NASA has selected the Kepler Mission, a project based at Ames Research Center, Moffett Field, Calif., as one of the next two new NASA Discovery missions.

Scheduled for launch in 2006, the Kepler Mission will use a unique spaceborne telescope specifically designed to search for Earth-like planets around stars beyond our solar system.

"The Kepler Mission will, for the first time, enable humans to search our galaxy for Earth-size or even smaller planets," said principal investigator William Borucki of Ames. "With this cutting-edge capability, Kepler may help us answer one of the most enduring questions humans have asked throughout history: are there others like us in the universe?"

To date, about 80 extra-solar planets have been discovered. However, these are all gaseous-giant planets similar to Jupiter, which are probably composed mostly of hydrogen and helium and unlikely to harbor life. None of the planet detection methods used so far has the capability of finding Earth-size planets - those that are 30 to 600 times less massive than Jupiter. None of the giants discovered to date has liquid water or even a solid surface.

The Kepler Mission is different from previous ways of looking for planets; it will look for the ‘transit’ signature of planets. A transit occurs each time a planet crosses the line-of-sight between the planet's parent star that it is orbiting and the observer. When this happens, the planet blocks some of the light from its star, resulting in a periodic dimming. This periodic signature is used to detect the planet and to determine its size and its orbit.