Oxia Planum is one of four candidate landing sites under consideration for the ExoMars 2018 mission. It contains one of the largest exposures of ancient – approximately 3.8 billion years old – clay-rich rocks on the planet. The finely layered formations record a variety of deposition and wetting environments believed to be similar to that of Mawrth Vallis.
The image combines HRSC images from ESA Mars Express with MOLA topography data from NASA's Mars Global Surveyor. The landing ellipses under evaluation for site selection are indicated, and cover an area of 104 × 19 km. The orientation of the landing ellipse depends on when the launch takes place within a given launch window – the sites have to be compliant with launch opportunities in both 2018 and 2020, as indicated.