Probe Set for Comet Collision

The space probe Deep Impact is 'healthy and ready' for its collision tomorrow with comet Tempel 1 and has already provided images critical to understanding the building blocks of life on Earth, Nasa officials said yesterday.

The spacecraft was still on track to release its coffee-table sized 'impactor' last night. It will smash into the comet at 23,000mph. Although all of the systems appear to be in working order, officials said if the impactor failed to detach from the ship, they had contingency plans to send Deep Impact itself on a collision course.

If all goes well, the crash with the comet - described as 'a jet black, pickle-shaped, icy dirt ball the size of Washington DC' - will be surveyed by the main spacecraft from 310 miles away. It will have 13 minutes to capture images and data before it weathers a blizzard of particles thrown out of the comet's nucleus.

A total of 60 telescopes, in 20 countries, and several orbiting observatories - including the Hubble Space Telescope - will also study the blast which is expected to fire primordial material left over from the formation of the solar system into space. 'These materials have not seen the light of day for 4.6 billion years,' said Jessica Sunshine, a scientist working on the mission. 'That's what we're waiting to see.'