Asteroid surfaces: irradiation and VIS-NIR micro-spectroscopy in the laboratory - Rosario Brunetto (Site Buffon)

Rosario Brunetto - Institut d’Astrophysique Spatiale, Université Paris-Sud

Jeudi 30 mars 2017 à 14 h 30

IMPMC, Salle des élèves, 2ème étage, 61 rue Buffon, Paris 5ème (entrer par le 43 rue Buffon, plan Vigipirates oblige)

Abstract

Primitive extraterrestrial materials, such as meteorites and dust collected by sample return missions, are characterized by a large compositional heterogeneity at different scales. This heterogeneity has been observed in the laboratory by different techniques. Among these, micro-IR spectroscopy has the advantage of being totally non-destructive and allowing direct comparison with astronomical observations. With the development of Focal Plan Array detectors, IR mapping with high spatial resolution and IR tomography is now possible with a short acquisition time. In this presentation I will show some recent results of FTIR spectral imaging experiments on different extraterrestrial materials, obtained in collaboration with SMIS – Synchrotron SOLEIL (France).

In particular I will present new VIS-IR spectral imaging data of ion irradiated meteorites, simulating solar wind irradiation of asteroid surfaces. Together with direct evidence of weathering of asteroid Itokawa particles collected by Hayabusa, these results contribute to the spectral interpretation of asteroid observations, to establish an asteroids-meteorites link, and to understand the energetic processes affecting the surfaces of minor bodies. In laboratory-irradiated samples, we observe spectral modifications of the mineral and organic features, as well as variations in the albedo. These irradiation effects as a function of the irradiation dose are compared to the compositional heterogeneity of the pristine materials at micron-scale, to determine which spectral features are more sensitive to space weathering.

Results are discussed in the context of the next asteroid sample return missions Hayabusa 2 (JAXA) and OSIRIS-REx (NASA).