Voyager 1 and Voyager 2 are twin spacecraft, both launched in 1977 on flyby missions to gather data about planets in the outer solar system. Originally planned as five-year missions, both spacecraft are still active more than 30 years later, exceeding expectations and adding significantly to our knowledge of the solar system and beyond.
(Voyager 1) September 5, 1977; (Voyager 2) August 20, 1977
(Voyager 1) November 12, 1980; (Voyager 2) August 25, 1981
End of Mission
Still operating as of 2017, expected to operate until 2025
Conduct close-up studies of Jupiter and Saturn, Saturn's rings, and the larger moons of the two planets.
Measured winds at high speeds in Saturn—500 meters a second (1,100 miles an hour) near the equator. Detected auroras.
Both Voyagers found that Saturn’s atmosphere is almost entirely hydrogen and helium—about 7% of the volume of Saturn’s upper atmosphere is helium (compared with 11% of Jupiter’s atmosphere), while almost all the rest is hydrogen. It was expected that Saturn’s helium content would be the same as Jupiter’s and the Sun’s. The lower abundance of helium in the upper atmosphere of Saturn may imply that the heavier helium is slowly sinking through Saturn’s hydrogen. That might also explain the excess heat that Saturn radiates, more than the energy it receives from the Sun. Saturn is the only planet less dense than water. In the unlikely event that a large enough lake could be found, Saturn would float in it.
Both Voyagers 1 and 2 continue to send back data, providing scientists with valuable observations of the solar system’s edge and interstellar space. Voyager 1 is now the furthest human-made object from the Sun, having surpassed Pioneer 10 on February 17, 1998. On June 28, 2010, Voyager 2 completed 12,000 days of continuous operation.