Note: This interview was conducted on September 16th, 2020. Some passages have been paraphrased to improve legibility.  

Maci Harrell: What first got you interested in studying planetary geology? 

Ellen Stofan, PhD: So, I obviously have an incredibly weird story. My dad worked for NASA and my mom was a science teacher, but neither of those were what got me interested; frankly, everybody who worked at NASA looked like my dad, and they were all engineers.  

But I knew I wanted to be some kind of scientist, and when my mom was getting a Master’s degree in education when I was about 10 or 11, she took a geology course and asked the professor if I could come along on the field trip because I liked picking up rocks all the time. And so we were going down the streambed in Ohio with these rock walls, and he was explaining how you could understand the last 200 million years of history from looking at these rock walls. I was like, “Wow. I want to be a geologist. I didn’t know you could get paid for picking up rocks.”  

Then when I was 14, still on my geology track, my dad was responsible for launching the first two landers on Mars: the Viking landers. And they put on a program for the families that were down at Cape Canaveral. They had the scientists from the mission talking about why they were studying the geology of Mars and the search for life on Mars, and one of them was Carl Sagan.  And I was like, “Wow, I didn’t know that was a thing.” Even though my dad was involved in it, I hadn’t really focused on it. And so at age 14 I decided I wanted to be a planetary geologist, and that was what I did.  

What’s been your experience working as a woman in such a heavily male-dominated field?  

You know, I feel like I was really lucky because my parents hugely supported me. Teachers really supported me. When I went to William & Mary, I came in and I was like, “I’m going to get a PhD in planetary geology!” and they were like, “Great! How can we help you?” Just incredibly supportive. They were all male professors, but they went out of their way to support me.  

So it really wasn’t until I got to graduate school and then into my professional career where people treated me as something other. And I became really conscious of the fact that often I was the only woman in the room. And by that point, I feel like I had this base of confidence that allowed me to kind of maneuver my way through it. But so many women never have that. They don’t have a supportive family network, or they don’t have supportive teachers, or they have professors who will openly question why they’re there.  

That to me is so frustrating, because I think if I’d encountered that, I would not have continued. I don’t think I would have had that ability to say, “Forget it. I’m going to do this anyway.” And so I really value the fact that I was supported. But then, really, I think it’s the responsibility of all of us to make sure we’re holding up women everywhere, to make sure they know they belong.  

What advice would you give women hoping to go into planetary geology today?  

To me it’s a hugely kept secret that we have the best field in the world, you know? You’re an armchair explorer. I was just talking to someone today about what it felt like when the first Magellan data started coming back, which was the first mission that I had really worked on. 

And you know, you’re sitting in your office, and you’re looking at this image, and you realize you’re one of the first people that’s ever looked at this place on another world. How amazing is it that we get to explore the solar system - and soon, planets beyond the solar system - from our desks? That’s an incredibly fun experience. I think that challenge, that problem-solving, is something that’s really fun.  

And I also try to couch it in these terms: as planetary geologists, what we’re trying to do is understand how planets work. So to me, it always comes back to how do we better understand Earth? Why is Earth such a unique home for life in our solar system? How did the Earth get the way it is? How can we better understand volcanism, tectonics, to help us better understand the forces that can be deadly on this planet?  

And by putting our planet in context with the planets of our solar system, and as we develop better and better technologies, it is amazing to think that someone who’s a planetary geologist 20 years from now is not just going to have the nine - then eight - planets I had to study, but hundreds of planets! We’re learning so much more every day. 

What advice would you give students that want to intern at NASA or at the Smithsonian?  

Apply, first of all. I think a lot of people don’t realize the opportunities are out there. There are opportunities to be a paid intern at NASA and at the Smithsonian Museums. Certainly at Air and Space we pay all our interns. And that’s important, because we need to make sure that everyone has the ability to do a summer job, like an internship, that helps them along in their career, helps them build up their resume. If you’re in a financial position where you’re like, “Well, I have to work. I need something that pays a salary in the summer,” you say, “Well, I can’t go do an unpaid internship.” So it’s really important to me that we pay our interns.  

And then when you look at someone and ask, “Is this person suited?” one of the things to me is are they expressing a passion for this? Why do they want to come to this place? Do they really care?  

And, obviously, work hard in school. But the one thing that frustrates me – I mean, I rarely got better than a B in math, and I often got C’s in math. So even though you might struggle in one of the scientific subjects, don’t give up. Because it really matters that you’re passionate, it matters that you stick to it, it matters that you maybe have to work extra hard in some of those classes.  But don’t think you have to be the valedictorian, the straight A student in order to get opportunities. You don’t. 

I have to say that makes me feel better, because I am awful at math.   

I got a C in a graduate school math class, and my advisor called me in and he was like, “I’m really concerned that you got a C in this class,” and I started laughing. I said, “I thought I was going to fail! I was thrilled with this C!” And he did not like that answer! Just being honest here, buddy. I thought I was going to fail.  

