Solar and Solar-Wind Composition Results from the Genesis Mission |
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Authors: | R C Wiens D S Burnett C M Hohenberg A Meshik V Heber A Grimberg R Wieler D B Reisenfeld |
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Institution: | (1) Los Alamos National Laboratory, MS D466, Los Alamos, NM, 87545, USA;(2) Geological & Planetary Sciences, MS 100-23, Caltech, Pasadena, CA 91125, USA;(3) Physics Department, Washington University, St. Louis, MO 63130, USA;(4) Isotope Geology NW C, ETH, 8092 Zurich, Switzerland;(5) Department of Physics & Astronomy, U. of Montana, MS 1080, 32 Campus Dr., Missoula, MT 59812, USA |
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Abstract: | The Genesis mission returned samples of solar wind to Earth in September 2004 for ground-based analyses of solar-wind composition,
particularly for isotope ratios. Substrates, consisting mostly of high-purity semiconductor materials, were exposed to the
solar wind at L1 from December 2001 to April 2004. In addition to a bulk sample of the solar wind, separate samples of coronal
hole (CH), interstream (IS), and coronal mass ejection material were obtained. Although many substrates were broken upon landing
due to the failure to deploy the parachute, a number of results have been obtained, and most of the primary science objectives
will likely be met. These objectives include He, Ne, Ar, Kr, and Xe isotope ratios in the bulk solar wind and in different
solar-wind regimes, and 15N/14N and 18O/17O/16O to high precision. The greatest successes to date have been with the noble gases. Light noble gases from bulk solar wind
and separate solar-wind regime samples have now been analyzed. Helium results show clear evidence of isotopic fractionation
between CH and IS samples, consistent with simplistic Coulomb drag theory predictions of fractionation between the photosphere
and different solar-wind regimes, though fractionation by wave heating is also a possible explanation. Neon results from closed
system stepped etching of bulk metallic glass have revealed the nature of isotopic fractionation as a function of depth, which
in lunar samples have for years deceptively suggested the presence of an additional, energetic component in solar wind trapped
in lunar grains and meteorites. Isotope ratios of the heavy noble gases, nitrogen, and oxygen are in the process of being
measured. |
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Keywords: | Composition: solar-wind Composition: solar Noble gases: solar |
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