Daniel and Kelly wrangle with the tricky science and ethics of sending microbes to distant worlds.
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Hey Kelly, I have an unusual aliens question for you.
It is never good for me when a question starts like that. It's I have an unusual aliens question for you? Or what is in my poop? As a parasitologist, I get a lot of that so go on, I can't wait. Where are you going with this?
All right? So, as a parasitologist, do you ever see a critter infected with something new and wonder hmm is this an alien parasite?
No?
Never, There's so many weird things on Earth. I don't feel like we need to go to space to explain them. And the other day I saw someone trying to make the argument, like in an actual like sciencey pop magazine, that octopus like octopodes. Oh gosh, let's not get into how you pluralize that might be aliens. And I'm like, oh my gosh, dude, their genome fits nicely in the tree of life. This isn't complicated. So the answer is no, all.
Right, But then my question is how exactly can you tell? I mean, do you think like if alien parasites did come to Earth, could they do their parasiting on us? Would they find us tasty or be like incompatible with us?
So that's an interesting question. You know, it might be that they wouldn't be able to eat us, or that they wouldn't be able to like, you know, bind to whatever receptors inside of us they needed to. But you know, for as far as how far or what do you need to do to tell? You know, you could like take a DNA sample and you know, see if they fit on the tree of life or not. But yeah, I don't know hard to know, so I guess I'd say it's impossible to know. But I'm guessing that we do look different from the kind of things that aliens are used to sucking on out in space.
I'm going to take it as a compliment that aliens don't want to suck on any parts of me.
You know, That's exactly how I meant it.
Did Hi, I'm Daniel, I'm a particle physicist, and I'm doing my best to be not attractive to alien parasites.
I'm Kelly Wienersmith, and you probably don't have any alien parasites. But if you do, send them to me, because I'd love to see them.
How are we going to find out? Kelly? Are you planning to chop me up to see?
Sure? Yeah, better you than my kids.
You didn't take very long to think about that. You went right into Yes, I'm gonna chop up my co host.
Some questions are easy to answer.
And welcome to the podcast. Daniel and Orge explain the Universe, a production of iHeartMedia, where we tackle all questions, those that are easy to answer and those that are harder to answer. Questions about the deep nature of the universe, questions about what's out there, questions about how it all works, and questions about who else might be out there in the universe. Orge can't be with us today, but I'm very pleased to have Kelly here to talk to us about aliens landing on Earth and potentially sending our parasites out to alien planets.
Oh, is this the world needs more parasites? I'm so excited. The universe needs more parasites, not just the world share them? No know, is that a weird take? I don't.
I'll admit I have a hard time getting warm and fuzzies for parasites. I always think of those wasps that like lay their eggs inside spiders and then control them until they die, driving them around like some horrific bumper car.
Like.
Oh man, that is just not a warm and fuzzy Oh.
I love watching videos of that. It's it's so creepy and like usually, so I have to admit, even though I'm a biologist and I might take my biologist card away for saying this. I find spiders a little creepy. I said it, but I almost feel bad for them when I see them getting parasitized and like manipulating their web building behavior, and then the babies like stick a straw in the back of the spiders and and it's it's kind of creepy. I feel bad for spiders sometimes they have my sympathy.
And you know, if we could have those wasps on the podcast and we would ask them, like, how do you feel about zombifying those spiders, they would answer with the same cold, calculating quickness that you answered when you said you would chop me up on the podcast. There would be like, no problem, let's do it.
Yeah.
Well, so, fortunately for me, I am a low on introspection ability, so I'm not gonna think too hard about what that says about me. But I am super glad that I am not the kind of organism that wasps can manipulate. Life. Is good being a human, or at least being a human in North America.
Until those alien wasps land here on Earth. And it's a regular trope in science fiction that if you go out into space you might catch some sort of weird alien virus which takes over and infects the entire biome, polluting the Earth and demolishing life on Earth. Or if we land on Mars, we could accidentally pollute Mars with some sort of Earth based microbe. This question of keeping things sterile, of keeping things separate is a standard issue in science fiction and also in real life life space missions.
Yeah, we go to great lengths to try to make sure we don't do what's called forward contamination getting Earth microbes out on Mars. And then we were very careful to make sure that you know, when the astronauts came back from the Moon, there was no backwards contamination. They didn't bring any microbes back from the Moon, and so far I think we've had pretty good success. But if I had to bet, I would bet some of our extremophiles have made it to Mars. Do you know, Daniel has anybody, Uh, surely someone's looked at that.
I know that there are Tarte grades that crash landed on the Moon in that Israeli experiment gone bad, and they're probably busy building a colony up there and planning to return with weapons. Yeah, that's pure speculation, of course. Yeah, I feel like I have to say that, since this is supposed to be a heavy science podcast, anytime we say something silly, I want to make sure people know when we're joking. But in terms of sending things to Mars, you know, we have sent stuff from here to Mars, and we have done our best to cleanse it of microbes. But my wife is a microbiology just and she always tells me it's essentially impossible to remove microbes. I mean, you will find microbes in every environment on Earth because there's always some little critter capable of eating whatever poison you're using to cleanse it of microbes. So I'd be very skeptical that our landers have no microbes on them. So since I happen to be married to a microbiologist, I thought it'd be fun to ask Katrina about it directly, and so I did. So. Welcome to the podcast, Katrina, Thanks very much.
For joining us, thanks for having me.
And thanks for contributing your biochemical expertise. Oh boy, So my first question is what are the chances that we have already polluted Mars and the Moon with microbes from Earth?
What a great question, And you know there are teams of people who are devoting their life work to figuring this out. So you know, you're asking me as a bystander to answer that question. But there have been some fascinating experiments where people, for example, have found that up at GPL in Pasadena, California, they use these really stringent cleaning reagents to try to remove all the microbes from the surface of the spacecraft, and they find that there are microbes that can actually eat the most difficult cleaning reagent you can imagine. It's like bleach yum carbon source. They'll eat that. So what are the chances that one of those microbes that survived JPL's most atrocious molecules they could think of to kill all the microbes and then also survived getting out of the atmosphere of Earth and the transport to Mars. What do I think the chances are. I think it's possible. Yeah, I'm not saying these are like happy dividing cells of microbes. It's just that microbes have, first of all the most diverse strategies you could imagine, so there's every time you got an idea, they've got a million more. And then they can form these very dormant sporelike or spore particles that basically, you know, squirrel away and hide their DNA inside of like many, many, many layers of protection. So I think it's very possible that something in that type of form. Ironically, the attempts to clean the spacecraft could actually select for microbes that are really extra tough, and therefore they would have a better chance of having made it to Mars. Now, I'm not saying that when they get to Mars then they're going to be like stretching out, jumping in the pool, having a great life. I mean, they're still going to be stuck in their dormant state. But is it possible that if you like brought some water to Mars and then it could like wake those bugs up. You know, that kind of thing could happen.
