Mars Mission profile options and mission requirements data are presented for Earth-Mars opposition and conjunction class round-trip flyby and stopover mission opportunities. The opposition class flyby and sprint mission uses direct transfer trajectories to and on return from Mars. The opposition class stopover mission employs the gravitational field of Venus to accelerate the space vehicle on either the outbound or inbound leg in order to reduce the propulsion requirement associated with the opposition class mission. The conjunction class, mission minimizes propulsion requirements by optimizing the stopover time at Mars. Representative interplanetary space vehicle systems are sized to compare and show sensitivity of the initial mass required in low Earth orbit to one mission profile option and mission opportunity to another
