List of missions to the outer planets



A total of nine spacecraft have been launched on missions that involve visits to the outer planets; all nine missions involve encounters with Jupiter, with four spacecraft also visiting Saturn. One spacecraft, Voyager 2, also visited Uranus and Neptune. The nine missions include two, Ulysses and New Horizons, whose primary objectives were not outer planets, but which flew past Jupiter to gain gravity assists en route to a polar orbit around the Sun (Ulysses), and to Pluto (New Horizons). Pluto was considered a planet at the time that New Horizons launched, but was reclassified as a dwarf planet. Cassini–Huygens also flew past Jupiter for a gravity assist on its mission to explore Saturn.

Only three of the missions to the outer planets have been orbiters: Galileo orbited Jupiter for eight years, while Cassini orbited Saturn for thirteen years. Juno has been orbiting Jupiter since 2016.

Jupiter
Eight spacecraft have been launched to explore Jupiter, with two other spacecraft making gravity-assist flybys.

New Horizons, although eventually targeting Pluto, used Jupiter for a gravity assist and had an extensive almost half year observation campaign of Jupiter and its moons (hence it is counted in the eight). {{legend|#cccccc|Gravity assist, destination elsewhere}}

Saturn
Four spacecraft have visited Saturn; Pioneer 11, Voyager 1 and Voyager 2 made flybys, while Cassini–Huygens entered orbit, and deployed a probe into the atmosphere of Titan.

Uranus
Voyager 2 is the only spacecraft to have visited Uranus, making a single flyby as part of its grand tour of the outer planets.

Neptune
Voyager 2 is the only spacecraft to have visited Neptune, making a single flyby as part of its grand tour of the outer planets.

Pluto and trans-Neptunian objects
New Horizons is the only spacecraft that visited dwarf planet Pluto (in 2015) and the trans-Neptunian object 486958 Arrokoth (in 2019).

Major milestones
† First to achieve
 * Legend