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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Ice Growth Model and Lunar Tanker for Polar Water Extraction

In-Situ Resource Utilization (ISRU) is a major component of sustainable and cost-effective missions to the Moon and beyond. Ever since it has been identified in the Permanently Shadowed Regions (PSRs) of the Moon, water has become a resource of interest for it’s wide range of uses such as life support and hydrogen and oxygen rocket propellant. It is ice-bound in the regolith, so separation typically involves heating to sublimation temperatures and capturing at very low pressure. One option is to then store it in ice form and transport it out of the PSR and into a sunlit ridge. From here, processes such as electrolysis can be performed. An understanding of frost growth dynamics under rarefied conditions is necessary for successful water production, though. An analytical model was developed using a Diffusion-Limited Aggregation (DLA) approach to evaluate bulk thermal conductivity changes of frost under varying conditions. This model will be evaluated using a one-dimensional frost growth experiment on a horizontal, flat plate under vacuum and cryogenic conditions. The tests will measure frost growth rate and bulk density, and the thermal conductivity of the ice layer as a function of thickness for different plate temperatures. The test data will then be used to validate and improve the analytical model.

Lunar water↗
NASA NTRS1995

Measurement of precipitation induced FUV emission and Geocoronal Lyman Alpha from the IMI mission

This final report describes the activities of the Lockheed Martin Palo Alto Research Laboratory in studying the measurement of ion and electron precipitation induced Far Ultra-Violet (FUV) emissions and Geocoronal Lyman Alpha for the NASA Inner Magnetospheric Imager (IMI) mission. this study examined promising techniques that may allow combining several FUV instruments that would separately measure proton aurora, electron aurora, and geocoronal Lyman alpha into a single instrument operated on a spinning spacecraft. The study consisted of two parts. First, the geocoronal Lyman alpha, proton aurora, and electron aurora emissions were modeled to determine instrument requirements. Second, several promising techniques were investigated to determine if they were suitable for use in an IMI-type mission. Among the techniques investigated were the Hydrogen gas cell for eliminating cold geocoronal Lyman alpha emissions, and a coded aperture spectrometer with sufficient resolution to separate Doppler shifted Lyman alpha components.

Mende, Stephen B.↗
NASA NTRS1987

Food production and gas exchange system using blue-green alga (spirulina) for CELSS

In order to reduce the cultivation area required for the growth of higher plants in space adoption of algae, which have a higher photosynthetic ability, seems very suitable for obtaining oxygen and food as a useful source of high quality protein. The preliminary cultivation experiment for determining optimum cultivation conditions and for obtaining the critical design parameters of the cultivator itself was conducted. Spirulina was cultivated in the 6 liter medium containing a sodium hydrogen carbonate solution and a cultivation temperature controlled using a thermostat. Generated oxygen gas was separated using a polypropyrene porous hollow fiber membrane module. Through this experiment, oxygen gas (at a concentration of more than 46 percent) at a rate of 100 to approx. 150 ml per minute could be obtained.

Oguchi, Mitsuo↗
NASA NTRS2005

Molecular Contamination on Anodized Aluminum Components of the Genesis Science Canister

Inspection of the interior of the Genesis science canister after recovery in Utah, and subsequently at JSC, revealed a darkening on the aluminum canister shield and other canister components. There has been no such observation of film contamination on the collector surfaces, and preliminary spectroscopic ellipsometry measurements support the theory that the films observed on the anodized aluminum components do not appear on the collectors to any significant extent. The Genesis Science Team has made an effort to characterize the thickness and composition of the brown stain and to determine if it is associated with molecular outgassing.Detailed examination of the surfaces within the Genesis science canister reveals that the brown contamination is observed to varying degrees, but only on surfaces exposed in space to the Sun and solar wind hydrogen. In addition, the materials affected are primarily composed of anodized aluminum. A sharp line separating the sun and shaded portion of the thermal closeout panel is shown. This piece was removed from a location near the gold foil collector within the canister. Future plans include a reassembly of the canister components to look for large-scale patterns of contamination within the canister to aid in revealing the root cause.

Burnett, D. S.↗
NASA NTRS2011

Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these "oxygenated" compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing

Mansell, J. Matthew↗
NASA NTRS2012

Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these oxygenated compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing.

