GeoViz v2.0
GeoViz (GV) is a web-based tool for graphically planning spacecraft observations. It shows planets, stars and FOVs (fields-of-view) on the sky. It is robust and accurate, and is accessible through a flexible web-based interface.
GV was originally written by Dr. Henry Throop for the New Horizons mission, and has been subsequently been used by other missions, including Rosetta, Cassini, Messenger, MAVEN, Juno, JUICE, LRO, Voyager 1+2, and Galileo.