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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 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

A global thermospheric model based on mass spectrometer and incoherent scatter data MSIS. II - Composition

Measurements of O, He, and Ar from neutral gas mass spectrometers on four satellites (Ogo 6, San Marco 3, Aeros A, and AEC-C) and inferred oxygen and hydrogen densities from an ion mass spectrometer on AE-C have been combined with a neutral temperature and nitrogen density model to produce a global model of thermospheric composition in terms of inferred variations at 120 km. The data set covers the time period from mid-1969 to mid-1975. The MSIS (mass spectrometer and incoherent scatter data) model is compared with the Ogo 6 model (Hedin et al., 1974). Ar variations at 120 km tend to be in phase with temperature variations and inverse to the He, O, and H variations.

Hedin, A. E.↗
NASA NTRS1978

Lightweight electrodes

The fabrication of a lightweight composite nickel hydroxide electrode based on nickel-coated graphite is described and its effect on the load to failure and electrical resistivity of nickel cadmium and nickel zinc systems was evaluated. The use pure lead in lead acid batteries for submarines is also discussed.

Sutula, R.↗
NASA NTRS1979

The origin of KREEP

KREEP is a lunar material having very high concentrations of incompatible elements; its name is an acronym for the incompatibles K, rare-earth elements (REE), and P. Although a few pristine (endogenously igneous) KREEPy samples were returned from the Apollo 15 and 17 sites, most KREEPy samples are polymict breccias. Most models of KREEP petrogenesis have been based on partial melting of a variety of sources. Such models fail to explain the veritable absence of variations in incompatible element patterns over the sampled portion of the moon. We have defined a KREEP component based on the average composition of Apollo 14 breccias having extremely high concentrations of incompatible elements. Normalization of accurate incompatible data for KREEPy samples from the Apollo 12, 14, 15, 16, and 17 sites to this component virtually always shows no resolvable fractionation (e.g., <10% variation in the La/Lu ratio), whereas partial melting models typically produce larger fractionations (±20–25% in La/Lu) from a factor of 2 difference in degree of partial melting. Required is a single major source that could provide KREEP to widely separated locations on the nearside of the moon. The anorthositic crust of the moon is commonly attributed to the flotation of plagioclase on a deep, moon-wide magma ocean. Fractional crystallization of this magma ocean would have produced large enrichments of incompatibles in a residual liquid. No other plausible major source of incompatibles has been proposed. We borrow the German prefix ur—meaning primeval and designate this residual liquid ‘urKREEP.’ We propose that all KREEPy rocks originated by dilution of urKREEP with crustal or mantle materials during assimilation, or zone-refining (pristine samples), or impact-induced brecciation (breccias and melt rocks). The formation of urKREEP cannot be dated precisely. Correction of breccia Rb-Sr model ages for Rb loss or gain during the early intense bombardments yields ages that cluster in the range 4.4–4.5 Gy. This implies that crystallization of the magma ocean was essentially complete at this time and is in general agreement with U-Pb evidence indicating crustal formation at 4.4 Gy. Assuming that the moon had the composition of an H-group chondrite depleted in Fe-Ni and FeS and that half the incompatibles fractionated into materials other than urKREEP, the thickness of a moon-wide urKREEP layer was <2 km. Thorium concentrations determined by gamma ray spectroscopy indicate that about 4% of the incompatibles in an H chondritic moon are now in the outermost kilometer.

Paul H. Warren↗
NASA NTRS1979

Corrosion resistance of sodium sulfate coated cobalt-chromium-aluminum alloys at 900 C, 1000 C, and 1100 C

The corrosion of sodium sulfate coated cobalt alloys was measured and the results compared to the cyclic oxidation of alloys with the same composition, and to the hot corrosion of compositionally equivalent nickel-base alloys. Cobalt alloys with sufficient aluminum content to form aluminum containing scales corrode less than their nickel-base counterparts. The cobalt alloys with lower aluminum levels form CoO scales and corrode more than their nickel-base counterparts which form NiO scales.

Santoro, G. J.↗
NASA NTRS1979

Analysis of regression methods for solar activity forecasting

The paper deals with the potential use of the most recent solar data to project trends in the next few years. Assuming that a mode of solar influence on weather can be identified, advantageous use of that knowledge presumably depends on estimating future solar activity. A frequently used technique for solar cycle predictions is a linear regression procedure along the lines formulated by McNish and Lincoln (1949). The paper presents a sensitivity analysis of the behavior of such regression methods relative to the following aspects: cycle minimum, time into cycle, composition of historical data base, and unnormalized vs. normalized solar cycle data. Comparative solar cycle forecasts for several past cycles are presented as to these aspects of the input data. Implications for the current cycle, No. 21, are also given.

