Voyager Project Manager Suzanne Dodd discusses NASA’s longest-operating mission and the only spacecraft to explore interstellar space.

Suzanne Dodd: I get fan mail for this mission. People send me letters and tell me how much they love Voyager, how much they love the idea that the gold record is out there traveling through space.

Voyager was originally a four-year mission. And we’ve been flying for 45 years.

It’s not flying by planets anymore, but it’s really making astounding discoveries.

Deana Nunley (Host): Welcome back to Small Steps, Giant Leaps, a NASA APPEL Knowledge Services podcast where we tap into project experiences to share best practices, lessons learned and novel ideas.

I’m Deana Nunley.

Voyager is NASA’s longest-operating mission, spanning decades of historic discoveries and firsts. And the twin Voyager probes are the only spacecraft ever to explore interstellar space.

Our guest today is Voyager Project Manager Suzanne Dodd. Suzanne, thank you for joining us.

Dodd: Yeah. Thank you for having me. I’m looking forward to it.

Host: What would you say are the greatest achievements of the Voyager Interstellar Mission?

Dodd: Well, Voyager in itself is just a remarkable mission. We just had our 45th launch anniversary in August. I made a joke once, I said, ‘It’s incredible that a mission can last 45 years. When you think about just your clock radio at your house, how many people have a 45-year-old clock radio?’

So many years of discovery with Voyager and crossing the heliopause back in 2012 with Voyager 1 and now having a 10-year record of interstellar space, the closest — what we call the very local interstellar space closest to our Sun — and a record of how that changes as we go further and further away from the Earth and the Sun. It’s very, very extremely unique data and data that’s not going to be collected for many, many, many decades. I would say another mission isn’t going to get out to where Voyager is for about another 50 years or so.

And every year that we get another year’s worth of data, we are able to disprove a lot of models and create new models about our Sun’s interaction with the interstellar media and how the magnetic field and the charge particles of the space beyond our solar system behaves.

Host: What has it taken to keep Voyager on this incredible journey for more than 45 years?

Dodd: Well, I think it’s a combination of a lot of things. I think first, it was a vision by the people that developed the project. Voyager was originally a four-year mission. NASA requirements were a flyby of Jupiter and a flyby of Saturn. That was the first four years of the mission. And we’ve been flying for 45 years. We were extended to go past Uranus in 1986 and then Neptune in 1989. That ended the planetary part of the mission where we covered all the giant outer planets, but we’ve been traveling toward the heliopause and now in interstellar space for another 30-plus years.

And there was a vision by the people that developed the spacecraft to have it reach past the planets and as far as we could out into the solar system. And so, that’s one piece of it.

Of course, the other piece of it is just building an extremely robust spacecraft from a hardware sense. Voyager had a lot of first technologies onboard. It had radiation-hardened parts so that it could do these planetary encounters without damaging the spacecraft. It had fault protection because it was going so far away from the Earth. It had to be autonomous, and if something went wrong, it needed to put itself in a safe state and be able to contact the Earth. So that use of fault protection, which is now standard through all missions, first started on Voyager. And sort of the idea of also having two spacecrafts, so you have some redundancy in your mission because you have two spacecrafts. That’s not done anymore, just primarily due to cost more than anything else.

And then I think it takes a dedicated group of engineers to fly the mission. And the people that are on the mission now, the majority of them have been on the mission for more than 30 years. They’ve spent decades, they’ve spent their whole career working on Voyager and they’re way past retirement age. They love the mission. They have all the knowledge of what the idiosyncrasies are of the spacecraft. So, it’s a combination of all those things. The vision that the spacecraft could go out past Neptune and beyond, an excellent engineering design, and then a dedicated set of engineers to fly the mission.

Host: What have been the primary challenges?

Dodd: Well, the challenges are kind of normal for most spacecraft, with the exception that for where Voyagers are now. We are extremely far from the Earth, 15 billion miles from the Earth. I’ll give you one perspective: that’s five times as far as Neptune is from the Earth.

Our roundtrip light time, which is the time it takes for us to send a command to the spacecraft, and then for the spacecraft to respond back to us is nearly two days. It’s on the order of 43 hours now. And so communicating with the spacecraft takes a long time. If you’re communicating with the Moon, it’s three seconds. If you’re communicating with the Mars, it’s 20 minutes. When you communicate to Voyager, the one-way light time is 22 hours and roundtrip is 43 hours, 44 hours. So, the spacecraft itself has to be very autonomous because we can’t communicate with it quickly. The data rates are very, very small, 160 bits per second — that’s just tiny. And it takes all the large antennas on the ground of the Deep Space Network arrayed together to get the data back. So the biggest challenge currently for Voyager is really the communications and just the distance and the lack of quick turnaround that we can do with the spacecraft.