Mansell, J. Matthew↗
NASA NTRS1999

Methane Pyrolysis and Disposing Off Resulting Carbon

Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is a waste of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduce the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (i) recover hydrogen from the excess methane produced by the S/E process, (ii) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (iii) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. The goals of a research program on recovery of hydrogen from methane are (in descending priority order): 1) Study the kinetics of pyrolysis to arrive at a pyrolysis reactor design that produces high yields in a confined volume at the lowest possible operating temperature; 2) Study the kinetics of carbon burnoff to determine whether high yields can be obtained in a confined volume at acceptable operating temperatures; and 3) Investigate catalytic techniques for depositing carbon as a fine soot which can be physically separated from the reactor. In the JPL program, we have made significant measurements in regard to goal 1, cursory measurements in regard to goal 2, and would plan to pursue goal 3 if additional resources are secured.

Sharma, P. K.↗
NASA NTRS1977

Nickel-hydrogen

Because of the disintegration of LaNi5 as the lattice expands on absorbing hydrogen, a nickel hydrogen cell similar to a nickel cadmium cell was designed. The positive electrode is wrapped in a microporous separator and the leads are insulated. A negative conducting grid is inserted and welded to the top of the can into an open ended container which is then turned upside down and filled so that LiNa5 powder occupies all the space not used by the rest of the components. The bottom of the can is then welded on. A fill tube is located either on the bottom or on the top of the can. When welded shut, the cell is put into a pressure bomb and the lanthanum nickel is activated at about 1,000 pounds of hydrogen. Electrolytes are added to the cell as well as whatever amount of hydrogen precharge desired, and the cell is sealed. Advantages and disadvantages of the cell are discussed.

Mchenry, E. J.↗
NASA NTRS1991

The vibrational spectrum of H2O3: An ab initio investigation

Theoretically determined frequencies and absorption intensities are reported for the vibrational spectrum of the covalent HOOOH and hydrogen bonded HO---HOO intermediates that may form in the reaction of the hydroxyl and hydroperoxyl radicals. Basis sets of DZP quality, augmented by diffuse and second sets of polarization functions have been used with CASSCF wave functions. The calculated harmonic vibrational frequencies of HOOOH have been corrected with empirical factors and presented in the form of a 'stick' spectrum. The oxygen backbone vibrations, predicted to occur at 519, 760, and 870 cm(exp -1), are well separated from most interferences, and may be the most useful for the species' identification. In the case of the hydrogen bonded isomer, emphasis has been placed upon prediction of the shifts in the intramolecular vibrational frequencies that take place upon formation of the complex. In particular, the HO stretch and HOO bend of HO2 are predicted to have shifts of -59 and 53 cm(exp -1), respectively, which should facilitate their identification. It is also noted that the antisymmetric stretching frequency of the oxygen backbone in HOOOH exhibits a strong sensitivity to the degree of electron correlation, such as has been previously observed for the same mode in ozone.

Jackels, Charles F.↗
NASA NTRS1992

The separation between gas and dust filaments at the edge of the expanding shell in Eridanus

Observations obtained from IRAS for a 120 sq deg region at the boundary of a large expanding shell in Eridanus are presented. It is found that the separation between the structures in the H I and IR emission is not due to a transition of the gas into molecular hydrogen at the location of the IR filaments. The molecular hydrogen column density of these filaments is at least two orders of magnitude below what is typically seen in high-latitude molecular clouds. As the H I and dust in this region are associated with a large expanding shell (or superbubble), the action of shocks and radiation fields may be responsible for the separations of gas and dust. Unless the gas and dust structures are resolved and lie in a favorable viewing geometry, the effect tends to be hidden. The results indicate that it is not always evident, from observations with spatial resolutions coarser than a few arcminutes, how interstellar gas and dust are related.

Verschuur, G. L.↗
NASA NTRS1992

Three-dimensional calculations of supersonic reacting flows using an LU scheme

An implicit finite volume lower-upper time-marching method which efficiently solves the complete Navier-Stokes and specied equations in a fully coupled fashion is the basis of the present 3D numerical program for simulating the supersonic reacting flows of H2 in air. The chemistry model incorporated has nine species and 18 reaction steps. Calculations are presented for flowfields of underexpanded hydrogen jets that are transversely injected into the supersonic airstream within scramjet combustors; the shock structure, separated flow regions around the injector, and combustion-product distributions are clearly represented.

