In-situ propellant advantages for fast transfer to Mars

The advantages of in situ propellant for a fast transfer to Mars were studied as compared to all earth-based propellants and other options for reduction of total masss in low earth orbit. For a 10-year, 10-mission model and a baseline vehicle taken from the literature, the total reduction in number of earth launches was calculated. The scenario in which the return propellants are transferred to Mars on a slow cargo vehicle provides a 29-percent reduction in ALS launches over the baseline scenario in which all propellants are brought directly from earth. The scenarios in which in situ propellants are used for a successively greater portion of the total mission continue to reduce the number of launches required. With Mars propellant used for the Mars ascent vehicle and the return leg of the mission, a 59-percent reduction in launches is obtained. Finally, if the oxygen, or oxygen and fuel, for the outbound leg of the mission is also obtained by in situ production, from the moon for example, then the total reduction in number of earth launches is more than 80 percent.