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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Nuclear Analysis

Exploratory calculations were performed for several gas core breeder reactor configurations. The computational method involved the use of the MACH-1 one dimensional diffusion theory code and the THERMOS integral transport theory code for thermal cross sections. Computations were performed to analyze thermal breeder concepts and nonbreeder concepts. Analysis of breeders was restricted to the (U-233)-Th breeding cycle, and computations were performed to examine a range of parameters. These parameters include U-233 to hydrogen atom ratio in the gaseous cavity, carbon to thorium atom ratio in the breeding blanket, cavity size, and blanket size.

Clement, J. D.↗
NASA NTRS1973

Ultraviolet photometry from the Orbiting Astronomical Observatory. VII alpha squared Canum Venaticorum.

Far-ultraviolet photometry by OAO-2 is presented for alpha squared CVn covering the entire 5.47-day period of this magnetic Ap variable. The light curves ranging from 1330 to 3320 A indicate that there are two important sources of back warming from far-ultraviolet absorption. Strong line blanketing by the rare earths redistributes flux longward of the Balmer discontinuity, causing the major observed photometric variations. In addition, a second source, which may be due to a combination of continuous opacities and line blanketing from the iron-peak and rare-earth groups below 1600 A, apparently redistributes flux into the region of the Balmer discontinuity. It is also found that ground-based determinations of the effective temperature are overestimated due to the flux redistribution from far-ultraviolet absorption. The effective temperature of alpha squared CVn derived from OAO and ground-based absolute fluxes is found to be 11,200 K, which remains constant over the cycle.

Molnar, M. R.↗
NASA NTRS1973

Lunar magnetic anomalies and the Cayley formation

It is proposed that magnetic anomalies such as found at the Apollo 16 site are associated with breccia flows which cooled in place from above 770 C. The required field at the time that this process took place is a few thousand gamma. It is suggested that the surface and orbital magnetic anomalies are caused by basins filled with Cayley-like breccia flows to a thickness of the order of a kilometer. These breccia blankets settled in place from temperatures above 770 C and a thickness on the order of 1 km was welded to a level of 2 to 4 on Warner's scale. A base surge caused by impact or by a volcanic event could be the mechanism by which these breccia blankets were deposited.

Strangway, D. W.↗
NASA NTRS1974

Predicting spacecraft multilayer insulation performance from heat transfer measurements

Multilayer insulation (MLI) ideally consists of a series of radiation shields with low-conductivity spacers. When MLI blankets were installed on cryogenic tanks or spacecraft, a large discrepancy between the calorimeter measurements and the performance of the installed blankets was discovered. It was found that discontinuities such as exposed edges coupled with high lateral heat transfer created 'heat leaks' which overshadowed the basic heat transfer of the insulation. Approaches leading to improved performance predictions of MLI units are discussed.

Stimpson, L. D.↗
NASA NTRS1974

Lunar basin formation and highland stratigraphy

Multiring impact basins, formed after solidification of the lunar crust, account for most or all premare regional deposits and structures expressed in the lunar landscape and for major topographic and gravity variations. A fresh basin has two or more concentric mountain rings, a lineated ejecta blanket, and secondary impact craters. Crackled material on the floor may be impact melt. The ejecta blanket was emplaced at least partly as a ground-hugging flow and was probably hot. A suggested model of basin formation is that the center lifts up and the rings form by inward collapse during evisceration. The resulting basin is shallow and has a central uplift of the mantle. This results in a central gravity high and a ring low. Later flooding by mare basalt has since modified most near side basins. Highland deposits of plains, furrowed and pitted terrain, and various hills, domes, and craters that were interpreted before the Apollo missions as being volcanic can now be interpreted as being basin related.

Howard, K. A.↗
NASA NTRS1975

Design and fabrication of a flexible tunnel for Sortie Laboratory

A program was conducted to update a prototype design and to fabricate a flexible tunnel for a space shuttle/spacelab interface structure. The significant changes in the prototype are as follows: (1) elimination of foam from bladder laminate to increase bladder flexibility, (2) heat treat pulley brackets, bolts, and hinge pin to 160,000 psi minimum tensile strength, and (3) reduction of the meteoroid barrier from 0.5 inch to 0.375 inch. The thermal blanket installation study resulted in developing a method of installation by properly folding the various layers so that a uniform thickness could be maintained under the clamps. A single-lobe mockup was fabricated and cycled open and closed several times with no apparent damage to the blanket.

Source record↗
NASA NTRS1975

The life and times of Big Bertha - Lunar breccia 14321

The assembly and metamorphic history of polymict breccia 14321 are reconstructed. The earliest formed fragmental component of 14321 (microbreccia-1) is dominated by KREEP-rich norite, extruded and subsequently brecciated and lithified in an ejecta blanket at approximately 1000 C in the general region of Mare Imbrium after the Serenitatis impact but prior to the Imbrium impact. This early microbreccia component and lesser amounts of mare-type basalt, microgranite, rhyolite glass, anorthosite and olivine microbreccia were assembled at the Apollo 14 site as part of the Fra Mauro ejecta blanket from the Imbrium impact. The resulting microbreccia-3 incorporates all the lithic types above and accretionary lapilli structures (microbreccia-2) in a dark matrix annealed at approximately 700 C. A later impact on the Fra Mauro excavated and mutually abraded microbreccia-3 and a local, 14321-type, basalt which were assembled into polymict breccia 14321. Final placement of 14321 at its sampling location was accomplished during the minor Cone Crater impact event.

