Finding life near other stars

We are creating this forensic toolkit to find life in the universe, inside our solar system and out. And this place, Carl Sagan's University, was kind of the perfect background of starting this, because he did this such a long time ago. He's one of the giants in the field, right? The pioneer trying to find life out there. This is the contact with the desk one. Touchdown. Hi everyone and welcome to the, I don't know how many episodes of Space Cowboys. It's number 16. 16. Oh, yeah, I thought it's... Oh, that's a good number. Yeah, it is. I thought it's... To the fourth. It's about quality, not quantity. Okay, welcome to a good Space Cowboys podcast. Yes, welcome to a... I like that. That's a really good way, you know. Yeah, exactly. Hey, and the person you're hearing is Lisa Kaltenegger. Yes. Director of the Carl Sagan Institute at Grinnell University in Ithaca, New York. Lisa, welcome. Hi everyone. Thank you. And Lisa, the person you're hearing now is Herbert. Okay, hi Herbert. We weren't introduced so far. Oh, and my name is Thijs, by the way. Don't forget Thijs, but Thijs and Lisa have met sometime in the past. I seem to... Yeah, Lisa... Thijs actually came. Yeah. He came to Grinnell, and so we could talk about all this cool stuff in person. It was a lot of fun. And it was so inspiring. Okay, I hope to do that sometime too. Yeah, please. It was so inspiring. Anytime. It was inspiring. Not only the things that you do, Ithaca itself is beautiful and gorgeous, and just this amazing town in the mountains, basically. And then the things that you researched, Lisa, are so incredible, so far out of this world, pun intended, that, yeah, it was just wonderful to visit you. I think you had just switched names from the Pale Blue Dot Institute to the Carl Sagan Institute. Pale Blue Dot. Yeah. Yeah. Yeah. And we're going to talk for about an hour about exoplanets and finding Earth 2.0. Usually, around this time in the show, we each bring like a story of the week to the table. But we thought we have so much to talk about, and there's actually so much news going on, that we're going to skip all that, and we're going to do some news parts next week about the Falcon Heavy launch, about black hole detection. Yeah. Yeah. Yeah. And stuff like that. And stuff like that. Yeah. Yeah. And stuff like that. I mean, the first picture of a black hole event horizon, all of that is coming next week, so we can chat with you about exoplanets and atmospheres. How does that sound? That sounds great. And we do have to say that our commitment to the show, we're actually doing this instead of watching the press release for the black hole event horizon. So, you know, we are all committed to your view as an atom. OK. Thank you. Thank you, Lisa. We're eternally grateful for the lifetime of the universe. But I believe you secretly told me before. for the show that you've already seen the picture. Is that not so, Lisa? I've seen the one shot, you know, and that's basically what the whole paper is about. And yes, that he was the best kept secret in science, I think. For a while. Exactly, exactly. So, Lisa, before we get into the whole test catalog that came out, because you sort of do have a story of the week, because you just released a new catalog of exoplanets, you are basically on the hunt for a second Earth. Is that a good way to put it? I think that's a great way to put it. And also, it's for the second Earth, for the third Earth, for the fourth Earth, because this whole idea has two key points, right? We want to figure out if we're alone in the universe, and for the first time ever, we have the technical possibilities to actually take a stab at it. But the other thing that's super interesting is also we want to know how our own planet evolves and is going to be in the future. So if we just had a second Earth, a second data point, and then a third, a fourth, a fifth, we could actually figure out how a planet like our own evolves and what's going to come, in a way, and how it fits into this whole evolution of worlds that could be habitats, where things could be alive on, in the universe. And so these two things, to me, are the most interesting in this search. Hey, but that raises a lot of questions already. That's like five minutes in. Yeah. What you're saying now seems to imply that all planets with life on them have the same kind of evolution. Is that what you mean? No. So this is the key question, right? One of the key questions is like, we have our Earth. We have one example. So just a very simple question in a way, if you put it in your mind, is like, well, you know, if you find another planet that's 4.6 billion years old, like the Earth, would evolution be the same? That seems like such a simple question, right? But because we have one data point, our own Earth, we have no idea. So just finding one that's basically the same age and checking in the atmosphere for its evolutionary stage, right? And the only thing we can use is our own Earth as a template or as a ruler, if you want to say, you know, to say like, ooh, it looks like a young Earth or not. So even such a fundamental question like, what actually determines the evolutionary timescale on a planet when it gets to life, when it doesn't get to life? Do dinosaurs die out? Do they invent nuclear? Do they impact nuclear bombs? Yeah, exactly. And so the key thing is like these fundamental questions. What do we need for life to get started? And how does a planet evolve in the first place? How fast, you know, what sets the evolutionary time clock? All of these are part of this intrinsic, fascinating puzzle that we're trying to answer or at least, you know, tease some of the pieces out in our search for other planets. And the more planets we have, the more we'll learn. Exactly. So you're trying to basically by looking at other planets, you're trying to learn more about Earth. Absolutely. So as I said, the one great thing, of course, too, is I want to know if I'm alone in the universe. I would love to have this other connection of how we fit in. What is our connection to the cosmos, you know? Honestly, I want to go out at night and look up at the stars and be able to point at one of those and say, ooh, look over there. There's another planet that could be, or hopefully in the far future when we have a better telescope, is like ours, right? Yeah. And some of you might just be looking. So that's definitely one of the things that I want to do. But the other really important part is if you don't care if there's life in the universe, you should care what's going to happen to our own planet. And yes, it's not going to tell us what's going to happen in a hundred years, but it's going to let us understand how our planet works by looking at other similar planets and then tracing back if they're all the same, what I don't think so, but the key thing is like right now from everything we've learned is that we think that one in five stars, so when you go out at night and count to five when you see the stars up, then basically one out of those five stars has a planet that could potentially be like our own. Small enough so it's a rock and at the right distance. And then we have 200 billion stars in our galaxy, the Milky Way alone. So 40 billion at least to potential other Earths. So you're not going to be out of work anytime soon. That is true. But even if not all of them are the same, we should have like enough to piece together the story of how a planet like ours evolves, even if it's not the norm. And maybe we are the norm, you know. It's going to be so interesting whatever we find. Yeah. It would be very surprising if any planet out there would be just like the Earth. Yeah. To me, it would. I completely agree with you because this is one of the really funny things. This week we actually had a press release yesterday, actually. Yeah. Just out. Where we looked at what the UV surface environment would be at the closest stars that have planets to our star, the Sun. And we compared it to the Earth. And it actually turns out that it's worse than on current Earth, but not worse than on early Earth where we know we had life. But even if that were the case, I completely agree with Herbert. I don't expect a carbon copy of our own