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Mass fractionation of the lunar surface by solar wind sputtering

Switkowski, Z. E. and Haff, P. K. and Tombrello, T. A. and Burnett, D. S. (1977) Mass fractionation of the lunar surface by solar wind sputtering. Journal of Geophysical Research, 82 (26). pp. 3797-3804. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20141105-155414599

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Abstract

The sputtering of the lunar surface by the solar wind is examined as a possible mechanism of mass fractionation. Simple arguments based on current theories of sputtering and the ballistics of the sputtered atoms suggest that most ejected atoms will have sufficiently high energy to escape lunar gravity. However, the fraction of atoms which falls back to the surface is enriched in the heavier atomic components in relation to the lighter ones. This material is incorporated into the heavily radiation-damaged outer surfaces of grains, where it is subject to resputtering. Calculations predict that an equilibrium surface layer, enriched in heavier atoms, will form with δ(^(18)O) ≈ +20‰ ≈ δ(^(30)Si) and that oxygen will be depleted on the surface layers of grains relative to the bulk composition by about 12.5%. These results are in fair agreement with experiment. The dependence of the calculated results upon the energy spectrum of sputtered particles is investigated. We conclude that mass fractionation by solar wind sputtering is likely to be an important phenomenon on the lunar surface but that the complex isotopic variations observed in lunar soils cannot be completely explained by this mechanism.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/JB082i026p03797DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/JB082i026p03797/abstractPublisherArticle
Additional Information:Copyright 1977 by the American Geophysical Union. (Received September 13, 1976; revised May 5, 1977; accepted May 5, 1977.) Paper number 7B0384. This work was supported in part by the National Science Foundation (PHY76-83685) and the National Aeronautics and Space Administration (NGR 05-002-333).
Funders:
Funding AgencyGrant Number
NSFPHY76-83685
NASANGR 05-002-333
Record Number:CaltechAUTHORS:20141105-155414599
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141105-155414599
Official Citation:Switkowski, Z. E., P. K. Haff, T. A. Tombrello, and D. S. Burnett (1977), Mass fractionation of the lunar surface by solar wind sputtering, J. Geophys. Res., 82(26), 3797–3804, doi:10.1029/JB082i026p03797.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51343
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:06 Nov 2014 17:55
Last Modified:13 Feb 2019 18:06

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