Duncan, A. R.↗
NASA NTRS1975

Evaluation of low cost/high temperature insulation, July 1974 - June 1975

Six fiber products and six insulation blankets comprising silica, alumina, zirconia, mullite, and mixed ceramic systems were subjected to furnace exposures up to 500 hours at temperatures of 1000 to 1600 C and evaluated for chemical and dimensional stability and for changes in thermal conductivity. Alumina, zirconia, and mullite fibers were fabricated into reusable surface insulation (RSI) tile by water-felting and reimpregnation with ethyl silicate. Specimens were exposed to 25 thermal cycles at 1200 C and 1400 C and a pressure of 10 and 32 torr, respectively. Production costs for 930 sq m (10,000 sq ft) of blanket insulation and of alumina RSI tile were developed.

Strauss, E. L.↗
NASA NTRS1976

Thermal performance of a customized multilayer insulation (MLI)

The thermal performance of a LH2 tank on a shroudless vehicle was investigated. The 1.52 m (60 in) tank was insulated with 2 MLI blankets consisting of 18 double aluminized Mylar radiation shields and 19 silk net spacers. The temperature of outer space was simulated by using a cryoshroud which was maintained at near liquid hydrogen temperature. The heating effects of a payload were simulated by utilizing a thermal payload simulator (TPS) viewing the tank. The test program consisted of three major test categories: (1) null testing, (2) thermal performance testing of the tank installed MLI system, and (3) thermal testing of a customized MLI configuration. TPS surface temperatures during the null test were maintained at near hydrogen temperature and during test categories 2 and 3 at 289 K (520R). The heat flow rate through the tank installed MLI at a tank/TPS spacing of 0.457 m was 1.204 watts with no MLI on the TPS and 0.059 watts through the customized MLI with three blankets on the TPS. Reducing the tank/TPS spacing from 0.457 m to 0.152 m the heat flow through the customized MLI increased by 10 percent.

Leonhard, K. E.↗
NASA NTRS1976

Testing of typical spacecraft materials in a simulated substorm environment

An investigation to determine spacecraft materials characteristics under charging conditions was conducted at the Lewis Research Center substorm simulation facility. The test specimens were spacecraft paints, silvered Teflon, thermal blankets and solar array segments. The samples, ranging in size from 300 to 1,000 sq cm were exposed to monoenergetic electron energies from 2 to 20 keV at a current density of 1 nA sq cm. The samples generally behaved as capacitors with strong voltage gradients at their edges. The charging characteristics of the silvered Teflon, Kapton, and solar cell covers were controlled by the secondary emission characteristics. Insulators that did not discharge were the spacecraft paints and the quartz fiber cloth thermal blanket sample. All other samples did experience discharges when the surface voltage reached -8 to -16 kV. The discharges were photographed. The breakdown voltage for each sample was determined and the average energy lost in the discharge was computed.

Stephens, N. J.↗
NASA NTRS1976

High-explosive cratering analogs for bowl-shaped, central uplift, and multiring impact craters

The paper describes six experimental explosion craters in terms of their basic morphology, subsurface structural deformation, and surrounding ejecta blanket. These craters exhibit one or more of the following features: bowl shapes with underlying breccia lens, central uplifts, multirings, terraced walls, rim strata, zones of concentric rim deformation, inner continuous ground cover of ejecta blankets formed by overturned flaps, secondary cratering, and fused alluvium. These craters were formed by large shock wave energy transfers at or near zero heights-of-burst, and it is possible that impact craters with analogous morphologic and structural features may have formed under similar surface energy transfer conditions.

Roddy, D. J.↗
NASA NTRS1977

Testing of typical spacecraft materials in a simulated substorm environment

The test specimens were spacecraft paints, silvered Teflon, thermal blankets, and solar array segments. The samples, ranging in size from 300 to 1000 sq cm were exposed to monoenergetic electron energies from 2 to 20 keV at a current density of 1 NA/sq cm. The samples generally behaved as capacitors with strong voltage gradient at their edges. The charging characteristics of the silvered Teflon, Kapton, and solar cell covers were controlled by the secondary emission characteristics. Insulators that did not discharge were the spacecraft paints and the quartz fiber cloth thermal blanket sample. All other samples did experience discharges when the surface voltage reached -8 to -16kV. The discharges were photographed. The breakdown voltage for each sample was determined and the average energy lost in the discharge was computed.

