HR: 17:30h
AN: P24A-07    [Abstracts]
TI: Global Spectral and Compositional Diversity of Mars: A Test of CRISM Global Mapping with Mars Express OMEGA Data
AU: * Mustard, J F
EM: John\_Mustard@brown.edu
AF: Geological Sciences, Box 1846 Brown University, Providence, RI 02912 United States
AU: Bibring, J
AF: Institut d'Astrophysique Spatiale, Universite Paris-Sud, Orsay, 91405 France
AU: Pelkey, S
AF: Geological Sciences, Box 1846 Brown University, Providence, RI 02912 United States
AU: Milliken, R E
AF: Geological Sciences, Box 1846 Brown University, Providence, RI 02912 United States
AU: Langevin, Y
AF: Institut d'Astrophysique Spatiale, Universite Paris-Sud, Orsay, 91405 France
AU: Gondet, B
AF: Institut d'Astrophysique Spatiale, Universite Paris-Sud, Orsay, 91405 France
AU: Gendrin, A
AF: Institut d'Astrophysique Spatiale, Universite Paris-Sud, Orsay, 91405 France
AU: Poulet, F
AF: Institut d'Astrophysique Spatiale, Universite Paris-Sud, Orsay, 91405 France
AU: Erard, S
AF: Institut d'Astrophysique Spatiale, Universite Paris-Sud, Orsay, 91405 France
AU: Murchie, S L
AF: Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723 United States
AU: Arvidson, R E
AF: Earth and Planetary Sciences, Washington University, St. Louis, MO 63120 United States
AB: A new chapter in understanding the surface composition of Mars has begun with OMEGA, a visible-near infrared imaging spectrometer on the European Space Agency's Mars Express spacecraft. OMEGA acquires reflected solar spectra of Mars between 0.35 and 5.1 $\mu$m in 352 contiguous spectral channels. Thermal emission is also measured for wavelengths longer than $\sim$3.5 $\mu$m. Spatial resolution varies between 300 m and 4.8 km depending on pericenter altitude. Over its first 7 months of operation OMEGA has sampled all major geologic and geographic areas and is approaching complete coverage of the northern hemisphere of Mars. OMEGA data have increased our understanding of the types and distributions of the mafic minerals olivine and pyroxene, and have revealed large deposits of hydrated minerals, including sulfates and hydrated silicates. In August 2005, the CRISM spectrometer will be launched on NASA's Mars Reconnaissance Orbiter. CRISM covers a similar wavelength range to OMEGA, but will sample down to 18 m/pixel spatial resolution. CRISM will cover up to 5% of the surface at full spectral and spatial resolution, and 100% of the surface in 60 spectral bands and 200 m/pixel spatial resolution. In anticipation of CRISM data, we have been analyzing OMEGA data to test the CRISM strategy of evaluating information obtained by mapping spectral parameters, which are derived from the multispectral bands. OMEGA spectra are sampled to approximate CRISM multispectral band passes. For parameters requiring atmospheric correction, the data are only corrected for atmospheric transmission. A total of 36 parameters related to atmospheric and surface properties have been calculated from the multispectral bands using OMEGA data. Detailed analysis of these parameters reveals that much of the spectral diversity of Mars is captured using this multispectral approach. However, several of the parameters do not show relevant variations on Mars as anticipated, while variations observed at the full OMEGA spectral resolution are not captured by any of the current parameters. We are refining the choice of spectral parameters based on this work and will present global mapping of spectral parameters related to mafic minerals (pyroxene, olivine), sulfates, and hydrated minerals. The current suite of parameters highlight regional sulfate deposits in Terra Meridiani, Aram Chaos, and northwestern Arabia Terra, as well as numerous small-scale sulfate deposits in Valles Marineris. Mafic minerals are well discriminated by the parameters, showing pyroxene-rich volcanic rocks in expected regions such as Syrtis Major, but also revealing outcrops of pyroxene-rich bedrock in crater rims. Olivine-rich regions are observed in north-eastern Syrtis Major as well as on the floors of many craters in the southern hemisphere. These results demonstrate that the CRISM strategy for multispectral mapping will achieve its goals for a) global mapping of the spectral diversity of Mars, b) provide critical inputs for targeting high spectral and spatial resolution observations, and c) provide high value products for integrated global science investigations.
DE: 5410 Composition
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting