10/09/2020

Solar System Smackdown: Mars Vs. Venus

29:20 minutes

an illustration of the planets mars and venus, anthropomorphized with sneering faces and arms raised with blue boxing gloves on, floating on a black space with white dot stars background. the words "mars vs venus" are written between them
Illustration by Elah Feder

One of the fiercest hunts in the solar system is the scientific search for signs of extraterrestrial life—whether that’s in a methane ocean on Titan, under the icy crusts of Europa or Enceladus, in newly discovered subsurface salty lakes of Mars or, in the case of hypothetical long-dead fossils, in the rocks of ancient Martian river deltas.

But just as the next Mars rover—equipped with life-sensing instruments of all kinds—is barreling toward the Red Planet for a February landing, comes news from another planet. A research team writing in Nature in September say they’ve found high concentrations of phosphine in the atmosphere of Venus. That much phosphine is not known to exist without help from bacteria—and researchers dating all the way back to Carl Sagan have suggested that the thick, acidic clouds of Venus would be a plausible place to harbor microscopic, extreme-loving life.

Is this a good reason to send more missions to Venus? Or is Mars still the best candidate for investment of finite resources? Science Friday producers Katie Feather and Christie Taylor host this completely made-up argument about which planet is the best bet for finding life, with help from genetics and astrobiology researcher Jaime Cordova, and planetary scientist Briony Horgan.

Watch these fierce competitors face off in front of a live Zoom audience!

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Segment Guests

Jaime Cordova

Jaime Cordova is a Ph.D. candidate at the University of Wisconsin-Madison in Genetics with a minor in Life Sciences Communication. His research focuses on studying how bacteria (such as E. coli and Salmonella) respond to varying oxygen levels and the genetic foundations behind those responses, and how those genetic foundations have evolved. Additionally, Jaime is interested in understanding if life can exist in other worlds, especially the clouds of Venus.

Briony Horgan

Briony Horgan is an associate professor of Planetary Science at Purdue University in West Lafayette, Indiana.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, the mysterious case of the vanishing freshwater mussels but, first, a little bit of healthy competition around the SciFri office is a good way to blow off some steam during these trying times and usually leads to some fun, nerdy arguments. Well, a few weeks ago, new research about two of our planetary neighbors got a few of our producers fired up– Katie Feather and Christie Taylor got together to hash things out in front of a live Zoom audience, and well, let me just say, there were no chairs thrown.

KATIE FEATHER: Thanks, Ira. Hey, Christyie.

CHRISTIE TAYLOR: Hey Katie. Thanks for coming by all of our computers today.

KATIE FEATHER: No problem. Thank you so much, everybody, for joining us via Zoom. Christie, you need to explain to the people here today why we’re together in this segment today.

CHRISTIE TAYLOR: Well, that’s a great question, Katie, and it all started with a little bit of an argument, which is, which planet should we, we personally, the staff of Science Friday who get to travel to other planets as you know, where should we go to look for life? Mars or Venus?

KATIE FEATHER: Right because, a couple of weeks ago, we got this news about phosphine being discovered in the atmosphere of Venus, and everybody in the office was like, oh my gosh. And they got so excited about it. And then this news about salty lakes on Mars came out, and people were like, oh yeah, Mars is still around. People are still looking for signs of life there.

CHRISTIE TAYLOR: Yeah, and as you know, I am definitely on team Venus. I’m an underdog person, and I think it’s really cool that this planet that’s been more or less ignored by NASA for so long has had such a striking piece of evidence arise for something that we really can’t explain except possibly with the presence of a lot of little bacteria, swimming around in the cloud, burping out this poisonous gas phosphine.

KATIE FEATHER: OK, but I’m just someone who doesn’t really like a lot of excess hype around something that maybe doesn’t deserve it. There’s a reason why we started our search for life with the red planet. For one, it’s much more Earth like than Venus, which is basically a hell hole. It’s 698 degrees Kelvin on the surface. Two, there’s a lot of very reasonable hope for living bacterial life on Mars in places like under the polar ice caps of Mars and in these new salty lakes.

CHRISTIE TAYLOR: I don’t know that Earth really wanted to be a part of this argument, but since you’re bringing Earth into this, you know that Venus and Earth are basically twins, right, just slightly different more hellish conditions? Venus is hot. It’s high pressure now.