Yeah, But so I guess the second question is if it can. So it would need to survive the chemicals, the vacuum of space, and then find something to eat on Mars, and that's a lot of hoops to jump through. You'd need a lot of variability in the microbes that make it to Mars. But you know, if Jurassic Park taught me anything it's that life finds.
A way.
Exactly. Katina is always telling me, like you pick up a scoop of like boiling acidic water near some vent, you'll find like end of the Nine bacteria in every cubic centimeter. Or if you look at some satellite we're sending up into space, you'll find microbes on the outside that eat the bleach they were using to kill the microbes. But you're right, those microbes have survived that environment. That doesn't guarantee that they're going to be able to survive any arbitrary environment. These extremo files are evolved to live in their particular niches.
So should we stop trying?
I think we should just give up on the whole field of biochemistry.
I mean, that's what that's what I think, That's how I felt when I was in college.
No, I think it is important that we try to separate these things. I mean, imagine we land on Mars and we discover microbes there. We want to know are these Earth microbes or not? And even if they have Earth like DNA, we want to know did these come from Earth? Or maybe all of life on Earth came from microbes on Mars that were blasted off the surface. That's an actually legitimate, non joking scientific theory about the potential origin of life on Earth. So we want to know if we've infected life on Mars.
So I know that we we have bits of like Mars that have been blown out into space, and I think they've landed and like being able to find them in Antarctica. Have we looked for alien microbes in those and found anything yet?
Oh, we definitely have looked for alien microbes, And a few decades ago there were scientists who were confident they had found them. They saw these little microtubules, and even President Clinton made this huge announcement, like on the lawn of the White House, that we thought we had found life on Mars. These days, though, we have other non life based explanations for those formations, so people are pretty convinced that's not evidence for life on Mars. But you know, we've gotten like a few rocks from Mars that we could study here on Earth, and so it's a pretty small sample. We're hoping in the next decade or so to do Mars sample return. Would they pick up rocks from the surface of Mars and send them back here to Earth via some ridiculously complicated Rube Goldberg set of devices, But we're all excited to study those and maybe define microbes there.
That would be exciting. I hope we can contain them and they don't take over our minds.
But we can also think beyond our solar system and wonder what about microbes on planets around other stars? Do we need to take the same sort of considerations about avoiding polluting exoplanets or maybe we should turn the question on its head and on purpose pollute those exoplanets with our kind of life.
You know, I feel like maybe we shouldn't have two scientists talking about this, we should have like a philosopher slash ethicist. But we've got what we've got, So what's up. We don't have anybody with an ethical compass here, so let's plow forward with this question.
But fortunately we do. We got a question from a listener, Haley, who is nine years old, and she's young enough to have sort of like an intuitive philosopher's heart and sense of ethics at least, and so she wrote in with this question him.
My name is Haley, I'm nine years old and today's my birthday. I was actually wondering if human wanted to live after us was gone, can't you put like microbes and bacteria on a different plan and let them evolve there. And I was wondering, do you think astronauts accidentally bring little small form like life forms to out of Earth and put them somewhere else, like on their clothes or the rockets by accident?
Thanks Hailey, those questions are so great and happy belated birthday.
And how sad is it that we have to rely on nine year olds to be our ethical compass?
Yeah?
No, I think when my kids grow up, it's gonna be uh, it's gonna be everyone for themselves here.
So I thought this was a really fun question, and I started looking into it, and I discovered that there's a whole project, a whole group of people with specific plans and ideas to do just this, to send our microups, our bacteria two different planets around other stars and to see them with life.
And is the goal so that you can make those habitats more hospitable if humans ever decide they want to move there or are they just doing it like as a fun you know, and end equals too for like the possible pass evolution could take.
You're asking me if they're being responsible or if they're just like mucking around out of curiosity.
No, they're pretty clearly mucking around, but I want to know how they justify the exercise.
Well, that's exactly what we're gonna be talking about today as we answer the question could we seed exoplanets with basic life?
Well, we should see what the listeners have to say.
Thank you very much to our group of listeners who answer these random and sometimes weird questions. We love hearing what you have to say and hearing your voice on the podcast. If you'd like to be part of this not very select group of lead volunteers, please write to me to questions at Danielandjorge dot com. Everybody is welcome. Think about it for a minute. You think we could seed exoplanets with basic life. Here's what people had to say.
I reckon we could seed life on an exoplanet if the environment was suitably similar to Earth and there was some kind of energy source for the life to capitalize on. I imagine it would require a little bit of engineering of the life unless we got very, very lucky with the environment.
I believe it may be possible to seed exoplanets with life. However, I don't think we're anywhere near that capability were probably many centuries, if that millennia away from that.
I think that if an exoplanet has no existing life, then seeding life should be possible. But if there's anything there already, then the differences in proteins and whatever else it may have developed there would mean that it would be pretty unlikely without wiping out whatever was their first.
I think we could, although precisely sending a rocket to an exoplanet would be really tricky. But should we Maybe while trying to seed life we may end up disrupting already existing ecosystems.
Yes, I think we can if the exoplanet has the right habital conditions, and you could maybe put the organism of the life on the planet. So I think yes.
I was impressed by all the different angles the listeners came up with to address this question, like, well it's really far away, is that going to be a problem? You know, what would the environment need to be like for them to survive? Lots of cool ideas from the listeners on this one.
Yeah, exactly, lots of different scenarios. Can we get it there? Would it survive? Why should we even do it? And so I think we should start with your question there, Kelly, But like, what is the motivation here exactly? Like, why would you build a little rocket, put a bunch of bactery in it and send it to an exoplanet? What exactly is the goal you're trying to achieve?
I mean, so, I personally am a big fan of life, and I'd like there to be lots of life and lots of biology everywhere. But I feel like it's complicated when you get to adding biology to places that it doesn't necessarily belong. I don't like invasive species very much here on Earth and like less of that. So are we like doing the ultimate experiment in invasive species?
