Spectral Evidence for Hydrated Salts in Recurring Slope Lineae on Mars Authors: Lujendra Ojha1*, Mary Beth Wilhelm1, 2, Scott L. Murchie3, Alfred S. McEwen4, James J. Wray1, Jennifer Hanley5, Marion Massé6, Matt Chojnacki4, Affiliations: 1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA. 2Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, California, USA. 3Applied Physics Laboratory, Laurel, Maryland, USA. 4Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA. 5Department of Space Studies, Southwest Research Institute, Boulder, Colorado, USA. 6Laboratoire de Planétologie et Géodynamique, Nantes, France. This SOM contains (1) a general description of our dataset and methodology, (2) details of our atmospheric correction, validation approach and spectral mixture model, (3) supplementary figures to illustrate RSL activity and areas analyzed in CRISM images, and (4) Tables S1 and S2 that list the data used in this work. (1) Dataset and Methodology: CRISM1 full-resolution targeted (FRT ~18 m/pix), full-resolution short (FRS ~18 m/pix), and Along Track Oversampled (ATO 18 m/pix, with enhanced overlap to support processing to ~6 m/pixel) observations at Infrared (IR: 1.0-3.9 μm) wavelengths coordinated with HiRISE observations were used to examine the spectral characteristics of RSL. We chose not to inspect images in the VNIR detector range (0.4-1.0 μm), because our focus was clear evidence for or against signs of hydration, which is primarily detected using absorptions in the IR detector wavelength range. The CRISM images which were analyzed to study spectral characteristics of RSL described here are listed in Table S1, along with the coordinated HiRISE images in which the lineae were initially identified. Table S1 also lists the central latitude and longitude of the images along with their solar longitude (Ls), and exact coordinates for the location of spectra presented here. Table S2 lists exact coordinates of the denominator areas used to create the ratio spectra of RSL shown here. CRISM I/F images were downloaded from PDS and were preprocessed using ENVI’s (Exelis Visual Spectral evidence for hydrated salts in recurring slope lineae on Mars SUPPLEMENTARY INFORMATION DOI: 10.1038/NGEO2546