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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

SIR-B radar imagery of volcanic deposits in the Andes

Synthetic-aperture radar imagery from the Shuttle Imaging Radar - mission B (SIR-B) was collected in October 1984 over the central Andes between 20 deg S and 24 deg S and also south of 42 deg S. Despite signal-strength problems that drastically reduced the signal-to-noise ratio of the images, volcanic features of both areas show up well. In particular, ignimbrite sheets formed by large explosive eruptions stand out as very strong radar reflectors. High backscatter is apparently caused by erosional relief on the ignimbrites at scales ranging from the radar wavelength (23 cm for SIR-B) to the 30-200-m scale of quebradas (gullies and canyons). The consistent regional erosional pattern appears unrelated to the emplacement of the ignimbrites, and is probably caused by preferential eolian erosion in the directions of the prevailing wind. Hand-held space photographs, ground observations, and Landsat Thematic Mapper imagery support the interpretation of the ignimbrite radar signature. The Chilean volcano Michinmahuida was imaged by four radar data takes at different incidence angles, which show tectonic, glacial, and volcanic features of that nearly inaccessible and often cloud-covered region. Stereo viewing of radar images from two data takes greatly enhances the geologic interpretation of this rugged area.

Fielding, E. J.↗
NASA NTRS1973

Interpretation of the Jupiter Red Spot, 1

With the aid of 8900 micron CH4 filter photographs it is shown that the Red Spot is normally the highest cloud feature in the Jovian atmosphere, located squarely on the South Tropical Zone at 22 deg. S. The Red Spot is a rising column, obviously having its own energy source; it spreads outward at the top level, in anticyclonic rotation. It is concluded that the large and persistent Jovian cloud masses, of which the Red Spot is the largest, are major organized storm arrays embedded in a near stagnant atmosphere, each probably possessing numerous short-lived rising hot columns driven by released latent heat; and covered by a horizontally-expanding gigantic cirrus cloud system, in anti-cyclonic rotation. The meteorological theory of Organized Cumulus Convection is applied to the Red Spot and the White Ovals. Evidence exists that the array of hot towers under the Red Spot is eccentric. The 90-day and the occassional 5-8 year fluctuations in the motion of the Red Spot may be due to processes analogous to those found in the Earth's Tropical Convergence. The 90-day oscillation has been observed for 8 years.

Kuiper, G. P.↗
NASA NTRS1981

Theoretical interpretation of photometric properties of the Martian surface and atmosphere

Earth-based UBV photometry, photographs from the Lowell Observatory, and Mariner 9 data are combined with a new radiative transfer theory to derive physical parameters for the Martian surface and atmosphere, both before and during the 1971 dust storm. Storm dust particles had a single scattering albedo of 0.84 plus or minus 0.02 and an asymmetry factor of 0.35 plus or minus 0.10 in green (V) light. The geometric albedo of Mars was 0.15 and the phase integral 1.83, yielding 0.27 for the Bond albedo. The mean optical thickness of the 'clear' atmosphere averaged over the whole planet was 0.15 plus or minus 0.05 and was not dependent on wavelength. Geometric albedos for the surface are 0.25 (light areas) and 0.17 (dark areas) in V, 0.095 in B, and 0.060 in U. The soil particles are moderately backward scattering with an asymmetry factor of minus 0.20, and therefore rather opaque. The mean surface roughness is 0.57, representing the depth/radius ratio of an average hole, and being only one-half as large as values typical for the moon and asteroids.

Lumme, K.↗
NASA NTRS1983

Theoretical interpretation of the ground-based photometry of Saturn's B ring

Small tilt angle photographic photometry obtained during 1979 and 1981 apparitions is combined with previous data to derive physical parameters for the Saturn B ring in red and blue colors. The value of the volume density is 0.020 + or - 0.004, with no indication of dependence on either the color or the tilt for values between 6 and 26 deg. For the geometric albedo of a single particle, the derived values of 0.61 + or - 0.04 in the red and 0.41 + or - 0.03 in the blue are superior to earlier estimates lacking the most recent data. The present results indicate that the ground-based photometry is fully consistent with the classical, many-particle-thick ring model.

