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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Development of a non-cryogenic nitrogen/oxygen supply system

Modular components were refined or replaced to improve the performance of the electrolysis module in a system which generates both oxygen and hydrogen from hydrazine hydrate. Significant mechanical and electrical performance improvements were achieved in the cathode. Improvements were also made in the phase separation area but at considerable cost in time and money and to the detriment of other investigative areas. Only the pump/bubble separator failed in a manner necessitating redesign. Its failure was, however, due to its being operated above the temperature range for which it was designed. The basic electrolysis cell design was not changed.

Source record↗
NASA NTRS1978

Thermal energy storage subsystems. A collection of quarterly reports

The design, development, and progress toward the delivery of three subsystems is discussed. The subsystem used a salt hydrate mixture for thermal energy storage. The program schedules, technical data, and other program activities from October 1, 1976, through December 31, 1977 are presented.

Source record↗
NASA NTRS1978

Infrared observations of asteroids from earth and space

Infrared reflectances at wavelength between 1 and 4 micrometers are used for determining asteroid surface mineralogy, surface composition, diameters, and albedos. Thermal models were developed for analyzing infrared observations at longer wavelengths. The discovery of a spectral feature due to water of hydration on Ceres seems to contradict the mineralogy inferred from spectrophotometry.

Matson, D. L.↗
NASA NTRS1978

Implications of abundant hygroscopic minerals in the Martian regolith

Converging lines of evidence suggest that a significant portion of the Martian surface fines may consist of salts and smectite clays. Salts can form stoichiometric hydrates as well as eutectic solutions with depressed freezing points; clays contain bound water of constitution and adsorb significant quantities of water from the vapor phase. The formation of ice may be suppressed by these minerals in some regions on Mars, and their presence in abundance would imply important consequences for atmospheric and geologic processes and the prospects for exobiology.

Clark, B. C.↗
NASA NTRS1978

The effect of H2O and CO2 on planetary mantles

The peridotite-H2O-CO2 system is discussed, and it is shown that even traces of H2O and CO2, in minerals or vapor, lower mantle solidus temperatures through hundreds of degrees in comparison with the volatile-free solidus. The solidus for peridotite-H2O-CO2 is a divariant surface traversed by univariant lines that locate the intersections of subsolidus divariant surfaces for carbonation or hydration reactions occurring in the presence of H2O-CO2 mixtures. Vapor phase compositions are normally buffered to these lines, and near the buffered curve for the solidus of partly carbonated peridotite there is a temperature maximum on the peridotite-vapor solidus. Characteristics on the CO2 side of the maximum and on the H2O side of the maximum are described.

Wyllie, P. J.↗
NASA NTRS1978

Mars - The role of the regolith in volatile storage and atmospheric evolution

Earth-based observations of the optical properties of Mars, laboratory alteration experiments, Mariner 9 data, and Viking lander observations are reviewed which indicate the existence of hydrated minerals on the Martian surface. The problem of estimating the total inventory of H2O, CO2, and other volatiles that may be stored in the Martian regolith is discussed, and morphological evidence is cited which supports the possible occurrence of hard-frozen permafrost in some areas on Mars. Physical adsorption of CO2 in the Martian regolith is considered, buffering of atmospheric pressure by regolith-atmosphere reequilibration is examined, and the problem of the exceedingly low inventory of Ar-36 in the Martian atmosphere is investigated. The possibility is considered that earth's degassing history may have had a larger component of long-diffusion-path degassing from a large hot body while the Martian surface inventory may have received a proportionately greater contribution from volatization of accreting particles.

Fanale, F. P.↗
NASA NTRS1978

Mars - Near-infrared spectral reflectance and compositional implication

Several distinct absorption features, some recognized for the first time, are evident in a newly obtained reflectance spectrum (wavelengths = 0.62-2.6 microns, reciprocal dispersion = 83) of the integral disk of Mars. The effects of Martian atmospheric CO2 have been removed from the spectrum to arrive at a reflectance spectrum that is believed to be due mostly to surface material. Absorptions, at 1.22, 1.55, and 2.05 microns are interpreted to indicate the presence of H2O ice plus high desiccated mineral hydrate, although an H2O ice phase with strongly shifted fundamental frequencies cannot be ruled out. Ferrosilicate and ferric oxide bands near and shortward of 1.0 micron are confirmed. The new observations were made on April 21-23, 1976, universal time, at the 2.24-m telescope on Mauna Kea, Hawaii, using a newly developed infrared spectrometer.