planet. Why should I? You know, the dinosaurs would have to die out. But I expect this fascinating diversity and I sometimes think I can't even imagine that wonders that we can find in a way. So you also look at early Earth, right? Is that how you try to figure out what the Earth what an Earth can look like by looking at what our own Earth used to be? Absolutely. And the whole thing actually starts in the Netherlands. It starts at Estek. You're kidding. Okay. Enlighten us. In India. But when I finished my degree in Austria, so I'm from Austria, a tiny country. Kuchel, right? Close to Salzburg. It's about a thousand people in the center and 70,000 if you add everyone. Pretty dark skies? Yeah, very dark sky. We didn't have a street light for the longest time. So I'm used to seeing the Milky Way. Is that where your inspiration came from? I don't know. I think actually I was so curious about so many different things. And then when I started to study, there was this physics and engineering, how what's going to happen in anything, like in the next couple of minutes, you know, quantum mechanics, electrodynamics and so on. And then there was astronomy. And astronomy was this complementary view of, ooh, this big galaxy, you know, it could be this shape or that. So to me, both of them were great in a connected kind of way. And so I'm sure that seeing the stars as a kid has influenced that, too, but more on a level that I don't really, like, it's not as if I saw the stars and say, oh, I want to do astronomy. I just, like, saw the stars and then I saw, like, the rocks next to me and the plants next to me. I was like, ooh, I'm really interested how all of this works. Can I ask you a question that may be slightly off topic, but since you're from Austria, you work very hard to lose any German accent that you may have had. I think the answer is thank you. I love languages. And I love, I think, as you see in the Netherlands a lot, too, you know, people who speak English a lot kind of lose the accident. There you go. But the interesting, I think the interesting thing is, like, if you just have friends that let you practice, you know, just by speaking about normal stuff, and then if you have any of those friends who want to get better at a language, please, please, please correct them. Because you might feel unpolite, but that's the only way they're going to get better. They're going to learn, or they're going to do, like, you know, they're going to do the same mistake over and over again until they think it's right. So I was lucky that people were like, you know, happily let me talk and talk and talk, and they were like, oh, Lisa, you know. That's probably not the word you want to use. Exactly. You need that friend. You need that friend. And so a little bit about you. Then you, from Austria, from Kugel, you also went to the Max Planck Institute in Heidelberg, right? In Germany. Do you want to tell the story about Holland first or not? Oh, and then, I just wanted to put that in there. We got time. I just wanted to put that in there so that we all know your journey. And then from the Max Planck Institute, you went to where you are now. Is that correct? Yeah, and in between, so from Aztec or from the Netherlands, I went to Harvard, and then from Harvard to Germany, and then from Germany to the Max Planck Institute, and then from Germany to here, and I have an IKEA shelf that's surprisingly sturdy. That made the trip with me. Now I actually bolted it to the wall because it's not as sturdy anymore. Oh, wow. I thought they would fall apart a little bit. Me too. Yeah, exactly. But the fun thing is, like, it's actually really great when people pay for your moving. I highly appreciate that. But the funny part is, like, they pay for your moving, not for new furniture. And so if you have, like, an IKEA shelf, you're like, you know what? It would actually be cheaper if I just bought a new one. But okay. Exactly. But did you say that you were also at Aztec yourself? Yes. Oh, okay. So that totally ties into the story that you wanted to tell. Oh, don't worry. That's my first. So when I left Austria, I went to Aztec. I was one of the young engineers. They have this young engineer program where you work. And in Austria, you can actually get your PhD if you work somewhere where you do science. And so basically, my university allowed me to do the science at Aztec at the European Space Agency Science and Technology Center and then basically come back and just defend it. And so this is how it fits in. And when I was at Aztec, what I did is actually I designed or helped in the design of the mission that was called Darwin. And I was supposed to find all these Earth-like planets and characterize them for signs of life. And we were way ahead of our time. You know, that's really some of the thing that happens a lot. So it hasn't been selected yet. Not even yet. It was supposed to fly in 2017 when I was building the thing. But one of the things that came up is what are you looking for? With your camera, with your instruments. And so we had the spectrum, the light fingerprint. So when you look at the Earth, how it would appear to you, I'll call it light fingerprint if I may, through the show. But basically, we had that for the Earth, current Earth, present day Earth. So the light gives off a certain specific fingerprint. You can measure that. And so every type of planet with an atmosphere, I would assume, gives off its own fingerprint. And it's basically the interaction of the sunlight or the starlight that hits it with the molecules and atom in the air. Because if you hit, for example, a molecule with the right energy, light is energy, and how energetic it is is actually shown in its colors, if you want, or in its wavelength. So if you hit a molecule, let's say an oxygen, two O's, with the right kind of energy, they will start to swing and rotate that molecule, right? If you hit, for example, an ozone, that's three O's stuck together, you need a different kind of energy to make it rotate and swing. And so by what energy does not get to your telescope, that's basically like a passport stamp that tells you what molecule or atom the light encountered before going to you. And summed up, all these different missing light pieces make a spectrum. So basically, if you split the light from blue to red or in its wavelength, then you can see what's missing. And what's missing tells you what's the chemical makeup of the air. And so every planet has its unique fingerprint. Not only what molecules are present, but also how many of them there are, what the composition of the atmosphere is. Yeah, so yes or no. Yes. So generally, yes. How many there are, but you have to say in the part of the atmosphere that you can probe. So if you think of Venus, it has all these big, big clouds, so you can't see them. So you can only probe the part above. So that's just the only thing. Yes, how many there are, but only in the part you can see with your telescope or the light can penetrate. And so that's just the only caveat on that. And you were already able to do that when you were at ESTEC working on the Darwin. I mean, that was back then. So this is about 20 years ago, I think. Yeah. So basically, we had this spectral fingerprint or the light fingerprint of our own Earth, right, because you can observe it with satellites, how it would look like. And then we say, okay, how good does our camera, our instrument need to be to find a planet like that around a star that is five light years away, 10 light, 15 light years away, right? And so then this is where everything came together, because you talked about the Earth through time. Because I said, well, what about an early Earth, right? We had life, and why do we only use a carbon copy? That's what you just said before, right? A carbon copy is going to be very unlikely. And so we don't have much information about other kinds of Earths, but we could use our own Earths as a template through time, the parts that we can assess, so the past. And so I kept talking about this, talking about this, talking about this, and nobody wanted to do it, because it's actually hard work, as I found out later. And then I met somebody from Harvard at one of the conferences where I was showing the work that I