Deep Dive
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$45 upfront payment equivalent to $15 per month. New customers on first three-month plan only. Taxes and fees extra. Speeds lower above 40 gigabytes. See details. I'm Noam Hassenfeld, and this is Unexplainable, a show all about unanswered scientific questions. And I'm here with reporter Bird Pinkerton. That's me. And Bird, you told me you had a question for me? Yeah. What are your thoughts on Jules Verne? Um, French guy.
Adventure books.
20,000 Leagues Under the Sea. Exactly. So when I was a kid, I loved Jules Verne stories because he would ask these big, wild questions like, what's going on with the moon? Can you go around the Earth super, super fast? Sure, sure. Like, can you journey to the center of the Earth? Exactly. And in the last hundred years or so, we have answered some of those questions. Like, we have, in fact, gone to the moon
We went around the world in 80 days, sure. Or perhaps fewer than 80 days. Who knows? Perhaps fewer.
But there's one question that Jules Verne asked that's still not fully answered. We've never been physically deep inside the Earth, so we still have a lot of questions about what's going on under our feet. Seriously? Yes. And that is the story that I am going to tell you today. It is this decades-long quest to get to not even the center of the Earth, but like...
slightly closer to the center of the Earth than we have ever been before. And in a roundabout way, it wound up changing how we understood the Earth itself. It's almost like a real-life Jules Verne novel. Let's do it. Okay, can you read this for me? Okay. Chapter one, a mystery to be solved at any price.
So, Noam, when I heard about this whole quest, I called up this wonderful geologist. Her name is Suzanne O'Connell. And I asked her to tell me about it. To understand this story, we have to know something about the deeper parts of the Earth. They're invisible.
And so we need seismologists who look at seismic waves traveling through the deeper Earth. You can think of this work from seismologists as how scientists build a map of what's under our feet. So when earthquakes happen, energy is released because of the rupture of the rocks and the energy travels through the Earth. And then seismologists measure this energy as waves.
And specifically, they measure how fast these waves travel through the planet. Because the really key thing here is that energy waves move through different materials at different speeds. So using this difference in travel time, seismologists started to figure out the structure of the Earth. Waves travel faster through things that are denser. So if something's not dense at all, like, say, sand, the waves will kind of slog through it.
And then if they traveled through something that was full of very dense minerals like olivine, which is a beautiful green mineral, it would travel even faster. Okay, so basically they're measuring how fast these earthquake waves travel and that lets them figure out exactly what the materials of the earth are?
It lets them figure out approximately what the materials of the Earth are. It's kind of like an X-ray. It gives you some information, but it's not every single thing going on inside your body. Okay, so it's more like a rough sketch. Yes. So that is the map. And this quest I'm going to tell you about, the seeds of it are planted in the early 1900s when scientists are first sketching this map. Okay.
As they're measuring these earthquake waves, they start to notice something weird. Okay. They're seeing that everywhere on the planet, under the ocean, under the land, wherever, there's this sudden change, this break in how fast the waves are moving. So you could imagine sound waves like going down, you know, maybe veering a bit and then...
All of a sudden they go a whole lot faster. And if the waves start getting a whole lot faster, I assume that means there's like a point inside the Earth where stuff suddenly gets really dense? Exactly.
Is that odd? It is odd. It's super odd. And they named it after this person who helped to find it. The Mohorovicich discontinuity, or the Moho for short. Okay, so what is this break, this Moho break? Well, they didn't know. That was the whole problem.
So this is this puzzle for decades. And like by the 50s, we'd figured out the Earth has a crust, which is kind of like the skin of the apple. It has a mantle, which is like the flesh of the apple. And then it has this core at the center. Mm-hmm.
But they didn't really know how these layers worked or related to each other necessarily. And they thought, hmm, maybe looking at this moho break, it might reveal the inner workings of the earth. Like, they were wondering, why is it such a sudden break? Why isn't it gradual? What could it be? What is this layer of dense material? Is it a layer of gold? You know, gold is very dense. Maybe it's treasure. Maybe it is treasure.
So there's a scientific conference in 1957. All these oceanographers and geologists are gathered there. And they're essentially there to figure out what little piece of science should they work on next. And they're reviewing proposals. The proposals are like fine. They're not earth shattering. No pun intended. Pun intended. Lobbing around. Pun intended. And so one of the people said, if we had all the money in the world,
what would we like to do? And so they started saying, let's drill to the moho. So like to drill to the layer where the earth gets really dense suddenly? Yes. And it's kind of, it's like the beginning of a Jules Verne novel to me. It's like, what the heck is this? We must discover. Perhaps a treasure. But this isn't like journey to the center of the earth. This is like journey to the edge of the center of the earth. It actually winds up being more like a different Jules Verne classic.
