Discovery of BE-7 Accretion in Low Earth Orbit: Annual AAS Guidance and Control Conference (14th) Held in Keystone, Colorado on 2-6 February 1991

We observed strong 7Be activity on the surface of the Long Duration Exposure Facility (LDEF) during the first complete gamma-ray survey of a large spacecraft after its return to earth. This is the first known evidence for accretion of a radioactive isotope onto an orbiting spacecraft. 7Be is produce...

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Bibliographische Detailangaben
Hauptverfasser:	PHillips, G W, King, S E, August, R A, Ritter, J C, Cutchin, J H
Format:	Report
Sprache:	eng
Schlagworte:	ACTIVATION Astronautics BERYLLIUM CONTROL COSMIC RAYS EARTH ORBITS EXPOSURE(GENERAL) FACILITIES GAMMA RAYS ISOTOPE EFFECT ISOTOPES LDEF(LONG DURATION EXPOSURE FACILITY) LONG RANGE(TIME) LOW ALTITUDE LOW ORBIT TRAJECTORIES NITROGEN ORBITS OXYGEN PRODUCTION RADIOACTIVE ISOTOPES SPACE ENVIRONMENTS SPACECRAFT SPALLATION SURVEYS SYMPOSIA UPPER ATMOSPHERE
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Zusammenfassung:	We observed strong 7Be activity on the surface of the Long Duration Exposure Facility (LDEF) during the first complete gamma-ray survey of a large spacecraft after its return to earth. This is the first known evidence for accretion of a radioactive isotope onto an orbiting spacecraft. 7Be is produced by spallation reactions of cosmic rays on nitrogen and oxygen in the upper atmosphere. However, the observed density is much greater than expected due to cosmic ray production in situ; this is significant for models of atmospheric mixing. 7Be may be a valuable tracer in future studies of the upper atmosphere. Other isotopes seen during the survey, the strongest being 22Na, are due to activation of spacecraft components while in orbit. We discuss the likely accretion of other cosmic-ray produced isotopes and their possible effects on spacecraft in low-earth orbit.