Mccord, T. B.↗
NASA NTRS1979

Remote spectroscopic identification of carbonaceous chondrite mineralogies Applications to Ceres and Pallas

High-resolution spectroscopic observations of asteroids Ceres and Pallas have been obtained in the 1.0- to 2.6-micron region. Combined with previous spectral measurements at other wavelengths, this work presents the broadband spectral reflectances of these asteroids over the 0.4- to 3.6-micron region. This extended coverage permits new analyses of the surface mineralogies of these objects. Using laboratory comparison spectra of meteorites and mixtures of terrestrial minerals, the surfaces of Ceres and Pallas are consistent with mixtures of opaques and hydrated silicates, such as are found in types C1 and C2 meteorites. This research emphasizes the importance of the 3-micron spectral region for studying by remote methods the relationship of carbonaceous chondrite mineralogies to asteroid surfaces.

Larson, H. P.↗
NASA NTRS1979

Vaporization of comet nuclei - Light curves and life times

The effects of vaporization from the nucleus of a comet are examined and it is shown that a latitude dependence of vaporization can explain the asymmetries in cometary light curves. An attempt is made to explain the observed variation in molecular production rates with heliocentric distance when employing CO2 and clathrate hydrate ice as cometary nuclei substances. The energy balance equation and the vapor pressure equations of water and CO2 are used in calculating the vaporization from a surface. Calculations were carried out from both dry-ice and water-ice nuclei, using a variety of different effective visual albedos, but primarily for a thermal infrared of 0 (emission). Attention is given to cometary lifetimes and light curves and it was determined that the asymmetry in light curves occurs (occasionally) as a 'seasonal' effect due to a variation in the angle between the comet's rotation axis and the sun-comet line.

Cowan, J. J.↗
NASA NTRS1980

Mechanisms of water-salt metabolism disturbances in dogs subjected to six month hypokinesia

Water-salt metabolism in dogs during prolonged restricted motor activity (hypokinesia) was investigated. It was found that hydration occurred and fluid was redistributed between the extra- and intra-cellular sectors. Also, electrolyte excretion rose, and magnetism and calcium metabolism changed significantly. It is concluded that the forces caused by muscle strain proper (which was decreased under conditions of hypokinesia) influence the state of bone metabolism.

Korolkov, V. I.↗
NASA NTRS1979

The radioracemization of isovaline - Cosmochemical implications

The optically pure D- and L-enantiomers of isovaline, which cannot be racemized by ordinary chemical mechanisms involving alpha-hydrogen removal and which has been isolated in apparently racemic form from the Murchison meteorite, have been subjected to partial radiolysis by the ionizing radiation from a 3000-Ci Co-60 gamma-ray source. Both in the anhydrous and hydrated solid states and as solid sodium or hydrochloride salts each enantiomer suffered significant radioracemization of the undestroyed residue during its partial radiolysis. The sodium salt of isovaline in 0.1-M aqueous solution suffered extensive radiolysis with relatively small radiation doses, but showed no detectable radioracemization. The significance of these observations with respect to the primordial enantiomeric composition of the isovaline (and other amino acids) indigenous to meteorites is discussed.

Bonner, W. A.↗
NASA NTRS1979

Mars surface composition from reflectance spectroscopy - A summary

Visible and near-infrared reflectance spectra and multispectral maps of the Martian surface are discussed, and implications of the data for the composition of the Martian surface are considered. Spacecraft and earth-based telescopic observations have confirmed the generally bimodal albedo distribution of the planet, dividing the surface into bright and dark regions. Mars spectra are characterized by the presence of strong Fe(+3) absorption, which is attributed to various ferric oxide minerals. Interpretations of the spectra from the dark regions indicate a basaltic or ultramafic source rock. Evidence for water ice or a highly desiccated metal hydrate has been obtained, along with evidence for CO2-ice only in the south polar cap. Mariner 9 observations of Martian dust suggest the presence of rather acidic rock or mineral particles, or a montmorillonite-type clay. Prospects for the future study of Martian surface composition include continuing earth-based spectrophotometric studies, and high-spectral-resolution mapping of a significant portion of the surface by the Galileo spacecraft and the next Mars mission.

Singer, R. B.↗
NASA NTRS1979

Heterogeneous phase reactions of Martian volatiles with putative regolith minerals

The chemical reactivity of several minerals thought to be present in Martian fines is tested with respect to gases known in the Martian atmosphere. In these experiments, liquid water is excluded from the system, environmental temperatures are maintained below 0 C, and the solar illumination spectrum is stimulated in the visible and UV using a xenon arc lamp. Reactions are detected by mass spectrometric analysis of the gas phase over solid samples. No reactions were detected for Mars nominal gas over sulfates, nitrates, chloride, nontronite clay, or magnetite. Oxidation was not observed for basaltic glass, nontronite, and magnetite. However, experiments incorporating SO2 gas an expected product of volcanism and intrusive volatile release - gave positive results. Displacement of CO2 by SO2 occurred in all four carbonates tested. These reactions are catalyzed by irradiation with the solar simulator. A calcium nitrate hydrate released NO2 in the presence of SO2. These results have implications for the cycling of atmospheric CO2, H2O, and N2 through the regolith.