So you realize that on land, the crust rock is like 22 miles thick, so they'd have to drill through 22 miles. Versus in the ocean, the crust is only four miles thick.
So we're dealing with like a 20,000 leagues under the sea situation? Yes. They decide that they want to drill in the ocean as opposed to on land. So they go, they make their case to the National Science Foundation. And remember, this is like 1957, the year Sputnik launched. So a lot of their case is like,
You know, the Russians said they might want to go to the Moho. Like, perhaps we should go to the Moho first? So, okay, so this is like an ocean space race? Yeah, that's how they sell it. And they get funding for it, so they head off to prepare. Uh, next chapter, please? Oh, um, chapter two. Serious Preparations for Vertical Descent.
A scientific project is underway, a project called Project Moho, which hopes one day to drill a hole through the crust of the Earth and to find out what's down there. First thing they had to do was figure out if they could do something called dynamic positioning, because you can't just throw out anchors. The drilling ship will have to be held in position above the hole in water over two miles deep.
through long periods of time, night and day, in fair weather and foul. And once they'd figured out how to anchor a boat to nothing, they then had to figure out how to lower what was essentially like a very long metal straw, thousands of feet. The miles of drill pipe must be able to resist the wrenching forces of the ocean currents.
And then design a whole new kind of drill that would punch out like solid tubes of mud and eventually rock that they could analyze. It was like jumping off the deep end of the diving board and not knowing how to swim. It was that big a leap.
And because this is such a big leap, they decided to do like the very smallest version of it first. So they were still going to go to a really deep part of the ocean, but then they were going to drill like a hundred or so meters down as a test run. And to do that, they retrofit this old oil ship called the Cus One. Continental Union Shell and Superior. And in 1961, they are ready for... Noam? Yep. Chapter three.
Wonders of the Deep. Friday, March 24th. John Steinbeck is on the Cuss One when it takes off because he's covering this whole story for Life magazine. I climbed up the tower to the catwalk and it waved me like a fan on a hot night in New Orleans. I got our pal Will to do a bit of a dramatic reading for us. Got to thinking, the first importance of Project Moho is that it is being done at all.
We spend treasures daily on fantastical skyrockets aimed feebly towards space. And meanwhile, we know practically nothing of far the greater part of our home planet covered by the sea. And this new world is here, not a million miles away. They sail for several days and then Sunday, March 26th, they reach Mexico. Guadalupe Island in sight at dawn. We should be on our drilling station tonight.
On deck, the task of assembling 12,000 feet of pipe into a drilling string begins. The deck is heaving and pitching. As the steel sections of pipe rise and are screwed together and lowered, the men step like cats. And down goes the pipe, one 60-foot stand at a time. It is too exciting to go to bed. Tensely, the drillers watch the dial for a sign that part of the weight of the pipe is resting on the bottom.
The drillers are instructing me in watching the dials, indicating weight and pressure of mud in the pipe. That's it. That small flick of the needle. The drill touched bottom at 1215 and bit into the ocean sediment. Now we are drilling into the seafloor. From now on, everything is new. From now on, there is a constant vigil. Everything unknown. Day and night, we watch the dials.
Did we get a sample? Delight on the cuss. We brought up a great core of basalt, stark blue and very hard, with extrusions of crystals, beautiful under a magnifying glass. They end up bringing up like a bunch of these, they're sort of cylinders of mud and rock, which they call cores because, have you ever like cored an apple where you sort of punch out a tube? It's kind of like that, but for the seafloor.
The scientists are guarding this core like tigers. Everyone wants a fragment as a memento. I asked for a piece and got a scowling refusal, and so I stole a piece. And then that damn chief scientist gave me a piece, secretly making me feel terrible.
I had to sneak in and replace the piece I'd stolen. They start analyzing the cores on the ship, they plan to study them more on land, and they're feeling really good about all the research that's to come. Through the Moho, we'll add new direct evidence to our knowledge of the Earth. And somewhere down there, perhaps, great unexpected discoveries are waiting to be made by the scientists, engineers, and technicians of Project Moho. And I hope I may be invited back.
when the new ship sails towards new wonders in about two years. All right, that was chapter three. I will give you chapter four after the break. Can't wait. Well, you have to. Support for Unexplainable comes from Greenlight. People with kids tell me time moves a lot faster. Before you know it, your kid is all grown up. They've got their own credit card and they have no idea how to use it. But you can help. If you want your kids to get some financial literacy early on,
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Okay, Unexplainable, we're back. Bird, you've been telling this story about scientists trying to get to the Moho Break, which is this place inside the Earth where the materials suddenly get really dense and we don't really know why. And I guess the first step of the mission was a success. They drilled really deep under the ocean and they actually got some rocks from the bottom. Yes.