I think there are lots of possible angles here. I think maybe the most generous motivations are just the ones you expressed, Like life is awesome, let's have more of it in the universe. So imagine you could find some currently sterile planet where there is no life, and your confident life would not arise naturally. Why not see you with life, turn it into a petri dish, see what would happen, and potentially creating biomes that might be habitable for humans in the deep deep future. Now, way, you wouldn't be displacing any current life so you don't have to worry about the ethics of like invasive species and colonialism.
But so that assumption is a really hard one for me to accept though. So, like, you know, we are not even one hundred percent sure that there's no life on Mars. You know, it might still be in like the lava tubes or something sort of like hiding out. So it's even harder for us to study far out exoplanets. How could we ever convince ourselves that a planet is sterile and definitely doesn't have life when we only know what life looks like on our planet, and we can't even tell you if there's life on the planets in our Solar system. So I would have trouble believing we could ever get certainty about that assumption. But what do you think?
No, I agree with you, and it sounds like the set of for a science fiction novel where scientists get humbled because they didn't understand what life could be then they marched forward with their hubrisk too quickly. I agree, we don't know what life could be like in the universe, so it's hard to be certain that any planet really is sterile. It's also basically impossible to be certain that a planet will always be sterile. What if life was going to evolve next week and then you showed up with your zillions of microbes and you now made it impossible. That's not something you can ever probe, right, especially because we don't know how common life is and how likely it is to be created from non living environments. So it definitely would be taking a gamble. But I think the motivations are the ones we expressed earlier. It's just like, wouldn't it be nice to have more life? Imagine if we are the only life in the galaxy and there are all these habitable worlds out there with nothing on them. That does feel like kind of a waste.
It does, And you know, some of my favorite life is a life that I can eat. And so after the break, let's talk about whether or not we can create essentially grocery stores on other exoplanets in case we ever decide to go shopping there.
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Okay, so we all agree life is awesome, and as long as we're not wiping out other life, it might be cool if there were more life in other places and we could sort of see what kind of amazing biodiversity ends up being created in new environments. But let's talk about being able to eat that biodiversity. So, say we were seeding other planets in case humans ever come along, what do you think the chances are that you see the planet, Like, how long do you need to wait before you can harvest it?
Yeah, that's a great question because I think you've pointed out to me many times, and he's described in your upcoming book. If we do land on another planet, we need to find some way to be self sufficient. You can't rely on like shipments from Earth forever, which means you need to be able to create your food locally, which means you need like a whole biome. You need like plants, and you need microbes. You need all this stuff to create your life, and that's difficult to arrive with. So it'd be wonderful if you showed up and there's like plants or at least microbes, or you know, the basic foundation of your ecosystem that you could build your grocery stores on top of. And so in a few minutes you'll hear an interview I did with a microbiologist where asked them essentially that question, like how long would it take to go from injecting bacteria into an ocean to showing up and finding redwoods and dinosaurs, you know, things that you could hunt and climb around on and eat. And so you'll hear him say it's a very, very long time. It's not something you could expect to do in a million years, or maybe even in a billion years. But you know, on this podcast, we are very forward thinking. We're not just planning for our children and our children's children. We're planning for the deep future of humanity right.
Infinite time horizons. Nothing here limits.
Us, which means we can ask for infinite budgets, right, I mean, because like a dollar today is worth so much more in the future. But I think the picture you should have in your mind is the Earth is the only place in the galaxy with life, or one a few places. If li if in the galaxy is rare and it takes a long time to develop, then it seems like an attractive idea to take a little bundle of our microbes, send it to another planet, have it developed life there, because then it would be more life in the galaxy. And also, as you say, it would be the kind of life that we can eat, which is our favorite kind of life. Because you know, even if you show up on an alien planet and it has some kind of life, it's not guaranteed that you could eat it.
Well, I don't necessarily even though it's guaranteed if you could eat it, if it was growing somewhere else, you know, it's not safe for us t eat all the life on Earth. There are definitely mushrooms that you ought not to eat, for example. You know, I guess the question would be like how often do you see the planet and it doesn't take How often do you see the planet but you come back and it's filled with toxic mushrooms or something like that. And so you know, I think there's lots of ways this could go that might not be exactly what you want, but I think all of those ways would be interesting, would teach us something cool if I can ethically, you know, jump the hurdle of feeling comfortable with this experiment.
And you raise an important point earth, which is like, how do you know which planet is a good candidate for sending your microbes? Which planets might have the right conditions, or which planets might be sterile? And so there's a group of folks it's called Project Genesis that have actually thought this through and worked on a little bit of the engineering to make this possible.
Well, tell me more about that.
The idea is to do it in two stages. The first is to send out a bunch of probes to find good candidates, to gather data and beam it back. So the first wave is like, go out there and find planets in the galaxy which might be good candidates. And then a second wave is to actually send the microbes. And this is important because the first wave can be a lot faster than the second wave because the first wave doesn't have to stop at the planet. You can just do like a quick fly by and see these.
Planets and then shoot the data back to us.
And shoot the data back. And this has to do with the physics of interstellar travel, right. All of these stars, even the ones close to us in the galaxy are pretty far away, Like the nearest star is like four light years away, and the whole galaxy is one hundred thousand light years across. So getting from star to star it takes a long time because it takes you a long time to accelerate anywhere near the speed of light. So even getting to the nearest star could take you thousands of years, especially if you have to bring with you all the fuel that it takes to accelerate, and the more fuel you bring with you, the more fuel you need because you have to accelerate all that fuel. See you very quickly have extraordinarily expensive rockets.
So even that first pass is not going to get done in our lifetime. And I can imagine it being super frustrating to like put a bunch of equipment on there, and then five hundred years later you're like, oh, we wish we had put there's other piece of equipment on there. But I guess you'd make do with what you had. Are there options that don't require just like ridiculous amounts of fuel.
There are some really clever options, and we've talked about in the podcast once before. There's this plan for something called a solar sale. The idea is, don't bring the fuel with you. Don't load up a rocket with fuel and then need fuel to push that fuel and fuel to push that fuel. Don't bring any fuel at all, have all the power come from the sun and just have a sail. The solar sail is just a huge mirror and all the photons from the Sun bounce off of it and give it a little push. Photons are these tiny little particles the quanta of light, and they have no mass to them, but they do have momentum, which means when they bounce off of something and go the other direction, they give that something a kick. Like when you're standing in the sun, the sun is literally pushing on you with all those photons. It's a very gentle push, which is why the sun doesn't usually knock you down except in southern California in July, but it is there. And if you had a very lightweight spacecraft and a very large saale. You could accelerate up to near the speed of light pretty quickly.
