NASA, THE American space agency, plans to fire a huge copper bullet into the surface of a comet, gouging out a crater seven storeys deep. The Deep Impact project aims to find out more about what makes up the matter at the core of a comet.
When the Deep Impact spacecraft approaches the comet P/Tempel 1 on 4 July 2005, it will release a half-ton projectile that will strike the comet at a speed of 10 kilometres a second, resulting in the release of "pristine" ejecta from inside the comet into space.
Owing to a production error, the authorship of last week's article on the moon, `Stranger in the Night', was wrongly attributed. Apologies to David Whitehouse, who wrote the piece