Proposed elements and an approach to evaluate the astrobiology potential of landing sites on Mars

The targeting of Mars surface missions aiming at astrobiology relevant analyses, requires a specific and also a complex evaluation of landing sites, besides the evaluation of engineering constraints. This chapter presents the evaluation of some aspects of the two remaining landing site candidates (Oxia Planum and Mawrth Vallis) for the ESA ExoMars 2020 rover, as examples to highlight the geological and astrobiological aspects in general. Past robotic missions to Mars mainly provided insight into the local geological context by analyzing outcrops on the surface or drilling down to a few cm-s below that. These lessons learned should be used in the future to increase the scientific outcome. Next missions will increase the research capacity, thus the need for improved targeted sampling will be necessary for their sophisticated instruments. Furthermore, new aspects might be involved in landing site selection including those that support to better understanding the geological context. The evaluation of the preservation potential of biosignatures at the landing site candidates will be also high priority in mission planning, using various instruments from orbiters, such as infrared, hyperspectral and optical datasets of different resolutions. Preservation potential could be very roughly estimated from thermal inertia, which is usually elevated for the less weathered rocks. However, it is difficult to take into account these astrobiology relevant parameters as deep craters or steep slopes provided outcrops are dangerous locations for robotic missions. This chapter evaluates these aspects using the parameters of the ExoMars 2020 rover, which mission will be able to study the “deeper” subsurface and its astrobiological potential in details by drilling, as well as geophysical and geochemical instruments