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At least 613 records · Page 34

All sources NASA NTRS DOE OSTI

NASA NTRS1978

Analysis, design, fabrication and testing of the mini-Brayton rotating unit (Mini-BRU). Volume 1: Text and tables

A 500 to 2100 watt power output Mini-Brayton Rotating Unit (Mini-BRU)was analyzed, designed, fabricated and tested. Performance and test data for the various components is included. Components tested include the 2.12 in. diameter compressor, the 2.86 in. diameter turbine, the Rice alternator and the cantilevered foil-type journal and thrust bearings. Also included are results on the fabrication of a C-103 turbine plenum/nozzle assembly and on offgassing of the organic materials in the alternator stator.

Dobler, F. X.↗

NASA NTRS1978

A method of exploration of the atmosphere of Titan

A hot-air balloon, with the air heated by natural sources, is described. Buoyancy is accomplished by either solar heating or by utilizing the IR thermal flux of the planet to heat the gas in the balloon. Altitude control is provided by a valve which is opened and closed by a barometer. The balloon is made of an organic material which has to absorb radiant energy and to emit as little as possible.

Blamont, J.↗

NASA NTRS1978

Viking - The exploration of Mars

The Viking 1 and 2 spacecraft were launched in August and September, 1975 on a ten month journey to begin an in depth study of the nature, origin and evolution of Mars. Upon arrival at Mars, the previously selected Viking 1 landing site was found to be unsuitable and a new site was selected by means of cameras mounted on the Viking orbiter, which also revealed features suggesting a history of liquid water on the Martian surface. Once the new site in the Cryse basin was selected, the Viking 1 lander separated from the orbiter and landed on July 20, 1976, followed by the Viking 2 lander in August, 1976 at a site considerably to the north of the first site. At the two sites, scanning facsimile cameras allowed the panoramic imaging of the terrain and measurements were made of local atmospheric and soil compositions, temperatures, pressures, winds and seasonal changes. Soil analyzers have not detected the presence of organic materials at these sites, and although the results of the life detection experiments are ambiguous, the likelihood of life on Mars seems extremely remote.

Young, R. S.↗

NASA NTRS1980

Thermal history, chemical composition and relationship of comets to the origin of life

The role of thermal processes in determining the chemical composition of comets is considered, and implications of possible cometary constituents for the origin and evolution of life on earth are discussed. It is shown that the inclusion of short-lived Al-26 from a nearby supernova explosion into cometary nuclei could lead to comets with surfaces cool enough to retain H2O and interiors warm enough for thermal processing to occur, with the production of complex organic molecules such as amino acids and nucleic acid bases. It is thus suggested that comets may have played a part in seeding the primitive earth with biological polymers capable of self-replication or of evolving towards that capability, and may even be responsible for the subsequent introduction of organic material capable of infecting already existing cells.

Irvine, W. M.↗

NASA NTRS1979

The photolytic degradation and oxidation of organic compounds under simulated Martian conditions

Cosmochemical considerations suggest various potential sources for the accumulation of organic matter on Mars. However the Viking Molecular Analysis did not indicate any indigenous organic compounds on the surface of Mars. Their disappearance from the top layer is most likely caused by the combined action of the high solar radiation flux and various oxidizing species in the Martian atmosphere and regolith. In this study the stability of several organic substances and a sample of the Murchison meteorite was tested under simulated Martian conditions. After adsorption on powdered quartz, samples of adenine, glycine and naphthalene were irradiated with UV light at various oxygen concentrations and exposure times. In the absence of oxygen, adenine and glycine appeared stable over the given irradiation period, whereas a definite loss was observed in the case of naphthalene, as well as in the volatilizable and pyrolizable content of the Murchison meteorite. The presence of oxygen during UV exposure caused a significant increase in the degradation rate of all samples. It is likely that similar processes have led to the destruction of organic materials on the surface of Mars.

Oro, J.↗

NASA NTRS1982

Heat-Exchange Fluids for Sulfuric Acid Vaporizers

Some fluorine-substituted organic materials meet criteria for heat-exchange fluids in contact with sulfuric acid. Most promising of these are perfluoropropylene oxide polymers with degree of polymerization (DP) between 10 and 50. It is desirable to have DP in high range because vapor pressure of material decreases as DP increases, and high-DP liquids have lower loss due to vaporization.

