Mars History Derived from the Mineralogical Data of Omega/mex Acquired during the First Martian Year of Operation

Introduction: The pionneering Mariner and Viking optical mappings have revealed that Mars underwent an intense and active evolution, with tectonic, volcanic, water-driven and erosion processes that left record in a variety of surface structures. At the same time, they showed that Mars did not suffered a global surface reset, as it preserved areas dating from the early heavy bombardment. Major questions however remained unanswered, in particular with respect to the past climate: did Mars ever hosted Earth-like environmental conditions enabling liquid water to remain persistent? Is Mars a potential candidate for astrobiological search? The MGS/TES thermal infrared mapping has shown that Mars must have been cold and dry over most of its history (1). However, a few locations were identified as rich in grey hematite (2), suggesting they have been subjected to sustained aqueous processing. Here we present an updated view derived from the global mineralogical mapping acquired by the OMEGA instrument on board the Mars Express mission, during its first and nominal Martian year of operation.