The lifetime of Kepler, the great exoplanet finding machine, may be cut prematurely short if efforts to save a balky reaction wheel fall short:

• Kepler glitch suspends NASA’s search for new planets – sen.com
• Kepler Mission Manager Update – NASA
• Twitter / mrtommyb: “To be clear, we are resting the spacecraft as a precaution. There is no evidence to suggest that a reaction wheel failure is imminent.”