Sat. Feb 4th, 2023

Sunday marks the 40th anniversary of Voyager 2’s launch, which confused the press and public at the time because it actually launched before Voyager 1. Why did they launch the second probe first? Because Voyager 2 would take a longer trajectory to reach the Jupiter system, allowing it to fly past Saturn, Uranus, and Neptune. Voyager 1 launched 16 days later on a faster orbit optimized to fly past Jupiter and Saturn and pass Saturn’s intriguing moon Titan relatively close by.

The missions were, of course, great successes. Voyager 1 reached Jupiter on March 5, 1979, about four months before its twin. Scientists weren’t sure what they would find there. Pioneer 10 and 11 had given them some insight about Jupiter and Saturn as gas giants, but little information was known about the many moons of these worlds. Most scientists thought they would probably look a lot like the cold, dark, and lifeless moons of Earth and Mars.

They were anything but. If you talk to the scientists involved with the Voyagers and ask when they knew their missions would reveal something very different and truly alien, they point to the discovery of volcanic activity on Jupiter’s moon Io. Until then, the only known active volcanoes in the solar system were on Earth. Here was a small moon with 10 times the volcanic activity.

“That was really the wake-up call for a journey that was even more spectacular in terms of what we were going to discover than we could imagine,” said Ed Stone, who has been Voyager’s chief scientist since the program. began in 1972. “There were many of them. That’s really the beauty of Voyager. But if I had to pick one that was symbolic, it would be Io.”

Io really was the start of a special journey. After that, the Voyager spacecraft found a deep-sea ocean on Europa, methane seas on Titan, and likely geysers on Triton. Later, Voyager 1 took an iconic photo of Earth among the other planets in the solar system. Later, it completely left the system in the void of interstellar space.

“Over and over again, we discovered things that we hadn’t even imagined,” Stone told Ars. Indeed. We still marvel today.

List image by NASA

By akfire1

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