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  • Other Sources  (5)
  • 1
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    Sunward spike and equatorial plane of Halley's Comet (1986)
    In:  Other Sources
    Details
    Publication Date: 2013-08-29
    Description: Photographs from late April until at least early June 1986 of comet Halley show a narrow spike in the Sun's direction. It extends to distances of at least 700,000 km from the nucleus in projection onto the sky on computer processed photographs. The spike is composed of dust and its enormous sunward extent (compared to other dust features) suggests an anomalously high ratio of particle ejection velocity to solar radiation pressure. The implied grains are either dielectric or slightly absorbing and much less than 1 micron in size, which are undetectable optically, unless Earth is located in or very near a plane of their concentration. The only plane to which these grains can possibly be confined for long is the equatorial plane of the nucleus, especially when the obliquity is small. Accordingly, the spike's position as a function of time contains information on the comet's spin axis.
    Keywords: ASTROPHYSICS
    Type: ESA Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. Volume 2: Dust and Nucleus; p 177-181
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Internal electrostatic discharge hazard risk assessment to the Galileo orbiter (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A worst case assessment was performed on the Command Data System (CDS) multilayer printed circuit board and an output power transformer module in the power subsystem. An estimate of the Jovian environment during the 35 hour orbit insertion was supplied by JPL and used as an input to calculate the electron transport into the Galileo components. A radiation shielding analysis computer code, CHARGE, calculated the electron transport deposition trapped in the anticipated sensitive areas of the multilayer board and transformer module. Based on these trapped charge calculations electric fields were calculated between the identified isolated areas and the spacecraft ground. The results of the assessment of electrostatic discharge (DSD) in the CDS multilayer printed circuit board indicate that the probability of ESD in the FR4 is low. The probability of ESD in the components attached to the multilayer board, however, is uncertain based on a lack of prior experimental data.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: NASA-CR-163930
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Radiation hardening design of nuclear powered spacecraft (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The design and operation of space systems utilizing nuclear fueled power systems must consider the radiation environment from the earliest stages of their design. A range of nuclear systems are being considered for present and future satellite systems capable of supplying tens of kilowatts to multimegawatt and generating a corresponding range of radiation environments. The effects of these radiations on electronics and materials can be minimized by implementing early design considerations which maximize the design efficiency and minimize the impact on system mass. Space systems design considerations for the radiation environment must include all sources in addition to the self induced gamma ray and neutron radiation. These include the orbital dependent environment from the high energy electron and protons encountered in natural space. The system trades which the designer must consider in the development of space platforms which utilize nuclear reactor power supplies are discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: New Mexico Univ., Transactions of the Fourth Symposium on Space Nuclear Power Systems; p 261-262
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Charging control techniques (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Transparent conductive thin films of indium oxide and indium-tin oxide were evaluated for their properties to control charge buildup on satellite materials. Both oxide coatings were evaluated for their uniformity, stability, reproducibility and characteristics on various substrate materials such as FEP Teflon, Kapton, and glass. The process development toward optimization and characterization of these thin semiconductor oxide coatings and the evaluation on large sizes performed for qualification for use on thermal control satellite materials is described. The materials have been characterized in multiple energy electron plasma environment and at low temperatures. All radiation measurements of the coatings under simulated substorm conditions have exhibited the characteristics of stable charge control. Measurement of surface potential during and after irradiation by electrons up to 30 KeV and ionizing gamma radiation show an effective stable grounding surface.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Research Center Spacecraft Charging Technol., 1980; p 267-286
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    NASA TECHNICAL REPORTS
  • 5
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    Materials and techniques for spacecraft static charge control 2 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Results of exploratory development on the design, fabrication and testing of transparent conductive coatings, conductive bulk materials and grounding techniques for application to high resistivity spacecraft dielectric materials to obtain control of static charge buildup are presented. Deposition techniques for application of indium oxide, indium/tin oxide and other metal oxide films on Kapton, FEP Teflon, OSR and solar cell coverglasses discussed include RF and Magnetron sputtering and vapor deposition. Development, fabrication and testing of conductive glass tiles for OSR and solar cell coverglass applications is discussed. Several grounding techniques for rapid charge dissipation from the conductively coated polymer and glass dielectrics which were developed and tested in thermal cycled and electron plasma environments are described. The optical and electrical characterization and aging effects of these coatings, bulk materials and grounding techniques are reviewed as they apply to the performance of their design functions in a geosynchronous orbit environment.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Res. Center Spacecraft Charging Technol., 1978; p 524-553
    Format: text
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    NASA TECHNICAL REPORTS
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