was doing, Derrick Esteg for the Starboard Mission, what we could do with such a mission, finding signs of biologic activity on other planets. And then he said, well, you know, if you think that's important, you'll have to come and do it, right? And I was like, it was really funny, because the one thing, you're talking to this professor at Harvard, right? And I was looking left and right, and I was like, oh yeah, of course you're talking to me, right? It was just this whole mentality of coming from this tiny town, and I was like, this person from Harvard is just talking to somebody over my shoulder, right? It's just one of those things. I've got to look so terribly bad thinking that he talked to me, right? You know there's sometimes where somebody says hi, and you're like, hi, and then they actually talk to the person behind you, and you're like, oh, yes, I don't know you. It's a scene from a comedy movie, right? Yeah, yeah, yeah. Too often happens in real life, right? Why is this stranger waving at me? Okay, I'll wave back just in case. But having said that, and so he was serious, and he was like, well, you know, you should do that. And they had a model for our current Earth, because they were flying balloon experiments that were testing what the chemical makeup of the upper part of our air was. And so it took forever, but it was a lot of work to try to actually take this code, or to take this code, and make it into a code that could take input from a different colored sun and to say, okay, if it's not just the upper atmosphere that here on the Earth I'm probing, but what about if this planet were far away and got actually shown on with light by the sun, their sun, and then that light reflected back, or the planet went in our line of sight to the star. And so all of this, but it started in Holland. It started in the Netherlands, sorry. It started at ESTEC, where I was like, somebody has to do this. And it turned out I had to do it myself. Because then you went on to become basically a specialist in the atmospheres of planets, of exoplanets, of planets that are not in our solar system. Absolutely. And that's a crazy niche. It's a crazy niche. It only comes from, I want to be able to measure this, right, or I want us to build instruments that won't miss signs of life, right? Kind of worst thing would be if we build a big instrument that can look for signs of life, and then we are too narrow-minded, you know, to think about other kinds of life, and we miss it. You know, that would be terrible. And so it sounds kind of funny, but so this is why one of the things that is kind of clear to me in my mind, but again, it comes from talking to lots of people, and one of your interests is that you have to look at all the different kinds of life on the Earth, right? To try to get, like, brackets of, ooh, it could be green, it could be red, it could make oxygen, it could do this and that, but to basically give us a little bit of a leeway, a little bit of a, I don't know, a little bit out-of-the-box thinking. So it's not just going to be a carbon copy with green vegetation right now, animals, you and me, right? It could be different, and that's what we want to not miss. Yeah. And so are you then collecting basically also samples from an old Earth to see how the atmosphere was, millions of years ago, to see how a possible planet somewhere else could look like? Is that how that works? So basically, that was really the base of my first ever paper that I wrote at Harvard and took, like, three years to get this together. It was really, like, and then it became, it was actually a really fun press story, it became the alien ID chart, right? The alien ID chart. I was saying how our planet would have looked like if you could just get its light through its geological evolution, and it's, it turns out, one of the big questions that I wanted to know is, like, so we have 4.6 billion years old, roughly, our planet. How long could you have figured out that there was life on our planet? Oh, do we have the answer? Yes, that was my first paper. So what's the answer? So the answer was about 2 billion years ago, a little bit more, because free oxygen with reducing gas like methane in the atmosphere is really that telltale sign of life as we know it. Mm-hmm. And we can't explain it otherwise. We can't explain it just by geology, volcanoes, but it was the first time that we actually put together how long that would have worked for our own planet. And it was really funny because I think in the same year or one year after I was at a conference and Stephen Hawkins had just talked about how we should not show signs of ourselves because the aliens are going to come and eat us. Oh, yeah. And so the problem was, like, in a way, if you take this serious, the one thing you'd have to do is to filter out all the oxygen in our air, right? Oh, yeah. What would not be healthy, you know, in a way. So we're already giving that out, basically. For 2 billion years, you know, if they had the same technology as we have, let's say, like, five years more, right? We need this big telescope to get enough light from these planets that are very dim because they're so small. So if they had our level of technology, what probably is not that high, if we're looking for advanced civilization, right? They could have found us for 2 billion years. And so nobody has eaten us yet. So I have I'm an optimist that nobody's going to come and eat us because we're not as tasty as we think we are. Okay. But now I'd like to know because please remind me how long has life existed? I mean, how long has life been? How long would life be able to keep to stay under the radar? Yeah. So to speak. So it's a plus and minus, right? Yeah. Because so our we definitely know that life has existed for 3.5 billion years. There's a big debate about 3.8 billion year fossils that indicate life. We know at 4.2 billion years ago, so very close to the formation of the Earth already, there was liquid water. And the idea is that once you have liquid water, then life probably, because we have the 3.5 find that there's already life and the debated 3.8 is fast in starting to get together. Again, we don't really know what you need for life. But you know, your question was like, how long does life produce signatures that are not unique? Yeah. And so basically that is about 1.5 to 2 billion years for our own planet for the evolutionary stage we do under the radar. Initially, life produces CO2 and methane. And it's not as if we can spot this. We can spot this, but you can also get this from volcanoes. So CO2 and methane can come out of volcanoes. And so what we do or what's my strong belief is actually I don't want to say I think we found life and then I can explain it with a volcano eruption or something else. Yeah, sure. There we go with Carl Sagan. Extraordinary evidence is required for extraordinary discoveries. Absolutely. And I think finding life on another planet, we'd better be sure we have no other explanation than life to produce those signals. Yeah. We'll talk about Carl Sagan in a bit, but maybe we should talk about how you actually do this, how you're actually finding. Well, what I find amazing about exoplanets is the following, that when I was young and I think when we were all young, we hardly knew, right? Absolutely. If they existed. The first exoplanet detection was 1992, I believe. So 1995 around a sun-like star, 1992 and around the remnants. So a star exploded and there's a remnant, a hot, we call it a pulsar because it actually rotates and has a magnetic field. But so 1992, planets we can't really explain because they are around an exploded star core. In 1995, the first planet that was actually around the star, like you think about, you know, our sun really pretty similar. Super recent in cosmic terms. And basically an unknown, we looked up as children at the night sky, like not knowing if there were planets. And now we have thousands because of Kepler and because of the new telescope tests. Yes. And so. Can you take, just take us through how we find these exoplanets and then what, what do you do with them? Absolutely. So how we found this exoplanet. So most of the finding, I leave to other people who like finding, once they found it, I check, Ooh, could