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Season 4, Episode 9: Is Our Solar System Weird?

Season 4Episode 9Jun 5, 2020

We now know there are more planets than stars in the galaxy. Many of them are very different from ours. How would we know if any of them had life? Shawn Domagal-Goldman, astrobiologist at NASA’s Goddard Space Flight Center, discusses these strange and wondrous worlds beyond our Sun.

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Scientists are finding planetary systems beyond the Sun that are quite unlike our own.

We now know there are more planets than stars in the galaxy. Many of them are very different from ours. How would we know if any of them had life? Shawn Domagal-Goldman, astrobiologist at NASA’s Goddard Space Flight Center, discusses these strange and wondrous worlds beyond our Sun. He and others at NASA are working on concepts for future space telescopes that could actually find exoplanets that resemble Earth, and detect chemicals that only life could produce. And what would such a discovery mean? Find out in this episode.

Jim Green: We now believe there are more planets in our galaxy than there are stars, completely changing our view of where life might exist. Let’s talk to an expert. Is there life beyond Earth on an exoplanet?

Shawn Domagal-Goldman: And if I’m wrong, I’m wrong, but that’s what we do as scientists, right? We can do that now.

Jim Green:Hi, I’m Jim Green, chief scientist at NASA, and this “Gravity Assist.” On this season of “Gravity Assist” we’re looking for life beyond Earth.

Jim Green: I’m here with Dr. Shawn Domagal-Goldman. He’s a research scientist and astrobiologist at NASA’s Goddard Space Flight Center. Shawn studies rocky exoplanets, and he wants to know about a planet’s surface climate, its habitability, and ecosystems. Welcome, Shawn.

Shawn Domagal-Goldman: Thanks for having me, Jim. I’m a fan of the pod.

Jim Green: Yeah, thank you. Well, you know the first planet another star was discovered in 1992. Now that’s not too long ago. And we immediately called it an exoplanet, and started looking for more of them. What do we know today about exoplanets?

Shawn Domagal-Goldman: Well, the first, for me, is that they exist. Because when I was born, there were none. We had, at that point, nine planets in our Solar System, and nothing beyond it. They were an idea. There was something we had talked about finding one day. And starting in ’92, we started finding them.

Shawn Domagal-Goldman: Now we know of literally thousands of them. And because we know of thousands of them, we also can start looking at them like a census almost, like how many planets of certain sizes are there, how many of certain orbits are there. And we’re starting to learn a lot of surprising things. We’re starting to learn a lot about how common Earth-like planets could be, although that Earth-like term is controversial. Basically, when we say that, how common are planets that are the size of Earth and get the same amount of energy from their host star that we get from the Sun.

Shawn Domagal-Goldman: So we can do that now. I can go out with my kid, look at the night sky, count stars, and tell her, that on average, there’s a planet for every star.

Jim Green: Wow. You know—

Shawn Domagal-Goldman: You couldn’t do that in ’92.

NASA's chief scientist Jim Green with astrobiologist Shawn Domagal-Goldman.

Jim Green: That’s right. You couldn’t. In fact, I think what was inhibiting the astronomers prior to that, was the concept as well. The planets are so small, we’ll never be able to detect them around a star, which as we see it, is just a point of light, and way far away.

Shawn Domagal-Goldman: Yes. So every detection method we have relies on seeing how that point of light from the star changes.

Jim Green: In some way.

Shawn Domagal-Goldman: In some way. Sometimes it dips, because the planet’s in front of it. The analogy I give is it’s like, if you’re of my age, E.T. and Elliot, flying in front of the moon, and blocking a lot. Or if you’re seeing an eclipse, the sunlight getting blocked, that when planets do that from far away, it just makes the star dim a tiny bit, and we can see that. Or, if the planet’s tugging gravitationally on the star back and forth, we can actually see the motion of the star towards us and then away from us, and towards us and away from us. But you’re right. No matter what we do today, with a couple exceptions, we’re seeing the star’s light change.

