Michael S. W. Keesey (1937- ) is a member of the Solar System Dynamics Group at the Jet Propulsion Laboratory. He began his career at JPL in 1970, and his knowledge of fundamental astronomy and celestial mechanics has been put to good use in the ephemeris development efforts for those planets, comets and minor planets that have been mission candidates or targets of ground-based observations. Citation prepared by D. K. Yeomans, a colleague of the honoree.