Should Humans Go Back to the Moon?

As NASA's plans to returns astronauts to the moon face cancellation, there remain many reasons to go back, researchers said.

The recent dramatic confirmation of water there spotlights how answers on the moon could shed light on the history of life on Earth. It also suggests that resources on the moon could make it helpful as a stepping stone into space.

"It's ironic that we're trying to abandon the moon at the very moment it looks even more inviting than we thought it was," said lunar geologist Paul Spudis at the Lunar and Planetary Institute in Houston.

NASA declined to comment due to the ongoing debate about the future of its human spaceflight program.

Mysteries of the moon

The rocks that have been collected so far from the moon are more than just ornaments in a museum. By going to the moon, "we developed a completely different view of how evolution works and the history of life on Earth that came completely out of left field," Spudis said.

For instance, after the Apollo missions went to the moon, they discovered the meteor impacts that pock its surface could leave behind shocked quartz and other chemical and physical signatures.

"That seemed pretty esoteric, and didn't seem as if it had any practical application, until we found evidence of shocked quartz grains at the Cretaceous-Tertiary boundary, which coincides with the mass extinction event that claimed the dinosaurs," Spudis explained. "Enriched levels of iridium had been found at the boundary, but some had said those might have been due to volcanic activity. The shocked quartz is what really proved an impact, and was totally unexpected."

The moon could hold other secrets regarding our world, including bits of Earth. Tons and tons of rock kicked off the planet by meteor impacts may very well have landed on the moon, carrying secrets not just of the early ages of the Earth but even possibly microbial fossils. "The histories of the moon and Earth are tightly linked, and one illuminates the other," Spudis said.

The moon also serves as a window "into the distant past of all the terrestrial planets ? Mercury, Venus, Earth, Mars,"

For instance, "there are what look like blowholes on the lunar surface ? you have extremely young patches that have virtually no impact craters superimposed on them," Spudis said. "Does that mean there are volatiles venting from the deep interior?"

A telescope on the far side of the moon could also detect signals impossible to see on Earth or even in orbit nearby.

"It would use the moon as a shield against radar noise from Earth, and of course there's no atmosphere to interfere with observations," Spudis noted. Scientists have conjectured that such a telescope could see extraordinarily faint light from mysterious early ages of the universe.

And the very airlessness of the moon could shed light on all the other airless bodies in the solar system.

"We have samples from the moon that can tell us about the same kind of space weathering from solar wind and micrometeorite bombardment that asteroids go through," Taylor said.

Life off Earth

The moon isn't just interesting for the sake of science. It may also be critical to life off Earth.

"It's not about building a moon base so I can go out and perform moon geology, but to harness material and energy resources there to create a sustainable human presence," Spudis said. "If there's any use for human spaceflight at all, it's to create a sustainable presence off-Earth. If you're not doing that, you might as well send machines."

The water at the moon's poles is useful not just for life support, but also to make propellant for spacecraft, he noted. Moreover, the poles may also be home to areas of near-permanent sunlight.

"At the equator of the moon, one can go from 14 days of light to 14 days of darkness," Spudis said. "That not only means that you can't generate solar power from sunlight during the nighttime, but also huge temperature swings from 100 degrees C (212 degrees F) to -150 degrees C (-238 degrees F), which can be hard on equipment we bring up there. In areas always blazing in solar illumination at the moon, it always remains a roughly toasty -50 degrees C (-58 degrees F), so it's easier to control temperature."

The moon is also loaded with fuel for nuclear fusion in the form of helium-3, Taylor explained. "There's a tremendous amount put in the soil by the sun via the solar wind," he explained. "And if you do it effectively, you end up with no radioactivity."

As such, the moon could be fundamental to learning the lessons needed for prolonged life in space. "We'd want to learn how to live off where you are wherever you go," Spudis said.

Although the Constellation program designed as NASA's next human spaceflight program is now in jeopardy, "it's not dead yet ? Congress still has to weigh in," Spudis said. "But whether the U.S. government or some other government or private industry goes back, somebody someday will do it, because it just makes too much sense not to."

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