Lumme, K.↗
NASA NTRS1981

Shock-associated noise reduction from inverted-velocity-profile coannular jets

The reduction of shock-associated noise in inverted velocity profile coannular jets is investigated and quantified by making optical and acoustic measurements as a function of outer and inner stream pressure ratio combinations and interpreting noise results with the aid of new theoretical models. Schlieren photographs are obtained in three series of test conditions with a varying primary stream pressure ratio, and acoustic experiments are conducted on a polar arc radius of 3.05 m over a frequency range of 200 Hz to 80 kHz. A constant-thrust comparison is made, and data are plotted and discussed with emphasis on the variation of jet noise levels with primary stream Mach number and equivalent single jets on an absolute basis. It is shown that shock noise from the outer stream is almost eliminated when the inner stream is operated at a Mach number above unity at inverted and normal velocity profile conditions, and optical measurements indicate that for a fixed supercritical fan stream pressure ratio, the repetitive shock structure in the outer stream is minimized when the primary stream ratio becomes supercritical.

Tanna, H. K.↗
NASA NTRS1982

The use of large-scale aerial photography for interpreting Landsat digital data in an elk habitat-analysis project

Large-scale aerial photography was used to interpret Landsat multispectral scanner data processed through an unsupervised classifier. After scale adjustment and interpretation by application of an elk-habitat photointerpretation legend, the photographs were registered with the spectral classification, and the co-occurrence of spectral picture elements with photointerpreted habitat classes was tabulated. Analysis of the resulting table of data permitted the description of spectral classes in terms meaningful and useful to elk research and management unit in the Blue Mountains of northeastern Oregon.

Isaacson, D. L.↗
NASA NTRS1982

Desert landforms of southwest Egypt: A basis for comparison with Mars

Geologic interpretations of The Gilf Kebir-Uweinat of Apollo-Soyuz photographs were verified. The photographs and LANDSAT images showed features reminiscent of those depicted by Mariner and Viking missions to Mars. These features were to better understand their morphologic analogs on Mars. It is indicated that climate change played a significant role in the formation of the eastern Sahara. It is also revealed that correlations between the eolian features in southwestern Egypt and the wind blown patterns on the surface of Mars result in a better understanding of eolian activity on both planets.

El-Baz, F.↗
NASA NTRS1998

A Spatial Classifier for Multispectral Data Using Contextual Information

Connectivity describes the spatial relationship among pixels. A spatial classifier which employs the sigma probability concept of the Gaussian distribution and a type of contextual information connectivity of the pixels, is studied in this paper. This spatial classifier attempts to replicate the kind of spatial synthesis done by the human analyst during visual interpretation or to capture the spatial relationships inherent in an aerial photograph. Several classification results of the Landsat TM data using this classifier with different window sizes for capturing the contextual information are illustrated and compared.

Hung, Chih-Cheng↗
NASA NTRS1973

UV photography of the earth and the moon

The fundamental aim of this experiment was the acquisition of ultraviolet photographs of the earth and the moon that could be used to interpret similar imagery of Mars and Venus. Venus shows no markings whatever when viewed in visible light, a phenomenon that is in keeping with its immensely thick atmosphere and perpetual cloud cover, but in the near ultraviolet, the planet exhibits low contrast markings which vary in position and appearance with time. Mars posed just the opposite problem from Venus at wavelengths below 4500 A, Mars shows very little detail, sometimes none at all, whereas at longer wavelengths, the surface is clearly visible. Occasionally observers have reported that this obscuration has lifted and the ground has become visible at the shorter wavelengths as well. Such events have been labeled blue clearings and led to the suggestion that the ultraviolet obscuration was caused by an atmospheric haze. Mariner 6 and 7 observations of Mars failed to find such a haze and lent support to the alternative view that ascribed the absence of detail on UV photographs to a simple lack of contrast between Martian surface features at these wavelengths.

Source record↗
NASA NTRS1975

Calculations for interpretation of solar vector magnetograph data

Computer techniques for data analysis of sunspot observations are presented. Photographic spectra were converted to digital form and analyzed. Methods of determining magnetic field strengths, i.e., the Zeeman effect, are discussed. Errors originating with telescope equipment and the magnetograph are treated. Flow charts of test programs and procedures of the data analysis are shown.

Dunn, A. R.↗
NASA NTRS1972

Heat-transfer testing procedures in phase B shuttle studies with emphasis on phase change data improvement

The procedures used in the application of the phase change technique to the phase B shuttle configuration are discussed along with factors which may affect data accuracy. These factors include variation of thermal properties of phase change model material, sensitivity of measured heat transfer coefficients to the assumed value of the adiabatic to total temperature ratio, and wall temperature effects. These sensitivities are illustrated in sample calculations for a shuttle geometry. Factors which may affect the visual clarity and interpretation of phase change data are discussed, and a method of improving photographic data quality through the use of polarized light is presented.

