astroengine writes: NASA’s planet-hunting Kepler space telescope has shut down due to an apparent problem with its positioning system, suspending indefinitely its science mission, officials said Wednesday. So far, attempts to coax the telescope back into operation have been fruitless. Two of the observatory’s four spinning reaction wheels, needed to properly point Kepler at its targets, are now no longer working. “People are definitely saddened by the loss of another reaction wheel. It certainly is not good news for the mission, which has been performing so well and had so much promise for doing even better,” deputy project manager Charles Sobeck, with the Ames Research Center, told Discovery News.