x 10 to the 22nd gm). The capture of comets by the earth would also have contributed to generating the appropriate aqueous and reducing environmental conditions necessary for organic synthesis.

Oro, J.↗