But certainly, over the 45 years of the mission there’s been many challenges. And for the planetary encounters, a lot of the challenges related to Uranus and Neptune because they’re much further out than Jupiter and Saturn, which was the prime mission. And the light that the Sun provides at those distant planets is much, much less. So, there were special image processing techniques designed in order to be able to take pictures of Uranus and Neptune.

One example of that is we tracked Neptune by essentially moving the camera to compensate for the rate of the spacecraft so we could get a clear picture. You can imagine taking a picture out your car window and having the distance smeared. That same thing would happen at Neptune, but we designed a software fix that would track the object that you wanted to take an image of so that it reduced the smear of the picture.

So that’s just a couple examples. But certainly, currently, the further we get away from Earth, the distance and the data rate is our biggest challenge to keeping it operating.

Host: And you mentioned that some of the people have been working on this project for 30 years plus. How would you describe the team’s ability to learn and adapt across the decades?

Dodd: Yeah, I think they have adapted. It’s kind of fun to watch people even like myself who left the project after Neptune and then came back to work on it and realized, wow, what a great mission Voyager is. And yes, it’s not flying by planets anymore, but it’s really making astounding discoveries related to our Sun and the heliosphere, and how our whole solar system evolved. So, the people have adapted to the challenges.

It’s a very close team. They all support one another and they’re all very dedicated to the mission. So, if there’s ever a problem, we dig right into it. We look through old documentation. We call in retirees to help us. We’ve got a great Rolodex of people that have left the JPL and retired that we can call on who are on the project early in the mission. So, I think it’s this feeling of being a family and wanting to together solve the issues. And I think that’s what’s helped us, is the family feeling of it. Everybody pitches in to solve any issues that there might be.

Host: That’s so interesting, this whole family feeling. Are there problem-solving approaches in addition to that, that are used by the Voyager team that you might recommend to other project managers?

Dodd: Well, I would recommend that project managers keep track of where people go once they leave your project. If you have a short mission, like a two-year mission, that’s not necessarily the case. But certainly for anything that’s going to go five or 10 years or more, people leave the project and it’s important that you have some type of knowledge capture mechanism. So whether it’s documenting procedures or training videos or something like that so when new people come and join, they understand the processes. And particularly for missions that are going to go, say a decade or longer, you’re going to have a changeover in personnel. So you’re going to have to be able to transfer knowledge from the design engineers to the operators to the second generation of operators. That I think is one of the key aspects for any kind of long-duration mission.

Host: What do you think are among the most valuable lessons learned from Voyager?

Dodd: I think there’s many of them. I think some of the lessons we’ve learned from Voyager and some of the ones that I take away as the most personal is sharing the mission, the highs and the lows and the discoveries with the general public. That’s important. And that shouldn’t be underestimated with regard to how it makes you as a team member feel being involved as this project, but also how it makes NASA and the world feel.

Now, Voyager was very lucky in some regards that Carl Sagan got this idea of putting a gold record on Voyager, knowing that the spacecraft was not a return mission, and it was not a mission that was going to crash into a planet either, right? It’s going to go out there in interstellar space and circle around the center of our galaxy for millions of years.

And this idea of capturing a snapshot of the Earth, of the people and the sounds of what’s on Earth for another potential being to discover in the future, I think that gives a real humanity aspect to the mission. And people around the world have really jumped on board with that. I think even if you don’t know anything about the science of Voyager, you know there’s a gold record on it. And you know that that gold record is a time capsule of us on Earth for other beings to find in the future. And so that, I think, is really one of the true blessings of Voyager, and I certainly hope that any other mission that goes on its way out can do something similar.

Host: Suzanne, let’s talk about the people behind Voyager’s success. Who are a few that stand out to you?

Dodd: Well, certainly I think the most important person is Ed Stone. He just retired after 50 years of being the project scientist. He started five years before the mission was launched in 1972 when the first science steering committee team meeting was held, and he shepherded that mission through each of the planetary encounters on out for the decades of travel ‘til we got to the heliopause, and now 10 years into interstellar space. He was the vision.

