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LDEF attitude measurement using a pinhole camera with a silver/oxygen atom detectorA small device designed to measure the orbital attitude stability of the Long Duration Exposure Facility (LDEF) spacecraft is examined. The device used the reaction of Ag with O atoms, which convert the metal to a nonconducting black appearing oxide with high efficiency. The atmosphere at LDEF altitudes consists of more than 90 pct. atomic O. The device is a small hemispheric Ag surface facing a pinhole in a metal plate on the front surface of the satellite. It was expected that the stream of O atoms, travelling at a relatively velocity of 8 km/s would pass through the pinhole and strike the Ag surface at the geometric center, producing a circular black spot. In fact, the position of the spot has clearly shown that the LDEF was rotated by 8.0 + or - 0.4 deg from its nominal attitude, but that it was remarkably stable about this offset. The ellipticity of the recorded spot was attributed to a yaw oscillation of + or - 0.2 deg, however it was previously noted, that the co-rotation of the Earth's atmosphere should produce a sweeping of the atom beam vector of ca. + or - 1.5 deg about the surface normal. Such an effect was not visible in this experiment.
Document ID
Document Type
Conference Paper
Gregory, John C.
(Alabama Univ. Huntsville., United States)
Peters, P. N.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1991
Publication Information
Publication: NASA, Langley Research Center, First LDEF Post-Retrieval Symposium Abstracts
Subject Category
Instrumentation And Photography
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.

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