Lundquist, C. A.↗
NASA NTRS1980

Improved characterization of the Si-SiO2 interface

Refined quasi-static and conductance methods, based on effectively thin composite insulating layers, low-carrier-concentration bulk semiconductors, and low-level illumination, have been applied to an improved characterization of the (100) Si-SiO2 interface. Accurate measurement of both the total density of interface states and its major components as a function of energy in the forbidden gap have been made over four decades (10-billion to 100-trillion states/eV sq cm) on a single sample. The normal U-shaped density of states is resolved into separate valence- and conduction-band-derived contributions as well as impurity-derived contributions corresponding to concentrations on the order of 20 ppm at the interface.

Su, P.↗
NASA NTRS1980

A note on the Allan Hills A77278 unequilibrated ordinary chondrite

Petrographic measures of disequilibrium in the ALHA 77278 chondrite indicate that this meteorite is more equilibrated than its exceptionally high volatile element contents suggest. Based on its metal compositions, this meteorite should be classified as an LL3 rather than an L3 chondrite.

Mcsween, H. Y., Jr.↗
NASA NTRS1985

Prediction of Combustion Gas Deposit Compositions

Demonstrated procedure used to predict accurately chemical compositions of complicated deposit mixtures. NASA Lewis Research Center's Computer Program for Calculation of Complex Chemical Equilibrium Compositions (CEC) used in conjunction with Computer Program for Calculation of Ideal Gas Thermodynamic Data (PAC) and resulting Thermodynamic Data Base (THDATA) to predict deposit compositions from metal or mineral-seeded combustion processes.

Kohl, F. J.↗
NASA NTRS1984

Drift wave instabilities in a high beta multispecies plasma

The dispersion relation for drift-Alfven waves in two-component (cold and hot), high beta inhomogeneous multispecies plasma containing protons, oxygen, and sulfur ions is solved numerically. The magnetic field is assumed to have a gradient in simple slab geometry configuration. The plasma ion composition consists of H, O, S, SO2, and Na ions. The effect of heavy ions and multiple charge states on the growth rates has been numerically estimated for assumed ion compositions. The numerical calculations of growth rates also have been performed by using ion composition and plasma parameters based on Voyager spacecraft in the magnetospheres of Jupiter and Saturn.

Patel, V. L.↗
NASA NTRS1985

Metals Electroprocessing in Molten Salts

The present study seeks to explain the poor quality of solid electrodeposits in molten salts through a consideration of the effects of fluid flow of the electrolyte. Transparent cells allow observation of electrolyte circulation by a laser schlieren optical technique during the electrodeposition of solid zinc from the molten salt electrolyte, ZnCl2 - LiCl-KCl. Experimental variables are current, density, electrolyte composition, and cell geometry. Based on the results of earlier electrodeposition studies as well as reports in the literature, these parameters are identified as having the primary influence on cell performance and deposit quality. Experiments are conducted to measure the fluid flow patterns and the electrochemical cell characteristics, and to correlate this information with the morphology of the solid electrodeposit produced. Specifically, cell voltage, cell current, characteristic time for dendrite evolution, and dendrite growth directions are noted. Their relationship to electrolyte flow patterns and the morphology of the resulting electrodeposit are derived. Results to date indicate that laser schlieren imaging is capable of revealing fluid flow patterns in a molten salt electrolyte.

Sadoway, D. R.↗
NASA NTRS1986

Physical properties of asteroids

The physical properties of asteroids were studied by telescopic observations and laboratory and theoretical work. Spectrophotometry from 0.3 to 1.1 microns and 1.2, 1.6 and 2.2 micron photometry allow spectral-compositional classification of asteroids. Based on laboratory data and telescopic observations, it was found that infrared measurements at 1.2, 1.6 and 2.2 microns provide a relatively rapid and accurate method for the classification of minor planets and are important in comparing asteroids with meteorites. This technique was proven and employed in an expanded survey of Apollo-Amor-Aten and other unusual asteroids recently scanned by IRAS.

