Biosignature modification in the Oxia Planum region.

ESA's ExoMars 2020 Rosalind Franklin rover is expected to land on Mars in mid-2021, with a primary objective to search for signs of life. A landing site, Oxia Planum, has been selected that is rich in clay minerals, indicative of an environment that has been subjected to aqueous alteration in the past [1-3]. The prior presence of water may indicate that this region was once habitable, but any biosignatures (geochemical indicators for life) left behind may have been modified or even obliterated by subsequent surface processing, such as impact cratering, desiccation and diagenetic aqueous alteration