this with somebody else's job. I don't want to do all the jobs, right? I do have about like 48 hours a day, right? But not more. 24 hours because this is a science show, right? Oh yeah. But basically the key thing is like the, the way we find, right? So the way we find these exoplanets, we find them, we find them, we find them, we find them, we find them, we find them, we find them we find them like the way we find planets. We, royal we, you know, I don't do that, but basically the way we find planets, they had two major ways to do it. One is when the planet goes around the star, it actually gravitationally tucks with its gravity on the star. So the star, you can think about, leans back to balance the system. They both move around the center of mass, right? But the way to think about it, or if you want to know where the star is, when the planet is, just think the planet actually pulls, and the star leans back. And so you see the star wobble a little bit in the sky. I mean, a little bit. Absolutely. When it goes around it, you can see it wobble. It goes back and forth as this balancing or going around the center of mass. And so that actually we can see in the light. And that's the wobble method, as you were saying, or the Doppler velocity method, where we can actually look at the light of the star and figure out how it moves. And because it moves ever so slightly, the mass that tugs on it can only be a tiny mass. And so that must be a planet. That's how you do that. And the second method is a star is really nice and bright because we see the bright surface. It's hot. It emits light. So we see this bright, glowing stellar surface. But if by chance, and that's a chance alignment, about 10% of the cases, that planet goes between our line of sight, and the star, it blocks temporarily part of this hot stellar surface from our view. And so the star appears ever so slightly dimmer periodically. If you had the Earth, it would be once a year that the sun appears dimmer due to the Earth. Once every 11 years due to Jupiter. So they would be more dim because Jupiter is bigger. And so that is how we can then, using Kepler's law, or Newton's version of Kepler's law, to apply it to any kind of star, not just our sun, figure out from the period how long the planet takes to go around the star, or how long it takes the star to wobble, same thing. We can figure out how far away the planet is from its star. And that's when I become really interested. Because then I say, okay, so is it too hot or too cold for it to have liquid water if we just put an Earth there as a first trial? And then, of course, the planet has to be... Can you combine? Can you combine? Can you combine? Can you combine these techniques as well to find out more about an exoplanet? For some of those planets with the stars, some of the stars that have planets, we can actually find the planet with both methods. So we get a mass and we get a radius. Because the radius is how much light it blocks from the stellar surface, from our view, right? So you can say how big the planet is compared to its star, how much percentage of the stellar surface it blocks out tells you how big the planet is compared to its star. And then how much the star wobbles tells you how massive the planet is compared to the star. And the inclination of the orbit does some errors on it. But if it transits, if you can see the transit, so the blocking of the light, you know the inclination of the orbit of the star and the planet because it basically passes between you and the star. And then you have a mass and a radius and you can go to mean density. What's huge? Because that tells you whether or not it's a rock like the Earth or whether it's a gas ball like Saturn and Jupiter and the gas giants. And a fun way to think about it is you had a big giant bathtub and you threw the Earth in. It's a stone, right? It's a big bathtub. It's a big bathtub. And then you threw Saturn in. It would swim like a cork. Because the mean density of Saturn is lower than the mean density of water. Or water. Or water. That is basically when you have the mean density, when you can figure out if this is made out of rock or if you want marshmallows, right? It's actually an interesting thing to know. Can I take you back one step concerning these methods? Because both work best or even work only when the planet revolves around the star in the same plane as we do. In the plane of the line of sight. It needs to pass in front of it, you mean. So you're missing a whole lot. Only the transit method. Only the transit, yeah. But the other method does not work when the planet revolves around the sun perpendicular to the line of sight. So you're missing a whole lot, right? Is that true? Does anybody ever guesstimate how many planets you miss when you have no other methods? Yeah. So basically there are actually. I have to be honest that there are three other methods, but they haven't actually yielded too many planets yet. So I didn't. I just glossed over it. Okay. But the key thing is like for the transit method, you can actually calculate very easily, you know, the size of the star and you know how long you would see a planet blocking your line of sight, depending on what the inclination is of the orbit, right? To our line of sight and how far away the planet is from the star. You can make a model yourself if you want, right? Because. If it's perfectly aligned, the further away the planet is, you still will see a transit. But it's a little bit misaligned. If the planet is just far enough, it won't go in front of the bright stellar surface from our point of view. That's right. Yeah. So you can calculate that. And for big planets close to the star, for Jupiters and hot Jupiters, the probability is somewhere about 15% that you'll see them. So there is 85% of planets that we don't see. Yeah. Yeah. And then if you go to smaller planets that are further away, then the probability actually goes down to 10% to 5%. So you're missing more. You're missing more and more. So what we're really seeing is the tip of the iceberg, right? That's right. So all these other planets we can infer. No, I completely agree. So as we were talking about before, we have thousands, about 4,000 right now, confirmed planets around other stars. Yeah. But that, if we take these 4,000, when we say they're only 10%. You know, averaging over all stellar radii and distances and stuff, roughly. Then we have actually not found the other 90%. Yeah. And so these 4,000 tell us that there are tens of thousands that must be out there. Exactly. Because other than that, we couldn't have found the 4,000. And is there a strong bias in this tip of the iceberg as well? Oh, initially, absolutely. So initially, the strongest bias was like for both methods, the more massive the planet is. And the bigger it is, the more light it blocks, right? The easier it is for us to find. And then the faster it goes around the star. So if it only needs, let's say, actually the fastest planets we found need only 12 hours. What? To go around the star. And we have no idea how this works. Like a big, hot Jupiter circling its star every 12 hours. Wow. But basically, if you think about it, then it only takes you, right, about a day or two to find it. Because you want to see the transit once, right? Yeah. And then you want to see it again. So it's not something that flew by, by chance, through your point of view. And so you want to see it at least twice. So three would be perfect, but twice is okay. Oh, yeah. And so then basically, if it needs 12 hours to go around the star, in a day, you've got it. Yeah. If it needs a year, good luck finding that kind of observation time. Yeah. Somebody to give you that. Let alone the real Jupiter, which takes about 12 years. Yeah, 11 years. Oh, yeah. Yeah, exactly. So it will take you 30 years to even find it. Yeah. Absolutely. And so basically, this is where the initial bias was so strong that we kind of got the impression that all the planets out there are big, close to the star, just because these were the ones we could find, right? Low-hanging fruit. And this is why Kepler was crucial. So we basically put this— Kepler telescope, right? The Kepler mission. The Kepler telescope. So they proposed a telescope to