Planetary Radio: Space Exploration, Astronomy and Science - Book Club Edition: Becoming Martian by Scott Solomon

Episode Date: August 21, 2026

Will we change or terraform Mars to better suit humans? Or are we more likely to change ourselves to better fit the red planet? How far can evolution take us in these new and exotic environments? These and many other fascinating questions are at the heart of Rice University professor Scott Solomon’s great book, “Becoming Martian”. He joins host Mat Kaplan for a far-ranging conversation in this month’s installment of Planetary Radio’s book club edition.  Discover more at: https://www.planetary.org/planetary-radio/book-club-scott-solomanSee omnystudio.com/listener for privacy information.

Becoming Martian, this time on Planetary Radio Book Club Edition. Welcome. I'm Matt Kaplan, Senior Communications Advisor for the Planetary Society, with more of the human adventure across the solar system and beyond. Which will be easier, terraforming Mars to better support human needs, or changing the humans who live there to be better adapted for life on the red planet. And will those humans change or evolve on their own, just as species have always adapted to new conditions on Earth? This fascinating theme is central to Scott Solomon's book,

Becoming Martian, How Living in Space Will Change Our Bodies and Minds. It was our July selection in the Planetary Society Member Book Club. Now, member or not, you get to enjoy my conversation with Scott, We spoke live in the community not long ago. Scott, welcome. Thank you, Matt. Happy to be here. We are really, really happy to have you, and it is an honor to talk to you.

Not only because of this great book, but because of the other great work that you are doing, to help get us ready to perhaps adapt to living on other worlds, which is what the book's all about. Let me read the bio that I pull together for you. Scott Solomon is a biologist, professor, and science communicator. He teaches ecology, evolutionary biology, and scientific communication as a teaching professor at Rice University in Houston. Scott is also a research associate at the Smithsonian Institution's National Museum of Natural History and a Sigma Zy distinguished lecturer. He has taught field biology in the savannas of East Africa, in the rainforests and reefs of Belize and

the Rocky Mountains of Colorado. His other book, Future Humans Inside the Science of Our Continuing Evolution was published in 2016. He also has two courses for everyone in the Great Courses collection of great courses. They're called Why Insects Matter and what Darwin didn't know, which is really cool. You also host the Wild World podcast, which explores the natural wonders of our pale blue dot. Here is what our friend Frank White of the overview effect says about becoming Martian. Scott Solomon has thought more than most about the topic of space exploration and human evolution. Everyone who is concerned about humanity's future on Earth and beyond will benefit from reading this book.

I was so delighted to get that very nice endorsement from Frank. Yeah, he's a good guy. Let me start with something almost irrelevant, except that you do open and close the book with it. I am so envious of you because you have witnessed not one, but two starship launches. Well, sort of. I tried to witness two. I actually successfully was present for one of them. That was a third, IFT3. I tried to watch the first one. had to head back home when they bumped it a couple of days. I forgot it was scrubbed. Yeah, right. Yeah, that's right. But the third one must have been,

I mean, obviously it was. You describe it. It was just spectacular. It was. And it was actually the only time I've ever been present at a rocket launch. So seeing the largest rocket that's ever been built fly was something else. And I got to bring my two sons, Nicholas and Thomas, down with me because it happened to fall over spring break. And so they were able to to come down with me and be there on the beach down in East La Blanca at the tip of South Padre five miles away and witness it. It was incredible. It is wonderful that the great Scott Kelly contributed the forward for the book and shared his experience and thoughts after, you know, living for basically a year in space. He closed with the hope that future Martians will never

forget the green hills of Earth, but also his worry that they may never be able to visit the home planet, which is something we'll talk about in more detail a little bit later. But that's obviously something that is disturbing. I mean, would you agree? I would, yeah. And I definitely think we will want to spend some time talking about why that might be the case. But yeah, getting Scott Kelly to contribute the forward was really incredible. I mean, I mean, who better to comment on the reality of what it's like to spend a long amount of time in space and also what we know about how space affects the human body and mind. Of course, being the subject or one half of the subjects of the NASA Twins study just made him the perfect person. So, yeah, it was really an honor that he offered to do that.

It sounds like you basically have been a biologist for, ever since you were digging in your backyard, right? Yeah, well, you know, there's this great quote by the oceanographer Sylvia Earle, who somebody asked her one time, you know, how do you get to become a, you know, a scientist who studies the ocean? And she said, oh, it's easy. You just start off as a kid and never grow up. And I think that's really true.

It's true for a lot of scientists, isn't it? And it was certainly true for me as a biologist. I always had a curiosity and an interest in nature. and science. And to me, those two are one and the same. You know, science helps us understand nature. And yeah, I was a kid who was always, you know, dreaming about going off on expeditions to wild places to learn about our world and what's beyond and doing what I could do, which was to, yeah, try to see if I could, you know, dig a deep enough hole in my backyard to find a T-Rex fossil or whatever, which, hey, that didn't happen, but that's okay. It kept me entertained and dreaming about what might come in the future.

What was it about evolutionary biology that really lit up your mind? I think I really discovered evolutionary biology in college. And it was actually not in a biology class, but in an anthropology class where I was learning about human evolution. And to me, it just was the science that was answering the questions that I didn't even know I was fascinated by. It's the why. It's the who are we and how did we get here kind of question. And why is nature the way it is? Why are these amazing species that we are surrounded by on our planet? Why are they the way they are? And evolution helps us to understand that. And once I realized that, I was just absolutely fascinated.

I was first interested in human evolution and thought I was going to pursue the study of human evolution for graduate school and for my career. but I sort of took some interesting left and right turns as often happens in, you know, education and wound up studying ants of all things. Yeah, but for me it was, it was really, you know, evolution helps us to understand why nature, why species, why life is as it is. And to me, that was the original hook. Speaking of ants, there are countless astounding stories of evolution here on Earth, but it's in the book. So like you, I have to say, I have been amazed and fascinated by leaf cutter ants since I first learned about them, topped only by actually seeing their long lines tromping through the forest floor in Costa Rica,

with their little bits of leaves, taking them home to their farm, their fungi farm. It's still jaw-dropping. It is. Yeah. I mean, they're fascinating. I think it's easy to get just sucked in by the, you know, the curiosity of what's happening when you see this. It's one of the natural wonders of the world. I mean, we think about, you know, Serengeti migrations or, you know, something like that.