Lawson, D. D.↗

NASA NTRS1980

An industrial application of the JPL ACTS with energy recovery

The JPL Activated Carbon Treatment System (ACTS) uses sewage solids derived from municipal wastewater treatment systems as a source of organic material for powdered activated carbons (PAC). The PAC is used for the COD removal from wastewater and as a filter aid in the recovery of additional sewage solids.

Humphrey, M. F.↗

NASA NTRS1980

Carbonaceous chondrites. II - Carbonaceous chondrite phyllosilicates and light element geochemistry as indicators of parent body processes and surface conditions

Petrographic analyses of CM matrices characterized four phyllosilicates in Murray and Murchison meteorites and Fe- and Mg-serpentines in Nogoya. All phyllosilicates and bulk matrices show enrichment of K relative to Na when compared with bulk meteorites; the loss of Na and some Cl, and the addition of H2O, CO2, and water-soluble organics during alteration indicates a partially open system. Synthesis of soluble organic materials may have occurred in CM matrices before aqueous alteration of the precursive phases. Nogoya was 95% altered and has a bulk C content of 5.2%, higher than any meteorite; also, it has the lowest measured C-13/C-12 ratio of any carbonaceous chondrite except for Karoonda.

Bunch, T. E.↗

NASA NTRS1981

The relationship among sea surface roughness variations, oceanographic analyses, and airborne remote sensing analyses

The synthetic aperture radar (SAR) was studied to determine whether it could image large scale estuaries and oceanic features such as fronts and to explain the electromagnetic interaction between SAR and the individual surface front features. Fronts were observed to occur at the entrance to the Chesapeake Bay. The airborne measurements consisted of data collection by SAR onboard an F-4 aircraft and real aperture side looking radar (SLAR) in Mohawk aircraft. A total of 89 transects were flown. Surface roughness and color as well as temperature and salinity were evaluated. Cross-frontal surveys were made. Frontal shear and convergence flow were obtained. Surface active organic materials, it was indicated, are present at the air-sea interface. In all, 2000 analyses were conducted to characterize the spatial and temporal variabilities associated with water mass boundaries.

Oertel, G. F.↗

NASA NTRS1982

J series thruster thermal test results

Test experience with J series ion thrusters have indicated that the present thruster design may result in excessive temperatures in areas which utilize organic materials such as wire insulation, with the resultant outgassing and potential contamination of insulating materials. Further, it appears that thermal data obtained with earlier thruster designs, such as the 700 series thruster, may not be directly applicable to the J series design. Two J series thrusters were fitted with thermocouples and critical temperatures measured for a variety of configurations and operating parameters. Completely enclosing the thruster to reduce facility contamination significantly increased temperatures prompting the selection of a compromise geometry for life testing. The operating parameter having the largest effect on temperatures was discharge power, while beam power affected little else than extraction system temperatures. Several off-normal operating modes were also investigated. Data believed to be sufficient to effectively modify existing thermal models were obtained from the tests.

Bechtel, R. T.↗

NASA NTRS1982

Delineation of estuarine fronts in the German Bight using airborne laser-induced water Raman backscatter and fluorescence of water column constituents

The acquisition and application of airborne laser induced emission spectra from German Bight water during the 1979 MARSEN experiment is detailed for the synoptic location of estuarine fronts. The NASA Airborne Oceanographic Lidar (AOL) was operated in the fluorosensing mode. A nitrogen laser transmitter at 337.1 nm was used to stimulate the water column to obtain Gelbstoff or organic material fluorescence spectra together with water Raman backscatter. Maps showing the location and relative strength of estuarine fronts are presented. The distribution of the fronts indicates that mixing within the German Bight takes place across a relatively large area. Reasonable agreement between the patterns observed by the AOL and published results are obtained. The limitations and constraints of this technique are indicated and improvements to the AOL fluorosensor are discussed with respect to future ocean mapping applications.

