The two Voyager spacecraft launched in 1977 are now the farthest man-made objects from Earth, at more than 19.5 billion and 16 billion kilometers away, respectively. In 2012 Voyager 1 became the first spacecraft to leave the solar system and enter interstellar space—and its sister spacecraft is not far behind.
Both probes were the first to visit the solar system’s giants, Jupiter and Saturn, and Voyager 2 flew by the other outer planets; they changed our understanding of those worlds profoundly. The Voyagers also carry “golden records” packed with recordings of sounds, songs and pictures to communicate a sense of life on Earth to any extraterrestrials that might encounter them.
Arizona State University planetary scientist Jim Bell recounts the story of the Voyagers in his new book The Interstellar Age: Inside the Forty-Year Voyager Mission (Dutton, 2015). Bell spoke to about the impact of the spacecraft and how scientists decided what human facts and achievements to put on the golden records.
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These days we’ve become almost jaded about sending spacecraft to the solar system, but what was the mood among the scientists when they were getting ready to launch the Voyagers?
When the Voyagers reached the outer planets, what effect did their images and data have?
And then for the giant planets themselves, the real revelation was that there are two kinds of giant planets in our solar system, and it turns out now in other systems as well. There are the large gas giants, and then the Uranuses and Neptunes, which are smaller, dominated by volatiles—a different kind of beast. We didn’t know that at the time.
How long can the Voyagers keep running?
There’s nothing to photograph out there. But the squiggly-line science—the fields and particles, cosmic rays—those instruments are lower power, simple to operate. It’s conceivable that it could easily be another decade of having these outposts of human civilization out there.
As they continue on into interstellar space, what will they encounter?
In the absence of sun or wind or anything that’s going to wear them down they could easily outlast us—our entire civilization, outlast our planet. The Earth will eventually be swallowed by the sun and the Voyagers could still be out there. That’s what’s so exciting about having the golden records on them.
How did the golden records come about?
They made a conscious effort to be positive and uplifting, to show pictures and music and readings that were the best part of humanity. They debated a little bit about whether to talk about war, to include a mushroom cloud, and Sagan was very adamant that these represent some of the best parts of humanity. We don’t want it to be seen as threatening. I agree with that philosophy. Science and technology are the best parts of us.
And you put a message in a bottle not for the person on the other side but you do it for yourself, reminding ourselves how far we’ve come as a species and the amazing things we can do for good and for knowledge. It’s a good thing for all of us.
Did anyone think aliens would actually ever find these?
I speculate that it’s really going to be us that finds them—as our technology advances, as we travel out into the solar system and the universe we could easily catch up to the Voyagers and it will be us who reads these.
How active is the Voyager science team today?
I make the point in the book that there’s this misconception among the general public that there are these robots exploring the solar system. But it’s really human exploration, because it’s people controlling these machines, people who wish they were there instead of the machine and who try to experience the place, visually and through chemical instruments, as much as possible. So really Voyager is a voyage of human exploration.
Chomsky: We Are All – Fill in the Blank.
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