Oxia Planum is a plain located on Mars (near 18.2°N 336°E) that has been chosen as a preferred landing location for the ExoMars rover. Oxia Planum contains one of the largest exposures of rocks that are around 3.9 billion years old. The site is clay-rich, indicating that water once played a role here. The site sits in an area of valley systems with the exposed rocks exhibiting different compositions, indicating a variety of deposition and wetting environments. Clay may offer preservation for biosignatures against the planet's harsh radiation and oxidation environment