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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 91 records · Page 5
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NASA NTRS1977

System implications of large radiometric array antennas

Temperature sensitivity degradation due to antenna losses is recognized as a hindrance to extension of available remote-sensing radiometry techniques to larger systems for enhanced spatial resolution. The use of large antennas is also complicated by difficulties with bandwidth and integration time. Advantages of introducing active devices at the subarray level, with distributed Dicke switching or correlation detection, are examined, and their possible contribution to the design of effective imaging microwave radiometers for remote sensing of geophysical parameters (sea state, distribution of sea ice, cloud types and their distributions, soil moisture) is assessed.

Levis, C. A.↗
NASA NTRS1977

Remote sensing techniques applied to multispectral recognition of the Aranjuez pilot zone

A rectangular (7 x 14 km) area 40 km S of Madrid was remote-sensed with a three-stage recognition process. Ground truth was established in the first phase, airborne sensing with a multispectral scanner and photographic cameras were used in the second phase, and Landsat satellite data were obtained in the third phase. Agronomic and hydrological photointerpretation problems are discussed. Color, black/white, and labeled areas are displayed for crop recognition in the land-use survey; turbidity, concentrations of pollutants and natural chemicals, and densitometry of the water are considered in the evaluation of water resources.

Lemos, G. L.↗
NASA NTRS1976

Ages of flow units in the lunar nearside maria based on Lunar Orbiter IV photographs

A map dividing the lunar nearside maria into six units each of uniform age was compiled from Lunar Orbiter IV photographs. Relative ages were determined using a crater morphology technique. Relative ages were then converted to absolute ages by comparison to a curve calibrated from Apollo and Luna sample data; three of the six units, including the two youngest (about 3.1 and 2.6 b.y. old), were not sampled by Apollo or Luna. Vast regions in the western maria are covered by these young flows. The old flows (about 3.75 b.y. in age) are found to occur mostly in the eastern maria. A comparison of the age units derived from these data with those units derived from other remote-sensing data provide good agreement in the location of unit boundaries. These data also indicate that the emplacement history of mare basalt types is more complex than was earlier thought.

Boyce, J. M.↗
NASA NTRS1977

Ozone monitoring with an infrared heterodyne radiometer

Measurements of the total burden and of the concentration-versus-altitude profiles of ozone have been made with a ground-based heterodyne radiometer at Pasadena, California. The measurements were made in the 9.5-micron wavelength region, where a strong ozone infrared absorption band exists. The radiometer measured solar absorption at selected wavelengths with a spectral resolution of 0.001 reciprocal centimeter, equivalent to the half-width of an ozone absorption line at the 10-millibar altitude level. A carbon dioxide laser served as the local oscillator. This technique can be used to gather important data on both tropospheric and stratospheric ozone, which are not readily accessible with other remote-sensing techniques.

Menzies, R. T.↗
NASA NTRS1976

Applications of remote sensing data in Alaska: A cooperative program of the University of Alaska with user organizations, including local, state and federal government agencies

The development of the coastal-zone-related issues is generating an increasing need for information which is greater in quantity of natural resource data, greater in quality of detail of data, and more frequent in collection of data owing to the need to monitor certain aspects of programs. The array, detail, and frequency of information acquisition required to develop natural resources and to implement and maintain the resulting programs demand improved techniques of data gathering, processing, and interpretation which is conducive to the use of remote-sensing techniques. As Alaska, both in the state and federal domain, gears up to meet the energy-related issues facing the nation there will be a growing role for efforts which adapt state-of-the-art tools to solving existing problems.

Miller, J. M.↗
NASA NTRS1977

Instrumental sensing of stationary source emissions

A variety of programs have been conducted within EPA to evaluate the capability of various ground-based remote-sensing techniques for measuring the SO2 concentration, velocity, and opacity of effluents from coal-burning power plants. The results of the remote measurements were compared with the results of instack measurements made using EPA reference methods. Attention is given to infrared gas-filter correlation radiometry for SO2 concentration, Fourier-transform infrared spectroscopy for SO2 concentration, ultraviolet matched-filter correlation spectroscopy for SO2 concentration, infrared and ultraviolet television for velocity and SO2 concentration, infrared laser-Doppler velocimetry for plume velocity, and visible laser radar for plume opacity.

