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Science Friday

Looking for life in the clouds of Venus

03 Jun 2026

Transcription

Transcript generated automatically by AI and may contain errors.

Chapter 1: What motivated researchers to explore life in the clouds of Venus?

3.271 - 26.916 Ira Flatow

Hi, Ira here, and you're listening to Science Friday. Dr. Sarah Seeger has made a career out of looking for signs of life in outer space, searching for exoplanets thousands of light years away. But now Dr. Seeger has come home, sort of. She has turned her attention to our neighbor, the planet Venus. At first, it would seem like an unlikely place to look for life.

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26.896 - 29.539 Ira Flatow

Its surface temperature is hot enough to melt lead.

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Chapter 2: What are the extreme conditions on Venus and how do they affect the possibility of life?

30.02 - 47.301 Ira Flatow

It has a smothering carbon dioxide atmosphere, all topped off with sulfuric acid clouds. But Dr. Seeger thinks it might be possible for some form of life to survive there, not on the planet's surface, but up in those clouds.

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47.281 - 66.042 Ira Flatow

Dr. Sarah Seeger is an astrophysicist, planetary scientist at MIT, and part of a team leading a proposed series of missions to Venus to sample those clouds for evidence of life. Welcome back to Science Friday. Thanks, Ira. You know, when I list the conditions on Venus, life doesn't seem likely.

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66.103 - 72.271 Ira Flatow

The idea that life might exist in the clouds there, where does that come from and why are you hopeful about that?

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72.951 - 97.747 Dr. Sara Seager

Well, first, the way you listed what it's like in the Venus atmosphere, it doesn't sound too friendly to me either. So, yes. Well, when we think about what life requires, if we want to truly boil down to the fundamentals, there's just a few things. One is temperature, the right temperature for covalent bonds, so complex molecules of the kind life needs to use can form. The second is energy.

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98.187 - 106.439 Dr. Sara Seager

And of course, there's energy from the sun on Venus. And the third is a liquid environment, liquid so that chemical reactions can happen.

106.8 - 106.92

Right.

107.525 - 128.516 Dr. Sara Seager

So if you just boil it down to that, Venus does have what we require. And although the surface, as you pointed out, is so hot, hot enough to melt lead, just like here on Earth, if you hike up a mountain or go on an airplane, it gets colder and colder as you go above the surface. And the cloud layers with the liquid are the right temperature for life.

129.538 - 138.647 Dr. Sara Seager

And this is why, over half a century ago, Carl Sagan first put out the idea, based on these fundamentals, that perhaps... there could be life in the clouds of Venus.

139.709 - 143.454 Ira Flatow

How would that life form be? Would it be the kind of life we have here on Earth?

Chapter 3: How does Dr. Seager justify the potential for life in Venus's atmosphere?

180.349 - 183.313 Ira Flatow

Now, how would you know that, that life exists there?

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183.715 - 199.032 Dr. Sara Seager

Well, we don't know if life exists there. And this is like the billion dollar question that everyone has of how do we know if there's life anywhere? And at the moment, what scientists are doing is they draw a dividing line. in chemistry.

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199.533 - 221.289 Dr. Sara Seager

And on one side of the line are the kinds of basic molecules that nature provides, like from photochemistry or from volcanoes or minerals or just chemicals that are just present. And on the other side of that line are incredibly complex molecules. so complex that we think only life could make the molecules.

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221.629 - 233.45 Dr. Sara Seager

And therefore, one of the main ideas is if we can find complex molecules, we can infer the presence of life. The only problem is where do you draw that line? And also that line keeps changing.

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235.033 - 241.144 Ira Flatow

Is it possible to sort of experiment to create the kind of life you might see in those clouds?

242.288 - 267.435 Dr. Sara Seager

Well, I would say yes and no. I mean, if you think about it, people are trying to create life on Earth in the lab, like life that may have arisen here on Earth first early on in water, and scientists still haven't been successful at that, although they've been successful in many separate areas in the formation and origin of life. So we can repeat those same experiments.

267.415 - 287.836 Dr. Sara Seager

Like, for example, here on Earth, in the laboratory, people take lipids, like fats with heads, like polar head groups, and they put those in water to try to form little compartments, vesicles. We can't say primitive cell membrane, but that's to get the idea, like little tiny spherical vesicles, you know, because all of our life has compartments.

288.256 - 297.085 Dr. Sara Seager

So we can copy some of those ideas and we can try to find materials that are stable in concentrated sulfuric acid, what the Venus clouds are made of, and we have done that.

297.638 - 299.842 Ira Flatow

Tell me about that. What do you mean you have done that?

Chapter 4: What experiments are being conducted to understand life in Venus's clouds?

924.137 - 945.082 Dr. Sara Seager

I lived through a time when people kept telling us the field was going to dead end. But if you work in the field and you're deep in the trenches and you see all the possibilities flourish, then you know it's possible. Like, I can't guarantee that the biomolecule complexity won't dead end in sulfuric acid, but everything so far shows it's a go.

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945.202 - 948.626 Dr. Sara Seager

And we're going to keep following this and keep on doing it.

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949.748 - 962.263 Ira Flatow

You know, what we hear most of the time from scientists is that people will ask them, and I've asked this question over and over again, what practical value does any of this have for us? And how do you answer that?

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962.665 - 979.257 Dr. Sara Seager

Yes, well, I've given this a lot of thought, actually. And I'm about to make a big move from my current job at MIT in the USA to Canada, to the University of Toronto. And Canada is really, really pushing people and encouraging everyone to think about that question.

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980.317 - 1000.757 Dr. Sara Seager

So one thing is that when we want to go to Venus to search for very specific organic molecules, complex organics, but a long list of them, because we don't know what we're looking for, there are a number of miniature molecular sensors being developed in this area. We're developing one in my lab. Other ones like carbon nanotubes are out there.

1000.797 - 1017.737 Dr. Sara Seager

And we're taking all these and we're trying to accelerate their development and usage in terms of their robustness in the field And a more complicated thing to explain is selectivity. Like how do you know you found the molecule that you're targeting? And these have a lot of different uses. They can be used for chemical threat detection.

1017.818 - 1041.744 Dr. Sara Seager

They may have uses in agriculture and medicine in a lot of areas. So it is kind of rare, but it happens that in space science, we invent something or we build things like medical imaging and Even GPS came out of people experimenting with rockets. But I do see a way, a path to making that more purposeful.

1042.665 - 1058.627 Dr. Sara Seager

These crazy questions we're asking in the search for life, in the origin of life on Earth, in exoplanets, in space science, we really have to push the envelope. Because we're going to extreme environments, we need more decimal places than we traditionally use here on Earth.

1059.208 - 1072.547 Dr. Sara Seager

So there is room for pushing the envelope in astrobiology and in science, but purposely finding and exploiting and executing the impactful relevance we could have in society.

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