Louisa Preston says that hers may be the only field in which scientists don't know if the object of their study actually exists. The 33-year-old Preston is an astrobiologist working on the quest to find extraterrestrial life. But her work is more likely to involve examining soil under a microscope than sending signals to the outer reaches of the cosmos. In her recent book, Goldilocks and the Water Bears: The Search for Life in the Universe, Preston offers an introduction to the search for extraterrestrial life—a search that sheds surprising light on our own planet and biological history.
Preston's book takes its punny title from two important concepts in the search for ET life. The first is the "Goldilocks Zone," which refers to the set of conditions on a planet that would allow life to develop. But the criteria is far more rigorous than eliminating "too hot" and "too cold": To support life, a celestial body must offer potential inhabitants protection from radiation, have a nice insulating atmosphere, a decent amount of gravity, be a certain distance from the star it orbits; even plate tectonics help make a planet habitable by maintaining an environment that's warm and water-rich.
The second concept is the "water bears" of Preston's title, tardigrades, multicellular critters that look uncannily ursine. Tardigrades are one of the only creatures that could survive in space—they're hardy enough to survive a vacuum and extreme cold, can expel almost all of the water in their bodies and go into hibernation, only to reinflate themselves and come back to life when they happen back into a friendlier environment. Water bears belong to a class of organism called extremophiles, who live in corners of the planet that are hottest, coldest, most acidic, or most crushed by pressure, etc. Think the Mariana Trench, or Antarctica's subterranean liquid Lake Vostok, or Spain's salty and sulphurous Lake Tirez. Investigating these animals and how they survive in their almost-alien habitats gives insight into how life outside our planet could work.
One expects the takeaway from Preston's book to be—in classic cosmos-narrative style—a feeling of awe at the size, scope, and strangeness of the universe. And you do get this feeling, as she walks readers through a tour of the spots in our solar system (and beyond) where we might one day find life or evidence of past life. But more striking is the sense of how very special our own planet and moment in geologic time are. It's a compelling book to read at this moment, as man-made climate change is throwing planetary systems off balance. In her brief history of the Earth, and of the other rocks that hurtle around space with us, Preston shows just how very lucky we are to live on a planet that is—for now at least—just right.
Recently I sat down and talked about all that with her.
VICE: I'm wondering about the day-to-day life of an astrobiologist. Are you visiting extreme places on earth, looking at a telescope, working in a lab?
Louisa Preston: You know its probably exactly the same as most people—I come in and sit in my office and do research. I do go into the lab sometimes but I'm either looking at organisms down the microscope or crushing up rocks, which is extremely therapeutic. Or I'm using this thing called a spectrometer, which bounces infrared light off these organisms so that I can figure out what's inside them. You're working toward something that you might not ever get to the answer, you're just putting together little pieces of the puzzle for quite possibly the next generation of scientists to figure out. But then there is obviously the fieldwork, which is the best bit.
What are some of the more memorable of those extreme, alien-like environments that you've visited for your fieldwork?
My favorite is Iceland. It's incredible, it's almost cathartic. I worked around Eyjafjallajökull, the volcano that caused the ash cloud. We went up there nine or ten months after it erupted, because we wanted to see how much life could survive there, what were the first organisms to make it back. It was difficult to do—mainly because it was so hot. You could still see lava flowing underneath the ground. The soles of our boots started to melt as we were hiking. But it was still snowing. It was such a strange environment, but you could look at it and think: There's heat, there's water, there's all these volcanic minerals that organisms love—it's a perfect environment for some really tough organisms. And the minerality there in Iceland is the same as Mars. It looks very similar, and for us it's a great site to compare because it's quite remote.
"I'm not a betting person, but if I were, I would bet there was life on Mars and we will find evidence of it in my lifetime."
This is one of the only fields where you're not sure if the object of your study exists. So I want to ask you—do you believe that other life is out there?
I say, part spiritually: I do believe it. But also, looking at all the evidence, I can't get my head around how life could have only have arisen once. I just don't think that's the case. I don't necessarily think that there's really intelligent life out there, as in life that we're going to be able to communicate with. I don't think that we're clever enough to do that yet. But small microbial life, absolutely. I'm not a betting person, but if I were, I would bet there was life on Mars and we will find evidence of it in my lifetime. I'm sure we will.
Is that because the universe is so big that it's a numbers game, there are so many places and settings out there that this process has to have happened more than once? Do you feel like there's something inevitable about the process that you describe in the book, life rising out of the hydrocarbon soup?
I'm not sure if it's inevitable. I think there's been a lot of strategic moves made by life, but also some lucky chances. But I find it hard to ignore the fact that we're finding water everywhere. Carbon's the third most abundant element in the universe—it's found in all the rocks and all the dust that we find. And energy is everywhere because the sun provides it or the planets or moons provide it—and that's all that life really needs. It may not have got as far as us, it might have happened and died out. We think that on Earth, life arose and was killed off multiple times before it really caught on and developed into multicellular life and beyond. Like Carl Sagan said, it would be an absolute waste of space, it really would, to have all the ingredients floating around and nothing being made of them.
"Anything that can get sent into space, and be exposed to a vacuum, and to subzero temperatures and to radiation, and just basically go to sleep and them come alive once it gets oxygen and water again, and then can carry on and have babies—that's incredible."
What makes you think that the form is more likely to be smaller, microbial, rather than a higher, intelligent life form?