What path would you recommend a student that’s interested in planetary geology take in order to be successful in the field?  

You know, I’d really say avail yourself of internship opportunities. I think that’s really important. 

And a second thing that’s really important to me - and it was advice I got - is make sure you have a really strong grounding in the geology of the Earth. Because I think making sure you understand how complex planets are - and we certainly know that from the one we live on - grounds you in your ability and how you approach problems in planetary geology. And that has to be with a big slice of humbleness because we’re working in a sense with really limited datasets. I have radar images of the surface of Venus, I have some gravity data, I have a little bit of chemical data. Just think of how we would misinterpret the Earth if that’s all we had!  

I was working with one of my favorite planetary scientists ever - a guy named John Guest, who died a number of years ago - and he had worked on Mount Etna in Sicily his whole career. He and I were working on lava flows on Mount Etna and we had a radar image. He gave it to me and said, “You know, why don’t you make me a map based on the radar image?” And he was clearly setting me up, right? So I made the map, and he laughed for like 20 minutes because it was so wrong.  

But that really reminded me and drove home the point to be careful how much we interpret, and to always be aware that there are limits to what we can understand with remote sensing data. It doesn’t mean it's not worth doing, but there are limits. That’s why when you look at a program like the Mars exploration that we’ve been able to have, where we have a combination of orbital missions over time able to make a variety of measurements with a variety of sensors and get grounded truth from a number of different locations with increasingly complex instruments, it enables us to really start understanding a planet. And that’s what we need to do in other places like Venus, which has obviously been in the press this week.  

Speaking about that, I know that you’ve done a lot of research on Venus, for example as part of your doctoral thesis. What’s your opinion on the news about phosphine and Venus’s atmosphere?  

I think it’s a really intriguing result. You know, it’s long been speculated that there could be life in the clouds of Venus. I think that phosphine is an intriguing data point, but if you read the actual article, the authors are very cautious about overinterpreting it, and they said there are a number of potential sources both inorganic and organic for phosphine. And this really underscores the need to get back to Venus.  

The U.S. has not had a Venus mission since Magellan in 1990, and that mission ended in ‘94. Venus is a planet the size of the Earth. It’s the Earth gone wrong. You have two planets with such similar starting points that have gone down radically different evolutionary paths. We really need a better understanding of Venus, which means more orbital data, more chemistry data, more data of the atmosphere. And we’ve known for years that there’s an unknown ultraviolet absorber in the clouds of Venus. So is this phosphine related to that? Is that related to biology? Or could the phosphine be some weird chemistry coming from a lot of volcanism on Venus? We need to follow up and find out, because, to me, Venus really helps hold the key when we start looking for Earth-like planets around other stars.  

We had the Earth and Venus, and one became the Earth and one became Venus, and we’re really not sure why. Let’s go figure that out because that’s going to help us as sort of a platform to understand planets around other stars.  

Kind of following up on that, in 2015 you stated that you expected life outside of our planet to be found in around 20 to 30 years. Has your estimate changed since then, or is it still in that ballpark?  

It’s still kind of in that ballpark, which got way more press than I ever thought it would. It was funny because, at the time, I was the Chief Scientist of NASA, and Jim Green was the head of planetary science. They asked each of us in turn. They asked Jim Green, and he said, “Well certainly before I retire, we’re going to find it, definitely.” And then they asked me, and I said the same thing he did, but I just put years on it. If Jim had put years on it, he would’ve said within 20 years, right? Because he’s slightly older than I am, which means he’s almost 60. So we said the same thing, but I put dates on it.  

That answer is really predicated, frankly, on getting humans to the surface of Mars, which can happen by the end of the 2030’s. I think we can find a lot of indications of life before then, which is also what I was very careful about saying. Curiosity could still find something really interesting. The 2020 rover has a lot of instrumentation that could find really interesting indications. The Europeans are sending a mission to the surface in a couple of years that’s going to make some interesting measurements that could lead us forward. And if we get a sample return back, that could be really interesting.   

But my concern is this: to get past the level of argument in the scientific community is really hard. I mean, everyone thinks scientists love to agree, and you’re like, “That’s not really the way it works.” Scientists love to argue, they love to attack each other’s work. And so to get to a level where the scientific community really says, “Yes, there was life on Mars. Yes, we have some indication of what complexity it evolved to,” I think it’s not going to take one sample or one indication. It’s going to take a body of evidence, because that’s how science works. That’s why I think it requires humans on the surface of Mars who’ve broken up and opened a lot of rocks, made a lot of chemical measurements. It’s going to take that body of evidence to really convince the scientific community, and I think that’s late 2030’s, early 2040’s. But again, strong indications easily before then.   

Which upcoming mission are you looking forward to the most?  

You know, I think... definitely Mars 2020, getting safely down onto the surface of Mars. The fact that it’s going to catch a sample for future return to Earth is really exciting, I think. And then that Mars sample return mission – which is really two missions, they go hand in hand.  

