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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

We report the first observations of energetic neutral atoms (ENAs) from a solar flare/coronal mass ejection event. The observations were made during the December 5, 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on the STEREO A and B spacecraft. Within 1-2 hours of the flare onset, both LETs observed a sudden burst of 1.6 to 15 MeV protons arriving hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within +-10 degrees of the Sun. The derived emission profile at the Sun lasted for more than an hour and had a profile remarkably similar to the GOES soft X-ray profile. The observed arrival directions and energy spectrum argue strongly that the particle events <5 MeV were due to energetic neutral hydrogen atoms that were stripped of their electrons upon entering the LET sensor. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. We discuss possible origins for the production of ENAs in solar events, including charge-transfer reactions involving both flare and shock-accelerated protons. Assuming isotropic emission, we find that ~2 x 10E28 ENAs escaped from the Sun in the upper hemisphere. Based on the 2.2 MeV gamma-ray emission observed by RHESSI in this event, and using measured and theoretical cross sections, we estimate that ~3 x 10E31 ENAs with 1.8 - 5 MeV could be produced by protons accelerated in the flare. CME-driven shock acceleration is also a possible ENA source, but unfortunately there were no CME observations available from this event. Taking into account ENA losses, we conclude that the observed ENAs were most likely produced in the high corona at heliocentric distances 1.6 solar radii.

Mewaldt, R. A.↗
NASA NTRS1989

Element abundances at high redshift

Abundances of Si(+), S(+), Cr(+), Mn(+), Fe(_), and Zn(+) are considered for two absorption-line systems in the spectrum of the QSO PKS 0528 - 250. Zinc and sulfur are underabundant, relative to H, by a factor of 10 compared to their solar and Galactic interstellar abundances. The silicon-, chromium-, iron-, and nickel-to-hydrogen ratios are less than the solar values and comparable to the local interstellar ratios. A straightforward interpretation is that nucleosynthesis in these high-redshift systems has led to only about one-tenth as much heavy production as in the gas clouds around the sun, and that the amount of the observed underabundances attributable to grain depletion is small. The dust-to-gas ratio in these clouds is less than 8 percent of the Galactic value.

Meyer, David M.↗
NASA NTRSDate not supplied

Hydrogen Production From Sulfide Minerals as A Potential Resource on Mars

Space exploration has entered new era where we seek to establish a sustainable human presence on bodies such as the Moon and Mars. This is one of the most ambitious efforts undertaken by humankind and brings with it new challenges. Among these challenges is providing the resources required for habitation of other solar system bodies. The Earth’s gravity is immense, and thus, propellent loads make up approximately 90% of a launch vehicle mass, with deliverable payloads from Earth to other bodies of <5% of a launch vehicle mass. In addition, human missions require a return vehicle. For a target such as Mars, propellent requirements for the return vehicle are estimated at 80% of the vehicle mass, further restricting other resource payloads.

C.T. Adcock↗
NASA NTRS2001

A Cryogenic Propellant Production Depot for Low Earth Orbit

The cost of access to space beyond low Earth orbit can be lowered if vehicles can refuel in orbit. The power requirements for a propellant depot that electrolyzes water and stores cryogenic oxygen and hydrogen can be met using technology developed for space solar power. A propellant depot is described that will be deployed in a 400 km circular equatorial orbit, receive tanks of water launched into a lower orbit from Earth by gun launch or reusable launch vehicle, convert the water to liquid hydrogen and oxygen, and store up to 500 metric tonnes of cryogenic propellants. Orbital maneuvering vehicles will transfer the Earth-launched propellant tanks from the lower orbit to the depot orbit. The propellant stored in the depot can support transportation from low Earth orbit to geostationary Earth orbit, the Moon, LaGrange points, Mars, etc. The propellant tanks on the depot are modified versions of those used in the Delta IV-Heavy launch vehicle. The tanks are configured in an in-line gravity-gradient configuration to minimize drag and settle the propellant. Temperatures can be maintained by body-mounted radiators; these will also provide some shielding against orbital debris. Power is supplied by a pair of solar arrays mounted perpendicular to the orbital plane, which rotate once per orbit to track the Sun. The majority of the power will be used to run the electrolysis system. Technology needed for an orbiting propellant depot can be tested and demonstrated in the near-term on the ground, on a Shuttle-deployed free-flyer, and on the International Space Station. Further along, an orbital depot can be deployed that stores liquid hydrogen and oxygen launched from Earth, to be followed by a full conversion and storage depot.

Potter, Seth D.↗
NASA NTRS2014

Organic Analysis of Catalytic Fischer-Tropsch Type Synthesis Products: Are they Similar to Organics in Chondritic Meteorites?

