Search for other worlds to step up with launch of French planet hunter

Israeli Prime Minister Ehud Olmert (C) smiles as Palestinian President Mahmud Abbas is greeted by his wife Eliza prior to a meeting at Olmert's official residency in Jerusalem Saturday. PHOTO: AFP

Bearing a 30-centimetre (12-inch) 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 170-million-euro (221-million-dollar) mission, 75-percent 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," Annie Baglin of the Paris-Meudon Observatory, who is Corot's chief scientist, told AFP.

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."

Predicted by Einstein in 1912, lensing occurs when a star with a planet passes directly in front of a background star and magnifies the light from that star in a way that reveals the presence of the planet.

Astronomers had broadly expected extrasolar systems to be like our own -- there would be a star with a clutch of smaller "rocky" (i.e. solid) planets orbiting at close range and, much farther out, "gas giants", or huge planets of deep-chilled gas that take years to complete an orbit.