That sounds like it's even faster than the method that uses fuel.
Is that right, Yeah, exactly, it's much faster than the method that uses fuel. The disadvantage is that there's no way to slow down. Like this thing can accelerate up to near the the speed of light and then it can whiz by your planet very quickly. But it could take some pictures and it could send you some information. That's why this first phase is just information gathering and then beam you back the data of course at the speed of light. So this first phase where you like go out and look at planets, you say, like is there oxygen on them? Is there water on them? What is the basic environment? Like this could be a very quick survey.
Okay, So if you're doing these surveys, what kind of things are you looking for? I assume oxygen. Well, I mean there's bacteria that don't require oxygen. But I guess if the plant is you're seating it for food, you're gonna want there to be oxygen for us. So probably you want a planet with oxygen.
That is the first and the hardest question, Like do you want planets with oxygen or without oxygen? And it's interesting to think about, like where planets do get their oxygen. Are their planets out there that are sterile but have oxygen, or is oxygen purely just a product of life? And it's interesting because actually most planets do have oxygen on them very very early in their life cycle. Most planets are made with water because water is everywhere in the universe, and in the early phase of the life cycle of a star, they tend to emit a lot of ultraviolet radiation. This is part of their life cycle called the pre main sequence, like before they settle down and really just doing all their steady burning effusion, they emit a huge amount of ultraviolet radiation which can break up that water and produce oxygen. So very early in the life of a planet they do get some natural oxygen without any life right, So you can get planets with oxygen on them. Problem is that for a lot of stars this early phase is not very long. It's just a few tens of millions of years, so it doesn't make very much oxygen. And because you're blowing off so much solar radiation, a lot of the atmosphere of a planet can just get blown off, and this is what happened to Earth. We had a little bit of oxygen made early on through this UV light from the Sun, but then the Sun basically blew away our entire atmosphere that was the one that was formed with the original planet.
Whoops, we want to send Do we want to send photosynthesizing organisms?
Then well it's an interesting question, right Like on Earth, life started without any oxygen because the atmosphere was replaced by volcanic outgassing which got nygen and CO two, and then photosynthesizing organisms did create oxygen. But it's interesting because a lot of biochemists tell you that having oxygen makes it harder to form life, like a lot of the chemical building blocks of life couldn't have formed if you had a lot of oxygen in your atmosphere. That the anaerobic procedures are actually more important and they're inhibited by the presence of oxygen. So if what you want is to start life on a steril planet, you probably don't want oxygen. But if you want to seed it with life like hours, then probably you do want to find oxygen rich planets because they're more conducive to our kind of life, and they're probably sterile because the oxygen is like poisoned to those early forms of life.
How do you know that the planet you're seating hasn't like progressed as far as Earth and that's why it's got oxygen? I guess because your flyby was that accurate.
Yeah, on the flyby, you're going to do more than just test for water and test for oxygen. You can also look for methane, for example. Methane and oxygen together are a pretty good signature of life. You know, you can look for phosphine. It's a whole really difficult question of like how do you know if there's life on that planet? But I think in general, looking for oxygen rich planets that don't have obvious signs of life is a good target because oxygen tends to prohibit the formation of early life. And it turns out it actually is possible to have planets with lots of oxygen that isn't produced by photosynthesis.
And where do we get it from?
So there are a few different ways that planetary scientists think that it's possible to have a bunch of oxygen on your planet and not have it be blown away in the early life cycle of the star and not have it come from photosynthesizing life. There's a few different configurations that at least their models tell them this can happen. In Like, if you have a planet that has a huge amount of water, like a water world, then all that water will put pressure on the crust of that planet, which basically shuts down the geologic activity like all the plate tectonics and the volcanism that we have, and it slows down the weathering and the melting of the rock. Both of these things absorb oxygen from the atmosphere, and so if you have a huge amount of water, you can shut down these sort of like oxygen slurping mechanisms. Like you know, rocks out there on our planet have rusted because they have oxygenated. All the weathering of rocks on the surface of the Earth has slurped a huge amount of oxygen out of our atmosphere. So if you have a planet where you basically suppress the oxygen slurping mechanisms, then you can maintain some of the oxygen in the atmosphere. That's sort of like one mechanism to make an oxygen rich exoplanet without life on it.
So to get an oxygen rich exoplanet without life, you can do it by having tons and tons and tons and tons and tons of water. Can you get more dry versions or does it always have to have loads of water?
Yeah, exactly, you can. The sort of desert planet can also do that. If you have a little water but not in zero, then you end up with like a solid surface and a lot of steam in the atmosphere. It gets very very hot and all the water becomes vapor. It provides this like big reservoir of oxygen in the atmosphere, and then the sunlight breaks if the water molecules, the hydrogen floats off to space because it's very light, and the oxygen sticks around. And if the planet has like a solid desert surface, it can't weather, it can't absorb that oxygen, so then the oxygen stays in the atmosphere. So you have either like water world or a desert planet with like a steamy atmosphere.
All right, Is there anything in between? Or those are the two ways you get high oxygen environments.
There is one other speculation. If you have a planet that has like a very high initial ratio of carbon dioxide to water, then you end up with a runaway greenhouse effect, sort of like Venus. It gets super duper hot and you have no oceans because all the water is turned into steam, and you have no volatiles in the planet's mental because it's too hot. These voltuls would do the same thing of like sequestering all the planetary oxygen through chemical reactions. Instead, the voltils are now in the atmosphere where they're unable to remove the oxygen. They're having a really significant runaway greenhouse effect. Is another way to suppress some of the oxygen slurping mechanisms that would normally remove oxygen from an atmosphere. So either you have a water world or a desert planet, or you have like a crazy Venus greenhouse effect.
Well, frankly, i don't want to live in any of those environments, so I'm hoping whatever microbes we dump makes everything a lot nicer, much longer. After Let's take a break and then we'll talk about one other nice option for where we could be seating our microbes.
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Okay, so there's one other nice option for places we could see maybe maybe there's more than one, but one that we're going to talk about today, and those are planets that have these short windows of time as they're sort of developing and going along where they might be a nice place to seed with earthy microbes. Could you tell us about that?
