Voyager 1 & 2
Grand-tour probes of the giant planets and heliosphere.
Overview
Launched in 1977, the twin Voyager probes exploited a rare planetary alignment to tour Jupiter, Saturn, Uranus and Neptune. Both spacecraft have now crossed into interstellar space, still returning data about the heliosphere's boundary.
Key discoveries
- Active volcanism on Io
- Jupiter's faint ring and lightning
- First close-ups of Uranus and Neptune and their moons
- First spacecraft to cross into interstellar space