NASA’s Galileo spacecraft became the first spacecraft to orbit Jupiter when it arrived there on 7 December 1995. The mission had launched from Space Shuttle Atlantis in 1989 and used gravity assists at Venus and Earth to build enough speed for the outer Solar System.
Galileo studied Jupiter’s atmosphere, magnetosphere, rings, and large moons. It also released an atmospheric probe that descended into Jupiter’s clouds and measured temperature, pressure, composition, and winds.
The spacecraft produced important evidence that Europa, Ganymede, and Callisto may contain subsurface oceans. Galileo operated for almost eight years in the Jovian system. Its mission ended in 2003 when controllers deliberately directed it into Jupiter to prevent an accidental impact with Europa, which scientists wanted to keep free from possible biological contamination.