Yeah, I remember. The big idea is to look for places where our life might survive, but life wouldn't grow on its own, where we're not displacing native life like original species. So one idea is oxygen rich steroplanets because the oxygen prevents life from arising. The other is to look for places where life doesn't have time to arise, like it might be that there's enough time for us to seed it with life, which could then take off, but there aren't like the billions of years it would take for life to start on its own. An example of that are brown dwarf systems. Brown dwarf is a star that's not hot enough to fuse the way that our star does. It doesn't have enough mass, so there's not enough internal temperature for fusing to kick off. So they call these sometimes a failed star. They're just big blobs of hot gas and they're hot, but they're not fusing. They're not glowing. Right. This does provide some temperature to create a habitable region for your planet, and it could remain habitable for like a few hundred million years or a billion years, but not like a long time the way that our Sun and our Earth has many many billions of years as a window. So the idea is to look for brown dwarf systems where life could survive, but maybe it doesn't have enough time to develop on its own and seed planets in those systems. That's a place where like our life could again survive, but we wouldn't be displacing any native species.
But so then we would need to move our life somewhere else. I mean, I guess it would have millions or billions of years, and so it would have some you know, time to run its course. But I mean, is that enough time where we could imagine that something we could eat could have developed, and that that would be a useful run for the experiment.
Yeah, exactly, So you send our life there, and it has enough time to flourish and develop and do something before we arrive and set up our grocery stores.
Okay, I I feel like there's still a part of me that feels like it's enough time for our seated microbes to do their thing. That should be enough time for life to potentially arise on its own there. So I'm not one hundred percent convinced that we wouldn't be snuffing out some other possibility for the start of life on another planet. But am I missing the point?
No, you're not at all. And I totally agree. All these calculations assume that life takes a long time to start, and if it doesn't, if life starts pretty quickly when there are good conditions, then all these places potentially could have life already or could start life any moment, right, And if you see them on a Tuesday, you could be displacing life which would have started on a Friday. And so before we do this, we definitely need to understand that a lot better before we're confident in saying like, oh, this is a sterile place and it's unlikely for life to arise anyway.
Okay, So let's assume that we've convinced ourselves we found a sterile place that we feel comfortable seating microbes. How do we get the microbes there? I assume some of the methods that we used to survey could also be used to deliver microbes.
So it's a great question how do we deliver the microbes? Right? Say you actually have this little blob of stuff and you want to send it to a planet around Alpha Centauri or something where we talked about earlier. The solar sale is great for getting up to high speeds, but it's not so great for breaking. You don't want your microbes to hit the planet at like ninety five percent of the speed of light because then they'll just like core sample the planet. Right. They need a gentle landing if you're going to disperse them, sprinkle them on top of the ocean. Right, So somehow you have to figure out how to slow down. You don't just want to accelerate and zoom through the system. You want to arrive at a gentle speed.
How do you do that?
Yeah, it's tricky, but there's a really cool technology called magnetic breaks, which are very similar to a technology that you and I talked about in that science fiction novel Orbital Cloud. Remember that they had this technology in that book to maneuver satellites by using the Lorentz force. They had these long space tethers, these long wires. If you put a current on the wire, it would interact with the magnetic field of the planet and put a force on the object. It's a very similar idea here. The physics is fundamentally the same, though the mechanism is a little bit different. What you do is you bring a loop of wire and you make a current. That current makes a magnetic field, and you can use that magnetic field as a break because space is actually filled with stuff that you can push against. Because the Sun is not just putting out photons, it's putting out protons. Part of the solar wind are these charged particles, these protons flying through space, And as you approach this distant system, you can turn on this magnetic field which will push back against all of these protons in a way to slow you down.
Could you turn on the magnetic brakes from Earth? Like, how do you make sure the breaks don't turn on too soon?
I got no breaks, No breaks exactly. No, It's important that you time this right. And yeah, you could turn this on from Earth, or you could preprogram it to know where it is, or you can detect a certain level of protons. There's lots of various ways to turn it on. But yeah, you could send this thing messages which would catch up with it because it's not flying at the speed of light, and so your photonic messages from Earth could always catch it. Now, unlike a solar sale, which people have built and tested, magnetic breaking is a little bit more theoretical. Nobody's ever built one of these things as far as I could tell, and demonstrated that it could actually work out there in the environment of space. But in principle, we have some ideas about how to do this, how to send something there really really fast and slow it down in time to enter the system.
Okay, so let's assume that we can send something out to our chosen exoplanet and we can stop it so that we don't accidentally core the planet. Like, how do you pick which microbes you send?
Yeah, that is a great question. What do you send? How likely it is to survive? You send one thing, you send ten thousand different things. You send more of one than the other. How does this all work. What do microbes need anyway? So I didn't know the answers to these questions, so I called up a friend, Will Ratcliffe. He's an evolutionary microbial biologist at Georgia Tech, and he studies the evolution of multi cellularity, Like how did creators go from individual cells to working together as single organisms?
You have such interesting friends. Let's hear the interview.
So here's my chat with Will Ratcliffe. All right, so then it's my pleasure to welcome the podcast Professor William Ratcliffe. Will welcome to the podcast. Thanks very much for.
Joining us, Thanks for having me.
So Will, we are talking about dropping a load of life on some alien planet, some exoplanet, and I'm just wondering, like, first of all, what are the chances of microbes surviving If I take a bunch off I've scraped out of sewage here on Earth or you know, from underneath some trees or something in a forest, and I launch them to an alien planet. Are they just going to dry up and die? What are the chances that they can survive?
So the answer to this, I think really depends on the existence of a few things. You need liquid water, There's really kind of no getting around that. If you have an exoplanet that doesn't have liquid water, ideally on the surface, then it's going to be an uphill battle for life. You might have things which persist but don't flourish, but if you have liquid water, then it becomes a question of what kind of energy sources and what kind of carbon sources are available for that life. We're used to life that sort of makes a living largely either eating other things, which we do right. We take large chains of carbon and break them down and get both of our carbon, which is what we used to build bodies, and our energy, which is what we used to power those bodies, from those big chains of carbon. But there's actually a lot of different niches that life has sort of evolved to take advantage of dissipate energetic equilibria and build bodies with carbon in different ways. One that's really common and I think you know common in the universe and really impactful is light. So you know, photosynthesis. So being able to use light for energy is a really common way of making a living because there's a ton of energy in light and it's relatively straightforward for organisms that have evolved the ability to use it to just put it to work powering cells.
But didn't we have life on Earth for millions of years before we had anybody taking energy from photons.
Yeah, that's a good question.
