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Noble gases in ancient asteroidal atmospheresAnalytical and numerical results presented here suggest that acceleration of photoions by the solar wind motional field is a significant loss process for Xe on asteroids about 200 km in radius or larger, if the Xe is thermalized by its interactions with the surface. For Ar, photoion acceleration can only become important for asteroids nearly 500 km in radius. Thus photoion acceleration, previously invoked for lunar samples, could be responsible for excess fission-produced Xe found associated with solar wind Xe in howarditic meteorites. The lack of such Xe in other types of meteorites may reflect either smaller parent bodies or later times of regolith exposure. Similarly, the failure to observe solar-wind-associated radiogenic Ar-40 in meteorites is consistent with the much smaller likelihood that Ar will be photoionized.
Document ID
19940033486
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Swindle, Timothy D.
(Arizona Univ. Tucson, United States)
Date Acquired
August 16, 2013
Publication Date
August 25, 1993
Publication Information
Publication: Journal of Geophysical Research
Volume: 98
Issue: E8
ISSN: 0148-0227
Subject Category
Lunar And Planetary Exploration
Accession Number
94A10141
Funding Number(s)
CONTRACT_GRANT: NAG9-240
Distribution Limits
Public
Copyright
Other

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