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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Development of an advanced static feed water electrolysis module

A Static Feed Water Electrolysis Module (SFWEM) was developed to produce 0.92 kg/day (2.0 lb/day) of oxygen (O2). Specific objectives of the program's scope were to (1) eliminate the need for feed water cavity degassing, (2) eliminate the need for subsystem condenser/separators, (3) increase current density capability while decreasing electrolysis cell power (i.e., cell voltage) requirements, and (4) eliminate subsystem rotating parts and incorporate control and monitor instrumentation. A six-cell, one-man capacity module having an active area of 0.00929 sq m (0.10 sq ft) per cell was designed, fabricated, assembled, and subjected to 111 days (2664 hr) of parametric and endurance testing. The SFWEM was successfully operated over a current density range of 0 to 1076 mA/sq cm (0 to 1000 ASF), pressures of ambient to 2067 kN/sq m (300 psia), and temperatures of ambient to 366 K (200 F). During a 94-day endurance test, the SFWEM successfully demonstrated operation without the need for feed water compartment degassing.

Schubert, F. H.↗
NASA NTRS1977

Photochemistry and evolution of Mars' atmosphere - A Viking perspective

Viking measurements of the upper atmosphere of Mars have indicated thermospheric temperatures below 200 K, colder than those originally calculated by remote sensing experiments. It is suggested that dynamical coupling of the upper and lower regions of the Martian atmosphere may account for the variability in thermospheric temperature. The absorption of extreme ultraviolet solar radiation may account for observed ionospheric features, and may provide a source of fast N and O atoms escaping the planet's gravitational field. Measurements of the isotopic composition of O and N may be used to place constraints on models of the evolution of the Martian atmosphere. It is suggested that previous abundance of N2 may have exceeded that of CO2 in the present atmosphere, and that large sources of H2O may exist on the planet. The present degassing rate for nitrogen is felt to be less than the time-averaged degassing rate by at least a factor of 20.

Mcelroy, M. B.↗
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 NTRS1979

Ar-40/Ar-39 age of the Shergotty achondrite and implications for its post-shock thermal history

Ar-40/Ar-39 measurements are used to determine the age of the Shergotty achondrite and the chronology of the shock event responsible for the complete conversion of its plagioclase to maskelynite is discussed. Apparent ages are found to vary between 240 and 640 million years for the whole rock sample, with a plateau age of 254 million years for a maskelynite separate. The Rb-Sr age of 165 million years determined by Nyquist at al (1978) suggests that the maskelynite as well as the whole rock was incompletely degassed. Argon diffusion characteristics indicate a post-shock cooling time greater than 1000 years and a burial depth greater than 300 m for a thermal model of a cooling ejecta blanket of variable thickness. It is concluded that the shock event which degassed the argon and reset the Rb-Sr systematics occurred between 165 and 250 million years ago when the parent body experienced a collision in the asteroid belt.

Bogard, D. D.↗
NASA NTRS1980

Ar-40/Ar-39 dating, Ar diffusion properties, and cooling rate determinations of severely shocked chondrites

The ages of Ar-40/Ar-39 chondrites were computed to be 4.29 to 1.0 Gyr, with degassing times of 0.5 to 1.0 Gyr. The values of the diffusion parameter for Ar in Arrhenius plots show linear relationships which correspond to the degassing of different mineral phases with distinct K/Ca ratios and different average temperatures for Ar release. The experimental values of the diffusion parameter for the high-temperature phase of severely shocked chondrites are 10 to the -7th to 10 to the -5th/s for the shock-heating temperatures in the 950-1200 C range; the inferred reheating temperatures and the fraction of the Ar-40 loss during the reheating event suggest post-shock cooling rates and burial depths of 0.01-0.0001 C/s and 0.5-2m, respectively.

Bogard, D. D.↗
NASA NTRS1983

Degassifying and mixing apparatus for liquids

An apparatus for degassing a liquid comprises a containment vessel a liquid pump and a header assembly (12) within the containment vessel in a volume above the reservoir of the liquid. The pump draws from this reservoir and outputs to the header assembly, the latter being constructed to return the liquid to the reservoir in the form of a number of stacked, vertically spaced, concentric, conical cascades via orifices. A vacuum source provides a partial vacuum in the containment vessel to enhance the degassing process.