It's actually it gets really difficult to infer back that far. So we likely had photosynthetic behavior pretty soon after the origin of life, although again it's difficult to really see back beyond a couple billion years. By two point one billion years ago, we had had so much oxygen pumped into the atmosphere on Earth that we oxidized our atmosphere and we have you know, we basically couldn't absorb and react away any more of it. But life arose around three and a billion years ago. But you're right, there's other ways to make a living that don't depend on light, and in fact, if we if we look at those, those are things which are probably pretty common in the universe as well. So you know, the main way that metabolism works is by taking something which is at a high energy state and reacting it into a lower energy state and using the energy that's released to power metabolism. These redox reactions are common. There's many different ways to do it. A simple way is to take hydrogen right and sort of burn it with oxygen and burn it into water that releases a ton of energy and that can be used to power metabolism. You may not have oxygen, I mean hydrogen. That's really common in the universe, So I think we can assume that there may be some hydrogen around, right. You may not have oxygen, however, I'm one of these planets. Although I will say, on a planet that has a surface water, it's not that unlikely to think that there will be some oxygen every now and then. And that's because if there's light, light will take water. It'll break it apart, you know, ultimolt light will break it apart. The hydrogen will escape into space, and you'll be left with oxygen, which is persistent depends on whether it reacts with things.
But you can have oxygen around.
So you're saying, we basically need liquid water, we need some light, and we need some carbon and some hydrogen, and then probably the microbes will be happy munching away pretty much.
And it turns out that we can even make it less restrictive than that.
You can take light off the table, although I think you know, since planet's usually around stars, light's usually not.
Off the table, but you could take it off the table.
And if you have hydrogen or if you have iron, those are also very common, very effective sources of generating the electron flow during a redox reaction that can power life. So there's life on Earth that can literally rust iron and grow using the energy that comes from that. That same life can take carbon dioxide and fix it, meaning turn it into longer chains of carbon, and so you can basically if you have carbon dioxide and you have iron, or if you have hydrogen and carbon.
Dioxide, you are good. If you have light, you are really really good.
And if you have oxygen light iron and carbon dioxide.
Is chill, you can easily have lighted well.
As a physicist, I worry about other things like levels of radiation. You know, if this thing is getting like impacted by huge numbers of cosmic rays, I worry about them getting shredded. On the other hand, I have in my head my wife's voice, and she's always telling me that life survives everywhere. You know, they find it on the outside of the Space Shuttle and they find it. You know, it's basically impossible to fully sterilize anything inside Chernobyl. You know, you find things that are rad hard. So do we have to worry about these creators being fragile or we're pretty sure if we have a big enough sample that some of them are going to survive.
I think it's not a big worry. If you have a large sample, you'll have things that survive. Plus you could have them in habit environments that are somewhat protected. You know, Hydrothermal events on the bottom of the ocean, for example, will buffer you from a lot of stuff. And then organisms can evolve mechanisms that make them much more robust to the damage to DNA that's caused by high intensity waves and particles. So, you know, a lot of organisms like tartar grades are often touted as a cool example of something which is robust to DNA fragmentation.
They've evolved a lot of.
Cool mechanisms that can take DNA that's been busted into a bunch of small pieces and reassembled in a pretty accurate manner.
All Right, So say you're tasked with developing this payload. We're going to drop it on some random alien planet you know very little about, just because you've seen maybe some spectroscopy from its atmosphere. What cocktail do you recommend sending, I mean, should we just scoop up a sample from a local forest? But does it really matter if they're all so hardy.
I think it does matter in that a local forest, the surface of a local forest is probably a very different environment than what you're going to find there, and it's an environment that is not wet.
Right.
I think we're going to have our best bet with something which targets oceans, because oceans are large, oceans are relatively stable, and if let's hope that this planet has surface water that's liquid and within those oceans, I think I would have a mixture of things which inhabit both the surface and our phototrophic so things which can photosynthesize using light, and things which inhabit like sea floor niches where they can do chemical chemical autotrophy, where they would be basically breaking down hydrogen using hydrogen sulfide as an electronic acceptor doing things which allow them to make a living that is completely independent from a light based ecosystem.
So then what do you expect we might get, Say we drop this thing on an alien planet and we come back in fifty million years, or our descendants eventually make it out there on slow colony ships. Are we going to end up with just like a frothing ocean filled with microbes, or are we going to show up and there's going to be dinosaurs in redwoods, or you know, some alien version of these things.
Fifty million years is pretty short in the scheme of things, so I think you're looking more at a frothing ocean filled with micros, although they may terraform the planet in the sense of creating a foxygen. You know, the amount of oxygen that we have in our atmosphere twenty percent of our atmosphere, that's all coming from life, right, that's all coming from photosynthetic organisms. And so if this planet doesn't have life already, if it's a steroiplanet, there won't be much, if any, oxid available. Like the amount of action that we have is because of life. And so I think if we could get you know, very photosynthetically active ocean microbes, it might take a little longer than fifty million years, but you could terraform the planet in a way that would probably result in more of an aerobic atmosphere or something which we're more happy with. But to get something like dinosaurs and redwood trees and stuff. I would probably actually jump the gun a little bit here and see the world with more highly, more derived organisms than just these bacteria which are hardy, which can live. You know, bacteria are like the ultimate metabolic you know, tool kit masters. If there is an energy source to be dissipated, there's a bacteria or an archeia, a single celled organism that has evolved to dissipate that. You know, there's bacteria living miles deep in rocks eating only hydrogen. It's outstand you know, they might divide once every thousand years. It's it's really cool. But these types of more complex organisms, generally speaking, these multi sail organisms that we can see that have you know, complex morphological features. They evolve from eukaryotes, which are a different kind of organism that's actually the result of a symbiosis between a bacterial cell and an archel cell, and that symbiosis started on the order of two billion years ago. And these organisms have compared to bacteria, they have a lot more complicated subcellular features. They have their DNA encased within a nucleus, they have more complicated mechanisms for generating and moving proteins and they have many more opportunities for within cell gene regulation. And it's within this more complicated kind of cell that you've gotten the types of multicycular organisms that we know and love. Plants, animals, fungi, dinosaurs, redwood trees, and in fact, even those lineages which have evolved pretty sophisticated forms of multicecularity, it took them quite a while to do that. So animals have been around for you know, on the order of at least six hundred million years. Plants cropped up around four hundred and twenty million years ago as kind of when they out there start. Fungi I have probably been around for about a billion years, although it's hard to tell when they became multicegular, but it often actually took quite a while for this origin of multicecularty to play out. But I will say, once you give them a toolkit or they have the ability to have cells that remain attached to one another and to specialize in different behaviors and you know, regulate that specialization through communication or other bioelectric sensing in response mechanisms. Once they have those toolkits for how cells grow into bodies and specialize and undergo morphological novel morphological function. They can diversify very quickly from that starting point. So I think what you'd want to do is like see that world with maybe relatively hardy, relatively simple plants, animals, and fungi, and then let those things diversify into the various ecological niches that they find, although you might actually have to do a sequential now that I think about this sequential seeding. Hit them with the basic stuff to get you know, a carbon rich ecosystem going, and then to send the more complicated stuff, you know, a couple thousand years later.