Fischer-Tropsch Type (FTT) synthesis of organic compounds has been hypothesized to occur in the early solar nebula that formed our Solar System. FTT is a collection of abiotic chemical reactions that convert a mixture of carbon monoxide and hydrogen over nano-catalysts into hydrocarbons and other more complex aromatic compounds. We hypothesized that FTT can generate similar organic compounds as those seen in chondritic meteorites; fragments of asteroids that are characteristic of the early solar system. Specific goals for this project included: 1) determining the effects of different FTT catalyst, reaction temperature, and cycles on organic compounds produced, 2) imaging of organic coatings found on the catalyst, and 3) comparison of organic compounds produced experimentally by FTT synthesis and those found in the ordinary chondrite LL5 Chelyabinsk meteorite. We used Pyrolysis Gas Chromatography Mass Spectrometry (PY-GCMS) to release organic compounds present in experimental FTT and meteorite samples, and Scanning Electron Microscopy (SEM) to take images of organic films on catalyst grains.

Yazzie, Cyriah A.↗
NASA NTRS1978

Low Cost Silicon Solar Array Project. Feasibility of Low-cost, High-volume Production of Silane and Pyrolysis of Silane to Semiconductor-grade Silicon

The presence of copper promotes a more rapid approach to the steady stete operating condition and results in a more consistent reactor effluent composition. The average kinetic and equilibrium yield are unchanged. Incoloy has been identified as the preferred choice of material of construction for the hydrogenation reactor although certain metallurgical changes were noted in samples exposed to the H2/HCl atmosphere at 500 C which indicate the need for more testing.

Breneman, W. C.↗
NASA NTRS1993

Analysis of hydrogen H-alpha observations of the coma of Comet P/Halley

The Monte Carlo Particle Trajectory Model of Combi and Smyth (1988) is used here to analyze observations of the H-alpha coma of Comet Halley. The solar excitation mechanism for the H-alpha emissions line is described. The H2O production rates derived for the H-alpha brightness measurements are shown to be very consistent with the H2O production rates determined from other Comet Halley observations of the H, O, and OH comae. Revised H2O production rates determined from 6300 A brightness measurements are presented.

Smyth, William H.↗
NASA NTRS1972

Effects of interstellar particles upon the interplanetary magnetic field

The flow of interstellar neutral particles into the interplanetary medium and their subsequent ionization in the presence of the electromagnetic field of the solar wind can cause a loss of field angular momentum by the solar wind. One effect of this loss of field angular momentum is a significant unwinding of the spiral field. This effect is evaluated using simple models for neutral density and ion production. For a free-stream interstellar medium with a neutral hydrogen density of 1 per cubic centimeter and a velocity relative to the sun of 10 to 20 km per second, the spiral angle at the orbit of Jupiter will be less than its nominal value of 45 deg at the orbit of the earth.

Coleman, P. J., Jr.↗
NASA NTRS1971

Some implications of a new value for the primordial solar deuterium-hydrogen ratio.

Some astrophysical implications of a primordial solar D/H ratio of 0.000015 are investigated. Perhaps the most interesting aspects of the D/H ratio concern galactic evolution and cosmology. It is shown that the initial galactic abundance of deuterium exceeds by at least a factor of 30 the abundance expected from known galactic production mechanisms. If a Friedmann cosmology is a correct description of the universe, it must be an open one unless some as yet unknown mechanism is invo ked to produce deuterium and He-3.

Black, D. C.↗
NASA NTRS1977

Thermochemical water decomposition

At present, nearly all of the hydrogen consumed in the world is produced by reacting hydrocarbons with water. As the supply of hydrocarbons diminishes, the problem of producing hydrogen from water alone will become increasingly important. Furthermore, producing hydrogen from water is a means of energy conversion by which thermal energy from a primary source, such as solar or nuclear fusion of fission, can be changed into an easily transportable and ecologically acceptable fuel. The attraction of thermochemical processes is that they offer the potential for converting thermal energy to hydrogen more efficiently than by water electrolysis. A thermochemical hydrogen-production process is one which requires only water as material input and mainly thermal energy, or heat, as an energy input. Attention is given to a definition of process thermal efficiency, the thermodynamics of the overall process, the single-stage process, the two-stage process, multistage processes, the work of separation and a process evaluation.

Funk, J. E.↗
NASA NTRS1984

Changes of LISM Characteristics in the Heliospheric Interface

The LISM properties can be deduced from observations of interstellar neutral gases in the inner solar system. Parameters accessible by this method are the interstellar wind vector and the densities and temperatures of hydrogen and helium, implying also the deduction of the relative abundance ratios and the degree of ionization in the LISM. Direct inference from observations, for example resonance luminescence measurements of Ly-alpha and He-58.4 nm radiation, yields values appropriate only for the inner solar system, i.e. for the regions within the heliopause dominated by the solar wind plasma. Particularly the subsonic LISM plasma interface ahead of the heliopause causes profound changes in the properties of the neutral LISM gas traversing this region. Mainly p-H charge exchange processes ive rise to the destruction of primary hydrogen and the production of secondary hydrogen atoms, the net effect being a depletion of the neutral hydrogen component of the LISM by about 50%. Details on the depletion mechanisms, the hydrogen and oxygen extinctions, and the consequences for the Ly-alpha resonance luminescence intensity interpretations are presented.

