Brainstorm: Looking for life among the stars
April 25, 2022
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Far from the lightspeed space travel of science fiction, real-life astrobiologists apply disciplines ranging from computer programming to molecular analysis in order to study alien life. The Daily spoke with three scientists to ask: How are we looking for life beyond Earth?
SHANE LARSON: Of all the natural wonders of the world, the sky is the one thing that almost everyone’s been exposed to, no matter where you live. The sky evokes in all of us a very kind of deep sense of ‘There is something bigger.’ And humans, for whatever reason, are wired to wonder where we came from, and what our purpose is, and all of those sorts of things.
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AVIVA BECHKY: That’s Northwestern Professor Shane Larson. He’s a gravitational physicist, and this quarter he’s teaching a class about aliens — or, more technically, about astrobiology. But what even is astrobiology?
SHANE LARSON: It’s a relatively new branch of astronomy, which attempts to blend lots of different areas of science together to answer a very fundamental question, which is, is there life elsewhere in the universe? What are the chances life might be there? What might it be like? And how could we go about discovering if it’s there or not?
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AVANI KALRA: From The Daily Northwestern, I’m Avani Kalra.
AVIVA BECHKY: And I’m Aviva Bechky. This is Brainstorm, a podcast exploring all things science, health and tech. In this episode, we’re setting off at warp speed to learn how scientists study aliens.
AVANI KALRA: Astrobiologists come to the field from very different backgrounds. There’s Larson, a physics professor by training —
SHANE LARSON: We wrote a paper that said, if you were on a starship powered by a Miguel’s warp drive, and you looked out the window, what would the universe look like?
AVIVA BECHKY: — and Lucianne Walkowicz, an astronomer at the Adler Planetarium in Chicago who does work in computer science —
LUCIANNE WALKOWICZ: Space telescopes are just kind of working all the time, and then they beam their data down to Earth. Then you can work on it anytime yourself. So it looks a lot like you know, me sitting at a laptop, which is not tremendously exciting, except for what I’m thinking about.
AVANI KALRA: — and third-year NU Earth and Planetary Sciences Ph.D. candidate Floyd Nichols, who works in organic geochemistry.
FLOYD NICHOLS: My work kind of focuses on looking at biological markers, or biomarkers for short, and trying to understand their preservation in very extreme environments on Earth that kind of resemble environments that we would find on Mars.
AVIVA BECHKY: Larson says right now, astrobiology is growing fast. Scientists are beginning to develop more specialized knowledge.
SHANE LARSON: And once the literature gets deep enough, what will happen is, there will be very obvious, let’s call them islands, where our knowledge is incomplete. But we have enough capability or we have enough skills or enough technology that we can address those particular questions. And when that happens, people glom on to it, and they all start working on it. And we start to produce more knowledge in that specific area.
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AVIVA BECHKY: When you think of aliens, you might imagine pointed ears and slanted eyebrows. Or perhaps you picture an overdramatic liar in reptilian makeup with an indent the shape of a spoon on his forehead. Or — well, maybe I’ve just seen too much Star Trek.
SHANE LARSON: Most science fiction movies resort to what’s easy, right, which is you know, you can dress you and I up and the aliens kind of look humanoid.
AVANI KALRA: In reality, scientists studying life elsewhere are usually looking for something completely different. Often, something microscopic.
AVIVA BECHKY: Nichols conducts his research on hypersaline lakes in British Columbia. He looks at lipids — which you might remember from high school science classes. We typically call them fats.
FLOYD NICHOLS: Lipids come from the cellular membrane, and different organisms produce different types of lipids. And that can be diagnostic for life in general, but also for some specific life forms.
AVANI KALRA: Nichols said lipids are a lot like DNA.
FLOYD NICHOLS: And what I mean by that is you can sequence DNA, and you can very accurately say, ‘Okay, this belongs to this specific type of organism,’ or ‘this belongs to this specific type of organism.’
AVIVA BECHKY: But they’re a little less specific. Instead of telling you which exact organism it belongs to —
FLOYD NICHOLS: A lipid will say, this lipid belongs to this class of organisms. So this belongs to microbacteria, or this belongs to humans, or this belongs to plants or something like that.
