HOUSTON – Mars Direct casts aside traditional concepts of travel to the Red Planet by simplifying the process.

He describes it as "living off the land" rather than trying to take everything with you on an expedition.

It differs from the 90-Day Report plan in its simplicity, lower cost and use of available technology.

Instead of relying on space stations and moon bases, everything is launched from Earth.

Zubrin's plan calls for a return vehicle to land before astronauts arrive. It will produce fuel from the Martian atmosphere.

The astronauts arrive in a lander/habitat and spend one year exploring Mars.

At the end of their time on Mars, they board the fueled-up return vehicle for the trip to Earth (see graphics below).

As an added safety feature, a second return vehicle follows the four astronauts aboard the lander. Should they miss landing by the first return vehicle, the second vehicle will land by them and begin the fueling process. Zubrin claims even failing to link up with the second return vehicle wouldn't be a serious problem. The astronauts could wait until another recovery vehicle arrives in a few years.

One of the Zubrin's key points is using existing technology such as simple and proven chemical processes to distill the mostly carbon dioxide Martian atmosphere into methane and liquid oxygen for rocket fuel.