Ripken, H. W.↗
NASA NTRS1975

An investigation of the solar zenith angle variation of D-region ionization

Model calculations are carried out with a view to interpreting the solar zenith angle variation of D-region ionization. A model is developed for the neutral chemistry including the transport terms relating to molecular and eddy diffusion. The diurnal behavior is described of the minor neutral constituents formed in an oxygen-hydrogen-nitrogen atmosphere, in the height interval between 30 and 120 km. Computations carried out for two cases of the eddy diffusion coefficients models indicate that the constituents which are important for the D-region positive-ion chemistry do not show a significant variation with zenith angle for values up to 75 deg over the D-region heights. In the ion chemistry model, ion-pair production rates are calculated for solar X-rays between 1 A and 100 A, EUV radiations from 100 A up to the Lyman-alpha line, precipitating electrons, and galactic cosmic rays. The solar zenith angle variation of the positive-ion composition, negative-ion composition, and the electron densities are described up to 75 deg zenith angle, in the height interval between 60 and 100 km.

Ratnasiri, P. A. J.↗
NASA NTRS1983

Development of an all-metal thick film cost effective metallization system for solar cells

Improved thick film solar cell contacts for the high volume production of low cost silicon solar arrays are needed. All metal screenable pastes made from economical base metals and suitable for application to low to high conductivity silicon were examined. Silver fluoride containing copper pastes and fluorocarbon containing copper pastes were discussed. The effect of hydrogen on the adhesion of metals to silicon was investigated. A cost analysis of various paste materials is provided.

Ross, B.↗
NASA NTRS1982

The influence of thermospheric winds on exospheric hydrogen on Venus

Monte Carlo models of the distribution of atomic hydrogen in the exosphere of Venus were computed which simulate the effects of thermospheric winds and the production of a 'hot' hydrogen component by charge exchange of H(+) and H and Q in the exosphere, as well as classic exospheric processes. A thermosphere wind system that is approximated by a retrograde rotating component with equatorial speed of 100 m/sec superimposed on a diurnal solar tide with cross-terminator day-to-night winds of 200 m/sec is shown to be compatible with the thermospheric hydrogen distribution deduced from Pioneer Venus orbiter measurements.

Hodges, R. R., Jr.↗
NASA NTRS1973

Organic compounds in meteorites

The problem of whether organic compounds originated in meteorites as a primary condensate from a solar gas or whether they were introduced as a secondary product into the meteorite during its residence in a parent body is examined by initially attempting to reconstruct the physical conditions during condensation (temperature, pressure, time) from clues in the inorganic matrix of the meteorite. The condensation behavior of carbon under these conditions is then analyzed on the basis of thermodynamic calculations, and compounds synthesized in model experiments on the condensation of carbon are compared with those actually found in meteorites. Organic compounds in meteorites seem to have formed by catalytic reactions of carbon monoxide, hydrogen, and ammonia in the solar nebula at 360 to 400 K temperature and about 3 to 7.6 microtorr pressure. The onset of these reactions was triggered by the formation of suitable catalysts (magnetite, hydrated silicates) at these temperatures.

Anders, E.↗
NASA NTRS1973

Conclusions and recommendations of the United States Solar Energy Panel

The United States Solar Energy Panel was charged with assessing the potential of solar energy as a national energy resource. Three areas evolved where solar energy could supply significant amounts of the U.S. future energy needs: (1) energy for heating and cooling of buildings, (2) the production of fuels, and (3) the generation of electrical power. It was concluded that with adequate R&D support over the next 30 years, solar energy could provide at least 35 percent of the heating and cooling of future buildings, greater than 30 percent of the methane and hydrogen needed in the U.S. for gaseous fuels, and greater than 20 percent of the electrical power needs of the U.S. All of this could be done with a minimal effect on the environment and a substantial savings of nonrenewable fuels.

Cherry, W. R.↗
NASA NTRS1974

Amino acids in a Fischer Tropsch type synthesis

One postulation is described for the presence of organic compounds in meteorites which states that they were formed during the condensation of the solar nebula. A viable laboratory simulation of these conditions can be modeled after the industrial Fischer Tropsch reaction, which is known to produce organic compounds called hydrocarbons. In this simulation, a mixture of carbon monoxide, hydrogen and ammonia is heated in the presence of iron meteorite. The reaction products for amino acids, a class of organic compounds important to life, were examined. A large number of these compounds is found in meteorites and other chemical evolution experiments, but only small quantities of a few amino acids were found in the present simulation work. These results are at odds with the existing literature in which many amino acids were reported.

Brown, D. L.↗
NASA NTRS2006

Evaluation of a Stirling Solar Dynamic System for Lunar Oxygen Production

An evaluation of a solar concentrator-based system for producing oxygen from the lunar regolith was performed. The system utilizes a solar concentrator mirror to provide thermal energy for the oxygen production process as well as thermal energy to power a Stirling heat engine for the production of electricity. The electricity produced is utilized to operate the equipment needed in the oxygen production process. The oxygen production method utilized in the analysis was the hydrogen reduction of ilmenite. Utilizing this method of oxygen production a baseline system design was produced. This baseline system had an oxygen production rate of 0.6 kg/hr with a concentrator mirror size of 5 m. Variations were performed on the baseline design to show how changes in the system size and process rate effected the oxygen production rate.

Colozza, Anthony J.↗