But this is like that, but played out in. miniature. And yeah, I really got fascinated by them also by seeing them in, actually, it was also in Costa Rica for me the first time I really got to see them up close. And part of it, I think, is that they remind us of ourselves. I mean, they're doing things that are very human-like. As you said, they're growing fungi for food, right? They can't eat the leaves, so they're using the fungi to break down those leaves. And they're growing a crop. And they have a lot of the same issues with their agriculture that, you know, that human farmers have. And yet they've been doing this for 66 million years. So they've got a bit of a head start on us. So, you know,

there's a lot of lessons I think we might be able to learn that might be able to help improve human lives from studying ants. Turning more to the specific topics you cover in the book, when you first started to think about and then to write about and talk about how leaving Earth through the process of evolution might turn humans into a new species. Were you surprised by how that kind of went viral? I mean, you saw a tremendous interest in this topic. Yeah, and actually, it's ultimately, it's the reason why I decided to write this book, because I had sort of touched on it very briefly in my book Future Humans, which you mentioned in the intro. That came out in 2016, and I just at the very end of the book wanted to explore what might become of humanity in the long run.

And I looked at a number of different scenarios. Only one of them was what would happen if some people leave Earth and are permanently living in another place. As an evolutionary biologist, I saw that as a natural progression towards the evolution of a new human species. But I didn't go into much depth in that book about it. and yet when I started doing interviews or giving talks about that book, that was the thing everybody wanted me to talk about. I kept getting people asking me to say, okay, but tell us more about what's going to happen to us on Mars.

I think people are naturally curious about this topic. And it's one that, you know, for many years was something that seemed more like, you know, a little more speculative or a little more like science fiction. And as you know, that's not science fiction anymore. We are at a point in time in which I think we need to really seriously consider what the evolutionary consequences of living beyond Earth would be. So I think that's also part of why people might be so fascinated by it. It's not just a hypothetical anymore. You talk about this in the book by saying that you thought when you started this thinking about this stuff,

that it was just, you know, this is speculation about stuff that may never happen could be hundreds of years off. And then you started meeting space nerds like, you know, at the humans to Mars summit, which more about in a moment. And you started to, I guess, realize, hey, this may not be that far off. Yeah, that's right. I mean, you know, it's interesting to me because I'm somebody who, you know, I'm a scientist, I'm a professor. I like to think I'm relatively plugged into kind of things that are happening in science. And by the way, I live in Houston, right? You know, Space City.

And yet I still was really. not nearly aware enough of all of the things that were happening. I was really personally surprised by how much was happening. I'm talking about in going back to 2017, 2018, around that time, just all of the incredible things that were happening in space science, space exploration. I knew about a little bit, but there were so many things happening that I was not aware of. And I didn't realize how many people are really seriously working towards living in space. I think now today more people are aware of that. But still, when I I talk to people about this topic, there's still a lot of people who really aren't fully

plugged into all of the things that are happening. So, yeah, it's a fascinating time, as you know. Certainly. And speaking of humans to Mars, which of course now is humans to the moon and Mars, are H2M2. What do you think of Jeff Bezos' dream of a trillion humans spread across all kinds of worlds in our solar system. Wow. Well, I mean, I think it, you know, on one level, it sounds absolutely incredible, right? What a wonderful, you know, vision for the future where people could, could live in all of these places and just have that many humans and that many, you know, people doing amazing things. I always can't help but think about the biological consequences. That's how I got into this topic in the first place. So, you know, for me, my mind immediately

goes as, you know, I put on my evolutionary biologist hat to thinking about, okay, but then what, right? And so to me, you know, I keep going back to the analogy of thinking about islands. And whether it's a planet or a space station, if there are people living in a particular place with certain conditions and it's a certain distance from other places, those are islands. And we know that species evolve and change on islands. So the one thing I can't help but think in that vision of the future is that it is a setup for the diversification of future, generations of humans. And there's a lot to unpack when it comes to that, which I'm sure we'll get into. Yeah, I'll say. I was going to bring it up later, but you have a whole chapter, of course, titled

Cosmic Islands, which is a nod to Charles Darwin and the Galapagos, right? And all these observations, when you went to the South Pacific, to study these isolated groups of humans who lived on these islands, even though they made it from one to another, really charming also, by the way, when you were standing on that one island, Armaire, and realized that it basically was an ancient launch pad for Polynesians. Yeah, that was, I mean, that was a really special moment. So it was there on one of the islands in the French Polynesia near Tahiti. This is the site that is thought to be the jumping off point for many of the great voyages of discovery of the, you know,

the ancient Polynesians, who really were the world's most accomplished navigators. I mean, they found almost every habitable speck of land across the Pacific, which is just enormous. And they built these structures, these marais, as you said, and right there by the edge of the sea. And that would be the place that they would load up their canoes with all of the supplies that they would need to establish a new home somewhere out in the Great Beyond. They didn't know where they were going. It struck me as I was there that this is so similar to. what will happen if we get to the point where people are boarding rocket ships and heading out to other worlds to go and set up a new civilization there.

You know, many of the perils, many of the unknowns, many of the necessities of taking what you need with you and having to be self-sufficient along the way. In some ways, that's an old human story. We have been doing this throughout our history. And that also, as I try to point out in the book, means that, you know, I think there are lessons that we can learn from, you know, what the consequences were of those actions. But, yeah, it was, it was, it was pretty remarkable to actually be there at the moment and, and sort of realize that.

Tell me if this sentence in the book is another way of very succinctly encapsulating what you were, what you were after with this book. I wanted to see if our knowledge about evolution and about our species origins could help us to predict our possible future among the stars, which is a great line, by the way. Thank you. You know, that sort of encapsulates my approach with this book, was to try to use what we know about our past and what we know about how evolution works and what we know about things like how being in space affects our bodies and minds to try to make informed predictions about the future. This is something I try to point out often to my students when I'm teaching

evolution is that we tend to think of evolution as being about the past, right? Evolutionary biologists are usually trying to work out how evolution played out in the past so that we can understand, you know, why things are the way they are today. But evolution is also an ongoing process, and that means that we can apply what we know about evolution to make informed predictions about the future. We also have to be clear that we cannot predict anything with any certainty, right? There's always uncertainty, of course, about any predictions about the future. But I think that there's quite a lot that we can say about what's possible and what's likely. I'll have pause for a moment here. Take a look away from my own questions, which I've got lots of, and turn to our members in the member

community who are starting to submit some of their own questions and comments. Here's one from Sheila. Island Evolution was such a great analogy in the book. Really helped an engineering. understand biology. So kudos, I guess, to you, Scott, for that. That's great. That's great. John says, I imagine many of those lessons will be a hard learning experience. And, you know, reading about the Polynesians and knowing what they did, you have to wonder what percentage of them is they set out across an unknown ocean were never heard from again and never reached any kind of new island home. Hopefully we can minimize those losses as we kind of emulate them heading out into space.