So to be clear, they were nowhere near the Moho. Like they went 100 meters and they needed to drill four or so miles. But people were really jazzed about this as a kind of a proof of concept. So did they build a new boat? Did they get Steinbeck back? No, they did not build a new boat. Okay. So how did they get to the Moho? They did not.
Wait, they never? Super bummer twist. Okay. So it has been six decades since Project Moho, and we still do not have a fresh sample of this moho break. Suzanne told me that the kind of excitement and thrill of the first experiment didn't really last very long. This becomes like a...
I think, a really shameful part of the history and how it happened. After that first trip, the next step was for scientists to build their own ship. But they ran out of funding, and then there was all this infighting, and eventually the project ended. So the whole thing was like a bust? Project Moho was a bust, but it laid the foundation for exploring the ocean, which hadn't been done before, and we still don't know that much about it. And
Every day, almost, we learn something so exciting and so important about our planet. Which leads us to... Chapter 5, Into the Unknown. ♪
The scientists did not reach the Moho, but they did develop this totally new way to bring up samples from the bottom of the ocean. Other scientists are looking at this. They think it's kind of cool. So they decide to go and drill shallow holes essentially all over the place. And so for many decades now, they have been bringing up these cores, these cylinders of mud and rock to
and using them to study parts of the deep ocean that, until this point, no one had ever seen before. It changed the way we saw the Earth. For example, it created a whole new field, which is actually Suzanne's field, paleo-oceanography.
paleo-oceanography? Oh, yeah. What is paleo-oceanography? Well, paleo, past oceanography, oceans, past oceans. Suzanne's job, it's the coolest job in the universe. She gets on these research vessels. She says it's kind of like going to summer camp. All you have to do is look at cores. You hang out with other people looking at cores. And you're like,
which is as close to heaven, I think, as you can get. They play these like very dorky chalk pranks on each other. Chalk pranks? You take a little bit of chalk.
And you'd put it in the sample. And they show that sample to their colleagues like, I think we found a nanofossil, a calcareous nanofossil layer. But what she's really doing all day when she's done with her chalk pranks is she's looking at cores and samples from the seafloor. And she essentially reads these cores like a book.
And this book tells her all about what the planet used to look like millions of years ago. How does she do that? So she cuts these cylinders of ocean mud open, and they're full of a kaleidoscope of little fossils. So they've got, like, dead.
dead algae called coccolithophores. They're like little, tiny, intricate plates. They've got shelled organisms called foraminifera. And they look like popcorn. And they've got plant-like organisms called diatoms. Both radulaire and diatoms remind me a lot of the styrofoam balls you often have at Christmas. And she can use all these little fossils and bits and pieces as like clues to understand the climate in the past.
So, for example, at one point she was looking through a sediment core near Antarctica and she found these little bits of pollen. And she was able to use that to say, hey, I think there used to be beach trees on Antarctica. Beach trees? Yeah. Which is really weird. It's weird to think about trees on Antarctica. But what I think is cool is that it's not just like, oh, there were trees at Antarctica once.
at one point. She can look and sort of see, all right, what's in the next layer or what's in the layer before that? How did the climate shift in Antarctica across time? And how quickly did it change? Like how quickly did it move from cold to hot to cold again? We, people like me, grew up in sort of the gradual world. Everything happens slowly and eventually things change. No, we know from ocean drilling that things can happen really fast.
Paleo oceanographers, they can look at the end of the Cretaceous, right? This is 66 million years ago, long before humans. But there was a big climate change related extinction event. So they can see, all right, how fast did the climate change then? And they're using that information to inform the models that we're building now as we try to predict how fast humans are changing the climate. Quick question.
Why is she not just doing this on land? Like, why is she doing this at the bottom of the ocean? So on land, you have a bunch of erosion and people wandering around and earthquakes screwing up the layers. That's why the ocean is better than land, because on land, those layers have been all crumpled up, whereas in the ocean, nobody's crunched them up yet. Okay. Yeah.
Can I tell you another cool thing that all this drilling research has brought up? No. Great. End of podcast. Okay. Tell me. So the other thing that I got really jazzed about was that it inspired research on the limits of life itself. It started with literally just scientists going out on cruises and just collecting samples and counting cells, which sounds really boring because it is.