Herget, W. F.↗
NASA NTRS1977

Mars surface properties observed by earth-based radar at 70-, 12.5-, and 3.8-cm wavelengths

In the present paper, the results are summarized of a study aimed at determining the small-scale surface properties of Mars (for the Viking project) from a thorough review of all available Martian radar data for the 1973 opposition. Analysis of the quasi-specular echo component showed changes in apparent reflectivity of at least 5 to 1. If attributed entirely to variations in surface material, these correspond to dielectric constants between 1.6 and 4.0. Values of rms surface slope on 1- to 100-m scales range from as low as 0.5 degrees in tablelands near Valles Marineris to more than 3.0 degrees in certain other areas. There is a weak correlation between the small-scale surface characteristics inferred from radar and those inferred from Mariner 9 images and other remote-sensing data sets.

Simpson, R. A.↗
NASA NTRS1976

Hydrographic charting from Landsat satellite - A comparison with aircraft imagery

The relative capabilities of two remote-sensing systems in measuring depth and, consequently, bottom contours in sandy-bottomed and sediment-laden coastal waters were determined quantitatively. The Multispectral Scanner (MSS), orbited on the Landsat-2 satellite, and the Ocean Color Scanner (OCS), flown on U-2 aircraft, were used for this evaluation. Analysis of imagery taken simultaneously indicates a potential for hydrographic charting of marine coastal and shallow shelf areas, even when water turbidity is a factor. Several of the eight optical channels examined on the OCS were found to be sensitive to depth or depth-related information. The greatest sensitivity was in OCS-4 (0.544 plus or minus 0.012 micron) from which contours corresponding to depths up to 12 m were determined. The sharpness of these contours and their spatial stability through time suggests that upwelling radiance is a measure of bottom reflectance and not of water turbidity. The two visible channels on Landsat's MSS were less sensitive in the discrimination of contours, with depths up to 8 m in the high-gain mode (3 X) determined in MSS-4 (0.5 to 0.6 micron).

Middleton, E. M.↗
NASA NTRS1977

Interpretations of optical observations of Mercury and the moon

Optical, thermal and radar remote-sensing measurements indicate that Mercury is covered with a relatively thick layer of soil similar in texture and thickness to lunar regolith. Photometric limb profiles measured by Mariner 10 imply that the small-scale slopes on Mercury are about half those on the moon, probably because of differing gravity. The differential photometric functions of Mercury and the moon have a latitudinal dependence which can be completely accounted for by shadowing in craters. The lack of polar darkening on Mercury in spite of the presence of a magnetic field implies that the dominant soil-darkening process on Mercury, and by extension, on the moon is not dependent on the solar wind, but probably is deposition of material evaporated by meteorite impacts. Recent measurements of Mercury's spectral reflectivity in the IR and vacuum UV are both consistent with the surface rocks of Mercury being lower in FeO than those of the moon. Based on laboratory experiments the average FeO content on the surface of Mercury is estimated to be between 3 and 6%.

Hapke, B.↗
NASA NTRS1977

Parametric design of ground data processing/support systems for advanced sensor systems

A parametric system design technique has been applied to ground data processing/support systems for advanced sensor applications. The system establishes a direct link between budget analysts and system planners. Three primary phases are identified: the definition of requirements, system design, and system costing. The system is evaluated for three cases: (1) a study of ground data handling systems for earth resource satellites, (2) a ground data mass storage and processing system for agricultural remote-sensing studies, and (3) a parametric study of shuttle era data processing support required for atmospheric and space physics.

Denny, C.↗
NASA NTRS1977

Temperature dependence of Fe/++/ crystal field spectra - Implications to mineralogical mapping of planetary surfaces

Results are reported of Fe(++) crystal field spectral measurements for olivines and pyroxenes up to 400 C. The results are correlated with crystal structure data at elevated temperatures, and the validity of remote-sensed identifications of minerals on hot surfaces of the moon and Mercury is assessed. Two techniques were used to obtain spectra of minerals at elevated temperatures using a spectrophotometer. One employed a diamond cell assembly or a specially designed sample holder to measure polarized absorption spectra of heated single crystals. For the other technique, a sample holder was designed to attach to a diffuse reflectance accessory to produce reflectance spectra of heated powdered samples. Polarized absorption spectra of forsterite at 20-400 C are shown in a graph. Other graphs show the temperature dependence of Fe(++) crystal field bands in olivines, the diffuse reflectance spectra of olivine at 40-400 C, the polarization absorption spectra of orthopyroxene at 30-400 C, the diffuse reflectance spectra of pigeonite at 40-400 C, and unpolarized absorption spectra of lunar pyroxene from Apollo 15 rock 15058.

