Asteroids moon's main water supply: Study

London: Water reserves found on the moon are the result of asteroids acting as "delivery vehicles" and not of falling comets as was previously thought, new research has found.

Using computer simulation, the scientists discovered that a large asteroid can deliver more water to the lunar surface than the cumu- lative fall of comets over a billion year period.

At the beginning of the space age, during the days of the Apollo programme, scientists believed the moon to be completely dry.

However, in the1990s, obtaining data from NASA's Lunar Prospector probe, scientists found signs of the presence of water on the moon.

In recent years, lunar missions (the Indian Chandrayan probe, the American LRO, data from the Cassini probe and Deep Impact) have brought scientists new information that there are indeed considerate quantities of water and hydroxyl groups in the near-surface soil on the moon.

The scientists decided to take a closer look at asteroids and found that they consist of initially non-differentiated construction materials of the solar system and contain a rather considerable proportion of water.

One-third of all asteroids that fall on the moon have a velocity of less than 14 km per second just before impact.

When this happens, the major part of the fallen body remains in the crater: 30-40 per cent is left after an oblique impact, and 60-70 per cent after a vertical on