But it’s partly because Venus had this runaway greenhouse effect until the atmosphere was literally soup, which I don’t know if that sounds familiar these days or not. So what that tells me is that if we find life on Venus, we’re also finding out something about a potential future that Earth could be dealing with and the kinds of life that may thrive in that future.

KATIE FEATHER: OK, here’s my counterpoint to that. Since Mars is similar to ancient Earth, we can also observe what climate change has done to Earth by looking for signs of ancient life on Mars in rocks, which Mars has and Venus does not have. And you cannot understand your future, Christie, unless you look and understand your past.

CHRISTIE TAYLOR: I’m hearing a lot of fear of the unknown. I’m hearing a lot of hesitancy about trying something new, and I don’t think that’s a good rationale for making decisions about scientific exploration. Aren’t we supposed to dive into the unknown and be excited to discover things that we can’t see or explain from here? It just– it feels too safe to be looking at Mars, honestly.

KATIE FEATHER: It’s not necessarily safe. it’s just like I’m more of a completist, so I feel like we haven’t completed the job of Mars and found everything that we need to find. And in terms of scarce resources, and manpower, and time, and things like that NASA has, I feel like we just need to kind of wrap up our exploration of Mars before we move on to other more quixotic projects like exploring Venus.

CHRISTIE TAYLOR: Katie, it’s not quixotic, though. The European Space Agency has a craft that’s flying by Venus in like a week, so we may even have more data without having to do anything new, even sooner than we’ll have anything from Mars, which, by the way, perseverance isn’t even getting there until February.

KATIE FEATHER: OK, well, I’m OK with the concept of– you know the meme with the girlfriend and the boyfriend and the boyfriend’s looking back at the other girl. I’m really cool with sticking with Mars, sticking with the one you know, and then the other girl– and that meme can be Venus, and the dude’s just looking back at it being like, hey, what’s up back there? Just checking out the situation back there but, really, sticking with Mars, the one you know.

CHRISTIE TAYLOR: Katie, are you calling me a distracted boyfriend?

KATIE FEATHER: Yes, distracted boyfriend meme. That is what the situation is. What meme is your planet like, Christie?

CHRISTIE TAYLOR: My planet is not like any meme, Katie, but if you want a pop culture reference, we do have Carl Sagan on our side. He was proposing back in 1967, more than 50 years ago, that we should be considering the clouds of Venus as a potential habitat for microbial life forms. And who are we, Katie, to disagree with Carl Sagan?

KATIE FEATHER: Well, there might be a reason why we didn’t follow Carl Sagan’s advice all the way back then. But I’m just saying. It’s unlikely we’re going to be able to answer this question without pursuing both planets, which we’re probably not going to be able to do with equal vigor and seriousness. So the question is, do we switch tacks and learn more about the signs of life on Venus? Or do we stay the course and persevere– get it, Kristie– with Mars?

And we’re just going to have to imagine that NASA’s out there listening to this debate because we don’t actually control the funding over there or have anything to do with their decision making. But we’ll pretend that they care about what we have to say.

CHRISTIE TAYLOR: I know NASA’s listening in my heart, and I’m sweating a little bit.

KATIE FEATHER: Well, you don’t need to sweat because the whole point of this conversation that we’re having right now is that we need help from experts to help us make this decision because we’re just science communicators.

CHRISTIE TAYLOR: Yeah, that’s true. So what I’m going to propose, Katie, is that we phone a friend and bring in some friends to help us out.

KATIE FEATHER: Yeah, we’ve each brought a researcher to the discussion to help us argue our talking points in favor of our chosen planet. Joining me is Briony Horgan. She’s an associate professor of planetary science at Purdue University. That’s all the planets because she’s an expert in all the planets, and yet she’s here with me to talk exclusively about how Mars is great and why we should be going there to look for life.

CHRISTIE TAYLOR: All right, Briony. Nice to meet you. You seem pretty cool. I am going to bring in my friend, and his name is Jaime Cordova. He is a PhD student at the University of Wisconsin-Madison in genetics but also astrobiology, and this will be important later. Stay tuned. He is also, as of 2019, a solar system ambassador for NASA’s Jet Propulsion Laboratory, so that’s an ambassador for the solar system. So I would say he is also pretty cool.

