The approval, which followed a recommendation by the agency's Senior Review of its operating missions, means the Kepler space telescope will spend another four years searching for Earth-size planets in the habitable zone -- the region in a planetary system where liquid water could exist on the surface of an orbiting planet -- around sun-like stars in our galaxy, NASA said Wednesday.
Launched in March 2009, the Kepler spacecraft identifies planet candidates by measuring tiny changes in brightness of more than 150,000 stars to detect when a planet transits, or crosses across, the face of the star.
Kepler has so far identified more than 2,300 possible "candidate" planets.
"There is currently no other mission in development that can replace or surpass the precision of Kepler," said Roger Hunter, Kepler project manager at NASA Ames Research Center in Moffett Field, Calif. "This extended mission will afford Kepler a unique opportunity to rewrite our understanding of the galaxy and our place in it."
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