Kepler, NASA's planet-finding space telescope, is in serious jeopardy of being put out of commission after one of its reaction wheels – which allow astronomers to point the device – suffered a serious malfunction, the agency said Wednesday.
Since being launched in 2009, the telescope has discovered at least 132 planets, with another 2,740 "planet candidates" also spotted. Last month, researchers at Notre Dame University found the two "most Earth-like" planets ever discovered, about 1,000 light years away.
Kepler was put into "safe mode" Tuesday after its fourth wheel stopped responding.
The spacecraft has four reactor wheels, but after the failure of one last year, the latest setback means that the telescope may never again return to a "science mode."
"I wouldn't call Kepler down and out just yet," John Grunsfeld, associate administrator of NASA's science mission directorate told reporters Wednesday. "Unfortunately, Kepler is not in a place where I or any other astronaut can go up and rescue it."
Grunsfeld said that the development isn't completely unexpected.
"This is something we've been anticipating for a while, we've seen technical indications there was problems with that wheel," he said. "We're going to see if it's possible to see if we can eventually return to a science mode."
Kepler was the first NASA mission designed to find Earth-sized planets in their solar systems' habitable zones – the area that is close enough from a star to have liquid water, but far enough away to keep it from being too hot to support life.
When launched, the telescope was planned to only last for about 3.5 years, but its mission was extended after it proved to be extremely successful. Last year, the telescope's mission was extended to 2016.
"We're not ready to call the mission over, but by any measure it's been a spectacular mission," he said.
Charles Sobeck, deputy project manager at Ames Research Center, said that the spacecraft is currently conserving fuel and can be parked for several years until it runs out of fuel. Borucki said it's currently in an "oasis" state while astronomers try to figure out next steps.
"The eventual performance we'll get to, we don't know at this point in time," he said.
NASA says they have about two years worth of Kepler data to comb through, so discoveries might still be made.
The telescope monitors a small section of the night sky that encompasses more than 150,000 star sequences. It looks for shadows cast on the stars, which are cast by orbiting planets.