A Consortium status report: the characterisation of the asteroid Itokawa regolith - a correlated study by X-ray tomography, micro-raman spectroscopy, and high-sensitivity noble gas analysis

Abstract

Precious samples from S-type as-teroid 25143 Itokawa have been sampled by the JAXA (Japanese Space Agency) Hayabusa mission in 2005 and returned to Earth in 2010. Itokawa is, succeeding the Moon and comet Wild 2, the third planetary body successfully probed by a sample return mission. The initial studies revealed that Itokawa consists mostly of type LL5-6 material. It experienced severe surface alteration due to space weathering, as docu-mented by surficial, nanosize S-and Fe-bearing phases in some grains. Noble gas studies indicate that Itokawa experiences a surprisingly intense surface loss at a rate of tens of cm/Ma, implying that Itokawa (largest dimension ~540 m) will be destroyed quickly. We received material through JAXA in Sept. 2012 and aim to analyze noble gases in Itokawa samples with high sensitivity, including Kr and Xe, which could not be studied previously, because of the low concentrations. We will combine the noble gas studies with scanning microRaman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and synchro-tron radiation X-ray tomographic microscopy (SRXTM). These provide non-destructive characteri-zations of grain density, mineralogy, structure, and potential space weathering, which are essential to as-sess gas concentrations of potentially present cosmogenic, solar, trapped and radiogenic compo-nents. Here, we summarize the work of our consortium performed so far. Further studies will be presented at the meeting.