Short Wave - Venus And Earth: A Tale Of Two 'Twins'

Episode Date: March 20, 2023

Planetary scientists announced some big news this week about our next-door neighbor, Venus. For the first time, they had found direct evidence that Venus has active, ongoing volcanic activity. "It's a big deal," says Dr. Martha Gilmore, a planetary geologist at Wesleyan University. "It's a big deal in that there are no other planets, actually, where we've seen active volcanism." (Moons don't count - sorry Io!) What makes that fact so striking is how inhospitable a place Venus is now – crushing pressure, a toxic atmosphere and a surface temperature around 850 degrees Fahrenheit. So, what happened? How did Earth and its closest sibling diverge so sharply? On today's episode, Martha talks with scientist in residence Regina G. Barber about what studying Venus can tell us about the past and the future of our own planet. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, Shortwavers, it's Regina Barber, scientists and residents. We just had some big news about our next-door neighbor, the planet Venus. A team of scientists announced they found direct evidence of active volcanic activity, which is pretty cool, right? It's a big deal. It's a big deal in that there are no other planets, actually, where we've seen active volcanism.

That's Dr. Martha Gilmore, a planetary geologist at Wesleyan University. She wasn't part of the study, but she's definitely paying attention. I'm a Venusian. So those of us who study Venus, we are Venusians. That's how we separate ourselves from the Martians. She says the new data shows a brand new volcanic caldera, forming over a course of just a few months. And if it proves out, that will be a first.

So Io has a lot of active volcanism. And the moons of Jupiter, they're puffing like Enceladus, and they're puffing away. But those are moons. Those aren't planets. The Venusians are pretty pumped about this new finding, and about Venus in general. It's considered Earth's planetary twin. It's roughly the same size as Earth and its atmosphere may have once been similar to ours. What we think the solar system was like four billion years ago, if you were to come in as a little alien and visit the solar system when it was a young solar system,

is that three terrestrial planets, Venus, Earth, and Mars, all should have had water on them, all should have had oceans. That means Venus may have once been habitable, which is wild because these days it's a very inhospitable planet with an extremely thick atmosphere, and that makes it challenging to study. We can't use cameras, conventional cameras. We have to use radar. Why can't we rove on Venus? Because it's 450 degrees Celsius and 92 degrees. bars of pressure. So it's like being under a kilometer water and really hot at the same time, which is bad for spacecraft. So what happened? How did Earth's one-time twin turn out to be so different? Today on the show, what studying Venus can tell us about the past and future of our own planet? I'm Regina Barber, and you're listening to Shortwave, the Daily Science podcast from NPR.

So Venus has been shielding its secrets from us under a thick, toxic atmosphere, but Martha Gilmore says the world under these clouds is full of fascinating stuff. And, fun fact, almost every feature on Venus is named after a woman. There are shallow valleys named after Susan B. Anthony and Marlena Dietrich. It's actually slightly more goddesses and made-up women than it is, actual living women. and I think that is also just a testament of how history is written. So you'd mentioned earlier that like Earth and Venus are similar. Like what does it mean to say that Earth and Venus were twins at one point?

Planets come out of star dust. And so we all start out with the same composition as our sun is our star. And then how we all start out hot. And then how long we stay hot is a function of how quickly we cool off, which is a function of size. So Venus and Earth are the same size. They are still hot. They still have heat from the beginning. They still have radioactive heat. Heat means they have volcanism. Volcanism is what maintains atmospheres and geologic activity and allows planets to be habitable. So tell us more about the habitable zone. Like where is it and has it always been in that location in our solar system? Yeah. So the habitable zone is defined as being where liquid water is stable. We're sort of a medium zone.

star than the habitable zone is in the Venus to Mars range. And most stars are dim and cool, cooler than ours. And so the habitable zone, when the star was young, was closer to the sun, close in the Venus range and Earth, and has been moving outward with time. And the Venus climate is thought to have been able to maintain liquid water for perhaps billions of years. So then what happened? If we all started, if Earth and And Venus, and to some extent, even Mars was terrestrial. Like, it had water. What happened?

What happened? Right. That's what we want to understand. So, Mars, it cooled off and its volcanoes turned off. And that's the way you maintain an atmosphere. It's kind of like the three bears. And Venus was closer to the sun. And so it lost water because of having a higher temperature as the solar system evolved.

and once water goes and leaves the system, you can't get it back. So, and then Earth, we're the just right part. We're the place where our carbon dioxide is locked up in rocks via a chemical reaction between the oceans and weathering on Earth. And so that allows us, instead of having a big massive carbon dioxide, rich atmosphere like Venus, the corals and the limestones and all those little creatures on earth, they scrub the carbon dioxide out of our atmosphere into our oceans and keep our temperatures low. So is that why the atmosphere of Venus is so much more like intense? Can you tell us a little bit more about the differences between our atmospheres, Venus and Earth? Yeah. So Venus's atmosphere is dominated

by carbon dioxide. It's like 95% carbon dioxide, which is what our atmosphere was like, too, at the beginning. That's what you make a planet to get away from that, you need to do something. And what happened on Earth were two things. We had the evolution of life, sucking down carbon, photosynthetic life, and the oceans and this cycle I just described of taking CO2 out of the atmosphere and storing it and rock in the oceans. So if you took all the carbon-rich rocks on Earth, the carbonate rocks, like all the limestones and all the corals, and you like poof them into vaporize them and put all that CO2 back into the atmosphere, that would be about 60 times more CO2 than we have now. And what Venus has is 90 times what we have today on Earth. So it's,

