Characterizing irradiated surfaces using IR spectroscopy

Solar wind ion irradiation continuously modifies the optical properties of unprotected surfaces in the Solar System. This alteration induces significant biases in the interpretation of the sub-surface pristine bulk composition through remote sensing. However, as the alteration of the surface is a function of time, an in-depth understanding of the phenomenon may provide an original way to estimate the weathering age of a surface. Here we show new IR data of ion irradiated carbonaceous chondrite meteorites. Our laboratory experiments show that mid- and far-IR bands of irradiated meteorites are very sensitive to space weathering, as they are significantly modified upon irradiation. These bands can thus constitute a reliable proxy of the time-bound effects of irradiation on airless bodies. We show that the detection of irradiation effects is within the reach of IR spectral resolution of the OSIRIS-REx mission and of the future James Webb Space Telescope.