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  • 1
    Publikationsdatum: 2013-08-31
    Beschreibung: Except in the near Earth phase of GIOTTO's mission to Comet Halley, the HGA (high gain antenna) on board GIOTTO was the only designed means of up/down communications. The spacecraft spin stabilization required that the HGA be despun at the same rotational rate of nominally 15 rpm in order to keep the HGA pointing accurately to a Earth. A dual servomotor despin mechanism was designed and built by SEP of France for this purpose. The expected thermal environment suggested that dry lubrication was preferable to wet for the ball bearings but there existed no relevant data on the torque noise spectrum of candidate solid lubricants. Therefore ad hoc torque noise tests were run with two solid lubricants: ion plated lead film plus lead bronze cage (retainer) and a PTFE composite cage only. The lead lubrication showed the better spectrum up to the mission lifetime point so it was selected for continued test over some 20 times the Halley mission life, with periodic torque spectrum monitoring. The spectrum remained well within the pointing error budget over the 100 million revolutions covered.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA-Lyndon B. Johnson Space Center, The 21st Aerospace Mechanisms Symposium; p 295-314
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2016-06-07
    Beschreibung: The work performed on thermal vacuum testing of complex mechanisms is described. The objective of these tests is to assess the mechanism reliability by monitoring performance in an environment that closely resembles the environment that will occur during flight. To be both valid and cost effective, these tests are performed in a detailed, formally controlled manner. A review of the major test observations is given, during which time some failure modes are detected. Full confidence now exists in many mechanism and component designs, and much valuable data obtained.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA. Goddard Space Flight Center The 18th Aerospace Mech. Symp.; p 93-109
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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