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 are not related to the outer planets, but which flew past Jupiter to gain gravity assists en route to a polar orbit around the Sun, and Pluto—at the time of its launch considered an outer planet—respectively. 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.
Summary
Jupiter
Six spacecraft have been launched to explore Jupiter, with spacecraft making gravity-assist flybys.New Horizons, although eventually targeting planet Pluto, used Jupiter for a gravity assist and had an extensive almost half year observation campaign of Jupiter and its moons.
| Spacecraft | Launch Date | Operator | Mission | Outcome | Remarks | Carrier rocket |
| Pioneer 10 | NASA United States | Flyby | Closest approach at 02:25 UTC on 4 December 1973 | Atlas SLV-3C Centaur-D | ||
| Pioneer 11 | NASA United States | Flyby | Closest approach at 05:22 UTC on 3 December 1974, later flew past Saturn | |||
| Voyager 2 | NASA United States | Flyby | Closest approach at 22:29 on 9 July 1979, later flew past Saturn, Uranus and Neptune | Titan IIIE Centaur-D1T | ||
| Voyager 1 | NASA United States | Flyby | Closest approach at 12:05 UTC on 5 March 1979, later flew past Saturn | Titan IIIE Centaur-D1T | ||
| Galileo | NASA United States | Orbiter/Atmospheric | Atmospheric probe entered atmosphere at 22:04 UTC on 7 December 1995 and operated for 57 minutes; main spacecraft entered orbit at 00:27 UTC on 8 December. Spacecraft was deorbited on 21 September 2003, impacting Jupiter's atmosphere at 18:57:18 UTC. | STS-34 / IUS | ||
| Ulysses | NASA United States / ESA | Gravity assist | Flyby on 8 February 1992 to reach a high-inclination heliocentric orbit. Also made a distant incidental flyby on 4 February 2004 | STS-41 / IUS | ||
| NASA United States / ESA | Gravity assist | Flyby on 30 December 2000 en route to Saturn | Titan IVB Centaur-T | |||
| New Horizons | NASA United States | Gravity assist Major observation campaign from Jan-June | Flyby on 28 February 2007 en route to Pluto | Atlas V 551 | ||
| Juno | NASA United States | Orbiter | Entered orbit 4 July 2016 | Atlas V 551 |
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.| Spacecraft | Launch Date | Operator | Mission | Outcome | Remarks | Carrier rocket |
| Pioneer 11 | NASA United States | Flyby | Closest approach on 1 September 1979 at 16:31 UTC | |||
| Voyager 2 | NASA United States | Flyby | Closest approach at 01:21 UTC on 26 August 1981, later flew past Uranus and Neptune | Titan IIIE Centaur-D1T | ||
| Voyager 1 | NASA United States | Flyby | Closest approach on 12 November 1980 at 23:45 UTC | Titan IIIE Centaur-D1T | ||
| NASA United States | Orbiter | Entered orbit 1 July 2004; mission concluded on September 15, 2017 | Titan IVB Centaur-T | |||
| ESA / ASI Italy | Titan lander | Deployed from Cassini; landed on Titan at 10:13 UTC on 14 January 2005 | Titan IVB Centaur-T |
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.| Spacecraft | Launch Date | Operator | Mission | Outcome | Remarks | Carrier rocket |
| Voyager 2 | NASA United States | Flyby | Closest approach at 17:59 UTC on 24 January 1986, later flew past Neptune | Titan IIIE Centaur-D1T |
Neptune
Voyager 2 is also the only spacecraft to have visited Neptune, making a single flyby as part of its grand tour of the outer planets.| Spacecraft | Launch Date | Operator | Mission | Outcome | Remarks | Carrier rocket |
| Voyager 2 | NASA United States | Flyby | Closest approach at 03:26 UTC on 25 August 1989 | Titan IIIE Centaur-D1T |