Apollo astronaut and geologist Harrison "Jack" Schmitt doesn't buy the prevailing theory that the moon formed from pieces of Earth that were shot into space after a giant impact.
Instead, Schmitt suspects Earth's gravity captured a smaller body that had built itself up in a nearby orbit.
Additional evidence may be found inside a deep crater on the moon's south pole, one of several areas Schmitt, now a professor at the University of Wisconsin, advocates exploring, not only for science, but to prepare for human missions to Mars.
As a follow-on program to the International Space Station, the moon fell out of favor as a destination for the U.S. human space program due to high costs. Instead, the Obama administration wants NASA to plan for a manned mission to an asteroid by 2025, an interim milestone toward an eventual human expedition to Mars.
Schmitt, a member of the last Apollo crew that blasted off 40 years ago on Dec. 7, 1972, believes that's a mistake.
"I think an asteroid is a diversion," Schmitt told Discovery News. "If the ultimate goal is to get to Mars, you have a satellite only three days away that has a great deal of science as well as resources."