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. Only one spacecraft, Voyager 2, has 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.

Summary

Jupiter Jupiter trojans Saturn Uranus Uranus trojans Neptune Neptune trojans Pluto Trans-Neptunian objects 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 moons2019 flyby 486958 Arrokoth Juno 2016– 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 Europa Clipper 2030– orbiter mission (launched 2024) Europa

Jupiter

Nine 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).NASA Jupiter Press Kit (pdf)

Mission Spacecraft Launch date Carrier rocket Operator Mission Type Outcome 1 Pioneer 10 Pioneer 10 NASA Flyby Humanity's first object to attain Solar system's escape velocity. First probe to traverse the asteroid belt, to reach Jovanian system, to use a gravity assist and to leave the proximity of Solar systems' planets. Held the record for fastest human-made object at the time and the most distant one until Voyager 1 overtook in 1998. Closest approach towards Jupiter was at 02:25 UTC on 4 December 1973. Flew by Callisto, Ganymede, Europa and Io at long distances. Final signal received on 23 January 2003, from Earth. 2 Pioneer 11 Pioneer 11 NASA Flyby Closest approach towards Jupiter at 05:22 UTC on 3 December 1974. Flew by Callisto, Ganymede, Io and Europa . First probe to reach Saturnian system. Final contact was roughly at a distance of 3 Voyager 2 Voyager 2 NASA Flyby Closest approach at 22:29 on 9 July 1979. Flew past Callisto, Ganymede, Europa, Amalthea and Io at long distances. Later flew past Saturn, Uranus and Neptune. Oldest active space probe at . Currently studying interstellar medium. At a distance of from Earth 4 Voyager 1 Voyager 1 NASA Flyby Closest approach at 12:05 UTC on 5 March 1979. Flew past Amalthea, Europa, Ganymede and Callisto at long distances. Later flew past Saturn. First probe to depart heliosphere and enter interstellar medium. Most distant human-made object at a distance of from Earth . 5 Galileo project Galileo NASA Orbiter Atmospheric entry probe Atmospheric probe First probe to enter Jupiter's atmosphere. Entered 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. – Ulysses Ulysses NASA/ESA Flyby Flyby on 8 February 1992 to reach a high-inclination heliocentric orbit. Also made a distant incidental flyby on 4 February 2004 – Cassini NASA/ESA Flyby Huygens lander Flyby on 30 December 2000 en route to Saturn 6 New Horizons New Horizons NASA Flyby Gravity assist. Major observation campaign from Jan-June. Flyby on 28 February 2007 (closest approach at 05:43:40) en route to Pluto. First probe to flyby Plutonian system. 7 Juno Juno NASA Orbiter Entered orbit 4 July 2016. First outer planet explorer probe with solar panels. 8 Jupiter Icy Moons Explorer JUICE ESA Orbiter First interplanetary probe to the outer Solar System planets not launched by the United States and the first set to orbit a moon (Ganymede) other than Earth's Moon.9 Europa Clipper Europa Clipper 14 October 2024 Falcon Heavy NASAOrbiter Jupiter orbiter with Europa flybys

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.

Mission Spacecraft Launch date Carrier rocket Operator Mission Type Outcome 1 Pioneer 11 Pioneer 11 NASA Flyby First probe to reach Saturnian system. Closest approach on 1 September 1979 at 16:31 UTC. Flew past Iapetus, Dione, Mimas, Tethys, Enceladus, Rhea and Titan at long distances. Discovered Epimetheus and Janus. 2 Voyager 2 Voyager 2 NASA Flyby Closest approach at 01:21 UTC on 26 August 1981. Flew past Iapetus, Titan, Dione, Mimas, Enceladus, Tethys and Rhea at long distances. Later flew past Uranus and Neptune. 3 Voyager 1 Voyager 1 NASA Flyby Closest approach on 12 November 1980 at 23:45 UTC. Flew past Titan, Tethys, Mimas, Enceladus and Rhea. 4 Cassini NASA Orbiter Huygens ESA Titan lander Entered orbit 1 July 2004. First probe to orbit Saturn. Discovered seven new moons. Huygens probe became the first spacecraft to land on Titan with the farthest landing from Earth a spacecraft ever made. It was deployed from Cassini and landed at 10:13 UTC on 14 January 2005. Mission concluded on 15 September 2017.

