> Mission Overview > Mars Direct Plan I. The earth Return Vehicle (ERV) is launched from Earth atop a Magnum booster rocket like shown on the right. Instead of a crew, the ERV carries robots that will prepare the Martian outpost for the arrival of humans. II. The ERV uses a minimum-energy transfer to Mars in order to maximize its deliverable payload. III. Immediately after landing on Mars, robots onboard the ERV begin producing some or all of the propellents needed for the mission back to Earth, as well as oxygen and water for the crew. IV. Once the ERV has successfully completed its job producing fuel, oxygen, and water, a habitat module, carrying a crew of four is launched at the next opportunity, approximately 26 months after the launch of the ERV. V. The habitat module travels to Mars on a faster trajectory and lands next to the ERV. At approximately the same time, a second ERV is launched to Mars with the goal of being the return vehicle for the next mission to Mars. This new ERV could also serve as a backup for the first, should the crew finds something wrong with their return craft that could not be discerned from telemetry. VI. The crew spends approximately 550 days exploring the Martian surface, using the fuel, oxidizers, and water provided by the first ERV. VII. When the launch window back to Earth opens, the crew climbs aboard their ERV and leaves the surface of Mars. VIII. The ERV returns the crew quickly to Earth ending the 64 million mile voyage with a splash-down in the Pacific Ocean. Early ERV Sketches ERV Timeline