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PI : Henner Busemann

Title : The characterisation of the asteroid Itokawa regolith - A correlated study by X-ray tomography, micro-Raman spectroscopy and high-sensitivity noble gas analysis

Abstract

The initial analyses of asteroid Itokawa samples returned with JAXA’s Hayabusa mission revealed a wealth of important results concerning parent body history, regolithic environment, petrology, mineralogy, geochemistry and light noble gases (Science, 2011, Vol. 333, 1113-1131). However, some important studies could not be accomplished yet. Here we suggest studying 10 Itokawa grains by a large consortium. We aim to determine the noble gas abundances including Kr and Xe, and mineralogy and morphology of these grains. We wish to better understand processes in the regolith of Itokawa, solar wind incorporation and exposure to cosmic rays and the erosion rate of the regolith. Furthermore, we plan to analyse the halogen and possibly detectable trapped Kr and Xe abundances, and try to improve our knowledge of the chronology of Itokawa. We will apply non-destructive Raman spectroscopy and synchrotron X-ray tomography and, ultimately, laser extraction and noble gas mass spectrometry. The expected concentrations of Kr and Xe are extremely low. Hence, we have to request relatively large samples and suggest to analyse them with the worldwide-unique high-sensitivity resonance ionisation time-of-flight mass spectrometers RIMSKI and RELAX in Manchester. Similarly, we will apply the unique high-sensitivity compressor source at ETH Zurich on small fragments of the same grains, in order to improve the data base for He-Ar and discuss a complete noble gas data set for each grain. To reduce terrestrial contamination affecting mostly Kr and Xe, we request and try to process all grains entirely in a N2 atmosphere.

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