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R. N. Clark, T. M. Hoefen (USGS), R. Pearson (USBR), N. Gorelick, P. R. Christensen (ASU), TES Science Team
The Mars Global Surveyor (MGS) aerobraking orbit provided a unique opportunity to obtain near global coverage of Mars with the Thermal Emission Spectrometer (TES) in all spectral channels. The TES covers the 6.25 to 50 micron spectral range with 143 spectral channels, obtaining 6 spectra every 2 seconds. The elliptical orbit provided for varied ground spatial resolutions. We assembled multiple orbit TES data into 1440x720x143 imaging spectroscopy cubes at 0.25 pixel per degree spatial sampling (15 km/image pixel), using the best available data.
The first data set consists of night-side data covering about 30 S to 60 N latitude with about 80 pixel sizes 60-80 km, and lower spatial resolution to the north pole. Temperatures ranged from 165 to 210 Kelvin, averaging ~185K. MGS orbits 14-35 at TES icks 61000-64000 were used. (TES icks are TES time intervals = 2 seconds/ick.)
A low resolution data set on the day side covers from 20 S to 65 S at about 20 45 by 90 km from orbits 1-35 and 70-120 (orbits 36-69 were excluded because of a dust storm), using TES icks 1350-2850. Temperatures for ranged from 210 to 270 Kelvin, averaging ~240 K.
The image cubes were calibrated to radiance, relative emissivity derived, and processed to map for potential mineral features, both in emission and absorption. While the major silicate feature near 9-10 microns maps everywhere (dominated by dust), other potential mineral features are considerably weaker. The mapping shows that there are no large scale expanses of minerals such as carbonates at this spatial resolution, but does not preclude their existence in smaller scale outcrops. No additional extensive exposures of large grained hematite similar to that already found by TES are seen elsewhere on the planet, at least at this low spatial resolution. Mineral maps and potential surface features will be presented at the meeting.
The author(s) of this abstract have provided an email address for comments about the abstract: rclark@speclab.cr.usgs.gov