When NASA launched Voyager 1 and Voyager 2 in the summer of 1977, its engineers were sending the spacecraft on specific missions. Originally, the space agency tasked the Voyagers with conducting close-up studies of Jupiter and Saturn. They would compile data on magnetic fields, the Sun’s influence, Saturn’s rings, a few large moons, and send back lots of great images. To accomplish all this, engineers built into them a generous (for the 1970s) five-year lifetime.
At Jupiter, and then Saturn, the mission achieved far more than its original objectives. Then came the big news: By carefully tweaking Voyager 2’s flight path, flybys of Uranus and Neptune were possible.
The two-planet addition became the Grand Tour. The projected lifetimes stretched to 12 years for the Neptune encounter August 24, 1989. And that date would, in turn, become early history. As of 2018, both Voyagers have finished their fourth decade of operation — and they show no signs of stopping.