KATIE FEATHER: OK, welcome both of you to the show. Thanks for talking some smack with us.

JAIME CORDOVA: Thanks for having us.

BRIONY HORGAN: Great. Thanks for having me. This is great.

KATIE FEATHER: OK, so Briony, we’re going to start with you. This whole argument started because of new research about both these planets, so why don’t you give us the case for Mars with regards to these salty lakes?

BRIONY HORGAN: Yeah, well, so on Mars, we have a lot of evidence that there might be liquid water that’s stable at or near the surface of Mars today, and that new salty lakes study is a great example because it’s a new result showing that there might be ponds of liquid water under the South polar ice cap of Mars, which could be a habitable environment that life could live in today, which is really exciting.

KATIE FEATHER: So how would we know, though? what. Would we need to kind of do to see if those habitats were conducive for life and if there was life actually there?

BRIONY HORGAN: We’ve got to go, right? That’s the whole– we got to go and explore. So it’d be awesome to go send a drill or something to the South polar cap. It’d be great to go look at some of the sediments and things that are coming off of the South polar cap to see if there’s anything there, something we could definitely do with the kind of technology we have today.

CHRISTIE TAYLOR: OK, very good point, but I really want Jaime to step in into my corner, in the Venus corner, and talk more about this phosphine finding, which was pretty exciting but maybe not well unpacked for everybody. So why is phosphine such an exciting possibility for Venus, especially when we’re talking about the clouds?

JAIME CORDOVA: First, I’m going to clarify that. The researchers who published the phosphine study made it really clear that the finding of phosphine does not necessarily equal a finding of life. So we haven’t found life yet. That’s for sure.

But the reason why is so interesting is because, at least here on Earth, the only types of chemistry that we know of that can make phosphine is either we make it in a lab or some form of anaerobic bacteria. Even with anaerobic bacteria, we don’t really understand the mechanism that they make phosphine. That was really the reason why the phosphine detection was so exciting.

It’s possible that it could be life. It’s also possible that it could be some form of unknown chemistry that we just don’t understand. Now, the reason why it’s so exciting is because the clouds are actually the area where we feel that life could exist there, and that’s because the clouds, unlike the surface of Venus, which is really a lot like hell, clouds of Venus are a lot more comfortable, at least to some forms of life.

KATIE FEATHER: See, I’m going to agree with you there. The surface of Venus, a lot like hell. You’re not going to find any life there. But then there’s also these clouds, which we can’t see through, and that’s one of the reasons why we chose Mars over choosing Venus to start our search many years ago in looking for life. So Briony, help us understand the many times that we’ve gone to Mars, what have we turned up so far there that’s really promising?

BRIONY HORGAN: Yeah, we’ve actually only gone to Mars once to look for modern and existing life, and that was the Viking Landers back in the ’70s. And since then, we didn’t see any obvious evidence for life because it landed in a dry, dusty part of Mars that we now know maybe isn’t really habitable environment. But since then, NASA’s taken this totally new approach to try to understand when and where life may have existed on ancient Mars, and the when is really important because, as you mentioned before, Mars we think, a very long time ago, billions and billions of years ago, used to look a whole lot like Earth.

At one point in its past, it had rivers, lakes, maybe even oceans that could have been a habitable environment where life could have lived. And so what NASA’s been trying to do for the past 30 years is slowly build up a huge database of knowledge about, OK, first, was there water on ancient Mars? Yeah, we know that. The Spirit and Opportunity rovers showed us that water was present.

Then, OK, were those environments habitable? Well, not just did they have water but did they contain the building blocks of life as well? And that’s what the Curiosity Rover has shown us over the last eight years on Mars, and now, with the Perseverance Rover, now that we know that, in fact, there were these abundant habitable environments all over ancient Mars billions of years ago, we’re actually going there to look for signs of ancient microbial life in the rocks. And so that’s really what the search for life on Mars today is really about is looking for signs of ancient life trapped in the rocks.

CHRISTIE TAYLOR: So we’re talking about ancient life. We’ve sent all these craft looking for ancient life. But I really want to take our attention back to modern life because that seems like where it’s at, and in that case, Jaime, isn’t Venus like overall a better candidate?