Shawn Domagal-Goldman: Eventually we want to see the planets themselves, because then now we can start to tease apart what the planets themselves are like. Not quite there yet.

Jim Green: Yeah. That’s the next big step. Well, as you said, we’ve found thousands of planets now. They’re confirmed, okay. And we now know there are more exoplanets in our galaxy than there are stars, which is another spectacular concept. Well what type of planets are they? And does every planet in our Solar System have a counterpart?

Shawn Domagal-Goldman: Every planet in our Solar System has a counterpart. But we might be the Portland of solar systems. Like, we’re weird, in that we don’t have a couple things that we see commonly elsewhere. And that’s actually thrown us for a couple of loops when we’re interpreting the data.

Shawn Domagal-Goldman: The very first exoplanets we found, they’re these things called Hot Jupiters. So they’re bigger than Jupiter, but they’re closer to their parents’ star than Mercury is to the Sun. So they’re really, really hot.

Jim Green: Yeah, and they could be on elliptical orbits.

Shawn Domagal-Goldman: They could be on elliptical orbits.

Jim Green: That was a really strange one.

Shawn Domagal-Goldman: It could be on a what’s called inclined orbits. So if you ever see that old picture of an atom, where there’s circles going in different directions. There’s solar systems where the orbits are inclined like that. You could almost imagine a system, and it probably exists out there.

Shawn Domagal-Goldman: The Hot Jupiters we found first. We didn’t know they were planets when we first saw them, because they were so foreign to our expectations. We had these predictions, there would be very few planets bigger than Earth, but smaller than Neptune and Uranus, because there’s nothing in our Solar System of that size. But it turns out that planets of that size, they don’t just exist, they’re actually the most common size planet we found out there.

Shawn Domagal-Goldman: So for everything we have here, there is an analogy out there. But the opposite is not true. There’s far more kinds of planets beyond our Solar System than we have in just our one example inside the Solar System, the ones that we have here.

Jim Green: Yeah. When this was really, early on, hot field and everyone was looking for exoplanets, I imagined that the planet that we’d find the most would be Jupiter-size planets. And that turns out not to be the case.

Shawn Domagal-Goldman: No. It ends up following what seems to be a sort of general rule of both stars and planets, that the smaller things tend to be more common. Although that may not be true down all the way to the Earth-size, but certainly down to the size of things slightly bigger than Earth. Those are more common than the really bigger things, like Jupiter and Saturn.

Shawn Domagal-Goldman: I should correct myself. There is one kind of thing we have here, that we haven’t found elsewhere yet. And that’s moons.

Jim Green: If we just are able to find a planet the size of the Earth around a star, and some Mercury-size planets around stars, finding moons has got to be a tough thing to do.

Jim Green: Well, what have we learned about our Solar System from studying exoplanets?

Shawn Domagal-Goldman: For me, I think, the lesson I’ve taken, is how our Solar has evolved, how the planets formed and changed their orbits over time. We thought, I think, when 20 years ago, before we found all these exoplanets, I think we had an image of the Solar System, I call it like a “peas and carrots.” You had the small stuff close in, and you had the big things back far away. And never shall the two mix.

Shawn Domagal-Goldman: But because we found these Hot Jupiters, these really big things close in, and we found some small things further away, we know that the evolution of these systems is much more dynamic than we ever imagined before. Knowing that, has informed our thinking of how our Solar System has evolved over time. People have taken improved models that can recreate those exoplanets and applied them to the Solar System.

Shawn Domagal-Goldman: And as a result, we can explain why Mars is the size it is, and has the orbit it does, much better, because now we think of these ideas of the gas giants moving in at one point in our Solar System’s history, and then moving back out. It’s that kind of thing.

Shawn Domagal-Goldman: We had a model. We had some physics. But we knew that the physics that caused that, was probably more common from having to use it to recreate the exoplanets. And then taking that back to the Solar System, we can tell a better story, a more comprehensive story of the planets back home, which I think is fascinating.

