Mission News

Kepler Mission Manager Update
Jim Fanson by Jim Fanson, Kepler, JPL Project Manager

The Kepler science team has decided that further refinement of the telescope's focus would significantly improve the mission's science return. The project is therefore proceeding with these adjustments. The telescope's 1.4-meter (55-inch) primary mirror rests on three displacement actuators, much like a three-legged stool. The actuators can be commanded to extend or contract in tiny steps to adjust the mirror in tip, tilt and piston. This adjusts the position of the optical focal surface, the area where light is first focused, relative to the focal plane array, where the imaging detectors are located. An optimized focus of the telescope would make the image quality more uniform across the field of view and minimize the number of imaging pixels required to measure each target star. This would permit more stars to be monitored with less measurement noise, and result in the planet search being more sensitive to smaller planets.