Adrian says, none of this will happen without directed evolution and synthetic biology. Stay tuned to Adrian. Because maybe she pulled that right from one of the later chapters in the book, but we are going to get there. Back to some of the stuff that I've got. There's such a wonderful collection of people in the book, and I love how you share, sort of your personal experiences with these people that you learn from as you did your research. I bet you don't know that Matthew Shindell of the Smithsonian was also on the book club with his book for the love of Mars. Topics that we have talked about in the past in the book club and

many, many times on planetary radio about how challenging it will be to live and work on Mars, which is probably going to be the easiest place for humans to find and build a home elsewhere in our solar system. You distilled it into three overarching factors or challenges. Do those come back to mine? Oh, no. Put me on the spot here. The three overarching challenges. I should have warned you.

I might come up with three new challenges now. Well, here, you can tell me how close I am here. So, I mean, well, radiation. Yes. Size. Gravity, yeah. Yeah. And what was number three?

I didn't write down number three. I was going to say food might be a good third one. But I would say you could probably slice it a number of different ways. And now I'm not remembering how I sliced it by myself. How embarrassing. But yeah, you know, challenges in terms of what Mars really poses, right? I guess that's kind of what it is. Like, what is it about Mars that makes it a challenging environment?

certainly the radiation environment, and we can dive into that more perhaps. But gravity, I think, is the one that, to me, is the one that is likely to maybe be the biggest challenge because it's the thing that is the hardest to, you know, mitigate or modify. You can block radiation. You can provide shielding from radiation, a variety of different ways. And you can try to, you know, treat people to a certain extent if they've been exposed to some amounts of radiation. You can't really modify gravity, or at least we haven't yet successfully figured out ways to implement ideas for how to modify gravity. And it is the one constant throughout the history, not just of human evolution, but of all evolution on Earth for the last three and a half billion years, gravity has been

pretty much the same. And so organisms have never had to evolve or adapt ways to cope with either higher or lower gravitational fields. So there's just not any history there for our species or any others to use when it comes to, you know, trying to adapt to those conditions. We'll touch on gravity some more, but I want to pick up with radiation because there were some really interesting observations in the book about that. And by the way, I apologize. I promise not to put you on the spot again.

Yeah, that's okay. It's good to be quizzed. Hey, I'm a professor, so pop quiz is always a good thing in my book. Usually works the other way, though. I usually am the one asking the questions. You're right. That's okay. So like you, those classic renderings of the, you know, humongous glass or transparent domes covering huge settlements on Mars that were so enticing and so exciting in the old days. And yeah, I know there are still some people who we think we might still be able to get away with that.

Bob Zubrin, who will come up again, has some thoughts about that. But like you, the thought of, because of the radiation environment, having to live your life under meters of dirt is a lot less attractive than that nice transparent dome. And yet, apparently it might be necessary. Well, it's the easiest way to provide shielding from radiation is just to go underground, to use the Martian regolith as a shield for radiation. And, you know, we can either dig, you know, excavate caves, or we can, you know, pile regalith on top of our habitats, or we might be able to use preexisting caves or lava tubes, which are thought to exist on Mars.

So, yeah, either way, going underground seems to be. sort of the logical way to prevent, you know, people from being exposed to excess radiation. But yeah, that means living underground. You know, I've spent some time in caves and even a couple of lava tubes. And, you know, it's not really the kind of place that you want to spend a long amount of time. They're interesting to explore. But, yeah, I think that that would be very different from, as you said, the visions that people have often had of how a Martian habitat might look.

I was kind of flabbergasted when, because I'd never heard of it, when you described the discovery of this city called Darren Kuyu, if I have that correctly. Yeah, in Turkey. Yeah, underground city that may have housed 20,000 people. That just blows me away. Why would they do that? But apparently they did. Remarkable, I agree. And this is, you know, I've got a long list of places I want to visit in my life.

But as soon as I found out about it, that was definitely on the list. And there's a great story for how it was supposedly discovered, you know, in modern times when somebody was renovating their home and tapping on the wall or breaking through or something like that. And a hole opened up and they realized, oh, wait, there's something here. Yeah, there's not just something there. There's this entire, as you said, this entire underground city that had, you know, layers and layers going deep down. And I think the idea is that it was for protection, right? It was to hide and be able to stay for long amounts of time if there's, you know, enemies at the gate. But yeah, the point that I wanted to make in the book is that people have, of course, lived underground.

I mean, think about, you know, living in caves and other sort of underground structures. People have used that since, you know, the dawn of humanity, if not before. But we've always been able to come out. That's never been the place that we, you know, exclusively reside. And so it's one thing to use a cave as a shelter, even for relatively prolonged amount of time. I think it's an entirely different thing to imagine that is where you spend nearly all of your time, which I think is a more realistic vision of what it would be like to truly live on Mars. I guess we can hope that somebody discovers or invents a sunscreen that's like SPF 5,000 or something

and then just wear dark glasses. or anyway. Well, yeah, but you've got the, you've got the UV radiation, but then you've got all the galactic cosmic rays, right? Yeah, yeah. The other part of the problem. It would be sunscreen with a lot of lead, maybe. Who knows?

Back to gravity, because, you know, this is the main thing that made Scott Kelly's life so, so difficult, and that it got nastier as it went along during that very difficult year that he spent on the International Space Station. You talk about this at length, including what it would mean to be born on Mars. I think we might come back to that. We still don't really know, do we, if humans could really adapt to, let's say, a three-year round trip to Mars with a year getting there at zero-g and then be back in a gravity field. Yeah, maybe one that's only a third of what we have on Earth, but still, I wonder about those challenges. You obviously do, too. I do. Yeah. And I mean, there were a number of things for me that were really eye-opening about, on the one hand, we know a

tremendous amount about, you know, space medicine, about what happens to the human body in space. At the same time, that experience that we've had in space is in, you know, microgravity, effectively zero-g. And it's limited to a maximum of, I think, 400,000. 37 days is the record for the longest consecutive amount of time that any person is spent in space. So a round trip visit to Mars is going to take longer than 437 days. So we don't know what happens to a person's body when they're exposed to lower gravity for longer amounts of time. We can try to extrapolate and say, well, if this is what happens in this amount of time, we can kind of, you know, extend to the curve and imagine that we know what happens.

