A 12-year-old quest to find planets orbiting other stars gets a big boost this week with the launch of a French-made spacecraft that may help reveal a home-from-home for our descendants.
Bearing a 30-centimetre telescope and two cameras, Corot is designed to hunt for ‘rocky’ planets – the first requirement, along with liquid water and a moderate temperature, for life as we know it.
Corot, pronounced ‘Coreau’, is due to lift off on Wednesday aboard a Russian Soyuz-Fregat rocket from Baikonur, Kazakhstan. The $221 million mission, 75-per cent funded by France's National Centre for Space Studies (CNES), should open up a new front in the search for extrasolar planets.
"It's a small project, launched with few resources, but it is a pathfinder which will show future missions which kind of star to search," said Annie Baglin of the Paris-Meudon Observatory, who is Corot's chief scientist.
In 1995, two astronomers at the Geneva Observatory, Michel Mayor and Didier Queloz, spotted a planet orbiting the star 51 Pegasi, about 50 light years away. It was the first extrasolar planet ever recorded – although, in truth, the sighting was indirect.
Light from 51 Pegasi ‘wobbled’ because it was deflected by gravitation around the large, Jupiter-sized planet. Since then, 209 extrasolar planets have been spotted in 170 solar systems, and the tally is growing by around two planets per month. Besides the popular ‘wobble’ method, astronomers can deduce planets as they cross directly in front of their star — the transit method, used by Corot — and by ‘gravitational lensing’.
Corot is designed to operate for two years and be capable of spotting rocky planets as small as two or three times the size of Earth. It will be followed in 2008 by a more powerful US craft, Kepler, which will be specifically calibrated to look for Earth-sized rocky worlds.
But our primitive chemical rockets are unlikely to take us even to the limits of our own Solar System. So Corot and Kepler may find another ‘Earth’ but we can still only dream of getting there.