The MMX Rover: Performing in-situ Surface Investigations on Phobos

Abstract The Japanese MMX sample return mission to Phobos by JAXA will carry a Rover developed by CNES and DLR that will be deployed on Phobos to perform in-situ analysis of the Martian moon's surface properties. Past images of the surface of Phobos show that it is covered by a layer of regolith. However, the mechanical and compositional properties of this regolith are poorly constrained. In particular nothing is known regarding the particle sizes, their chemical composition, the packing density of the regolith as well as other frictional parameters and surface dynamics from current remote images. Understanding the properties and dynamics of the regolith in the low-gravity environment of Phobos is important to trace back its history and surface evolution. Moreover, this information is also important to support the interpretation of data obtained by instruments onboard the main spacecraft and to minimize the risks involved in the sampling by the spacecraft. The instruments onboard the Rover are an infrared radiometer (miniRad), a Raman spectrometer (RAX), two cameras looking forwards for navigation and science purposes (NavCams), and two cameras observing the flow of regolith around the rover wheels (WheelCams). The Rover will be deployed before the sampling of Phobos' surface by MMX spacecraft and will be the first rover driving on a Martian moon and in a low-gravity environment.