Hoge, F. E.↗

NASA NTRS1982

Supercritical water oxidation for wastewater treatment Preliminary study of urea destruction

Supercritical water oxidation is being investigated as a method of treating spacecraft wastewater for recycle. In this process, oxidation is conducted in an aqueous phase maintained above the critical temperature (374 C) and pressure (215 bar) of water. Organic materials are oxidized with efficiencies greater than 99.99 percent in residence times of less than 1 minute. This paper presents preliminary results for urea destruction. Above 650 C, urea can be completely broken down to nitrogen gas, carbon dioxide and water by supercritical water oxidation, without the use of a specific catalyst.

Timberlake, S. H.↗

NASA NTRS1985

Low-Temperature Extraction of Oil From Shale

Technique increases recovery and energy efficiency. Advantages of method greater product yield and, because of the relatively low temperatures, minimal gas formation, smaller amounts of char byproduct, and less carbonate-rock decomposition. Up to 94 percent by weight of organic material in shale extracted.

Compton, L. E.↗

NASA NTRS1984

Fire blocking systems for aircraft seat cushions

A configuration and method for reducing the flammability of bodies of organic materials that thermally decompose to give flammable gases comprises covering the body with a flexible matrix that catalytically cracks the flammable gases to less flammable species. Optionally, the matrix is covered with a gas impermeable outer layer. In a preferred embodiment, the invention takes the form of an aircraft seat in which the body is a poly(urethane) seat cushion, the matrix is an aramid fabric or felt and the outer layer is an aluminum film.

Parker, J. A.↗

NASA NTRS1983

Contamination sensitivity of typical mirror coatings - A parametric study

Contamination budgeting for space optical systems basically starts at understanding the sensitivity of component performance, e.g. mirror reflectance, window transmittance, etc., to surface deposits. To evaluate contamination sensitivity for mirror coatings, eight types representative of those used in the vacuum ultraviolet, visible, and infrared were modeled assuming that the contaminant is uniformly deposited on the mirror surface. Parametric studies over a range of complex refractive indices combined with an examination of optical data available for several organic materials suggested division of the contaminant layer index into three categories, N = 1.5 + 0.1i, N = 1.5 + 0.5i, and N = 1.5 + 2.0i. Contaminant thickness sensitivity curves were then calculated for each of the selected mirror coatings. For comparative purposes, critical thicknesses for each type were extracted, assuming a reflectance loss of 10 percent was allowable. Critical thicknesses ranged from about 10 A to 1000 A depending on the specifics of coating design and spectral region.

Osantowski, J. F.↗

NASA NTRS1984

Mechanisms of nitrogen retention in forest ecosystems - A field experiment

Intensive forest management led to elevated losses of nitrogen from a recently harvested loblolly pine plantation in North Carolina. Measurements of nitrogen-15 retention in the field demonstrated that microbial uptake of nitrogen during the decomposition of residual organic material was the most important process retaining nitrogen. Management practices that remove this material cause increased losses of nitrogen to aquatic ecosystems and the atmosphere.

Vitousek, P. M.↗

NASA NTRS1983

Geochemical evidence bearing on the origin of aerobiosis, a speculative hypothesis

It is pointed out that the atmosphere and hydrosphere of the early Archean earth were essentially anoxic. The paleontological record shows that life existed in spite of the absence of oxygen. The present investigation is concerned with the presentation of a plausible sequence of events, linking features in the carbon isotopic record to the origin of oxygenic photosynthesis. The investigation takes into account that the record of carbon isotopic abundances in sedimentary organic matter displays marked variations about 2.8 Ga before the present. At least by 2.8 Ga before the present, if not before, something in the carbon cycle began to allow the incorporation in sediments of organic material extraordinarily depleted in C-13. Attention is given to a model for the development of C-13 depleted kerogens, conclusions regarding the late Archean carbon cycle, and the transition in the global ecosystem.

Hayes, J. M.↗

NASA NTRS1985

The production of glow precursors by oxidative erosion of spacecraft surfaces

Erosion rates of organic materials are measured during a recent flight of the shuttle (STS-8). Several forms of carbon and a variety of thermosetting and thermoplastic polymers are exposed to the ram beam of atomic oxygen. Arrhenius energies of about 1000 to 2000 cal/mole were measured from the rate dependencies on temperature. If some simple assumptions are made about the chemical nature of the desorbed species, the data can be used to estimate production rates at surfaces in orbit under different conditions of temperature, oxygen atom flux, and material surface conditions.

Gregory, J. C.↗