The trip from Earth to Jupiter, the probe’s exploration of the Jovian atmosphere, and an Orbiter tour consisting of 11 orbits of Jupiter constituted Galileo’s Prime mission. On Jupiter arrival Day (7 December 1995), the Galileo spacecraft was given a gravity-assist from Io and then subjected to the Jupiter orbit insertion (JOI) maneuver, which slowed the spacecraft down and let it be “caught” by the planet. These two actions placed the Orbiter on its proper trajectory to tour the Jovian moons. The Jupiter orbit insertion maneuver involved an orbit around the planet, which is referred to as the spacecraft’s “zeroth” orbit. The spacecraft’s “first,” and by far longest, orbit around Jupiter followed the JOI and lasted nearly seven months. On 27 June 1996, this initial orbit culminated in a cl