Jupiter		Uranus
	Saturn		Neptune

Jupiter, Saturn, Uranus, and Neptune are the gas giants of our solar system.

Jupiter

• Pioneer 10 ( Pioneer-F) (USA)  3 March 1972. Passed 132,250 km from Jupiter on 3 December 1973, collected and returned data. Has now left the solar system. The last successful data acquisition on 27 April 2002. The spacecraft signal was last detected on 23 January 2003.
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• Galileo (USA)  18 October 1989. Atmospheric probe to Jupiter. Passed Venus, passed Earth twice, and encountered three asteroids getting to Jupiter. It arrived at Jupiter in December 1995 and discovered a possible underground ocean on Europa. It was crashed into Jupiter on September 21, 2003, to avoid any possibility of a collision with a Jovian moon.
• Ulysses(International Solar Polar Mission, Solar Polar) (ESA)  6 October 1990. Went by Jupiter (February 1992) so that it could swing around and go into a polar solar orbit. First craft to pass over the poles of the sun (south pole in mid-1994, north pole in mid-1995).

Saturn

• Cassini (USA)  15 October 1997 Currently en route. Carries the Huygens probe to research the atmosphere of Saturn. Due to arrive on July 1, 2004.

Jupiter/Saturn

• Pioneer 11 ( Pioneer-G) (USA)  6 April 1973. Passed 42,900 km from Jupiter on 4 December 1974, and 20,930 from Saturn on 1 September 1979. It collected and returned data. Science operations and daily telemetry ceased on 30 September 1995. It has now left the solar system.
• Voyager 1 ( Mariner Jupiter/Saturn A) (USA)  5 September 1977. Flew by both Jupiter (5 March 1979) and Saturn( 12 November 1980). Some 18,000 images of Jupiter and its satellites were taken by Voyager 1. In addition, roughly 16,000 images of Saturn, its rings and satellites were obtained. Voyager was rechristened the Voyager Interstellar Mission (VIM) in 1989. On 14 February 1990, Voyager 1 looked back and took the first "family portrait" of the solar system, a mosaic of 60 frames of the Sun and six of the planets (Venus, Earth, Jupiter, Saturn, Uranus, and Neptune) as seen from "outside" the solar system. The cameras on Voyager 1 were then once again turned off.

Jupiter/Saturn/Uranus/Neptune

• Voyager 2 ( Mariner Jupiter/Saturn B) (USA)   20 August 1977. Flew by Jupiter (9 July 1979), Saturn (5 August 1981), Uranus (24 January 1986), and Neptune (25 August 1989). All experiments and encounters have returned useful data.