Thermal Emission Spectrometer (TES) data from the Mars Global Surveyor (MCS) are used t o determine compositions and distributions of martian lowalbedo regions. Two surface spectral signatures are identified from low-albedo regions. Comparisons with spectra of terrestrial rock samples and deconvolution results indicate that the t w o compositions are a basaltic composition dominated by plagioclase feldspar and clinopyroxene and an andesitic composition dominated by plagioclase feldspar and volcanic glass. The distribution of the t w o compositions is split roughly along the planetary dichotomy. The basaltic composition is confined t o older surfaces, and the more silicic composition is concentrated in the younger northern plains.A major objective of the TES investigation is to determine and map the mineralogy of the martian surface in order to understand the formation and development of Mars. To understand present and past conditions on Mars, it is important to determine if the surface materials are, for example, volcanic, weathering products, or chemical precipitates. We demonstrate here that martian dark materials are volcanic and that they vary significantly across the planet. These findings can help lead to an understanding of planetary mechanisms such as the development of the martian crust, heat loss processes, bulk composition, magma differentiation, and source materials of the martian soil and dust.Previous studies have developed the methodology for separating the surface and atmospheric components of the emission of Mars

Abstract. The Thermal Emission Spectrometer (TES) investigation on Mars GlobalThe TES data are calibrated to a 1-o-precision of 2.5 -6 X 10 -8 W cm -2 sr-1/cm -•, 1.6 x 10 -6 W cm -2 sr -•, and -0.5 K in the spectrometer, visible/near-IR bolometer, and IR bolometer, respectively_. These instrument subsections are calibrated to an absolute accuracy of-4 x 10 -8 W cm -2 sr-•/cm -• (0.5 K at 280 K), 1-2%, and -1-2 K, respectively. Global mapping of surface mineralogy at a spatial resolution of 3 km has shown the following: (1) The mineralogic composition of dark regions varies from basaltic, primarily plagioclase feldspar and clinopyroxene, in the ancient, southern highlands to andesitic, dominated by plagioclase feldspar and volcanic glass, in the younger northern plains. (2) Aqueous mineralization has produced gray, crystalline hematite in limited regions under ambient or hydrothermal conditions; these deposits are interpreted to be in-place sedimentary rock formations and indicate that liquid water was stable near the surface for a long period of time. (3) There is no evidence for large-scale (tens of kilometers) occurrences of moderate-grained (>50-•m) carbonates exposed at the surface at a detection limit of -10%. (4) Unweathered volcanic minerals dominate the spectral properties of dark regions, and weathering products, such as clays, have not been observed anywhere above a detection limit of -10%; this lack of evidence for chemical weathering indicates a geologic history dominated by a cold, dry climate in which mechanical, rather than chemical, weathering was the significant form of erosion and sediment production. (5) There is no conclusive evidence for sulfate minerals at a detection limit of -15%. The polar region has been studied with the following major conclusions: (1) Condensed CO2 has three distinct end-members, from fine-grained crystals to slab ice. (2) The growth and retreat of the polar caps observed by MGS is virtually the same as observed by Viking 12 Martian years ago. (3) Unique regions have been identified that appear to differ primarily in the grain size of CO2; one south polar region appears to remain as black slab CO2 ice throughout its sublimation. (4) Regional atmospheric dust is common in localized and regional dust storms around the margin and interior of the southern cap. Analysis of the thermophysical properties of the surface shows that (1) the spatial pattern of albedo has changed since Viking observations, (2) a unique cluster of surface materials with intermediate inertia and albedo occurs that is distinct from the previously identified lowinertia/bright and high-inertia/dark surfaces, and (3) localized patches of high-inertia material have been found in topographic lows and may have been formed by a unique set of aeolian, fluvial, or erosional processes or may be exposed bedrock.• •Raytheon Santa Barbara Remote Sensing, Goleta, California. IntroductionThe Thermal Emission Spectrometer (TES) experiment is designed to address a wide range of science objectives, including the de...