It's because it's easier to build. Because they are so simple, they require a very basic set of ingredients. We don't know how the chemistry suddenly became a biological organism—we don't know how that happened—so obviously that is a tough step. But they're just simple, and they're stronger than us, they're so much tougher. If there was life on Mars before, and it started to get cold or it started to be bathed in radiation, or started to lose its water, those organisms could adapt and evolve. They could have gone underground; they could have tried to find a way to survive. Whereas we would have been killed off instantly. We're so weak. We have brains, but we can't save ourselves, and we can't adapt. So I just think that they're the hardiest, which is why we call them the extremophiles. Like the water bears.
You have this—
I was going to say affection, for water bears. What's so special about them?
They can survive anything. Anything that can get sent into space, and be exposed to a vacuum, and to subzero temperatures and to radiation, and just basically go to sleep and them come alive once it gets oxygen and water again, and then can carry on and have babies—that's incredible. And the fact that we can't figure out how they do it. The thing is, the more we study the water bear, the more it can help us with our own future survival. I mean for life on Earth—forget space—the way the tardigrade can survive things is what could help us make our planet better.
Watch the Motherboard documentary about water bears:
What we think they might do is, there might be certain genes that they can switch on and off depending on the environment. What is it that tells them to expel 97 percent of their water and then later get it back again—how does that work? If there's a gene in there that can survive really cold temperatures, could that be put into a crop? Not that genetically modifying things is definitely the best way to go, but for drought areas or for trying to get more crops into cold areas, is there something that tardigrades or other extremophiles do that could be vital? Also in terms of medicine, if we understood how extremophiles adapt and survive, that knowledge could help us immensely. People always say this thing about Mars being a lifeboat—that we could end up on Mars. But the thing is we need to save our planet first, to even have the right to have another world. So we need to be able to understand how to protect it better.
As I was reading I was thinking about all of these other planets, and the history of life on Earth. You have this understanding of planetary history that most people don't have, and I wonder if that colors your thinking about issues like climate change.
I know a lot of climate scientists who are very much like, "This is the way the Earth works. You adapt or die, that's the way it works." I see it as just worrying. Because you know that it has happened before. I study extinction events, and I see what's happened in the past. Those events have wiped out organisms that were tougher than we are—but then we do have brains and we might be able to fix it. We look at Mars and think, That could happen. And we look at Venus and think, That could happen, if we're not careful. And we wouldn't survive it.
"If I had to be stranded any place in the solar system I would choose to be stranded on Titan, because I could fly."
In the book, you tell us about the conditions on various planets and moons in our own solar system that make them more or less hospitable to life, and then you do the same thing with some of the exoplanets. Is there some particular spot out there that you are rooting for as the most likely source of extraterrestrial life?
With exoplanets, I try not to get my hopes up, because it's going to take too long to figure it out, to get a definitive answer.
I would love Enceladus [a moon of Saturn, covered with ice and cryovolacanoes] to prove itself. It's got all the ingredients. It's already showing us that it's got active, organic molecules being spewed out into space. The same with Europa [the smooth-surfaced, icy moon of Jupiter] as well, that would be really good, although drilling through the ice might be quite difficult. But I have to say Titan [a moon Saturn with a dense atmosphere and evidence of lakes of liquid hydrocarbons] is my favorite. If I had to be stranded any place in the solar system I would choose to be stranded on Titan, because I could fly.
I know that your search is for a different kind of life than the kind that are typically represented in sci-fi—and culture more broadly, really—that are mostly imagining intelligent life. What's your opinion of groups like SETI or of the search for extraterrestrial life that is explicitly looking for other intelligences?
Oh, I'm all for it. Why not? We have to pay attention. Somebody had a great quote that was like "the proof that intelligent life does exist is that they haven't spoken to us," because we're just not ready. Obviously, probably, it verges on the realm of fiction, and it doesn't get the credibility it deserves. But the scientists who are working on it are more than credible. They're rock stars in their fields. You've got to look.
"The irony of [colonizing Mars] is that we've learned from the way that we've messed up Earth, how we could warm up Mars and make Mars more habitable."
You also have an interest in terraforming, right?
Well, it starts off with Mars gardening. We want to live on Mars, we do want to send scientists there—we don't want to make it a short trip. How are we going to do that? So I wanted to figure out, can we garden on Mars? It's covered in soil. Is that all we need? You've probably seen the film The Martian—it's not far off.
Terraforming is just one more step. It will take probably thousands of years. The irony is that we've learned from the way that we've messed up Earth, how we could warm up Mars and make Mars more habitable. We would need to put more CO2 into its atmosphere, to thicken the atmosphere. We could use CFCs [chlorofluorocarbons], but we could probably want to use CO2 instead. And that would thicken the atmosphere, and then as soon as the atmosphere starts to thicken, it'll start to warm up. So then all the ice will start to melt, and lots of CO2 is trapped in the ice, so the melting will release more CO2 into the atmosphere. And then once you start to melt the ice you've got liquid water and you can start to grow plants. And once you start to grow plants you start to release oxygen as a byproduct, and then the atmosphere starts to get oxygen in it. We do think that you could start to enact that in a small reactor and dot them around the planet and start popping stuff in.
The moral question is: Do we have the right to do that? Should we do that? We never will have explored every single inch of Mars so if there is that one microbe holding out somewhere and then we start to change its environment, then that's planetary genocide.
I love this idea that you bring up in the book, that a very intelligent and very successful civilization might have to leave a smaller footprint on its planet, and therefore be harder for us to spot.
Yeah, that's the hopeful thing. To find an industrialized civilization we know exactly what to look for: CFCs, lots of CO2, all the stuff that we're doing. Which teaches us a lot about what to look for. But if they're more intelligent than us, and they've got past that, we wouldn't necessarily find them because they're living harmoniously and nicely about their world.
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Goldilocks and the Water Bears: The Search for Life in the Universe by Louisa Preston is in bookstores and online from Bloomsbury.