Jim Green: Yeah, it is. So let me flip that in asking, how has our study of the Earth and our Solar System informed us about exoplanets?

Shawn Domagal-Goldman: I think there’s a couple ways. One is a very real practical way, in that we have been doing decades of research on Earth, on our climate. We’ve been doing decades of research on the planets in our Solar System. And that gives us techniques to use. It gives us specific models.

Shawn Domagal-Goldman: My research, when I look at exoplanets or try to simulate them, the origins of the chemistry code that I use, goes all the way back to us studying the ozone hole in the late ’70s.

Shawn Domagal-Goldman: And we’re using that today, 30, 40, 50 years later, to study these exoplanets. And we’ve had lots of specific development along the way, to make it really good at the exoplanet problem. But it wouldn’t be possible if we hadn’t been researching Earth, and Earth’s chemistry, and Earth’s climate, 40, 50 years ago.

Shawn Domagal-Goldman: The other way that it’s really useful is, it gives us some framework when we look at these things. There’s a reason we call large planets close into their stars “Hot Jupiters.” And there’s a reason we call things between the size of Earth and Neptune “Super-Earths” or “Sub-Neptunes.” And scientists, sometimes we don’t like those phrases, because they can, perhaps, be too evocative, be too specific to some people. But for me, and I think for a lot of people in the public, it is a foundation upon which we can build an idea or a concept.

Shawn Domagal-Goldman: So sometimes just the language, even though it can be confusing sometimes and controversial, it does give us a starting point to have a conversation, around what is that planet like? It’s bigger than Earth, it’s smaller than Neptune. And that foundation of experience that we have with the things closer to us can be really useful.

Jim Green: Right after we started finding exoplanets, another new concept came up. And this was all about, well, a star’s light has got to be warming these objects. Where can we look in that exo-solar system, for planets that may actually harbor life? That term was called “habitable zone.” So how do we really define that today?

Shawn Domagal-Goldman: And folks, in the public, if you’re listening to this, you may have also heard that as the Goldilocks zone. You’re not too hot, you’re not too cold, you’re just right. It’s mostly based on the idea that life as we know it needs water. And if we want to look for life on a planet around another star, ideally you’d want a lot of water.

Shawn Domagal-Goldman: And the reason you want a lot of water, is you want a lot of life, so that way it can give off a huge signal that we could see from across interstellar space, against the background of that really bright star that the planet’s next to.

Shawn Domagal-Goldman: So we don’t want just life eking out a living in ice cracks somewhere. We want a big global breathing biosphere that’s going to give us a huge signal. And for that, what we really need is, like I said, a lot of water. So the science word for that is, we want liquid water surface oceans. So the habitable zone is all about the region around a star where liquid water surface oceans could exist. Because that’s what we think we need to get a really big signal from the biosphere.

Jim Green: Well there’s some real nuances in that.

Shawn Domagal-Goldman: Oh yeah.

Jim Green: In the sense that, when we look at our Solar System, we see Venus is too hot, Mars is too cold, the Earth must be in the habitable zone. But in reality, the Earth itself, with its climate, and with its atmosphere, is warming itself, through greenhouse gases. And in fact, it’s warmed itself to 80 degrees more than it would be without those important elements. And so it’s really in a habitable state, not necessarily in the habitable zone.

Shawn Domagal-Goldman: It changes over time. It’s possible Venus once was habitable. We think there’s evidence that Mars was, at once, habitable.

Shawn Domagal-Goldman: So there is, to borrow a Monty Python phrase, you can have an ex-habitable planet, where you might’ve had life before, but you don’t have it now. And that’s something again, we’ve learned from the studies of our planets in the Solar System. And it’s probably true for these exoplanets.

Shawn Domagal-Goldman: There’s probably planets out there that were not habitable, but might be today. Or are habitable today, but might not be in a million or a billion years.