Clark, B. C.↗
NASA NTRS1980

Physical loss of long-period comets

Loss of long-period comets from the solar system through a variety of physical processes is investigated. It is shown that planetary collision, defined as a comet passing within the Roche radius of any planet, has a probability of 1.35 x 10 to the -7th per perihelion passage for a long-period comet on a randomly oriented orbit. Sublimation of all volatiles for a one-kilometer radius hydrate ice nucleus would require on the order of 600 to 27,600 perihelion passages, depending on the surface albedo and assuming a perihelion distance of one astronomical unit. Analysis of observational records indicates that for dynamically 'new' comets in the Oort-Schmidt sense there is about a 10% probability of the comet randomly disrupting on its first perihelion passage. This probability drops to 4% per perihelion passage for older long-period comets, and less than 1% for short-period comets. The consequences of these loss mechanisms when incorporated into Monte-Carlo studies of long-period comet evolution are also discussed.

Weissman, P. R.↗
NASA NTRS1980

Vaporization in comets - The icy grain halo of Comet West

The variation with heliocentric distance of the production rates of various species in Comet West (1975n = 1976 VI) is explained with a cometary model consisting of a CO2 dominated nucleus plus a halo of icy grains of H2O or clathrate hydrate. It is concluded that the parents of CN and C3 are released primarily from the nucleus but that the parent of C2 is released primarily from the halo of icy grains.

Ahearn, M. F.↗
NASA NTRS1980

Incorporation of metal ions into polyimides

The effects of the incorporation of metal ions into various polyimides on polyimide properties are investigated. Polyimide films derived from 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BDTA) 3,3'-diaminobenzophenone (m,m'-DABP), 4,4'-diaminobenzophenone (p,p'-DABP) or 4,4'-oxydianiline were prepared with the concurrent addition of approximately 20 metals in a variety of forms. In general, it is found that the films derived from BDTA + p,p'-DABP were brittle and of poor quality, with brittle films also produced in most of the BDTA + m, m'-DABP polyimides regardless of whether the added metal was hydrate or anhydrous. Thermomechanical analysis, torsional braid analysis, thermal gravimetric analysis, infrared spectral analysis and isothermal studies on many of the polyimide films produced indicate that the softening temperature is generally increased upon the addition of metal ions, at the expense of thermal stability, while no changes in chemical functionality are observed. The best system studied in regard to polymer property enhancement appears to be tri(acetylacetonato)aluminum(III) added to the m, m'-DABP polyamide, which has been found to exhibit four times the lap shear strength of the polyimide alone.

Taylor, L. T.↗
NASA NTRS1980

Properties of clusters in the gas phase. V - Complexes of neutral molecules onto negative ions

Ion-molecules association reactions of the form A(-)(B)n-1 + B = A(-)(B)n were studied over a range of temperatures in the gas phase using high pressure mass spectrometry. Enthalpy and entropy changes were determined for the stepwise clustering reactions of (1) sulfur dioxide onto Cl(-), I(-), and NO2(-) with n ranging from one to three or four, and onto SO2(-) and SO3(-) with n equal to one; and (2) carbon dioxide onto Cl(-), I(-), NO2(-), CO3(-), and SO3(-) with n equal to one. From these data and earlier hydration results, the order of the magnitude of the enthalpy changes on the association of the first neutral for a series of negative ions was found to parallel the gas-phase basicity of those anions.

Keesee, R. G.↗
NASA NTRS1978

Phase diagram of KHF2 and non-equilibrium effects

The equilibrium diagram for the KHF2-H2O system was constructed from cooling and heating curves for the compositions between 5 wt% and 40 wt% KHF2 and the results are shown. The phase diagrams shown is typical of that of a two component system with miscible liquid phases and whole solid phases consist of pure components. A eutectic point was found at approximately 15% KHF2 which remains completely liquid down to a temperature of -9.0 C. No hydrate formation was observed and no anomalous behavior such as the occurrence of solid transitions or metastable states was observed. The effect of rapid freezing on the equilibrium diagram did not appear, and cooling curves exhibited only one halt. Also, at rapid freezing rates, the supercooling of the solutions was smaller than those observed at the slow cooling rates. The existence of a eutectic composition and the slow rate of dissolution of the salt are used to interpret heat absorption behavior in practical applications of the KHF2-H2O system.

Hobson, M. C.↗