Yamauchi, S. T.↗
NASA NTRS1986

Fluidization and hydrothermal alteration of the suevite deposit at the Ries Crater, West Germany, and implications for Mars

The emplacement, cooling, and alteration of the suevite at the Ries Crater are discussed. The clay mineralogy of the suevite is examined in terms of the cooling of the suevite and the importance of hydrothermal alteration. It is observed that the suevite contains large number of chimneylike degassing pipes, and that the suevite outside of the crater rim contains about 15 wt pct clay. The vertical channels or degassing pipes related to the fall-out of suevite are described. The relationship between the formation of the impact deposits on earth and Mars and the origin of Martian soil, and the emplacement and alteration of impact ejecta is studied.

Newsom, Horton E.↗
NASA NTRS1988

Evolution of a steam atmosphere during earth's accretion

The evolution of an impact-generated steam atmosphere around an accreting earth is presently modeled under the assumption of Safronov (1978) accretion, in a scheme that encompasses the degassing of planetesimals on impact, thermal blanketing by the steam atmosphere, surface-to-interior water exchange, the shock heating and convective cooling of the earth's interior, and hydrogen escape due both to solar EUV-powered planetary wind and impact erosion. The model yields four distinct classes of impact-generated atmospheres: the first, on which emphasis is placed, has as its salient feature a molten surface that is maintained by the opacity of a massive water vapor atmosphere; the second occurs when the EUV-limited escape exceeds the impact degassing rate, while the third is dominated by impact erosion and the fourth is characterized by an atmosphere more massive than any thus far encountered.

Zahnle, Kevin J.↗
NASA NTRS1987

Absorption of the Martian regolith: Specific surface area and missing CO(sub 2)

For most estimates of available regolith and initial degassed CO(sub 2) inventories, it appears that any initial inventory must have been lost to space or incorporated into carbonates. Most estimates of the total available degassed CO(sub 2) inventory are only marginally sufficient to allow for a major early greenhouse effect. It is suggested that the requirements for greenhouse warming to produce old dessicated terrain would be greatly lessened if groundwater brines rather than rainfall were involved and if a higher internal gradient were involved to raise the water (brine) table, leading to more frequent sapping.

Zent, A. P.↗
NASA NTRS1988

How well do we know the Martian abundances of highly volatile elements

The table is given that summarizes four models based on observations and gives some reasonable inferences of each for Martian volatiles. The table columns give: (1) the volatile assumptions of the model; (2) the inferred Martian volatile concentrations relative to earth; (3) the N/36 Ar and C/36 Ar ratios; (4) the percentage of Martian degassing inferred by the model, and 5 and 6) the equivalent global column heights of liquid water and solid CaCO3 over the entire surface of Mars that would be formed from the model quantities of degassed volatiles.

Bogard, Donald↗
NASA NTRS1989

Coupled evolution of the atmospheres and interiors of planets and satellites

The evolution of a planetary atmosphere can be powerfully influenced by the planetary interior's function as both a source and a sink of atmospheric constituents; the interior can in turn be strongly influenced by the atmosphere because the mechanism of interior heat loss depends on a volatile content for which the atmosphere can serve both as sink and source. The dependence of mantle rheology on volatile content could furnish a feedback mechanism tending to keep regassing/degassing in balance, thereby maintaining a relatively constant atmospheric mass. Consideration of the abundances of radiogenic and nonradiogenic noble gases in the earth's atmosphere, and of the fluxes of these gases from the mantle, support a large degassing event early on, followed by a decrease in degassing efficiency with time and relatively inefficient outgassing over most of geologic time.