It’s not always easy to deal with a group of scientists. They all want to go their own direction. We frequently call it herding cats. That’s what the engineers say about the scientists. The scientists might have their own comments about engineers, but Ed was able to get a consensus, I would say, amongst the science teams about what needed to be done at each encounter and which science was the most important. And to get the scientists to work together to not just think about what was the science for their instrument, but what’s the collective overall science that’s most important to get from that planet. It’s not just the magnetic field, but it’s the magnetic field along with the particle data and the direction of the particle data. That right there is three different instruments.

And he had just a great mannerism about him, and he was an inspiration to all of us that worked on the project, and I think he was always a very gracious man as well. And so, I think his demeanor was truly a role model for what a project scientist should be.

Now, from the engineering side, I would think that Chris Jones was instrumental in the Voyager mission. He started on Voyager about the same time as Ed Stone. He was specific to one area, the Attitude Control System. And he was a younger, well, I would say a younger engineer at launch time. Another person probably in his thirties when launch happened. He went off to do a number of different management roles at JPL, but he always kept track of Voyager. Voyager was his first love. He retired about 10 years ago, but would work with the project even after his retirement. And he was a great mentor to the engineers on the mission, definitely had a huge amount of knowledge on the spacecraft and what the spacecraft could do and how we might be able to modify things to keep it operating longer. And I think, again, he is an inspiration to the people working on the project for his dedication and for his knowledge of what the Voyager spacecraft is capable of doing.

Host: What are some of your favorite moments supporting Voyager missions?

Dodd: Well, in the good old days, reporters had to come to JPL to kind of get the scoop. There weren’t Zoom meetings or that type of electronic communications as much as there is today. And I can very distinctly remember the excitement around the Neptune encounter. It was the last planetary flyby, and for all purposes, it was pretty much the last piece of Voyager. I don’t think a lot of people thought about what would happen to Voyager after it flew by Neptune.

But we had a super large crowd of reporters that came to JPL leading up to the Neptune encounter. There was a lot of buzz and energy at JPL, as you saw the reporters, the CBS Nightly News reporters and others that you were familiar with, walking around and interviewing people. And the project was set up so that they had daily press conferences in the morning so that they could make the press deadlines. But this went on for about two weeks. A week ahead of the closest approach and a week after the closest approach.

So, it just, I think, really gave me the bug for space exploration. There was such a great vibe at JPL around the encounter and having all the press here. It’s a special moment for me. I really remember that, and I think that really set me on the course of, I want to do this space exploration and that’s what I want to do for my career.

Host: Those sound like such good times and fond memories. What can we expect as Voyager continues its mission?

Dodd: Well, I mentioned earlier the fact that we have a very long round-trip light time and very low data rates. But the limiting resource to the mission is really the power. We use radio isotope thermoelectric generators — it’s a fancy way to say nuclear power — that powers the computers on the spacecraft. And we lose four watts of power a year. So, we’ve had to, in just the last few years, actually turn off instrument heaters. And surprisingly, much to our good fortune, the instruments continue to work, even though they’re much colder, 50 degrees Celsius colder than they were when their heaters were on.

The heaters average anywhere from four to six watts of power. So, if we can turn off a heater at four watts, that gains us another year of operating lifetime. So we’re currently now looking at what we can do with spacecraft systems to eke out another six months or a year, another two or four watts to continue this mission and continue the science data taking part of this mission as long as possible because that record of how the space that Voyager is traveling through as it gets further and further from the Sun is very unique, and again, will not be duplicated for decades.

Host: So fascinating. Thank you so much, Suzanne, for joining us today on the podcast. This has been great.

Dodd: Thank you very much. I’ve had fun.

Host: You have any closing thoughts?

Dodd: I truly love this mission, and I love it for a lot of reasons. It was the mission I started on out of college. I was very fortunate to be able to come back on the mission in 2010 as the project manager. And what’s special to me about it, and one of the things that’s special to me about it is, I get fan mail for this mission. People send me letters and tell me how much they love Voyager, how much they love the idea that the gold record is out there traveling through space. I get mail from children who send me pictures of the Voyager 3 spacecraft they have designed. I get mail from retirees who tell me that this is the most exciting mission that they’ve had. And I meet people who got into the space business because of Voyager. And that’s really neat too, to leave that legacy and to promote the next generation of space explorers and know that they got interested in their careers due to the Voyager mission. I think that’s real special.

Host: Suzanne’s bio and links to related resources, including APPEL courses, are available on our website at APPEL.NASA.gov/podcast along with a show transcript.

If you’d like to hear more about historic missions such as Voyager, new missions such as Artemis 1, and everything in between, we encourage you to check out other NASA podcasts at nasa.gov/podcasts.

As always, thanks for listening to Small Steps, Giant Leaps.