It's been 30 years since NASA's two Voyager spacecraft first visited Saturn, but the legacy of the discovery created by the probes still lingers at the ringed planet today.
Voyager 1 made its closest flyby of Saturn 30 years ago today (Nov. 12) and its sister craft, Voyager 2, followed suit nearly a year later on Aug. 25, 1981. The two probes discovered six previously unknown — and small — moons, offered a glimpse into the dynamics of Saturn's rings and confirmed that Titan, Saturn's largest moon, has a thick, nitrogen-rich atmosphere. [Images: Voyager's Photo Legacy.]
These findings alone opened astronomers' eyes to the richness of the Saturn system. But the Voyager encounters sparked so many new questions that another spacecraft, NASA's Cassini orbiter, was sent to probe those mysteries two decades later, researchers said.
"When I look back, I realize how little we actually knew about the solar system before Voyager," said Ed Stone of Caltech, a project scientist for the Voyager mission back in the day. "We discovered things we didn't know were there to be discovered, time after time."
While the Cassini mission has been a cooperative effort between NASA, Italy and the European Space Agency — which built a Titan lander that rode piggyback on Cassini — the twin Voyager probes launched in 1977 solely as NASA missions are, today, the spacecraft farthest from Earth.
Trailblazers at Saturn
Voyager 1's closest approach to Saturn in 1980 brought the probe to within 78,300 miles (126,000 kilometers) of the planet's cloud tops, and Voyager 2 came within 62,600 miles (100,800 km). The two close encounters — part of a broader "grand tour" of the outer solar system — revealed a Saturn scientists had never seen before. [Top 10 Voyager Probe Facts]
Voyager photos, for example, showed huge storms roiling Saturn's atmosphere — something that Earth-based telescopes hadn't picked up, researchers said. And the spacecraft also discovered strange kinked patterns in Saturn's F ring, discovered only the year before by NASA's Pioneer 11 probe.
The two Voyagers also revealed that the surface of Enceladus, Saturn's sixth-largest moon, was surprisingly young in places, pointing toward recent geological activity.
Scientists used Voyager observations to resolve debates over whether Titan's atmosphere is thick or whisker-thin. The Voyagers found Titan to be shrouded in a thick haze of hydrocarbons in a nitrogen-rich atmosphere, leading scientists to predict that seas of liquid methane and ethane might dot the moon's surface, researchers said.
"It was clear Voyager was showing us something different at Saturn," Stone said. "Over and over, the spacecraft revealed so many unexpected things that it often took days, months and even years to figure them out."