https://phys.org/news/2018-05-red-planet-rover-extreme-environment.html

The ExoMars rover will be the first of its kind to drill below the surface – down to 2 m – and determine if evidence of life is buried underground, protected from the destructive radiation that impinges the surface today.

Like any space mission, the rover's mechanical structure, along with its electrical and thermal components and its interfaces with the scientific instruments, have to be tested to check they can survive their journey in space and operations at the destination.