Since their launches nearly 40 years ago, the Voyager missions have changed how we look at our solar system.
In August and September 1977, Voyager 1 and Voyager 2 were launched into space, on a trajectory that would take them to Jupiter, Saturn and beyond.
They discovered Jupiter's ring, the dark spot on Neptune and the volcanoes on Io. In 2012, Voyager 1 became the first human-made craft to enter interstellar space.
Along for the rides on Voyager 1 and Voyager 2 are the famous Golden Records: phonographs with music, greetings and photographs meant to give aliens an introduction to Earth and its inhabitants.
The missions are the subject of a new documentary "The Farthest -- Voyager in Space," which will air on PBS stations at 9 p.m. on Aug. 23.
There was an advance screening of the film at the Franklin Institute in Philadelphia on Aug. 10, complete with a panel featuring Voyager mission scientists Fran Bagenal (Co-Investigator Plasma Science) and Rich Terrile (Imaging Science), as well as Nick Sagan, the son of scientist Carl Sagan. Nick Sagan gave one of the greetings on the Golden Record when he was six years old.
We spoke with Bagenal and Terrile before the screening on Facebook Live. You can watch the full interview in the video below, or just scroll past the video to read highlights.
What is the most interesting thing we've learned from Voyager?
Terrile: "I think the most interesting thing was that the solar system is far more surprising than our imaginations had led us to believe. The eye-opening thing about Voyager is we discovered that the real solar system was more like science fiction than science fact up until that point."
Bagenal: "The moons of the giant planets were all so different. We thought it'd be like our moon, very boring, kind of dull. But no... each one has a character, a special geology, a whole special formation, all sorts of different things we learnt. Everytime we went to a new place it was totally different."
When did you feel like Voyager had been successful?
Terrile: "The very first encounter with Jupiter. We knew the most about Jupiter than any other objects we've been to. We've been there before with other spacecrafts. It's closer so telescopes can see it more clearly. But at Jupiter there were just so many surprises. And as Fran said, the moons were just this incredible variety of places with erupting volcanoes, moons that the geology changes at the same timeframe the weather changes on our planet. That was just so mind blowing. That just set the stage for one incredible encounter after another."
Bagenal: "One of the most exciting images I remember seeing was in the New York Times and it was above the fold and it was a picture of Jupiter with a great red spot with the moons in front. Famous picture and I'll always have it in my mind. Going into the news agents, as they had back then, and looking in and seeing this picture was fantastic."
Pennsylvania guide to the Great American Solar Eclipse August 21
The Great American Solar Eclipse will move across the U.S., from northwest to southeast, on Monday, August 21.
What do you hope is the future of space exploration?
Terrile: "The future was always supposed to be something more exciting than the reality that has happened. I grew up in the '60s at the start of the space program, Apollo. If you extrapolated from what the beginnings of our space program were in 1961... by '69 we got to the moon. We had cars on the moon. We developed rendezvous docking, ability to get into orbit, space suits, all the technology we use today. It's hard to believe we're in 2017 and we don't even have the capability to go into Earth orbit with humans."
Bagenal: "I'm going to disagree with you...there's nothing that humans can do in space that robots can't do better, faster, cheaper and more effectively except tourism. I would argue that the answer is robots and the future is robots. We're going to send a whole batch of robots out there to go to all sorts of places. The next place is Europa where we're going to go look at the ice and we're going to find out whether or not there could possibly be organisms underneath, potentially life-related organisms, and whether or not there's any communication between the ocean that's underneath and the surface. That will be very exciting and we'll send robots to go do it."
Research that could change the world from Philadelphia universities
Researchers at Temple University, Drexel University and University of Pennsylvania are working hard to change the world for the better. Here's how they plan to do it.
It's interesting that you mentioned tourism. I feel like that's a lot of what we hear about today when it comes to new innovations is people wanting to go and tour space and go on luxury trips. Do you feel like that's part of the future then?
Terrile: "One of the things, I worked for Jim Cameron for awhile. And we talk about what makes something dramatic. Clearly a human in space is a dramatic thing. And he put it a little differently, he said what makes it dramatic is when the protagonist is in the picture. What technology allows us to do today is to take those images and the data we get from planetary encounters and not just make that available to one person who is walking on a planetary surface, but make that available to everybody through virtual reality and the kinds of things we're going to see in the next few years.
"We're going to have that absolute visceral experience. Today, at JPL, we can put on these glasses and walk on the surface of Mars, bend down, look at the rocks and even cast shadows and leave footprints. It's an astonishing technology... that's really the future of exploring. Not just one person exploring, but all of us exploring."
