Addressing the International Astronautical Congress here, Griffin said the U.S. Apollo program spent a total of just 27 working days on the moon, which he said is as big as Africa and merits substantially more exploration.

Several space agencies, including some in Europe, say their scientists are much less interested in the moon than in Mars and that, since doing both is beyond their means, are weighing whether to focus on Mars.

Griffin wondered whether those pushing Mars-oriented efforts are fully cognizant of the difficulties of sending astronauts to Mars, and the amount of preparation needed before a mission is pursued.

Griffin said that before any attempt to send a crew to Mars is made, the sponsoring agency or agencies must at least be able to conduct the following mission: Send astronauts to the international space station for a six- or nine-month visit, after which they would be sent to the moon for a similar amount of time, equipped with no additional supplies beyond those sent with them to the station.

Once they completed their moon visit, this same group of astronauts would return directly to the space station for another six- to nine-month visit, again with no resupply.

Only then would they return home. Griffin said this mission would simulate what it will take to send astronauts to Mars and return them home.

"I am not saying that we have to have conducted such a mission, but that we have to be confident in our ability to conduct it before we send astronauts to Mars," Griffin said. "Otherwise, the crew we send to Mars will not come back."

NEWS Source: MSNBC