Kepler demonstrates that it can still detect planets
Last year, it looked as though the Kepler space probe had nothing to look forward to but the scrap heap. After the failure of two of its reaction wheels, the unmanned spacecraft was incapable of maintaining the precision pointing needed to hunt planets beyond the Solar System. Now, however, NASA has demonstrated that the telescope can still detect exoplanets.
In May 2013, Kepler was a write-off. Launched in 2009, it was designed to seek exoplanets by studying the dip in light coming from other stars as their planets eclipsed them in transit. It proved to be an effective technique, with over 3,000 exoplanet candidates detected and hundreds confirmed.
However, to do its job, Kepler had to keep its gaze fixed on one spot in the sky with minute precision, a precision that was lost when two of its reaction wheels malfunctioned.
That seemed to be the end of the story until NASA and Ball Aerospace engineers figured out that the pressure of sunlight falling on Kepler, which is the primary cause of its instability, could be used to save it.
Dubbed the K2 mission concept, the idea was to angle the spacecraft in such a way that while the sunlight pressed the craft in one direction, the remaining two reaction wheels pressed in the opposite. This way, the forces balanced out and Kepler could remain relatively steady for at least part of its orbit.