Application of TES Spectral Data to Rock Varnish Taylor Feiereisel Mentors: Shawn Wright Laurie Rogers

Overview: Orbital TES thermal infrared (TIR) spectral data concludes two different types of rock surfaces on Mars in the low albedo regions of Mars Surface Type I (STI) = Basalt Surface Type II (STII) = ??? Clay-manganiferous rock coatings called desert varnish could manipulate the TES TIR STII spectral data. Approach: Laboratory Spectroscopy Results and Implications Acknowledgements

Mars TIR History: Mars Global Surveyor Mars Odyssey 2001 THEMIS TES

STI and STII Sites Northern Hemisphere Southern Hemisphere Sources: Wyatt and McSween, 2002; Hamilton et al., 2003 Southern Hemisphere

Rock Coatings: Rock Coatings are additional sub aerial layers on a rock derived through multiple biochemical and geomorphologic processes. Desert Varnishes are dark rock coatings that are composed of clay minerals cemented to the underlying rock by oxides of Mn, Fe, or both. Weathering a rock will breakdown and decay the lithosphere into products that are in equilibrium with conditions at or near the earth’s (rock’s) surface. Weathering processes also forms new compounds. Dorn, Rock Coatings, 1998

Approach: Collected rock samples from around the world in arid climates. Multiple spectral readings of fresh and desert varnished sides SW U.S., India, Argentina Obtained TIR emission spectroscopy Compare terrestrial samples to TES STII spectral readings.

Results: Fresh Surfaces were primarily basalt and obsidian Desert Varnishes were the same on various fresh surfaces

Results: The main component of desert varnish is likely the clay Montmorillonite

Results: Varnishes vary considerably within the individual rocks and within the same varnish.

Conclusions: Desert varnishes uses the surrounding environment for material to create the layer Surface Type II rocks on Mars are not completely varnished by clay materials

Acknowledgements RATW and MSFF NASA Space Grant