Sung, C.-M.↗
NASA NTRS1979

An assessment of near-earth asteroid resources

On the basis of remote-sensing evidence and meteorite studies, a substantial fraction of small asteroids in near-earth space should contain abundant volatile (water, carbon, carbon compounds) and/or free metal (nickel-iron) materials. Although there are only about 40 known earth-approaching asteroids, this number could be increased by at least an order of magnitude in a few years by a dedicated search program with a large telescope (48 in. Schmidt). A discovery rate of 20 objects/yr could be expected from a facility costing about $3 million to establish. Relatively high-resolution, broad-wavelength coverage reflectance spectra could be made for many of these objects with a large telescope and instruments under development. Such spectra are necessary for detailed mineralogic, characterizations of these asteroids. Low-resolution survey survey spectra with similar wavelength coverage (UBVRIJHK filters) would provide useful characterizations of fainter objects.

Gaffey, M. J.↗
NASA NTRS1977

Optical polarimetry of particulate surfaces

Reflection polarimetry is a remote-sensing tool sensitive to the refractive index and microtexture of solid surfaces. Mechanisms producing linear polarization within a rough, porous, or particulate surface are discussed, and laboratory techniques for precise measurements are described in some detail. Polarimetry of atmosphereless solar-system bodies provides valuable indications of albedo for objects too small and distant for direct diameter determinations, and reveals that even quite small asteroids and satellites have particulate surfaces

Zellner, B.↗
NASA NTRS1978

Pressure sensing of the atmosphere by solar occultation - An application to remote sensing of atmospheric minor gases

The simultaneous inference of pressure and gas concentration in a remote-sensing experiment will increase the accuracy of inverted gas concentrations and minimize the dependence of the experiment on pressure or mass-path error resulting from use of climatological pressure data, satellite ephemeris, and instrument pointing accuracy. A technique for obtaining tangent-point pressure information needed for inversion of gas concentration in an IR solar occultation experiment is described. By measuring IR absorption in bands of atmospheric CO2 (e.g., 2.0, 2.7, or 4.3 microns) pressure values for each layer (2 km or less in the vertical) of the atmosphere can be obtained with rms errors of less than 3%.

Park, J. H.↗
NASA NTRS1978

A microwave radiometer spacecraft

A conceptual design for a future microwave-radiometer spacecraft is described. The intended remote-sensing mission is centered around soil moisture measurements and requires all-weather day and night observations at a low microwave frequency (less than 5 GHz) in order to penetrate clouds, haze, and ground covers. The specific mission requirements are summarized in terms of two broad mission objectives, the system design requirements are outlined, and three structural approaches are evaluated at the conceptual design level. The weights, Shuttle flights, and structural member lengths for the three concepts are compared. The dual momentum vector control concept for pointing and slewing control is examined.

Lovelace, U. M.↗
NASA NTRS1978

Infra-red measurements of stratospheric composition. I - The balloon instrument and water vapour measurements

The design and construction of a balloon-borne instrument for remote-sensing of stratospheric composition is described. Thermal emission from the constituents is detected and the spectral selectivity of the instrument is tailored to a specific gas by the use of a cell of the same gas in the optical path of the radiometer. The pressure of the gas in the cell is cycled and the resultant transmission function is shown to be highly selective to radiation from the same gas in the atmosphere. The first flight of the instrument and the retrieval of a water vapour profile in the range 15-40 km is described.

Chaloner, C. P.↗
NASA NTRS1978

Reflectance measurements of lunar materials in the vacuum ultraviolet

The spectral reflectances of materials have been measured in the vacuum ultraviolet region of the spectrum for possible planetary compositional remote-sensing applications. These materials, which include lunar and terrestrial silicate rocks and minerals, have one or more characteristic absorption peaks between about 8 and 13 eV. The peaks are visible in the spectra of powders and rough surfaces as well as polished surfaces. In lunar samples the most prominent peaks are at 10.25 eV, due to augite, and at 9.0 eV, due to anorthite. Spectra of lunar soils have minima between 6 eV (0.20 micron) and 8 eV (0.16 micron) depending on composition. Soils that have high reflectances in the visible have low reflectances in the VUV. The pyroxene content of the soils results in reflectance maxima at about 10 eV (0.12 micron). Peaks due to olivine and augite can be identified in the spectra of meteorites.

Hapke, B. W.↗
NASA NTRS1979

Cost and performance characteristics of data system configurations for processing remotely sensed data

Some alternative approaches to constructing a large remote-sensing data system are explored. The cost and performance implications of using a collection of 'small' computers versus using one large computer are examined. Several architectures and associated costs for the large data system supporting a single data center are presented. Recurring cost factors (maintenance and operations) currently slightly favor the single large-machine architecture, but other factors may dictate the choice of one of the two multimachine architectures discussed.

Gregor, P. J.↗