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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Lunar Orbiter photo-subsystem mechanisms

Lunar Orbiter photo subsystem mechanisms, discussing film transport, vacuum and mechanical clamps, focal plane shutter, processor-dryer and optical mechanical scan

Bradley, G.↗
NASA NTRS1972

An Analysis of Texture on Lunar Ground Photos

An experiment was performed in an attempt to evaluate autocorrelation as an indicator of texture using five small patches representing varying distances on each of four lunar photos. Each patch was scanned at 50 micron increments on a 64-level gray scale. Several problems were involved in using the ordinary autocorrelation value but a rougher autocorrelation measure, the percentage of neighboring pairs (at a given lag distance) which fell within one graylevel of one another, yielded very encouraging results. As the distance to the feature decreased, initial slope of the graph of percentage against lag increased, and the general level of the graph decreased. When a crestline was present, the graph tended to continue to decrease at higher lags as well, rather than leveling off after the initial steep slope.

Olson, J. M.↗
NASA NTRS1972

Photogrammetry and photo interpretation applied to analyses of cloud cover, cloud type, and cloud motion

A determination was made of the areal extent of terrain obscured by clouds and cloud shadows on a portion of an Apollo 9 photograph at the instant of exposure. This photogrammetrically determined area was then compared to the cloud coverage reported by surface weather observers at approximately the same time and location, as a check on result quality. Stereograms prepared from Apollo 9 vertical photographs, illustrating various percentages of cloud coverage, are presented to help provide a quantitative appreciation of the degradation of terrain photography by clouds and their attendant shadows. A scheme, developed for the U.S. Navy, utilizing pattern recognition techniques for determining cloud motion from sequences of satellite photographs, is summarized. Clouds, turbulence, haze, and solar altitude, four elements of our natural environment which affect aerial photographic missions, are each discussed in terms of their effects on imagery obtained by aerial photography. Data of a type useful to aerial photographic mission planners, expressing photographic ground coverage in terms of flying height above terrain and camera focal length, for a standard aerial photograph format, are provided. Two oblique orbital photographs taken during the Apollo 9 flight are shown, and photo-interpretations, discussing the cloud types imaged and certain visible geographical features, are provided.

Larsen, P. A.↗
NASA NTRS1973

Analysis of photo linear elements, Laramie Mountains, Wyoming

The author has identified the following significant results. Photo linear features in the Precambrian rocks of the Laramie Mountains are delineated, and the azimuths plotted on rose diagrams. Three strike directions are dominant, two of which are in the northeast quadrant. Laramide folds in the Laramie basin to the west of the mountains appear to have the same trend, and apparently have been controlled by response of the basement along fractures such as have been measured from the imagery.

Blackstone, D. L., Jr.↗
NASA NTRS1973

Geology of photo linear elements, Great Divide Basin, Wyoming

The author has identified the following significant results. Ground examination of photo linear elements in the Great Divide Basin, Wyoming indicates little if any tectonic control. Aeolian aspects are more widespread and pervasive than previously considered.

Blackstone, D. L., Jr.↗
NASA NTRS1973

The electric field in the vicinity of a photo-emitting plate in a plasma

Knowledge of the electric field in the vicinity of a spacecraft provides necessary corrections to measurements of ambient fields and charged particle fluxes and a required parameter to understand the motion of dust particles and grains around the spacecraft. The complex problem of the entire electric field, needed for grain transport calculations, is treated for the one-dimensional case. By approximations to the analysis of a photo-emitting plate immersed in a dilute plasma, explicit expressions for the potential and the electric field were derived. The two classes of implicit solutions for the potential reported by them are shown to yield essentially identical results for the conditions in our solar system. The values were obtained following assumptions of a later paper by Guernsey and Fu, in which the emitted photoelectron distribution is taken as Maxwellian. These results are compared with a simple model due to Grand and Tunaley, wherein the effect of the dilute plasma is neglected entirely.

Barengoltz, J.↗
NASA NTRS1976

Vulcanism, mercury-sensitized photo-reactions and abiogenetic synthesis - A theoretical treatment

Attention is called to the photodynamic and thermodynamic properties of Periodic Group IIb elements, most notably Hg, as they relate to ultra-violet sensitization in organic chemical reactions. The energy levels of 6 1P1 and 6 3P1 resonance states and the high vapor pressure (greater than 0.001 mm) of the metal at temperatures as low as 293 K bring Hg with the range of bond dissociation energies in most organic molecules and many inorganics. These capabilities considered together with recent evidence for Hg emission as a regular part of volcanic and geothermal processes provide the basis for a proposal that Hg-sensitized ultraviolet photo-reactions may have played a significant part in abiogenetic organic synthesis on the primative earth.

Siegel, S. M.↗
NASA NTRS1977

Photo sensor array technology development

The development of an improved capability photo sensor array imager for use in a Viking '75 type facsimile camera is presented. This imager consists of silicon photodiodes and lead sulfide detectors to cover a spectral range from 0.4 to 2.7 microns. An optical design specifying filter configurations and convergence angles is described. Three electronics design approaches: AC-chopped light, DC-dual detector, and DC-single detector, are investigated. Experimental and calculated results are compared whenever possible using breadboard testing and tolerance analysis techniques. Results show that any design used must be forgiving of the relative instability of lead sulfide detectors. A final design using lead sulfide detectors and associated electronics is implemented by fabrication of a hybrid prototype device. Test results of this device show a good agreement with calculated values.

Rossman, M. W.↗