Earth Planets Space, Vol. 60 (No. 4), pp. 271-275, 2008
Tokuhiro Nimura1,2,3, Takahiro Hiroi1, and Carle M. Pieters1
1Department of Geological Sciences, Brown University, Providence, RI 02912, USA
2Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
3Department of Planetary Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan
(Received March 31, 2007; Revised November 6, 2007; Accepted November 25, 2007; Online published April 9, 2008)
In the remote detection of mineral compositions of planetary surface materials on airless bodies, space weathering is an obstacle which makes reflectance spectra redder and darker and weakens spectral features. This study attempts to model an effect of space weathering due to vapor coating by accounting for the change in surface reflectivity of regolith particles wherein nanophase-reduced iron (npFe0) particles are concentrated on their surfaces. When applied to a suite of reflectance spectra of lunar soils having different degrees of space weathering, this model can estimate the degrees of space weathering in terms of the thicknesses of the coating layer and provide an absorption coefficient spectrum of the host material.
Key words: Space weathering, airless bodies, vapor coating, surface reflectivity, regolith particles, modeling.