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...

No abstract

No abstract

Thermal infrared spectral measurements will be made of the surface and atmosphere of Mars by the thermal emission spectrometer (TES) on board Mars Observer. By using these observations the composition of the surface rocks, minerals, and condensates will be determined and mapped. In addition, the composition and distribution of atmospheric dust and condensate clouds, together with temperature profiles of the CO2 atmosphere, will be determined. Broadband solar reflectance and thermal emittance measurements will also be made to determine the energy balance in the polar regions and to map the thermophysical properties of the surface. The specific science objectives of this investigation are to determine (1) the composition and distribution of surface materials, (2) the composition, particle size, and spatial and temporal distribution of suspended dust, (3) the location, temperature, height, and water abundance of H2O clouds, (4) the composition, seasonal behavior, total energy balance, and physical properties of the polar caps, and (5) the particle size distribution of rocks and fines on the surface. The instrument consists of three subsections: a Michelson interferometer, a solar reflectance sensor, and a broadband radiance sensor. The spectrometer covers the wavelength range from 6 to 50 μm (∼1600–200 cm−1) with nominal 5 and 10 cm−1 spectral resolution. The solar reflectance band extends from 0.3 to 2.7 μm; the broadband radiance channel extends from 5.5 to 100 μm. There are six 8.3‐mrad fields of view for each sensor arranged in a 3 × 2 array, each with 3‐km resolution at the nadir. Uncooled deuterated triglycine sulphate (DTGS) pyroelectic detectors provide a signal‐to‐noise ratio (SNR) of over 500 at 10 μm for daytime spectral observations at a surface temperature of 270 K. The SNR of the albedo and thermal bolometers will be approximately 2000 at the peak signal levels expected. The instrument is 23.6 × 35.5 × 40.0 cm, with a mass of 14.4 kg and an average power consumption of 14.5 W. The approach will be to measure the spectral properties of thermal energy emitted from the surface and atmosphere. Emission phase angle studies and day‐night observations will be used to separate the spectral character of the surface and atmosphere. The distinctive thermal infrared spectral features present in minerals, rocks, and condensates will be used to determine the mineralogic and petrologic character of the surface and to identify and study aerosols and volatiles in the atmosphere.

[1] The Miniature Thermal Emission Spectrometer (Mini-TES) will provide remote measurements of mineralogy and thermophysical properties of the scene surrounding the Mars Exploration Rovers and guide the rovers to key targets for detailed in situ measurements by other rover experiments. The specific scientific objectives of the Mini-TES investigation are to (1) determine the mineralogy of rocks and soils, (2) determine the thermophysical properties of selected soil patches, and (3) determine the temperature profile, dust and water-ice opacity, and water vapor abundance in the lower atmospheric boundary layer. The Mini-TES is a Fourier Transform Spectrometer covering the spectral range 5-29 mm (339.50 to 1997.06 cm À1 ) with a spectral sample interval of 9.99 cm À1 . The Mini-TES telescope is a 6.35-cm-diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a voice-coil motor assembly. A single deuterated triglycine sulfate (DTGS) uncooled pyroelectric detector with proven space heritage gives a spatial resolution of 20 mrad; an actuated field stop can reduce the field of view to 8 mrad. Mini-TES is mounted within the rover's Warm Electronics Box and views the terrain using its internal telescope looking up the hollow shaft of the Pancam Mast Assembly (PMA) to the fixed fold mirror and rotating elevation scan mirror in the PMA head located $1.5 m above the ground. The PMA provides a full 360°of azimuth travel and views from 30°above the nominal horizon to 50°below. An interferogram is collected every two seconds and transmitted to the Rover computer, where the Fast Fourier Transform, spectral summing, lossless compression, and data formatting are performed prior to transmission to Earth. Radiometric calibration is provided by two calibration V-groove blackbody targets instrumented with platinum thermistor temperature sensors with absolute temperature calibration of ±0.1°C. One calibration target is located inside the PMA head; the second is on the Rover deck. The Mini-TES temperature is expected to vary diurnally from À10 to +30°C, with most surface composition data collected at scene temperatures >270 K. For these conditions the radiometric precision for two-spectra summing is ±1.8 Â 10 À8 W cm À2 sr À1 /cm À1 between 450 and 1500 cm À1 , increasing to $4.2 Â 10 À8 W cm À2 sr À1 /cm À1 at shorter (300 cm À1 ) and longer (1800 cm À1 ) wave numbers. The absolute radiance error will be <5 Â 10 À8 W cm À2 sr À1 /cm À1 , decreasing to $1 Â 10 À8 W cm À2 sr À1 /cm À1 over the wave number range where the scene temperature will be determined (1200-1600 cm À1 ). The worst-case sum of these random and systematic radiance errors corresponds to an absolute temperature error of $0.4 K for a true surface temperature of 270 K and $1.5 K for a surface at 180 K. The Mini-TES will be operated in a 20-mrad panorama mode and an 8-mrad targeted mode, producing two-JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. E12, 8064, doi:10.1029/2003JE002117, 2003