[ 1 ] Determining the mineralogy of Mars is an essential part of revealing the conditions of the surface and subsurface. A deconvolution method was used to remove atmospheric components and determine surface mineralogy from Thermal Emission Spectrometer data at 1 pixel per degree (ppd). Minerals are grouped into categories on the basis of compositional and spectral similarity, and global concentration maps are produced. All binned pixels are fit well with RMS errors of 0.005 in emissivity. Higher RMS errors are attributed to short wavelength particle size effects on dust-covered surfaces. Significant concentrations (>0.10) of plagioclase, high-Ca pyroxene, sheet silicates/high-Si glass, and hematite are detected and display distributions consistent with previous studies. Elevated concentrations of plagioclase and high-Ca pyroxene are consistent with basaltic surfaces and are located in low-albedo highlands regions north of $ 45° S. Significant concentrations of plagioclase and sheet silicates/high-Si glass and low concentrations of high-Ca pyroxenes are consistent with andesitic surfaces and are concentrated in both southern and northern high-latitude, low-albedo regions. Andesitic surfaces in the southern hemisphere have a lower spectral contrast than northern surfaces. An isolated surface located in Solis Planum is spectrally distinct but compositionally similar to other surfaces interpreted to be andesitic in composition. Concentrations of olivine below the detection limit correctly identify its presence in two of three locations. Potassium feldspar, low-Ca pyroxene, basaltic glass, olivine, sulfate, carbonate, quartz, and amphibole are not detected with confidence at 1 ppd. The results presented here indicate a predominance of volcanic compositions within Martian dust-free surfaces.

We used infrared data from the Lunar Reconnaissance Orbiter (LRO) Diviner Lunar Radiometer Experiment to globally map thermophysical properties of the Moon's regolith fines layer. Thermal conductivity varies from 7.4 × 10−4 W m−1 K−1 at the surface to 3.4 × 10−3 W m−1 K−1 at depths of ~1 m, given density values of 1,100 kg m−3 at the surface to 1,800 kg m−3 at 1 m depth. On average, the scale height of these profiles is ~7 cm, corresponding to a thermal inertia of 55 ± 2 J m−2 K−1 s−1/2 at 273 K, relevant to the diurnally active near‐surface layer, ~4–7 cm. The temperature dependence of thermal conductivity and heat capacity leads to an ~2 times diurnal variation in thermal inertia at the equator. On global scales, the regolith fines are remarkably uniform, implying rapid homogenization by impact gardening of this layer on timescales <1 Gyr. Regional‐ and local‐scale variations show prominent impact features <1 Gyr old, including higher thermal inertia (> 100 J m−2 K−1 s−1/2) in the interiors and ejecta of Copernican‐aged impact craters and lower thermal inertia (< 50 J m−2 K−1 s−1/2) within the lunar cold spots identified by Bandfield et al. (2014). Observed trends in ejecta thermal inertia provide a potential tool for age dating craters of previously unknown age, complementary to the approach suggested by Ghent et al. (2014). Several anomalous regions are identified in the global 128 pixels per degree maps presented here, including a high‐thermal inertia deposit near the antipode of Tycho crater.

Chlorides commonly precipitate during the evaporation of surface water or groundwater and during volcanic outgassing. Spectrally distinct surface deposits consistent with chloride-bearing materials have been identified and mapped using data from the 2001 Mars Odyssey Thermal Emission Imaging System. These deposits are found throughout regions of low albedo in the southern highlands of Mars. Geomorphologic evidence from orbiting imagery reveals these deposits to be light-toned relative to their surroundings and to be polygonally fractured. The deposits are small (< ∼25 km 2 ) but globally widespread, occurring in middle to late Noachian terrains with a few occurrences in early Hesperian terrains. The identification of chlorides in the ancient southern highlands suggests that near-surface water was available and widespread in early Martian history.