What’s hiding under the Antarctic ice?

Some of the largest lakes in the world have been buried under miles of ice for millions of years. Is there life hiding down there? And if so, could life be found in even more extreme places … beyond our planet? Guest: John Priscu, microbiologist at Montana State University For show transcripts, go to vox.com/unxtranscripts For more, go to vox.com/unexplainable And please email us! [email protected] We read every email. Support Unexplainable by becoming a Vox Member today: vox.com/members Learn more about your ad choices. Visit podcastchoices.com/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Speaker 00

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• 1:35Speaker 02

  It all started looking out that window.

• 1:38Noam Hassenfeld?

  On his first trip to Antarctica, John Priskill couldn't stop staring out that little oval porthole at the cargo plane.

• 1:45Speaker 02

  This is a whole continent, right? It's covered with ice. It's just white.

• 1:50Noam Hassenfeld?

  Most people who've seen all that endless white, they figured it was basically empty.

• 1:56Speaker 02

  They painted this picture of this awful place for life. I mean, we all know about the stuff around the coast, right? Penguins, seals, georgurds. But everybody thought that the rest of the continent was just a big benign block of ice.

• 2:13Noam Hassenfeld?

  Which makes sense. Like, it's Antarctica.

• 2:16Speaker 02

  It's really harsh at the surface. I mean, the average temperature of Antarctica is about, you know, minus 60 centigrade. And it's really dry, dark, more than half the year. That's a tough place.

• 2:28Noam Hassenfeld?

  But John's used to tough environments. He's a microbiologist. He studies life that can survive in some of the most extreme places. And when he looked out that window, it didn't seem impossible.

• 2:44Speaker 02

  It can't have this much real estate on our planet that's lifeless.

• 2:49Noam Hassenfeld?

  John knew that if there actually was a ton of life in the middle of Antarctica, it wouldn't be on the surface. It would probably be somewhere way deeper, somewhere no one's ever been before.

• 3:00Speaker 02

  We know more about the surface of Mars than we know about the subsurface of the ice in Antarctica.

• 3:08Noam Hassenfeld?

  I'm Noam Hassenfeld, and this week on Unexplainable, is there life miles beneath the Antarctic ice? And if there is, where else might life be hiding?

• 3:34Noam Hassenfeld?

  So, John, intuitively, I would think if you went deep under the ground of an already inhospitable place, it would get more inhospitable. I wonder, how is it possible that life can survive in a place that is that cold and no sunlight?

• 3:53Speaker 02

  Let's go right to the bottom. Some of the largest lakes on our planet are under the Antarctic ice sheet.

• 3:59Noam Hassenfeld?

  There's lakes under the ice sheet? Like, fresh, like, liquid water?

• 4:03Speaker 02

  Liquid water lakes. So, uh, it's over 600 have been identified. One of the lakes, I think it's the crown jewel of lakes, is Lake Bostock. It's over in East Antarctica, and that lake is under two miles of ice. The lake is 3,000 feet deep, and it's the size of Lake Ontario. So, this lake has been ice-covered for...

• 4:26Speaker 02

  More than 15 million years, so it hasn't seen a ray of light or a whisper wind for 15 million years.

• 4:33Noam Hassenfeld?

  And how is it, how is it liquid down there?

• 4:35Speaker 02

  Yeah, now that is, that's the question I was waiting for. Yeah. How do you get liquid water when the average temperature at the top is like minus 60 centigrade?

• 4:44Noam Hassenfeld?

  Yeah.

• 4:44Speaker 02

  First of all, you get about a couple of miles of ice. Ice is a really good insulator, right? So if you look at the temperature profile in, in the ice sheet, it starts out really cold. And then it warms up, warms up till you get to about zero centigrade or the melting temperature of ice. Secondly, we have a lot of pressure. So when you put pressure on the system, the freezing point changes a little. So water doesn't freeze it at zero centigrade. It freezes like minus one.

• 5:13Noam Hassenfeld?

  Okay.

• 5:13Speaker 02

  And then the third and the most important ingredient is just heat flux from the earth. We know there's always heat coming up out of the earth everywhere, every, because we have this molten core on a planet conduction. So we have a little bit of heat, right? We have a great insulator from the cold. And we have a little bit of a freezing point depression. It's, it's really a precise system.

• 5:39Noam Hassenfeld?

  So how'd you get all the way down there and actually study these lakes?

• 5:43Speaker 02

  Our first expedition was into subglacial, uh, Lake Willens, under the Willens Ice Stream. Also, the ice was only like 3,000 feet thick. Okay? You know, if we want to go under the Antarctic ice sheet, we get there by melting. So we had to develop a clean drill. It's like a big steam cleaner, you know, big hot water hose. We had to develop, uh, sleds that we could pull and, and buy tractors. We had to buy like seven tractors. And get them all the way to the United States to Antarctica. And then drive them for two to three weeks to get out to our field sites, pulling all the loads out. And then make a runway to bring aircraft in. So it was, it was a big effort.