but we don't actually know. And as you point out, Mars has one third gravity that is different from being in microgravity. We really have very little experience. I say we as humans have very little experience in partial gravity. I mean, the only people who have really spent any amount of time in partial gravity were the Apollo astronauts. And what the longest they spent on the moon was about three days, right? So, you know, beyond that, we just don't know what being in part. partial gravity will do to the human body. Again, we can try to extrapolate based on what happens

in, you know, zero-g. But maybe one-third G is enough for our muscles to remain strong and our bones to remain strong as well. But the bottom line is that we don't know. I should note that even after all that he went through, and it was really, really trying physically and otherwise, Scott Kelly still looks forward to humans going to Mars. It's something that he talks about. You mentioned space medicine and how much we have learned. It was interesting to see you wrote that really this became a serious line of study back in the Skylab days, that first American space station. And then, of course, is continued with the ISS. Would you say that is it your impression that we really, we've learned a lot, but there obviously is still, as you've

just said is so much more for us to learn about what it's going to take. Yeah, I think that's true. So you're right. Skylab was really sort of the time in the American space program in which we started to really focus on understanding human health in the space environment. Obviously, you know, there was interest in understanding what was happening to human bodies when people were traveling to space before that. But, you know, it was interesting that, for example, during Apollo, NASA chose not to collect much in the way of biomedical data, largely after the Apollo 1 accident. And so they basically decided to focus on getting the astronauts to the moon and back safely. And they canceled a lot of the plans to collect biomedical data on those astronauts during those missions.

So we lost the opportunity to really learn much about what was happening to their bodies during those expeditions. Since Skylab, of course, we have learned a tremendous about. I mean, the NASA twin study with Scott Kelly and Mark Kelly, of course, being one of the better known examples. But there have actually been quite a few very detailed studies since then, including on the Inspiration 4 mission. There were some really interesting results, biomedical data, that came out of that mission, and many others since then. So we have learned an incredible amount, but it's limited to low Earth orbit, for the most part. It is limited to the amount of time, of course, that people have been able to spend in space. The number of people who have been to space is still, you know, relatively small.

And the diversity of people who have been to space is still quite narrow. And so that means that our general conclusions that we can draw about, you know, what happens to people in the broad sense are quite limited, right? You know, when we do science, we want big sample sizes and we want to, you know, maximize all of the, the different variables that we can to try to learn as much as we can. And we're just not there yet in many ways in terms of having a real robust knowledge of what will happen to people, especially as we venture farther into space and as we spend longer and longer amounts of time in space and as a greater diversity of people are spending time in space.

Now, that was something I thought about as you wrote extensively about the twin study, Scott Kelly and his brother, Senator Mark Kelly. It's still essentially a sample of one and would be nice if we'd had more. Some of the other conclusions, though, that the things that we've learned are also fascinating, like how microgravity and other conditions that you face in space are different from men and women. And where men do better in some areas, women do better in other areas. It's really fascinating. Was that surprising to you? Yeah, it was. And it was. And It's also, I mean, we should be clear, too, that it's based on not only total limited sample size, but there are far fewer women that have been to space. So that does limit what general conclusions we can draw.

But yeah, there's interesting things like women apparently tend to be more likely to have motion sickness in space, but then do, you know, better in other areas. So, but I really want to emphasize how small amount of data that we really have, right? as a scientist, we're always trying to be very cautious about drawing general conclusions from small sample sizes. So we really need to get more. And of course, a wider age range. I think that's the thing that really struck me the most is that what we know is only about adults and it's really only about healthy adults and it's really only about healthy adults and within a relatively narrow age range. And once you get beyond that, our knowledge is really quite limited. And again, we get into the realm of extrapolation and guesswork. But if we're going to be living in space,

we really need to know what happens to everybody. I'm going to cut away for another couple of comments and questions here from our members again. I love what Arnold had to add. Very fascinating exploration of the challenges of evolution of humanity in the universe. And then he mentions my conclusion, like yours, Scott, comes from Skagin's contact. when Ellie's alien avatar, the guy who looks like her father, advises her small steps, Ellie, small steps, which seems like a very prudent course. Jeff says, is there any research in artificial gravity, spin gravity for space travel?

Shockingly little, in my view, even though we've seen it in lots of science fiction stories, including the Martian, we really have not done much, not just the Martian, but now Project Hail Mary, to explore how we might provide a sense of gravity to astronauts. Did that come up in your research? Yeah, I did. And I think it's a very, very good point, a very important point, because, you know, we may discover that we need a certain amount of gravity. It might not be one G. You might not have to have full Earth gravity, but maybe we need to have some amount. Maybe it's one-third G. Or maybe it's, you half a G, for example, in order to have a child be able to fully grow and develop into a healthy adult. We don't know that. And so if it turns out that that is necessary, we would need to find a way

to increase the amount of gravity that people are experiencing if we're ever going to, you know, truly live beyond Earth. So until we're able to do that kind of research, we just don't know if we're going to be able to truly live in a way that is sustainable beyond our planet. So one of the things that I did follow in researching the book, there's a company called Spaceborn United that is trying to make some advances in the study of human reproduction beyond Earth. And they have invented a device that can spin to provide different amounts of simulated gravity. and their idea is to test how fertilization and the first few steps in embryo development are affected by different gravitational fields. So the idea is if you launch this device up into low Earth orbit and then spin it at different speeds, you can have lunar gravity, you could have Martian gravity, you could have any amount of gravity that you would like, even going beyond 1G if you want to try that.

And then look at how fertilization and embryo development proceeds. So that was sort of the one example of a group of people who are trying to take that idea of creating artificial gravity and then using it to do some science. And so they're still in the early stages of doing that research. But it was fascinating to follow along and see what their ideas are, what they're doing. And I'm excited to see what they find. I'm going to come back to this as well because you devoted a whole chapter to whether humans will be able to reproduce on Mars or. in microgravity and the children, the challenge that they will face. But if we look at the other end of the human age span, I've got five years to go till I'm as old as

John Glenn was when he got to go up on the space shuttle. That's kind of encouraging. I don't have a lot of hope left, but I'm hoping someday that I'll still make it. He did pretty well, didn't he? I mean, they did a lot of research on him while he was up there. That's right. Yeah. And this was, you know, something that was really fascinating to me to read about that research, but also to speak with Scott Parasinski, who's retired NASA astronaut, who was assigned to be essentially John Glenn's personal physician in space on that mission. And this was one of several instances in which being in Houston really ended up being the ideal place for me to be while researching this book. Because I happened to meet Scott Parasinski basically by accident. I was having, coffee near Rice University one day and talking with my friend John Yuri, who works at NASA Johnson Space Center. And this was early in the research stages of my book. And John was offering to

introduce me to some of his colleagues at NASA. And I was like, oh, that'd be great, John. I'd appreciate that. And he goes, hang on a second. And he gets up and two tables over is Scott Peresinsky, who's sitting there having his own coffee. And so he calls me over and introduces us. and Scott Berazinsky became a wonderful contact and resource and has become a friend as well. So I got to hear from him about what it was like to be up there with John Glenn and to help him not only to stay healthy, but also to do some of the science to kind of understand what was going to happen to him in the conditions of space. But yeah, he did well.

