Short Wave - What Mount Kilimanjaro Has To Do With The Search For Alien Life

Episode Date: March 16, 2022

Understanding how life survives in extreme Earth environments could point to ways life can survive on other worlds. Astrobiologist Morgan Cable talks to host Emily Kwong about how her missions here on Earth have guided two upcoming NASA missions in search for alien life, not in a far off galaxy, but here in our solar system. The Titan Dragonfly and the Europa Clipper missions will each explore an ocean world in our solar system, where scientists believe we could find life--life that may be unlike anything we've seen before. Today on Short Wave, life as we know it - and life as we don't know it.Learn more about the search for life in our solar system in the new planetarium show Living Worlds, now at the California Academy of Sciences: Thoughts? Questions? Pitches? E-mail us at [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. For someone who studies outer space, Morgan Cable has been on some pretty cool work trips right here on Earth. The most unique place I've ever been was the summit of Mount Kilimanjaro. It's called the Roof of Africa. Its altitude is, what, 5895 meters, so it's about 20,000 feet. We camped at the top for four nights, and it was just so incredibly beautiful. Morgan is a research scientist in Pasadena, California.

She's based at NASA's Jet Propulsion Laboratory and studies extreme environments. Environments found in places like the summit of Mount Kilimanjaro. Up there, it's very barren. I mean, there aren't even plants at the top. There's, you know, some rock, there's some ice. And there are things that have been blown up from sort of the Serengeti down below and deposited over time by the wind. And Morgan hacks into that ice.

She wants to see what's inside of it. We are looking for something called biosignatures or biomarkers. And essentially, that is stuff that tells us that life is there or was there in the past. There are things like pollen and stuff like that that's preserved and also bits of bacteria. Certain things that we call bacterial spores. These are the toughest form of life we found on Earth. So tough that they can survive in space. See, as an astrobiologist, Morgan has tracked all over planet Earth to identify biomarkers fit for space travel, from lava fields in Iceland to the Atacama Desert in Chile.

By looking closely at extreme life here on Earth, down to the bacterial spore, Morgan is getting a pretty good idea of how life might survive on other worlds. They're like microbial hitchhikers. They could survive a transfer from a spacecraft or from a meteor or something like that and visit another world. So today on the show, Morgan Cable's quest for extreme life on Earth and how it's helping her plan two space missions, Clipper to the moon Europa, and dragonfly to the moon Titan. Those missions are searching for life in this galaxy right here in our solar system. I'm Emily Kwong and you're listening to Shorewave, the Daily Science podcast from NPR. So Morgan, Europa is a moon of Jupiter and Celadus is a moon of sea. Saturn. Why would a NASA scientist want to go to the tops of mountains on Earth to better understand the moons of these faraway planets? We call these environments extreme environments because they tend

to have one or more properties that make it really tough for life to survive. Sometimes that means it's really cold and the organisms need to spend a lot of energy to kind of keep warm. Sometimes it can mean that they have a lot of salt. And so some of these organisms may need to fight to keep a lot of that salt out of the insides of their cells. And so these kinds of things make it more challenging for organisms to live. And so they'll adapt in different ways to be able to handle whatever that extreme environment throws at them. But usually that means that we don't have a whole lot of big organisms. For example, we don't expect to find whales or something like that,

swimming in the oceans of Enceladus or Europa. But chances are there's just not enough food for a whale to eat, but we're not ruling it out. Wow. That's really a thing to take with you that sometime a space whale might be discovered. But anyway, go on. Well, could you imagine like picking up a whale song in an alien ocean, how amazing that would be? Anyway, I digress. Okay. But yeah, so what do we look for? Well, we, as you know, still, only have a sample size of one when it comes to life. There's one planet we know life exists on, that's Earth. That is. are one example. And we, as scientists, as astrobiologists, try really hard not to be biased by that, because alien life in a different ocean on a different world could be very, very different from

earth life. So we try to take what we call an agnostic view, where instead of looking, say, for the specific genetic code of earth life, instead, we would look for something that would fill that same role. We would assume that any organism in that ocean or frozen in the ice would still need some way to reproduce and have some kind of like instructions encoded like DNA does for us. There are other examples of things we could look for too. Like let's say that this is in a liquid water ocean, well, we might assume that cells in that ocean would still want to have some kind of a cell membrane or cell wall, something to keep their molecular machine. bits isolated from the ocean. The point is that we will look for things that we, that try not to be

exclusively biased by Earth life. Yeah, we're a little too Earth-centric down here, you know. So Dr. Cable, to the best of your knowledge, where else in the universe may life exist? Besides Earth, of course. And how can you even tell that life may exist in a place? So typically it's three things. It's liquid water, chemistry, like chemical building blocks, you know, organic molecules, and energy. an energy source. Okay, so that's your criteria for scanning for possible places for life. Yep, and we call those places habitable worlds or habitable environments, places where life could exist if it was there. I'm a little biased, but the top three for me are Enceladus,

Europa, and Titan, and these all fall into that category of ocean worlds that we've been talking about. These are typically moons of Jupiter and Saturn that have a crust of ice, and then underneath that crust, they have a liquid water ocean. And in some places, like the case of Europa, that ocean is bigger than all of Earth's oceans combined. Titan has a liquid water ocean deep in the inside, but also on its surface, it has a different liquid. It has liquid methane and ethane. So when I give toxic kids, I always talk about lakes and liquid fart and they get really excited. It gets me excited, too. We had an episode on Shortwave a few years ago that I'm going to send you. it's every moon ranked.

