A comet-chasing spacecraft is set to blast-off on Wednesday from Cape Canaveral Air Force Base in Florida.

The NASA craft, CONTOUR (Comet Nucleus Tour), will fly within 100 kilometres of two comets during its four-year mission, capturing surface images and measuring the chemical composition of each comet’s nuclei.

CONTOUR will rendezvous with comet Encke on 12 November 2003, and then comet Schwassmann-Wachmann 3 on 19 June 2006. NASA scientists say the mission could provide valuable clues to the formation of the solar system.