THERE are two types of asteroids in space – those that contain water and those that don’t. But 97 per cent of the meteorites that crash-land on Earth are dry. What happens to the wet ones?
They were thought to disintegrate on hitting the atmosphere, which would explain the source of the 30,000 tonnes of asteroid dust that falls to Earth each year. But the first experimental tests of this theory are prompting a rethink.
Kazushige Tomeoka, from Kobe University in Japan, and his team fired bullets at meteorites of each type. The hydrated rocks fractured more readily, but unexpectedly, this disintegration was explosive (Nature, vol 423, p 60). The researchers now believe that wet asteroids colliding in space are more likely to produce clouds of dust than chunks of rock that could fall to Earth as meteorites.
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