The Voyager probes were originally going to be named Mariner 11 and Mariner 12, respectively. They were then moved into a separate program named Mariner Jupiter-Saturn, and renamed Voyager.

The two Voyager probes were timed and designed to take advantage of a special alignment of the planets that would allow a single spacecraft to reach all of the gas giant planets through a series of gravitational slingshots. The original ambitious plan, called the “Grand Tour Program,” was scaled back to these two probes because of budget cuts, but nonetheless achieved its primary scientific goal with flybys of Jupiter, Saturn, Uranus, and Neptune.