I think from what I heard, the only real thing that was maybe a little bit different about him compared to the younger astronauts was sleep. It might have been a little bit harder for him to sleep, but that's already something that's challenging for a lot of folks in space. And it was a nice anecdote to read that Parasinski's talking about how this guy, the original right stuff, John Glenn, didn't care for needles. And there were a lot of needles involved in the work. That's right.

And there were a lot of jokes about all the blood draws that he had to do as part of the the biomedical research, but he did it. He's a tough guy. But what about terraforming Mars? That topic and much more are ahead after a very brief break. Hi, Bruce Betts here, Chief Scientist at the Planetary Society. Our organization is strongly committed to defending our planet from an asteroid or comet impact. Thanks to the support from our members, we've become a respected independent expert on the asteroid threat. So when you support, us, you support planetary defense. It's a lot to do, and your support is critical to power all this work. That's why we're asking for your help as a planetary defender. Together, we're advancing the

global endeavor to protect the Earth from asteroid impact. Imagine the ability to prevent a large-scale natural disaster. You can be part of this global effort. A gift of any amount to the planetary society helps keep this critical search going, protecting our planet and everyone on it. Visit planetary.org slash defend earth to make your gift today. Thank you. I switch gears slightly and turn to a topic

that you mentioned in the book, which is near and dear to my heart. And that's the topic of reshaping Mars to basically make it more fit for human life. Terraforming, of course.

Robert Zubrin, founder of the Society and the case for Mars writer, amazing guy. We've had him in the book club as well. You talk about his speculations about terraforming, including Carl Sagan's. They're both pretty positive about it. I have a bet that I've talked about before with our former CEO and now our chief ambassador, Bill Nye, the Science Guide. I have bet Bill that within 10,000 years, we will terraform Mars. And there's there are five dollars. writing on that bet. But those $5 are going to be worth a lot more by the time that bet is realized, right?

I sure hope so. We should have invested the $5 bill instead of just putting it on a wall. You're absolutely right. I mean, this is kind of the, what, the obverse of what we'll get into talking about and later in the book, which is humans being reshaped to fit the environment. What did you learn from people about changing the environment so it's more? more so it's friendlier to the way we are right now. Yeah, this was an interesting thing for me because I, you know, of course,

it heard about the idea of terraforming, but I didn't realize kind of how many different versions of terraforming there could be, right? So there's the idea of terraforming the planet so that it becomes so earthlike that we could walk around outside the way that we do, you know, here on Earth. But then there's other versions where, you know, you might still need an oxygen tank. In other words, the atmosphere wouldn't be breathable, but you wouldn't need a pressure suit, right? And so there's that possibility. There's the possibility that you could have, you know, plants growing outside on the surface, but maybe not animal life.

So there's sort of different versions of it. But the thing that really struck me was the idea that all of those visions of modifying the environment on Mars to make it more Earth-like, it's not that they're not achievable. There's many ways in which they might be achievable, or at least some of the more modest versions, definitely do seem like they could be achievable over a long time span, as you point out, but that they also are temporary. And this was something that I didn't fully understand until it was really explained to me, the idea that, you know, Mars being a small planet and having a lower gravitational pole and not having a magnetic field, that result, in its atmosphere being stripped away by the solar wind. And so whatever you're putting into the atmosphere to increase its density and to potentially provide, you know, breathable gases for humans or for other organisms, those are going to be stripped away by the solar wind.

And that means that you have to be replenishing the atmosphere. So it's not enough to do it once and then just let it go. You have to keep providing more of those atmospheric gas. And that strikes me as a problem if the way that you're going to introduce those gases is to do things, for example, that Robert Zubrin has proposed, like redirecting an asteroid to collide with a planet or detonating nuclear weapons at the poles to vaporize the carbon dioxide and water ice that's frozen there. Those are things that you may very well be able to do before the planet is habitable. But once you've got people living there, it becomes a lot dicier. So that's the thing that strikes me as maybe the biggest challenge of terraforming is not doing it initially, but maintaining it. Constant maintenance of an entire planet.

Jeff adds, speaking of terraforming, the future Martians would need to pollute like there's no tomorrow. Yeah, I mean, you're basically having to add carbon dioxide to the atmosphere and other, you know, greenhouse gases, the things that we're trying to minimize on our planet at the moment. So many other challenges, though. I mean, the perchlorates, that soil that, you know, even if you, you mentioned in the book, even if you grew potatoes in them like the Martian does, those potatoes might kill you. There are so many challenges. And it makes me also think of someplace that I. I've had several invitations to, still haven't made it to, you write about Biosphere 2 in the book. I am.

And even though it was, in many ways, a failure, we learned an awful lot from it, didn't we? Yeah, it's interesting because I think you're right, it has a reputation, you know, often of being a failure. But in other ways, it was, it was not. You know, you can really think of it as a success in that, you know, the idea was to have a crew of eight people hermetically sealed in side for two years and to be essentially self-sufficient. And, you know, in many ways, they achieved that. I mean, they did emerge two years later, you know, all eight crew members. They survived. They had quite a few challenges. And to me, that was the most interesting part of it is learning from the challenges that they experienced. Some of them were physical challenges. Others were interpersonal

challenges. But, you know, I mean, they, essentially they split into. two factions that were, you know, unable to speak with one another from what I understand. So, so that's obviously an important lesson that we need to learn. You definitely want to avoid having that kind of thing happen on any kind of, you know, space settlement. But yeah, at the same time, I mean, it was a very ambitious plan, a very ambitious idea. They did manage to stay inside there for two whole years and nobody has ever since replicated anything quite that ambitious. And you talk about other analog astronaut efforts as well, of course. Have you noticed how the types of people who are made astronauts, chosen to be astronaut,

has also evolved over the year, sort of directed evolution, kind of, from, you know, those guys who had the right stuff, but weren't always the, you know, the nicest people to be around. Many of them were, but some were not. till now the astronauts that you meet who get to go to the ISS and do other stuff, they are the nicest people in the world. And it's very much on purpose, isn't it? Yeah, that's right. And I think it does say a lot about what we have learned about what works in space.

