'Unambiguous Evidence' of Water on the Moon Found

Until not long ago, experts believed that the Moon was not the most likely place in the solar system where one would find liquid water. In fact, measurements of lunar soil samples, brought back by Apollo-mission astronauts, have shown that, on average, only about 32 ounces of water could exist in theory within a ton of the material. In time, it became established knowledge that water could exist at the satellite's poles, in hidden craters, but that the rest of the surface was bone-dry. However, studies conducted with a number of different space probes seem to paint a different picture, Space reports.

Discovering actual water on the Moon, such as, for instance, observing it directly inside a crater, would make human exploration more worthwhile, and also sustainable. Such reserves could power up future lunar bases, where astronauts could study the samples they collect on the spot, without having to send them to Earth. Still, it remains clear that, for the most part, the planet's natural satellite is drier than any desert back on Earth, experts say.

Just recently, NASA's Lunar Reconnaissance Orbiter (LRO) probe discovered signatures of water or hydroxyl in deep, dark craters on the Moon's South Pole. The find comes just weeks before the planned crash of the Lunar CRater Observation and Sensing Satellite (LCROSS) instrument, which will further investigate if water-ice exists in this remote location. The craft will first dump a spent Centaurus upper stage into the Cabeus A crater, and, after it photographs the collision, it will be driven itself in the same crater, to augment the results.

“If the water molecules are as mobile as we think they are – even a fraction of them – they provide a mechanism for getting water to those permanently shadowed craters. This opens a whole new avenue [of lunar research], but we have to understand the physics of it to utilize it,” Brown University planetary geologist Carle Pieters says. He is the author of one of the three studies on lunar water, appearing in tomorrow's issue of the top journal Science.

In recent times, three craft have also unproven the idea that the Moon has no water on locations other than its craters. India's Chandrayaan-1, NASA's Cassini spacecraft, and NASA's Deep Impact probe have all measured spectral signals coming from either water or the hydroxyl group. The latter is a chemical that features a single atom of hydrogen along an oxygen atom, instead of the two hydrogen atoms that can be found in water.