• 6:27Speaker 02

  So we get out there right at the end of December 2012 and started drilling. The drilling took about a week to get a hole that's about three feet diameter to get our tools in. And then the drillers popped through and we got into liquid and everyone was just like, this is awesome. There was elation. I mean, you could hear roars from all the tents and everybody in our field camp. There were 52 of us. But then, all of a sudden, the work started, right? The drillers pulled their drill out, turned it over to us, and we started sampling. The first thing we did was put down cameras to make sure, you know, you gotta

• 7:10Speaker 02

  see something. And we could see the ice, we could see the sediment on the bottom of the ice sheet. And then we got into the water column and saw the bottom of the lake. So the water was a little off color, that was a little turbid, the bottom of the ice was very dirty. I remember people said, wow, this is not at all what we expected. I mean, we didn't know what to expect. So let's put it in a big framework. It's like, this is all exploration. And then we sent down a sampling bottle, I guess you can call it a system. So we brought water up. First thing we did was put it under a microscope, stained it with the water sample with a DNA stain, and we saw cells.

• 7:54Noam Hassenfeld?

  Wow. I mean, you're seeing something that, I guess, tell me if I'm wrong, but you're seeing something that no one in human history has ever seen before.

• 8:01Speaker 02

  That's true. Yeah. It was, being a polar scientist, it was like the highlight of my career, right? But what surprised me was how much and how diverse it was. It's a thriving ecosystem that lives without sun. So it's much like a deep sea vent in a way, except it's a cold system.

• 8:24Noam Hassenfeld?

  What did, what did the scientific community think? I mean, did people question the findings? Did they think it was impossible that life could live down there?

• 8:33Speaker 02

  Yeah. For any new discovery, you got to have extraordinary data. Think of it as going to Mars and reporting life. You better have your act together.

• 8:41Noam Hassenfeld?

  Yeah.

• 8:42Speaker 02

  We wore Tyvek suits. We sampled all of our drill water every day.

• 8:47Noam Hassenfeld?

  Is this because you're, because you're worried about contamination or something?

• 8:49Speaker 02

  Yeah, exactly.

• 8:50Noam Hassenfeld?

  Like bringing down life from the surface?

• 8:52Speaker 02

  That's right. Or life from us. So samples went into a clean lab. Everyone's Tyvek'd up, masked up, and we had to convince the world that it wasn't contamination. But I think we did.

• 9:05Noam Hassenfeld?

  Tell me about the actual life you found down there. What kinds of microbes you found? What they, what they look like?

• 9:12Speaker 02

  Yeah. So it probably took a month after we brought samples back to really do the hardcore, deep sequencing of DNA to really find out who they are and how they made a living. There's no solar radiation down there. There's no energy coming in from the sun, but there is energy in the rocks.

• 9:34Noam Hassenfeld?

  Okay.

• 9:35Speaker 02

  Now, plants on the surface of the earth, they use CO2, but they get their energy from the sun. The organisms in the dark use CO2, but they get their energy from minerals.

• 9:45Noam Hassenfeld?

  Okay.

• 9:45Speaker 02

  Okay.

• 9:46Noam Hassenfeld?

  So they're using, they're just using the chemicals that are already down there instead of sunlight?

• 9:50Speaker 02

  Yep, exactly.

• 9:51Noam Hassenfeld?

  Got it.

• 9:52Speaker 02

  Uh huh. Like ammonium, methane, iron, sulfur. So they can break those chemical bonds and, and take energy from them. So that, what they're doing is then they're mobilizing nutrients. And as these lakes flush to the ocean, they're actually, it's actually fertilizing the continental shelf in Antarctica.

• 10:15Noam Hassenfeld?

  Are you saying then that there's, there's like sub-ice rivers that take this lake water to the ocean?

• 10:21Speaker 02

  Oh, yeah. In the area where we sampled in West Antarctica, we're under ice streams, where these lakes fill and drain about every decade, and that water flows right out to the ocean.

• 10:35Speaker 02

  I teach a lot of biology courses and geology courses and Earth's biosphere, the definition of the biosphere, never included Antarctica. It took 20 years of my life, as well as others, to convince the people to fund us to do this. And now we showed it. Instead of being a big benign block of ice, we could say that it is a thriving biological community. And it like, it's part of the Earth's system. It transforms nutrients to the ocean. It's hosting this whole biodiversity that we don't know about. So now we're finding a whole group of viruses that are unique. We have bacteria that are quite unique from all the surrounding oceans.

• 11:20Speaker 02

  So we're just starting to unravel it.

• 11:23Noam Hassenfeld?