Yu, Sheng-Tao↗
NASA NTRS1992

Some aspects of unsteady separation

Unsteady separation can be forced in a variety of ways and in this presentation two fundamental means will be considered: (1) the introduction of convected vorticular disturbances into the flow; and (2) the influence of a specific type of three-dimensional geometry. In both situations a response of the viscous flow near the wall is provoked wherein the fluid near the surface abruptly focuses into a narrow region that erupts from the surface into the mainstream. In two-dimensional flows, the eruption takes the form of a narrow, explosively-growing spike, while in three-dimensional situations, examples are presented which indicate that the eruption is along a narrow zone in the shape of a crescent-shaped plume. The nature of the three-dimensional flow near a circular cylinder, which is mounted normal to a flat plate, is also examined in this study. Here the three-dimensional geometry induces complex three-dimensional separations periodically. The dynamics of the generation process is studied experimentally in a water channel using hydrogen bubble wires and a laser sheet, and the main features of the laminar regime through to transition are documented.

Smith, C. R.↗
NASA NTRS1999

Methane Pyrolysis and Disposing Off Resulting Carbon

Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is wasteful of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduced the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (1) recover hydrogen from the excess methane produced by the S/E process, (2) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (3) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. Hydrogen may be obtained from methane by pyrolysis in the temperature range 10000-12000C. The main reaction products are hydrogen and carbon, though very small amounts of higher hydrocarbons, including aromatic hydrocarbons are formed. The conversion efficiency is about 95% at 12000C. One needs to distinguish between thermodynamic equilibrium conversion and conversion limited by kinetics in a finite reactor.

Sharma, P. K.↗
NASA NTRS2004

Paschen Considerations for High Altitude Airships

Recently, there have been several proposals submitted to funding agencies for long-lived high altitude (about 70,000 feet) airships for communications, surveillance, etc. In order for these airships to remain at altitude, high power, high efficiency, lightweight solar arrays must be used, and high efficiency power management and distribution systems must be employed. The needs for high power and high efficiency imply high voltage systems. However, the air pressure at these extreme altitudes is such that electrical power systems will be near the Paschen discharge minimum over a wide range of electrode separations. In this paper, preliminary calculations are made for acceptable high voltage design practices under ambient, hydrogen and helium gas atmospheres.

Ferguson, D. C.↗
NASA NTRS1986

Model ion abundances for Comet Halley

A computer model for comet comae was applied to predict ion abundances for comet Halley, assuming that the volatile component of the nucleus is 85% water and that the remaining volatile molecules are composed of carbon, nitrogen, oxygen, and sulfur. Model parameters such as heliocentric distance, size, and albedo are chosen to be consistent with the 13 to 14 March 1986 encounter of Giotto with the comet. Photoprocesses, gas-phase chemical kinetics, coma energy balance including a separate electron temperature, multifluid hydrodynamics with a transition to free molecular flow, fast streaming atomic and molecular hydrogen, and counter and cross streaming of species in the coma-solar wind interaction are taken into consideration. A comparison of the model results with data from the ion mass spectrometer at 6000 and 1500 km from the nucleus shows good agreement. Implications of the coma physics and chemistry are discussed.

Huebner, W. F.↗
NASA NTRS1993

Damped Lyman-alpha absorption in Q0957+561A, B

A series of archival IUE low-dispersion spectral observations of the double quasar Q0957+561A, B are analyzed. The components of this gravitationally lensed quasar are separated by about 6 arcsec. Damped Ly-alpha absorption at redshift z(abs) = 1.3911 with neutral hydrogen column density N(H I) about 7 x 10 exp 19/sq cm is present in the spectra of both the A and B components. Using an accepted model by Young et al. for the gravitational lens, the damped Ly-alpha absorber is inferred to have a minimum size of about 0.5/h50 kpc. The standard interpretation is that a damped Ly-alpha absorber represents a galactic or protogalactic H I disk. In the context of this standard model, the absorption-line properties and evidence for Faraday rotation are discussed.

Turnshek, David A.↗