Moon water may be 'harvested' for Mars missions

With an instrument on board India's lunar mission Chandryaan discovering water molecules on the Moon, scientists are now confident of harvesting water from the lunar surface in the future, which could help sustain lunar astronauts and even propel missions to Mars.

Three spacecraft -- India's Chandrayaan-1 and National Aeronautics and Space Administration's Cassini and Deep Impact probes -- have detected the absorption of infrared light at a wavelength that indicates the presence of either water or hydroxyl, a molecule made up of a hydrogen and an oxygen atom. 

All found the signature to be stronger at the poles than at lower latitudes. Some of these molecules may be created continuously when solar wind protons -- hydrogen ions -- bind to oxygen atoms in the lunar soil.

Comet impacts may also have brought water to the moon. Water delivered by comets or generated by the solar wind could randomly diffuse over time into permanently shadowed craters at the lunar poles, which were recently measured to be colder than Pluto.

"Once it gets in there, it's not going to come out," said Carle Pieters of Brown University in Providence, Rhode Island, lead scientist for the NASA-built instrument that made the Chandrayaan-1 measurements.

So far, the water does not appear to be very abundant -- a baseball-field-sized swathe of lunar soil might yield only 'a nice glass of water', Pieters told New Scientist.

But, if it could be harvested, lunar astronauts could use it as drinking water and split it into oxygen and hydrogen to make rocket fuel for their return journeys. 

That would slash launch costs, since it would reduce the amount of fuel they would need to lug with them from Earth.

Rocket fuel produced on the moon might even help mount a human mission to Mars. 

Because of the moon's weaker gravity, it would take less energy to loft fuel into space for a Mars mission from the lunar surface than it would from Earth.

"It completely changes the spaceflight paradigm," said Paul Spudis of the Lunar and Planetary Institute in Houston, Texas. "It's like building a transcontinental railroad to space," he added.

As to how to extract water that is likely locked up as small concentrations of ice in the lunar soil, Edwin Ethridge of NASA's Marshall Space Flight Center and William Kaukler of the University of Alabama said that microwaves could provide the key.