Veeder, G. J.↗
NASA NTRS1986

The large deployable reflector: A NASA submillimeter-infrared orbiting observatory

The Large Deployable Reflector (LDR) concept is outlined. The LDR telescope is based on a 20-m diameter reflector. The primary mirror is a filled aperture made up of 84 hexagonal panels, each 2 m edge-to-edge. The panels are based on lightweight structural composite materials. The optical configuration is a four mirror two stage system. The primary mirror is passive. The active optical elements for figure control are at the quaternary mirror. The primary mirror panels are supported by a deployable PAC truss backup structure at the vertices of each hexagon. The four focal plane instruments covering the range of 30 to 1000 microns are located near the vertex of the primary mirror. Some instruments will be cooled with stored cryogens to liquid helium temperatures, others to liquid nitrogen temperatures. The spacecraft functions will be located in a resource module behind the primary mirror. The LDR will be transferred to orbit by the space transportation system and assembled and tested at the space station. It will then be boosted to an orbit of greater than or = 700 km as a free flyer.

Swanson, Paul N.↗
NASA NTRS1987

Origin of fractures, Martian polygonal terrain

It has been proposed that the origin of the polygonally fractured terrain on Mars is due to stress caused by differential settling of material deposited over an irregular base topography. The eventual goal of this study is to evaluate this proposal by construction of mathematical models for this process. These models will attempt to determine what combinations of base topography, covering material composition, and depositional rate would cause the fractures observed. Because fracture formation would largely be a function of generated stress, the first step in modeling is calculation of stresses created during settlement.

Hills, L. Scott↗
NASA NTRS1987

Ion mass spectrometer experiment for ISIS-2 spacecraft

The International Satellite for Ionospheric Studies (ISIS) program of NASA was the longest duration program in NASA history. A number of satellites were flown under this program, the last being called ISIS-2, which was launched on April 1, 1971 and operated successfully for over 13 years. An experiment called the Ion Mass Spectrometer (IMS) was flown on the ISIS-2 spacecraft. It operated for 10 years providing a large data base of positive ion composition and ion flow velocities along the orbit of the satellite, the latter being circular at 1400 km with a 90 degree inclination. The data were processed and reside in the National Space Sciences Data Center.

Hoffman, John H.↗
NASA NTRS1987

Studies of storm-time ring current from the AMPTE/CCE MEPA measurements

The evolution of the ring current for the September 4-7, 1984 storm is studied with data from the Medium Energy Particle Analyzer on the AMPTE/CCE spacecraft. From an examination of particle pressures and current densities, it is found that the leading and trailing edges of particle injections are associated with depressions and enhancements of westward current densities, respectively. Based on the ion composition measurements which cover the bulk of the ring current population, the contribution of the O(+) ions to the westward ring current density is estimated to be no more than about 25 percent for this magnetic storm.

Lui, A. T. Y.↗
NASA NTRS1988

A multicomponent model of the infrared emission from Comet Halley

The 3-200-micron emission of Comet Halley is characterized theoretically by means of numerical simulations. Models with different populations of refractory dust grains are developed, applying compositional and spectral constraints based on ground-based and spacecraft observations. The results are presented in extensive graphs and discussed in detail. Best agreement between predicted and observed Halley emission is obtained for models with 8-40 times more crystalline silicate grains (by mass) than amorphous carbon grains. For the silicate grains, the predominance of large grains and thin carbonaceous coatings are found to account for the lack of a 10-micron silicate feature and the dark appearance of the comet, respectively.

Swamy, Krishna K. S.↗
NASA NTRS1988

Proximal ecological effects of the 1980 eruptions of Mount St. Helens

The diversity of ecosystems and volcanic processes involved in the 1980 eruptions of Mount St. Helens, southwest Washington, provide an excellent setting for examining effects of volcanic events on ecosystems. These eruptions included a lateral blast, debris avalanche, mudflows, pyroclastic flows, and airfall tephra. Affected ecosystems within 30 km of the vent were lakes, streams, upland and riparian forest, and meadows. Ecological disturbances imposed by the Mount St. Helens events were predominantly physical, rather than climatic or chemical which are the dominant classes of disturbances considered in analysis of global catastrophes. Analysis of ecosystem response to disturbance should be based on consideration of composition and structure of the predisturbance system in terms that represent potential survivability of organisms, mechanisms in the primary disturbance, initial survivors, secondary disturbances arising from the primary disturbance and the biological responses to secondary disturbances, invasion of the site by new propagules, interactions among secondary disturbance processes and surviving and invading organisms. Predicting ecosystem response to disturbance is enchanced by considering the mechanisms of disturbance rather than type of disturbance. In the 1980 Mount St. Helens events, the disturbance types, involved primarily the mechanisms of sedimentation, heating, and shear stress. Each disturbance type involved one or more mechanisms. Ecosystem response varied greatly across the landscape. Analysis of ecosystem response to disturbance, regardless of type, should include detailed consideration of the properties of individual species, primary and secondary disturbance mechanisms, and their distributions across landscapes.

Swanson, F. J.↗