Mars Direct is a proposed mission architecture, devised by Robert Zubrin and David Baker, that uses current technology to land a small crew on Mars. This plan was summarized in the book, The Case For Mars, written by Robert Zubrin and Richard Wagner. At the time it was proposed, Mars Direct was innovative for its use of in situ resource utilization (ISRU) and for its use of direct launch from Earth to Mars without orbital construction or Mars orbit rendezvous. It also relies on multiple vehicles for improved redundancy. In the book, Zubrin estimated the cost of the mission at $20 - $30 billion. It has inspired several later proposed mission plans, including NASA's Design Reference Mission.
Technically, there is only one Mars Direct design. However, in some circles "Mars Direct" has become shorthand for any mars mission profile which reduces payloads and costs with ISRU and direct launch trajectories.
Scott Davis has written a simulation, based on Zubrin's scenario, called Mars Simulation Project
- Manned mission to Mars
- New Mars Direct, and updated version currently being worked on at the newmars forums.
New Mars Forum Discussions
- The Mars Underground - A movie about Zubrin's Mars Direct released in 2006 (site requires Flash)