Stevens, N. J.↗
NASA NTRS1978

Design and fabrication of a radiative actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

The panel assembly consisted of an external thermal protection system (metallic heat shields and insulation blankets) and an aluminum honeycomb structure. The structure was cooled to temperature 442K (300 F) by circulating a 60/40 mass solution of ethylene glycol and water through dee shaped coolant tubes nested in the honeycomb and adhesively bonded to the outer skin. Rene'41 heat shields were designed to sustain 5000 cycles of a uniform pressure of + or - 6.89kPa (+ or - 1.0 psi) and aerodynamic heating conditions equivalent to 136 kW sq m (12 Btu sq ft sec) to a 422K (300 F) surface temperature. High temperature flexible insulation blankets were encased in stainless steel foil to protect them from moisture and other potential contaminates. The aluminum actively cooled honeycomb sandwich structural panel was designed to sustain 5000 cycles of cyclic in-plane loading of + or - 210 kN/m (+ or - 1200 lbf/in.) combined with a uniform panel pressure of + or - 6.89 kPa (?1.0 psi).

Ellis, D. A.↗
NASA NTRS1978

Thermal performance of gaseous-helium-purged tank-mounted multilayer insulation system during ground-hold and space-hold thermal cycling and exposure to water vapor

An experimental investigation was conducted to determine (1) the ground-hold and space-hold thermal performance of a multilayer insulation (MLI) system mounted on a spherical, liquid-hydrogen propellant tank and (2) the degradation to the space-hold thermal performance of the insulation system that resulted from both thermal cycling and exposure to moisture. The propellant tank had a diameter of 1.39 meters (4.57ft). The MLI consisted of two blankets of insulation; each blanket contained 15 double-aluminized Mylar radiation shields separated by double silk net spacers. Nineteen tests simulating basic cryogenic spacecraft thermal (environmental) conditions were conducted. These tests typically included initial helium purge, liquid-hydrogen fill and ground-hold, ascent, space-hold, and repressurization. No significant degradation of the space-hold thermal performance due to thermal cycling was noted.

Sumner, I. E.↗
NASA NTRS1978

Alteration of glass as a possible source of clay minerals on Mars

Thermodynamic calculations show that, under present Martian surface conditions, favorable gas-solid weathering products of feldspar glasses should include beidellites (clays of the montmorillonite series) + carbonates + quartz. The gas-solid weathering of mafic silicate glass ( of volcanic or impact origin) may similarly favor the production of metastable Fe-rich montmorillonite clays. Simple mass-balance calculations suggest that gas-solid weathering of Martian proto-regolith containing 10% glass could conceivably produce a global blanket of clays at a rate of at least 0.4 cm/b.y. The production rate should be expected to increase significantly with the glass content and rate of reworking of the proto-regolith and with the availability of water. Complete extraction of altered glass from a lunar-like proto-regolith might yield a global Martian clay blanket about 10-100 cm in thickness.

Gooding, J. L.↗
NASA NTRS1978

Phobos - Photometry and origin of dark markings on crater floors

Viking Orbiter 1 close encounter pictures of Phobos reveal unusual dark patches on the floors of many craters. Photometry of these features indicates that they have a similar normal reflectance but a phase coefficient 30% larger than the average surface. These facts suggest that the 'dark' material has a similar composition but a much rougher texture than the average surface of Phobos. By analogy with terrestrial impact, explosion and laboratory craters, the dark patches are interpreted as impact generated melt pools which remain visible on Phobos due to the low value of g and consequent small amount of fallback ejecta and slumping. Since blanketing by ejecta from subsequent impacts and micrometeoroid erosion should eventually obliterate such features, they should be more conspicuous in the fresher craters. Similar features should be visible on small asteroids and other low g bodies. However, they are not prominent on the surface of Deimos - possibly because most of the craters imaged at high resolution on the outer satellite appear to have been blanketed by several meters of fine-grained material.

Goguen, J.↗
NASA NTRS1978

Ultra-low-mass flexible planar solar arrays using 50-micron-thick solar cells

A conceptual design study has been completed which has shown the feasibility of ultra-low-mass planar solar arrays with specific power of 200 watts/kilogram. The beginning of life (BOL) power output of the array designs would be 10 kW at 1 astronomical unit (AU) and a 55C deg operating temperature. Two designs were studied: a retractable rollout design and a non-retractable fold-out. The designs employed a flexible low-mass blanket and low-mass structures. The blanket utilized 2 x 2 cm high-efficiency (13.5% at 28C deg AM0), ultra-thin (50 micron), silicon solar cells protected by thin (75 micron) plastic encapsulants. The structural design utilized the 'V'-stiffened approach which allows a lower mass boom to be used. In conjunction with the conceptual design, modules using the thin cells and plastic encapsulant were designed and fabricated.

Costogue, E. N.↗
NASA NTRS1979

SEP solar array development testing

This paper describes the test program of a lightweight 25 kW solar array for solar electric propulsion. A full-scale development wing was made of aluminum with the containment box cover of graphite-epoxy, while the flight design array wing uses a graphite-epoxy structure. The full-scale continuous longeron array extension mast was tested for performance on a water table, and the full scale wing was functionally tested to demonstrate automatic containment box unlocking, wing extension, and retraction, blanket tensioning, and automatic application of blanket preload. The wing was then tested to the Shuttle acoustic environment, followed by a thermal/vacuum test in which the wing was extended and retracted at high and low temperature. Finally, the wing was tested in vibration with sine and random vibration environments.

Elms, R. V., Jr.↗