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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

LANDSAT data: A new perspective for geology. A review of the utilization of LANDSAT imagery for geological interpretation

Areas in which LANDSAT satellite imagery were found most useful include regional interpretations of geological structure, updating verifying of geologic maps, mineral and petroleum exploration, and the monitoring of natural hazards such as large-scale erosion and seismicity. Investigations in these areas of application demonstrated the wide variety of uses presently undertaken or envisioned for the future.

Baker, R. N.↗
NASA NTRS1977

Application of photometric analyses for interpretation of Mars-Mariner VI and VII imagery

The application of radiometric analysis in the interpretation of Mariner 6 and 7 imagery is investigated and illustrated. The following types of problems were felt could be addressed using this imagery: (1) evaluation of local reflectivity changes; (2) augmentation of geological mapping; (3) discrimination of atmospheric phenomena; and (4) investigation of polar cap structure.

Kinzly, R. E.↗
NASA NTRS1977

Geochemical and mineralogical interpretation of the Viking inorganic chemical results

The current status of geochemical, mineralogical, petrological interpretation of refined Viking Lander data is reviewed, and inferences that can be drawn from data on the composition of Martian surface materials are presented. The materials are dominantly fine silicate particles admixed with, or including, iron oxide particles. Both major element and trace element abundances in all samples are indicative of mafic source rocks (rather than more highly differentiated salic materials). The surface fines are nearly identical in composition at the two widely separated Lander sites, except for some lithologic diversity at the 100-m scale. This implies that some agency (presumably aeolian processes) has thoroughly homogenized them on a planetary scale. The most plausible model for the mineralogical constitution of the fine-grained surface materials at the two Lander sites is a fine-grained mixture dominated by iron-rich smectites, or their degradation products, with ferric oxides, probably including maghemite and carbonates (such as calcite), but not such less stable phases as magnesite or siderite.

Toulmin, P., III↗
NASA NTRS1977

The analysis and interpretation of solar X-ray photographs

The paper examines methods of analyzing and interpreting solar X-ray photographs obtained by soft X-ray telescopes such as those used during the Skylab mission, to obtain information on the physical conditions that give rise to coronal X-ray emitting features revealed by inspection or microdensitometry of the X-ray photographs. First, the differential emission measure function is defined. By choosing models for this function and calculating the integral for the irradiance at the film for each filter, one calculates the effective temperature and emission measure. This method gives correct results only when applied to isothermal regions. For heterothermal regions, a modeling approach which predicts the run of temperature and density, and thus the form of the differential measure function, is used.

Underwood, J. H.↗
NASA NTRS1977

Landsat image interpretation aids

In the Large Area Crop Inventory Experiment, image interpretation aids were produced to assist in selecting and/or identifying representative samples of signatures in a given Landsat scene. The three methods employed are based on clustering techniques, information extraction, and aggregation of like spectral information on a two-dimensional spectral plot.

Abotteen, R. A.↗
NASA NTRS1977

Interpretation of cosmological information on radio sources

The question of whether any cosmological information can be obtained from radio astronomy is considered. Specific attention is given to the discovery and cosmological interpretation of the microwave background radiation, attempts to derive a Hubble relation for the optical objects identified with radio sources, searches for relations between the angular diameters of radio sources and the redshifts of their optically identified counterparts as well as between angular diameter and radio flux, construction of log N - log S curves, and luminosity volume tests. A brief outline is given of the situation that might prevail if a significant population of radio sources is not at great distances and is associated with QSOs that have been ejected from relatively nearby galaxies. It is concluded that: (1) some types of cosmological investigations have been premature; (2) much of the discussion in this area still depends on the distances of QSOs; and (3) there is no conclusive proof that the population of radio sources is changing with epoch.

Burbidge, G.↗
NASA NTRS1978

Interpretation of Beta Lyrae. IV - Hydrogen emission profiles and the pattern of gaseous flow in the system

The paper presents an interpretation of hydrogen emission profiles found in Beta Lyrae by attributing the asymmetry of the two emission peaks of both H-alpha and H-gamma at different phases to the absorption of an expanding-rotating gaseous stream. It is proposed that different relative shifts of the absorption line with respect to the emission line exist at different phases resulting in an apparent change in the profile with phase. Based on this idea, the expected profiles at four different phases have been computed for the H-alpha and H-gamma lines. They show a general trend close to what has been observed. Based on this same idea an apparent discrepancy between the observed results of the H-gamma profile obtained at two different epochs about 15 years apart becomes understandable. Finally a physical picture that can produce this periodic shift of the emission line relative to the absorption line is proposed and discussed.

