Planet-hunting Kepler spacecraft in trouble May 15, 2013 -- Updated 2205 GMT (0605 HKT) Where life might live beyond Earth The Kepler space observatory has identified 132 new planets A control wheel has stopped responding, leaving the craft unable to aim precisely at stars "We're not ready to call the mission over," NASA official says (CNN) -- The future of NASA's planet-hunting Kepler space observatory was in question Wednesday after a part that helps aim the spacecraft stopped working, the U.S. space agency said. Controllers found Tuesday that Kepler had gone into a "safe mode" and one of the reaction wheels needed to orient the spacecraft would not spin, Associate NASA Administrator John Grunsfeld told reporters. NASA engineers are trying to figure out whether they can get the balky part back into service or whether they can resume control by another method, Grunsfeld said. "We're not ready to call the mission over," he said. But at roughly 40 million miles from Earth, "Kepler is not in a place where I can go up and rescue it." Another Earth called a certainty The Kepler mission has identified 132 planets beyond our solar system since its launch in 2009, leading scientists to believe that most stars in our galaxy have planets circling them. It has gone into a "safe mode" with its solar panels facing back at the sun, giving controllers intermittent communication with the craft as it spins. Three new planets could host life The probe was built with four reaction wheels and needs three of them -- one for each axis -- to aim its telescope precisely at a distant star, deputy project manager Charlie Sobeck said. One failed in July 2012, leaving it with only two functioning wheels at this time, Sobeck said. Kepler shut itself down after it was pointing in the wrong direction, Sobeck said. He said it was "reasonable to suspect" the failure of the reaction wheel was the cause, but scientists hadn't confirmed that. More news about Kepler The $600 million mission was designed to operate for three and a half to six years. Even if controllers are unable to return it to service, NASA said the mission has produced enough data to keep scientists busy for up to two years. "Another four years would have been frosting on the cake, but we have a nice cake now," said William Borucki, the project's principal scientist. Follow @CNNLightYears on Twitter CNN Correspondent John Zarrella contributed to this report. April 21, 2013 -- Updated 1248 GMT (2048 HKT) In the midst of chaos here on Earth, scientists are finding hope for life on other planets. March 29, 2013 -- Updated 1340 GMT (2140 HKT) In six hours, a person might walk 18 or so miles. By car, it could be 350-plus miles. A commercial airplane might get as far as 3,400 miles. March 21, 2013 -- Updated 1930 GMT (0330 HKT) How cute was our universe as a baby? We now know better than ever: The picture of our early universe just got sharper and tells scientists with greater precision many important facts about how the universe evolved. March 16, 2013 -- Updated 1417 GMT (2217 HKT) Stargazers in North America were delighted to see a highly anticipated comet make an appearance in the March sky. March 16, 2013 -- Updated 1418 GMT (2218 HKT) Breathtaking blossoms nearly the size of our solar system are strewn across the universe -- hundreds of thousands of them. Quasars are, at the same time, among the most fiery monsters. March 13, 2013 -- Updated 1622 GMT (0022 HKT) Curiosity, humanity's most powerful rover to land on Mars, has made a startling discovery: Conditions that could have supported life once existed there. March 2, 2013 -- Updated 1446 GMT (2246 HKT) First a meteor exploded over Russia, followed closely by an asteroid fly-by. Now, two comets are expected to put on a naked-eye spectacle for sky watchers in the Northern Hemisphere. March 5, 2013 -- Updated 1448 GMT (2248 HKT) One man. One woman. Five hundred and one days in an RV-size space capsule. Will they still be speaking when they return? February 28, 2013 -- Updated 1537 GMT (2337 HKT) The meteor that exploded over the steppes of southwestern Russia sent a low-frequency rumble bouncing through the Earth, giving scientists new clues about the biggest cosmic intruder in a century. March 14, 2013 -- Updated 1952 GMT (0352 HKT) It is the first time that we've discovered actual evidence for fresh water on another planet.