<P> 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 . </P> <P> 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 . </P> <P> Six spacecraft have been launched to explore Jupiter, with an additional three spacecraft making gravity - assist flybys without the exploration of Jupiter being one of their primary objectivess . </P> <Table> Timeline <Tr> <Th> Spacecraft </Th> <Th> Launch Date </Th> <Th> Operator </Th> <Th> Mission </Th> <Th> Outcome </Th> <Th> Remarks </Th> <Th> Carrier rocket </Th> </Tr> <Tr> <Td> Pioneer 10 </Td> <Td> 000000001972 - 03 - 03 - 0000 3 March 1972 </Td> <Td> NASA United States </Td> <Td> Flyby </Td> <Td> 4Successful </Td> <Td> Closest approach at 02: 25 UTC on 4 December 1973 </Td> <Td> Atlas SLV - 3C Centaur - D </Td> </Tr> <Tr> <Td> Pioneer 11 </Td> <Td> 000000001973 - 04 - 06 - 0000 6 April 1973 </Td> <Td> NASA United States </Td> <Td> Flyby </Td> <Td> 4Successful </Td> <Td> Closest approach at 05: 22 UTC on 3 December 1974, later flew past Saturn </Td> <Td> Atlas SLV - 3D Centaur - D1A </Td> </Tr> <Tr> <Td> Voyager 2 </Td> <Td> 000000001977 - 08 - 20 - 0000 20 August 1977 </Td> <Td> NASA United States </Td> <Td> Flyby </Td> <Td> 4Successful </Td> <Td> Closest approach at 22: 29 on 9 July 1979, later flew past Saturn, Uranus and Neptune </Td> <Td> Titan IIIE Centaur - D1T </Td> </Tr> <Tr> <Td> Voyager 1 </Td> <Td> 000000001977 - 09 - 05 - 0000 5 September 1977 </Td> <Td> NASA United States </Td> <Td> Flyby </Td> <Td> 4Successful </Td> <Td> Closest approach at 12: 05 UTC on 5 March 1979, later flew past Saturn </Td> <Td> Titan IIIE Centaur - D1T </Td> </Tr> <Tr> <Td> Galileo </Td> <Td> 000000001989 - 10 - 18 - 0000 18 October 1989 </Td> <Td> NASA United States </Td> <Td> Orbiter / Atmospheric </Td> <Td> 4Successful </Td> <Td> 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 . </Td> <Td> Space Shuttle Atlantis STS - 34 / IUS </Td> </Tr> <Tr> <Td> Ulysses </Td> <Td> 000000001990 - 10 - 06 - 0000 6 October 1990 </Td> <Td> NASA United States / ESA </Td> <Td> Gravity assist </Td> <Td> N / A </Td> <Td> Flyby on 8 February 1992 to reach a high - inclination heliocentric orbit . Also made a distant incidental flyby on 4 February 2004 </Td> <Td> Space Shuttle Discovery STS - 41 / IUS </Td> </Tr> <Tr> <Td> Cassini--Huygens </Td> <Td> 000000001997 - 10 - 15 - 0000 15 October 1997 </Td> <Td> NASA United States / ESA </Td> <Td> Gravity assist </Td> <Td> N / A </Td> <Td> Flyby on 30 December 2000 en route to Saturn </Td> <Td> Titan IV (401) B Centaur - T </Td> </Tr> <Tr> <Td> New Horizons </Td> <Td> 000000002006 - 01 - 19 - 0000 19 January 2006 </Td> <Td> NASA United States </Td> <Td> Gravity assist </Td> <Td> N / A </Td> <Td> Flyby on 28 February 2007 (closest approach at 05: 43: 40) en route to Pluto </Td> <Td> Atlas V 551 </Td> </Tr> <Tr> <Td> Juno </Td> <Td> 000000002011 - 08 - 05 - 0000 5 August 2011 </Td> <Td> NASA United States </Td> <Td> Orbiter </Td> <Td> 5Operational </Td> <Td> Entered orbit 4 July 2016 </Td> <Td> Atlas V 551 </Td> </Tr> </Table>

What was the first planet to be visited by a spacecraft