What Mars can teach us about life

Time Markers

00:00 – Episode introduction
00:26 – Welcome 
00:40 – Why this career path?
02:13 – What role did the early Mars mission play in your career choice?
05:17 – Boom & bust cycles, retrenchment & AI advances
09:43 – Are humans special?
11:10 – The search for life
15:36 – Understanding life on Earth
17:18 – The definition of life
22:50 – Mars Sample Return and surprises
28:15 – Space Takes – War and space assets
35:35 – Space Takes – European launch

Transcript – Nathalie Cabrol Conversation

David Ariosto – Dr. Nathalie Cabrol, you are the director of the Carl Sagan Center at the SETI Institute, which stands for the search for extraterrestrial intelligence. It’s, so good to have you on the on the show.

Nathalie Cabrol – Thank you very much for having me.

David Ariosto – You’re also the author of this superb book called The Secret Life of the Universe: An Astrobiologist’s Search for the Origins and Frontiers of Life. And so I think that’s the kind of a good place to kind of get into this conversation, my first question really, is, why? Why have you dedicated your career to sort of understanding the origin and the nature of life in the universe, not just out there, but but also right here on Earth.

Nathalie Cabrol – Yeah. Well, you know, I often have this question, and I always make the same response, which is, I was born in France, and we have this cartoon character, character in France that’s called Asterix, and it has this companion whose name is Obelix. And those two are goals, and they are resisting the Roman Empire. And the whole story is about druids and magic potion and and that’s why they still can’t resist because of the magic potion and Obelix is this gigantic goal. Is really, really big, and cannot have magic potion because he fell into the cauldron when he was little. So that is what happened to me. I fell into the cauldron when I was little. I have no explanation. I w as one like that. I always wanted to do that.

David Ariosto – You know? I mean, it’s that seems to be a theme, that a lot of the people on this show sort of are bitten by the bug, so to speak, at an early age. But, you know, I, I like when I, when I look at your career, it seems like it, it dovetails with a number of things that were happening in space.

So you had the NASA’s Viking missions, which were the first US mission to successfully land on Mars. You had Mariner nine, which was for spacecraft to orbit the red planet. So I’m kind of curious, like, what role did those missions play in your thinking? Because your PhD centers on water on Mars, and sort of like when you think about that, and broad, broad scope of what Mars may have looked like, especially back then, you know, pretty similar to Earth, like polar caps, seasons tilt, questions of water, where it ponded, riverbeds, all of these things seems to kind of coalesce in terms of where you were and what what you were focusing on?

Nathalie Cabrol – Everything in life is a question of timing, and I have to thank my parents for that. I was pretty much born at the same time as planetary exploration. In fact, planetary exploration was born a few years before me, but I was five year old when Armstrong, you know, step foot on the moon.

And then I really did not remember Mariner 9. I was too little. But really that was the time when we went from science fiction and Mars, you know, potentially having Martians, Little Green Men and Crystal cities at the surface to a reality, a scientific reality, that is even for me, you know, even more intriguing, because well, as you just mentioned, you don’t need to invent any words to describe Mars. You have valleys, you have dunes, you have channels, polar caps, volcanoes. This sounds really, really familiar.

My first recollection, my first excitement is, is Viking and Voyager and those two really then I was old enough to start putting things together, which was my call that I felt very, very early on, when I was looking at the sky and all of a sudden having these planetary landscapes in front of me. And why did it start with Mars? Because Mars was the place that was available at the time. Time to study. I mean, really study Voyager was flying by. So we had images, some of them, and they were spectacular, but Viking was really the first planet that had an integrated program of exploration. So little by little, we acquired a lot of data enough for me to do a master and a PhD on whether on Mars, but not necessarily by choice. It was there, and this is where we were starting at the time.

David Ariosto – You know it, it almost strikes me that we that there’s almost a natural boom and bust cycle to a lot of these things, in the sense that you have, you had the Apollo program, you had Voyager when we’re like, pushing beyond the realms of our own solar system. And then there’s lulls, and then you see sort of resurgence. And it strikes me, we’re in a period of resurgence now, not only in terms of the commercial sector, but all of these sort of new technologies that are coming to bear, not only with James Webb not only with the nature of AI and the intersection of sort of quantum technologies, as we start to kind of understand the nature of these things a little bit more. And yet it’s also coming at a time of great pushback with regard to science, growing skepticism of so called experts, you know, questions about funding in terms of these things. So it’s, you know, I wonder if we’re sort of entering this almost like Copernican, like reckoning, in terms of who we are, where we’re, where we’re at, in this sort of technological adolescence of humanity that’s coupled with this moment of real retrenchment from science. And I just wonder how you square the two?

