NASA's Kepler mission to search for Earth-sized planets

London, March 4 (ANI): NASA's Kepler mission, which is all set to launch on March 6, will take a long look at the stars in the constellation Cygnus, searching for an Earth-sized planet elsewhere in the Galaxy.

According to a report in Nature News, the Kepler space telescope, which is the single instrument on board Kepler, will hunt for Earth-like 'exoplanets' - planets beyond the Solar System.

Project scientists expect to find hundreds of such worlds, including perhaps the first exact Earth analogue.

Kepler will detect exoplanets by watching them passing, or 'transiting', in front of their star, dimming the starlight temporarily.

It needs to do this at least three times to confirm a planet. If an exoplanet is in an Earth-like orbit, that will take three years.

Of the 342 exoplanets spotted to date, most have been found through the radial velocity method, which picks up slight wobbles in a star's position caused by the gravitational tug of an orbiting planet.

This method is most likely to find large planets close to their stars, however.

Transits are better suited to finding something more like Earth in size and orbit. So far, 58 transiting planets have been found.

The COROT satellite, launched by the French space agency CNES in 2006, has found seven of those transiting planets, and is in many ways a forerunner to Kepler.

Kepler, however, will orbit the Sun rather than Earth, as COROT does, which means it can spend more time looking at the stars.

Kepler also has a bigger telescope: its mirror is 1.4 metres across, compared with COROT's 30 centimetres.

Kepler will stare at 100,000 preselected Sun-like stars 180-920 parsecs away, sending data back to Earth every 30 days.

Scientists will scan those data for planets that might be habitable: not too close to their parent star, nor too far away that liquid water won't exist.

"We all hope this mission will deliver what is promised," said Giovanna Tinetti, a senior research fellow at University College London.

"If Kepler comes up with empty hands, that will be truly astonishing," said Alan Boss, an exoplanet theorist from the Carnegie Institution in Washington DC.

According to William Borucki, the project's principal investigator at NASA's Ames Research Center in Moffett Field, California, even if Kepler doesn't identify any Earth-like planets, that would mean our Solar System really is unique. (ANI)