How shall we go to Mars? A review of mission scenarios

Four scenarios for initial Mars missions are examined in this overview of strategies. The scenarios are compared to determine the most effective option with respect to the effects of reduced gravity, exposure to space radiation, and cost. Mission cost is evaluated based on initial mass in earth orbit for the four mission types: classes-opposition, conjunction, fast-transfer conjunction, and split sprint. The reduced gravitational force on the Martian surface is considered to be a critical factor because the physical deconditioning at 3/8 earth gravity is assumed to approximate that of zero gravity. Exposure to radiation is not determined to be a definite discriminator because none of the scenarios exceed established limits. The split sprint is championed based on the high energy transfers considered and with chemical propulsion (or preferably nuclear thermal propulsion) and aerobraking.