Scientists have found that glassy volcanic pebbles brought back to Earth by Apollo astronauts in the 1960s and early 1970s have trapped water molecules. The research, published in the journal Nature, used a newly available, highly sensitive type of mass spectrometry. The analysis found water, chlorine, fluoride and sulfur in the volcanic beads formed more than three billion years ago.

The calculations show that at that point, the moon had 750 parts per million of water in its mantle, which is allegedly similar to the water content of Earth's upper mantle. The moon lost at least 95 percent of its water as the molten rock spewed onto the surface and cooled, releasing water vapors into space.

Lead researcher Alberto Saal of Brown University said that his team's initiative was met with skepticism, and they struggled for three years to get funding. Part of the problem was caused by the formerly widespread theory that all rocks of the moon must be dry, because earth's satellite was allegedly formed by a Mars-sized celestial body which sideswiped Earth about 4.5 billion years ago, creating a ring of debris that eventually coalesced into the moon.

Backers of that theory now need to adapt their model to the new findings, but the collision theory will not be abandoned anytime soon because it explains other elements known about moon.

To solve the water and ice mystery regarding the moon, NASA prepares to send in the first phase of its Lunar Precursor Robotic Program (LPRP) this year, the Lunar Reconnaissance Orbiter (LRO), followed by the Lunar CRater Observation and Sensing Satellite (LCROSS). The first is an imagery satellite, while the second is a 2,000 kg vehicle which will explore a permanently shadowed region of a lunar pole in search for ice.

It will do so by observing how the launch vehicle's spent upper stage strikes a lunar crater. NASA will program LCROSS to fly through the debris plume, then some 4 minutes after the Centaur crashes, will itself crash into a different part of the crater.

The moon is Earth's only natural satellite and the fifth largest natural satellite in the Solar System. It has a volume of 0.020 Earths and a mass of 0.0123 Earths. The moon is 1.225 light-seconds away from Earth, at its mean orbital distance.