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the interactions of atmospheric cosmogenic radionuclides with spacecraft surfacesThe discovery of the cosmogenic radionuclide Be-7 on the front surface of the Long Duration Exposure Facility (LDEF) has opened new opportunities to study several unexplored regions of space science. The experiments have shown that the Be-7 found was concentrated in a thin surface layer of spacecraft material. The only reasonable source of the isotope is the atmosphere through which the spacecraft passed. It is expected that the uptake of Be in such circumstances will depend on the chemical form of the Be and the chemical nature of the substrate. It was found that the observed concentration of Be-7 does differ between metal surfaces and organic surfaces such as PTFE (Teflon). It is noted however, that (1) organic surfaces are etched by the atomic oxygen found under these orbital conditions, and (2) the relative velocity of the species is 8 km/s relative to the surface and the interaction chemistry and physics may differ from the norm. Be-7 is formed by disintegration of O and N nuclei under cosmic ray proton bombardment. Many other isotopes are produced by cosmic ray reactions, and some of these are suited to measurement by the extremely sensitive methods of accelerator mass spectrometry.
Document ID
19910015668
Document Type
Conference Paper
Authors
Gregory, John C.
(Alabama Univ. Huntsville., United States)
Fishman, G. J.
(NASA Marshall Space Flight Center Huntsville, AL., United States)
Harmon, A.
(NASA Marshall Space Flight Center Huntsville, AL., United States)
Parnell, T. A.
(NASA Marshall Space Flight Center Huntsville, AL., United States)
Herzog, G.
(Rutgers Univ. New Brunswick, NJ., United States)
Klein, J.
(Pennsylvania Univ. Philadelphia., United States)
Jull, A. J. T.
(Arizona Univ. Tucson., 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
ATOMIC AND MOLECULAR PHYSICS
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19910015658Analytic PrimaryFirst LDEF Post-Retrieval Symposium abstracts