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Whole-disk spectrophotometric properties of Mercury: Synthesis of MESSENGER and ground-based observations |
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| Authors: | Deborah L. Domingue Faith Vilas Johan Warell Scott L. Murchie David T. Blewett Brian J. Anderson |
| Affiliation: | a Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA b MMT Observatory, P.O. Box 210065, University of Arizona, Tucson, AZ 85721, USA c Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA d Department of Physics and Astronomy, Division of Astronomy and Space Physics, Uppsala University, Box 515, SE-751 20 Uppsala, Sweden e School of Earth and Space Exploration, Arizona State University, Box 871404, Tempe, AZ 85287-1404, USA f Department of Astronomy, University of Maryland, College Park, MD 20742, USA |
| Abstract: | Disk-integrated and disk-resolved measurements of Mercury’s surface obtained by both the Mercury Dual Imaging System (MDIS) and the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) onboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft were analyzed and compared with previous ground-based observations of Mercury at 11 wavelengths. The spectra show no definitive absorption features and display a red spectral slope (increasing reflectance with increasing wavelength) typical of space-weathered rocky surfaces. The MDIS spectra show evidence of phase reddening, which is not observed in the MASCS spectra. The MDIS spectra are commensurate with ground-based observations to within 10%, whereas the MASCS spectra display greater discrepancies with ground-based observations at near-infrared wavelengths. The derived photometric calibrations provide corrections within 10% for observations taken at phase angles less than ∼100°. The derived photometric properties are indicative of a more compact regolith than that of the lunar surface or of average S-type asteroids. The photometric roughness of the surface is also much smoother than the Moon’s. The calculated geometric albedo (reflectance at zero phase) is higher than lunar values. The lower reflectance of immature units on Mercury compared with immature units on the Moon, in conjunction with the higher geometric albedo, is indicative of more complicated grain structures within Mercury’s regolith. |
| Keywords: | Photometry Mercury Spectra |
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