Sign up for the free Nautilus newsletter: science and culture for people who love beautiful writing. When the two Voyager probes launched into space in 1977, they were headed to uncharted territory. It was the first time humanity had sent robot spacecraft to study up close the four giant outer planets of our solar system: Jupiter, Saturn, Uranus, and Neptune. Stunning images and scientific data captured by the probes over the next few decades altered our understanding of the cosmos. Through the ...