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Caleb Scharf, "The Giant Leap: Why Space Is the Next Frontier in the Evolution of Life" (Hachette UK, 2025)
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- [00:01]
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- [00:48]
Caleb Scharf
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- [01:31]
Gregory McNiff
Welcome to the New Books Network welcome to the New Books Network. I'm your host Gregory McNiff and I'm thrilled to be joined by Caleb Sharp, the author of the Giant Leap. While space is the next frontier in the evolution of life, the book was published by Basic Books in the United States in October of 2025. Caleb Sharp received the 2022 Carl Sagan Medal while Director of Astrobiology at Columbia University and is currently the Senior Scientist for astrobiology at NASA's Ames Research Center. He has written several previous trade books and is a frequent contributor to Scientific American and Nautilus Magazine. He divides his time between Silicon Valley and New York City. I selected the Giant Leap because it reimagined space exploration as a biological and evolutionary turning point where humanity's drive to overcome gravity becomes an act of thought itself to figures like Darwin, the Noether, and Tsiokovsky. And I'll ask Callum to help me with that pronunciation. Caleb Schwarf traces how the fabric of ideas and physics and morality, from energy conservation to Delta V to interacting with other life forms, will shape our journey into space. For anyone who's ever looked up at the night sky and wondered what it means for our species to leave home, this is the book for you. Hello, Caleb. Thank you for joining me today to discuss your book. Hi.
- [02:50]
Caleb Scharf
What a pleasure to talk to you, Greg.
- [02:52]
Gregory McNiff
Caleb, why did you write the Giant Leap and who is the target reader?
- [02:56]
Caleb Scharf
Well, the Giant Leap really came out of a mixture of things. My own personal fascination with space exploration. I think that's an enthusiasm I've had for a very, very long time, from a kid to an adult. But it also came out of sense that there's so much happening in space now. The pace of our access to space is increasing exponentially, with rocketry developments and launches happening. Sort of getting to the point where there'll be a rocket launch from the Earth every single day that's coming in the near future. But most of us are oblivious to what's going on above our heads and what's been going on really since. Since the Apollo era. I think the Apollo era was the last time, in the late 1960s, early 1970s, when the idea of space exploration was firmly on almost everyone's radar. Right. It was splashed across the newspapers. It had our attention for a while. And I wanted to really look at the story of space exploration and place it in a context which I hadn't seen before, which is the context of, you know, this is a moment of transition for us as a species, but also for life on Earth. After 4 billion years, life on Earth has found this way of removing itself from its point of origin and going out into the universe. What does that mean and how has it happened and how is it happening? Because there are so many fascinating stories built into this. So the whole idea of the book was to try to do it justice, try to tell that story from a slightly different perspective as well, and to project into the future all of this has been happening. It impacts us in ways that we're perhaps not aware of, and it's going to continue to impact us. And what does that mean for the future?
- [05:01]
Gregory McNiff
Wow. You touched on a number of great themes that are introduced and explored on in the book, and I want to get into that. But just to set the groundwork for the structure of the book, you introduced Darwin and the Beagle as sort of a prototype for space exploration. You write, the Voyage of the Beagle has more than a passing similarity to the complicated history and future of space exploration. Why do you make that connection?
- [05:29]
Caleb Scharf
Yeah, so when you construct a book, you obviously look for rails to guide people along.
- [05:37]
Gregory McNiff
And.
- [05:37]
Caleb Scharf
And as I was thinking about the history of exploration before space exploration, something that kept coming up for me was this story of Darwin's voyage on the Beagle. This is in the 1830s, when he was a young man, before he became old and bearded and grumpy looking the way we often remember him in photographs. And it was really a wonderful example of an extremely sophisticated type of exploration that involved a planetary journey. It didn't leave the confines of the Earth, but it certainly took in the entirety of the globe. It took place over multiple years. It took a total of five years. And the ship itself has many parallels to how we construct modern spacecraft in terms of the attention to detail, the engineering. The Beagle was a modified warship, but it was modified in really interesting ways. It was modified so that it had copper plating to direct lightning strikes around its structure. It had means of navigation. It carried 22 chronometers in order to let it navigate, to let it determine its longitude. And that alone was kind of a technological innovation, not just using clocks, but using clocks in multitude of clocks to make sure you captured errors and that you could be as precise as possible. And then even the crew was this hand selected set of people, each with a specialization, each with a particular set of knowledge, each sort of integrated into this machine that was going to go out and explore the world. So that was part of the reason for why the story of Darwin on the Beagle seemed to resonate with the idea of how do you do exploration, what is necessary, the extremes of technology that are required even on the Earth. And of course, then later in space, but then at a sort of grander level, what happened as a consequence of the voyage of the Beagle and Darwin's experiences? Well, those experiences fed into his later work on the origins of the species and his development of a theory of evolution that helped explain where everything came from and why you see the diversity of life that you do. And what's so extraordinary about that is that it in turn affected our evolution. So those ideas that exposition of a theory of evolution changed how we think about the world. It changed our understanding of species, it changed our understanding of the things that we farm or harvest to eat. It changed how we think about processes of feedback and adaptation in the world. And all of those things over time fundamentally changed the nature, not just of our existence, but through us, really, the existence of other life on the planet. It Even feeds into the sort of conceptual pieces of computer science that have given rise to modern AI. This idea of feedback induced adaptation is how we have AI, that self program. So I felt there was something really powerful in that story that relates directly to the story of space exploration, because space exploration involves these highly sophisticated forms of technology, but it also is changing us. Our knowledge of the world has changed beyond all recognition because of our access to space and our ability to look back at the Earth because of what we've learned and the technology we've developed along the way. And that means that we are changing as a consequence. We don't yet see all of the outcomes of that, but it's happening. It's changed the way our societies work. It therefore changes the selection pressures, the evolutionary pressures that we face. And through us, again, everything else on the Earth experiences all the other life, all the other parts of the biosphere. So I felt there was the Darwin story, the voyage on the Beagle was a neat analog to the story of space exploration, a way to put everything in greater perspective as well.
- [10:23]
Gregory McNiff
Yeah, I think you do a really nice job. And as I said, it's sort of a constant. I thought of it almost as like the Virgil guiding us through space exploration or the roadmap. You do a really nice job bringing it back. In each chapter, even you have some commentary on the captain, Captain FitzRoy and his approaches and Darwin's, I would say, recollections or first impressions of encountering different cultures and, you know, candidly, even his emotional response to returning home, which isn't what you would expect. So it was quite insightful and poignant in some ways. And you do a really nice job there, I should say for the reader. Each chapter begins with a quote from Darwin. So it is a constant, I think, very helpful theme throughout the book. When I asked you who you first wrote the book, you cited the 4 billion years of Earth's life or history. And in the book, in the beginning you say, listen, throughout that 4 billion years we face some extinction events. And you suggest at some point, and maybe it's now, we're looking for cosmic salvation. Could you comment on what you mean by that?
- [11:27]
Caleb Scharf
Well, sorry, I was trying to be poetic.
- [11:30]
Gregory McNiff
No, you know something we don't also working for NASA. Feel free.
- [11:35]
Caleb Scharf
I wish I did know something you don't, but no. So I think, yeah, it was at the beginning of the book. I'm trying to lay the groundwork for how we think about space, our emotional connection to our place in the universe, but then pointing out that the truth is life is fragile. Not just moment by moment, but in the long term. Life on Earth has a finite amount of time ahead of it, partly because of changes that will happen to the Earth. The sun, as it evolves, gets brighter and brighter, more luminous. So the Earth will heat up inevitably and that will change the conditions on the surface of the planet. In a billion years, the Earth may not be particularly habitable. Then further down the line, the sun will undergo even more extreme changes and probably destroy the Earth. Now, of course, that's a long way off, but we know that there are many other things that can happen. We've had mass extinctions in the history of life on Earth. Things like asteroids can hit the planet and perturb it. And so I was really reflecting on those facts, but also I think our sense of fragility. We can strut around and feel confident sometimes, but you know, we can also be reflective and consider our fragility. And one of those times is when you look up at the night sky and you get a sense of the enormity of the cosmos around you. The thousands of other stars that you can see in the sky and the millions and billions that your eye isn't sensitive enough to see. And it feels that on the one hand that's awe inspiring and overwhelming, but also perhaps there's some hope there that we're not just necessarily stuck here, that there are other potential futures for us. And maybe those futures are away from the Earth in our solar system or even further afield. So I was trying to touch on some of those quite deep, almost emotional responses that we have to the nature of existence when we have a moment to reflect on it and say that yeah, it can be daunting, but there may also be hope in the fact that there is a cosmos around us and places to go.
- [14:07]
Gregory McNiff
I want to just push or follow up on that notion of reflective theme. Again, you write the history of space exploration was never just mechanical how to do it, but a long germinating agent in the human psyche does that. Is that getting to what you're talking about? That we've always had this notion of getting beyond the bounds of Earth. How do you think about like the emotional or I guess the intellectual notion of space exploration in the human psyche?
- [14:35]
Caleb Scharf
Yeah, well, I think it's, it's connected to several things that, that germinating seed in our psyche. It's, it's the, you know, the questioning what's over the horizon, the capacity we have to understand that there may be something over the horizon of Course, for a long time, people imagined it was, you know, the edge of the world and, you know, demons and gods and what have you bordering us. But the fact that we could even make that conceptual jump, that there might be an edge to things, there might be other places beyond what we see and experience every day, I is part of it because it feeds our natural curiosity. I mean, humans are a curious species. We wonder about things, we imagine things. And at the same time, I think that germinating seed, or that long germinating seed is to do with our urge to see patterns in the world, our urge to see patterns in nature, to make sense of those. And I'm sure there are good evolutionary reasons why that's a strong trait to have. It helps you fix things, it helps you survive. But it's that urge to see patterns in the world that leads us to why do things fall instead of just stay hovering in the air when we let go of them? When I throw something, why does it follow the path that it follows? And those recognition of these patterns has led us to understand the nature of gravity, the nature of motion. Even for 2000 years plus in the Western world, we've had ideas about the nature of motion that are attempts to rationalize and place into a logical framework things that happen in the world around us. And all of those things lead to point in history, I think, where a species like us is going to not only recognize the nature of the greater universe around it, but start to agitate about how it can access that greater universe. It seems to be so intrinsic to our nature. So that's an elaboration of what I was trying to get at with that phrase. This didn't just pop up at some point in the 1940s or 1950s. It's, oh, we can go to space. Oh, that's interesting. Oh, we have rockets, and so on. That was a culmination of a long simmering set of ideas and desires and motivations to expand our understanding of the world, but to also learn how to actually access things that were previously inaccessible. And you could do that sort of randomly, by sort of somehow without much thought, building some explosive rocket device. And perhaps you succeed at getting into space and so on. But it's much, much easier if you have an understanding of the principles behind that. And that enables you to plan and to design and to test and to verify and to do this more and more efficiently.
- [17:55]
Gregory McNiff
Yep, I absolutely want to get into that. You do a very nice job of talking about the evolution of space exploration, particularly in the 20th century. And the mathematical, physics, chemistry, chemistry behind that. However, I want to talk about this key theme of dispersal that you introduce early in the book and continue to expand and develop even towards the end. And I'll just read you three small passages where you reference it. You talk about dispersal in the context of a major evolutionary tipping point, where it is a fundamental change in the possibilities of horted life. And in other contexts, you write a species launching the space passes through a new kind of evolutionary bottleneck. And then towards the end of your book you conclude dispersal is a synthesis of space exploration, the architecture of the solar system and malleable nature of evolution itself, all projected into the future. What is this idea of dispersal?
- [18:48]
Caleb Scharf
Well, it sounds very grand when you read it back to me. You pulled me. Yeah, so again it, it came out of thinking about one of the conceits of the book is this idea that learning to access the universe around us, learning about space exploration, is a pivot point in evolution. First time in 4 billion years life has had this capacity to intentionally remove itself from its point of origin. And so I started thinking about what the longer term implications of that would be and in fact, what the implications already are. And the word that seemed to fit the best was dispersal. And so dispersal is about dispersing life, like us, out into the universe, but also dispersing the things that we build out into the universe. And of course, at the moment we've done more of the latter and we've dispersed these complex spacecraft full of technology and engineering and data out into the solar system. There are things scattered across different planets and in orbits around the sun at the moment, and of course around the Earth there are thousands and thousands of artificial satellites. But dispersal of life is interesting when it's on this sort of scale, on the scale of the solar system, because as I talk about in the book, it suggests a couple of things. One is the dilution of a species. A species like us would become extremely diluted across the enormous volume of the solar system were it to spread further. That's interesting because of what it might do to us. We see parallels again on the Earth in places like the Galapagos islands, which of course Darwin visited and puzzled over. And there you had these relatively young volcanic islands that were populated by species that sort of were similar to each other and similar to species from elsewhere on the planet, but they were also different. And this was a real puzzle for someone like Darwin. And part of the answer to that is that it may have been the same species, the ancestors of what you saw were single species scattered across these different islands. But then they speciated, they evolved according to the particular conditions they found themselves in. So I think dispersal in our solar system for life, for technology, for our social structures, for everything could mean a dilution and diversification of life on a scale that hasn't happened in a very long time because of, of the scale of space and time that the solar system presents. But to understand that, you have to understand the landscape of the solar system. And so that's partly why in the book I also build the chapters around different locations or different phenomena in the solar system to try to understand that landscape, because that's the landscape on which this dispersal will happen or could happen in the future. So yeah, it's an ambitious idea.
- [22:22]
Gregory McNiff
It's definitely a fascinating one. Now I want to turn to the reference you made earlier about exploding rockets. Obviously to lever just requires a certain amount of know how, particularly technical knowledge. And I'm going to read your what you've got. It's a great description here. Rocketry to get off a planetary surface is akin to asking an over caffeinated monster to balance perfectly on one toe while hurling thousands of axes at a small imaginary target, all while on the back of a speeding truck that is plunging off a cliff. It looks majestic and easy only when all those things are under firm control. Great analogy. And your book goes into a lot of lovely and I should take several detail for how this is done. The immediate and obvious limitation is gravity. You write in a very real sense, the ultimate evolutionary trait for overcoming gravity barrier is thought itself. Caleb, have we evolved to the point where we're able to do this and how did we get here?
- [23:23]
Caleb Scharf
An obvious kind of question. If you step back and look at the history of life on Earth, the history of exploration by humans and so on, you ask, well, why did it take 4 billion years for life to crack the code of getting off of its planetary surface? And I think we're all pretty familiar with the fact that I can go out and jump up and down, but I'm not going to get very far. And it's interesting if you sort of dissect that a little bit more. It gives some clues as to why it has taken so long for life to do this and why it was human thought and technological know how that really sort of broke through the barrier. And it really comes down to a question of energetics and power. So life on Earth is remarkably energy efficient and frugal. You know, individual organisms operate on a pretty, pretty modest power budget. In general, you know, a typical human is of the order of 100 watts of power, which is energy flowing per unit time. And that's a reasonable amount of power, but it's not that much. And it turns out to be very, very different than the level of power that is required if you want to take an object, lift it off the surface of a planet, and either send it off into the universe or have it go into an orbit around a planet like the Earth. The power required, and particularly the power density. So the amount of power you can bring to focus on a small volume. So an object like a human or even a spaceship is a relatively small thing. That power density far exceeds anything that happens in biology. You can look at whales, you can look at ants, you can look at bacteria, and they all operate on a much, much lower power level and lower power density. So something had to happen to catalyze that concentration of power in such a way that it can be used to create the momentum you need to push something at greater and greater speeds until that something can essentially climb out of the gravity well of a planet. And that something, that catalyst, I would argue, was human thought and our ability to decode the mathematics of gravity, of motion, and to then implement a plan in technology using, in our case, the fact that we'd already learned to do things like explosions with chemicals. We understood chemistry to some degree, and that enabled us to find a way to generate enough power density to make meaningful progress on lifting things off the planet. So it's kind of interesting that life, at least here on the Earth, evolved to be very frugal in its energy, which makes lots of sense, right? Evolution optimizes things. When did making plans get this complicated?
- [26:48]
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Caleb Scharf
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- [27:05]
Caleb Scharf
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- [27:08]
Gregory McNiff
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- [27:42]
Caleb Scharf
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- [28:10]
Gregory McNiff
Yeah, I found that interesting, what you just said, that comparison, I guess this concept of density of energy, a biological approach versus space exploration approach. Very interesting there. You talked about effectively standing on the shoulders of the people who have helped us with space exploration going back to the time of Newton, Leibniz, and you talk about three or four individuals who we might not be familiar with. I wouldn't expect you going to too much depth on the math and the biology, but could you briefly touch on and I'll name them Emily du Chatelet, Mary Somerville, and then Emmy Noether, who we might be more familiar with, given her relationship with Einstein.
- [28:54]
Caleb Scharf
Yes. So when you tell these historical stories, the background of this germinating seed of thought that has led, I would argue, to space exploration, the different ways of doing it. And I decided when I was writing the book that I wanted to spice things up a little bit, because we've all read about Newton and Leibniz and Laplace and Legendre and the usual suspects, and there's good reason for that, because they were critical pieces of developing the theories of physics and mathematics that were necessary to do all of this. But many, many other people played a role too. And I got interested in the role of these three women separated in time across roughly three centuries. And each of them really helped further the ideas that people like Newton and Laplace and Legendre came up with and helped really distill and synthesize those ideas so that they could be applied. Newton was known for being pretty indecipherable in some of his writing and work. Even his form of the calculus that he developed was much harder to conceptualize than the version of calculus that someone like Leibniz developed. It was just Newton's way of doing things. It worked and it was brilliant. But it was also really hard going for most mathematicians of the time and most natural philosophers at the time. So you had people like Emily du Chatelet who helped both translate his work into a language like French, which meant there was much greater access for other scientists in Europe at the time. But she really also helped think about what it implied. And she thought about things like the nature of energy, which really hadn't been considered before. And energy is also related to this idea of momentum. Momentum is the product of mass and velocity, and it's just this quantity that seems to be conserved or preserved over time in a system, no matter what happens. But then this idea of energy was very new. And even Newton didn't really articulate a concept of energy. And energy is about the amount of change that takes place in the world. It's not a thing per se. It's a way to characterize and quantify the nature of change in the world. So she played a role in thinking about that and bringing that to people's attention in the scientific community of the time. And then you had someone like Mary Somerville, who came along later, who also worked on sort of distilling and synthesizing the mathematics and workings of other people like Legendre and Laplace and so on, but did it brilliantly, and thought about things like conservation of energy and momentum, and thought about things like the principle of least action, which is why things tend to slide down a slope in a straight line rather than some complicated curve. And then you had Emmy Noether, who was a mathematician and a truly brilliant mathematician, who really took this further and showed that all of these ideas of energy, momentum, of conservation of those properties in the world were linked to deep, deep principles of the physical universe, to do with symmetries, to do with the fact that sort of physics today is the same as physics tomorrow, as far as we know. And she actually put that in mathematical form as a mathematical proof that the conservation of energy is to do with the invariance of things over time. The rules today are the same as the rules tomorrow. And the conservation of momentum is to do with the fact that it doesn't matter whether something is over there or in another part of the world, it still has the same properties of motion. So all of this really put the seal on, I think, the confidence our species had that we were onto things about the functioning, the deep functioning of the universe that we could rely on, that we could use to design and build rockets and go to space, go to the moon and so on. So, yeah, three very, very interesting and extraordinary people who, I felt it was worth saying a little bit of their story in the book.
- [33:40]
Gregory McNiff
No, absolutely. It was great to read about them. I do want to turn to a fourth individual, and I mentioned him in my introduction. And again, please help me with the pronunciation here, Konstantin Tieskowski. And in fact, I mentioned you quote Darwin at the beginning of each chapter, but the quote at the beginning of the book is from this individual. Earth is the cradle of humanity, but one cannot live in a cradle forever. Great quote. And in addition to offering that insight, you note that he actually lays the gromle that is at the very heart of the physics of rocket propulsion, which I believe we term reactive flying machines. How important was this individual's insight to get us off the ground and navigate?
- [34:22]
Caleb Scharf
Tsiolkovsky was just this extraordinary and strange individual. He was Russian. He didn't have a formal education in the way that we would think about it today, but he was an incredibly precocious child. And so he did get tutored. This is in the late 1800s into the early 1900s. And he kind of worked on his own volition on these. These problems of what lies beyond the Earth, the nature of orbits, which were well understood at that time. And he was very motivated to think about how we would. How our species could access space, how a species could, you know, move along these orbits around the Earth, how our species could inhabit other worlds, build structures out in space like space stations. He was just this font of innovative thinking that eventually people in the west discovered, unfortunately, as he was getting pretty old. But his work was discovered, and it played a central role in informing scientists in the west, but also scientists back in Russia and the Soviet Union, of fundamental principles of things like rocketry. And so he thought about, how do you generate propulsion that can accelerate you enough to overcome the barrier of gravity to put you into space, to get you moving quickly enough to orbit the planet, which is very fast indeed. You have to typical orbit around the Earth at low altitude is around 8 kilometers a second, which is really, really fast. It's like 20,000 miles an hour or something like that. And so he produced a number of works on this, mathematical works, and including one where he talks about sort of principle of reactive machines. And really, the idea of rocketry, which he saw and developed, and we now all follow, is that it comes back to Newton's idea of for every action, there's an equal and opposite reaction. So if you're sitting out in space and you throw something away from yourself, you throw that object, you give it momentum, but in order to balance out that momentum, you will gain momentum yourself in the opposite direction. We've all sort of experienced this at various points. If you throw something, you kind of have to sort of steady yourself as you throw an object, because there is a reactive force pushing you back as you give a force to throw an object away from you. And so Tiolkovsky's insight was, yeah, a rocket or A reactive machine has to essentially just throw mass in one direction away from itself, and that will accelerate it in the opposite direction. And he worked out the mathematics of what happens when you throw a certain amount of mass out the back of your rocket and with what speed you throw that out, and what does that gain you in terms of your forward motion, in terms of your acceleration. And he constructed this famous equation that's now become known as the rocket equation, which basically tells you what you gain by expelling a certain amount of stuff with your rocket, depending on how fast you can expel it. And, of course, most rockets try to expel stuff very fast. We've all seen rockets, video of rockets being launched, and material is churning out of the back of them at high speed. And that rocket equation is critical for computing how much fuel you need, how much propellant you need in order to accelerate a given mass of spacecraft to a certain final velocity. The sad thing is, and various people have talked about this, and there's a famous quote by an astronaut, I think it's Don Petit, who said the tyranny of the rocket equation and the tyranny of the rocket equation is that there's a diminishing gain for having more propellant to throw out the back of your rocket, because you have to actually bring that propellant along with you. So before you can throw it out the back and get the benefit of that propellant to accelerate you, you also have to accelerate the propellant because it's part of your rocket. And it turns out there's diminishing returns. And essentially you could build bigger and bigger rockets, but actually, it's really hard to go faster and faster and faster with these sorts of conventional chemical rockets. Tsiolkovsky was really the first person to point that out, but also to point out the practicalities of rocketry, among many, many other things. I mean, he thought of the idea of spaceships. He thought of space stations. He thought of the idea of airlocks. He thought of all kinds of stuff far ahead of his time.
- [39:37]
Gregory McNiff
Yeah, he was truly just a fascinating individual. I want to just expand on what you said later on in the book you write about delta V, this change in velocity being the currency of space exploration. Can you expand on that?
- [39:52]
Caleb Scharf
Yeah. So this is quite a technical thing, and I think for people not familiar with space exploration or space flight, it can seem kind of strange. So delta V refers to a change in velocity. So V stands for velocity. And it turns out that if you're out in space, let's say you're in an orbit, and you want to change that orbit in some way. Maybe you want to make it a larger orbit, a smaller orbit, or change the shape of the orbit. Could be a circular orbit, could be an elliptical orbit. The best and easiest way to think about making that change is think in terms of how much you need to change your velocity. Do you need to increase it by a certain amount? Do you need to decrease it by a certain amount? But to change your velocity means firing up your rockets or doing something else to accelerate yourself for a period of time or decelerate yourself. And that requires energy. That takes fuel or it takes some other method to accelerate or decelerate yourself. And so the shorthand that is most useful in thinking about astrodynamics and rocketry is this quantity of delta V. Instead of talking about the actual amount of energy, talk about the end product. You want to achieve a certain change of velocity. There are many different ways you might do that. And so people talk about delta V for that reason. It's a simplifying notation, if you will. But it also turns out to let you talk about sort of schemes and strategies for getting from one point in space to another point in space. So if you want to go from orbiting the Earth to go and orbit Mars, you can actually talk about a sequence of changes in delta V or delta V that you need to make in order to do that. And you can actually map out the delta V that is required and the points in your journey at which you need to create that delta V. And you can even make almost like a subway map for the solar system because the orbits of the planets are pretty much fixed. And so you're trying to get. If you're visiting planets, you're trying to get from planet A to planet B. And you can actually calculate what the minimum and maximum amounts of delta V are in order to do that. So it's kind of a. It's a very technical term, but it's sort of appealing because it. I think it's. Most of us can grasp it to some degree and it sounds cool to talk about delta V. You know, you're a rocket scientist if you're talking about.
- [42:36]
Gregory McNiff
Delta V. No, it's cool reading about it. At one point you say rocketry is basically high stakes plumbing. That might be a little obviously tongue in cheek, but it's clear, you know, I think you do a nice job of conveying these concepts and how they have to deal with it. I want to. Want to ask you about one more before we move on. And that is The Oberth effect, if I'm saying that right, what is that? Why did it sort of initially, I think, had people a little perplexed. And yet to some extent, it's very simple. Once you understand it.
- [43:06]
Caleb Scharf
The Oberth effect is really interesting. And it's still, I think, even causes professional physicists to pause for a moment when it's brought up for them. So the Oberth effect was this discovery or recognition by a scientist. I believe his first name was Herman Oberth in the early 1900s. And what he realized was that if you look at the equation that describes the energy of motion of an object. So this is what we call the kinetic energy. That kinetic energy is the product of the mass of an object by its velocity squared times a half. The half is there for various reasons that one doesn't have to worry about. So the energy of motion of an object is proportional to the square of its velocity. And that's kind of interesting because it means that you can more easily change the energy of an object when you're moving faster. And so the faster moving an object is, the easier it is when you turn on your rockets to actually modify the energy of motion, the kinetic energy, which is very strange and counterintuitive. Right. You would think, oh, it's easier to change something if it's stationary. Right. I turn on my rocket, of course, I accelerate, and I'm gaining energy. But actually, you gain energy more efficiently the faster you're moving for the same amount of propulsion, which is very bizarre. But it is just how the universe is constructed. And what's so important about the Oberth effect for space exploration is it does tell you exactly when you should turn on your rockets, if you want to maneuver, if you want to change your orbit, if you want to get into orbit around another planet. It's not when you're moving the slowest that you get the most bang for the buck. It's actually when you're moving the fastest. So you want to modify your orbit. For example, if you're in an elliptical orbit, there's a point in an elliptical orbit where you're moving the fastest, and then you slow down at the far point. In an elliptical orbit, well, it's actually when you're moving the fastest where you're going to get the best outcome by switching on your rockets for a moment, trying to change your Delta V to go back to what we were just talking about. So it's this very strange yet extremely simple phenomena that I think, for most of us, very counterintuitive. But it's just there in the equation. And Oberth was clear minded enough to see this and say, oh well, yeah, this is what we should bear in mind if we're traveling around in space, that when you're moving the fastest, you actually get the most change in your energy of motion for the least effort.
- [46:09]
Gregory McNiff
Yeah, it's fascinating the way you describe it now and in the book. And you do make the point that at some point when we begin to understand the mathematics of space travel, that was a real inflection point or stepwise function. And I think that example you just gave is exhibit A in that thesis. I want to move on now. We talk about how sort of intellectually you thought about space exploration structure of the book, starting with Earth and then moving outwards. I don't think this will surprise anyone. The first way stop would be the Moon. What would surprise people is that you actually refer to the Moon as Earth's last and least explored wilderness. Could you clarify that?
- [46:49]
Caleb Scharf
Well, this is because the Moon is really part of us. One of the most remarkable things that we've learned over the last several decades is a picture of how the Moon came to be. And so the current best model of this, and it's backed up by the data of samples that the Apollo astronauts brought back from other data that we've obtained. Thinking about origins of the Earth itself and so on. Our best picture of where the Moon came from is that it kind of came from us. So that sometime four and a half billion years ago or so close to the point which the Earth itself formed, we think that another protoplanet, an object, possibly even the size of Mars, essentially collided with the Earth as it had formed up to that point. And that collision resulted in a mixing of those two bodies, of all the material of those two bodies, but then also a sort of reformation of both objects. So a reformation of the Earth and a reformation or a new formation of this satellite of the Earth, the Moon. And because of that collision, everything got mixed together. And so really the Moon, as far as we can tell at this point, is as much a mix of what we are as we are of it. And that's very different than, for example, Mars. Mars almost certainly formed in a different part of the solar system out of a slightly different mixture of material four and a half billion years ago. Whereas the Earth and the Moon are essentially two pieces of the debris of this enormous collision that took place four and a half billion years ago. So that's why I refer to the Moon as really our last great wilderness, because it's almost identical in terms of its composition to the Earth. And it's been hanging there in our skies certainly for as long as humans have been around and really for as long as life has been on. On Earth. So it's rather wonderful to think that, yeah, there's this other landmass, if you will, that sort of lurks 250,000 miles from us and is really pristine. I mean, yes, we've landed a few spacecraft, we've left some detritus from our astronaut visits and so on, but it is this extraordinary, pristine wilderness that is part of us. It's part of our. You know, I wouldn't call it a national park because that would be too skewed to, you know, the United States. But it's. It's a world park, if you will.
- [49:45]
Gregory McNiff
Very nice. And you make that point very well in the book. And yet you also say lunar space is more complicated than near Earth space. Why is that? And what are the challenges to overcoming those complications?
- [50:00]
Caleb Scharf
This really gets into the details of the internal structure of the Moon and the nature of gravity in a complicated system where you have a planet with a moon around it and different gravitational forces pulling in different directions as those objects orbit around each other. So one of the discoveries during the Apollo missions was that the Moon is kind of lumpy inside, much lumpier than the Earth is. We've all, I think, in our school days have seen these pictures of a cross section cutting through the interior of the Earth or other planets. And it all looks very sort of orderly. It's like these onion layers. There's an Earth's core, there's a mantle, there's a crust. And the same for other places like Mars and the Moon and salt. But in reality, an object like the Moon has sort of lumps inside of it that are different density. And so its gravitational field is actually not entirely uniform. And so the Apollo astronauts discovered this, or some of the experiments that they left in lunar orbit began to reveal this because the orbits of those objects were not that stable. And it was because rather than orbiting around with a perfectly constant force of gravity on them, they're orbiting around with an undulating gravitational force from the Moon. And that destabilizes orbits or can destabilize orbits. So, in fact, around the Moon, there are only a couple of orbital orientations which are pretty stable. And these are for orbits that are kind of close into the Moon. But those are the useful orbits. Either if you're exploring the Moon or trying to study it, you want to be reasonably close and that's different than the Earth. The Earth has a smoother interior distribution of mass. It's easier to place an object around the Earth and put it in orbit, and it will just stay there if it's not too impacted by the Earth's outer atmosphere. So the Moon is interesting that it's. There are a couple of so called frozen orbits where if you place a satellite around the Moon, it will pretty much stay in that orbit. But everywhere else, if you place a satellite over time, it will destabilize. Now that sort of can seem a bit like an esoteric quirk. Who cares? But if we're really serious about going back to the Moon, about creating a more permanent presence at the Moon, about studying the Moon in more detail, and if there are geopolitical motivations for claiming parts of the Moon or parts of lunar space, this becomes challenging because there are these few orbital zones that are very much preferred and they're limited in scope. So there's sort of a, you know, you can imagine a, I hesitate to say a fight, but a competition over lunar space that is different than what we have around the Earth.
- [53:13]
Gregory McNiff
Yeah, that definitely I could see that transpiring. That will be interesting, if not concerning. One cool aspect you discussed is the fact that the Earth's magnetosphere is actually, Caleb, jump in here. Seeding the Moon with oxygen atoms. I literally had to reread that paragraph again and go, am I understanding this right? Oxygen to the Earth is blowing up. I know, I'm not using NASA terminology when I say that. Could you please explain how that's possible? And that, yes, there are atoms of oxygen from Earth on the Moon.
- [53:50]
Caleb Scharf
Sure. So, you know, and this is our current understanding. So, you know, stuff can change as we learn more. So the Earth's magnetic field is reasonably strong and it interacts with the flow of material coming from the sun, the solar wind. And that's been well known and well understood for a long time. But that flow of solar wind distorts the shape of the Earth's outer magnetic field out in space. And it also means that material flows along magnetic field lines in almost like a teardrop shape around the Earth as it goes around the Sun. And it turns out that every month or so, there's roughly four days in every month as the Moon is orbiting the Earth, which takes a month. Right. That's our definition of a month. The Moon kind of passes through a part of Earth's, this extended magnetosphere, this zone of the magnetic field, diverting the solar wind and particles flowing along these Magnetic field lines, and they sort of wash across the near side of the Moon. It's kind of like a garden hose, right? Roughly four days every month. But the really interesting thing is that the Earth's atmosphere, as it gets very thin up towards the top of the Earth's atmosphere, in so called exosphere, atoms and molecules from the Earth's atmosphere can get caught up in this flow of material and sort of channeled through our magnetosphere in this teardrop shape and essentially blown on to the surface of the Moon and implanted there. So it looks like this is based on real data taken by a variety of spacecraft and analysis of lunar soil and so on, that atoms of, for example, oxygen from the top of the Earth's atmosphere, stuff that kind of filters up there do get blown away by the solar wind and end up implanting on the lunar surface. So, okay, that's really interesting, right? And that means two things, though, if you extrapolate what that means. First of all, it means that in some ways there's a, there's a recording of the contents of Earth's atmosphere on the near side of the Moon, because this must have been going on for a very, very long time, for millions, if not billions of years. So that's really interesting. And maybe we can learn something about the evolution of the Earth's atmosphere once we get back to the Moon and can better analyze the lunar soils into which these terrestrial atoms of oxygen and hydrogen and other things have been implanted. But then the other piece of this that's truly mind blowing and bizarre is that we know that water ice does exist in deeply shadowed places on the surface of the Moon. So in particular, the polar regions of the Moon, like the southern polar region of the Moon, there are these deep craters that never receive direct sunlight. And we've used radar and a number of other methods to determine that there is water ice sitting there at the lunar surface in these shadowed craters. Now, that's really interesting because water ice is a potential resource for exploration. You can turn it into hydrogen and you can turn it into oxygen, which we can breathe. But you can also make rocket fuel out of hydrogen and oxygen. And of course, humans need to drink water. So, you know, going and landing near the water ice is, is ideal for exploration. But it's possible that some of that water ice, perhaps most of it, is actually formed using the oxygen atoms that came from the Earth's atmosphere in the first place. And where do those oxygen atoms come from? Where they come from life. They come from photosynthetic life on The Earth that evolved some two and a half billion years ago. So there's something really fascinating and strange about that, that life may have inadvertently produced a resource for its future exploration of the Moon.
- [58:10]
Gregory McNiff
Yeah, that is truly astounding. I don't know if that's like interplanetary evolution or just, I don't know what.
- [58:16]
Caleb Scharf
You would call it.
- [58:20]
Gregory McNiff
We talked about the Moon. I want to keep moving out. The next planet you discuss is Mars. And you lay out the sort of three current scenarios of explore Mars, terraform, populate Mars or Earth First, I. E. The resources we better spent on improving our planet. You suggest a force option that, quote, melds our talent for observation and computation with our messy biology. Could you briefly talk on your. Your approach to how we should think about exploring Mars?
- [58:50]
Caleb Scharf
Right. So my approach tries to sort of dance between these other ideologies about exploring Mars and you mentioned them briefly. One is a sort of pure, pure science exploration where we're extremely cautious about how we explore because we don't want to contaminate things. One is the gung ho, let's put a million people on Mars and settle it. And then the third one is we shouldn't be expending anything on this when we have so many problems back on Earth. My take on this, my fourth way is to exploit what we already know how to do, and that is to characterize Mars in a way that we've only just begun to characterize it. And so this is using satellites, using robots, using our ability to generate data and to analyze that data, to essentially build a sort of digitized version of a planet in a way that we have been doing for the Earth, but we've only been doing it sort of more recently and sort of retroactively. Mars is a place where we could change the rules of exploration dramatically because I think we still think about exploration in the well, we must go and set down somewhere and walk around and poke at things. We could do a lot better than that. We don't need to do it the way that Darwin did it on the Beagle anymore, where they didn't know what they were looking at. They had to go and map things. They had to dig out their telescopes and their sextants and make measurements constantly and deal with bewildering circumstances. Mars. What's so interesting is we could make Mars a truly connected world with minimal human presence. We probably would want some human presence, but that human presence would benefit enormously by showing up on a world where there's already cell phone service, there's already A GPS service. There's already all the things that we utilized to great effect here on the Earth. This fourth way dances somewhere between the three extremes. Because the gains of this. If you're an Earth firster and you say, well, none of this has any value. Well, actually, learning about the functioning of an entirely different planet in intimate detail, its climate state, its history, its chemistry, the way things are modified when we go and explore other worlds tells us a huge amount about the fundamental principles that apply also to the Earth that we're still figuring out, still decoding. Principles of climate, principles of geochemistry, principles of how life interacts with an environment, and salt. We have this one experiment on the Earth. We have the potential to have at least a partial experiment on another world that could be incredibly informative. It would also lay the groundwork if we wanted to eventually have more humans there. And it would also satisfy much of our scientific curiosity. So it's not a truly radical, different approach, but I think it's a more realistic approach that says, look, there are things we know how to do really well, like our, you know, connected Earth. Right. We can connect Mars up before we actually really try to put people there or explore it in a more sort of casual way. But there are enormous benefits to doing that. The technology that we would develop and what we would learn about another world.
- [62:41]
Gregory McNiff
Yeah, absolutely. Fascinating discussion. And you later on the book talk about Jupiter, Saturn, Titan, forcing us to work on our machines in new ways if we consider exploring them. And then you say, with regards to these other planets, testing our technologies and skills helps define what we call the boundary conditions of a zone of easiest exploration for our species. I think that touches on what you just said. But could you. Could you maybe clarify what you mean by, quote, easiest exploration for our species?
- [63:11]
Caleb Scharf
Yeah, it does. It does relate to what we just talked about. So the idea here was. And this really is an idea that actually comes out of my own scientific research, I study astrobiology. And in astrobiology, we're very concerned with concepts such as the habitable zones of a planetary system. And what that means is the places in a planetary system where we think life has the most chance of existing, if it's an alien planetary system, for example. And that idea of a habitable zone is to do with limits of temperature for life. It's to do with stability for life and so on. But it occurred to me in writing the book that if we're talking about life that leaves its point of origin, it may go to places that are not traditionally habitable. And it May go to places that are more or less easy to explore. And that sort of limits of exploration become important as much as the limits of life. And so the zones of easiest exploration, your own solar system, Are kind of scouting out or sketching out where does it make the most sense to put our energies into in terms of exploring. So we know that somewhere like the planet Mercury is super interesting, but it's also incredibly difficult to explore because it's that much closer to the sun, to the point where you run the risk of essentially melting your spacecraft. And equally, as you go further and further out in the solar system, what becomes challenging is a lack of sunlight. So solar power becomes less and less useful, but also communications become more and more challenging because of time delay of the light travel time. And so I wanted to at least put that idea out there, that part of our future is in understanding where we can most easily explore in our solar system. And it's not as obvious as just distance from the sun. It's more complicated than that. It's to do with, for example, around Jupiter. Jupiter generates an enormous magnetic field that creates an intense radiation environment around itself. So it's actually very inhospitable, for the most part, to be anywhere near to Jupiter. But there are interesting places to visit there, you know, icy moons that might have interior oceans and salt. So we have to start thinking about, you know, the zones of easiest exploration, because that will help define things like dispersal. Where are the most likely places that we'll end up in our solar system? And what does that mean? And what are the implications right now for how we do things?
- [66:06]
Gregory McNiff
Yeah, that is, again, fascinating answer. And particularly that notion of getting the highest bang for our buck or being thoughtful or strategic about how we approach space exploration. And to that point, pretty much towards the end of the book, you sort of lay out your thesis or your view that the real challenge is for us to imagine a solar system so differently configured with life and all its supporting structures on such a scale. And you introduce this concept of an interplanetary transport network. What is that?
- [66:38]
Caleb Scharf
Well, so it's not my idea, I'll be clear about that, but it's a really interesting type of. It's a concept that I think modifies our perception of what it means to move around in our solar system, what it means to potentially live beyond the earth. So the interplanetary transport network comes out of quite esoteric mathematics that study the nature of orbits. So we're very used to thinking about the sort of colloquial way of thinking about Orbits is. Well, it's a path around the sun or it's the path of the Moon around the Earth. It's either it's a circle or it's ellipse. It's kind of these fixed things. And to a large extent, that's true. And in many instances, yes, an orbit is pretty much a fixed thing, and it's a closed loop. But it turns out that when you have multiple massive objects in a system such as we do in our solar system with planets and moons, there are these places where the gravitational pull of different objects can sort of balance out. It's also complicated by the fact that everything is in motion. All of these planets are themselves orbiting. So if you want to orbit the planets, you have to take into account the planets orbit around the sun or Moon's orbit around its planet and so on. And it turns out that mathematically, there are these zones. You can almost think of them as tubes in space. I mean, they're not really tubes, but conceptually, you can kind of think of this network of tubes that are places where orbits are kind of unstable. So one way to think about it, suppose I. I orbit further and further away from the Earth. At some point, I'll orbit far enough away from the Earth that the gravitational pull of the Moon will start to dominate my motion. And so I might now fall towards the Moon and start orbiting the Moon. But that point of transition, that sort of point of balance between the Earth and the Moon is kind of interesting because if I sit there, it doesn't take much effort to move myself one way or the other. I could choose to fall to the Moon. I could choose to fall to the Earth. And so the interplanetary network is really a mathematical description of these complicated places like that, where it doesn't take much effort to kind of drift along. Another way to think about it is imagine a sort of hilly landscape. And I've got some, you know, car with big, big wheels on it. And it kind of rolls around in that landscape. Well, you know, if I'm careful, I don't have to push the accelerator very often because I can sort of push myself just over a hill. Then I'll roll down the other side and I'll coast partway up the next hill on that. On that motion, on that energy. And these. The interplanetary network is kind of like that. It's these places where you can drift a spacecraft with very little propulsion. And as long as you're patient, you can eventually transport yourself from one place in the solar system to another. The downside is it can take a long time because you're not necessarily moving very quickly. You're sort of finding those places in this hilly landscape where with minimal effort you could just push yourself across the next hill or down the next valley. And it turns out that with computers we can calculate aspects of this interplanetary transport network. And you can, with very little expenditure of energy of propulsion, take a spacecraft from the Earth. You could take it all the way to Mars, you could take it all the way to Jupiter. You can move it around the solar system without much effort. It just takes a long time. But imagine a future where we're dispersed across the solar system. We're making use of the enormous resources of the solar system, which far outweigh and outnumber anything we have on the Earth. You may not care too much if it takes a long time for something to reach you. It's been following this low energy transport network, orbital network, through the solar system and so on. So it changes how we think about sort of existing in a planetary system because it changes the pace of things. It's actually more akin to drifting across an ocean on a sailing ship, where you're just kind of catching the breeze here and there to keep moving. So I thought it was an interesting piece of sort of non intuitive orbital mechanics that might be relevant for the future.
- [71:43]
Gregory McNiff
Absolutely. I mean, I think like you said, we almost optimize for time traveled or distance, and that's obviously key, but energy expended ultimately is the way it seems like the overarching key metric. And you do such a nice job of building up to that, laying out the thesis. Before I ask you the final question, I do want to ask you one more. How cool is this? And for the reader, you introduce so many cool concepts. Kessler events, ion drives, gravity assist, stellar weather, determining how we build spacecraft. But again, the one I was like, yep, got to read this again, is these Lagrange points, It just, it feels like this oasis in a desert that almost goes back to what you just saying, helps us, you know, limit or manage our energy efficiency. Could, could you explain even concept? Yeah, yeah.
- [72:35]
Caleb Scharf
So Lagrange points, they're very much related to what I was just talking about, these sorts of points where you can ease yourself through this gravitational landscape. Yeah. So Lagrange points, they're places of sort of quasi stability. So around, for example, the Earth and the moon, there are five so called Lagrange point. So there's a point not exactly midway between the Earth and the Moon where essentially the gravitational pull of the Earth and the Moon, plus the rotational centrifugal forces of the orbit of the Moon around the Earth balance out. And that's called the L1 point, the Lagrange point one. And so if you place something there, it will for a while, because it's not a particularly stable location, but it will for a while track precisely the line joining the Earth to the Moon, which is kind of strange because at that distance from the Earth, it ought to be orbiting at a different speed. But because the Moon is there, it sort of reduces the effective pull on that object that it experiences from the Earth. And so it sort of stays in sync with that line joining the Earth and the Moon. And then there's Another point, the L2 point, which is on the opposite side of the Moon from the Earth, which is the same. And that's a little bit more interesting. If you place an object there, it will also track exactly a line joining the Earth to the Moon. So it's an interesting place to put a spacecraft because it will always be on the far side of the Moon from our perspective and actually out of sight from the Earth. But then there are these other points. There's a point on the opposite side of the earth called the L3 point. And then there are these points along the orbit of the Moon, but separated from the moon by about 60 degrees of the arc of the Moon's orbit around the earth, called the L3 and L, sorry, the L4 and the L5 point, Lagrange 4 and Lagrange 5 point point, those are comparatively stable. And so both natural material will tend to accumulate around those points. And you can also put a spacecraft there and it will sort of sit there and kind of stay close to that, that point. But what's really bizarre about these Lagrange points, and they exist because of this balance of forces between the gravitational forces of two objects and the fact that they're in motion around each other. So you also get a set of these points around any pair of objects you can think of in the solar system. So the Earth and the sun, for example. And in fact, we make use of some of those Earth Sun Lagrange points, like the so called L2 point of the Earth's sun, which is on the opposite side of the Earth from the sun always. And it tracks that point. That is where we've placed instruments like the James Webb Space Telescope. And it's because it's a nice safe place, it's far enough away from the Earth that it doesn't disturb the telescope. But we can also keep the telescope there by expending very little energy. It's in actually what's called a halo orbit, so actually orbits nothing. It sort of circles around that Lagrange point too perpetually with a little push now and then from its thrusters. But it's a relatively stable place in space and it's a useful place to put some of our spacecraft. So yeah, it's a difficult concept because it's this actually quite complicated balance of gravitational forces and to do with the rotating reference frame of orbiting planets. But we've discovered these things mathematically and then we've gone and found that yeah, they work right. We could put spacecraft there and we see places in the solar system where material accumulates around these sort of balance points. So there's a rich unseen structure to the gravitational landscape of our solar system that as we become better and better space explorers, we're going to get more and more used to and it's very strange, quite alien.
- [77:03]
Gregory McNiff
Yeah, that, that really was just again another incredible moment of you know, math and space exploration and you know, cool concepts driving our, driving our progress in this area. Before I get to my last question, I will say you do a really nice job talking about early space exploration on both the American and Soviet side. Our readers. Absolutely worth reading. It's just fascinating how both of those programs were built. Neil Armstrong suit alone, everything that went into it. And again we're talking, you know, 1950s, 1960s shout out to everyone else involved, everyone involved in that given the limitations of technology relative to today. So that's also a great part. Unfortunately we didn't get time to touch on last question. Caleb, do you think the Giant Leap will be viewed in a similar fashion, namely a prophetic vision by future generations as Hedward Hale's 1969 novella the Brick Moon, which presaged GPS, you know, over 160 years ago or close to. Do you think maybe 150, 160 years from now people will be looking back at your book and going, wow, everyone thought he was nuts at that time, that this guy was really on to something.
- [78:11]
Caleb Scharf
Well that would be lovely, wouldn't it? I, I, you know, I don't know, I, I, I, I feel, you know, maybe it's the, the Brit in me that I'm self deprecating. I'm not sure I've, you know, managed to say anything super new, but I think it's about sort of seeing the connections between these different aspects of something like space exploration. I would hope that What I've done is tried to steer a line between the truly fantastical and hypothetical, which is so easy to do when you're writing about this stuff. It's easier to get carried away and say, oh, we're going to build this, we're going to do that, and so on. What I've tried to do is point to what I think is a realistic picture of how things will play out, where the possibilities lie and what that future looks like. So, yeah, it would be lovely. I mean, the brick moon that you mentioned is an extraordinary story. I think it was written in 1869 by Edward Hale and it was a sort of serialized novella where he basically. Yeah, he talks about building an artificial satellite. It's a brick moon. It's about 200ft across for navigational purposes. But then he foresees things like in the story, he has one of the characters observing people on this brick moon who've been inadvertently carried along with it when it was launched. And he talks about seeing them making these enormous bounds because of the lower gravity on the brick moon. And that, of course, is exactly what we all saw with the Apollo astronauts or astronauts on space stations and thought. But to make that conceptual jump was just brilliant because it was spot on. So I would hope that I managed to replicate some of that informed speculation, informed extrapolation. Yeah, if I do as well as Edward Hale did in that story, I'll be very, very happy.
- [80:15]
Gregory McNiff
No, I suspect you will. I mean, again, the book is sobering. Many times I'm like, wow, it's amazing what we've accomplished. And by the same token, you lay out the obstacles we still need to overcome, including our own biology, which we really didn't touch on here. But wonderful read. That concludes our interview. Again, the book is the Giant Leap, why Space Is the Next Frontier in the Evolution of Life by Caleb Scharf. Caleb, thank you so much for your time in writing such a thought provoking and fascinating book. It was truly a blast to our audience members. Please go out and buy it. I am going to go out and buy some rocket lab stock. And thank you again, Caleb.
- [80:55]
Caleb Scharf
My pleasure. Great to talk to you.
- [80:56]
Gregory McNiff
Likewise. And Doug, here we have the Limu Emu in its natural habitat helping people customize their car insurance and save hundreds with Liberty Mutual. Fascinating. It's accompanied by his natural ally, Doug Limu. Is that guy with the binoculars watching us?
- [81:30]
Caleb Scharf
Us?
- [81:30]
Gregory McNiff
Cut the camera. They see us.
- [81:31]
Caleb Scharf
Only pay for what you need@liberty mutual.com savings. Very underwritten by Liberty Mutual Insurance Company and affiliates. Excludes Massachusetts.