spacetoday.net: Reaction wheel fails on Kepler, putting mission's future in question

Posted: Thu, May 16, 2013, 7:50 AM ET (1150 GMT)
Kepler spacecraft illustration (NASA/Ames)

A second reaction wheel on NASA's Kepler spacecraft has failed, forcing agency officials to consider alternative missions for the exoplanet-hunting spacecraft. NASA reported Wednesday afternoon that Kepler went into safe mode on Tuesday, and when recovering the spacecraft found that one of the spacecraft's four reaction wheels was not working. The reaction wheels are used to keep the spacecraft properly oriented, and three are needed to operate the spacecraft normally; another reaction wheel had failed last year. With only two wheels working, Kepler cannot continue its mission to look for extrasolar planets, but project officials are looking at ways they can possibly recover one of the failed wheels. NASA will also look at alternative uses of Kepler, such as looking for asteroids, that do not require the same pointing precision and could be done with the remaining two wheels plus thrusters. Kepler, launched in 2009, has already completed its prime mission, and project scientists said there was still a large volume of data from the spacecraft that they had yet to fully analyze.