Last month, NASA declared its Kepler mission to hunt exoplanets at an end when one of the space telescope’s reaction wheels failed. Unable to keep itself pointed in the right direction, it could no longer carry on its hunt for planets beyond the Solar System. That seemed like the end of things, but Keith Horne of the University of St Andrews and Andrew Gould of Ohio State University disagree. They claim that Kepler could still hunt for exoplanets using gravity microlensing to detect how stars with planets distort space.Before its malfunction, Kepler found over 3,000 possible exoplanets with 132 confirmed. The reaction wheel that failed was one of four used by the spacecraft to keep it pointing steady. One of the wheels had failed previously and the loss of a second left the space telescope unable to maintain the precise control needed for hunting exoplanets.
This precise control was needed because Kepler sought exoplanets by measuring how the light from a star would dip as a planet passed in front of it. Kepler needed a high degree of stability and very precise control to record exoplanet transits. The most likely candidates for exoplanets will be close to their stars and so move very quickly across them, meaning that Kepler must remain precisely aligned or its a classic case of “blink and you've missed it.”