The drone doesn't run on Linux either. It has several CPUs (like most spacecraft), most of them run hard realtime systems, and only the COTS board used for the

The drone doesn't run on Linux either. It has several CPUs (like most spacecraft), most of them run hard realtime systems, and only the COTS board used for the additional hazard avoidance (IIRC) runs Linux; it's not required for the helicopter to function. The whole point was to test non-radhard electronics on Mars without endangering the rover.