Part of it is they're going on much longer missions than they initially were doing that, you know, the right stuff era, right? Those were relatively short duration missions. And the longer that you're going to be up there in a confined, isolated, hostile environment with a relatively, well, a very small number of other people, you know, it really matters who you send along with you. And it really matters how well you get along with those people. And so those crew dynamics we now know are absolutely essential. So I think crew selection, you know, who you decide to send is something that, you know, NASA and other space agencies have learned to really take very seriously.

And of course, that will matter for Mars missions. And of course it will matter for talking about space settlement. But at the same time, there will be other considerations that we'll have to take into account if what we're talking about is not a round-trip visit, but a one-way, you know, stay. In other words, people who are going to go to Mars or anywhere else to establish a human settlement, You know, who you choose to send on that type of a mission really matters, not only for how the crew, how the, how the people will interact and how well they'll get along with one another, but also because you are then basically planting the seed for the future of that entire population. And so you have to take into account things like the genetic diversity of that population, because we know from evolutionary biology that that really matters for the future success of a population. I was surprised to see that you wrote in the book that the thinking is that you can have as small of a human community as 10,000 individuals if they're carefully chosen. And you could still maintain the kind of diversity you would need to really establish a long-lived society.

Do I have that right? Yeah, that's right. And we think that probably throughout human history there has been, you know, even smaller settlements. We were talking about the Polynesians earlier, and they certainly had nowhere near 10,000 people that were aboard the canoes that were going and establishing a new settlement on a new island. So having a small number of individuals creates a challenge. It creates, you know, what we call a population bottleneck in biology. You've reduced the amount of genetic diversity, and genetic diversity is the raw material that natural selection uses to allow a species to adapt.

and change. So the number does matter because the more number of individuals, the more diversity you're going to have. But if you also choose those individuals deliberately to try to maximize diversity, you can kind of increase the odds that that population is going to be set up for success. Right. So, yeah, we would have to choose the people to establish a human settlement in a way that I think is quite different from how we've historically chosen crews, for space missions. We have to consider not only how they're going to perform and interact with one another, but we have to consider other aspects of who those people are, their genetic background, the types of traits that would be basically laying the foundation for what's to

come in future generations. You mentioned in the book it would be smart to bring lots of Africans or people of African descent, because Africans tend to have more diversity in their genomes? So if you sort of take the entire continent of Africa, so it's sort of easiest to sort of, you know, break up human diversity by continents. And the continent of Africa actually has more genetic diversity than all of the rest of humanity combined. And this is because our species originated in Africa. And relatively small numbers of individuals made their way out of Africa and went on to go and settle the entire rest of the planet. But what that means is that Africa is still the home to the greatest amount of genetic diversity anywhere. So yeah, if you wanted to sort of at a first

approximation say, well, where should these populations be drawn from that are going to go and establish a settlement on Mars or anywhere else beyond Earth, you know, would do pretty good by, you know, making sure that Africans were included. And you certainly wouldn't want to exclude them because you'd be excluding a tremendous amount of human diversity. And, you know, even just selecting only Africans wouldn't be the worst idea. You'd do a pretty good job of representing human diversity that way. So 10,000 people isolated on Mars. It won't be long before their fooling around, what is the latest thinking on whether humans will be able to make healthy babies in space or on worlds like Mars, especially if you don't have a centrifuge on orbit or something

that you can send mom to for nine months possibly? To me, this was the biggest surprise in doing research on this book, because I think this is potentially the showstopper, right? Like, if we can't reproduce beyond Earth, then we can't live beyond Earth, you know, full stop. So I was surprised by how little we actually know about any aspect of human reproduction in the environments of space. You know, there have been some studies on animals in both, you know, in space and in simulated space conditions, but very few. And the results are largely inconclusive. So we don't actually know if it will be different. In other words, if each of the steps that are necessary in reproduction, starting with sex, going to fertilization, going through

development and pregnancy, birth, and then child development, growing up into a healthy adult. Each of those steps potentially could be affected by lower gravity or by other conditions like higher radiation. And if they are, we need to know how they're affected and whether we can mitigate against the effects. So, you know, the bottom line is that this, in my mind, is probably our biggest blind spot when it comes to our possible future beyond Earth. There are many possible ways in which human reproduction may be affected by the conditions of space. But the bottom line is that we really just don't know. Here is another great line from the book. Natural selection

is a cruel process, but it works. And it never stops. working. You've already touched on this in our conversation tonight, and of course it comes up many times in the book. Are you utterly convinced that evolution will proceed, natural selection, will proceed as it has for billions of years on Earth when humans go to live on Mars? Yeah, I think this is really in many ways my biggest take-home message in this book, is that if we go and live anywhere beyond Earth, we should expect. evolutionary change. That should be the default expectation. It shouldn't be a surprise to see that future generations differ in some ways from the initial people that go and establish those settlements or

differ from people back on Earth. And the reason I say that is because everything that we know from the study of evolution tells us that you take a small number of individuals and then you put them in a new place that has a different environment that is far from home, that that is a perfect recipe for evolutionary change. I mean, this is why biologists since Darwin have gone to islands like the Galapagos to study evolution, being in an isolated environment that is different from your home, that is a recipe for evolutionary change. So yeah, I do think that is what we should expect to happen. In terms of whether it would happen the same way that we're used to, I think in many ways, the laws of evolution are not something that you can change.

You know, there are certain principles of evolution that would apply to any species under any circumstances. But something that could be different is the rate. How quickly would people change? And I argue in the book that we should expect a faster evolutionary change for people living in the conditions of a space settlement, including on Mars, in part because the environment is so different from Earth, and when an environment is very different, that means that basically natural selection is stronger. It's operating to more rapidly create

adaptation. But it's also possible that just having any amount of radiation exposure that is higher than what we are used to here on Earth would increase the mutation rate. And mutations ultimately are the raw material that natural selection can use. So that's another way that could basically jumpstart the evolutionary process and accelerate evolutionary change for people living beyond Earth. This touches on this very common misunderstanding that evolution is something you're not going to see much of a difference unless you've got thousands or possibly millions of years to hang around. And as you've said, not necessarily true. Talk about this great example you've given the book about tuskless elephants. tuseless female elephants.

