What obstacles had to be overcome in development of the mission?
The main obstacles were (a) technical challenges, to achieve instrumentation and systems operations precise enough to detect transits of Earth-size planets, (b) budgetary restrictions and alterations, and (c) procuring highest quality materials and components. Two CCD manufacturers were initially contracted to make CCDs for Kepler mission and ultimately, one of them was able to produce the quality CCDs required for the mission. Budget constraints caused slight shortening of the nominal mission length from 4 years to 3.5 years and also triggered the decision to replace the gimbaled communications antenna with a fixed one.
