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M. T. Mellon, B. M. Jakosky (University of Colorado), H. H. Kieffer (U.S. Geological Survey), P. R. Christensen (Arizona State University)
The thermal inertia of the martian surface layer has been derived from surface temperature data gathered by the Thermal Emission Spectrometer aboard Mars Global Surveyor during the early aerobraking phase of the mission. Diurnal oscillations in surface temperature are strongly dependent on the thermal and physical properties of the top several centimeters of the martian surface. Thermal inertia is a key property in defining these oscillations, combining conductivity, heat capacity, and density. Fine grained and loosely packed material typically exhibits a low value of thermal inertia, while higher values are common for rocks and exposed bedrock. Global mapping of thermal inertia provides insight into the physical character of the martian surface.
Deriving the thermal inertia from TES observations of surface temperature is accomplished by matching these observations with temperatures from a surface temperature model. In practice, a suite of correlated measurements (surface temperature, albedo, atmospheric dust opacity, etc.) are interpolated from a large set of pre-computed models to yield the thermal inertia that most closely mimics the observed temperature. Results indicate a global scale pattern of high and low thermal inertia values similar to that of Viking IRTM thermal inertia values. Smaller-scale differences are also apparent. These results will be presented.