NASA that would look for three years straight at a patch of the sky. That's actually really, really difficult. Tiny. If you just take your hand and stretch it out and, like, you know, move your fingers apart and put that on the sky, that's the Kepler field of view. That's what Kepler looked at and found thousands of planets in. Thousands of planets in that little bitty, bitty patch. Just sort of to confirm, like, yes, this thing is real. And then you can say, you know, 4,000 here, and then you do your hand over there, 4,000 here, 4,000 here, and you run out of, you know. It's a fun math exercise, but it takes a while. So the key thing is, like, so Kepler then—we designed, or astronomers designed Kepler to look at a patch of the sky that holds 150,000 stars and just stare. So you wouldn't have the bias of you only finding the short-term planets, right? You would just keep staring at this patch of the sky. And so Kepler found thousands of planets, and it showed that actually the small planets are more common. Good. Which is crazy, right? It's great for us. Yeah, great for me, too. Yeah. But it basically showed that a planet that is a bit smaller than Neptune and about the size of the Earth, because then at the Earth's size, it becomes that we're not as sensitive to the planets anymore. It's hard to pick them up. So there we don't really know how many there are. But if you just plot it, you said, okay, how many planets are there on one axis? And then you said, how big are they? The small ones are. The big ones are like a small number, the Jupiters. Okay. And then the smaller the planets get, the more of these planets you have, the bigger the number is. And at the end, where it's like one Earth mass, we, again, are not complete. We don't really know what that number is. But the slope is promising. It goes up, up, up, up, up, up. Oh, yeah? These big Earths. Yeah. Yeah. These big Earths, these super Earths that you heard about. But again, there's an observation bias in it. And so hopefully, tests will help us with that. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Actually, one. I was at the launch. Oh, wow. Oh, great. And I'm on a science team, so I should know when we launched our missions. Yeah, sure. Yes. So we launched in April last year. It was amazing. My first ever rocket launch. I took my then three-year-old down to the rocket launch. And she was so cool because it was like her and me, my first rocket launch. Like I'm 42 right now. So I was 41 then. And her first rocket launch. Yep. Yep. Yep. And then she went back. back to childcare so like we went to rocket launch i'm like please let this be her first ever memory just a cool parent from here on out exactly where was this where it was launched from it was in florida at cape canaveral and it was it was on a falcon nine so it actually came back down we couldn't see this came back down but it was great because the whole team was there most of the team were there and he was just like we're just standing there and counting down and we're like please don't explode yeah exactly oh wow yeah it was great it was emotional it was beautiful it was really cool and you were waiting for this for this one to go up for a very long time because kepler of course had its had its trouble um i mean found a lot had it had some trouble still found a lot but you when i visited you you were already talking about tests like hoping absolutely you know it would go up soon because the key thing with kepler is kepler is amazing mission and everything we have right now in terms of statistic knowing how many planets are there around the stars, we have from Kepler, right? Because it stared at 150,000 stars and it found way more planets than we expected. However, to be able to stare at 150,000 stars at the same time, they have to be far away from you. It's like when you're at a party and you have to take a picture of the whole family or the whole party, right? You go as far away as possible to get everybody on. And so that's what Kepler did. And the difference to it, TESS, is actually scanning the whole sky, the closest, brightest stars for these planets. And so you're in the middle of the party and instead of looking at everyone at the same time, you just take snapshots in different directions. But the people are closer to you. The stars are closer to you. And the key point is if you want to characterize a planet or any object, really, you have to catch its light in your telescope and then again, split it out in its colors to see what light is missing, what the chemical composition, of its air are. But if that planet is closer, so it's orbiting a star close to you, you get more light with the same kind of telescope or you get more light from it because it's brighter, it appears brighter. So you can do more with that light. If it's very far away, it's so hard to catch enough photons, enough light to do the splitting up in the different colors and try to do the chemical makeup of the planets. So Kepler gave us the statistic. That's what he was done for it. This is what we organized it for. That's what it was designed for. It was never designed to actually then follow up those planets because we knew they would be too far away, even with the 40 meter, extremely large telescope repeating in Chile. We're building in Chile right now that should be operational by 224 or the James Webb that should be operational in 2021. Yeah, right. Right. Yeah, that's the space telescope after Hubble and it's 6.5 meter in diameter. So these are the first two that would... Actually, that are big enough to catch enough photons from such a small planet to let us look at the atmosphere, explore what's going on there. Even though we're not there, the light passing through the atmosphere on its way to us gives us all these clue of what the planetary air makeup, the chemical makeup, if something is breathing there and so on and so forth. So you're really waiting for these. Yeah, you're really waiting for these telescopes to be operational. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Oh, thank you, Lisa. My nightmares will finally go away. Your nightmares will morph into this thing actually falling onto the 40-meter telescope. No, no, no. Because we're building that one later. So it's going to be funny. So when will this be done? 2024, you said? Yeah, so that's the extremely large telescope. The extremely large telescope. The ESOS building, the European South Observatory. So lots of different countries are pulling together to build this huge, about, it's 38-point something, but about 40-meter diameter telescope in Chile in the Atacama Desert. Where it's dry and it's high up. So it gets less moisture in the air because the moisture in the air and the different heat in the air above the telescope blurs the image that we get from a planet or any object. So the higher and the drier you can make the sight, the better. This is why a lot of these big telescopes are in the Atacama Desert in Chile. It's a high desert, very dry. And so, yeah, 2024 is when that one should go online. How do you build a 40-meter telescope? I can hardly imagine one. Out of pieces. Out of small pieces. No, sorry, sorry. Thank you. Lego. Lego. That was not supposed to be cheeky. Sorry. It's actually, it's got to be a mirror that is not one dish. So the mirror is not one thing. It has different small pieces that work together, like for the James Webb telescope, right? It has all these pieces that will snap together, but it's not one beautiful, crafted mirror because we couldn't launch it for the James Webb. And for the 40-meter, just getting it up. The mountain. And also maintaining it and doing it. Yeah. So if you can make it out of small mirrors that work together like a big mirror, that's usually what we do for the really big telescopes. Yeah. And so we'll then, I mean, if I hear your whole story correctly, then these two telescopes will, if there's life on these exoplanets, they will be able to find it. If there's life on an exoplanet close to us. So we've test, we're finding these targets. And then this is. We test your finding of targets. We're finding the targets, but you're already finding. Yes. Maybe Earth's pretty close to us. Okay. But what will the limit be? What's the sphere