Dust coatings on basaltic rocks and implications for thermal infrared spectroscopy of Mars

摘要: [1] Thin coatings of atmospherically deposited dust can mask the spectral characteristics underlying surfaces on Mars from visible to thermal infrared wavelengths, making identification substrate and coating mineralogy difficult lander orbiter spectrometer data. To study effects coatings, we acquired emission hemispherical reflectance spectra (5–25 μm; 2000–400 cm−1) basaltic andesite coated with different thicknesses air fall-deposited palagonitic soils, fine-grained ceramic clay powders, terrestrial loess. The results show that thin (10–20 μm) reduce contrast rock substantially, consistent previous work. This reduction continues linearly increasing thickness until a “saturation thickness” is reached, after which little further change observed. saturation spectrally flat palagonite ∼100–120 μm, whereas for higher only ∼50–75 μm. Spectral differences among uncoated samples correlate measured in quadratic manner, correlations estimated surface area coverage are better fit by linear functions. Linear mixture modeling using materials as end-members also their areal coverage. A comparison ratios Thermal Emission Spectrometer (TES) dark bright intracrater windstreak deposits associated Radau crater suggests material may be much 90% dust. data presented here will help improve interpretations upcoming mini-TES Imaging System (THEMIS) observations materials.