The future of NASA's planet hunting Kepler Space Observatory is in question.
NASA officials say a part that helps aim the spacecraft stopped working -- putting Kepler into "safe mode." Engineers are now trying to figure out whether they can get the part working again or control the spacecraft by another method. The Kepler mission has identified 132 planets since its launch four years ago.
The $600,000,000 mission was designed to operate for 3.5-6 years.