And again, with each of those missions, I think it's going to move us further down towards evidence that life did evolve on early Mars. And the reason I feel somewhat confident about that is because the conditions on early Mars were so similar to those on early Earth, and life evolved so rapidly here after conditions stabilized. Well, if you have the exact same conditions somewhere else, why wouldn’t the same thing have happened?  

So going back to more school-related stuff: knowing all that you know now, what advice would you want to go back and give your younger, undergraduate-aged self?

Relax! I was always very self-critical and not very self-confident at those ages, and I just worried too much about everything. Was I going to be a good scientist, and then I got older and it was how do I balance my family and my work? My kids are now grown up, they’re all great, everybody turned out all right, better than all right.  

I think when you’re in the day-to-day struggle, it’s easy to lose sight of where you’re going. But I’m always telling people you need to really go with the flow, take advantage of every opportunity that comes in front of you, and don’t worry about so much. The ultimate goal is the path.  

Looking at your work history, it seems that you kind of went from more research-heavy positions to more administration-heavy positions. What led you to make that switch?  

I’m a co-investigator on the dragonfly mission to Titan. I still do a bit of terrestrial volcanology work when I have time. So I haven’t given up the research. But I think, as my career has gone on, I want to influence the outcome. For example, I spent six years working on a proposal to send a boat to the seas of the north pole of Saturn’s moon Titan. And it was because I was like,

“Well, the next thing we need to do is splash down in those lakes and see if there’s anything living in them and measure what they’re made of and how they’re interacting with the atmosphere.” And it's like, well, if that’s the next thing to do, maybe I need to step up and do it. 

So then you become more of an administrator, because you’re running a science team, you’re putting a proposal together. And that idea of not just working on the data but influencing what data is being collected was something I increasingly got involved in – the what and the how and the strategy.  

And as my career has gone on, I’ve certainly really focused on the fact that, through my career, I was one of the only women in the room... but really, I can only think of a few rare circumstances where I had a black colleague in the room, where I had a Latina or Latino colleague. So this idea that we’re not letting everyone in, that we’re leaving talent behind is something that has become, “Well, if I’m going to focus on something, maybe I should be focusing on that.” How do I help change it so that we get more diversity, so those people don’t have to feel like I did, like, “Why am I the only one in here? No one else here looks like me. Do I really belong here? Should I have to work twice as hard to be taken half as seriously? Should I walk into a room and have people think that I’m not there because of my ability but because, ‘Oh, we need a woman so let’s get one’?” You have to really struggle with that, and that’s wrong. And so how do I help be part of the solution to change that? 

One thing that I really enjoyed while working at the Smithsonian was when you made a comment once about how most people expect the director to be an old white man. I was like, “Wow, she’s right!”  

Well, it was interesting because the director before me was a wonderful man who’d worked at NASA at one point in his career. A military aviator, General Jack Dailey. He was a great guy! 

But being the first woman in the job... I wish it didn’t matter, I wish it wasn’t a thing, but to me, we’re constantly showing the women who come after us what the realm of the possible is. Because if you can’t see someone having done it, it’s harder and harder to imagine yourself doing it.  

Especially for most of us... I mean, you’re always going to have one unusual person. And I always tell girls, “You have to channel your inner Katherine Johnson.” You think of Hidden Figures and Katherine Johnson who, when she went into a room, she had this column of iron in her heart that said, “I don’t care what they think of me. They need me in there for my skills. So I’m going to walk into a room where I know half the people definitely don’t think I belong there - over half - and who are judging me by the color of my skin and the fact that I’m a woman.” And somehow we all have to find that little bit of Katherine Johnson inside of ourselves and say, “I’m going to walk in there.” But we shouldn’t have to. It shouldn’t be that way. And that’s why I think it is important to be able to say, “Well, someone came before me, so I’m following a path. I’m not a trailblazer.”  

I don’t really consider myself a trailblazer at all, but here I am.  

How has the field of planetary science changed since the beginning of your career, and how do you think it’ll change in the future?  

I think it’s definitely gotten much bigger, which is exciting. The questions have become more complex as we’ve gone on, which has been really exciting. We’ve had more missions, more data, which allows you to really push forward. I really feel like we’ve made huge progress and focused in on some key questions, like how does our solar system compare to other solar systems? How ubiquitous was life in our solar system, and how can we use that information to think about life beyond our solar system? So I think that’s been really exciting.  

I think there’s definitely more women, but they’re mostly white women. You know, I can still count my black colleagues on one hand. And that to me is an ongoing source of frustration. We are not doing well in reaching out to Hispanic and black communities and really getting those kids excited about the potential planetary science, the fun of it, and what it contributes. So I think we have work to do. It’s definitely gotten better, but the progress is slow.  

Final question, just for fun, if you could have a mission with unlimited funding and unlimited tech to go study anything anywhere in the solar system, what would that mission look like?  

It would be a mission to the seas of Titan, and it would be a combination surface floating probe along with a submarine probe that would allow you to really get down into those lakes and seas.