With so many exciting celestial bodies in our solar system and beyond, it's easy to take the moon for granted. Sure, NASA crashed a probe into the lunar surface for science recently, but no human being has set foot on the moon since Apollo 17 in December 1972.
Now Ian Crawford of Birkbeck College in London and his colleagues have co-authored a paper making the case for a return manned mission to the moon, to augment the many remote-sensing spacecraft sent into lunar orbit over the last ten years.
So, what did they come up with? Well, for starters, the moon could be an excellent source of Earth rocks, dating back to its early history when it was being constantly bombarded by assorted asteroids and comets. Some of the material ejected into space from those impacts wound up on the lunar surface, making the moon a potential gold mine in terms of studying the chemical composition of early Earth -- and possibly even the prebiotic origins of life on our planet.
Furthermore, this could shed light on the process of terrestrial planet formation from the earliest days of our solar system in general. As Crawford et al point out in their paper (PDF)::
"The lunar surface provides a platform for geophysical instruments (eg seismometers and heat flow probes) to probe the structure and composition of the deep interior... [T]he moon's outer layers also preserve a record of the environment in the inner solar system ... throughout solar system history much of which is relevant to understanding the past habitability of our planet."
Then there are the potential natural resources on our humble satellite. The moon's lunar soil is chock-full of helium reserves, thanks to the solar wind. We just need to figure out how to harvest this critical element with an economically viable process.
In 2009, NASA bombed the moon -- part of its Lunar CRater Observation and Sensing Satellite (LCROSS) mission -- and observed grains of water ice in the remnants of the resulting plume, as well as light metals such as sodium and mercury, and volatile compounds like methane, ammonia, carbon dioxide, carbon monoxide and hydrogen. Where you have water ice, you have a potential mother lode for lunar prospecting of hydrogen.
Our moon could also be a source for rare earth elements, such as europium and tantalum, which are in high demand on Earth for electronics and green energy applications (solar panels, hybrid cars), as well as being used in the space and defense industries.
Scientists know that there are pockets of rare earth deposits on the moon, but as yet they don't have detailed maps of those areas. Potassium, phosphorus and thorium are other elements that lunar rocks have to offer a potential mining venture.
Crawford et al also argue that the lunar surface is ideal for certain astronomical observations, namely,
exploring the universe via the regime of ultra-low-frequency radio waves. Earth-based instruments can't probe that regime, because those radio waves are absorbed by the ionosphere.
But the far side of the moon is pretty much radio-silent, so setting up an array of antennas to build a lunar radio telescope would enable astronomers to view the cosmos in this as-yet-unmapped regime. It's significant because ultra-low-frequency radio waves could shed light on the universe's "Dark Age" -- that period when it was just a few million years old, before the first stars and galaxies formed.
And if we're going to have radio telescopes, mining operations, and geological studies taking place, it just makes sense to send a few humans to oversee all those projects, right? Crawford et al think this provides an excellent opportunity study more long-term effects of microgravity of the human body, as well as inspiring advances in cutting-edge lunar life support systems.
Or maybe, 40 years from now, we'll have the technology to station clones on the lunar surface to man all that infrastructure, so human beings can stay home -- or head further afield to Mars. Suddenly the premise of the 2009 sci-fi film, Moon, doesn't seem nearly so far-fetched.