HR: 10:35h
AN: SH32A-02    [Abstracts]
TI: Solar Wind Helium, Neon and Argon Isotopic and Elemental Composition: Data from the Metallic Glass flown on NASA's Genesis Mission
AU: Grimberg, A
AF: Isotope Geochemistry and Mineral Resources ETH Zuerich, Clausiusstrasse 25, NW C, Zuerich, CH-8092, Switzerland
AU: * Bochsler, P
EM: Bochsler@soho.unibe.ch
AF: Physikalisches Institut University of Bern, Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Baur, H
AF: Isotope Geochemistry and Mineral Resources ETH Zuerich, Clausiusstrasse 25, NW C, Zuerich, CH-8092, Switzerland
AU: Buehler, F
AF: Physikalisches Institut University of Bern, Sidlerstrasse 5, Bern, CH-3012, Switzerland
AU: Wieler, R
AF: Isotope Geochemistry and Mineral Resources ETH Zuerich, Clausiusstrasse 25, NW C, Zuerich, CH-8092, Switzerland
AB: Solar wind helium, neon and argon trapped in a metallic glass target flown on NASA's Genesis mission were analyzed for their bulk composition and depth dependent distribution. The bulk isotopic and elemental composition for all elements is in good agreement with the mean values observed in the Apollo solar wind composition experiment. Adopting the measured solar wind velocity histogram during exposure, the isotopic composition of He, Ne, and Ar varies with depth within the metallic glass in a way generally consistent with ion- irradiation simulations of a solar wind of uniform composition. The similarity of the release patterns with the depth dependent distribution of trapped solar He, Ne, and Ar reported for lunar and asteroidal regolith samples shows that also the solar noble-gas record of extraterrestrial samples can be explained by mass separation of implanted solar wind with depth. This result confirms that contributions from high-energy particles to the solar wind fluence are minor, consistent with in-situ flux observations. On the other hand, a small gas fraction of the total solar gas in the metallic glass released from shallow depths is markedly enriched in the light isotopes relative to predictions from uniform isotopic implantation simulations. Contributions from interstellar gas or from the neutral solar wind are too small to explain this gas fraction. We tentatively attribute this superficially implanted gas to low-speed, current-sheet related solar wind, which was fractionated in the corona due to inefficient Coulomb drag, although the small apparent penetration depths associated to this component may be in conflict with this interpretation.
DE: 2151 Neutral particles (7837)
DE: 2152 Pickup ions
DE: 2164 Solar wind plasma
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Joint Assembly