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The remarkable engineering triumph of the Voyager program

Artist rendition of the Voyager spacecraft against a background of stars

In 1977, two spacecraft, Voyager 1 and 2, were launched on their mission from Cape Canaveral to explore Jupiter and Saturn. Not only did they accomplish those missions, but they also continued on to observe Uranus and Neptune, eventually reaching interstellar space, where they continue to operate and send back valuable information to scientists today. On this edition of "Weekend Insight," TPR's Jerry Clayton talks about this remarkable feat of engineering with Voyager project scientist Linda Spilker.

This conversation has been edited for length and clarity.

Clayton: Give us a quick overview of the Voyager project that started going on 47 years ago now.

Spilker: The two Voyager spacecraft launched in 1977, and their original mission was to visit the four outer planets Jupiter, Saturn, Uranus and Neptune, which Voyager 2 did, visiting all four planets. And then after that, continue to study the heliosphere. That's the bubble created by our sun crossing the heliopause. Voyager 1 crossed in 2012. Voyager 2 crossed the heliopause in 2018.

Clayton: Now, Voyager 1 is now the farthest manmade object away from Earth. Is that correct?

Spilker: That's right. Jerry. Voyager 1 is now about 15 billion miles away from the sun, and it's traveling about a million miles per day. So, getting farther away every day and it won't be coming back. It's going to continue in that space between the stars.

Clayton: That distance is mind-boggling. And what's more mind-boggling is that you're able to communicate back and forth with the spacecraft. Now, I know there have been a few communications issues over the years, but back in November of 2023, tell me what happened with Voyager 1? Did you guys think it was over with?

Spilker: Well, Voyager 1 went from one day sending back good science and engineering data until the next day just sending back a single tone, essentially like a dial tone from a phone. And there was no longer any information. And so, we were really worried that we had no information coming from the spacecraft, except we knew it was still there. And so, then the task began to figure out what had happened to Voyager 1.

Clayton: And how did you fix that problem?

Spilker: We tried a series of steps and finally identified that a chip in the flight data subsystem memory had failed, and it was stuck at a bit. And so, it was no longer working the way that it should. So we figured out we needed to move all of the computer programing the subroutines to a good portion of the memory, and then link it all back together and get it to run. And that's exactly what we did.

Clayton: How simple are these systems on board the spacecraft computer-wise compared to technology today?

Spilker: Oh, the Voyager computers are much simpler than the technology we have today. In fact, the total memory of the Voyager computers is about equivalent to what you have on your key fob. So, your cell phone is much more capable than the Voyager computers.

Clayton: So what's next for Voyager 1 and Voyager 2?

Spilker: Well, both Voyagers are going to continue to explore interstellar space. We think that they'll last it, barring any other anomalies out until about the 2030s, at which point the power will be too low to maintain operation of the spacecraft. Each of them carries a golden record, with the sights and sounds of the Earth moving out toward stars in the future. And so they'll become our silent ambassadors, carrying our message of hope and goodwill to the rest of the universe.

Is there a topic or person you'd like to hear featured on this program? Email us at weekendinsight@tpr.org

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Jerry Clayton can be reached at jerry@tpr.org or on Twitter at @jerryclayton.