inside which you will be looking? Yeah. So basically that depends a lot on the brightness of the star. This is why it's not just 30 light years, right? So the closer, the better. But the thing is, like, if you have like a tiny star, right, then actually the planet going in front of it is actually whooping. Signal, right? Because if the planet is Earth size, if you have like a very big star, then a planet like Earth going in front of it is a tiny percentage of the brightness. Sure. And so then it's harder to find. So all of this folds in on where we want to follow up, where we can get the most light that actually got filtered through the air from. And so in a first order approximation, the closest stars are always going to give you most light. Absolutely. The closest their planets. But then there will be like. How big is that planet? You know, how big is that star? How much how bright does it appear to us? Like how much light gives it out? Because a small red star is kind of much dimmer than a big sun like star. And so all of this goes in the calculation. But if I do a back of the envelope, I would say somewhere between 30 and 100, 150 light years. You also want a planet with a thick atmosphere, I guess. Oh, yeah. You know, my wish list, you know, I was just like, oh, I would like a planet. With some oceans, a thick atmosphere, a life that has evolved to actually produce oxygen so I can spot it, you know, and so on and so forth. And not many clouds because clouds actually obscure. You want a sunny planet. Yeah, absolutely. See, see, see, see. I think we're thinking alike. Yeah, absolutely. And so, I mean, it's been pretty mind blowing. Ellen Stofan, the former head scientist at NASA, once said that if there's life, we know where to look and we know how to look. If it's there. We'll find it within a decade or two. And this is one of those techniques that she was talking about, right? I think visionary is definitely the way to get us there. But, yes, the key thing, the really interesting thing that we do not know is whether or not life would have evolved to that stage where there is telltale science, right? Because if the planet that we find close to us has life, but it only produces CO2, right, or methane, I don't know. Yeah. Yeah. You wouldn't be able to pick it up. And it would be like, ooh, super interesting, right? That could be life, but it wouldn't be the telltale sign. So, fold it into this question if we can find it, right? You know, you can actually turn it around and say, like, if life gets made wherever it can, then there will be life close to us, right? Because we have these planets that are potential habitats. And if it leaves telltale signs, then we'll definitely find it with the next telescopes. And it's going to be at the… One of the things I should mention, it's going to be at the brink of technical possibility. This is not going to be easy. This is going to be counting every photon. It sounds so easy, Lisa. I know. It sounds so easy. You make it sound so easy. But, you know, you just go and say, like, oh, we've got to find life. That's going to be easy. You know, it's just like, yeah, and then what are we going to do on Tuesday? You know? Exactly. Exactly. But if I understand you correctly, you are the world's expert on the atmospheres of exoplanets. But have you ever been able to measure the atmosphere of an exoplanet directly? So, basically, a friend of mine, and I've helped on it, but a friend of mine is doing that, Nicole, who's also here at the Carl Sagan Institute, Nicole Lewis. And she's doing it. Lots of other people are doing it, too. Sorry. And, for example, one of the people who's doing amazing work is Ignaz Snellen at the Leiden University and his team. Right. I'm writing that down. And his team. You know, no, absolutely. We're inviting him. Great work. You should, you know. And then, you know, it's like, do you ever heard about Lisa? And it's like, oh, man, yes. No, no. They're great people. And they do. It's fun work. And great work. And so, there's a different people who are really excited about this gas giants, and they are amazing. Right. I love gas giants, but not as much as I like rocky planets that could have life. Yeah, you want to find Earth. So, I decided to do that. And why I'm doing it right now, right, you could say, well, why don't you just look at the gas giants right now? And when the telescopes are ready, you go and look at the rocky planets. What we need to know is we need to know how long we need to look to not miss life if it's there. So, what we're building is a spectral database of different kinds of life and different kinds of planets and what their telltale signs would be and if there were some, right? So that when we have these planets that we can then observe with the big telescope to come, James Webb and the extremely large telescope in Chile, then we know how long we have to observe. You know, not exactly because our models are not exactly correct, but we know the bracket, right? Yeah. Because, like, if we observe them. If we observe them for 15 hours and then basically do not find these signals, then they are not like our planet, right? And they don't have life like ours, right? So, we need that number. It might be 100 hours, right? 15 hours is low-balling it. But we need to know what that is because let's say it's 15 hours and then we don't know and we say, oh, let's look for 10. And we missed it. You know, we don't need to miss it. No, no, no. This is why I'm actually right now not doing the real observations. Lots of people are doing that. They're finding great stuff. They're finding great stuff. The Jupiters are gas planets like we expected them to be. They are super hot. So, lots of interesting physics going on. Yeah. But they're not the one that I like to work with. Yeah, you're trying to organize this data, basically. Yeah. I'm basically – and I'm putting it up – so, the idea is to have, if you want in your mind, this data cube. So, for example, you have the Earth, one data point. And then one axis is the Earth through geological time, right? And one would be more massive or bigger. And one would be, like, smaller, right? And less massive. One would be, like, different kind of gases. More volcanism, less volcanism. Different kind of biology. So, you have all these axes that somebody has to actually just put together. And so, like, if the planet were like this, you know, or if life were not green plants but, I don't know, an algae bloom, you know, how would that differ what we could observe? Yeah. And that's basically what we're working on before this telescope go up. Right. And you spoke of gas giants. I spoke of giants a couple of times. Do they have zero probability of harboring life or just a lower one? So, basically, from – this is now a biology question. And so, from everything that I know discussing with my colleagues in biology, the key point is that they think for life to form or to evolve, to start, you need a rocky surface or something to surface. Something to cling to. Something to cling to. Yeah. And you also want shallow water so that you can actually evaporate. Yeah. And concentrate the chemistry. Because the idea is if you had, like, a huge ocean, the chemistry wouldn't be concentrated enough to start to form RNA and DNA. Okay. Could I summarize like this? Yeah. Go, go. You need solid, you need fluid, and you need gas, all three at the same time. I think so. For the best circumstances. And the gas is debated, right? Because the question is whether or not we could find life in frozen planets, in frozen moons like Europa and Enceladus. That doesn't have really an atmosphere. But it has a solid ice crust, and below it has oceans. And so, is that enough? You know, is there a way that you could actually concentrate the chemistry there somewhere, maybe on the surface of the ocean, like the black smokers here on the depths of the seafloor? Where you have, sorry, such a difference in temperature that that could potentially, like the further away you go, it gets cold really fast. That could also provide a chemical gradient. Right? And so, all this is completely open because what's kind of crazy is we don't know what life needs to get started. Yeah. And so, we're trying to do it in the