Huang, S.-S.↗
NASA NTRS1977

Interpreting statistics of small lunar craters

Some of the wide variations in the crater-size distributions in lunar photography and in the resulting statistics were interpreted as different degradation rates on different surfaces, different scaling laws in different targets, and a possible population of endogenic craters. These possibilities are reexamined for statistics of 26 different regions. In contrast to most other studies, crater diameters as small as 5 m were measured from enlarged Lunar Orbiter framelets. According to the results of the reported analysis, the different crater distribution types appear to be most consistent with the hypotheses of differential degradation and a superposed crater population. Differential degradation can account for the low level of equilibrium in incompetent materials such as ejecta deposits, mantle deposits, and deep regoliths where scaling law changes and catastrophic processes introduce contradictions with other observations.

Schultz, P. H.↗
NASA NTRS1978

Interpretation of scanning electron microscope measurements of minority carrier diffusion lengths in semiconductors

In scanning electron microscope (SEM) injection measurements of minority carrier diffusion lengths some uncertainties of interpretation exist when the response current is nonlinear with distance. This is significant in epitaxial layers where the layer thickness is not large in relation to the diffusion length, and where there are large surface recombination velocities on the incident and contact surfaces. An image method of analysis is presented for such specimens. A method of using the results to correct the observed response in a simple convenient way is presented. The technique is illustrated with reference to measurements in epitaxial layers of GaAs. Average beam penetration depth may also be estimated from the curve shape.

Flat, A.↗
NASA NTRS1978

Model for interpreting Doppler broadened optical line emission measurements on axially symmetric plasma

A plasma model, previously developed to interpret neutral-particle analyzer measurements on E x B heating devices, is adapted to analyze Doppler broadened charge-exchange-neutral lines measured by an optical monochromator. Comparison of theoretical with experimental results indicates that azimuthal drift as well as cyclotron motion are quite influential in determining line shapes and widths, and thus important in temperature determination, even when the monochromator line of sight is intersecting the plasma axis of symmetry. At this central sighting position, however, results are quite insensitive to radial ion density distribution when time lag between the charge-exchange-excitation events and emission is neglected. Line shapes and widths obtained by sighting across chords of plasma at various distances from the plasma axis of symmetry indicate a strong dependence on time lag.

Englert, G. W.↗
NASA NTRS1975

The petrogenesis of 77115 and its xenocrysts - Description and preliminary interpretation

77115, a fragment-laden feldspathic pigeonite basalt, is one of four hand specimen-size samples collected from a boulder about 2.5 m across at Station 7, Taurus-Littrow. 77115 crystallized rapidly from a melt at or near the lunar surface and contains a population of xenoliths and xenocrysts which must have come from two or more separate sources. Broad reaction rims present in many of the xenocrysts suggest that cooling of the melt may have been very slow initially and rapid in the latter stage to produce the very fine-grained matrix. If the requirement for two cooling rates can be established, this will favor an endogenous igneous origin rather than an impact origin for the melt. Another interpretation is that the matrix crystallized first, followed by subsolidus reaction between xenocrysts and matrix to form the rims. The Apollo 17 feldspathic pigeonite basalts are postulated to be the dominant rock types of the early lunar crust.

Chao, E. C. T.↗
NASA NTRS1975

Mare basalts - Melting experiments and petrogenetic interpretations

Equilibrium crystallization sequences are determined in melting experiments in vacuum at Fe saturation on synthetic mare basalt compositions 70215 and 15318 Red Glass (both high-Ti) as well as 15555-15016 (low-Ti). The experiments confirm that much of the chemical variation within both the high- and low-Ti suites is controlled by near-surface fractionation processes, although the two suites cannot be related by such mechanisms. The components and crystallization products of the liquidus at various temperatures and pressures are reported. Mare basalt petrogenesis is interpreted in terms of high-pressure equilibria at Fe saturation; it is suggested that low-Ti basalts represent partial melts of a differentiated olivine-pyroxenite lunar mantle at 240 km or deeper, while cumulus clinopyroxene in the source is responsible for their REE characteristics. The formation of high-Ti basalts is considered.

