Kepler focal plane assembly

The Kepler focal plane is approximately one foot square. It's composed of 25 individually mounted modules. The four corner modules are used for fine guiding and the other 21 modules are used for science observing. Note that the four fine guidance modules in the corners of the focal plane are much smaller CCDs than the science modules. Each module and its electronics convert light into digital numbers that is analyzed for planet transits


NASA/Kepler mission