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  • 1
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    Prospecting for Martian Ice (2005)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: During high Martian obliquity, ice is stable to lower latitudes than predicted by models of present conditions and observed by the Gamma Ray Spectrometer (approx. 60 deg N). An ice-rich layer deposited at mid-latitudes could persist to the present day; ablation of the top 1 m of ice leaving a thin insulating cover could account for lack of its detection by GRS. The presence of an ice-layer in the mid-latitudes is suggested by a network of polygons, interpreted as ice-wedge cracks. This study focuses on an exceptional concentration of polygons in Western Utopia (section of Casius quadrangle, roughly 40 deg - 50 deg N, 255 deg - 300 deg W). We attempt to determine the thickness and age of this ice layer through crater-polygons relations.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Lunar and Planetary Science XXXVI, Part 13; LPI-Contrib-1234-Pt-13
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Improved fabrication techniques for infrared bolometers (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Techniques are described for producing improved infrared bolometers from doped germanium. Ion implantation and sputter metalization have been used to make ohmic electrical contacts to Ge:Ga chips. This method results in a high yield of small monolithic bolometers with very little low-frequency noise. When one of these chips is used as the thermometric element of a composite bolometer, it must be bonded to a dielectric substrate. The thermal resistance of the conventional epoxy bond has been measured and found to be undesirably large. A procedure for soldering the chip to a metalized portion of the substrate is described which reduced this resistance. The contribution of the metal film absorber to the heat capacity of a composite bolometer has been measured. The heat capacity of a NiCr absorber at 1.3 K can dominate the bolometer performance. A Bi absorber has significantly lower heat capacity. A low temperature blackbody calibrator has been built to measure the optical responsivity of bolometers. A composite bolometer system with a throughput of approx. 0.1 sr sq cm was constructed using the new techniques. In negligible background it has an optical NEP of 3.6 10((exp -15) W/sq root of Hz at 1.0 K with a time constant of 20 ms. The noise in this bolometer is white above 2.5 Hz and is somewhat below the value predicted by thermodynamic equilibrium theory. It is in agreement with calculations based on a recent nonequilibrium theory.
    Keywords: OPTICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 24 p
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    A high resolution gamma-ray and hard X-ray spectrometer (HIREGS) for long duration balloon flights (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The elements of a high resolution gamma-ray spectrometer, developed for observations of solar flares, are described. Emphasis is given to those aspects of the system that relate to its operation on a long duration balloon platform. The performance of the system observed in its first flight, launched from McMurdo Station, Antarctica on 10 January, 1992, is discussed. Background characteristics of the antarctic balloon environment are compared with those observed in conventional mid-latitude balloon flights and the general advantages of long duration ballooning are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: EUV, X-ray, and gamma-ray instrumentation for astronomy III; Proceedings of the Meeting, San Diego, CA, July 22-24, 1992 (A93-29476 10-35); p. 408-421.
    Format: text
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  • 4
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    Improved fabrication techniques for infrared bolometers (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Ion implantation and sputter metallization are used to produce ohmic electrical contacts to Ge:Ga chips. The method is shown to give a high yield of small monolithic bolometers with very little low-frequency noise. It is noted that when one of the chips is used as the thermometric element of a composite bolometer it must be bonded to a dielectric substrate. The thermal resistance of the conventional epoxy bond is measured and found to be undesirably large. A procedure for soldering the chip to a metallized portion of the substrate in such a way as to reduce this resistance is outlined. An evaluation is made of the contribution of the metal film absorber to the heat capacity of a composite bolometer. It is found that the heat capacity of a NiCr absorber at 1.3 K can dominate the bolometer performance. A Bi absorber possesses significantly lower heat capacity. A low-temperature blackbody calibrator is built to measure the optical responsivity of bolometers. A composite bolometer system with a throughput of approximately 0.1 sr sq cm is constructed using the new techniques. The noise in this bolometer is white above 2.5 Hz and is slightly below the value predicted by thermodynamic equilibrium theory.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 4; Sept
    Format: text
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  • 5
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    AUTOSIM: An automated repetitive software testing tool (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: AUTOSIM is a software tool which automates the repetitive run testing of software. This tool executes programming tasks previously performed by a programmer with one year of programming experience. Use of the AUTOSIM tool requires a knowledge base containing information about known faults, code fixes, and the fault diagnosis-correction process. AUTOSIM can be considered as an expert system which replaces a low level of programming expertise. Reference information about the design and implementation of the AUTOSIM software test tool provides flowcharts to assist in maintaining the software code and a description of how to use the tool.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-CR-177930 , NAS 1.26:177930
    Format: application/pdf
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