So what do you think is the most complex form of life that might survive this kind of trip. I'm imagining this thing is like frozen or desiccated and then dropped into the ocean with basically nothing, and we hope it just sort of reconstitutes itself. You can't do that with like a dog, right or a tree. So are we seeding this planet with tartar grades to come back fifty million years later to find the human size intelligent tartar grades?
That's a fantastic question.
So freezing things for interstellar travel, like a lot of smaller organisms, there's probably a way to work that part out of that too much difficulty. You can freeze, you know, you can't freeze a fly, but you can freeze you know, a number of smaller animals, certainly tartar grades, would have no problem being desiccated and shipped around the universe. But I don't think that they're going to become you know, large and complicated. They make their living basically sucking up bacteria.
Plants.
I think I would take advantage of resting stages explores, inferns or you know, heart very very durable seeds of angiosperm. So that being said, I don't know what, if anything, could survive these extremely sterile conditions that we would find ourselves without a new planet. I mean, I think bacteria are really like they should do fine. You know, if you throw enough stuff, enough different types of bacteria, with enough different forms of metabolism at a blank slate environment where there are energetic, you know, conditions, energetic equilibria to be dis equilibria to sort of be taken advantage of and be used for energy, you're going to get something which grows on that. But plants, animals, fungi, those are all things which largely have evolved in the context of an already pretty rich ecosystem of other organisms, and they're highly dependent on those other organisms to make their living. I mean, plants you might be able to get away with in the sense that they are mostly self sustaining, photo autotrophic organisms that are growing on light, water and minerals. But even plants are really specialized on growing on land like plants are basically you know, we talked about, oh, the invasion of land. Really it's the invasion of air from a marine Analogay, that was the difference called part plants. So I think you could probably if I was gonna throw anything in there that was that was larger and more complicated, it would be something like a seaweed, right, because they're they're phototrophic, they're they're getting their energy from the from the sun and minerals. There are many mutualistic interactions that they have with other organisms. But I'm sure you could find something which doesn't depend on those and can grow azenically. And then once you have macro algae growing, they create a habitat for many different organisms, lots of animals, for example. So if I thought about this more, maybe well, you know what I would do I'm not sure how you would ship this around the universe, But have you ever seen those fully enclosed little ecosystems that have some algae and some shrimp. I think they're Hawaiian and they can live like in a completely enclosed, sealed glass sphere for decades, where that you know, basically you have this nice balance between the oxygen that's produced by the alergae and the food that's created and the shrimp which consume it and create carbon dioxide which the algae use. It's pretty cool. So something like that, maybe some small and vertebrate which is mostly grazier on algae or even eatings, think that might the single style alogae which grow on the surface of macrology and macrology and maybe try to get that established. I don't know about just throwing it into a sterilocean, but if there's a way to sort of, you know, have an incubator where you have a near shore environment or a pond, something a little bit less big then subject to planetary scale weather.
So is this an idea which excites you? You're like, ooh, this would be really fun to see what happens, or is something that terrifies you The idea of you know, polluting the galaxy with our kind of life. You know, is it wonderful to imagine showing up on this planet and having like intelligent shrimp swimming in kelp forests that we seeded, you know, long times ago.
It's more exciting than terrifying for the simple reason that, while we don't really know what the extent of independently evolved the life on other planets is, it seems like the amount of planets that exist vastly as strips the amount of independent origins of life, certainly complex life. And so it doesn't seem to me that planets with liquid water are necessarily a super limiting resource in our universe. And so the opportunity to see how life would evolve, given replays of the tape, right, to see how it would independently go about colonizing a planet, diversifying, I mean you could, it would be It's a once in a lifetime opportunity to see how something which starts over reconstitutes itself, how a bioshore reconstitutes itself.
So you want to turn the entire galaxy into your own lab basically, I mean, you know, I wouldn't say no.
That's the exciting part, but I would say you'd have to be very you know, very confident that there wasn't already existing life on that planet before you went about doing this. I mean, if it truly was sterile, then I don't think that there's a huge amount of downside, But a lot of that depends on how confident you are that it really is a sterile planet. And you know that being said, if this planet's sterile, and it's been sterile presumably for quite a long time, despite being habitable billions of years, it seems unlikely that it would all of a sudden not become sterile in the near future anyway, So I don't know what you're giving.
Up, all right, Well, thanks very much for sharing your excitement and your insights with us. Really appreciate your time.
It's a pleasure.
And of course I checked in with Katrina to see how much she agreed with Will. So then if microbes are so hardy, if we wanted to seed and exoplanet with life, can we just send anything we want or do they need to be carefully chosen?
I think diversity would be a better strategy than like carefully choosing just one strategy. So I think you would be better off. You'd be more likely to succeed by gathering up microbes from a lot of different environments and then sending as many different strategies out there, so you'd get to roll the dice a lot more times. But I think you would want to pick from environments that are already harsh and potentially similar to the place that you're trying to bring the microbes to, so that they would already be adapted. But yeah, if I had to pick between, like, you know, one lab evolving a perfect bug versus just like sampling all of Earth's environments, I would vote Earth's environments.
So I think Will's answer your question is that would take a lot longer than fifty million years to get from microbes to redwoods and dinosaurs and grocery stores.
So I am not going to be shopping at the brown dwarf grocery store. That's a bar.
No.
But you are great, great Kirk Kirkerkreker. Great grandkids might be able to have dinosaur steaks for dinner.
Thank goodness. The future is good. Okay. So, as you may have been able to pick up throughout the course of the conversation, I have some concerns about this idea, though I do find it interesting, So should we do it? Let's end on that. So how about in our solar system? What do you think should we ever do this?
