<P> NASA has characterized Kepler's orbit as "Earth - trailing". With an orbital period of 372.5 days, Kepler slowly falls farther behind Earth (about 16 million miles per annum). As of May 1, 2018, the distance to Kepler from Earth was about 0.917 AU (137 million km). </P> <P> Until 2013 the photometer was pointed to a field in the northern constellations of Cygnus, Lyra and Draco, which is well out of the ecliptic plane, so that sunlight never enters the photometer as the spacecraft orbits . This is also the direction of the Solar System's motion around the center of the galaxy . Thus, the stars which Kepler observed are roughly the same distance from the galactic center as the Solar System, and also close to the galactic plane . This fact is important if position in the galaxy is related to habitability, as suggested by the Rare Earth hypothesis . </P> <P> Orientation is 3 - axis stabilised by sensing rotations using fine - guidance sensors located on the instrument focal plane (instead of rate sensing gyroscopes, eg . as used on Hubble). and using reaction wheels to control the orientation . </P> <P> Kepler is operated out of Boulder, Colorado, by the Laboratory for Atmospheric and Space Physics (LASP) under contract to Ball Aerospace & Technologies . The spacecraft's solar array is rotated to face the Sun at the solstices and equinoxes, so as to optimize the amount of sunlight falling on the solar array and to keep the heat radiator pointing towards deep space . Together, LASP and Ball Aerospace control the spacecraft from a mission operations center located on the research campus of the University of Colorado . LASP performs essential mission planning and the initial collection and distribution of the science data . The mission's initial life - cycle cost was estimated at US $600 million, including funding for 3.5 years of operation . In 2012, NASA announced that the Kepler mission would be funded until 2016 at a cost of about $20 million per year . </P>

Which method does the kepler space telescope used to detect extrasolar planets