The Mars Project is a technical specification for a manned mission to Mars that von Braun wrote in 1948. The expected launch date was 1965. He envisioned an "enormous scientific expedition" involving a fleet of ten spacecraft with 70 crew members that would spend 443 days on the surface of Mars before returning to Earth. The spacecraft, seven passenger ships and three cargo ships, would be assembled in Earth orbit using materials supplied by reusable space shuttles. The fleet would use a nitric acid/hydrazinepropellant that, although corrosive and toxic, could be stored without refrigeration during the three-year round-trip to Mars. He calculated the size and weight of each ship, and how much fuel they would require for the round trip (5,320,000 metric tons). Hohmann trajectories would be used to move from Earth- to Mars-orbit, and von Braun computed each rocket burn necessary to effect the required manoeuvres.
Once in Mars orbit, the crew would use telescopes to find a suitable site for their base camp near the equator. A manned winged craft would detach itself from one of the orbiting ships and glide down to one of Mars' poles and use skis to land on the ice. The crew would then travel 6,500 km overland using crawlers to the identified base camp site and build a landing strip. The rest of the ground crew would descend from orbit to the landing strip in wheeled gliders. A skeleton crew would remain behind in the orbiting ships. The gliders would also serve as ascent craft to return the crew to the mother ships at the end of the ground mission.
Von Braun based his Mars Project on the large Antarctic expeditions of the day. For example, Operation Highjump (1946–1947) was a United States Navy program that included 4,700 men, 13 ships and 23 aircraft. At the time, Antarctic explorers were cut off from the rest of the world and the necessary skills had to be on hand to deal with any problem that arose. Von Braun expected the Martian explorers to face similar problems and included a large multi-disciplined crew in his mission, and multiple ships and landers for redundancy to reduce risk to personnel.