Bagenal: "The example I like to give is the Juno mission I'm involved in right now, which is a spacecraft that's in orbit around Jupiter. We have a camera on that spacecraft which is a citizen's science camera. We just took a bunch of pictures of the great red spot a couple weeks ago... all of those pictures are immediately made available to the public and the public takes those pictures, they explore, play with them and then they put them back up and share them... I think this is a new world. It isn't just those of us who are lucky to be professional scientists involved in this, it's everybody."
What is one thing that you hope people learn from "The Farthest -- Voyager in Space?"
Terrile: "For one thing, the breadth and depth and impact that mission had on science, technology and everything else. It's really astonishing. It's been 40 years since we launched Voyager and it's still going and it gave us our first view of the solar system. It changed our perspective. We learned not only how to explore planets but how to explore our own ability to command spacecraft.
"Voyager was made with technology that was basically -- it was 1972 technology that was flown. I don't know if anybody remembers what it was like in 1972, but the magic that we carry around in our pockets -- cell phones -- would have been magic in those days. And computers and everything else have increased in capability in factors of several billions of time. Yet the technology that was frozen in 1972 has provided us with this incredible look."
Bagenal: "The other thing is there was a strong team of people who worked very hard and did a lot of work and were creative and came up with ways to solve problems along the way. There was a lot more human activity needed with the technology, so the teams were quite large and they worked hard together to make this all work."
The Voyager is famous for having the Golden Record. If you could put anything on it, what would you put on it today?
Terrile: "A lot more data. To think about how little data there is on a phonograph record in those days. Very clearly it's hard to condense everything about ourselves and our planet and our society to what could fit on the phonograph."
Pluto, will it ever be a planet again?
Bagenal: "It is a planet! Hey! Dwarf people are people, dwarf planets are planets... actually what was very interesting was it got everybody debating, discussing and thinking what is a planet? Everybody got discussing stuff. Actually, despite the fact I've had big arguments with Mike Brown (the professor whose discovery of Eris led to the demotion of Pluto to dwarf planet status), we're still good friends, it was all good actually because it got people discussing, debating and talking and so on and so forth."
Gallery: Close-up images of Pluto and its moons
Will we ever find evidence of life or the possibility of living organisms on other planets?
Terrile: "I think we will. If we don't find it in our solar system, which I think it is a very very good probability that it exists in our solar system, if we don't, we'll find evidence on other planets. We've found thousands of other planets and we're going to get to the point where we can look for signatures of life."
Bagenal: "It's tough. Looking for life isn't easy. It's not going to be the first mission to Europa (one of Jupiter's moons) that will find it, probably. It may be two or three later down the road. But it's a good chance. Enceladus (the sixth moon of Saturn) is another place, perhaps Titan (another one of Saturn's moons). I think Mars is overrated, personally."
Terrile: "Mars may have had life... and certainly, if Mars had a viable environment. And we know Mars and Earth exchanged material."
Bagenal: "Right. It's probably just slime, nothing very exciting."
Terrile: "A habitable environment early on could have had at least Earth life on it."
Bagenal: "Yeah, but it probably didn't wiggle."
Terrile: "And if life started on Mars, then maybe that life showed up on our planet. Maybe we're Martians. These are the kind of questions that are actually valid in astrobiology."
Bagenal: "It is true. The exchange of material between the planets, we're just beginning to explore the possibilities and ideas."
Are we no longer alone? NASA finds habitable planets outside solar system
The exoplanet system TRAPPIST-1 is about 40 light years (235 trillion miles) from Earth
Do you feel the fact we've haven't gone to space in a while is a challenge for the next generation?
Bagenal: "We have via robots. I see people excited by seeing what's happening on all the many robots we have on many planets around our solar system and what we're seeing with telescopes out further and beyond. I think what's exciting about the next generation is to go look at all these other places we've not been to yet and to use these robotic explorers to develop and find out more about these places.
"It's a challenge, because the technology is difficult and you have to make it work -- but it's a good challenge."
Terrile: "I also think we're seeing an erosion of science where people try to politicize it for their own needs, with things like climate change. They'll say 'oh those scientists, they have their own agenda. They're like the pharmaceutical industry or these other groups' but we're not. We're out to find the truth. We're out to explore. And whatever answer comes out, that's the answer. That's the truth. We're very careful about that. When the truth hurts, when the truth is not something that is politically viable, I'm afraid that people cash out on us for that."
