![]() Related: NASA's ailing planet-hunting Kepler spacecraft moves closer to new mission Then, about four times a year, the telescope, which is about 15 feet (4.7 meters) long and 9 feet (2.7 m) in diameter, would turn to a different field of view when the sun got too close to its sensors. The mission would use the sun's solar wind to stabilize the telescope for several months at a time. Within a few months, the agency came up with a new mission for the space telescope that it dubbed K2. ![]() At the time, NASA said the telescope was still in good condition otherwise, and investigated alternate mission ideas for the hardware.Īn artist's illustration of NASA's Kepler space telescope hunting for exoplanets. The telescope needs at least three of these devices to stay pointed in the right direction. Kepler was approved far beyond its original mission length and was operating just fine until May 2013, when a second of its four reaction wheels or gyroscopes failed. Related: Gallery: A world of Kepler planets Through this technique, the team unveiled 715 confirmed planets in one release, making the largest batch of planets in a single announcement up to that time. For example, in February 2014 astronomers pioneered a new technique called "verification by multiplicity," which distinguishes multiple-planet systems from multiple-star systems and thus finds many exoplanets at once. So, as Kepler accumulated experience, statistical methods were brought into play. Because apparent star dimming can also take place through means other than exoplanet transits (for example, due to a star's natural variability, starspots, or another star or pair of stars somewhere in the same line of sight), each candidate planet was confirmed through other telescopes, generally by measuring the gravitational "wobble" exhibited by a star in response to a revolving planet.īut Kepler's original mission was not so much to identify individual exoplanets as it was to take a census of as many stars as possible and estimate the percentage of stars that host planets. In the early days, an important part of Kepler operations was eliminating false positives. The $600 million Kepler telescope was launched in 2009 with the expectation that it would operate for a year. Kepler's finds also allow astronomers to begin grouping exoplanets into types, which helps with understanding their origins. The addition of Kepler's sensitive photometry (as well as more sophisticated planet-hunting from the ground) means that astronomers have found more "super-Earths," or planets that are just slightly larger than Earth but have a rocky surface. In the early years of exoplanet hunting, astronomers were best able to find huge gas giants - Jupiter's size and larger - that were lurking close to their parent star. For example, Jupiter passing in front of the sun blocks about 1% of the sun's light Earth blocks less than 0.01%. This precision photometry is necessary to pick up the tiny dimming caused by a planet in front of its star. One of the superpowers of the Kepler space telescope is its ability to measure the brightness of a star to a tiny fraction of a percent. Kepler's third law, named after the astronomer Johannes Kepler (1571-1630), states that if you know the length of a planet's year (its orbital period) and the mass of its parent star, you can calculate its average distance from the star. ![]() Read more: Astronomer Johannes Kepler unlocked the secrets of planetary motion And by looking at the properties of the star we can tell how hot that planet might be." From Kepler's third law we can deduce how far the planet is from the star. By the blocking of that light we can tell how big the planet is compared to the star, and when it repeats we can tell the orbital period. In a lecture at the Carl Sagan Institute at Cornell University, Borucki explained, " looks at over 170,000 stars simultaneously, looking for planets that cross their star and block some light. Kepler was selected at the same time as Dawn, a spacecraft that visited the small worlds Vesta and Ceres. ![]() Kepler was part of NASA's Discovery program, which funds lower-cost spacecraft for exploration of the solar system. ![]()
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