Water on the Moon

A Franco-American team has just proved that there is water on the surface of our natural satellite.

 

Water on the Moon, a story fit for a suspense-thriller film. Before the first lunar missions, we had not ruled out the idea of finding this precious liquid on our natural satellite, in the form of ice for example.

Alternating pros and cons
But the samples brought back by the Apollo astronauts very much sounded the death knell for this idea. However, hope was given a new lease on life with the Clementine mission (a project run in co-operation between NASA and the American Navy Research Laboratory) in 1994. The radar measurements from this probe can be interpreted as showing the presence of water ice at the lunar poles. Why the poles? Well, there are craters at the poles which are constantly plunged into darkness, the ideal haven for water in the form of ice. But this theory is far from having the unanimous support of the scientific community and their alternating pros and cons foster an aura of mystery. For instance, one line of thinking has recently pointed out the fact that the data from the Japanese Kaguya probe (whose mission ended in June 2009) was hardly encouraging as regards lunar water and yet NASA at the same time launched two robotic spacecraft (LCROSS and LRO, see this article) in the aim of finding this precious liquid!

Half a litre for a football pitch
Another surprise, announced by NASA during a conference on the 24 September 2009, is that the water which has just been found is not in the form of ice, but on the actual surface of our natural satellite. Initial operations were conducted using the American Moon Mineralogy Mapper (M3 or M-cubed). This instrument was fitted on board the Indian probe Chandrayaan-1 (launched in October 2008, it stopped transmitting in August 2009). This spectrometer analyses light in the visible and near infrared ranges. And scientists are able to see the signature of water in the data that they have received. In June 2009, the M3 team, wanting to confirm these findings, asked their counterparts working with the EPOXI probe (a comet probe which was at the time 6 million km from the Moon) to take the same measurement. Olivier Groussin, astronomer with the LAM, the Astrophysics Laboratory in Marseille (OAMP - Marseille-Provence Astronomical Observatory) and member of the EPOXI team, is going to explain all the ins and outs of this astonishing discovery to you on EnjoySpaceTV.

As specified in this video, the water in question probably comes from the interaction between ionised hydrogen H+ (which means that the hydrogen atom has lost its unique electron) carried by the solar winds and molecules of oxygen contained in the lunar soil. Proportions have proved to be very small: a surface area the size of a football pitch would have to be treated to extract half a litre of water! Our natural satellite therefore remains ultra dry according to our terrestrial criteria, but it would certainly not be wise to think that the final conclusion has been reached as the two NASA probes LCROSS and LRO are only at the beginning of their mission. On 9 October 2009, LCROSS is due to carry out a double impact on the Moon near to the South Pole in order to detect any possible traces of water ice. The suspense goes on!

Published on 24 September 2009