Possible geomorphic indicators of methane emission in three Martian impact craters

Methane has been detected these last years in the Martian atmosphere both from orbit (TGO-ExoMars mission - still active) and from ground (Curiosity rover – Mars Science laboratory mission). The sources of methane remain undetected. As the life time of methane in the Martian atmosphere should be less than few months, these sources are currently active at the Martian surface. The localization and the geometry of these sources remain an open question. Emission centers could be localized in peculiar zones on which it is possible to detect methane. Methane could also be emitted in wide areas and be locally concentrated by atmospheric processes. The aim of this study is to compare the geology and geomorphology three impact craters (Gale, Gusev and Vernal) in which methane has been detected from orbit and/or from ground. Satellite and in situ hyperspectral data (for Gusev, hyperspectral data from Spirit - for Gale, data from Curiosity), as well as high-resolution Context Camera (CTX) and HiRISE images (MRO mission) were also considered. Digital Elevation Models (DEM) were calculated from the highest resolution images that are available. Geomorphological maps were drawn for each crater through GIS projects. For each crater, the possible areas of emission are defined from criteria defined on terrestrial analogs located in Chile and Antarctica. Differences and similarities between the three selected craters are discussed.