Kepler Mission Down But Not Yet Out

An artist’s rendition of the Kepler spacecraft as it searches distant stars for planets. Credit: NASA/Kepler mission/Wendy Stenzel

Scientists involved in NASA’s Kepler mission reported today that the telescope is in “safe mode” and no longer able to make observations.

John Grunsfeld, associate administrator of NASA’s Science Mission Directorate, said that reaction wheel 4 is not working. Reaction wheel 2 was taken off-line previously, and the telescope needs at least 3 reaction wheels in order to have the precision necessary to make observations.

Kepler looks at stars to observe planetary transits — when a planet passes in front of its star from our point of view.

Grunsfeld said that Kepler is not yet down and out, and they would try to get the wheels working again. Charles Sobeck, deputy project manager, said that the next step is to reduce fuel consumption so they can “park” the vehicle while they figure out what to do next. The telescope is currently orbiting the Sun 40 million miles away from Earth.

William Borucki, Kepler science principal investigator, said that the mission has discovered 2,700 exoplanet candidates, ranging in size from Earth’s moon to larger than Jupiter. 280 of these candidates are Earth-sized, and 850 are twice the size of Earth. Kepler also has taught us that almost every star in our galaxy has planets orbiting them.

Kepler had successfully completed its primary three-and-a-half year mission and entered an extended mission phase in November 2012.

Borucki added that there is about two years worth of Kepler data that still has not been studied, so even if the telescope is no longer operational, he expects many exciting discoveries are still to be made.