Throckmorton, D. A.↗
NASA NTRS1980

HCMM imagery for the discrimination of rock types, the detection of geothermal energy sources and the assessment of soil moisture content in western Queensland and adjacent parts of New South Wales and South Australia

Only photographic prints and negative films of day-visible, day-IR and night-IR imagery were received. For northwest Queensland, only five day-visible and day-IR frames of acceptable quality were received. A master-grid was established over these frames within which selected grid sections are being enlarged photographically for the identification of stream courses and geological features permitting an interpretation of the imagery relative to ground truth information. The imagery is also being scanned and digitized using a Joyce-Loebl microdensitometer for classification purposes. For areas for which good quality HCMM imagery is available, valuable information is obtained on ephemeral and seasonal drainage systems. The day-IR cover is particularly helpful.

Cole, M. M.↗
NASA NTRS1980

Possible rim crest deposits in cores 12027 and 15008 - Some interpretations and problems for future research

Light colored coarse grained soils in the upper parts of cores 12027 and 15008 have a chaotic fabric and abundant bedrock-derived rock fragments. They overlie dark colored, fine grained soils with horizontal fabric and abundant regolith-derived rock fragments. The light colored soils are interpreted to be rim crest deposits associated with the craters seen in the lunar surface sampling photographs. The coarse size, poor sorting and chaotic fabric are believed to have originated by the violent mixing processes which are expected with ejecta deposition. The increase in bedrock-derived particles within the light colored soil can be explained by ejecta from craters that penetrated through or deep into the regolith. The dark soils are believed to predate the craters. Distribution of rock fragments in the material interpreted as rim crest ejecta does not fit a simple model of overturned stratigraphy.

Nagle, J. S.↗
NASA NTRS1972

Bonanza project, 1971

Research on the application of remote sensing techniques to the mineral industry stresses photointerpretation by human interpreter experienced in the extraction of geological information from aerial color and multiband photographs and from thermal scanner imagery. Also considered are optical and digital image enhancement, multiband color additive projection, video image processing, and computer reduction and analysis of infrared spectrometry. Evaluation of those parameters which have the most contrast between adjacent rock formations and which can be remotely sensed establish the following most useful geological characteristics: Topographic landform, color, albedo, and surface temperature.

Lee, K.↗
NASA NTRS1972

Photometric studies of Saturn's ring and eclipses of the Galilean satellites

Reliable data defining the photometric function of the Saturn ring system at visual wavelengths are interpreted in terms of a simple scattering model. To facilitate the analysis, new photographic photometry of the ring has been carried out and homogeneous measurements of the mean surface brightness are presented. The ring model adopted is a plane parallel slab of isotropically scattering particles; the single scattering albedo and the perpendicular optical thickness are both arbitrary. Results indicate that primary scattering is inadequate to describe the photometric properties of the ring: multiple scattering predominates for all angles of tilt with respect to the Sun and earth. In addition, the scattering phase function of the individual particles is significantly anisotropic: they scatter preferentially towards the sun. Photoelectric photometry of Ganymede during its eclipse by Jupiter indicate that neither a simple reflecting-layer model nor a semi-infinite homogeneous scattering model provides an adequate physical description of the Jupiter atmosphere.

Brunk, W. E.↗
NASA NTRS1973

Optical scattering properties of Saturn's ring.

Reliable data defining the photometric function of the Saturn ring system at visual (V) wavelengths are interpreted in terms of a simple scattering model. To facilitate the analysis, new photographic photometry of the ring has been carried out utilizing the Lowell observatory plate collection. Homogeneous measurements of the mean surface brightness (rings A and B together), covering almost the complete range in planetocentric solar declination angle, are presented. The ring model adopted is a plane-parallel slab of isotropically scattering particles; the single scattering albedo and the perpendicular optical thickness are both arbitrary. Results indicate that primary scattering is inadequate to describe the photometric properties of the ring; multiple scattering predominates for all angles of tilt with respect to the Sun and Earth.

Price, M. J.↗
NASA NTRS1974

Applications of ERTS data to resource surveys of Alaska

ERTS data affords a unique opportunity to perform urgently needed resource surveys and land use planning at a critical juncture in the history of Alaska's social and economic development. The available facilities for photographic, optical and digital processing of ERTS data are described, along with the interpretive techniques which have been developed. Examples of the applications of these facilities and techniques are given for three environmental disciplines: vegetation mapping for potential archeological sites; marine and sea ice surveys on the Alaskan continental shelf for the determination of surface circulation and sedimentation patterns and their effects on navigation, pollution assessment, fisheries, location of habors and construction of off-shore structures; snow surveys for inventories of water resources and flood potential in Alaska watersheds.

Belon, A. E.↗