AVANI KALRA: Essentially, by identifying lipids, Nichols is able to determine what kind of organisms live in hyper-saline bodies of water. But what does that have to do with space?
AVIVA BECHKY: Well, the lakes he studies have a unique type of salt: magnesium sulfate instead of sodium chloride. Scientists think that salt is common in the water that used to be on Mars.
FLOYD NICHOLS: Mars didn’t lose its water all at once. It lost it slowly over geologic time. So, you know, a billion year timescale or so. And towards the later end of Mars, so roughly 3.7 billion years ago, is when water would have been pretty saline. So, very similar to some of the environments here on Earth.
AVIVA BECHKY: Since it’s likely Mars once had salt-filled rivers and lakes, Nichols looks in those environments on Earth.
FLOYD NICHOLS: The lakes I look at in British Columbia have a very, very unique composition for magnesium sulfate waters, which is very rare on Earth, but not so rare on Mars.
AVANI KALRA: When Nichols detects single-celled organisms in magnesium lakes on Earth, he then knows they could survive in similar conditions on Mars. These organisms are called “extremophiles” — they’re the basis for a lot of the investigation into extraterrestrial life.
FLOYD NICHOLS: The importance of understanding the preservation of these molecules is it will give us a better understanding of how life signatures might have been preserved — if they existed at all — on Mars or elsewhere in the solar system.
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AVANI KALRA: While scientists like Nichols study life here on Earth, Walkowicz looks to the sky. Part of their work involves looking for exoplanets, or planets that orbit stars outside our solar system.
AVIVA BECHKY: We can’t directly see exoplanets from our solar system. But we can see stars — and based on the stars’ patterns of light, we can guess whether planets are orbiting them.
AVANI KALRA: When a planet crosses in front of the star, the star dims a bit. So, if a telescope detects a star that regularly changes brightness, scientists might conclude that there’s an exoplanet there.
LUCIANNE WALKOWICZ: I often compare this to like, if you’re in a movie theater, or watching a movie, and somebody like walks in front of the screen, blocks some of your light from getting to you, right?
AVIVA BECHKY: Based on the light patterns, scientists can guess the size of the planet and how far it is from the star. Scientists often look for planets in the habitable zone, where they’re the right distance from the star to have liquid water.
AVANI KALRA: Scientists didn’t know for sure that exoplanets existed until 1992. But people have been imagining them way before then.
SHANE LARSON: Science fiction is actually a great tool for astrobiology, right? Star Trek came out in the 1960s. Star Wars came out in 1977. They had planets around other stars, right? That was 30 and 40 years before we knew with certainty, with any scientific evidence, that there were planets around other stars. Right? That’s, that’s the awesome beauty of science fiction is, you know, it captures what we think. Maybe it’s true, maybe it’s not. But as science catches up, we discover, ‘Oh, it’s true! There are planets around other stars.’
AVANI KALRA: As science fiction developed, technology did too.
AVIVA BECHKY: While writers invented otherworldly ways of communication for fictional alien species, astrobiologists continued to look for something that resembles our own methods of communication.
SHANE LARSON: We’ve developed technology, like radio telescopes, cell phones, satellites, laser beams, whatever, that we can communicate with.
AVANI KALRA: The idea is that civilizations in space would have evolved tech similarly to our own technology —
SHANE LARSON: — Not because we think they’ll make an iPhone on their world, but because the laws of physics are immutable.
AVIVA BECHKY: A lot of the technology is based on radio waves.
SHANE LARSON: And radio light is something that a technological civilization that understands atoms will encounter. And because they encounter it, they may, they will develop a technology to detect it. And if you have the technology to detect it, you have the technology to transmit it.
AVIVA BECHKY: Walkowicz also works on SETI — that is, the search for extraterrestrial intelligence. Part of SETI research involves searching for signals that could have been sent by alien technology.
LUCIANNE WALKOWICZ: All of the early SETI searches were about looking for radio waves. And radio waves, you know, it was not an accident. Like, the original concept for looking for extraterrestrial intelligence through radio emission was because human beings used radio to communicate with each other.
