Kepler

Ames/JPL-Caltech/NASA

Once feared dead, Kepler catches 104 new exoplanets

Kepler is dead, long live Kepler! NASA’s exoplanet-hunting satellite, which seemed broken beyond repair 3 years ago, today shows it is still very much alive with a batch of more than 100 new worlds that it discovered in 2015. Kepler, designed to stare unblinkingly at one area of the sky for the dimming stars that mark the transit of distant planets, was phenomenally successful after its 2009 launch. For 4 years it gathered data that have been used to identify more than 2300 exoplanets and thousands of potential exoplanets. But in 2012, 3 years into its mission, one of its four reaction wheels (used for pointing the spacecraft at its target) failed. When a second one broke down in 2013, all seemed lost. But Kepler’s ground controllers came up with a clever strategy to keep the spacecraft working with the two remaining reaction wheels, the satellite’s thrusters, and the pressure of sunlight. Kepler could no longer hold steady on its original target; it now moves slowly across the sky following the plane in which the solar system’s planets orbit. NASA rejiggered the mission, and scientists proposed searching for exoplanets around smaller, but closer and brighter stars. An international team of researchers today revealed in The Astrophysical Journal their first catch of 104 exoplanets, all of which have been validated by observations with ground-based telescopes. Because these are around stars closer to Earth, astronomers will be able to follow them in more detail with other telescopes, measuring their masses and probing the composition of their atmospheres for signs of life.