Voyager

The twin Voyager spacecraft were designed to perform close-up observations of the atmospheres, magnetospheres, rings, and satellites of Jupiter and Saturn. The mission was originally designed to make a "Grand Tour" of all five outer planets, but was descoped due to funding limitations. However, following its planned encounter with Saturn, Voyager 2's planetary mission was extended, and it was placed on a trajectory to allow flybys of Uranus and Neptune.