So you want to go looking for other Earth-like planets and theuniverse is big. How do you start? Where do you look? “You select areaswhere you have a lot of solar-type stars,” says Malcolm Fridlund, aproject scientist for the European Space Agency (ESA). “They’re mostlikely to have planets like our solar system’s.” Fridlund helped designCOROT (for convection, rotation, and planetary transits), ESA’s earlyentry in the race to find rocky, Earth-like planets outside our solarsystem.

Launched late last year, COROT is collecting information aboutdistant planets as well as measuring cosmic stellar vibrations, whichprovide clues to the interiors of distant stars. In late April, thesatellite is scheduled to execute a slow, steady about-face to look thecenter of the Milky Way straight in the eye and scan the dense crowdsof stars there for terrestrial planets. “COROT is like a fisherman whohas a giant net and catches fish from time to time,” says LaurentKerjean, who runs COROT’s system tests.

Over 150 days this summer, COROT will capture data from an area ofsky roughly equal to the size of the constellation Orion. Then it willturn and continue its hunt in the opposite direction. By the end ofCOROT’s mission, which could last up to three years, investigatorsexpect to have searched for rocky planets around 50,000 to 60,000stars, providing the first good stats on the abundance of such worlds.

COROT is the first—and at $175 million, the cheapest—planet-seekingmission to get off the ground. NASA’s first Earth seeker, the Keplermission, is scheduled for liftoff in 2009, and both NASA and ESA havescheduled more sophisticated missions for the next two decades. “Wedon’t know how common Earth-like planets are in our big universe. Theycould be extremely rare,” Fridlund says. On the other hand, “if COROTpicks up rocky planets, then that means that Earth-like planets arecommon in the galaxy and that the conditions under which life couldarise might not be that rare.”