Kepler space telescope loses reaction wheel – exoplanet searching crippled

With the loss of another reaction wheel, he Kepler space telescope has lost the ability to maintain the stable orientation needed for observing stars to detect transits of exoplanets: Kepler Mission Manager Update – NASA.

The managers of the project, however, insist that the mission is not finished and they will still be able to do some interesting science with the spacecraft. There is also a lot of data left to analyze.

Nevertheless, for small planets with orbit periods like the earth or Mars, the longer the observation time the better. A earth sized planet only decreases the star’s light by about 0.01% when it transits across the face of the planet. So the more transits, the better. At least three transits are needed for confirmation of an exoplanet. Kepler began observations in 2009 so there would have been 3-4 transits at an earth size orbit but only 1-2 for a Mars orbit.

There was a NASA briefing this afternoon on the situation and some notes were posted at

Examples:

Alan Boyle : “[Principle Investigator William Borucki] bristles at suggestion that @NASAKepler‘s planet-hunting mission is over. “Reasonable possibility” of resuming data collection.”

Jeff Foust: “Bill Borucki: well on our way to determining “eta Earth”, fraction of stars with Earth-sized planets in hab zones. (key goal of mission)”

Jeff Foust: “Borucki: we’ll declare the mission over when there’s no possibility of getting critically important science.”