Shawn Domagal-Goldman: There’s one other thing I should mention here, which is that a professor of mine, when I was a graduate student, Richard Alley, who is an expert on glaciation, and how glaciers change over time here on earth. He said something at a talk he was giving once. He said, “If I can tell the story of carbon, I can tell the story of Earth’s climate history.” And I would actually expand that. If I can tell the story of carbon, I can tell the history of Mars, and Earth, and Venus, in terms of their climate history. And I can also tell you the story of which planets could or could not have life, and those liquid water surface oceans.

Shawn Domagal-Goldman: An understanding of carbon is so essential to a fundamental understanding of climate. I can tell all of these stories, and I can make predictions, and they can be right, and I can be a rigorous scientist if I’m allowed to tell the story of carbon. If I cannot tell the story of carbon, I cannot recreate Earth today, or Earth a billion years ago, or Venus, or Mars in their histories, or these exoplanets in their habitable zones. Carbon is really essential to climate, whether it’s here or elsewhere.

Shawn Domagal-Goldman studies exoplanets and what kinds of worlds would be habitable.

Jim Green: Well taking that concept then into exoplanets, how might we identify life on those exoplanets?

Shawn Domagal-Goldman: That’s hard. Because the biggest challenge we have is, right off the bat, is a technical one. These planets are orbiting stars that are a billion times brighter than the planets themselves. So imagine you’re tracking a baseball, or a plane, or a bird in the sky, and it flies across the Sun. You get blinded.

Shawn Domagal-Goldman: As a scientist, I would say, the detectors, your eyeballs, are getting overwhelmed by the light from the star. The same thing will happen when we look for life on exoplanets. Because we want to block out the star light, just so we can see the light from the planet. And if we don’t do that, we’re going to get a billion photons from the star, just for that one precious photon from that pale blue dot.

Shawn Domagal-Goldman: And then once we do that, we’ve got an entirely different challenge, which is a scientific one, which is how do you take that one poetic pale blue dot, and say that it’s alive, or that it’s not. For that, we again actually look at the gases in the atmosphere. So we basically put that light through a prism. We get its different color constituents. We call it a spectrum. And then we look at that spectrum to see if it has gases that life produces. The ultimate test really, is whether or not that combination of gases is unique to life.

Jim Green: Yeah. So what are the combination of gases that we would observe in an exoplanet, that would convince you that there’s a biosphere there?

Shawn Domagal-Goldman: So there’s one combination in particular, that I would find very convincing, and most of my colleagues, I think, would as well. And that’s oxygen or ozone, which comes from oxygen, as well as methane. And the reason that’s a powerful combination is, those two gases tend to destroy each other, or lead to reactions that destroy each other.

Shawn Domagal-Goldman: The analogy I give to people is it’s like college students and pizza. If you see college students and pizza in the same room, you can make a pretty good guess that there’s a pizza restaurant nearby. The reason is college students eat pizza fast. And if you have pizza in the same room as college students, chances are somebody made a lot of pizza all at once, and brought it to the party.

Shawn Domagal-Goldman: And I can make a pizza. I can make a pretty good pizza actually, but I can’t a whole bunch of pizzas to fill a room full of college students, all at once. So in other words, the production rate of the pizza required to keep it there in the room with the college students is so high, you know there’s got to be a pizza restaurant nearby. And it’s the same thing.

Jim Green: So what’s happening then, is the oxygen and the methane get together so fast, the oxygen pops off the carbon, becomes carbon dioxide.

Shawn Domagal-Goldman: Right.

Jim Green: Okay. So then that destroys it. But if you find a lot of oxygen and you find a lot of methane, something must be producing it-

Shawn Domagal-Goldman: Yeah, fast.

Jim Green: And tells you that immediately.

Shawn Domagal-Goldman: And fast, yeah.

Jim Green: Because it’s there.

Shawn Domagal-Goldman: Yep.

Shawn Domagal-Goldman: And so that combination, that oxygen and methane, we see that in our atmosphere. You can take a spacecraft in the outer Solar System, look back at Earth, you’ll see it. You can look at the light bouncing off of Earth, and then off the Moon back to us, you see it. Oxygen and methane are here. We can detect them. And if someone was looking at us, that’s how they would know there was life here.

