BOULDER - Students and staffers at the University of Colorado's Laboratory for Atmospheric and Space Physics worked around the clock to get the disabled Kepler space telescope to its current "safe mode" state in space.

The Kepler spacecraft has suffered a disabled reaction wheel, a device that keeps it oriented in a particular direction, NASA said Wednesday. Boulder-based Ball Aerospace and Technologies Corp. built the more than $300 million Kepler spacecraft, which hunts for planets that have atmospheric conditions similar to Earth's. LASP workers operate the NASA mission for Kepler.

LASP workers were able to get the spacecraft into "safe mode" on Wednesday night, which keeps it pointed in a direction that allows its solar arrays to collect power from the sun, said Bill Possel, director of mission operations and data systems at LASP.

Since the spacecraft has a limited amount of fuel, keeping the solar arrays charging is a critical piece of the mission, Possel said. Now that the immediate threat from power loss is over, engineers are looking at ways to get the disabled reaction wheel back on track, possibly by finding a way to spin all of the craft's reaction wheels in the opposite direction, Possel said.

"It's not looking good, but there's always the chance that we can come up with some way of recovering from this reaction-wheel failure," Possel said. "There are many ... possibilities we could try."

The Kepler spacecraft could stay in the current "safe mode" configuration for many years, Possel said. No timeline has been set about the future direction of the NASA program.

The Kepler mission was designed to run for three and a half years, and the spacecraft has been working for four years so far, Brown said. NASA officials are expected to work on the reaction wheel problem for the next three or four months before making a decision about what the next step should be, she said.

Less than a month ago, researchers reported that Kepler had discovered three possible Earth-like planets in other star systems in space. Two of the Earth-like planets were designated as Kepler-62f and Kepler-62e. They orbit the same star system.

The third Earth-like planet, Kepler-69c, orbits a second star system. The planets orbit in zones of their respective stars where liquid water and life is possible, although the masses and composition of the planets have not been determined, NASA said.

The planet Kepler-62f is about 40 percent larger than Earth and is thought to be a rocky world, much like Earth, according to NASA. The planet Kepler-62e is about 60 percent larger than Earth and orbits at the inner edge of a "habitable" zone of Kepler 62, which is classified as a K2 dwarf star.

Kepler-69c is about 70 percent larger than Earth and orbits a star similar to the sun.

Because so much data has been coming back to Earth from Kepler, researchers are two years behind in analyzing all of the information that's been gathered, Possel and Brown said.

"There's a lot more science to come from Kepler, and more discoveries to come with the information they've got already. The mission isn't over," Brown said.

Reaction wheels have been limiting factors in past spacecraft vehicles, since they're constantly spinning and creating friction, Possel said. A first reaction wheel failure happened on the Kepler spacecraft about nine months ago, but it could still function with three wheels, he said.

Possel compared the spacecraft reaction wheel failure to parts wearing out on a car.

"We're trying to see what kind of science we can do if we're stuck with only having two reaction wheels," Possel said. "It's certainly disappointing at this point, but I don't want anybody to give up hope yet."
LASP crews normally have contacts twice a week with Kepler, but workers from LASP and Ball worked day and night Tuesday and Wednesday to get the spacecraft into "safe mode," Possel said. Without two reaction wheels, the spacecraft's telescope cannot be accurately pointed to measure planets orbiting stars, he said.

Kepler was launched in March 2009 and already has discovered more than 2,700 potential new planets. Of those, about 115 have been identified, according to NASA.

Ball Aerospace was chosen to build the telescope because of its success building instruments for previous NASA missions, including the Hubble and Spitzer Space Telescopes, and the Deep Impact mission, NASA said.