30th Anniversary of The Planetary Society

Space Topics: Neptune

Missions to Neptune

Only one mission has visited Neptune.


Voyager 2
“Grand Tour” flybys of Jupiter, Saturn, Uranus, and Neptune
Launch: August 20, 1977
Neptune encounter: June 5 through October 2, 1989

Voyager 2 flew by Neptune on August 25, 1989. Since Neptune was the final target for the spacecraft, scientists decided they could take risks they had avoided during previous planetary encounters. They programmed Voyager 2 to fly within 5,000 kilometers (3,105 miles) of the planet's cloud tops, closer than it had come to Jupiter, Saturn, or Uranus. The results were impressive. Even at such a great distance from the Sun, the 4-hour time lag in communications and low lighting conditions, the spacecraft returned 10,000 images of Neptune, its moons, and ring system. Voyager 2 discovered interesting cloud features on the planet and recorded some of the fastest winds in the solar system. The spacecraft also discovered the clumpiness of Neptune’s rings, as well as six new moons.  The close approach to Neptune actually slowed Voyager 2’s speed with respect to the Sun, and sent the spacecraft on a trajectory diving below the plane of the solar system.