Someone went and ranked the moons. And Titan was number one. Yes. Yes. I mean, that's cool. I'm unbiased. What an honest reaction. But they're all cool.

We're in the pocket of Team Titan over here. You're among friends. Oh, my God. Well, I love Titan. But I also love, I mean, Enceladus is spewing free sample from its ocean into space. It's kind of like, hey, NASA, you want to know if there's life here? Just come on by. You don't even have to dig or drill.

just come on. And Europa might have a plume too. So it's like each of these places is so unique and special and fascinating in its own right. And it's important for us to study each and every one of them. It's just a super cool time to be alive and to be a scientist studying astrobiology. Dr. Cable, I want to talk about two missions that NASA has on tap right now, that you're a part of the Clipper mission, which launches in 2024, the Europa Moon of Jupiter and the Dragonfly mission, which hopefully launches in five years and is set to go to Saturn's icy moon of Titan. Let's talk about Dragonfly Titan first. Tell me about it. Oh my gosh. This one is super exciting. So Dragonfly, take one of the big Mars rovers, right?

Like Curiosity or Percy, Perseverance. They're like the size of a car, right? So take one of those, take the wheels off, put skis on, and then give this thing eight helicopter blades. That is dragonfly, and it is awesome. And the reason that we're doing this is because Titan, which is a moon of Saturn, like you said, it is about one-six, one-seventh Earth's gravity, so similar to our moon, but then it has a thick atmosphere. So if you were standing on the surface of Titan, you, and you had wings and you flap them, you could fly. And so it turns out that being able to fly doing these like multi-kilometer hops,

the dragonfly is going to do is actually a lot more efficient than it would be to just sort of drive like we traditionally do on Mars. And I'm involved in helping to figure out what the composition of Titan may be, whether or not there's a possibility of prebiotic chemistry, or whether indeed we find evidence of biosignatures today. All of that we could do with this mission. And it's such an exciting thing to be a part of. And I know that some scientists think there is no possibility of life on Titan because it is too cold. What do you say to that? The only way to test if that hypothesis is true or not is to go there and look, right? Certainly life, as we know it, could not exist on the surface. It is much too cold. And so any cell that needs liquid water, which as far as we know, all Earth life does,

could not survive on the surface. That being said, there could be pockets of liquid water from meteoric impacts and things like that. We've also got those hydrocarbon lakes, right? A different liquid that could allow for different chemistries to happen. And like you said, we don't really know unless we go there. Yeah. And every time we have sent emissions somewhere else, it is completely revolutionized our understanding of that world. Absolutely. And what are you working on for the Clipper mission, which is going to Jupiter's moon Europa? This mission is super cool. So we're trying to understand, you know, the gooey insides and the chunky bits that are inside Europa and what that might mean for habitability and for how Europa came to be and stuff like that.

And for the two instruments I'm involved in, one of them is called MIS, which stands for mapping imaging spectrometer for Europa. And it's basically just a fancy camera. and that gives us access to what you can think of as molecular fingerprints that tell us what the surface is made of. So we can tell the difference between different kinds of ice, different salts, or if there are organic molecules there, we'll be able to see what they are and where they are on the surface, which is really cool.

So that's mice. And the other instrument I'm involved in is called Suda. This is the surface dust analyzer instrument. And so this instrument is a great way to study the, things that are being sputtered off the surface. There are all these micrometeoid impacts that are happening all the time and shooting bits of Europa up into space. And then if Europa has a plume, when we fly through that plume with Europa Clipper,

we'd be able to tell you what the composition of the ice grains or the dust grains are made of. These missions sounds so cool. And as we close, Dr. Cable, do you have any advice for aspiring young scientists who are interested in the Jet Propulsion Lab at NASA? How can they aim their... spaceship in that direction. A lot of scientists, engineers, and the others who work here at JPL, had very circuitous past. But one common element I found is that they all pursued things they were passionate about

and just followed that wherever it took them. I have one colleague who worked in the pharmaceutical industry for a while and then looked up one night and was looking at Saturn and was wondering about Titan and decided that he wanted to change careers. And so he came and now we work on Titan stuff together. there are science writers that help us communicate. We even have artists, resident artists. So follow your passion, what you really love to do. And if there's some sort of space flavor to it, you could find yourself here working at JPL one day.

And I would love to meet you if you do. Dr. Cable, thank you so much for coming on the show. It was really great to talk to you. Oh, Emily, this was such a huge pleasure. And thank you so much for the invitation. And yeah, I mean, keep looking out, keep asking questions, and we'll do our best to give you answers. This episode was produced by Burley McCoy and Margaret Serino. It was edited by Giselle Grayson, who is also our senior supervising editor,

and fact-checked by Margaret Serino. The audio engineer was Josh Newell. Neil Carruth is our senior director of on-demand news programming, and Anya Grunman is our senior vice president of programming. I'm Emily Kwong, and you're listening to Shortwave, the Daily Science podcast from NPR.