Kepler runs out of fuel

The US space agency’s Kepler space telescope has run out of fuel and is being retired after nine and a half years, having helped discover more than 2,600 planets, some of which may hold life, officials said Tuesday. The unmanned space telescope, which launched in 2009, revealed that billions of hidden planets are in space and revolutionized humanity’s understanding of the universe, experts said.

Kepler helped astronomers measure potential planets by glimpsing transits, or moments when planets passed in front of their stars.  Kepler showed that “20 to 50 percent of the stars visible in the night sky are likely to have small, possibly rocky, planets similar in size to Earth, and located within the habitable zone of their parent stars,” NASA said in a statement.

“That means they’re located at distances from their parent stars where liquid water -– a vital ingredient to life as we know it -– might pool on the planet surface.” Kepler’s demise was “not unexpected and this marks the end of spacecraft operations,” said Paul Hertz, astrophysics division director at NASA, on a conference call with reporters. Signals that fuel was nearly out were seen two weeks ago.