I think it's a hard question in general, but I think that in our solar system it's pretty clear, Like, yes, it'd be nice to be able to live on gamy Mead or on Io. But if we just send our microbes and spray them all over the Solar system in the hopes of eventually having a biome that could support us, we're ruining our chance to answer a much deeper, more important question, right, like how hard is it for life to start? Could life have started in other places in the Solar system independently, or maybe life in the Solar system actually did start only one place, but not on Earth, and then came to Earth. If we sprayed bacteria microbs all over our solar system, we couldn't answer these questions. We'll have polluted our backyard, and I think those questions are more important than grocery stores on io.
I think many people would disagree with you, especially when it comes to Mars, because, of course, if we're going to settle Mars, we are going to be seeding Mars with all kinds of stuff, and depending on how soon we do that, that might be before we even know for sure if Mars has life on it or not. So this is, you know, something that could possibly happen in our lifetime. But do you think that the ethical questions become or have a little clearer answers if we're talking about other solar systems.
Well, I want to get back to Mars actually, because as a world famed skeptic on the possibility of settling Mars, I have to ask you, do you think it's possible to settle Mars and not polluted, Like could we set up some sort of barrier where we have like an Earth region on Mars and somehow avoid contaminating the rest of the planet or is that impossible?
I'm not very optimistic that we could do that. So, you know, Mars has dust worms that blow dust all over the planet, and you know, I think there are microbes that you know, even if you said like okay, no humans are allowed to, you know, cross this line and half the planet is going to be pristine, I think our microbes over time would sort of blow around the planet. And you know, if there's no microbes there, then they're already Then maybe that's not so bad, although the microbes will start changing, you know, like the chemistry of the environment, and that might make Some scientists said, who wanted to study Mars And it's like preserved states, you know, there's a lot of trade offs you need to make when you're thinking about what to do with another planet.
Yeah, it really does seem like we have to decide is Mars a scientific preserve or is it a resource to be exploited.
Yeah, And then the difficult thing is, you know, if the US decides one thing, or in China decides another, or Russia decides another, Like can you get the whole global community to agree on what we're going to use Mars for? And I guess we'll see.
Yeah, and not just governments, right, eccentric zillionaires can start their own Mars colony outside of any jurisdiction. Right. There are no laws on Mars as far as I'm aware.
No, no, no, no, nope. So if Musk wanted to go to Mars, he would still have to like get a permit through the FAA, and he would have to like essentially get approval from the US government, And when you're out in space, you are still the responsibility of some government. So Musk would still be the United States's responsibility. They should be telling him what he can or cannot do out there. So you know, the Outer Treaty is international law that is supposed to apply to when humans go out into space as well. But you know, is Musk gonna listen? That's a different question entirely. And what would be the implications if he doesn't listen? Who knows? Because the US could say no.
More, You're gonna throw them in Mars jail.
That's right. I mean, so the US does have some leverage. They could say we're not sending any more resupply ships until you guys, you know, get your ax cleaned up. But yeah, who knows what muscle do when he gets there.
Yeah, So it's a tricky question here in our solar system. In terms of other solar systems, I think it's related, But for me, the balance tips a little bit in the other direction. Like, there are so many planets out there, I'm fairly confident we could find some that have no life on them that we could use as experiments, or we could use to seed edible biomes for the very future of humanity. Seems to me to be too restrictive to say we can't explore or we can't experiment anywhere in the galaxy.
Yeah, I think if you could absolutely convince me that we definitely knew what to look for and could absolutely determine that a planet was sterile, you know, the evolutionary biologist and me would love to see what happens if you, you know, drop microbes and then come back, you know, six billion years later, what do you have there? That sounds fascinating. It would be difficult for you to convince me that it was definitely a steril planet and we weren't going to be especially when it's you know, in a different solar system. But if you could convince me of that, then I would certainly be interested in seeing this experiment run, not just because I love food so much, but because I think there'd be interesting science.
Yeah, because it would be a huge tragedy if there really was like alien life on that planet and then we sent our microbes and it like wiped them out. What if we showed up and there were like fossils of a dead civilization that we had killed with our equivalent of smallpox.
Oh, that would be awful, and also from like a science perspective, like losing all of the data on like when life actually pops up independently and the direction that that took, as opposed to you know, what does our life do when you put it somewhere else. I think it's much more interesting to see what happens life pops up somewhere else on its own, and then what happens to it. But yeah, so many levels of it being super sad if it turns out we're messing up what's happening on some other planet.
Yeah, if that happens, we should get thrown in space jail.
Yes, yeah, except you know we will have long since been dead because it will take so long to get the microbes there. So I guess our whole species would have to get thrown into space jail.
Yeah, exactly. I think it's an interesting question even if we never do it, right, even if we don't actually do this, it's fun to imagine, like how would it work, what technology would you need? Is it even possible? To me, it's fascinating that we're not actually that far from this kind of technology, like solar sales. We could build that magnetic breaks probably that would work capsules of ocean water which might survive the transit from here to there. That's not implausible like this sort of science fiction. The scenario could be reality in the not far future.
Yeah. We live in exciting times with exciting possibilities, and I hope we make the right choices.
Since we're talking about some big moral choices. I asked Katrina about the should we side of this question, and how would you feel if an alien payload arrived with their microbes hoping to seed our world with their bugs? Would you feel invaded or intrigued?
I mean obviously intrigued, but how would I handle that?
I hope you're listening to that aliens.
Yeah, and CDC. I hope the CDC is not listening to that one too much, actually, But I mean, you would definitely want to do that kind of work in a very careful environment, and we do know how to work with pathogens. It's never perfect, though, I mean that's a whole other conversation. But you know, I don't love hearing that there's smallpox in a freezer somewhere and it's just one mistake away from getting into contact with humanity again, and so not knowing what the health impact or the environmental climate impact of a new set of microbes would be, I would definitely want to tread lightly, but I'd be super intrigued. Oh my gosh, that's a dream to get to figure out how on Earth they how on wherever they came from, they do their metabolisms and coffee themselves, and I mean, that would be fascinating.
I hope you feel like you've made the right choice in listening to me and Kelly talk about this question for the last hour, and I hope that you learned something not just about whether or not Kelly is likely to chop you up, but whether future humanity could and should send microbes to other planets.
I was the scary co host this time. Usually that's your.
Job exactly now. I know what it feels like. Oh my gosh, I'm quivering my boots and I'm glad we're across the country from each other. Thanks very much for joining us, even though you threatened to slice me into pieces.
Thanks very much for having me, for being a good sport when the tables returned.
All right, Thanks for listening. Everyone, tune in next time. Thanks for listening and remember that. Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact. But the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. House US dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last Sustainability to learn more.
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