NASA’s planet-hunting Kepler space

NASA’s planet-hunting Kepler space telescope, hobbled by the breakdown of two crucial parts, is beyond repair, officials announced in a teleconference August 15.

In May the Kepler team reported that two of the four reaction wheels used to turn the spacecraft toward its stellar targets had failed, leaving the telescope incapable of detecting the small dips in starlight that signify the existence of distant planets (SN Online: 5/15/13; SN: 6/15/13, p. 10). Last month engineers forced the faulty wheels back into action one at a time and found high friction levels when each of them spun. Exceedingly high resistance to spin is a death sentence for telescopes that rely on reaction wheels.

Still, last week engineers tried using Wheel 2, the more promising of the two troubled wheels, plus the two functional ones, to direct the telescope. Kepler worked for about six hours before the wheel encountered so much friction that the telescope automatically turned itself off. “The wheels are sufficiently damaged that they cannot sustain spacecraft pointing control for any extended amount of time,” said Charles Sobeck, Kepler’s deputy project manager.

Kepler scientists are now exploring what the telescope can accomplish with just two reaction wheels, and in the fall NASA will determine whether that justifies any of the roughly $18 million allocated to the mission this year. It will be a tough sell: Kepler’s precision focus is what made it an unprecedented astronomical asset.