The Angry Red Planet (1959)

The first spaceship to Mars, presumed lost, is found in space and brought back to Earth by remote control. Only two from an initial crew of four are still alive, but one is unconscious due to an attached alien growth, while the other is traumatized, blocking out all memory of what happened. In hopes to save the unconscious crewman, the amnesiac is interrogated back into remembering. Those in charge thereby learn of the terrible dangers awaiting anyone venturing into the spooky, ruddy stillness of the very alien Martian ecosystem.