Nathalie Cabrol – Yeah, it’s interesting, because this retrenchment exists. But that depends where you look. You were mentioning exoplanet, and in my book, I talk about the Copernican revolution, because, well, you know, they changed everything. We mentioned Copernicus, just because Copernicus allowed us to figure out that we were not the center of the universe, right, that the sun was not orbiting around the Earth, that the earth was orbiting around the sun, and but still, we felt like, you know, we are special. We are the witness of something. We can witness the sun and the wonders around us and try to understand them, you know, by measuring them, or for other people, just to have faith that, you know, we are so special that God put us there and and all of a sudden, we turn those telescopes and in every single star you look at there’s a planet orbiting around, they are gazillion. And this is a very, very you know, scientific measure, especially considering exoplanet, they’re everywhere. Normally they are everywhere, but they are not exactly like us. We are unique in that sense. We haven’t found yet another solar system per se, but we have found other version of it, and we’ve learned that there are planets that don’t exist in our solar system, and this opened such an incredible new it’s just like a new breath, because you see all these new planetary landscape that you can, you know, foresee and model those planets.

They have different habitability. Some of them don’t in terms of the life as we understand it. They are too hot or too cold, or too weird, for what I know. But many of them are habitable for life as New York, no, it doesn’t mean that they are the same as the Earth, but we’re talking about Super Earth, hot Jupiters, ECN worlds. And all of a sudden you imagine, you know, your imagination takes flight. And as a planetary scientist, I am starting to put together the work industrial extreme environment with these new worlds and AI come on top of that, helping us model and see, you know, what kind of atmosphere, what kind of environment could develop if we were putting all of those together, and if they could survive in the first place. So in that sense, there is a huge revolution. And this one is pretty obvious. It’s in our face. It’s happening every single day, to the point now that it has becoming so main avenue to talk about exoplanets. So they rarely make you know the news anymore, just except when you have some particular particular study. But there are other revolutions going on, much quieter one, and I think that these will have the most. I. Impact in the coming years, and those are happening in the background right now.

David Ariosto – You mentioned, I mean, you mentioned whether we’re special, and I think maybe that strikes the core of this, because there’s been no indication of anything beyond this planet that exists. And yet, foundationally, in terms of what the Drake Equation, sort of that formulation in terms of terms of the possibility of of life out there, suggests I would think, by virtue of what you do, your answer would be, no, we’re not special, but I’m curious. I’m curious, but I put that answer to you.

Nathalie Cabrol – We are special in the sense that we exist, and so far, we are the only you know data point that we know, but at the same time, we don’t understand what life is. To this day, after several decades of searching you know for life, its origin in nature, whether it’s microbial or technologically advanced. We do not have a definition for life. We do not have any definition for intelligence, and we don’t have a definition for consciousness, which are so very critical to understand who we are and why we even exist. So in that we are very special, because we can, you know, ponder over these questions and try to seek answers.

David Ariosto – Well, I guess when we think about with that specifically, I wonder if the public’s idea of this, this notion for for the search of life, is far too narrow, not only in the scope of what you just mentioned, the possibility that the universe is full of bacteria, potentially, at least, of which we’re talking single celled organisms, at least, that’s like a driving theory. There’s not evidence to suggest that beyond, like maybe some biological signatures or sort of possible evidence or indications of past life. But also it seems like there’s a there’s two other sides to this as well, at least two other sides. There’s this once, the search for archeology, in the sense like that, the universe, as we know, is 13.8 billion years old. And so the idea that, you know, human civilization, which are represents fractions upon fractions of a moment in a time. In that moment somehow lines up with another, another entity that suggests complex life would seem incredibly rare. But I think the bigger question is that, is it like just hubris and arrogance to think that other forms of life, particularly complex forms of life, would be distinguishable through our sort of natural physical processes and how we detect things.

Nathalie Cabrol – This is a very interesting question in many respects. The first one is that our search, whether you’re looking for microbes or looking for advanced beings, is still very anthropocentric and geocentric. Yeah. And in fact, when we say we’re searching for life, we are not searching for life. We are searching for the CO evolution of life and environment. Life doesn’t, you know, just appear through the strike of a magic wand, and who we are, us, anything in the biosphere is the result of 4 billion years of evolution, of CO evolution on this world, and that includes this neural network here, The neural box that we have we are completely attuned to the terrestrial environment where we evolve for so long, and there’s so many forms. And you have to think that this is exactly going to be the same for any type of life, whether simple or complex anywhere else. And so thinking that they would, you know, approach questions the same way we do. Because, again, the way we think, the way, the way, you know, we see the world, is really related to our convolution thinking.

