Visible and infrared spectroscopy of minerals and mixtures with the OMEGA/MARS-EXPRESS instrument

We present the reflectance measurements made with OMEGA during ground calibration on a selection of minerals and mixtures considered as candidates for constituents of the Mars surface. OMEGA is the visible and infrared mapping spectrometer designed to fly on-board the ESA/MARS-EXPRESS probe. These measurements allow to evaluate the instrument performances in identifying minerals as major or minor constituents (such as carbonates and sulfates). We use a new algorithm for the automatic detection of spectral features, and a multiple scattering model, to derive the mineralogical composition, the relative abundances and the mean grain size from the sample reflectance spectra. We discuss the implication on the OMEGA capability to meet its scientific objectives. In particular, the present work emphasize the interest of the 3–5 μm spectral range as a diagnostic one in the regions of Mars where the thermal emission will be low enough.