CAPE CANAVERAL, Fla. -- NASA's elite planet-hunting spacecraft has been declared dead, just a few months shy of its 10th anniversary.
Officials announced the Kepler Space Telescope's demise Tuesday.
Already well past its expected lifetime, the 9½-year-old Kepler had been running low on fuel for months. Its ability to point at distant stars and identify possible alien worlds worsened dramatically at the beginning of October, but flight controllers still managed to retrieve its latest observations. The telescope has now gone silent, its fuel tank empty.
"Kepler opened the gate for mankind's exploration of the cosmos," said retired NASA scientist William Borucki, who led the original Kepler science team.
Kepler discovered 2,681 planets outside the solar system and even more potential candidates. It revealed rocky worlds the size of Earth that, like Earth, might harbor life. It also unveiled incredible super Earths: planets bigger than Earth but smaller than Neptune.
NASA's astrophysics director Paul Hertz estimated that anywhere from two to a dozen of the planets discovered by Kepler are rocky and Earth-sized in the so-called Goldilocks zone. But Kepler's overall planet census showed that 20 percent to 50 percent of the stars visible in the night sky could have planets like Earth in the habitable zone for life, he said.
The $700 million mission even helped to uncover last year a solar system with eight planets, just like Earth's system.
"It has revolutionized our understanding of our place in the cosmos," Hertz said. "Now we know because of the Kepler Space Telescope and its science mission that planets are more common than stars in our galaxy."
Almost lost in 2013 because of equipment failure, Kepler was salvaged by engineers and kept peering into the cosmos, thick with stars and galaxies, ever on the lookout for dips in in the brightness of stars that could indicate an orbiting planet.
The resurrected mission became known as K2 and yielded 350 confirmed exoplanets, or planets orbiting other stars, on top of what the telescope had already uncovered since its March 7, 2009, launch from Cape Canaveral.
A Section on 10/31/2018