The only observer able to view directly the impact of Comet Shoemaker-Levy, it also bolstered evidence of an ocean on Europa and released a probe that descended into the Jovian atmosphere.  
In 1993 it imaged the asteroid 243 Ida and discovered its moon.  The only observer able to view directly the impact of Comet Shoemaker-Levy, it also bolstered evidence of an ocean on Europa and released a probe that descended into the Jovian atmosphere.  For ten points, what space mission was named after the scientist who first observed Jupiter with a telescope?
In 1993 it imaged the asteroid 243 Ida and discovered its moon.  
Galileo