lab, but of course, it's incredibly difficult. You know, and you have all these different conditions, and you don't know, maybe life needs 100 years to then start, right? And you cannot keep this in solution for 100 years. It's a terrible PhD project, right? Exactly. It would be great if it worked out. Yeah. But so, this is why this search is also so interesting. Mm-hmm. Because it should tell us what the conditions are that you need for life. And in a way, to think about it, it's like you find 100 planets, and then you find signs for life on, let's say, half of them. You know, I'm just making this up. Mm-hmm. And you can say all of them have gone or have started out really warm, right? Then that would tell you that probably, that you need warm conditions for life to get started because you can't see them on the frozen ones. Or in reverse, right? Then, okay, cold conditions is where life can get started. Or anywhere, right? That will tell us again how sensitive life is to any kind of initial conditions. Mm-hmm. And all of this is super interesting because it also gets confounded by this whole thing, the idea is that life only needs to get started in a tiny place at your planet, and then it spreads out and adapts. Yeah, it will spread. Yeah. Yeah, exactly. So, the question is, like, you know, even if we see, like, a really cold planet, maybe there was one hot spot, right? So, but anyway, we basically got to cross that bridge when we see that trouble. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. I'm more than happy to dive into the problems of how to interpret it. Yeah. And Lisa, I've now heard about big Jupiters, big Earths, the hot ones, small ones. Can you just give a, just a quick summary of, like, the coolest planets that we found? Oh, absolutely. Yeah. So, I have my favorite list. So, among them is, well, one of them is the planets around this remnants of a star, this pulsar in 92 was like how the heck could you have a planetary object once the star exploded right so there's a lot of ideas that there was part of the stellar material falling back and forming this second generation planets but it's crazy right your star exploded and then there's something that has a new planet like a zombie planet yeah a zombie planet because where would it get its water from so all of these open questions and then uh one of my personal favorites of course is uh kepler 62 enf and that basically is just that's the first two planets we found or the first planets we found they were small enough and at the right distance in the kepler sample and we didn't just find one we found two so we call this the habitable zone where life where water could be liquid on the surface and so i was part of that discovery and this is also why it's you know it was the first one so i would have loved those planets either way but like an earth and a mars basically yeah but basically the cool thing is like it's like an earth and an earth and mars surface because they're bigger than the earth like about 40 and 60 bigger than our own planet so if you actually moved our own earth to mars's orbit it could actually be warm and have liquid water because it's big enough so that's still tectonically active it would have volcanoes putting out greenhouse gases and so the atmosphere would work very differently than mars because mars is too small cooled out has this tiny atmosphere with not much greenhouse gases it's just too cold but so that system is fascinating because we're like oh it's the first one and i'm like oh wait a second it's not the first planet in the house and we have like two planets in the house and it was crazy and great and give us more give us more i want to hear more about more planets we got a of mine is coro 7b so it's the first rocky planet that we found with the small european mission corot uh the french easter mission and so basically it's the first one that was small enough that we knew it was a rock but it's so hot that it actually has oceans on its surface it must have but not water oceans it would have lava oceans on its surface it's crazy it's this new concept of lava world and this whole idea is like so i know that from video games yeah yeah you have rocks raining down on this planet you know what would the atmosphere look like so it's kind of crazy super interesting you know we have we have this this crazy diversity inside our solar system already you know we have mars from mars to neptune and all these moons and everything yeah i'm i can begin to think of the diversity that's out there around other stars you give us a taste of that yeah oh no absolutely i completely agree with you and so basically you have these lava planets right and then we have other planets that are a little bit bigger than ours like i said the kepler 62 planets e and f and so basically the idea is that they could be completely covered in water being like complete water worlds and if you like to surf or sail right that's the place you want to be but it would actually change the whole customer needs to know this yeah yeah yeah customer needs to know that but basically the idea is if you have enough water then actually on the bottom of your ocean you wouldn't have rocks you would have water and you would have water and you would have water and you would have water you would have ice it's not the ice that swims on top it's a different kind of ice we call it ice seven eight nine ten but basically it's just by actually having enough pressure on ice you start to generate to pressure on water you start to generate ice again doesn't this exist in the earth's oceans as well no it doesn't because we don't have enough pressure but we can do it in the lab to show proof of concept and so the interesting thing in there would be like so you'd have a rocky layer on the bottom of the ocean and then you have the ocean what would that do right to the whole planet would the gases be able to come out would there be fish would they you know i don't know you know but it's because you asked for diversity and then of course one of the things we haven't even touched on is moons around giant planets exactly we haven't found any yet like non-confirmed there was one potential detection of a big moon but anyway that is a completely different uh amazing uh partner to the moon and i think that's a really good point because i think that's a really good point because i think that's a really good point because i think that's a really good point because you've heard where you could have life yeah are these even detectable have you thought about that how could you detect moons around planets around other stars so there's lots of people who thought about this in um there is a way to do it uh but we haven't found you know we have the first potential detection but we don't have any confirmation of that yet and basically how it works is you have when you go back to this transit search you have the planet go around and you see the dimming of the star and that's like clockwork you actually do the fraction of a second now if there's a delay okay the one thing that you can explain it with is that actually this is not just a planet it's a planet moon system yeah so the planet and the moon orbit around each other so basically that delay can translate into knowing that there must be a second object another wobble effect wobble or something like that yeah exactly and so basically it's called transit timing variation if the planet just doesn't come exactly at the right time and of course you can't do that if you don't have the right timing and so you can't do that if you don't have the right timing it's super hard to pick up but we actually really good in measuring this because of the kepler data and we do it in the test data and so there are some first indications that there could be one but we don't have a confirmation of that yet and we haven't found we should be sensitive to things with the mass of the earth and the size of the earth however we haven't found any of those but you know if we would then we don't just have you know one out of five 200 billion stars in our galaxy alone is 40 billion potential earth if i can put in a couple of moons per giant i don't just have 40 billion potential other earth i could have more i've i've won one very