The Mars Direct concept for a human mission to Mars has been vigorously championed since 1990 by engineer Robert Zubrin, who developed it with fellow Martin Marietta Corporation engineer David Baker. The National Aeronautics and Space Administration (NASA) estimated in 1993 that its plan for Mars exploration, which is called the Design Reference Mission and drew heavily on the Mars Direct approach, could make human footsteps on Mars possible by as early as 2009.

A Clever Synthesis

Mars Direct originated in a Martin Marietta-sponsored effort to develop plans for U.S. President George H. W. Bush's Space Exploration Initiative (1989-1993), which aimed to return humans to the Moon and land the first astronauts on Mars by 2019. Bush's initiative failed because of excessive cost and lack of political support, but it provided an opportunity to revive many old Moon and Mars exploration ideas. Mars Direct, for example, is a cost-saving...