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. Mission Spacecraft Launch date Carrier rocket Operator Mission Type Outcome 1 Voyager 2 Voyager 2 NASA Flyby Discovered eleven moons. Flew past Miranda, Ariel, Umbriel, Titania and Oberon. Closest approach at 17:59 UTC on 24 January 1986. Later flew past Neptune.

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. Mission Spacecraft Launch date Carrier rocket Operator Mission Type Outcome 1 Voyager 2 Voyager 2 NASA Flyby Discovered Neptunian rings and six new moons. Flew past Larissa, Proteus and Triton. Closest approach at 03:26 UTC on 25 August 1989

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). Mission Spacecraft Launch date Carrier rocket Operator Mission Type Outcome 1 New Horizons New Horizons NASA Flyby Flew by Pluto on July 14, 2015, flew past Arrokoth on 1 January 2019.

Statistics Major milestones Legend

† First to achieve + Planets Country/Agency Jupiter Saturn Uranus Neptune Flyby Orbit Atmospheric entry Flyby Orbit Atmospheric entry Flyby Flyby United States Pioneer 10, 1973 † Galileo, 1995 † Atmospheric probe, 1995 † Pioneer 11, 1979 † Cassini, 2004 † Cassini, 2017 † Voyager 2, 1986 † Voyager 2, 1989 † ESA Ulysses, 1992 Juice, TBD 2031 — — — — — —

+ Galilean moons Country/Agency Ganymede Callisto Io Europa Flyby Orbit Impact Flyby Flyby Flyby United States Pioneer 10, 1973 † —Europa Clipper, TBD 2034 † Pioneer 10, 1973 † Pioneer 10, 1973 † Pioneer 10, 1973 † ESA Juice, TBD 2034 Juice, TBD 2034 † Juice, TBD 2035 — — —

+ Major Saturnian moons Country/Agency Titan Rhea Iapetus Dione Tethys Enceladus Mimas Flyby Orbit Lander Flyby Flyby Flyby Flyby Flyby Flyby United States Pioneer 11, 1979 † — — Pioneer 11, 1979 † Pioneer 11, 1979 † Pioneer 11, 1979 † Pioneer 11, 1979 † Pioneer 11, 1979 † Pioneer 11, 1979 † ESA — — Huygens, 2005 † — — — — — —

Future missions Mission Spacecraft Launch date Carrier rocket Operator Planned missions Dragonfly Dragonfly TBD July 2028 Falcon Heavy NASA Titan robotic rotorcraft Tianwen-4 Tianwen-4 TBD September 2029 Long March 5 CNSA Uranus flyby probe Jupiter and Callisto orbiter; Flyby past Uranus with mission extension planned for interstellar journeySolar Polar Orbit ObservatorySolar Polar Orbit ObservatoryNET 2029TBD CNSA Will use a Jupiter gravity assist to reach high-inclination heliocentric orbit ESA Enceladus mission Early 2040s Ariane 6 ESA L4 mission in the ESA Science Programme's Voyage 2050 campaign. Proposed missions IHP-1 Shensuo TBD TBD CNSA Interstellar heliospheric probe with Jovian gravity assist; planned flybys of Jupiter and 50000 Quaoar IHP-2 Shensuo TBD TBD CNSA Interstellar heliospheric probe with Jovian gravity assist; planned flybys of Jupiter, Neptune, Triton and a Kuiper belt object Uranus Orbiter and Probe Uranus orbiter NET 2031 Falcon Heavy (expendable) NASA Uranus probe Uranus orbiter after a flyby of Jupiter; Uranus atmospheric probe Enceladus Orbilander Enceladus Orbilander NET 2038 NASA Enceladus orbiter/lander

See also Timeline of Solar System exploration List of missions to Venus List of missions to the Moon List of missions to Mars List of missions to minor planets List of missions to comets List of extraterrestrial orbiters Interstellar probe List of artificial objects leaving the Solar System List of proposed Solar System probes Kuiper belt (approx. 30–50 AU, Pluto largest of this group) List of proposed missions to the outer planets List of trans-Neptunian objects (numbered, excludes comets, see Trans-Neptunian object)

References