JAIME CORDOVA: Yeah, Venus is definitely a better overall candidate in that case. Sure, Venus is hell like, but at least it’s not dead like Mars. [LAUGHS] So sure, you’ve got the salty lakes, but are you really going to be able to access those salty lakes under those poles? And I think some of the other– there is some evidence– there are some models that show that Venus likely had a continuous presence of water for 2 to 3 billion years, which is enough time for life to have arisen there whereas opposed to Mars, as far as I understand, it really only had– climate models only showed episodic times of water. That being said, yes, the odds are is that there is a better chance for existing life in the clouds of Venus because the conditions are still right there for some forms of extreme life, though we know some examples here on Earth.

CHRISTIE TAYLOR: We have to take a break now, but when we come back, the planetary smack talk continues with our guests, Briony Horgan, associate professor of planetary science at Purdue University, and Jaime Cordova, a PhD student at the University of Wisconsin-Madison in genetics and a solar system ambassador for NASA’s Jet Propulsion Laboratory in Pasadena, California.

KATIE FEATHER: This is Science Friday. I’m Katie Feather.

CHRISTIE TAYLOR: And I’m Christie Taylor, continuing our debate over which planet has the best chances of turning up life, Mars or Venus. And joining me on team Venus is Jaime Cordova. He is a PhD student at the University of Wisconsin-Madison in genetics and a solar system ambassador for NASA’s Jet Propulsion Laboratory in Pasadena, California.

KATIE FEATHER: And joining me on team Mars is Briony Horgan. She’s an associate professor of planetary science at Purdue University. And just to note, this segment is being recorded with a live Zoom audience, where Science Friday listeners can ask their own questions about Mars and Venus and help decide the winner of this debate.

CHRISTIE TAYLOR: OK, so Jaime, we were talking about ancient versus modern life earlier, but let’s say I’m out shopping for planet with living organisms on it. What’s going to be on that list of requirements for life?

JAIME CORDOVA: So you need a source of water, which Venus has some water vapor in the clouds. That was detected in the, I believe, in the ’80s, and because of the sulfuric acid that is in the clouds– the sulfuric acid characteristic of it is that it’s very microscopic, so basically, it’s able to– water attaches to it, which means that there may be some extra water available that we’re not necessarily aware of.

You also need energy, so for example, a primary source of energy here on Earth is the sun, photosynthesis. There is enough energy that reaches the clouds of Venus that’s been calculated to be roughly about the same or if not a little bit more than the photosynthetic energy that reaches the surface of the Earth. And then the last thing that you need would be some certain elements that are really needed by life, so CHNOPS– Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

And some days, you need a little more CHNOPS than others. So you not only do you need CHNOPS, but also there are other elements that are necessary. For example, iron is another element that’s necessary for life. And we know that these six or seven elements are present. They’ve been detected at least once in the clouds of Venus.

We somewhat of other abundance, but their actual bioavailability– so is it actually something that’s available to life? We’re not totally sure yet. But that’s why we need to send more missions to Venus.

KATIE FEATHER: All right, well, Briony we have some work to do in terms of tearing down this argument about Venus, so I need to ask you, do researchers really think that they will actually find life in the clouds of Venus? How promising does this phosphine research look to you? And then also, we have Perseverance coming up, and what kinds of evidence could Perseverance turn up that would, for those who are still team Venus, might tip the scales and make them team Mars?

BRIONY HORGAN: Yeah, well, I’ll say Venus is just– I think it’s so fascinating. I’m definitely team Mars–

KATIE FEATHER: [GASP]

BRIONY HORGAN: –though Venus is really cool. I have to admit, right? And Venus, I like to say, it’s literally shrouded in mystery. So the phosphine detection is, I think, incredibly important because it tells us that there are weird things going on Venus that would be really interesting to find out. Now, is it life, right?

I think there is a recent paper that just came out suggesting it could actually be from volcanoes spitting out crazy gases on Venus. But on Mars, I think it’s important to think about, OK, so we’re postulating this one environment on Venus, the clouds of Venus, but on Mars, man, we have thousands of different unique environments that have persisted over billions of years from 4 billion years ago, all the way until today.

Some of these we’ve actually shown were present and had water present for at least millions of years. The Curiosity Rover has been driving through hundreds and hundreds of meters of stacks of ancient lake muds that were deposited in this long-lived massive lake that was almost 100 miles across. So we do know that there were these persistent environments on Mars that we know could have supported life because we found all those, the CHNOPS, the carbon, hydrogen, oxygen, nitrogen, and phosphorus, and organic materials in those muds.