Jim Green: Well, one of the really exciting set of measurements that are being made on Mars is indeed, we see very small traces of methane, but we’re also seeing small traces of oxygen, and that’s a new observation. That’s really tantalizing.

Shawn Domagal-Goldman: Yeah. My colleague, Melissa Trainer, here at Goddard, was a big part of that. And this is one of those things. When we find the unexpected, it really pushes us to think really hard about what’s going on there? And when we answer that question, that’s when you learn something. And that’s what makes this fun.

Jim Green: Well what missions are being thought about that could actually make those observations in the future?

Shawn Domagal-Goldman: So the first one, and the one that I’m most excited about in the near term, is the James Webb Space Telescope.

Jim Green: Well that’s a real telescope. That’s going to happen.

Shawn Domagal-Goldman: That’s going to happen next year.

Shawn Domagal-Goldman: To be honest, we’re not expecting it to seek out signatures for all kinds of reasons. The types of exoplanets it’s going to look at are around these really violent stars that might blow away the atmospheres of the planets.

Shawn Domagal-Goldman: Even if we get some atmospheres that we see, having the sensitivity to look for these biosignature gases, is going to be a really tall order for Webb.

Jim Green: Plus it looks primarily at the really big planets.

Shawn Domagal-Goldman:

And it’s going to spend most of its time looking at the bigger planets. There’s an outside chance, so I can’t rule it out. But I’m not expecting it.

Shawn Domagal-Goldman: Longer term, I think our chances are better. Because this is such a hard measurement. I mean, this is part of what we do at NASA. We take a really hard challenge, and then we bring together really brilliant people on the engineering side, on the project management side, on the budget side, and we say, “How do we make this a reality?” And that for this, for this really hard question, I think we really need to start with the question, do these planets have biosignatures, and then design the mission around that.

Shawn Domagal-Goldman: We’ve got two concept missions. And that word, concept, is really important to focus on, because it means they’re not funded, they’re not things that have a specific launch date. They are things that are being considered by the scientific community at this stage.

Jim Green: Well that’s necessary to do, because you have to be able to figure out what it would be like if we built a mission to do this.

Shawn Domagal-Goldman: Yeah, we need to know, is a mission that looks, on signs of life, on planets around other stars, is that a unicorn, or is that a thing we know how to build?

Shawn Domagal-Goldman: And finding out how many technologies we need, and how hard that’s going to be. And if we got those, how long and how much money the mission might take to execute. Just so folks know, the two concepts I’m talking about are LUVOIR, which stands for the Large Ultraviolet Optical Infrared Telescope, and HabEx, which stands for the Habitable Exoplanet Imager, or Observatory.

Shawn Domagal-Goldman: Both of those missions would try to do this thing, where they block out the star light, get the pale blue dot, and then see if that pale blue dot has the gases that would constitute a biosignature.

Shawn Domagal-Goldman: With HabEx, what we’re talking about doing is, we’d like to find at least one pale blue dot, have a high level of confidence we’ll find one pale blue dot. And then roll the dice, and see what we see there.

Shawn Domagal-Goldman: With LUVOIR, we want to find up to 50, at the most ambitious versions of LUVOIR, 50 pale blue dots. And then start to do some systematic surveys of, how many of those planets have oceans? How many of those 50 pale blue dots have signs of life? And we can start to do statistics, and not just say, is life here on this one world, but how common is life in the universe?

Jim Green: Well, shouldn’t we be thinking outside the box, and looking for signs of life that are very different than what we know about, in terms of our own life?

Shawn Domagal-Goldman: Yeah. This is one of the questions that I get so often. If you’ve watched Star Trek, or Star Wars, or any scifi, you see these fantastical things, and then you come to a scientist like me, and I say, “Well I’m going to look for oxygen and methane, because that’s what we have on Earth.” It’s a tricky balance to play.