  But you're saying there's essentially this enormous hidden ecosystem that is shaping the rest of the planet because it is filtering into the rest of the planet and we're just kind of starting to understand it.

• 11:38Speaker 02

  And that's the key thing. It's, it's part of the Earth's system. It's this deep biosphere under the ice sheet. And as we're losing our ice, we may lose it too. So, you know, it's, it's got a lot of ramifications. We're just starting to study this, really? There's, you know, there's only been two samples. There's over 600 lakes and then there's these big giant lakes like Lake Vostok. We haven't sampled those. We've been sampling these low hanging fruit lakes. It's just the beginning, but it's really hard to get in and do the work.

• 12:13Noam Hassenfeld?

  John's work has transformed the way we see Antarctica. It's gone from a seemingly lifeless place to one that we know is teeming with life. But understanding what's down there in one of the most extreme environments on Earth, it might help us understand something way bigger. What life could look like beyond Earth.

• 12:35Speaker 02

  So now that we understand the life under the ice sheet, it has opened huge doors for me to be part of the NASA exploration to ocean worlds.

• 12:45Noam Hassenfeld?

  That's in a minute.

• 12:49Speaker 00

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• 16:02Speaker 05

  Allow me to break the ice. My name is Unexplainable.

• 16:08Noam Hassenfeld?

  Around the same time, John started exploring lakes deep under the Antarctic ice, NASA made this groundbreaking discovery. There might be liquid water hiding deep under ice on other planets and moons in our solar system, like entire oceans' worth of sub-ice liquid water, which means there might, might be life there. One of the most promising spots is Jupiter's moon Europa. And a few months ago, NASA launched the Europa Clipper probe to figure out just how habitable it might be.

• 16:43Speaker 06

  Three, two, one, ignition. And liftoff. Liftoff. Falcon 7 with Europa Clipper.

• 16:51Speaker 07

  Took off Monday from the Kennedy Space Center in Florida.

• 16:54Noam Hassenfeld?

  Arriving in 2030, Clipper will make 49 orbital flybys of Europa to search for the basic ingredients of life. But NASA needed someone who really knows their way around subsurface ice, so they teamed up with John. And over the last few years, they've been working on a way to figure out if there might be extraterrestrial life right here in our own solar system.

• 17:20Noam Hassenfeld?

  So tell me about Europa. What do scientists think it's like there?

• 17:25Speaker 02

  Firstly, it's got an ice shell, a full ice shell. So that ice moves around just like our Antarctic ice sheets do. The ice is maybe 10,000 feet thick. And then it's got a liquid water ocean under it. You have an iron core at the bottom of that moon. That generates heat, right? And at the surface of Europa, there's a huge amount of radiation coming from Jupiter's magnetosphere. It'd be really hard to live there. But you've got this nice clement environment. Under the ice, nice thick insulating blanket, a heat source in the bottom, some pressure to lower that freezing point a little bit. And there's no sunlight under that much ice.

• 18:06Speaker 02

  So our subglacial work under the deep ice sheets is a perfect earthly analog to what we would see in the ocean worlds beyond Earth.

• 18:19Noam Hassenfeld?

  I'm curious, you know, what we've learned from the kind of subglacial Antarctic microbes you've studied that could help us find or maybe understand life on Europa?

• 18:30Speaker 02

  Well, first, we've defined a habitat. That's really important, that could support liquid water in a place you'd never think it would be. We've defined in Antarctica organisms that can survive in this habitat, that eat minerals for energy. They can transform nutrients. They can live in cold environments. So we've defined a habitat.

• 18:51Noam Hassenfeld?

  So what's the actual work you're doing with NASA? Like, what's the research?

• 18:55Speaker 02

  We're putting robots under ice in lakes that are frozen. So we call that Rover Brewey. It's a buoyant rover for under-ice exploration. So this was developed at JPL with NASA funding. It's positively buoyant. It has big wheels on it. It has lights. It can do 360s. And it crawls along on the bottom of the ice. And now what we're doing is putting instruments on a little tail. To collect data.

• 19:22Noam Hassenfeld?

  Mm hmm.

• 19:23Speaker 02

  Because I would hope the follow up mission to Europa after Clipper will be a lander.

• 19:29Noam Hassenfeld?

  Got it.

• 19:30Speaker 02

  So the Clipper is going to give you a lot of data on the surface so that we can then plan a lander. And then eventually a drill to get into the ocean.

• 19:40Noam Hassenfeld?

  Hmm.

• 19:41Speaker 02

  And then to put under ice rovers in and let them collect data. There's no way we're going to make it. A human is not going to walk around on the surface of Europa anytime in our lifetime.

• 19:52Noam Hassenfeld?

  But we're going to have to have some kind of rover that has like a 10,000 foot drill attached to it?