Talked to this great guy. His name is Jason Sylvan. He's a microbiologist at Texas A&M. And he told me that they kept drilling like deeper and deeper, first into the mud, eventually into sort of the layers of rock at the bottom of the ocean. And going deeper and deeper and deeper into that seafloor, there's stuff that's alive.
What is life like all the way down there? It is very weird. Okay. So there are these really extreme conditions down there. There's like very few resources. In some places, there's no oxygen. It can be super hot sometimes. And it helps us ask these questions like, how hot can it get before things just stop living? Or like, what do you do when you have almost no food and no oxygen at all?
Okay, what do you do? You do a bunch of different things. Some microbes team up, so you have balls of microbes that form and kind of share chemicals that they need to survive with each other. And then some microbes freeze up, so microbiologists have found organisms that have been in stasis for thousands of years. Which...
doesn't really vibe with everything else we know about life. Like it's a question they have to ask. Are you actually alive if you've just been asleep forever? Yeah, I mean, thinking about all these places in the deep ocean with these extreme temperatures and no food and no oxygen, I mean, it's kind of like deep space at the bottom of the ocean. You are actually not the only person to think that, Noam.
Some of these scientists are teaming up with NASA, actually, because they're essentially, they're looking for life on other planets or like on moons of other planets. And there are conditions in deserts, there are conditions at the bottom of the seafloor that might resemble the conditions on those planets or those moons. So NASA is interested in essentially saying, okay, well, see what you can learn about what life looks like in that type of environment here, since we can actually sample that. So
So this is kind of a way to get a head start on looking for life all across the solar system. Wow, okay. So a lot is coming out of a drilling attempt that didn't really get that far. Yeah, to quote Suzanne... We have learned so much about our own planet that we just didn't know. And there's really no way we could have done it unless we had cores to look at. And on that note, one last thing.
Is this chapter six the end? Okay. Even after 60 years, scientists have not given up on getting to the moho. There is a proposal in now through the Scientific Ocean Drilling Program to drill to the mantle and get a piece of moho. So fingers crossed, we might just get it. Amazing.
It is amazing. I love that there are still people trying to figure out how we might bring up just like a couple of pieces of this break. And the geologist I spoke to think it could really unlock cool secrets about the Earth.
What kind of secrets are we talking about? So they said that it could help us understand like the mechanics of plate tectonics, how plates are moving across the earth, and that that will help us sort of understand the earth as a system more in depth. I mean, I guess like we still don't really know how to predict earthquakes and stuff. I mean, there's a lot we don't know about earthquakes.
how the Earth moves under our feet, right? Sure. And there are potentially other unknowns that we haven't even thought of at all, like things that if we pulled up a piece of the mantle, we would realize we wanted to ask questions about. If you think about it, when we looked drilling into the surface sediments, we had no idea what the surface sediments of the ocean was like. And it defined a whole new field of geoscience, paleo-oceanography. And there could be a whole new field of mantle rheology
that could be discovered with more pieces of mantle material. And this unknown place is not a bad place to be. Like, when I think about this story as a Jules Verne book, Jules Verne books have these really clear goals, and then the characters get totally distracted along the way by other exciting science.
And I think the quest for the Moho is similar in that we have essentially taken a detour into very exciting ocean research. It is exciting. Every time I think about it, it's exciting. So, like, maybe we will get to the Moho eventually. Who knows? But in the meantime, we're just halfway through this really cool book and we get to keep reading. So it's like chapter six, the end for now? Yeah, or like...
Chapter six. I can't wait for chapter seven. This episode was reported and produced by Bird Pinkerton. Noam Hassenfeld helped produce and also handled the music. Editing from Jillian Weinberger and Brian Resnick.
Liliana Michelena did the fact-checking, and Hannes Brown did the mixing and sound design. I'm Meredith Hodnot, the senior producer of Unexplainable, and Liz Kelly Nelson is the editorial director of Vox Podcasts. Special thanks also to Donna Blackman and Henry Dick for their time and expertise, and thanks to Will Reed for his swell reeds.
If you want to read more about the Scientific Ocean Drilling Program's plans for MOHO, or about the 50-year plan for the future of ocean drilling, sign up for our newsletter. There's a link down in the show notes. And while you're down there, check out that link for our website too, box.com slash unexplainable, where we've got an article with more information about the initial project MOHO and more about the archival documentaries that we drew from.
Are you stuck on any other unsolved geological mysteries? Do you know of any other expeditions that went so wrong that it actually went right? Send us your thoughts. Email unexplainable at vox.com. We read every email. Unexplainable is part of the Vox Media Podcast Network, and we'll be right back in your feed next Wednesday. Thanks for listening.