Schubert, G.↗
NASA NTRS1989

Hydrogen-isotope evidence for extrusion mechanisms of the Mount St Helens lava dome

Hydrogen isotope analyses were used to determine water content and deuterium content for 18 samples of the Mount St Helens dome dacite in an attempt to identify the triggering mechanisms for periodic dome-building eruptions of lava. These isotope data, the first ever collected from an active lava dome, suggest a steady-state process of magma evolution combining crystallization-induced volatile production in the chamber with three different degassing mechanisms: closed-system volatile loss in the magma chamber, open-system volatile release during ascent, and kinetically controlled degassing upon eruption at the surface. The data suggest the future dome-building eruptions may require a new influx of volatile-rich magma into the chamber.

Anderson, Steven W.↗
NASA NTRS1989

C-O-H ratios of silicate melt inclusions in basalts from the Galapagos Spreading Center near 95 deg W - A laser decrepitation mass spectrometry study

Ratios of C, O, and H dissolved in silicate glass inclusions and pillow rind glasses in samples from the Galapagos Spreading Center near 95 deg W were analyzed (using laser volatilization and mass spectrometry), and the data were assessed in terms of mantle source compositions, oxygen fugacity, kinetic fractionation, and magmatic degassing. It was found that glass inclusions in the Galapagos failing rift lavas are higher and more variable in CO2/H2O (about 0.641) relative to inclusions in propagating rift lavas (about 0.245). This difference is considered to reflect different degrees of degassing during contrasting magmatic histories of the two regions.

Yonover, Robert N.↗
NASA NTRS1991

Heat flow vs. atmospheric greenhouse on early Mars

Researchers derived a quantitative relationship between the effectiveness of an atmospheric greenhouse and internal heat flow in producing the morphological differences between earlier and later Martian terrains. The derivation is based on relationships previously derived by other researchers. The reasoning may be stated as follows: the CO2 mean residence time in the Martian atmosphere is almost certainly much shorter than the total time span over which early climate differences are thought to have been sustained. Therefore, recycling of previously degassed CO2 quickly becomes more important than the ongoing supply of juvenile CO2. If so, then the atmospheric CO2 pressure, and thereby the surface temperature, may be approximated mathematically as a function of the total degassed CO2 in the atmosphere plus buried material and the ratio of the atmospheric and regolith mean residence times. The latter ratio can also be expressed as a function of heat flow. Hence, it follows that the surface temperature may be expressed as a function of heat flow and the total amount of available CO2. However, the depth to the water table can simultaneously be expressed as a function of heat flow and the surface temperature (the boundary condition). Therefore, for any given values of total available CO2 and regolith conductivity, there exist coupled independent equations which relate heat flow, surface temperature, and the depth to the water table. This means we can now derive simultaneous values of surface temperature and the depth of the water table for any value of the heat flow. The derived relationship is used to evaluate the relative importance of the atmospheric greenhouse effect and the internal regolith thermal gradient in producing morphological changes for any value of the heat flow, and to assess the absolute importance of each of the values of the heat flow which are thought to be reasonable on independent geophysical grounds.

Fanale, F. P.↗
NASA NTRS1993

Helium-3 from the mantle - Primordial signal or cosmic dust?

Helium-3 in hotspot magmas has been used as unambiguous evidence for the existence of a primordial, undegassed reservoir deep in the Earth's mantle. However, a large amount of helium-3 is delivered to the Earth's surface by interplanetary dust particles (IDPs). Recycling of deep-sea sediments containing these particles to the mantle, and eventual incorporation in magma, can explain the high helium-3/helium-4 ratios of hotspot magmas. Basalts with high helium-3/helium-4 ratios may represent degassing of helium introduced by ancient (probably 1.5 to 2.0 billion years old) pelagic sediments rather than degassing of primordial lower mantle material brought to the surface in plumes. Influx of IDPs can also explain the neon and siderophile compositions of mantle samples.