Shawn Domagal-Goldman: What we’re trying to do is, we’re trying to say, why is there oxygen and methane on Earth? And Earth was different at one point in the past, and it had life, and it didn’t have oxygen or methane. So one thing, I think you’re talking to Giada Arney later this season. One thing her and I have been working on, is we’ve been trying to think of what would biosignatures look like back on Earth when there was no oxygen, but there was still life. That would have been, what we call an alien biosphere, here on Earth, that we have recorded in the rock record. So we start with that.

Shawn Domagal-Goldman: And then from that, we start to tease apart, almost like a fundamental theory of biology. If I gave you as a planet, a certain combination of gases and a certain kind of energy source, what would the biology on that planet do? I say, we have to think like the planet, or think like the bacteria on that planet, what’s the best strategy for getting energy in that planet? And what would you make as a byproduct for getting that energy? And we look for that. So that’s the very generic version, or the general version that would be less tied to Earth.

Shawn Domagal-Goldman: But that’s also a model we don’t have. It’s just a model in my head, and in my colleagues’ heads, that we can talk about on a podcast. But we don’t have that numerical model yet that we could use. But we will have it by the time we fly the mission. But we don’t have that today. That’s cutting-edge research we’re working on.

Jim Green: Well everything we’ve been talking about, with these telescopes really interrogating planets, are all focusing on that search for life question. But let me ask you this. If we don’t find anything after searching with these telescopes, that indicate that these planets have life, what does that mean?

Shawn Domagal-Goldman: For me, this is what makes the search for life so much fun, because it’s profound, no matter what the result is. If we find life out there, that changes our view of ourselves and our place in the cosmos. But I think that’s also true if we don’t find anything.

Jim Green: I do too.

Shawn Domagal-Goldman: I mean, if we found that we were the only example of a biosphere out there, how precious is what we have here, and what does that mean for how we operate in our day-to-day lives going forward? I think we’d have profound impacts either way.

Jim Green: I do too, because to me, that would indicate, if we don’t find life like us at all, after many decades of searching, that maybe complex life like us ends up dying quickly, from a human perspective, is a sad thing to think about. But I would want to know that. I would want to use that in thinking of how we would change that paradigm, that we, as a species, could do that, because we have the ability to do that. And we don’t let what happens destroy us.

Shawn Domagal-Goldman: Well that’s part of where this becomes fun. Because we’re talking about exposing these questions to the scientific method, which means that we won’t stop at a certain point. So if we found there was nothing, what you’re getting at, is, we’d ask why.

Jim Green: Yeah. That’s right.

Shawn Domagal-Goldman: Why is there no life out there? And we’d learn from that.

Shawn Domagal-Goldman: The other part of this is, I am expecting, I cannot wait for all my models to be wrong, about why there is or is not life and what kind of life is out there, because that’s where we’re going to learn something about the interaction between a planet and its biosphere. And as you were saying, knowing that is going to change how we operate back here at home, and I can’t wait for that.

Jim Green: Yeah. I think so too. Well, okay, let me ask you this. Do you think we are alone in the galaxy?

Shawn Domagal-Goldman: I don’t, but more importantly, I’m going to prove it.

Jim Green: Wow, cool.

Shawn Domagal-Goldman:

That’s what’s cool, right?

Jim Green: Yeah. That’s right.

Shawn Domagal-Goldman: We’re going to go out, and we’re going to search. And if I’m wrong, I’m wrong. But that’s what we do as scientists. And we can do that now.

Jim Green: That’s right. So, okay. With that perspective, will we find evidence of life beyond Earth first in our Solar System, before we find it in exoplanets, or the reverse? What’s your thought on that?

Shawn Domagal-Goldman: That’s a tough one. What I’m doing right now, is I’m laying out the mission timelines on a chart almost. I think we’ll find life outside. I think we’ll find evidence of life outside the Solar System first. But I think we’ll be convinced that we found life inside the Solar System first. In other words, I think we’ll get the first paper saying, “Oh, I found something there, beyond the Solar System,” before we have that here in the Solar System. But I think the rigorous proof that will convince the full scientific community will come from inside the Solar System for this.