So Mars, in some way, I think it is– as far as these things go, which looking for life is very risky, but as far as these things go, Mars is a pretty safe bet. We know it has all the ingredients for life and the places where life could have lived. So Perseverance is building on that, so Perseverance is going to actually take these really amazing instruments that we’re going to go look at the rocks at very high resolution and look for signs of these ancient microbes trapped in the rocks.

And so we’re hoping to find things like organic molecules in layers and other kinds of shapes that would tell us that they were laid down by microbes, like, for example, the kind of thing we would love to find as evidence of ancient microbial mats growing on the shores of a lake in Jezero crater where we’re exploring. That would be amazing.

And the kinds of things we see from orbit in Jezero crater where we’re landing, we see evidence of this enormous delta that formed when this lake was present in the crater for a very long time. We see evidence of beach deposits where these microbes could have lived. And so we’re hoping, with Perseverance, we’ll actually be able to see the details that will tell us that, yeah, life might have lived here.

CHRISTIE TAYLOR: We have a listener question that I think is a good one for Jaime. First, we have a question from a listener Xochitl, do we have any species on Earth that could help us understand possible cloud life forms? And then hold that thought because I also want– Andrea Walker had a question that sort of is related to that.

ANDREA WALKER: My question was about the atmosphere of Venus having acid in it. Why is it that it couldn’t be– that couldn’t be the basis of their kind of life as opposed to our kind of life here on Earth that is based on water?

CHRISTIE TAYLOR: So that’s a great question, and I do want to front that with Jaime. You told me that Venus has a negative pH when we’re talking about the acidity of Venus, so this is some serious acid.

JAIME CORDOVA: Yes, yeah, so the sulfuric acid– so there’s a lot of sulfuric acid in the clouds. You’re looking at a pH range of about negative 1.5 to 0.5. Admittedly, when I first started doing this Venus work, I didn’t know that there was a negative– that there was such a thing as a negative pH, so that was a surprise to me.

Now, to answer is Xochitl’s question, if there are terrestrial bacteria that could potentially survive, these are called extremophiles. Extremophiles are bacteria that are able to survive in extreme environments, so for example, you’ve got thermophiles, which like really hot environments.

In fact, some thermophiles, if you take them out of hot environments, they die. You have halophiles, which love a very salty environment. And you also have some that really acidic conditions. You also have some enjoy really basic conditions.

So we definitely know of organisms here on Earth that have that capability. The issue is that, for Venus, you’d have to have something that’s known as a polyextremophile, so that would be a bacteria that’s able to withstand multiple extreme conditions.

Now, there are a couple of candidate organisms that we consider may potentially be a good analog of one, for example– and I’m going to butcher the name– is Acidithiobacillus ferrooxidans. Basically, it’s a very hardy extremophile that can live in low pHs and can also live in high temperatures.

So that’s one example now to answer Andrea’s question, in terms of if there’s so much sulfuric acid, is it possible they could be using that? Yes. So the sulfuric acid, it tells us that there has to be sulfur in there somehow and that there are sulfur species there in the clouds.

We do know that there are some metabolisms here on Earth that some extremophiles use that use sulfur and different sulfur species to produce their energy. So I mentioned earlier photosynthesis is one way of producing energy. There’s also something that’s called chemosynthesis, which is, essentially, not necessarily using light but using different chemical elements to gain their energy. And this is something we see in the hydrothermal vents at the bottom of the ocean because no sunlight reaches them.

KATIE FEATHER: I still feel that signs of ancient life on Mars are pretty fascinating and do qualify as good evidence and a reason why we want to be in Mars. But let’s just say, for the sake of argument, that we are talking about signs of modern life. There is something that Mars has that’s equivalent to phosphine on Venus, and one of our watchers– our listeners right now, David Rossiter, has a question about that.

DAVID ROSSITER: Hey, everybody. Yeah, we’ve, for several years now, had evidence of methane on Mars, and I understand that that also could be an indication of life as well as a geological cause as well. Can you all comment on that, please?

KATIE FEATHER: And I’m going to throw that one to Briony first because she’s our Mars teammate. So Briony, what about this methane on Mars? Could that be also a sign of modern life on Mars?

