THERMAL EMISSION MEASUREMENTS 2000-400 CM-1 (5-25 MU-M) OF HAWAIIAN PALAGONITIC SOILS AND THEIR IMPLICATIONS FOR MARS

The thermal emission of two palagonitic soils, common visible and near infrared spectral analogs for bright soils on Mars, was measured over the wavelength range of 5 to 25 mu m (2000 to 400 cm(-1)) for several particle size separates. All spectra exhibit emissivity features due to vibrations associated with H2O and SiO. The maximum variability of emissivity is approximate to 20% in the short wavelength region (5 to 6.5 mu m, 2000 to 1500 cm(-1)), and is more subdued, <4%, at longer wa velengths. The strengths of features present in infrared spectra of Ma rs cannot be solely provided by emissivity variations of palagonite; s ome other material or mechanism must provide additional absorption(s).