AVANI KALRA: Scientists used to look for radio signals that an alien civilization could have transmitted. But as Earth got more technologically advanced, we used radio waves less and less. So Walkowicz approaches the search for life a little differently.
LUCIANNE WALKOWICZ: We don’t really know what some other consciousness out there in the universe would choose to do as far as communication. So instead of trying to apply what humans do out to some other intelligence — instead, the idea was to look for the strangest things that we observe in astronomy, and then to see whether any of those would be not explicable through astrophysical phenomena that we already know about.
AVANI KALRA: Maybe, just maybe, the strange readings Walkowicz looks for were created by an alien intelligence.
AVIVA BECHKY: Boyajian’s star is one example. Its light flickered in ways astronomers didn’t initially know how to explain.
AVANI KALRA: A theory that got a lot of press was the idea that an alien species could have built a Dyson sphere — an engineering project the size of a solar system. When such a sphere orbited in front of Boyajian’s star, it could block the light in atypical patterns.
LUCIANNE WALKOWICZ: To the best of my knowledge, nobody in astronomy currently believes that Boyajian star is surrounded by a Dyson sphere. But, you know, it’s I think a testament to people’s creativity that if we can think of it in science fiction, then maybe it is something that we would do some thousands of years from now.
AVANI KALRA: Beyond exoplanets and SETI, Walkowicz is now moving into a completely different area of astronomy –– the ethics of space exploration.
LUCIANNE WALKOWICZ: I have been thinking a lot about the sort of social impacts and their intersections with astronomy. This is a topic that I’ve given a lot of talks about in the past, which is the intersections of policing and astronomy.
AVIVA BECHKY: Walkowicz spoke about a fair in Dubai that presented a ‘Mars Science City’ placed in the desert —
LUCIANNE WALKOWICZ: It was framed as this amazing research base for living on Mars. But also, the police were like, ‘Well, here are these self-driving, automated policing vehicles that will also live in the Mars Science City.’
AVANI KALRA: Walkowicz says we have to carefully consider how we use space to shape the way we understand future possibilities.
LUCIANNE WALKOWICZ: And so sometimes these sort of sci-fi or futuristic contexts are ways of extending punishment and carcerality to our future, using space as this kind of like backdrop.
AVIVA BECHKY: Walkowicz said it’s important to be aware of how our inequities affect space exploration. They also think if we do find life, chances are it’ll be closer to home.
LUCIANNE WALKOWICZ: Our best chances for finding life beyond Earth, I think, are probably within our own solar system.
AVANI KALRA: They said they love the research being done on exoplanets. But their distance from Earth just makes finding life less practical.
LUCIANNE WALKOWICZ: When we talk about places like Mars, or Europa, we have not only all of the tools of remote observing, you know, looking at things from afar, but we also have the ability to send rovers and landers to the surface. And that means that we can use a lot of the tools that we use to characterize our own planet, on those other worlds, just because they’re close to us.
AVIVA BECHKY: The best way to find intelligent life might be up for debate, but the concept that it’s out there remains compelling.
SHANE LARSON: The idea that there are other intelligent lives on the universe, on the planet that, that have things to think about that I don’t think about. I like that. I would love to know what the pilot whales are talking about, but they’re doing their pilot whale-y business, and they don’t care if I know or not, right?
AVANI KALRA: Still, many scientists like Larson, Walkowicz and Nichols would love to see one thing happen.
LUCIANNE WALKOWICZ: I hope we find some freaking aliens.
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AVANI KALRA: From The Daily Northwestern, I’m Avani Kalra.
AVIVA BECHKY: And I’m Aviva Bechky. Thanks for listening to another episode of Brainstorm. This episode was reported and produced by Avani Kalra and myself. The audio editor of The Daily Northwestern is Lucia Barnum, the digital managing editors are Will Clark and Katrina Pham and the editor in chief is Jacob Fulton. Make sure to subscribe to The Daily Northwestern’s podcasts on Spotify, Apple Podcasts or SoundCloud to hear more episodes like this.
Email: [email protected]
Twitter: @avivabechky
Email: [email protected]
Twitter: @avanidkalra
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