Yeah, it's funny because I wrote about that in the book, and then I actually got to experience and see this personally after I had finished writing the book. So this is, in some ways, it's a really sad story because what we're talking about is a group of elephants in Mozambique, in Southeast Africa, and Mozambique suffered a very long and tragic civil war for many years. And during that time, you know, there was a lot of desperation,

people trying to find food, people trying to make a living. And elephants, unfortunately, ended up being in the crossfires. They were being killed in part for their meat and in part for their tusks, their ivory as a way to make some money. And the poaching of elephants was so high that any elephant that had tusks was very likely to be killed. And it turns out that there is a mutation in. the elephant population that naturally occurs that results in a female elephants being born without tusks. That mutation existed in the Mozambican elephant population before the Civil War, but during the Civil War, any individual elephant that had that mutation and was born without

tusks was much more likely to survive because they were less of a valuable target if you couldn't kill them and retrieve their tusks for ivory. So what that meant is that those tuskless elephants survived longer, had more offspring passed on those genes for being tusclous. And now the population of elephants in Mozambique has the largest percentage of tusclous elephants anywhere in the world. And I did actually get to see this firsthand. I had the opportunity to visit Mozambique last year and visited Goring Goza National Park, the spectacular park in the center of the country. And at one point, we actually got charged by a group of elephants, which was a somewhat terrifying, but also thrilling experience.

And I'm there, you know, as the biologist, like, you know, we're in the back of a safari vehicle, and I'm filming this, and I'm looking at this, you know, elephant running us down. And then the group of elephants formed a protective ring around the young. And I'm like, oh, my God, look, they're tuskless. So, you know, that was, to me, the most salient thing was, I was. was thinking about it as an evolutionary biologist after I was sure that we were all safe. After you were at a safe distance, I hope. Let's turn to the importance of the microbiome. And, you know, why bringing along the right bacteria and viruses may be the difference between

life and death in a Martian colony? Yeah, well, this is something that, you know, when I'm teaching biology to college students, I often tell them, this is probably, our biggest revelation in the last few decades in the field of biology, certainly one of the biggest revelations, is how abundant microorganisms are in the world, how abundant they are in and on our bodies, and how absolutely essential having those microorganisms in our bodies is for our health and our well-being. So the whole idea of the microbiome is something that we've only really come to understand in the last few decades. And we're still trying to fully understand it, to be honest.

But the point is we bring microbes with us everywhere we go. And that's a good thing because we need those microbes, or at least many of them, in order to be healthy. So we will bring our microbes with us to space. We do, astronauts who go to the ISS, for example, are carrying their microbiomes with them. And we'll bring them with us to Mars. It will have to if we want to survive.

But I also think that we need to be very clear about the fact that we are going to be living in space in an environment that is very devoid of microbes. Right. I mean, in other words, we're only going to have what we bring with us. We are used to living in a microbial environment. And in fact, that's how we acquire our microbiome is from the environment and from our parents, our mother in particular, and from other individuals. that we interact with. So where will our microbiome come from when we're living on Mars? It'll be passed from one generation to the next to a certain extent. But the problem is you can't just acquire new microbes from the environment because as far as we know, there are no indigenous

microorganisms on Mars. So we'll only have what we bring with us. But if we bring them along, We've already learned, as you tell us in the book, the bacteria and viruses, they're pretty good at evolving themselves, right? Which could present another big challenge, couldn't it? It could because those microorganisms that are currently friendly and helpful could evolve to become, you know, dangerous parasites or pathogens. And in fact, we know that this does happen from time to time. So some of those microorganisms could sort of turn on. us. We should expect that they evolve. I said before that we should expect evolution to be the

default if we leave Earth. And it's not only true for our species. It's true of any other species we bring with us, whether we bring them intentionally or they're, you know, along for the ride as sort of hitchhikers. So yeah, they're going to be evolving and changing. And that might be in ways that could be helpful to us, but it might not be. Very near the end of the book, you bring up the challenge of those microbes that might make their way to Mars accidentally if somebody, you know, goes to visit grandma for, you know, half a year whose grandma who's been living on Mars and, you know, left when you were still a kid. I think of, and you mentioned the example of the War of the Worlds. And I love that finish, of course, how everything that those late 19th century

Earthlings tried to kill off the Martians was no good at all with their advanced technology, but the Martians hadn't planned on meeting the bacteria on Earth. And of course, that there would be this similar danger. What if somebody brings a microbe to Mars to a Mars colony? That Mars colony, which has been, let's say, completely free of measles since its beginning, is suddenly faced with possibly with an epidemic. I mean, it's a lot like, as you point out, the devastation that took place among Native Americans when Europeans showed up. Yeah, well, you actually, you brought up two things there that I think are really worth pointing out.

And one is that there is, I really think there's an opportunity if we do decide to live beyond Earth to try to, you know, not bring certain diseases with us, right? I think there's an opportunity to escape from some of the diseases that plague us here on Earth. you know, there's a lot of ways that we could do that very deliberately, right? I mean, we can have quarantines. We can also not bring the vectors of those diseases. Think about something like malaria, right, being transmitted by mosquitoes. If we can avoid bringing mosquitoes with us to Mars, which I'm very much in favor of, then we can presumably avoid having to deal with, you know, malaria, yellow fever and all the other diseases that mosquitoes spread. So that's a real opportunity. But at the same time, it does create the set of

up for what you were just describing, which is now you have a population of people living in a place and their immune systems would be naive to those particular infectious diseases. And we know from history that any time people who have had no history of being exposed to a particular disease are suddenly confronted with that disease, that there are often very deadly consequences. So I worry about in that direction, but I also especially worry about the reverse direction, meaning a person who is from Mars, you know, imagine a child born and raised on Mars coming to Earth, all of the diseases that we have here on Earth would be potentially quite dangerous for that person. So I do worry that infectious disease really could be a major limiting factor when it comes to the

possibility of people going back and forth between planets once we've established settlements there. challenge after challenge. It brings up thoughts of the great book by Kelly and Zach Wienersmith, A City on Mars, and they're friends of yours, I know. We also had them in the book club. It's a very sobering book, very entertaining, as you would expect from the Wiener Smiths. But this thought that, you know, they started the book as total space geeks thrilled about writing about establishing colonies on Mars. And by the end, they were kind of pessimistic to the disappointment of a lot of the

people that they talked to. I mean, where are you in that spectrum of belief about whether humans will someday live on Mars? Yeah. So as you pointed out, yeah, Kelly and Zach are friends of mine and I talked with them quite a bit in the process of researching this book. Kelly in particular, who's a fellow biologist and a colleague at Rice. And so, you know, partly, I guess I benefited from their experience because they were researching and writing their book, you know, a couple of years before I was. And so I had read an early copy of their book, even as I was working on mine. And so I sort of, to a certain extent, was probably affected by their journey and their

experiences. But I also experienced some of the same thing myself in doing the research where I, you know, I was, and I am still enthusiastic about the idea of sending people to space, about doing the science, about doing the research to learn more and more about what happens to our bodies in space and about the idea that someday we may be able to live in space. But the more that I learned, the more it became clear to me that we're just not ready to do it yet. I think, to be clear, I think we are absolutely at a point where, you know, sending people farther into space is something that is not only doable, but something that I think we should

be investing in. I think the science that we can do today in deep space is absolutely fascinating, and we'll learn a lot from it. But my real concern is the idea of getting too far ahead of ourselves when it comes to the idea of actually having a city, right, having a settlement, having families, raising children. That to me is the point where I start to worry because, you know, it's one thing for an adult to understand the risks and to consent to going and taking on some risk in the context of human space exploration. A child can't do that, right? and certainly not an unborn child. And so when we're talking about having families,

I think we need to get to the point where we understand the risks and we can mitigate them as much as possible before I would be comfortable with the idea of actually raising families there. So it's not a matter to me of whether we should ever do it. It's a matter of when, you know, what's the time frame for doing this and making sure that we're really being responsible about it and not too far ahead of ourselves. There is one more topic I want to bring up.

