Impactor ejects mighty water mass By Jonathan Amos BBC News science reporter, in Leicester Comets hold materials unchanged since the Solar System's formation The Nasa projectile that slammed into Comet Tempel 1 last year kicked out at least 250,000 tonnes of water. The figure comes from UK/US scientists on the Swift telescope, one of many observatories called on to study the US space agency's Deep Impact event. Swift's X-ray data shows more water was released and over a longer time scale than had previously been thought. Researchers hope the new information will help them understand better the nature and construction...