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. 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 of missions to the outer Solar System

System Spacecraft	Jupiter Jupiter trojans	Saturn	Uranus Uranus trojans	Neptune Neptune trojans	Distant minor planets
Pioneer 10	1973 flyby Jupiter and moons
Pioneer 11	1974 flyby Jupiter and moons	1979 flyby Saturn and moons
Voyager 1	1979 flyby Jupiter and moons	1980 flyby Saturn and moons
Voyager 2	1979 flyby Jupiter and moons	1981 flyby Saturn and moons	1986 flyby Uranus and moons	1989 flyby Neptune and moons
Ulysses	1992, 2004 gravity assist Jupiter
Galileo	1995–2003 orbiter Jupiter and moons 1995 atmospheric Jupiter
Cassini–Huygens	2000 gravity assist Jupiter and moons	2004–2017 orbiter Saturn and moons 2005 lander Titan
New Horizons	2007 gravity assist Jupiter and moons				2015 flyby Pluto and moons 2019 flyby 486958 Arrokoth
Juno	2016–2025 orbiter Jupiter
Lucy	2027– flyby mission (launched 2021) 3548 Eurybates 15094 Polymele 11351 Leucus 21900 Orus 617 Patroclus
Jupiter Icy Moons Explorer	2031– orbiter mission (launched 2023) Jupiter and Ganymede

For proposed and planned future missions see: List of proposed Solar System spacecraft

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).

Timeline
Spacecraft	Launch date	Operator	Mission	Outcome	Remarks	Carrier rocket
Pioneer 10	3 March 1972	NASA United States	Flyby	Successful	Closest approach at 02:25 UTC on 4 December 1973	Atlas SLV-3C Centaur-D
Pioneer 11	6 April 1973	NASA United States	Flyby	Successful	Closest approach at 05:22 UTC on 3 December 1974, later flew past Saturn	Atlas SLV-3D Centaur-D1A
Voyager 2	20 August 1977	NASA United States	Flyby	Successful	Closest approach at 22:29 on 9 July 1979, later flew past Saturn, Uranus and Neptune	Titan IIIE Centaur-D1T
Voyager 1	5 September 1977	NASA United States	Flyby	Successful	Closest approach at 12:05 UTC on 5 March 1979, later flew past Saturn	Titan IIIE Centaur-D1T
Galileo	18 October 1989	NASA United States	Orbiter/Atmospheric	Successful	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.	Space Shuttle Atlantis STS-34 / IUS
Ulysses	6 October 1990	NASA United States / ESA	Gravity assist	Successful	Flyby on 8 February 1992 to reach a high-inclination heliocentric orbit. Also made a distant incidental flyby on 4 February 2004	Space Shuttle Discovery STS-41 / IUS
Cassini–Huygens	15 October 1997	NASA United States / ESA	Gravity assist	Successful	Flyby on 30 December 2000 en route to Saturn	Titan IV(401)B Centaur-T
New Horizons	19 January 2006	NASA United States	Gravity assist Major observation campaign from Jan-June	Successful	Flyby on 28 February 2007 (closest approach at 05:43:40) en route to Pluto	Atlas V 551
Juno	5 August 2011	NASA United States	Orbiter of Jupiter	Operational	Entered orbit 4 July 2016	Atlas V 551
JUICE	14 April 2023	ESA	Orbiter of Jupiter Orbiter of Ganymede	En route		Ariane 5 ECA

Missions whose primary objectives were not related to the exploration of Jupiter are indicated in grey

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.

Timeline
Spacecraft	Launch date	Operator	Mission	Outcome	Remarks	Carrier rocket
Pioneer 11	6 April 1973	NASA United States	Flyby	Successful	Closest approach on 1 September 1979 at 16:31 UTC	Atlas SLV-3D Centaur-D1A
Voyager 2	20 August 1977	NASA United States	Flyby	Successful	Closest approach at 01:21 UTC on 26 August 1981, later flew past Uranus and Neptune	Titan IIIE Centaur-D1T
Voyager 1	5 September 1977	NASA United States	Flyby	Successful	Closest approach on 12 November 1980 at 23:45 UTC	Titan IIIE Centaur-D1T
Cassini	15 October 1997	NASA United States	Orbiter	Successful	Entered orbit 1 July 2004; mission concluded on 15 September 2017	Titan IV(401)B Centaur-T
Huygens	15 October 1997	ESA / ASI Italy	Titan lander	Successful	Deployed from Cassini; landed on Titan at 10:13 UTC on 14 January 2005	Titan IV(401)B 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.

Timeline
Spacecraft	Launch date	Operator	Mission	Outcome	Remarks	Carrier rocket
Voyager 2	20 August 1977	NASA United States	Flyby	Successful	Closest approach at 17:59 UTC on 24 January 1986, later flew past Neptune	Titan IIIE Centaur-D1T

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.

Timeline
Spacecraft	Launch date	Operator	Mission	Outcome	Remarks	Carrier rocket
Voyager 2	20 August 1977	NASA United States	Flyby	Successful	Closest approach at 03:26 UTC on 25 August 1989	Titan IIIE Centaur-D1T

References