Kepler telescope declared dead after finding thousands of worlds

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.

Kepler had already been running low on fuel for months, the 9 1/2-year-old. Its ability to point to distant stars and possible identify alien worlds worsened dramatically at the beginning of October, but still managed to retrieve its latest observations. The telescope has gone gone silent, its fuel tank empty.

"Kepler opened the gate to mankind's exploration of the cosmos," said NASA scientist William Borucki, who led the original Kepler science team.

Kepler discovered 2,681 planets outside our solar system and even more potential candidates. It showed us rocky worlds the size of Earth, 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 Kepler's earthquakes are discovered by Earth's so-called Goldilocks zone. But Kepler's overall planet census showed that 20 to 50 percent of the stars could be seen in the living zone for life, he said.

The $ 700 million mission even helped to uncover a solar system with eight planets, just like bears.

"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."

Telescope previously salvaged in 2013

Almost lost in 2013 because of equipment failure, Kepler was saved by engineers and kept peering into the cosmos, with stars and galaxies, ever on the lookout for the planet.

"It was like trying to detect a flea when it was 100 miles away," said Borucki said.

The resurrected mission became known as K2 and yielded 350 confirmed exoplanets, orbiting orbiting other stars, on top of what the telescope had already uncovered since its March 7, 2009, launch from Cape Canaveral.

In all, close to 4,000 exoplanets have been confirmed over two decades, two-thirds of them thanks to Kepler.

Kepler focused on the stars of light-years away and, according to NASA, showed that there is one planet on every star in our Milky Way Galaxy.

Borucki, who dreamed up the mission decades ago, said one of his favorite discoveries was Kepler 22b, a water planet bigger than Earth but it's not too warm and not too cold – the type "that could lead to life."

A successor to Kepler launched in April, NASA 's Tess spacecraft, has its sights on stars closer to home. It's already identified some possible planets.

Tess scientist project Padi Boyd called Kepler's mission "stunningly successful."

Kepler showed us that "we are in the galaxy that's teeming with planets, and we're ready to take a closer look at those planets," she said.

Another longtime spacecraft chasing strange worlds in our own solar system, meanwhile, is also close to death.

NASA's 11-year-old Dawn spacecraft is pretty much out of fuel after orbiting the asteroid. It remains in orbit around Ceres, which, like Vesta, is in the asteroid belt between Mars and Jupiter.

Two of NASA's older telescopes have been hit recently, but have recovered. The 28-year-old Hubble Space telescope resumed science observations last weekend, following a three-week shutdown. The 19-year-old Chandra X-ray Telescope's pointing system also ran into trouble in October. Both cases involved critical gyroscopes, needed to point the telescopes.

Hertz said all the spacecraft problems were "completely independent" and coincidental in timing.

Now 94 million miles from Earth, Kepler should remain in a safe, stable orbit around the sun. Flight controllers will disable the spacecraft transmitters, before bidding a final "good night."