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  • 1
    Publication Date: 2019-06-27
    Description: New 3.5-cm radio and 69-micron far-infrared maps of M17, both made with an angular resolution of about 1.5 arcmin, are presented. Each map has three distinct maxima. Two of the maxima on the far-IR map agree in position with the corresponding maxima on the radio map. However, the positions of the brightest peak in the radio and far-infrared maps, located in the SW part of M17, differ by 4.6 + or - 2.2 s in right ascension and +44 + or - 20 sec in declination, with the far-infrared peak lying between the radio peak and the dense molecular cloud southwest of the H II region. It is believed that the positional offset of the radio and far-infrared peak is physically significant. The origin of the far-infrared radiation appears to be thermal emission from dust at the interface of the ionized gas and molecular cloud. This interface region is probably heated by radiation from the H II region.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 76; 1, Ju; June 197
    Format: text
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  • 2
    Publication Date: 2019-06-27
    Description: A user's manual which describes input/output routines and recommended operating procedures relating to MAPSEP is presented. Samples runs are included.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-143935
    Format: application/pdf
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  • 3
    Publication Date: 2019-06-27
    Description: The mission analysis program for solar electric propulsion (MAPSEP) is comprised of the basic modes: TOPSEP (trajectory generation), GODSEP (linear error analysis), and SIMSEP (simulation). The program is designed to analyze any low thrust mission with respect to trajectory performance, guidance and navigation, and to provide system related requirements for the purpose of vehicle design. The MAPSEP organization is described along with all models and algorithms. Topics discussed include: trajectory and error covariance propagation methods, orbit determination processes, thrust modeling, and trajectory correction (guidance) schemes.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-143934
    Format: application/pdf
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  • 4
    Publication Date: 2019-06-27
    Description: The internal structure of MAPSEP is described. Topics discussed include: macrologic, variable definition, subroutines, and logical flow. Information is given to facilitate modifications to the models and algorithms of MAPSEP.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-143936
    Format: application/pdf
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  • 5
    Publication Date: 2019-07-13
    Description: Small-signal modeling techniques are used in a system stability analysis of a breadboard version of a complete functional electrical power system. The system consists of a regulated switching dc-to-dc converter, a solar-cell-array simulator, a solar-array EMI filter, battery chargers and linear shunt regulators. Loss mechanisms in the converter power stage, including switching-time effects in the semiconductor elements, are incorporated into the modeling procedure to provide an accurate representation of the system without requiring frequency-domain measurements to determine the damping factor. The small-signal system model is validated by the use of special measurement techniques which are adapted to the poor signal-to-noise ratio encountered in switching-mode systems. The complete electrical power system with the solar-array EMI filter is shown to be stable over the intended range of operation.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: PESC ''80; Power Electronics Specialists Conference; Jun 16, 1980 - Jun 20, 1980; Atlanta, GA
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  • 6
    Publication Date: 2019-06-28
    Description: A series of far-infrared maps obtained on the KAO find the total IR luminosity of NGC 2024 is to the 4th power L, and show a peak in flux density and optical depth about 1' south of IRS 2. High resolution spectra of IRS 2 in Brackett alfa and Pfund gamma indicate the presence of an optically thick wind with M approx. 7 x 10 to the minus 7 power M sub yr to minus 1 power, from which we infer that IRS 2 is unable to supply the luminosity observed. A six centimeter continuum map peaks near the location of the far-infrared peak and confirms it as a likely site for a source to provide this luminosity. Maps in HCN, CS, and H2CO show the gas is dense in the direction of the far IR peak. Velocity analysis shows the H2 region created by the far IR source and IRS 2 forms an expanding bubble in front of which the H2CO is seen in absorption, and which is bounded in the south and behind by dense material.
    Keywords: ASTRONOMY
    Type: NASA. Ames Research Center Airborne Astron. Symp.; p 164-171
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  • 7
    Publication Date: 2019-07-13
    Description: The present conference on physics and astrophysics from a lunar base encompasses space physics, cosmic ray physics, neutrino physics, experiments in gravitation and general relativity, gravitational radiation physics, cosmic background radiation, particle astrophysics, surface physics, and the physics of gamma rays and X-rays. Specific issues addressed include space-plasma physics research at a lunar base, prospects for neutral particle imaging, the atmosphere as particle detector, medium- and high-energy neutrino physics from a lunar base, muons on the moon, a search for relic supernovae antineutrinos, and the use of clocks in satellites orbiting the moon to test general relativity. Also addressed are large X-ray-detector arrays for physics experiments on the moon, and the measurement of proton decay, arcsec-source locations, halo dark matter and elemental abundances above 10 exp 15 eV at a lunar base.
    Keywords: ASTRONOMY
    Type: NASA Workshop; May 19, 1989 - May 20, 1989; Stanford, CA; United States
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