It is able to image different ground densities, structural layers, buried rocks, meteorites, and detect underground water ice and salty brine at 10 m (33 ft) depth.

Ground-penetrating radars (GPR) send radio frequency electromagnetic waves into the ground and then detect the reflected signals as a function of time to reveal subsurface structure as well as composition.

[4] The RIMFAX instrument was developed and built by FFI, and it was delivered to NASA's Jet Propulsion Laboratory for integration with the rover in December 2018.

[6] The RIMFAX principal investigator is Svein-Erik Hamran of FFI, and his team includes scientists from Norway, Canada and the United States.

RIMFAX is commanded to acquire radar soundings every 10–20 cm along the rover's path to create two-dimensional GPR images of subsurface structure.