The biggest factor hanging over human settlement of other worlds is the question of water. We need it to drink, we need it to cultivate food, we need it for fuel (indeed, we need it for the first lunar microbrewery); pretty much every human activity requires water. Supplies of water could be ferried from Earth to the Moon, but that would be prohibitively expensive and ultimately futile. For us to live on the Moon or further afield, H2O needs to already be there.
Ever since the Apollo lunar landings when samples of rock were transported to Earth we’ve been searching for the mere hint of this life-giving molecule. There have been indications that the lunar regolith may indeed contain trace amounts of the stuff, but on the whole, scientific endeavour has yet to return evidence of any large supply of water that could sustain a colony.
Up until now, scientists haven’t been able to seriously entertain the thought of water on or near the surface of the Moon, apart from in the depths of the darkest impact craters. However, data from the recently deceased Indian Chandrayaan-1 mission has supported data taken by the Cassini probe (when it flew past the Moon in 1999 on its way to Saturn) and NASA’s Deep Impact probe (which made several infrared observations of the lunar surface during Earth-Moon flybys on its way to the 2010 rendezvous with Comet 103P/Hartley 2). Both Cassini and Deep Impact found the signature of water and hydroxyl, and now, a NASA instrument on board Chandrayaan-1 reinforces these earlier findings.
The NASA-built Moon Mineralogy Mapper (M3) on board the Indian satellite detected wavelengths of light reflected off the surface that indicated hydrogen and oxygen molecules. This is convincing evidence that water is either at, or near, the lunar surface. As with the previous measurements, the water signal gets stronger nearer the lunar poles.
So what does this mean for the future of manned space exploration? Although water has been detected, this doesn’t mean there are huge icy lakes for us to pitch a Moon base and pump out the water. In actuality, the signal indicates water, but there is less water than what is found in the sand of the Earth’s deserts (you can pack away the drinking straws now).
“It’s still pretty damn dry, drier than anything we have here. But we’ve found this dynamic, ongoing process and the moon was supposedly dead,” University of Maryland senior research scientist Jessica Sunshine told Discovery News. “This is a real paradigm shift.”
If there are widespread water deposits (despite the low concentrations), even in regions constantly bathed in sunlight, there is huge potential for water deposits in those mysterious, frozen craters. Interestingly, these measurements indicate that the water may not have just been deposited there by comets; the interaction between the solar wind and the existing lunar mineralogy could be a mechanism by which lunar ice is constantly being formed.
“Every place on the moon, at some point during the lunar day, though not necessarily at all times, has water and OH [hydroxyl],” Sunshine said.
We may see self-sufficient lunar colonies yet. But the saying “getting blood out of a stone” should probably be replaced with “getting water out of the lunar regolith”…
Next up is NASA’s LCROSS mission that is scheduled to impact a crater in the south pole on October 9th. Analysis from the impact plume will supplement this positive Chandrayaan-1 result, hopefully revealing yet more water in this frozen region.