Scientist-astronaut Harrison H. Schmitt is photographed working beside a huge boulder at Station 6 (base of North Massif) during the third Apollo 17 extravehicular activity (EVA) at the Taurus-Littrow landing site. Credit: NASA

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.

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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.

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“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.”

“The science of the moon has just been scratched,” Schmitt added. “We’ve

hardly explored the moon.”

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For example, new studies of the rock and soil samples retrieved during the six Apollo expeditions to the moon have raised questions about how Earth’s companion formed.

The prevailing theory has been that a Mars-sized object bashed into Earth during the solar system’s early days, causing debris to shoot into space. The material eventually collected into what became the moon.

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Computer models laying out the impact scenario, however, can’t account for traces of water and other lightweight elements found inside volcanic glass beads in the lunar samples. The extreme heat of the collision likely would have vaporized these volatiles.

More clues to the moon’s formation, as well as Earth’s early history, may lie inside a massive impact crater on the moon’s south pole. The so-called Aitken basin juts more than 8 miles into the lunar crust, perhaps even down to the mantle.

“Aitken may have penetrated deep enough into the moon to give us information that ultimately would feed into answering this question,” Schmitt said.

In addition to science, the moon presents a relatively nearby place to test equipment and develop technologies needed to go to Mars, a long-term objective of the U.S. space program. Moon missions also would enable a new generation of workers to learn to operate in deep space.

“The people who know how to work in deep space are my age now, if not older,” said Schmitt, 77. “We need young people to get the same kind of experience.”

A National Research Council report released this week shares Schmitt’s concerns.

“We see little evidence that the current stated goal for NASA’s human spaceflight

program — namely, to visit an asteroid by 2025 — has been widely accepted as a

compelling destination by NASA’s own workforce, by the nation as a whole, or by

the international community,” the report said.

Schmitt presented research about ongoing studies of the 40-year old Apollo moon samples at the American Geophysical Union conference in San Francisco this week.