- Conference date: 6-9 March 2001
- Location: Bern (Switzerland)
Solar wind implanted in surface layers (≲0.03 μm) of lunar soil grains has often been analyzed to infer the history of the solar wind. In somewhat deeper layers, and thus presumably at higher implantation energies, a mysterious population, dubbed “SEP” for “solar energetic particle,” accounts for the majority of the implanted gas-several orders of magnitude more than expected from the present-day flux of solar energetic particles. In addition, its elemental and isotopic composition is distinct from that of the solar system. While the heavy Ne isotopes are enriched relative to is depleted relative to -a behavior that is hard to explain with acceleration of solar material. N is overabundant with respect to the noble gases (especially Ar). Here we show that interstellar pick-up ions (PUIs) which are ionized and accelerated in the heliosphere and subsequently implanted in lunar regolith grains can account for the properties of the “SEP” population. This implies that lunar soils preserve samples of the galactic environment of the solar system and may eventually be used as an archive for solar system “climate”.
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