Jim Green: All right, so you personally, how would you react to the discovery of life?

Shawn Domagal-Goldman: Am I on the paper?

Jim Green: Well, if you are, then you’re going to defend it.

Shawn Domagal-Goldman: Yeah. If I’m on the paper, I’m probably popping a champagne bottle, and taking a long vacation. I mean, the immediate reaction, if I’m not on the paper, so I’m going to be taking a good hard look at it. I think if you’re trying to get at how I’d react once I’m convinced, whether I’m on the paper or not. If I’m on the paper, I guess this moment would just happen earlier, when I’ve convinced myself that the data are there. I think my first reaction would be kind of a sense of relief, just because a lot of my career is oriented around this search, and this is—

Jim Green: A sense of accomplishment.

Shawn Domagal-Goldman: Accomplishment, even if it wasn’t me, the fact that we did it, I would just feel relieved and satisfied. I’d probably plan a vacation, even if it wasn’t my discovery. And then, it’s so hard for me to break out of the thinking of a scientist. If I’m convinced, then I want to know, well what is that life like?

Jim Green: Yeah, it’s the next level of detail that you’re going to go into.

Shawn Domagal-Goldman: Yeah. On a more philosophical level, I think the other thing I’d start to think about is: how do we share this with the world? Because what I think would be more important to me is, if I was really convinced, I would want my neighbor to know about it, and them to be convinced and understand, from a scientific standpoint, what we’re talking about. Because we’re not talking about little green beings. Well, we’re talking about tiny green, like we’re talking about bacteria.

Jim Green: That’s how it might start, yeah.

Shawn Domagal-Goldman: And I think getting to that point, with my neighbor coming up to me and telling me about it, that’d be, I guess, my next goal, is I’d want someone on the street to come up to me and tell me, “Hey, did you hear about what NASA did?” That’s where I’d want to get to.

Jim Green: Well Shawn, I always like to ask my guests to tell me what was the person, place or thing that happened to them in their life, that got them so excited that they became a scientist, and they pursued intensely the field, in your case, of exoplanets. I call that a gravity assist. So, what was yours, Shawn?

Shawn Domagal-Goldman: My gravity assist was, I was in high school, and I was debating between whether I wanted to be a sports broadcaster, or some sort of academic. And I picked up a book called “The Case For Mars,” which was about sending humans to Mars one day. And that just, it blew me away. And the very end of that book, started to get into astrobiology, of this is part of what humans could do on Mars, is look for signs of life. And I thought that was, the idea that we could apply the scientific method to that question, it totally just got me focused on that.

Jim Green: Bob Zubrin.

Shawn Domagal-Goldman: Yeah, that’s right.

Jim Green: Bob Zubrin.

Shawn Domagal-Goldman: So that really put me on a path towards really wanting to pursue astrobiology actually, as a career. And there was one faculty member at my university that was doing research on that a couple of years later. So that’s what, Ariel Anbar, should give him a shout out here. That’s what set me down this path.

Jim Green: Yeah, fantastic. Well Shawn, thanks so much for joining me in this Gravity Assist.

Shawn Domagal-Goldman:

Thank you. And you, on the gravity assist thing, you gave me a gravity assist too. Because then, fast forward, I came and worked for you, years later. And I learned a lot about, not just how science is done, but how we lead science communities, and lead projects and teams. And that’s a big part of what we do at NASA too. And that’s, I think, it really set me up for a successful career here at the agency.

Jim Green: Well, thank you very much, Shawn.

Shawn Domagal-Goldman: Yeah. Thank you, Jim.

Jim Green: My pleasure.

Shawn Domagal-Goldman: Yep.

Jim Green: Well join me next time as we continue our journey to look for life beyond Earth. I’m Jim Green, and this is your “Gravity Assist.”


Lead producer: Elizabeth Landau

Audio engineer: Manny Cooper