DUST OFF. The Thermal Emission Spectrometer (TES) spotted regions of Mars that had relatively warm overnight temperatures, suggesting they were wholly or largely free of blanketing dust. This image shows where TES saw rockier areas (reddish tones) and dustier ones (purple). Click on the image to download a larger version (2.8 MB). NASA/JPL/Arizona State University
References:
Christensen, P.R., J.L. Bandfield, J.F. Bell, III, N. Gorelick, V.E. Hamilton, A. Ivanov, B.M. Jakosky, H.H. Kieffer, M.D. Lane, M.C. Malin, G.L. Mehall, T. McConnochie, A.S. McEwen, H.Y. McSween, Jr., J.E. Moersch, K.H. Nealson, J.W. Rice, Jr., M.I. Richardson, S.W. Ruff, M.D. Smith, T.N.Titus, and W. Wyatt, Morphology and composition of the surface of Mars: Mars Odyssey THEMIS results, Science, 300, 2056-2061, 2003.
Rogers, A.D., P.R.Christensen, and J.L. Bandfield, Compositional heterogeneity of the ancient martian crust: Analysis of Ares Vallis bedrock with THEMIS and TES data, J. Geophys. Res., 110, E05010, doi:10.1029/2005JE002399, 2005.