They would be the same as our as us. I think this is a big, big step, you know, and so far, we are searching, following the central, centric and geocentric view, but this is what we have right now. Okay, and it’s not completely stupid for a number of reasons. Fact is that the bricks that make us the bricks of life. They are very common. They are the most common stuff in the universe. And they are even more ancient than we thought they were. Thanks to James Webb. We know that. You know, we can see organic, complex organic molecules, 12 billion years in the past, barely right after the universe, you know, formed and so there is that. So the chemistry that makes us is probably very common. That doesn’t say that we are going to look alike or think alike, just because there are so many, many possibilities, just with that, with these bricks, the number of, you know, amino acid, the geometry, the molecules. If only one thing changes, you know, you change a lot of things and and also there, there has to be some common ground throughout the universe. We if they are part of this universe, then they would have to follow some of the same rules, right? Well, yeah, you have the multi multiverse, you know, we can go, let’s start with, you know, we have enough problems right here.

David Ariosto – There’s a progression in terms…. But let’s start there. Let’s actually start right here on Earth.

Nathalie Cabrol – Yeah, and, you know, just to finish the thought here, just because of that, there will be some convergence of form, like an entity that has to survive and evolve to be advanced, means that was able to survive for Quite some time in an environment, whatever it is. So it has to be able to interact with that environment. If it wants to communicate with you, or just is curious about Cosmos, then it has to invent some technology, you know, understand the rules of the universe. Curiosity is going to be something we share. I think that there is no doubt about it, the sharing of information, the sharing of energy, or the way we expand energy, is also something so the small version of this is that there are some fundamental principles about what life could be about.

David Ariosto – I’m sorry, go ahead, finish.

Nathalie Cabrol – I mean, that goes back to the quiet revolution that’s going on right now. Which is that in astrobiology, I mean, which is that for decades, we have been searching for the origins of life, which bottlenecks us into environments that are favorable of the type of chemistry and biochemistry we are made of, um to um, slowly but surely lean into the nature of life, which…

David Ariosto – I think, even even that, I think, is one of the most interesting things, because, you know…

Nathalie Cabrol – For me as well, this is why I’m very interested in right now.

David Ariosto – Yeah, because before you even expand out in terms of all these other definitions of life, and how we might sort of extrapolate out in terms of, you know what constitutes life by other definitions, part of what you do is, is not only looking out there, but looking here, right where life can exist and where it may not seem possible on Earth, and shows this like the nature of things, like tardigrades, I would think these, these Uber tough water bears, the microscopic water bears of sorts, just sort of in the nature of their capacity to survive, at least for a little while, and even in the vacuum of space, the near vacuum of space, it just sort of changes the math a little bit in terms of what we think about, what’s what’s possible, or at least broadens the definition a bit. And so I wonder, like, when you think about that path from the simple to the complex, and like, how rare or inevitable that transition might be in the cosmos, that strikes me as sort of like a fundamental question in terms of your research, in terms of what you do.

Nathalie Cabrol – Yeah, and some of the researchers, and I am really, you know, leaning without my heart and some of my brain, because some of what they do goes way beyond what you know. It’s not my expertise, but some of them are telling you right now that life is the inevitable result of thermodynamics, because it’s the best way to fight entropy. And so what they are saying that is there is a fundamental force in the universe that organized life well, organize whatever is there and is bound to create living forms. So this is where we are starting to talk about the nature of life, which is not, you know, that doesn’t make life a thing. And that’s, I think, the biggest issue right now that we have in front of us is that for us, something is living when we can recognize that it is that we. And see that we can measure it, but life doesn’t care about that. And we already have some part of this paradox embedded in what we are searching right now, which is that most of the community agrees that life did not appear on Earth. We are going back to the magic, you know, one striking it’s a transition. It’s a transition from something to something else. But if it’s a transition, is there even a sense to put a demarcation somewhere right? And then, then the horizon broadens, really, because you’re in front of a cliff, and it’s just, you know, it the difficulty with that is that some completely shifted the paradigm and tell you that life is a property of the universe. How do you prove that? How you know? How do you falsify this theory, not to mention that this is the most experiment, because we are part of it. You know, we are both the observer and the and the observation.

So the idea would be that there is something about the universe that is bound to make things that ultimately we will recognize as living, which is, if we want to go very fast over this to rearrange the flow of energy and the flow of information, but then you have to acknowledge that what is information? Information is energy decoded by something that’s capable of understanding what it says. So today, you know, we are at this incredible moment in time where we are opening doors over an endless horizon. This is not life. Is not only a an experiment in this vial in the lab. You know, it’s not the Milner experiment anymore, although this is, you know, this is important, because we understand maybe where this process happens, in terms of environment and in terms of camp, but it’s only the part we can see, that’s only the tip of the iceberg we can understand.

David Ariosto – And that’s not to say even the least of what we’re potentially even developing on this planet in terms of…

Nathalie Cabrol – And there is that. But if life is a universal principle, you know it’s going to organize itself in ways we cannot fathom at all. And to me, this is incredible. And if you want to push really the envelope, you know, to the very end, I would say this is the kind of life we can imagine with our understanding, the current understanding of the physics that surrounds us in the universe, which, of course, is a reflection of the instruments we have.

David Ariosto – Okay, so, so sort of the last question, the last couple minutes that that we have here, you know, we’ve kind of gone big picture. Now I want to sort of center now a little bit more to here. And now we did that a bit with Earth, but I’m curious, when you look at Mars and sort of coming full circle here, and you think about the nature of this upcoming Mars sample return mission, is it your contention? Is it, is it your, maybe your hope, or your, your your sort of understanding just based on precedent that we may be in for some surprises that make what NASA’s Curiosity rover has found in terms of organic compounds, like akin to that, and perhaps even more or perhaps less, you know, I don’t want to sort of suppose or speculate too much in terms of this, but that, like that, seems like a seminal moment that that’s coming up, not only in terms of the science, but in terms of a broader consciousness, in terms of what’s out there and where we stand within it.

Nathalie Cabrol – Yeah, and it’s definitely intriguing. And you know, if we were seeing this on an exoplanet, I would be a lot more prudent, because obviously we don’t know the environment on an exoplanet. That’s the issue we had. And I had to write a commentary for The Guardian a couple of weeks ago for K2-18b (exoplante), because people were, you know, some scientists were saying, we’re seeing this molecule and it’s potentially a bio signature. This is hard to do when you don’t know the environment, because then you cannot extract the signal of life from it. This is different on Mars.

On Mars, we know the environment fairly well now, and obviously the ratio of Carbon-12 (C12) and Carbon-13 (C13) you that you are referring to, which is usually but not always, associated. With the presence of life. It’s very intriguing, because life is lazy, and if it has to break carbon bonds to, you know, get energy and metabolize then it will go for the weakest one. And so C 12 is the one preferred over C 13. And there is this other thing with the methane. And the methane is here. People were very excited when we were seeing that it was seasonal. As a bomber, it’s seasonal, which means that, you know, it may just be related to more melting, et cetera. But it can also be, well, methane is such a problematic signature, because half of the ways you can form methane, and there are many, are purely geological or cosmic, and the other half is biological. But let me tell you that Marc is is a Rosetta Stone, and I’m not going to get into into it, but it has some of the secret we couldn’t keep because of plate tectonics and erosion here on Earth. And there are so many possibilities.

The first one is that life never appeared on Mars. And that’s, that’s a possibility we have, you know, until we can prove the contrary. It’s, it’s an hypothesis. Another one is that life appeared on Mars and is very different and couldn’t stay at the surface. But considering the environments we know still today. At, you know, deep in Mars, it’s probably still there and thriving, because it has a very, very stable environment deep down, if we find it, we will know if it’s, you know, local, because it will be different. It will be adapted to its environment. And then there are a couple of other possibilities which are really fun. It’s to think that because Mars was cooled down before the earth, and had an ocean before the Earth, but still was bombarded by big asteroids and impact, lots of material was ejected, it’s possible that some organic material, or even prebiotic stuff or early life made its way to Earth and find a great environment to thrive, which means that the Martian we’re seeking maybe are, you know, we are those Martians.

David Ariosto – Inherent, inherently. We are all exactly according this. They were all inherently…

Nathalie Cabrol – Yeah, but we will know it, because if we find it, there will be some genetic footprint, you know, fingerprint. I’m sorry to tell us that the one way is not the only way. The other way is true too, which means that the earth could have sent some material to Mars, and for a billion years, Marc had a very similar environment as the Earth. So maybe we are parents, and maybe it worked both ways, which would be even more fun, and maybe the third way is true, which is that you have a local life on Mars, and contamination both ways. So you know, you can think about this in many, many ways, but we are the threshold of something really fascinating. But to me, beyond all the planets and moons that are so, you know, um, enticing right now, yeah, to me, the search for the nature of life.

David Ariosto – Dr. Nathalie Cabrol, I could talk to you for the next six hours, so we’re gonna have to, have to carve out some time at that point, but thank you so much for joining us. Director of the Carl Sagan center at the SETI Institute. It was my absolute pleasure having you on the show.