different question um and i'm me too so we need you for a couple of more minutes but um i'd like to know this you've told us about methods to um sort of recognize atmospheres where um life possibly plays a role in the development of the earth and the development of the earth and the world um did you ever turn these methods on venus mars europa and cellulose etc absolutely that's your first test case right yeah because if it doesn't work for our solar system you should not try to do it for anything else and we just said uh so last year at the end of last year we actually had another paper out where we just generated this light fingerprint for all the different objects in our solar system as a comparison and did you discover life uh on the earth we did oh well i think we were the first ones but again this is like what we can discover because we can't go there and drill a hole in the ice is only life that modifies the air right so that you can see products of it breathing in or out like oxygen and methane but uh if life were on an ice layer like potentially on europa and solidus you would have to go there and drill a hole in the ice to find the life that you want to find it and that is the problem if that is not in our solar system where we're trying to do that but it's not a star that's so far away right because if you shrink the whole solar system to the size of a cookie then the next star over the one after our sun proxima centauri that happens to actually have a planet that could potentially be like ours what's great news for us yeah we can have a neighbor earth basically but in that scale where our solar system so sun to to the outermost planet is about the size of a cookie that's two football fields away yeah so the distances are vast right so it's 20 years travel or something right yeah it depends how fast you go but yes yeah exactly it can be centuries as well right but basically that is the idea that we've generated this um light fingerprints for all the different objects in our solar system to see whether or not we could spot remotely if there's life that doesn't mean that we can't see it but if we can see it we can see it we can see it and that's the idea that we have but it's not that we can't see it we can't see it we can't see it we can't see it we can't see it so we're using this concept of a habitable zone where it's not too hot and not too cold for there to be liquid water on the surface of the planet because as soon as you put an ice layer then any gases that life would produce can be trapped under that ice layer and not make it into the air so the habitable zone is not where there can only be life or where there has to be life if we find a planet easy where we can find it yes where we can remotely detect it exactly hey lisa it must be so crazy to be so on the at the forefront of of of this knowledge and i keep on i keep on thinking what what would call sagan think well i hope uh that he would actually be in the middle of this right so you'd be down the hallway actually down the hallway yeah i think his office is right there right well actually i am in his office you are in his office that's i mean it's actually really interesting because sometimes i just i was thinking what's my best approach should i just sit there and hope that through osmosis you know but it's kind of really great because i look around and i'm like wow this is you know this is on my bookshelf is a book you may know it is called who got einstein's office oh yeah yeah that's very very funny and you've got a carl sagan's yeah that's a nice second okay thank you very much i'll actually take it as a first yeah oh yeah sure but it's the christen equivalent and you got carl sagan's and you got eddie's office that's a nice second okay thank you very much i'll actually take it as a first oh yeah sure but hey it's a very unique time and i just can i love the fact that you're here um the fact that you're here and i am sorry that's all i know Oh, yeah, sure. I know what you mean, but, you know, for different kinds of flavors of what you want to do. I just like this is also why when Cornell asked me to come and be a professor here and start this interdisciplinary team. And so currently we are 30 faculty from 15 different departments like biology and physics and astronomy and earth and atmospheric science and, you know, engineering and so on. And even to music and science communication. But we are creating this forensic toolkit to find life in the universe inside our solar system and out in this place. Carl Sagan's university was kind of the perfect background of starting this because he did this such a long time ago. He's one of the giants in the field, right? The pioneer trying to find life out there. And so it's kind of really resonating. You know, you go in and you're like, yeah, you know, even if I've never met him, you know, it's kind of. We are following his legacy. You know, we basically running here. This is the cue. It's all that is or ever was or ever will be. We have to hear Uncle Carl in this in this episode, right? Absolutely. Yeah. There's a tingling in the spine, a catch in the voice, a faint sensation as if a distant memory of falling from a great height. I have to watch that again. I have to watch that again. Lisa, it's an honor. It's great that you it's an honor for you and an honor for us to be able to get all that knowledge from you. It's so cool. Yeah, well, it's a fun time in science. And one of the things that started with that, this test paper that we just had two weeks ago or something. Basically, we said now we have this test mission. How many stars? Because we scanning the sky. Right. How many stars can we actually look at? And find a planet who would get the exact same energy that we get from our own sun. And that is small like the Earth, the same size. And so it turns out that among the 400,000 stars we are probing in the whole sky, 1,822. I did some work. That's 1,822 to be sure. Took a lot of time. So I'm going to say 22. We can actually find a planet about the size a little bit bigger than our own. And that's the same energy that gets the exact same energy from its star. And for 408, we can actually find one that is as tiny as our own planet going around another star. And I keep talking about planets being tiny. But honestly, if you take the Earth and you put it 110 times next to each other, that's the diameter of the sun. So that's what we're trying to do. We're trying to find this tiny dot of light. This tiny pale blue dot. And we're going to go to this huge bright sun and reading and exploring its air, its atmosphere to figuring out how it's like. We have to leave it with that. Thank you, Lisa. It's great. We wish you all the luck on your endeavors. And we're sure to read it on front pages of newspapers when you found something. Can you make one final prediction? Of course, of course. And I'll just keep the tune, the cosmos tune in the background. Planetary research has surprises with the sheer number of exoplanets they found. I'm going to predict that in 10 years from now, we'll know about thousands of planets that harbor life. Thousands. That's my prediction. Okay. Okay. Yeah. Case of beer? Case of beer. Sure. I love your predictions. And I'd say like, let's go and find out. And we're going to, yeah, we're going to be all around. You'll be doing the discovering. Your name will be under there, under that article. Hopefully. Hopefully. Hopefully. Hopefully. Oh, thanks so much, Lisa. And- Thanks for having me. Yeah. And I'm sure we'll talk in the future. Okay. Bye. Thank you. Bye. Just want to do a quick preview of next week's episode. Because we're going to talk to ... Gerrit Kminik and he's the planetary protection officer of ESA. Yes. So he's in charge of protecting the planetary environment from us. Yes, from us, humans. From bacteria and all the particles. and all the life forms that we might bring there. Exactly. So keep the planets clean, you guys. Keep the planets clean. And the week after that, we're going to talk to Sarah Markoff, who was involved in the black hole picture that you might have heard about. Also going to be a magnificent, magnificent episode. Exactly. So thanks to everyone. Thanks just basically to everyone. And bye. And bye.