We've talked about how Mars may change us, probably will, but also how we might direct our own evolution or adaptations in this chapter that you called the next humans. And in that chapter, you talk a lot about your interaction with this guy you met named Chris Mason, who was given a lot of thought to this. And this field, which correct me if I'm wrong, did he name it? Deontogenics, could you talk about why he thinks this is going to be so vital? Yeah, Chris Mason was one of the people I was really excited to get to speak to and visit, actually.

So he is a researcher and professor at Will Cornell Medicine in New York. He was one of the researchers on the NASA twin study and continues to be really one of the leading researchers when it comes to the field of space genetics, the study of the space microbiome, and the idea of genetically engineering life to enable space exploration. So I had an opportunity to go and visit him and get to know the folks that are working with him in his lab and talk with him quite a bit about not only the work that he's doing, but about his thoughts about where we are today in human space exploration, and what it might take in order for us to really realize this idea, of space settlement. So he's written quite extensively about this, including a book called The Next 500 Years,

which is a really fascinating book that basically lays out a blueprint for how we could use genetic engineering to enable space exploration, but not just exploration, space settlement. And he sees it as really a moral imperative, the idea that because we have the ability or may soon have the ability to spread life beyond Earth, that we have an obligation to do that, right? The idea that if we don't take life and make it interplanetary, not just human life, but all life on Earth or as much of it as we can, that eventually some disaster here on Earth might result in the extinction not only of individual species, but potentially of all life as we know it. So it's a really interesting philosophical argument.

I also wanted to talk a lot with him about his visions for how we might use genetic engineering, including existing technologies like CRISPR gene editing, to modify our bodies and modify the, you know, other organisms as well, basically to enhance our ability to handle and tolerate and even thrive in the conditions of space. So he's doing some of that work in his lab, him and his colleagues. there are others as well. So yeah, it was a really interesting glimpse into kind of what's already happening and what might happen in the future. Just one other fascinating idea that you mentioned in the book because it was mentioned to you by our mutual friend Tiffany Vora, who just became the president of Explore Mars. Congratulations. Tiffany, she's a biologist. She talked with you

about this intriguing idea of adding a brand new artificial chromosome to the human genome, which is kind of mind-blowing. Wow. It is. Yeah, I was really intrigued by that idea because I hadn't heard it before. So yeah, there's, you know, a lot of, I think people are uncomfortable with the idea of modifying human genes, and I can understand why they might be concerned about it. But if the idea is that we need to make changes to our bodies, to our genes, but that we don't want to tamper with our existing genomes, then perhaps what we could do is leave our genomes intact, but just augment them,

add an additional chromosome or set of chromosomes that have genes that could have other capabilities. And that would, in theory, allow us to have those capabilities without tampering with our genomes as they currently exist. There are some other, as I get at, into in the book some other, you know, possible consequences of that. But, you know, it is a really intriguing idea. And, and I was, you know, I was so glad that Tiffany mentioned it to me because I hadn't heard anybody else talk about it. And there are remarkable parallels here to the fictional,

the science fiction novella by Becky Chambers that we featured in the book club two months ago called to be taught, if fortunate, where she has astronauts who go on. interstellar journeys and actually are modified as they get from one star to another to not entirely, not in a huge way, but to be better able to deal with the planet that they are being sent out to do biological research on. How would you like to do field research on Mars, Scott? Yeah, well, you know, as we talked about before, I'm somebody who's always been fascinated by by nature and science and loves going places and exploring. So I would love to as long as I know I get to come back.

I'm not ready to go and sign up to be living in a Mars settlement just yet. But yeah, if I had a chance to go there and explore and do some science in the process, hey, sign me up. Same here. And you told me that your sons, your two sons, feel very much like my grandson, that they see our future in space and on Mars. as simply a part of humanity's natural advancement. Yeah, it's been really interesting talking with my kids about this.

You know, as I've been researching the book, they've, you know, heard more than their fair share of dinner conversations about, about Mars and, you know, evolution. And they got to, you know, my two youngest got to go watch the Starship launch. And my daughter also, who's 16, she's also heard more than her fair share. But I actually love using them as a sounding board, right? Because in some ways, you know, they think about this from a very different perspective than I do, right? The idea of having, you know, people living in space. To me, I always, as we talked about before, thought of that as being science fiction. But I think the idea has become much more mainstream today.

And so to them, they're like, well, yeah, I mean, that's a thing that people talk about. This is not like a foreign concept to them. And maybe somewhat affected by the fact that I'm their dad. but, you know, it is very interesting hearing their perspectives. And I always love to kind of, you know, bring myself back to reality by after going out and talking with all these amazing scientists and astronauts and coming home and talking with my kids and hearing what they have to say about it. Scott Solomon, the author of Becoming Martian. If you have not read it or if you have read it and you skip the notes section at the end of the book, I recommend reading it. you'll read all kinds of other interesting comments there. I love footnotes. I mean, one thing that I found

was about this company, Martian Garden, which will sell you Mars Regolith Simulant, and you can try to make your own garden, hopefully without any perchlorate, but absolutely fascinating. So thank you for that. Thank you for this great conversation, Scott, and for this terrific book. Well, thank you so much, Matt, it's been such an honor and a privilege to get to talk about it with you. Thanks for joining us for the Planetary Radio Book Club edition. Join me again next month when we'll head for low Earth orbit with Leroy Chow, NASA astronaut, spacewalker, and commander of the International Space Station. He has written Dinner with an Astronaut serving space stories, past, present, and future.

It's quite a feast. In the meantime, check back for the next regular episode. of the show, along with our monthly Space Policy Edition. It won't protect you from radiation on Mars, but a Planetary radio t-shirt over your spacesuit would be cool.

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