BRIONY HORGAN: Yeah, it could. The reason why it’s exciting to detect methane on Mars is because it’s not stable in the Martian atmosphere over long time periods. Radiation and things will actually break it down, and it’s not stable over scales. We think of like 10,000 years.

So the fact that we see methane today means it’s being produced by something. And so the big question is, what is that something? It could be interactions between water at relatively high temperatures and rocks underground producing the methane, or it could actually be life, living, probably as well, underground. And either way, that tells us that there’s a potential habitable environment underground in the crust of Mars, and that’s another place we’ve thought about looking for modern life on Mars, not just in these salty waters at the surface but also in these probably cozy warm environments underground. And so the methane might be telling us about those deeper environments on Mars. Well

KATIE FEATHER: Christie, I know that we’re going to go to the question about how do we investigate these two planets next, and I think this is where Venus is rather weak and Mars is pretty strong in this case. So we have yet another listener, Vladimir Pittman, who has a question about that.

VLADIMIR PITTMAN: Hello, thank you. About investigating Mars, I was just wondering, like you said, the capability of sending a probe there, that would last long enough to provide samples or if we’d be able to return with samples or it would be something that just collects evidence from the cloud. Do we have the capability to actually get to the surface and keep a probe there long enough to collect samples?

CHRISTIE TAYLOR: Sorry, so you meant Venus–

VLADIMIR PITTMAN: Venus.

CHRISTIE TAYLOR: –correct?

VLADIMIR PITTMAN: Yes, Venus.

CHRISTIE TAYLOR: Yeah, and Jaime, I know– I have this theory in my head like, we can maybe at least like send a big ladle past the clouds of Venus or something like that to like scoop up that cloud stuff, as they say. But I think you had a better vision for how this would actually work.

JAIME CORDOVA: Yeah, so I’m going to backtrack real quick and say that there actually has been methane that’s been detected at least once on Venus. Whether it’s a sure result, we’re not totally sure, but there has been methane that’s been detected in the clouds of Venus. I’m just going to throw that out there.

But to answer the question, yes, so we can investigate Venus in the sense that, basically, it’s– I believe it’s called hot tech, if I’m remembering correctly, but basically, what it is it’s this technology that’s able to– or new batteries, new systems that are able to last for a lot longer.

Now, and that’s for the surface. In terms of the clouds, what would be really cool is if we have balloons, for example, or air robots, which is like a drone in a sense. There are some proposals for doing this. In fact, the Russians already did that with the Vega balloons in the, I believe, in the ’80s.

So this is known to be done. That would be ideal, at least in the sense of habitability. Or coming from a habitability standpoint, I’ll leave the geologists to want to do the surface. But it’s so important to understand the geology because that tells us a little bit about the ancient climate of Venus. But at least for the atmosphere, it’d be cool if we can collect samples from the– aerosol samples from the clouds and not only do that once but also do it on a very temporal and spatial resolution, so at different latitudes and different times of the Venusian day. So that would be ideal, and yes, we can do that.

KATIE FEATHER: Just as a reminder, this is Science Friday. I’m Katie Feather.

CHRISTIE TAYLOR: And I’m Christie Taylor.

KATIE FEATHER: Talking to Planetary Smackdown specialists Jaime Cordova and Briony Horgan about which planet is best to look for life.

CHRISTIE TAYLOR: All right, I feel like I’ve heard enough, Katie. What about you?

KATIE FEATHER: Yes, but I want to make some final arguments in favor of Mars. In one case, we definitely have ancient life on Mars. In another case, we could have even modern life on Mars. We’ve been investigating Mars for longer, and we know how to get there pretty easily. We’ve sent a lot of things there to investigate. We could even send humans there possibly in the future. And we have Perseverance on the way.

So in terms of when you measure the potential evidence that we might find with– and I very heavily weigh this– the feasibility of all of this, of getting there and looking for this life on Mars, i think Mars should be the winner in this case. I rest my case.

CHRISTIE TAYLOR: Well, I wasn’t prepared to summarize my thoughts, So. I’m just going to tell you what I like about Venus, which is that it’s been neglected. NASA actually even has drafted what a mission to Venus could look like. They just didn’t go forward from the proof of concept. So the research is already out there, and we just need to stop doing this whole sunk-cost fallacy situation and get excited about something that could really redefine how we understand life to be. And I think, Jaime, you would make the point that we don’t even understand like 1% of the bacterial life on Earth.