Anderson, Don L.↗
NASA NTRS1993

Implantation of nitrogen: Effects of hydrogen and implantation energy

To solve the question on solar nitrogen in lunar soils, i.e. variation in isotopic composition and apparently high retentivity compared with rare gases, nitrogen implantation experiments were conducted. At the Meteoritical Society Meeting in Copenhagen, the results of stepped combustion of implanted nitrogen in ilmenite and olivine were presented. The degassing behavior of nitrogen (and also Ar) was quite different from that observed in the case of lunar soils. Extraction temperatures are higher (greater than 1100 C for ilmenite and 1500 C for olivine) than that for lunar soils. Both nitrogen and Ar seem to be retained at the same efficiency. Therefore, additional experiments were conducted to make degassing behavior of nitrogen more close to that observed in the case of lunar soils.

Sugiura, Naoji↗
NASA NTRS1993

Evolution of the Martian atmosphere

Evolution of Mars' noble gases through two stages of hydrodynamic escape early in planetary history has been proposed previously by the author. In the first evolutionary stage of this earlier model, beginning at a solar age of approximately 50 m.y., fractionating escape of a H2-rich primordial atmosphere containing CO2, N2, and the noble gases in roughly the proportions found in primitive carbonaceous (CI) chondrites is driven by intense extreme-ultraviolet (EUV) leads to a long (approximately 80 m.y.) period of quiescence, followed by an abrupt degassing of remnant H2, CO2, and N2 from the mantle and of solar-composition noble gases lighter than Xe from the planet's volatile-rich accretional core. Degassed H refuels hydrodynamic loss in a waning but still potent solar EUV flux. Atmospheric Xe, Kr, and Ar remaining at the end of this second escape stage, approximately 4.2 G.y. ago, have evolved to their present-day abundances and compositions. Residual Ne continues to be modified by accretion of solar wind gases throughout the later history of the planet. This model does not address a number of processes that now appear germane to Martian atmospheric history. One, gas loss and fractionation by sputtering, has recently been shown to be relevant. Another, atmospheric erosion, appears increasingly important. In the absence then of a plausible mechanism, the model did not consider the possibility of isotopic evolution of noble gases heavier than Ne after the termination of hydrodynamic escape. Subsequent non-thermal loss of N was assumed, in an unspecified way, to account for the elevation of N from the model value of approximately 250 percent at the end of the second escape stage to approximately 620 percent today. Only qualitative attention was paid to the eroding effects of impact on abundances of all atmophilic species prior to the end of heavy bombardment approximately 3.8 G.y. ago. No attempt was made to include precipitation and recycling of carbonates in tracking the pressure and isotopic history of CO2.

Pepin, R. O.↗
NASA NTRS1994

Atmospheres of the Moon and Mercury

Mercury and the Moon have long been considered to be similar objects, but this view was based on limited information at visible wavelengths. It is now known that real differences exist in the atmospheres and in the rock types as deduced from mid-infrared observations. Lunar Ar and perhaps Ne were observed from Apollo landed experiments in spite of a large local background. An ultraviolet spectrometer (UVS) in orbit placed upper limits on a number of gases including H and O. At Mercury, the UVS on Mariner 10 measured H, He, and perhaps O and again a number of upper limits for other gases. Less than a decade ago, emissions of Na and K were observed from the ground, with abundances 2 orders of magnitude smaller on the Moon than on Mercury. It is likely that impacting meteoroids bring a significant amount of water to Mercury, whose atmosphere should therefore contain water vapor. This notion is supported by the recent discovery of radar-bright polar deposits almost certainly composed of ice. A variety of origins is likely for the different components. Impact of meteoroids could supply water, Na, and K, and could also vaporize surface material; Na, K, and Ar could be degassed from the crust. H is probably from the solar wind, and He could reasonably come from degassing or the solar wind. A substantial loss process for all components is photoionization (or dissociation); ions on one side are swept away into the solar wind and on the other are swept back to the surface. This process is complicated at Mercury by its permanent magnetic field, but there is little doubt that both loss and recycling still occur. Some of the recycling probably occurs by way of the magnetotail through night side auroral precipitation; atoms implanted in the surface will diffuse back into the atmosphere shortly after dawn, an effect that seems to be present for K. Finally the light atoms H and He have high enough velocities to escape directly, an effect that may be enhanced by the suprathermal velocity distributions that are likely to be present.

Hunten, D. M.↗