Application of a Rough-Surface Thermal Model to Observations of Mercury

A. Sprague, J. Emery, J. Bigelow (LPL, U of AZ), L. Deutsch (Boston University), J. Hora (IFA, U of HI), B. Hoffmann, A. Dayal (Steward Obs., U of AZ), F. Witteborn, D. Wooden (NASA ARC), J. Colwell (U of CO), R. Kozlowski, B. Ludwig (Susquehanna University)

Mid-infrared telescopic observations of Mercury show departures from models of rough-surface thermal emission that may be interpreted in terms of the emittance and reflectance of surface materials. The rough-surface thermal model of Emery et al. (LPSC Abs. XXVIII) has been removed from both 2-D images obtained at the Kitt Peak 90 inch observatory with MIRAC (Hoffmann et al. 1993 SPIE 1946) and from medium resolution spectra obtained from the Kuiper Airborne Observatory (KAO) (Sprague et al. LPSC Abs. XXVII) with HIFOGS (Witteborn et al. 1996, ASP Conf. Ser. 41). The residuals show features indicative of non-uniform emissivity in both spectral and spatial dimensions. These are interpreted in terms of non-uniformities in the composition and thermal conductivity of the surface.