Status: Study 1985. Gross mass: 325,000 kg (716,000 lb).
Produced at the urging of a Congressman in response to a perceived Soviet Mars expedition plan. The Soviet Union, and the space hardware planned by NASA, did not make it into the 1990's.
At the urging of ex-astronaut Harrison Schmitt, NASA and Los Alamos National Laboratory jointly hammered out a Mars Manned Mission at a seminar on 10-14 June 1985. The crash program was in response to the possibility that the Soviet Union might mount a manned Mars expedition as early as 1992 using its new Energia booster and experience with the Mir station. A year-long flyby mission would be launched, requiring a 350 metric ton spacecraft in low earth orbit. The spacecraft would have an 16.4 metric ton Mission Module, two expendable propellant tanks, a 5.5 metric ton command module, and use two NASA-planned Orbital Transfer Vehicles with a dry mass of 5.23 metric tons each. A total of 201 metric tons of liquid oxygen/liquid hydrogen propellant would be loaded into the OTV's and expendable tanks. A one hour OTV burn would place the spacecraft on its trajectory. The empty lateral propellant tanks would be retained in order to provide radiation and meteoroid protection for the crew. Six months after launch the spacecraft would zoom pass Mars, in a flyby phase lasting 150 minutes and beginning when the spacecraft was within 32,000 km of the planet. Closes approach to Mars would be 250 km. As the spacecraft approached earth, a single OTV and the Command Module would separate. Re-entry into the earth's atmosphere would come at 16.7 km/sec, a most difficult proposition as this was beyond OTV heat shield limits. It would also subject a crew that had been in zero-G for months to extremely high G forces. An alternative would be to use a fuelled OTV to brake the CM from 16.7 km/sec to 10.6 km/sec before the CM re-entered the earth's atmosphere. This was within the OTV's design limits but would double the initial mass required in low earth orbit. A Venus swing-by was not considered.