JAIME CORDOVA: We don’t understand 99– or at least some estimates say that we don’t understand 99% of bacteria on Earth. So just because we haven’t found something that is absolutely exactly like something that can live in the clouds of Venus doesn’t necessarily mean that we– doesn’t mean that it doesn’t exist.

KATIE FEATHER: All right, and Briony, I’ll give you the last word for team Mars. Finish strong.

BRIONY HORGAN: Well, I got to say, Mars– so we’re really excited about not just understanding whether or not there was life on Mars but what can that tell us about the origin evolution of life on Earth, too. And I think that is so incredibly powerful, to be able to study a planet where you can not just understand is there life there today or was it in the past but how does it relate back to how we came to be, which I think is really, really cool.

CHRISTIE TAYLOR: I think we have had some really great arguments on both sides, and we did pitch this as something where our listeners get to decide who the winner is. So hopefully, everyone can see the poll that is up on their screen right now. Again, this is a you-decide situation. You heard the arguments from both sides. You had a chance to ask some questions. There is a representative from NASA in a trench coat in this audience. So now is the time to vote.

KATIE FEATHER: And don’t just listen to Christie’s sympathy plea for Venus, how it’s the underdog planet. Think about all the time that we’ve invested in Mars. We should just stick with our current girlfriend instead of looking behind us the girl that’s passing us on the street.

CHRISTIE TAYLOR: My last point to that Katie is that you know that in that meme the wrong girl is wearing the red dress, and what is the red planet? It is Mars. So if we’re going to go with meme language here, I finally have a good rebuttal for that.

KATIE FEATHER: OK, the voting is done, and our SciFri colleague Diana is here to announce the results.

DIANA: And the winner of the poll is–

[DRUM ROLL]

Mars!

[CHEERING]

BRIONY HORGAN: Congratulations, team Mars.

KATIE FEATHER: Team Mars!

CHRISTIE TAYLOR: Well, thanks, everyone, for listening so closely. Jaime, I’m going to ask you to say something nice about the other team since you are the polite loser in this situation.

JAIME CORDOVA: Yeah, all right. It’s OK. Unfortunately, Venus is used to being ignored. But I will say that regardless of Venus didn’t win, Mars is still a really cool as for astrobiology target. Venus is a really awesome astrobiology target that I think we should investigate further. But I think, really, in understanding any sort of planetary body is really useful for astrobiology.

KATIE FEATHER: And Briony, can you believe we did it? We pulled Mars to the finish line. We got it, got a winner on our hands. But what would you like to say about Venus?

BRIONY HORGAN: Well, I really am a Venus fan. I think Venus is a fascinating planet, and I really hope we get to send new missions there to try to understand what it used to be. Venus, we really have no idea what its history was. It could have been totally earthlike a few billion years ago, and what happened?

Something really dramatic happened to Venus to change it, and what does that mean for the history in play? And so I am extremely excited for what I hope are all the new missions NASA will send to Venus in the next decade.

KATIE FEATHER: Thanks so much to our planetary experts for playing with us today.

JAIME CORDOVA: Thanks for having me.

BRIONY HORGAN: Thanks for having me. This was great.

KATIE FEATHER: Briony Horgan is an associate professor of planetary science at Purdue University.

CHRISTIE TAYLOR: And Jaime Cordova is a PhD student at the University of Wisconsin-Madison studying genetics and a solar system ambassador for NASA’s Jet Propulsion Laboratory in Pasadena, California.

KATIE FEATHER: For Science Friday, I’m Katie Feather.

CHRISTIE TAYLOR: And I’m Christie Taylor.

IRA FLATOW: Thanks, Katie and Christie, and you can watch the entire video of this Smackdown and sign up to find out about sitting in on a future Zoom interview on our website at sciencefriday.com/events.

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About Katie Feather

Katie Feather is a former SciFri producer and the proud mother of two cats, Charleigh and Sadie.

About Christie Taylor

Christie Taylor is a producer for Science Friday. Her day involves diligent research, too many phone calls for an introvert, and asking scientists if they have any audio of that narwhal heartbeat.

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