HR: 11:35h
AN: P21C-06    [PDF]
TI: Surface Properties of Mars' Northern High and Polar Latitudes, Including the Phoenix Landing Site
AU: * Vasavada, A R
EM: ashwin@ess.ucla.edu
AF: Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095
AU: Richardson, M I
EM: mir@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
AU: Christensen, P R
AF: Department of Geological Sciences, Arizona State University, Tempe, AZ 84287
AB: The unprecedented spatial resolution of the Mars Odyssey Thermal Emission Imaging System (THEMIS) is used to infer and compare the optical and thermal infrared properties of martian high-latitude and polar surfaces. Materials of interest include the north polar layered deposits (NPLD), the dark, dune-forming material associated with the north polar cap complex, and the ground ice-rich, latitude-dependent layer (the landing site of the Phoenix Scout mission). To address these goals, we have targeted and acquired THEMIS data as part of the Mars Odyssey Participating Scientist program. We use these THEMIS data in order to understand the morphology and color/thermal properties of the NPLD over relevant (i.e., m to km) spatial scales. We have assembled color mosaics of the data in order to map the distribution of ices, the different layered units, dark material, and underlying basement. The color information from THEMIS is crucial for distiguis-ing these different units, which are less distinct on Mars Orbiter Camera images. In the NPLD, we wish to understand the nature of the marginal scarps and their relationship to the dark material. Co-registered Mars Orbiter Laser Altimeter (MOLA) data provide a measure of scarp morphologies and may help identify the process(es) eroding the NPLD (e.g., mass wast-ing, wind, sublimation). The dark material (or perhaps a darker layered unit in planar configuration) is present at the feet of many scarps, but expresses dune bedforms only tens of kilometers away from the scarps. MOLA will help identify the relationship between the spatial distribution of dark material, the presence of bedforms, and the influence of topography. We have derived the thermophysical properties of the different materials using THEMIS and Mars Global Surveyor Thermal Emission Spectrometer (TES) data, also resulting in a new map of the thermal inertia of Mars' northern hemisphere. Such analyses are complicated by the need for atmospheric correction (of both radiatively active CO2 and dust) and accurate surface temperatures. In order to derive thermal inertias and thermally derived albedos, we employ a 1-D, radiative-convective thermal model of Mars surface, subsurface and atmosphere. The model uses simultaneous (or seasonally relevant) TES atmospheric dust opacities. We also are studying the effects of surface slopes on insolation using MOLA topographic data.
DE: 5462 Polar regions
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting