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The Giant Leap
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In this conversation, Dr. Caleb Scharf discusses the evolution of space exploration, drawing parallels to historical figures like Darwin. He explores the implications of humanity's expansion into space, the challenges of microgravity, and the allure of Mars as a potential habitat. Scharf emphasizes the interconnectedness of space exploration with our daily lives and the future of humanity as a dispersed entity across the solar system.
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Takeaways
- Humanity's move into space is a new phase of evolution.
- Space exploration is a continuation of life's four billion year experiment.
- Microgravity affects human physiology in profound ways.
- Mars presents both challenges and opportunities for human exploration.
- Lagrange points offer stable locations for spacecraft in orbit.
- The moon's composition is closely related to Earth's.
- Understanding space exploration is crucial for our future as a species.
Chapters
- 00:00 The Concept of Dispersal in Space Exploration
- 04:54 The Universe's Self-Awareness and Its Implications
- 08:32 Darwin's Influence on Space Exploration
- 14:14 Historical Figures in Science and Their Impact
- 21:59 The Moon Landing: A Complicated History
- 28:14 Challenges in Spacecraft Navigation
- 30:13 Effects of Microgravity on Humans and Animals
- 33:50 The Drive for Interplanetary Exploration
- 36:39 Understanding Lagrange Points
- 42:06 Life on Other Planets: Mars and Beyond
- 48:40 The Future of Humanity in Space
- 54:41 The Essence of Curiosity
- 54:57 Embracing the Unknown
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Transcript
Exploring Math and Storytelling
00:00:00
Speaker
Hey, everyone. Before we get started today, i have a huge announcement to make. This Saturday, October 25th at 2.30 p.m. Eastern Standard Time, many of the authors from the show, some new faces and i are teaming up with the Fields Institute for Writing Math.
00:00:16
Speaker
It's a live session all about how math meets storytelling. It's a live If you've ever wondered how to market yourself to a broader audience, talk about complicated math to anyone, or how to capture an audience without losing your readers, this event is for you.
00:00:32
Speaker
It's free to join both in person and online, and you'll find the registration link in the show notes. So come hang out with us and learn how to make math sound as beautiful as it truly is. And if you're still wondering if this is going to be for me, because I'm not a mathematician, it is You already listen to the show regularly. This time, you get to ask the guests questions about their work live.
00:00:57
Speaker
Also, you can email me questions that you may have as well. So go sign up and hang out with us. We can't wait to see you there.
Humanity's Evolution into Space
00:01:05
Speaker
Every so often, humanity does something that feels less like invention and more like instinct.
00:01:11
Speaker
We build rockets, hurl ourselves into the void, and call it exploration. But maybe, as Dr. Caleb Scharf, astrobiologist and author who works at NASA suggests, it's really biology and we're doing what we've always done, spreading, adapting, and reaching out for what's next.
00:01:32
Speaker
In his book, The Giant Leap, Scharf argues that when we leave the Earth, it's not just humans stepping off the planet, but it's life itself continuing its 4 billion year experiment.
00:01:45
Speaker
So welcome to another episode of Breaking Math. I'm your host, Autumn Finaf. And we're asking, what if the cosmos isn't something we explore, but something that's exploring itself through us?
00:01:58
Speaker
Caleb, your book opens with a bold premise that humanity's move into space isn't just an adventure, but it's a new phase of evolution. You describe it as almost as a cosmological event. So Let's start here.
00:02:14
Speaker
What inspired the term dispersal? And you frame humanity's push into space as not just an exploration, but as a continuation of life's
Dispersal and Speciation in Space
00:02:24
Speaker
evolutionary story. It sounds very grand when you say it like that.
00:02:26
Speaker
Yeah, so... You know, the the idea behind dispersal is that when we try to make projections about the future, and it's obviously extremely challenging. So what are the things that are given if, for example, our current efforts at space exploration continue to grow and accelerate, which is what's happening right now? Things are accelerating all the time.
00:02:49
Speaker
We're heading towards a point where there'll be a rocket launch every single day of every year into into either orbit around the Earth or further afield. So, yeah know, what's the extrapolation from that? And dispersal is the idea that a species like us, along with organisms that will carry along with us on our journey, will move into a landscape that it hasn't experienced before.
00:03:12
Speaker
So life on a planet can feel spacious, sometimes kind of sparse. If you go to the deserts or Antarctica on Earth, it can feel like life is is very sparse and and spread thinly.
00:03:25
Speaker
But that's nothing compared to the landscape of our solar system. Solar system is a a vast place in space and to some extent in time because of the finite speed of light and how signals take time to cross that that space and so on.
00:03:41
Speaker
So dispersal is really a statement about sort of a condition that will face a species that becomes truly um you like well a true space explorer and spreads itself, which is ah ah a process of dilution and diversification, to put it in simple terms.
00:04:01
Speaker
So the idea of dispersal is there is so much space There are so many resources in our solar system that a species that continues to advance its exploration, continues to advance its movement away from its point of origin on a planet, is going to become extraordinarily diluted and dispersed. And that dilution and dispersal may result in new things happening to that species that are almost beyond its control.
00:04:26
Speaker
So, for instance, on the Earth, we know that if a species populates new environments, over time it likely changes, it speciates, it goes from being one species to many different species. And the dispersal is about that process as well, that The future of humanity, and this is not, you know, in the next decade or the next century.
00:04:47
Speaker
This could be much, much further down the timeline. And the future of humanity, the future of our species, is actually a dispersed entity that turns into many new species. So the future of us out in the solar system is not going to be really be us.
00:05:03
Speaker
It will be descendant species. It will be greater diversity. will be species that are more isolated from meet each other because of the nature of the scale of the solar system.
00:05:13
Speaker
And so the idea came out of really trying to articulate what the what the options are for a spacefaring species. So as we're looking at different species, we also look at the fact that the universe is becoming aware of itself.
Universe's Self-Awareness and Evolution
00:05:28
Speaker
What does that mean in concrete scientific terms?
00:05:32
Speaker
And why does that matter? So this this this term that people do use, which is that the and universe is becoming aware of itself, is really about the observation that if the universe began and the Big Bang 13.7 billion years ago, it had very little structure.
00:05:50
Speaker
ah Matter was dispersed in unstructured form. There were no dimensions. complex molecules, there were no complex structures. It was all kind of uniform and boring and mostly hydrogen and helium. And it took at least the first billion years before heavier elements were formed in the interior of stars. Those stars formed because of gravity.
00:06:11
Speaker
Gravity pulled together matter where it was a little uneven in the early universe and eventually the universe starts to build more and more complex structures. Now, that itself is a bit of a mystery.
00:06:24
Speaker
Why does the universe do that? And we can talk about things like the growth of entropy and thermodynamics, but the the emergence of complexity is still a bit of a puzzle.
00:06:35
Speaker
And then the really extraordinary thing is that at some point, Certainly here in this one place in the entire universe on the earth, we know that sufficiently complex structures formed that were able to encode in themselves information about the external world and to process that information in order to take actions that further increase their chance of surviving into the future.
00:07:01
Speaker
That's part of what we call life. And so, know, we perhaps... live at a special time in the history of the universe, at least you know from our perspective, where this emergence of awareness of structures complex enough to decode what's around them, to actually, or rather, encode in themselves information from the surrounding universe, whether it's in symbolic representations or presumably in biological organisms, it sort of part of the encoding in their DNA and the expression of of genes is related to what surrounds an organism.
00:07:36
Speaker
And so that awareness of the universe becomes a factor in the future evolution of a structure of an organism. And so It's kind of remarkable that we, perhaps it's not so surprising that we're sitting here thinking about this because we're at a point of time in the universe where this is possible, at least here. And it may have been possible much earlier in the history of the universe, but we don't know that for sure.
00:08:00
Speaker
And that plays into many, many aspects of change in the universe. are Self-aware organisms, organisms that can decode the environment around them and take action on that information, necessarily alters the environments themselves.
00:08:19
Speaker
And of course, life on Earth has been continually sculpting and re-sculpting the nature of the environment and that it finds itself in. i think it's particularly interesting to think about that in the context of our space exploration.
00:08:33
Speaker
We've now got to a point where our encoding of information about the universe, our awareness the universe, and of course we are of the universe, so we don't sit outside of the universe, has taken us to a point where we're incorporating information from not just the earth, not just what's immediately around us, but further and further out into the cosmos. And that is driving new change in our environment and therefore in us.
00:09:00
Speaker
So that's maybe a partial answer to your question. Is the change really going to be more biological than technological? think that's an open question. It's a really interesting question.
00:09:13
Speaker
So humans and other species do this to some extent. You know, you can look at other species and say, well, they have sort of technology. I mean, ah you know, a bunch of termites that build an elaborate nest with ventilation systems and so on. That's a form of technology, one could argue. But humans do this to much greater extent, it appears, than any other species on the Earth. We express our ideas in structures around us.
00:09:40
Speaker
We build things that modify the environment for us. And space exploration right now is kind of the the premium example of that.
00:09:50
Speaker
So, i yeah, i think I think you've put your finger on something really important, that life beyond a planetary origin for biological organisms may inevitably be life plus technology.
Darwin's Voyage and Space Exploration
00:10:01
Speaker
You know, it's not like I could drop down on the surface of Mars without space suit, without any anything and survive. You know, I'd last about 30 seconds, something like that.
00:10:12
Speaker
And so the future is is more likely to be an increasingly intertwined system of technology and biology as we move away from the Earth. So let's step back in time a little bit here because you discussed the historical inspiration of Darwin and the Beagle in your book.
00:10:35
Speaker
Do you want to go into that a little bit so you can see how the evolution of what Darwin talks about and how space exploration is being discovered today and the parallels between it? Sure. Yeah. So as I so worked on this book and and researched how to tell the story of space exploration, became clearer and clearer to me that one has to look at it through the lens of natural history. Space exploration, I think, is is it's a phenomenon. It's something that's emerged out of us as a species, and it's best understood. Its implications, its past, its present, and its future, its implications are best understood yeah as a form of natural history.
00:11:16
Speaker
And so It made sense to look for parallels in the past to the current enterprise of space exploration and the consequences of that. And it became clear to me that Darwin's experience, and and particularly his voyage on the Beagle, so this was this journey on a sailing ship built by the British Empire in the eighteen thirty s the early 1830s, when Darwin was a young man, he was in his early This was a famous voyage that literally went around the planet.
00:11:48
Speaker
It was a planetary expedition for five years. And there there are parallels that are somewhat mundane and trivial, but interesting. And then there are parallels that are much deeper to do with this idea of evolution that, of course, in part, emerged from that voyage. So the...
00:12:05
Speaker
The more sort of straightforward parallels are when you look at an expedition like the Voyage of the Beagle, you realize that it had many, many similarities to space exploration.
00:12:16
Speaker
You had this vessel, this craft. It was an extremely carefully constructed craft. It had been customized and modified regularly. to encounter sort of unknown environments as it went around the world.
00:12:29
Speaker
It had the latest technology on it. This was something I hadn't really understood, but the ship was before its voyage that took Darwin. It was modified to make it resilient against things like lightning. It had metal plating on it.
00:12:44
Speaker
They swapped out the iron cannons on it for bronze or brass cannons because those would influence the compasses they had on the ship less because it would change the interaction with the Earth's magnetic field.
00:12:56
Speaker
They had 22 chronometers on the ship in order to keep track of time because time was key for navigation. you knew the time relative to some datum, you could always figure out your longitude.
00:13:10
Speaker
But they didn't want to rely on just one clock. They had 22 clocks to test and keep track of. So it was this remarkably sophisticated technological vessel that that also had a very sophisticated crew.
00:13:22
Speaker
It had specialists, it had people who were handpicked to serve a certain purpose. So all of it looks like modern space exploration, but, you know, ah hunt more than 100 years earlier.
00:13:35
Speaker
But the more profound piece of this was when you look at what happened during that voyage. So that voyage enabled someone like Darwin to be exposed to a remarkable amount of information about the world, to things he'd never imagined before, to living systems he'd never encountered before, and so on.
00:13:55
Speaker
And so that sort of overview effect of the Earth played a role in his later work on the origin of species and the development of a theory of evolution, the development of a theory of natural selection and its implications for the change in organisms over time.
00:14:13
Speaker
And That work, Darwin's eventual work, which in part was catalyzed by the Voyage of the Beagle, actually changed us as a species. mean, this is the irony, I think, of his work on evolution. His theory of evolution caused evolution in us and through us in all of life on the planet.
00:14:33
Speaker
And it did that because it changed our approach to evolution. things like how we grow and breed our food stuff, how we engage with other species on the planet, whether it's plant life or animal life, and the ways we think about processes like feedback and change in the world. These were all profoundly impacted by Darwin's theory of evolution. And I argue that space exploration is doing the same.
00:14:58
Speaker
And it's So there's ah there's a really great lesson to be learned from Darwin and the Voyage of the Beagle, both to do with the technicalities of exploration, but also to do with what changes in the world when you move beyond ah familiar, ah when you learn more about your own planet,
00:15:18
Speaker
Of course, space exploration has done that for us Satellites now sense and image the planet on a daily basis, and that's fundamentally altered our relationship to the planet. But course, we learn about other places, and it creates new possibilities for life in orbit around the Earth and further afield.
00:15:36
Speaker
So that's a rather long-winded response to your question, but it's... That's okay. Yeah. It's a deep connection. It's a thorough, thorough answer because you went into the history of this quite a bit. And I'll say history repeats itself. Absolutely. And you also go into ah Emily Duchelet and some of the other scientists that that are that throughout history whether it's been Laplace, Lagrange, all the way up to Einstein and Newton and how they change the world and all of the universe's meanings right do you have a favorite story or two that you want to highlight especially it's such a long evolution Yeah.
00:16:23
Speaker
Yeah. So part of what I wanted to explore in the book as part of this sort of natural history of space exploration is to ask the the question, so why hasn't this happened before? Why has it taken 4 billion years for a species to figure out how to intentionally remove itself from its point of origin?
Intellectual Breakthroughs in Space Exploration
00:16:41
Speaker
by lifting off the surface of the planet. And some of the the explanation for that is just energetics. It's that power density in biology is very different than what you need to accelerate matter or objects to the point where they can be in a sustained orbit around a planet and so on.
00:17:00
Speaker
What I realized in thinking about that was that it took human thought to make that breakthrough. You know, it wasn't a biological trait in terms of, you know, growing an extra pair of wings or somehow developing a ah propulsion system like, you know, the way that aquatic, some aquatic animals propel themselves around by squirting water. Those weren't the things that allowed us into space. What allowed us into space was human thought.
00:17:27
Speaker
And you mentioned a um number of the characters in that in that story. yes And to me, i i wanted to find new voices to tell that story. We've all heard of Newton, right? And we may have heard of Laplace and Lagrange and Sainz and Leibniz and all of these people who are engaged in sort of some of the frontier pioneer work.
00:17:50
Speaker
But the truth is, it always takes more than a few key figures to make a profound change in human thought. In this case, it would lay the groundwork for space exploration, you know, 400, 300 years later.
00:18:04
Speaker
And so some of those stories were really interesting. And I picked, in particular, three really extraordinary women who played a role across about three to four centuries in this story. and So you mentioned Emily du Chรขtelet. So she came around not too long after Newton. She was essentially a French aristocrat of a sort.
00:18:26
Speaker
She was also this remarkably bright and energetic person. She she was married, but she also had ah sort of lifelong um affair with Voltaire, just to give you a little snippet of, you know, the colourfulness of her life.
00:18:41
Speaker
She was pretty good at gambling, apparently. She was, ah you know, she enjoyed life, but she was also a remarkable intellect. And one of the things she did was help translate Newton's works into French, which ah gave access to entire sort of network of French philosophers and natural scientists in a way that wouldn't have happened without her.
00:19:04
Speaker
And not only that, she helped push along these ideas about concepts such as energy. And energy is a really weird concept because it's not a thing per se.
00:19:16
Speaker
And we often get trapped in in that, you know, the science fiction stories, you know, Star Trek. It's a being of pure energy. Well, this' that doesn't make sense. Energy is a characterization of the world that expresses something about how things can change in the world.
00:19:32
Speaker
ah You need energy for things to change. Duchatelet... kind got to grips with this in a way that hadn't happened before. And so she was this catalytic phenomenon.
00:19:43
Speaker
And so I wanted to tell that story because it was so interesting and her life was so extraordinary. She died tragically young because of childbirth, which obviously was pretty perilous in those times. But she she injected ah huge amount into um the development of Physics, the development of ideas around things like energy and movement, the laws of motion, all of which laid groundwork for eventually space exploration.
00:20:11
Speaker
But then there are other people like Mary Somerville, who came somewhat later than Duchatelet, and Somerville was an extraordinary ah mathematician who also worked on really decoding some of these very...
00:20:26
Speaker
oh very esoteric and hard to um hard to pass um mathematical frameworks that people like Legendre and Laplace had formulated. But she was able to you know further develop those frameworks. And so she studied things like the principle of least action, which is a central principle that kind of tells you why if you you roll down a hill, you roll in a straight line usually. and You don't take some meandering path.
00:20:56
Speaker
You will take the shortest path between two points. And that is also an extremely important concept for when we're thinking about movement in space, in orbits, and so on.
00:21:07
Speaker
And she also helped sort of work out the mathematics that would allow us to make predictions about the orbits of planets. And she was someone one who... you know had been married off at an early age, but then, i guess lucky for her, the husband died early age, leaving her with time on her hands and some money in the bank, and she was able to pursue her interests. And then you get to, in the early 20th, people like Emmy Notham, who was one of the most brilliant mathematicians of the early 20th century, even Einstein agreed on that fact.
00:21:43
Speaker
And she took ideas like energy and momentum and the fact that those quantities tend to be conserved in the universe. So a system, you can evaluate the momentum of a system, which is the product of the mass and the velocity of objects.
00:21:59
Speaker
And what you find is that in general, momentum is conserved or preserved through time. Things can change if you have ah a pool table and the balls bouncing off each other.
00:22:10
Speaker
It looks like things are changing, but the total momentum of all those balls tends to be conserved. It tends to be the same sum total over time, which is kind of strange. But Nother took this step back into very abstract mathematics and proved that the conservation of things like energy and momentum, which are so important for understanding rocketry and space travel,
00:22:32
Speaker
ah You know, the conservation of those quantities is a result of deep fundamental symmetries in nature. The fact that physics today is the same as physics tomorrow, as far as we know, gives so far rise to things like the conservation of energy.
00:22:49
Speaker
And the conservation momentum comes from the fact that something is the same when it's placed over here as it is when it's placed over there. These sound almost too simplistic, but they're actually really important fundamental theorems that she was able to prove.
00:23:04
Speaker
So anyway, so, you know, what's interesting about their stories is that they really lay out this progression in human thought that all the pieces were falling into place for that step of application into taking us from the surface of the planet out in into the universe. So let's shift a little bit as we're going out into the universe.
00:23:31
Speaker
July 20th, 1969. We ended on the moon.
00:23:35
Speaker
we ended up on the moon was our first lunar landing. And it was 71 attempts before that. And many of the attempts, it was the big space race against the Soviets.
00:23:49
Speaker
And granted, they might have landed before that, but there were some crashes. Definitely. So, yes the lack of readily stable low orbits around the moon can be a spaceflight headache, but it's also a direct window to a complicated and violent history that is also connected with Earth.
00:24:13
Speaker
Tell us more about that. This is a big story. So one of the things that came out all of the Apollo missions and some of the other lunar exploration, as you say, there were a lot of attempts and a lot of things didn't work and a lot of attempted robotic landings on the moon and so on.
00:24:29
Speaker
But one of one of the experiments that the Apollo astronauts took part in wasn't actually on the lunar surface. It was in orbit. So before some of the Apollo missions returned to the Earth, the they actually left behind in orbit these small sort of sub-satellites, these kind of suitcase-sized satellites, which is kind of interesting. It's something people aren't aware of, that they didn't just perform experiments on the surface of the moon, the astronauts, they did some of this stuff in space. And what was really intriguing was that these suitcase-sized satellites that were left, and they were left to monitor certain things like radiation and radiation,
00:25:06
Speaker
to perform some sort of simple scientific experiments long after the astronauts had left. Those satellites had a hard time staying in orbit around the moon. They were orbiting fairly close into the moon. There's no atmosphere, so you can orbit not far above the surface.
00:25:21
Speaker
But the orbit's seemed unstable. And to cut a long story short, what was realized from that and from later study, in fact, study that continues to this day, is that Moon is very lumpy and bumpy in its interior.
00:25:35
Speaker
I think, you know, in school, we all get that sort of lesson on, you know, the interior of the Earth where you have a cutaway and it looks like an onion. with different layers, there's a core, there's a mantle, there's a crust, and it's all sort of very symmetric.
00:25:49
Speaker
The truth is, an object like the Moon has enormous variations in the density of material in its interior. It's not a perfect onion. It's kind of a slightly moldy, lumpy onion inside.
00:26:01
Speaker
And those variations in density mean that its gravitational field is not perfectly symmetric. And that's what those satellites were experiencing. They were experiencing a non-uniform gravitational pull as they went around the moon. And so their orbits were not necessarily very stable.
00:26:18
Speaker
So why is the moon like this?
Origin of the Moon
00:26:20
Speaker
Well, that really was the beginning of this remarkable story of decoding the origins of the moon. And what we think is the current best picture of where the moon has come from is that it's essentially come from us.
00:26:34
Speaker
But it's more than that. It's come from... the results of an enormous collision some four and a half billion years ago between an object that was sort of proto-Earth, a planet-sized object that was the Earth before this collision, and another object that may have been the size of Mars that collided with the Earth, material from those two objects apart, then remixed it.
00:26:58
Speaker
And the Moon then formed as a satellite around the remaining proto-Earth. And as a consequence, the the material of these two earlier objects got mixed together.
00:27:08
Speaker
So in a very real sense, the moon is the last untouched piece of us. The Apollo mission also, Apollo missions and the astronauts' samples that they brought back also told us that the composition of the moon is almost identical to the composition of the Earth in terms of the rocks, the the silicates, the carbonates, and so on, and all the isotopes of the elements that you you find in those materials.
00:27:34
Speaker
which sort of further supports this this idea that we kind of formed out of the same stuff, which is really remarkable. The moon, you know, you look at the moon in the night sky and you think, well, yeah, it's beautiful, but it's this other thing, right? and We know it's quarter of a million miles away.
00:27:51
Speaker
But it really is like looking at, you know, the last great desert on Earth or the last great piece of the South Pole that's been unexplored. It's a wilderness. It's as much a part of us as we're a part of it. So it's ah it's a good story.
00:28:05
Speaker
But don't people still crash into the moon until today? There was this one story that you had. It was 2019 with Israeli mission.
00:28:18
Speaker
Yes. why Why is that? Why haven't we gotten it right right now? Because it's it's close. Yeah, no, space is hard, right? yeah So, yeah, getting spacecraft down onto the surface of another world is extremely difficult, even if it's the moon, which is relatively nearby. And i mean you already mentioned, you know, prior to the Apollo landings, there were there were many, many attempts.
00:28:43
Speaker
Back at that time and in the... 1960s into the 70s, you know, some of the challenges were things as crazy sounding as just not knowing exactly where the moon was at any given time, which may sound very bizarre. But if you think about it, how do you measure it exactly where an object quarter of a million miles away is?
00:29:05
Speaker
You can use radar, you can use, you know, telescopes and so on. But you know, Getting that, the precision of knowing exactly where the moon will be when you arrive in your spacecraft um down to, you know, hundreds of meters is difficult.
00:29:21
Speaker
And to some extent, that's still true, although we've got much, much better at that. But the truth is that the sorts of speeds and precisions required of trajectories of spacecraft to get them to a place where They can land safely on the surface of an object like the moon, not a crash, where everything happens in perfect sequence is still incredibly challenging and difficult to do. And it's because it's a mixture of electronic sensing and mechanical hardware.
00:29:51
Speaker
You have rockets and thrusters and, you know, they they can experience variations in the thrust they produce. They maybe don't switch on in exactly the millisecond that you need them to switch on. And there can always be other other factors. Some piece of the spacecraft may have shaken loose and it changes the the profile of the spacecraft and and how it responds to the thrust applied to and so on. So absolutely, yeah. So we're still crashing things on the moon um and even just within the last 12 months.
00:30:22
Speaker
been efforts in this increasing effort to have commercial providers um send um spacecraft to the moon, you know, cheaper and better.
00:30:34
Speaker
You know, that also runs into these challenges. And each attempt, you learn something, but the trouble is then you've got to do it all over again. You can't just sort of, it's not like a video game where just reset. You have to rebuild, relaunch, and go through it all again.
00:30:49
Speaker
Let's actually take a little bit of this space exploration into what happens to us, humans, animals. We've had various missions here. Essentially, everything from your heart, your eyes, you get stomach problems. We haven't even touched on microgravity.
00:31:09
Speaker
Tell us some of the effects of humans and animals going into space, just for the very basics. Yeah, well, so almost since the beginnings of putting animals into space, humans into space, perhaps the biggest difference is um an absence of gravitational acceleration when you're in an orbit or when you're floating out in the middle of nowhere.
00:31:31
Speaker
in the universe. Here on Earth, we're subject to a constant gravitational acceleration. In the space station, you're typically, you're orbiting, and that means you experience close to zero gravity, or so-called microgravity. I mean, in an orbit, there's always little deviations and changes.
00:31:50
Speaker
That has profound effects on our physiology, on human physiology, on the physiology of other creatures, even on the sort of the stress responses of microbes, everything on Earth has evolved in a gravity well under constant gravitational acceleration.
00:32:06
Speaker
So put a human in space, the first things that happen are that your body's trying to arrange the the liquids inside of itself. That starts to go wrong because there isn't a sort of uniform acceleration towards your feet. So liquids in your body will be end up in places that they're not usually. Some of that changes and sort of gets corrected as your body adapts. But astronauts talk about having sort of swollen heads and skinny feet.
00:32:34
Speaker
And it's because your body is is desperately trying to place the liquids that your blood or your lymphatic system in the right place, but it can't because there isn't gravitational acceleration.
00:32:45
Speaker
Your cardiovascular system responds and has to try to figure out what to do, how to circulate your blood efficiently, even your breathing, ah the diffusion of oxygen in the membranes in your lungs is modified.
00:32:59
Speaker
Your bone density can change quite dramatically and quite quickly in zero G. And this has been one of the The big challenges for astronauts who spend a long time in in these conditions in the space station is you'll suffer bone mass loss or bone density loss. You get osteoporosis, essentially. And that's problematic.
00:33:19
Speaker
Obviously, when you come back to Earth, you don't want to suddenly be a bag of jelly when you get out of your spacecraft. But it also causes problems for your kidneys because the the calcium in your bones leaches into your body.
00:33:32
Speaker
your blood and into your blood plasma, and then that's filtered by your your kidneys. And so you can get kidney stones because your bones are essentially dissolving inside you. And your microbiome gets strongly perturbed and disturbed. And that's something that's been studied a lot in recent years, as we've learned that the human microbiome, these all the bacteria and archaea that live in us in our digestive systems and are part of our immune response.
00:33:58
Speaker
they get stressed. So that population changes and that can cause stomach problems. There's questions about sleep. It's hard to sleep in in microgravity. Your vision can be impaired because the shape of your eyeballs can change because there isn't gravitational acceleration on your on your eyes and so on and so on and so on.
00:34:18
Speaker
i mean, it doesn't make it sound very attractive, but obviously we've also figured out ways to mitigate some of those problems. But if we're looking at not just immediate space exploration, you said even for a long term, we're thinking about exploring other worlds, other planets.
00:34:36
Speaker
We've started looking at some of these other planets since, what, 1958?
Challenges in Interplanetary Exploration
00:34:42
Speaker
ah ish when we put probes out to the moon and to Venus.
00:34:47
Speaker
But now, also with Mars in its sights, tell us about why we want why we wanted to explore all of these other planets, just not just in our solar system, but also there was some exploration for Venus in like 1962 as some of the early days.
00:35:07
Speaker
Tell us a little bit about that. Right. Well, think it's... you know part of Part of what I wanted to tell in the book is this story of the sheer amount of exploration that has taken place um since essentially 1957 and launch of Sputnik, which kind of was a sort of proof of concept project.
00:35:28
Speaker
that we could put things into space and and have them there for an extended period. You know, almost immediately after Sputnik was launched and went around the Earth, both the United States and the Soviet Union made all kinds of plans for interplanetary exploration.
00:35:44
Speaker
So the Moon was an obvious target, but then so too were Mars and Venus and, you know, There were plans afoot by the early 1960s and spacecraft being launched in attempts to reach other worlds, whether to fly past them or even eventually to go into orbit around other planets. And, you know, that had its problems.
00:36:07
Speaker
There's a famous example where the Soviets were trying to send a probe to Venus. And again, you had to to do that. You had to know where Venus would be when you arrived. right And that was challenging.
00:36:19
Speaker
The precision needed to pinpoint Venus to within even a few thousand miles is pretty pretty serious precision using Earth-based telescopes and measurements. So they were using things like planetary radar, extremely powerful radar pulses out into the solar system to get the bounce back in order to locate the planets. And there's a famous example where the Soviets, reasons that are still a little bit unclear, to mislocated Venus.
00:36:47
Speaker
Yeah. of the order of a hundred thousand miles and there's a nice sort of cold war story there where the us learnt of this and basically poked fun ah the soviet union right it was a good piece of pr yeah in the cold war by saying well Apparently, the Soviets have discovered another planet orbiting the sun, ha, ha, ha because they don't know where where Venus is.
00:37:11
Speaker
So there's some really interesting aspects to those early stories where nobody had done this before. They were hashing out the the fundamentals of space exploration. How do you find where a planet is going to be when you show up there?
00:37:23
Speaker
How do you power your spacecraft? How do you stabilize your spacecraft? How do you navigate in space? These were all things they had to do from scratch. So it's a really but interesting, interesting history.
00:37:35
Speaker
But when we're launching to these other planets, you talk about Lagrange points. What are they? Because I know some listeners, they may be going, what?
00:37:46
Speaker
What is that? And apparently in 1970s, they had a $1 billion dollar but budget for deep space exploration. Was that one of the calculations?
00:37:58
Speaker
Yeah. So, you know, so Lagrange points are an interesting phenomena and, you They're quite hard to get your head around, but they play an important role and have played an important role in space exploration because of what they provide for us, as as well as just being a natural phenomenon. So, know, we're used to thinking about gravity on the Earth, right? It's pulling us in one direction. We understand that if you move further and further away from the Earth, that gravitational pull weakens.
00:38:28
Speaker
Similarly, we're used to thinking about, well, there's the moon orbiting us and the moon is orbiting us because of the mutual gravitational pull between the Earth and the moon. and that's kind of how orbits work in some hand wavy way.
00:38:40
Speaker
But it turns out that when you look at the mathematics of objects that are, you In mutual gravitational attraction, like the Earth and the Moon, or the Earth and the Sun, or the Earth and the Sun and the Moon and all the other planets, and in constant motion in these orbits, there are these weird places, these weird points in space that they're not on the surface of a planet.
00:39:03
Speaker
or the moon, they're just out there in space, where things sort of balance out, forces kind of balance out, or at least you can sit in those places and be much less disturbed by the pull of gravity of other objects.
00:39:17
Speaker
But the locations of those places is kind of unexpected, I think, if you hadn't really thought about this. So there are these locations that lie between somewhere like the Earth and the moon,
00:39:30
Speaker
ah There's a sort of balance point. If you took a straight line journey from here to the moon, there would be a point some distance from the Earth and towards the moon where essentially you wouldn't really feel a pull one way or the other, but you would still be moving with the motion of the moon around the Earth. And it's that's what's called the L1 or Lagrange point 1. It's sort of a balance point between the Earth and the moon.
00:39:57
Speaker
That's not so hard to conceptualize because you think, well, yeah, the moon is pulling, the Earth is pulling. There'll be a point of balance where they sort of equal out. They sort of balance out and you're not going to get pulled in one direction.
00:40:10
Speaker
It's complicated by the fact that everything's in motion, that the Earth and the moon are orbiting around each other or around a common center of mass. And so that makes the calculation a little more complicated.
00:40:21
Speaker
And of course, it was Lagrange, whose name is attached to this, who really made these these computations. But it doesn't just stop there. There are other points. There's an L2 point, an L3 point, an L4 point, an L5 point, which are these locations in space around a system like the Earth and the Moon where things kind of balance out.
00:40:43
Speaker
So, for example, on the far side of the Moon, A certain distance is the so-called L2 point for the Earth and the Moon. And that also is a kind of a point of balance. You could sort of hover a spacecraft there and it will orbit in sync with the orbit of the Moon around the Earth, even though it's further away from the Earth, which is kind of strange. So you can always have the Moon between you and the Earth if you sit in that point, which may not be terribly useful, but it is...
00:41:11
Speaker
what happens. Then these other points, like the L4 and L5 points, actually sit in the same orbit as the Moon around the Earth, but ahead of the Moon and behind of the Moon in orbit by about 60 degrees of arc, if you think of a big circle um representing the orbit of the Moon.
00:41:28
Speaker
And those places are also... in sort of somewhat stable locations. In fact, the places where um natural material can accumulate over time. And we don't see too much of that in the Earth-Moon system.
00:41:41
Speaker
But the same kind of phenomena happens, for example, for Jupiter and the Sun. There are L4 and L5 Lagrange points in that system, ahead of Jupiter and behind of Jupiter.
00:41:54
Speaker
And because of the mass of Jupiter the mass of the Sun, those points actually accumulate asteroids. And so there are great groups of asteroids um ahead of ah Jupiter in its orbit and behind Jupiter in its orbit.
00:42:09
Speaker
All of which is say these balance points also are useful for us because they're places we can put spacecraft and have those spacecraft kind of sit there for a longish period of time without having to do very much. But they're not orbiting a planet.
00:42:25
Speaker
The orbiting, ah the spacecraft is essentially hovering or orbiting around an empty point in space, but it's one of these these extraordinary balance points. They're quite hard to conceptualize, but mathematically, we can work out precisely where these points are, and we can then exploit them.
00:42:42
Speaker
So, for instance, the James Webb Space Telescope sits out at the Earth-Sun Lagrange point 2, or L2 point, And it actually performs what's called a halo orbit.
00:42:53
Speaker
So the spacecraft uses its thrusters to just nudge it around that empty point in space. And it's a great place to be because it's far enough away from the Earth that the telescope isn't impacted by the Earth's infrared radiation because the telescope is optimized to look at infrared light.
00:43:11
Speaker
So that's a a little bit of a description of these these Lagrange points. And they exist across the solar system. In any place where you have a pair of objects, you get Lagrange points.
00:43:22
Speaker
Another thing that I really wanted to go into is life on other planets. whether that's in our solar system or even beyond.
00:43:32
Speaker
Now, immediately we think of life on another planet. Our thought is Mars. What is going to happen? We know that the moon is potentially for us
Mars as a Settlement Option
00:43:44
Speaker
habitable.
00:43:44
Speaker
Not saying that that's going to be the first place that we're going to look, but we're already looking at space exploration to Mars. Now, what's going to happen there? We're going to have a lot of different things that are coming about, and that includes everything from governance to supply chains.
00:44:02
Speaker
And you also mentioned that Mars may be a little bit of a siren for us. Do you want to tell us why? Because that that's a loaded question. Yeah, I mean, you know, to put it in sort of simple, quick terms, Mars has long held our attention, right? And some of this is because of misunderstandings a century ago about, you know, what was going on on Mars.
00:44:28
Speaker
We'd look at it with our telescopes and some people imagined they were seeing structures from some civilization on Mars and so on. And so we've long had in our heads that Mars is is, you know, not so different than the Earth, and it might be a good place to set up shop for for humans. The truth is Mars is extremely alien and and a very, very different world than the Earth.
00:44:50
Speaker
But it is ah sort of large planetary body and it has had a history a deep history over billions of years where it's undoubtedly been much more hospitable much more habitable where it has had liquid water on the surface and so on today it's an arid desert planet in fact a cold arid desert planet yeah and With very very little atmosphere, with sort of quite severe surface radiation, both ultraviolet radiation because of the lack of atmosphere and just cosmic radiation.
00:45:22
Speaker
The surface chemistry of Martian soil is quite caustic, contains these oxidizing compounds that are somewhat problematic. And the surface of Mars, if you're standing on the surface of Mars, you experience only a third of the gravitational acceleration that you do on the surface of the Earth.
00:45:39
Speaker
So Mars is, yet at the same time, i think we've all seen these pictures return from the surface of Mars, from rovers and other landers. And it looks kind of beautiful, right? It looks like the American Southwest. It looks like these wonderful sculpted hills and sand dunes and so on. So there's this strange thing that goes on in our brains where we sort of say, well, you know, yeah Mars seems like a good place to set up shop. and If we wanted to really experiment with with human settlement beyond the Earth.
00:46:10
Speaker
Perhaps we should go to Mars. Some people think of Mars as a place where we build a sort of backup against existential risk. You know, what if something really bad happens to the Earth? Preserve humanity and other species on Earth.
00:46:25
Speaker
We should have a backup. We should have you know, humans on a place like Mars. It's far enough away that whatever happens to the Earth, it'll it'll carry on. But the truth is, and I, you know, I call Mars the red siren because on the one hand, it feels so appealing because there are similarities. We can kind of get our heads around what it would be like to be on the surface of Mars and so on.
00:46:48
Speaker
In every other respect, though, it's ah it's an appalling place. It's probably at least as challenging as the lunar surface. to exist on Mars. We don't know what the long-term effects of things like reduced gravity are um on the human body. We've never really done that experiment.
00:47:06
Speaker
The Apollo astronauts are on the moon so briefly that it didn't really tell us anything. The radiation environment and so on and so on and so on. And the isolation the sheer distance from the Earth to Mars.
00:47:18
Speaker
So one of the things that i try to explore in the book is the the range of options available to us for a place like Mars. What do we do? What should we do?
00:47:29
Speaker
Should we study it cautiously as scientists? Should we go all in and put, you know, a million humans on the surface of Mars? Or should we leave it alone? Should we pay attention to the Earth first and and not bother about Mars. I think there's actually another approach that's a bit of a ah ah mixture of some of the things that we've become really good at.
00:47:51
Speaker
So, for example, we could make Mars the most studied and most um scrutinized planet in the solar system other than the Earth. We know how to do that.
00:48:02
Speaker
We know how to place satellites around a world and image it and sense the composition of the planet and monitor it, build communication networks, sort of digitize a world.
00:48:15
Speaker
Perhaps we should be doing that to Mars before we worry too much about sending people. We should make Mars the the most sort of digitized connected world other than the earth do that first gain understanding of the martian environment that we don't have yet and then start to think seriously about whether we put humans there but perhaps humans on mars is not really a long-term option you could do better by creating artificial habitats where you can spin them up to generate artificial gravity you can have complete control
00:48:49
Speaker
over the the environmental conditions in a way that is very challenging on another planet, on ah on a world like Mars. So, yeah, there are many questions about Mars, but I think there's a tendency to imagine that Mars is much easier than it really is.
00:49:05
Speaker
So let's look at this on a grander scale. Do you want to paint us a big picture, whether that's 500 or 5,000 years from now? And when do you think that we're going to truly take the
Future of Human Civilization in Space
00:49:20
Speaker
giant leap?
00:49:20
Speaker
I actually think we're in the very beginnings of the giant leap right now. ah We're seeing this exponential growth in the launch of rockets from the surface of the Earth. We're seeing enormous growth in sort of the early days of what I would call a space economy. There's always been a space economy to some extent since you know, the the mid middle of the last century, but it's taking on a new form.
00:49:46
Speaker
There are now across the globe something like 10,000 space-related companies operating, which is kind remarkable. We have roughly 30 locations on the surface of the Earth where launches can take place, I think we're beginning to see the first sort of nudge towards that giant leap.
00:50:06
Speaker
Where it goes, of course, is always going to be very hard to predict, but there are things that we know true. So, for example, the sheer scale of our solar system, the sheer abundance of resources means that over the next century, over the next 500 to 5,000 the impetus, the motivation to do more and more off-world, to do more and more out in the solar system, that motivation is is large.
00:50:34
Speaker
We know that there are quintillions of dollars worth of rare elements in asteroids around the solar system. That might be problematic for the Earth's economy because it would just disrupt the economy and, you know, that much platinum or gold, suddenly platinum and gold isn't worth anything anymore.
00:50:52
Speaker
But the utility of those elements and things like rare earth metals, the utility of those for building technology really comes into its own in a space-based economy, an economy that is no longer just on the earth. It's on multiple worlds. It's spread across the solar system, potentially in habitats that we construct, whether we build them out of asteroids or whether we build them entirely from scratch as artificial environments for ourselves. So I think yeah One possible future that is also arguably ah future driven by the kind of things that life does in general. Life expands. If life is presented with a new niche, it will move into it, almost regardless of whether or not we think that's a good idea.
00:51:41
Speaker
And I think we do have agency, but we also, as a species, when there are billions of us, things just happen. And it's not necessarily because of one person's decision or a group's decision. It's just there's an inevitability to some of the things that take place for us as a species. And I think space is one of those things.
00:52:00
Speaker
Hundreds of years, thousands of years into the future, what might that look like? We get back to this idea of dispersal, a dispersed humanity, dispersed civilization. There could be pockets that are very, of that civilization, very different with different social structures.
00:52:15
Speaker
But the scale of it would also imply ah difference in how industry operates, how societies operate, how we get material from one place to another in this future solar system and so on.
00:52:28
Speaker
So part of what I look at in the book are sort of the boundary conditions for this. We may not know what the details are, but we can ask what would be the ultimate extrapolation. I'll say this just because it's fun to kind of imagine this. If you actually look at the wealth of materials in asteroids and other objects scattered through solar system, there's enough stuff to build thousands of biospheres and technospheres.
00:52:54
Speaker
There's enough energy from the sun to support trillions of humans, plus all of the biospheres that would be necessary to support those um those those individuals. So the the extrapolated version of this is something completely outside of our minds.
00:53:13
Speaker
current experience ah a scale of civilization a scale of life unlike anything that has happened on the earth's surface for sure you know imagine a future with 50 trillion humans scattered across the billions of miles of the solar system sounds fantastical sounds crazy why on earth would that happen well the thing is it could happen and perhaps it will it sounds crazy it does Humanity with its current state.
00:53:40
Speaker
But I would argue that the the sheer scale of the solar system would mean that, let's say, those 50 trillion humans, then they wouldn't be squabbling over all the same stuff.
00:53:52
Speaker
They might be squabbling amongst themselves, but they would be so diluted and dispersed around the solar system that, you know, at least somewhere there would probably be a functional society. It might not be everywhere, but there would be at least one place where things would would function.
00:54:06
Speaker
Yes. Out of curiosity, is there anything that you want folks to take away from this conversation or even about space in general? I guess the biggest thing I'd like people to take away from our conversation today and and perhaps from the book is just that you may think that what's going on in space is kind of separated from your life, doesn't really play a role, doesn't matter so much. It's just, you know, technology stuff.
00:54:35
Speaker
you can kind of ignore it. I would say that actually unbeknownst to you, space space exploration has had an enormous impact on all of our lives through what it's done for understanding of the Earth, what it's done for our sort of day-to-day technology. and And that's going to continue to be amplified into the future.
00:54:56
Speaker
So it is perhaps in your best interest to pay some attention to this because understanding it may be helpful in making life decisions, may be helpful in appreciating where we're going as a species.
00:55:09
Speaker
So it's a surprisingly under examined part of all of our lives, whether we like it or not. Caleb, thank you so much for coming on the show. Maybe the greatest leap isn't into space, but into understanding our place in it.
00:55:23
Speaker
If life is the universe becoming aware of itself, then curiosity is its heartbeat. Until next time, keep asking beautiful questions, and as always, stay curious.
00:55:39
Speaker
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Speaker
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