The Martian Marine Corps is part of the MCR Armed Forces and the space naval infantry of the Martian Navy. The Mars Marine Corps is the counterpart of the UN Marine Corps, the marines serve on Martian-controlled outposts and navy ships throughout the system, including Ganymede before the incident. Like the UN Marines, they use powered, vacuum-rated armor in close-quarters combat and field a variety of firearms.
After shipping out aboard the MCRN Sirocco, Gunnery Sergeant Draper's unit was to land and secure Phoebe station. However Draper's unit never did secure it, the Scirocco fired torpedoes and destroyed the station to prevent the UN Marines from the UNNNathan Hale from landing on it.