NASA's Kepler Space Telescope has officially retired its current space mission, and now researchers are considering other uses for the spacecraft.

"Two of Kepler's four gyroscope-like reaction wheels, which are used to precisely point the spacecraft, have failed," NASA said in a news release.  "The first was lost in July 2012, and the second in May. Engineers' efforts to restore at least one of the wheels have been unsuccessful."

Kepler completed its main mission in Nov. 2012, but NASA extended the spacecraft's stay by four years.  However, the agency could not repair the craft in order to continue its search for Earth-sized exoplanets outside of our solar system that may be able to sustain life.

"Kepler has made extraordinary discoveries in finding exoplanets including several super-Earths in the habitable zone," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington, in a news release. "Knowing that Kepler has successfully collected all the data from its prime mission, I am confident that more amazing discoveries are on the horizon."

NASA engineers conducted performance tests on Aug. 8 to evaluate the spacecraft, which needed three functioning wheels to continue its secondary mission.  Scientists confirmed wheel 2 is broken beyond repair and cannot provide the precision necessary to collect data.   Researchers have begun looking into other alternatives.

"At the beginning of our mission, no one knew if Earth-size planets were abundant in the galaxy. If they were rare, we might be alone," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center in Moffett Field, Calif. "Now at the completion of Kepler observations, the data holds the answer to the question that inspired the mission: Are Earths in the habitable zone of stars like our sun common or rare?"

Click here to read more about Kepler in the full NASA press release.