• 19:58Speaker 02

  There are many concepts. I've been to many think tanks on how to drill through it. You can't do it like we do in Antarctic with hot water. And they'll have to go down and the hole will seal behind them. It'll free shot. And when they break through, they're going to have to open up a little bay. Out comes a little rover, right? You know, and I mean, something's going to go around and swim around.

• 20:21Noam Hassenfeld?

  Mm hmm.

• 20:22Speaker 02

  Yeah, so that's what we were doing a concept of in the Arctic with with our rover called B R U I E.

• 20:29Noam Hassenfeld?

  That's Brui.

• 20:30Speaker 02

  Yeah, yeah.

• 20:31Noam Hassenfeld?

  Do you have any sense of of when something, if something like that could be possible in our lifetime?

• 20:38Speaker 02

  Yeah, I do. I think it will be in your lifetime, maybe not mine, but.

• 20:42Noam Hassenfeld?

  Do you think there's life down there?

• 20:45Speaker 02

  I do.

• 20:45Noam Hassenfeld?

  Do you think we're going to find something down there?

• 20:48Speaker 02

  I'd be in denial if I said no. Yeah, why not?

• 20:54Noam Hassenfeld?

  You really, you really think there's life down there?

• 20:55Speaker 02

  Yeah, so I don't think we're alone. And I don't mean higher life forms. You know, these ocean worlds beyond Earth have been around since the beginning of our solar system. So to get life to originate, you need time for all these molecules to come together and make complex molecules like DNA and RNA and proteins. You need liquid water. You need nutrients. We think the Europa Ocean has nutrients from this satellite imagery, the salts. I mean, yeah, I, why would it not? I mean, I'm taking off any metaphysical hats or anything. I'm just looking at pure chemistry and physics. You've you've got everything to support life out there.

• 21:36Noam Hassenfeld?

  And do you think life on Europa could potentially look like the life in the Antarctic Lakes?

• 21:42Speaker 02

  I do, because the environment that we defined in Antarctica looks like it's pretty similar to the environment in the European ocean. Yeah, it's got all the ingredients.

• 21:58Noam Hassenfeld?

  I don't know, just just the idea of Antarctica being an analog for a moon of Jupiter. You know.

• 22:06Speaker 02

  Pretty cool, huh?

• 22:07Noam Hassenfeld?

  It makes me feel like there are parts of Earth that are as unknown as Europa, that are as alien as Europa, that there's so many parts of this planet that that we still don't know. I mean, you're talking about a completely hidden ecosystem that is shaping our biosphere. I wonder if the connection between your research here at home and the search for alien life, does that make you think about Earth differently?

• 22:32Speaker 02

  For sure it does. When I'm out in the deep field and I'm walking in the same area where Robert Falcon Scott walked, I've been there walking, you know, and I just know that under my feet it's teeming with life, just huge amounts of life. Maybe I feel a little more at home by that. It's a little more habitable. I would not have thought that before. And if we found life beyond Earth, not little green man, not the purple blob, but but a whole microbial system that's with organisms similar to Earth or even different, I would hope that the human population would be humbled for at least 10 minutes by by the fact that we're not alone.

• 23:31Noam Hassenfeld?

  This episode was produced by Mandine Nguyen. It was edited by Meredith Hoddinott, who runs the show. Mixing and sound design from Chris Janayala. Music from me and fact checking from Anuk Dusso. Thomas Lu is working on a universal translator. Byrd Pinkerton is making her way back to the octopus hospital. And we're always grateful to Brian Resnick for co-founding the show. We've also got some news this week. This was Mandine Nguyen's last episode on the show. She's been with us almost since the very beginning. And we couldn't have made this show what it is without her curiosity, her incisiveness, and above all, her empathy. When I think of Mandy's contributions to our show, I always think back to the time she flew to Texas

• 24:14Noam Hassenfeld?

  to search for a lost species of salamander. She went swimming in an underground cave. And afterwards, she sat down and collected her thoughts.

• 24:24Speaker 01

  Pure darkness. All I can hear is our breath and the light splashing of water. I stop feeling cold. I don't notice my own short breath. I can't register anything. For a moment, I feel myself disappear, dissolving into the dark world of water and salamanders.

• 24:48Speaker 00

  Mandy is an adventurer at heart. And she cares so deeply about understanding the world around her. Everything from mushrooms to the Mariana Trench. But most of all, she cares about people and their stories.

• 25:02Noam Hassenfeld?

  Thanks for everything, Mandy.

• 25:11Noam Hassenfeld?

  If you want to tell us how much you love Mandy or if you have any other thoughts about the show, email us, we're at [email protected]. You can also support this show and all of Vox's journalism by joining our membership program today. You can go to vox.com/members to sign up. And if you signed up because of us, send us a note. We'd love to hear from you. Unexplainable is part of the Vox Media Podcast Network.

• 25:58Speaker 01

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