Kesson, S. E.↗
NASA NTRS1978

Limb brightening on Uranus - An interpretation of the lambda 7300 A methane band

Measurements of limb brightening on the Uranus disk within the lambda 7300 A CH4 band are interpreted using an elementary inhomogeneous radiative transfer model to describe the atmosphere. A two layer model which consists of a finite, optically thin, region of conservatively scattering particles overlying a semi-infinite clear H2-CH4 atmosphere satisfactorily explains the observations. The maximum optical thickness of the upper layer appears to lie in the range 0.1 to 0.2. The CH4/H2 mixing ratio in the lower layer is larger than the corresponding solar value by a factor on the order of three or greater. The results are discussed briefly in terms of current models of the Uranus atmosphere.

Price, M. J.↗
NASA NTRS1977

Detection and interpretation of ocean roughness variations across the Gulf Stream inferred from radar cross section observations

Radar cross section data shows that the Gulf Stream has a higher cross section per unit area (interpreted here as a greater roughness) than the water on the continental shelf. A steep gradient in cross section was often seen at the expected location of the western boundary. There were also longer-scale (10-20 km) gradual fluctuations within the stream of significant magnitude. These roughness variations are correlated with the surface shear stress that the local wind imposes on the sea. Using the available surface-truth information concerning the wind speed and direction, an assumed Gulf Stream velocity profile, and high-resolution ocean-surface temperature data obtained by the VHRR onboard a NOAA-NESS polar-orbiting satellite, the present study demonstrates that the computed surface stress variation bears a striking resemblance to the measured radar cross-section variations.

Weissman, D. E.↗
NASA NTRS1978

An interpretation of special and general isotopic anomalies in r-process nuclei

My analysis of new discoveries by McCulloch and Wasserburg of Ba and Nd isotopic anomalies in inclusions of the Allende meteorite argues that (1) these anomalies contain special extinct radioactivities resulting from radioactive decay within grains formed in and ejected from the supernova interior, (2) the inclusions studied are fused assemblies of interstellar grains that were never totally vaporized, and (3) theoretical separation into r and s abundances suggests that fluctuations between r and s components has occurred during the accumulation processes. These points lend support to a new chemical picture of the early solar system that I have developed, although many interpretations remain possible. Measurements of the neutron-capture cross sections of Nd isotopes are urgently needed to experimentally validate these conclusions.

Clayton, D. D.↗
NASA NTRS1978

Interpretation of altimeter data

Two methods are used to interpret the whole range of signals contained in the Geos 3 altimeter data. They each address a different class of events and thus complement each other in their ability to provide information on the state of convection in the earth's mantle. The long wavelength section of the spectrum yields information on the depth of convection cells and the viscosity variations inside those cells through a study of the variations of the admittance as a function of wavelength. The short wavelength section of the spectrum provides information on the evolution of the lithosphere, considered as a thin elastic plate, by studying its response to loads at several points in its evolution. The variation of the flexural rigidity with age is obtained from that study.

Roufosse, M. C.↗
NASA NTRS1979

Interpretive computer simulator for the NASA Standard Spacecraft Computer-2 (NSSC-2)

An Interpretive Computer Simulator (ICS) for the NASA Standard Spacecraft Computer-II (NSSC-II) was developed as a code verification and testing tool for the Annular Suspension and Pointing System (ASPS) project. The simulator is written in the higher level language PASCAL and implented on the CDC CYBER series computer system. It is supported by a metal assembler, a linkage loader for the NSSC-II, and a utility library to meet the application requirements. The architectural design of the NSSC-II is that of an IBM System/360 (S/360) and supports all but four instructions of the S/360 standard instruction set. The structural design of the ICS is described with emphasis on the design differences between it and the NSSC-II hardware. The program flow is diagrammed, with the function of each procedure being defined; the instruction implementation is discussed in broad terms; and the instruction timings used in the ICS are listed. An example of the steps required to process an assembly level language program on the ICS is included. The example illustrates the control cards necessary to assemble, load, and execute assembly language code; the sample program to to be executed; the executable load module produced by the loader; and the resulting output produced by the ICS.

Smith, R. S.↗
NASA NTRS1979

Length and bursting of separation bubbles: A physical interpretation

A physical interpretation of the observed form of the pressure distribution beneath a two-dimensional separation bubble which modified the external inviscid pressure distribution only locally is given in terms of boundary layer concepts. A simple method for estimating along a mean streamline entrained into the underside of a growing shear layer through the transition region is discussed, and predictions of bubble bursting conditions and a lower bound on the bubble length are compared with experiment.

Russell, J. M.↗