it's not that much different, right? If you have that ocean, you suck it down. And without that ocean, without our ocean, if we lost our ocean, that CO2 would go back into. the atmosphere as well. So how can studying Venus like help us better understand and mitigate and deal with climate change? Yeah. Yeah. Well, we have right next door an example of a Earth-sized planet with a massive greenhouse atmosphere. One of the missions that's going to Venus in late 2020s is Da Vinci, which is a probe and is going to go through the atmosphere and measure the chemical composition of the Venus atmosphere. That gives us a baseline for understanding the origin of Venus's atmosphere, how it relates to the other planets and Earth. And I think that we're starting to

understand as a society that climate does not run in a linear fashion. It's like, okay, things are running along. And then they ramp up really fast. And then you get into this other phase of being or a phase of chemistry. So then could Earth turn into Venus at any time? Sure. Well, not at any time, not tomorrow. Not tomorrow. But yeah. If we somehow interrupt the cycle, I mean, corals, all the little creatures in the sea, they are part of that cycle too. And so if we're interrupting them by acidifying the ocean, they can't build their shells, we're losing a part of the carbon sink that is available to us to keep our carbon levels low. So all of these things are connected and studying Venus will help us understand how much is too much, how the other castas are involved.

Tell me about an upcoming mission to Venus that you're excited about. What questions do you hope these upcoming missions will answer? So I have to be honest. I'm one of the lucky few to be on team member for both Ferratas and DaVinci. And so from a chemistry point of view, the data from DaVinci are absolutely essential because that's how we start understanding how planets, where planets start and how they evolve. You need that chemistry. And the chemistry of Venus does all kinds of things that don't happen on other planet. Da Vinci also has a camera on it. And so we're going to look at descend over a part of a region on Venus that contains some of the oldest rocks. And so we're going to look at descend over a part of a region on Venus that contains some of the oldest rocks and we'll see it not at radar wavelengths,

but like almost close to what we would see with our eyeballs. So I'm really excited to just see the rocks with my eyes. Because you haven't been able to. Right, because I haven't been able to. Like as a human, as a geologist and be like, oh, there they are. But that's just one part. The reason why Veritas is so exciting is because it's going to map all. of Venus at this scale that will just, it's going to blow our minds because of the things that we will be able to see. It's like a completely new paradigm for how we understand Venus. So let's actually get back to the active volcanism study. Do they shed light on any of the questions you're asking now? Active volcanism tells us about heat moving from the interior to the exterior of the planet. And with that heat, we're bringing volatiles and putting gases into the atmosphere. And all of that, it also tells you you're making new rock. And it tells you that you're actively making

new atmosphere to change those rocks over time. And I know this sounds like, you're like, who cares? But that's like the whole system. I mean, it's what we do on Earth. Our system, the stuff that comes out of volcanoes, a lot of that is water. And because there's so much water, we're like, who cares? There's water. But water is what dominates all of the cycles on Earth, like all of the life cycles, all the geochemistry. And so that confirmation of volcanism, it allows us to like move on from this question and start to think now what are the consequences of that. So personally, I'm really, I want to understand the oldest rocks on Venus. I'm very, that's my specialty. And I really want to know if they have evidence of water in their.

recorded in the composition of the rocks, which we'll be able to do for the first time with these missions. And this is our first step to going down and landing on rocks or even returning rocks from Venus that come from that time when it was a habitable Earth-like planet. So that's what I'm jazzed about. I mean, I just, if the, ah, I mean, Venus, look, look, Martians, I'm pointing at you, Martians out the door. Look, Venus had an ocean longer than Mars, probably. I mean, that's what we think right now. So thinking about like, you know, little creatures floating around and, you know, the Mars creature's like, oh, my God, I'm got it. I'm so dry. And Venus is like, we're fine, we're fine. We're here. So I want, I want those rocks. That's,

that's what we want to get out and see if we can find them. So that's what I'm excited about. And then I'll just say one more thing. Yes, please. Go to like, there is actually a Google Venus and, I don't know. Like on the Twitters, there's like Venus nerds or like Venus picture of the day or whatever. But I just encourage, just take like five minutes and just like look at a high resolution

image of Venus from Magellan and just look at all the volcanoes and the flows and the it's just beautiful. It's just volcano after volcano. And as the discovery today just show, we're barely scratching the surface of

understanding what's down there on this large, gorgeous active planet. So, yeah, get your Venus on. And when you go outside and it starts to get dark and there's no clouds, that first star you see, what is it? Oh, that's Venus. It's Venus. It's Venus. Yes. Yes. As I say, I blow her kisses when I see her because she's just amazing. Thank you so much. This has just been wonderful, joyous. You are so welcome. And you're every, you're from to jump. The week we spoke, the federal government announced a setback for one of those missions to Venus, the Veritas mission. It's been slashed by $122 million, which makes it very unlikely to happen in the near future.

But the probe mission, Da Vinci, is still in the work. This episode was produced by Thomas Liu, edited by Gabe. Spitzer and fact-checked by Anil Oza. Our audio engineer was Patrick Murray. Brendan Crump is our podcast coordinator. Beth Donovan is our senior director of programming, and Anya Grunman is our senior vice president of programming. I'm Regina Barber.

Thanks for listening to Shortwave from NPR.