The Moon may hold much more water than originally thought, according to new data recovered by a lunar probe.
US and French scientists have revised upwards the amount of water they believe lies hidden at the Moon's frigid polar regions. They now calculate that there may be up to 10 times more water than suggested in earlier conservative estimates.
And significantly, scientists analysing data collected by the Lunar Prospector satellite in orbit 100 km above the lunar surface believe the water is not spread thinly as originally thought. It is possibly localised, existing as deposits of solid ice just under the surface.
Lunar Prospector was launched in January of this year, the first NASA Moon mission in 25 years. The first major release of Prospector data came last Friday in the journal, Science, with scientists from the US Department of Energy's Los Alamos National Laboratory writing as lead authors on four of the papers with significant contributions from the Observatoire Midi-Pyrenees in Toulouse. There were also papers from other researchers including a group from the University of California, Berkeley.
Prospector had been returning data since mid-January and initial results in March suggested that water was deposited like a thin frost throughout the lunar soil at the poles, according to Dr Bill Feldman of Los Alamos. "As we've gotten more data we've found that it's not spread out as we first assumed, but concentrated. It's localised in spots near the poles and it has to be buried, about half a metre or so."
There could be up to three billion metric tonnes of water at the two poles, he estimated. It would be much easier for visitors from the Earth to retrieve it if it was found in chunks rather than as a thin, widely dispersed frost.
Water would be a major find for any lunar explorer. It could be purified and drunk but more importantly water is easily split into its constituents, hydrogen and oxygen. This could yield both a breathable atmosphere but also feedstock for electricity producing fuel cells and rocket fuel. The water amounts are inferred from measurements of hydrogen in the lunar soil and the hydrogen signature is taken using Lunar Prospector's on-board neutron and gamma ray spectrometers. The spectrometers measure the numbers and energies of particles or photons coming up from the lunar surface.
These arise when cosmic rays coming from space hit the surface, striking elements in the soil and knocking out neutrons or gamma ray photons. The spectrometers read the distinct energy levels which scientists can use to identify the elements found in the soil below. "The data shows clearly where the hydrogen is," Dr Feldman said, and where there is hydrogen, water is predicted to lie below.
Scientists believe that the Moon's water supplies were delivered by comets during heavy bombardments of the entire solar system millions of years ago. The Earth was also at the receiving end of these impacts, with such a collision blamed for the extinction of the dinosaurs.