Science Friday - What Martian Geology Can Teach Us About Earth

Episode Date: May 8, 2024

At first glance, Mars might seem rather different from our own planet. Mars is dry, with little atmosphere, and no liquid water on its surface. It is half the size of Earth, lacks a planetary magnetic field, and does not appear to have active plate tectonics or volcanic activity. In some ways it is a world frozen in time, affected only by the force of wind and the occasional meteorite impact.That static nature, however, could give scientists clues to conditions that once existed on Earth, but have been lost to the effects of plate tectonics and weathering. Ira talks with planetary geologist Dr. Valerie Payré of the University of Iowa about her research into the geology of Mars, and what it could tell scientists about early Earth.Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

What can Mars rocks teach us about life on Earth? It was kind of a real surprise, but it looks like Earth and Mars are pretty similar in a lot of way in terms of the geology. It's Wednesday, May 8th, and you're listening to Science Friday. I'm SciFri producer Charles Bergquist. The dry, dusty plains of Mars might not look a lot like home. But by studying Martian geology, scientists are hoping to learn something about the early days of our own planet, from plate tectonics to how the crust formed. Here's Ira Flato.

Dr. Valerie Pai-Ray is an assistant professor of Earth and Environmental Sciences at the University of Iowa in Iowa City, and she studies the geologic history of Mars and other planets with the aim of better understanding our own. Welcome to the program, Dr. Pai-Rae. Thank you very much for having me. It's nice to have you. You know, given the stark nature of the Martian landscape versus the black fertile ground in Iowa, I wouldn't think that they would be connected somehow. For example, if you look at pictures of Mars sent back by the rovers,

you see lots of red rocks. What are they geologically? Is there something on Earth that's like them? Obviously, you must be able to connect the dots here, or the rocks here. Yes, that's a great question. Rocks on Mars are pretty similar, actually, to what we find on Earth. And we thought that Mars rocks were mainly basalts, looking like rocks that we found in Hawaii, for example.

So kind of lava flows all over Mars. And with the recent missions from the Curiosity rover that is still operating at the surface of Mars today, we found more diverse volcanic rocks, including rocks that looks like what are making the continents on Earth. So it was kind of a real surprise, but it looks like Earth and Mars are pretty similar in a lot of way in terms of the geology.

Well, when you say similar to the ways they're making the continents as here on Earth, I mean, we have plate tectonics here on Earth, right? Did they have that on Mars? Well, it doesn't seem like it. We haven't found any proof of plate tectonics on Mars. We don't see like mountains or big basins that are pretty long on Mars. So it seems like plate tectonics didn't really happen on Mars. But we do find those interesting rocks.

that in composition, their chemistry looks like the chemistry of terrestrial continents. So it raised question of like how they formed. And that's a question that I'm working on. Like it could be plate tectonics, but we don't see any proof of it on Mars. So it could be all the processes. And that's what I'm trying to understand. Right. Because we have here on Earth, we have lots of volcanoes. Yes, we do. That bring up a lot of lava rock. Does that happen on Mars? It happened in the past, yes. Mars is covered. of volcanic lava flows, and there were also explosive eruptions, like what happened with the mounts and hailstons, for example, on Earth. So we do see a lot of traces of volcanic eruptions

on Mars, but it seems like it happened a long time ago when it stopped, and today we don't have any evidence of volcanic activities. Let's talk about Mars and Earth in many different ways, for example, how similar are they? What about size, land mass, things like that? Gravity. Yes, so Mars is twice smaller than the Earth. In terms of the gravity, its gravity is also lower because of its smaller size. The atmosphere is way lower than on Earth.

It's a really thin atmosphere. So even if there is wind on Mars, it would not blow away like rockets or robbers. it's not really possible. So it's kind of different than what we have on Earth. But otherwise, we don't have any magnetic field on Mars as we have on Earth. So Mars seems like this planet that died a long time ago, but there are still some wind activity happening. But it's definitely not really active anymore like Earth.

Why doesn't Mars have a magnetic field like we do? So it's related to the core. So on Earth, we have the magnetic field because the core is having some liquid moving, and that is creating this magnetic field around the Earth. And on Mars, because it's a way smaller planets, it cooled down way faster than on Earth. And so we think that the core on Mars is not really convecting anymore. It's not liquid anymore. And so that would prevent any magnetic field happening anymore.

So it was there a long time ago, but it was shut down after less than a billion years after the formation of the planet. That's interesting. It almost sounds like these things are somehow connected. The lack of plate tectonics, the lack of active volcanoes, the lack of a magnetic field. Are they linked somehow? Yeah, kind of. Somehow it's all linked to the temperature inside Mars, right? So you would have plate tectonics because you have.

have some movement inside the mantle that make plate tectonics happening. You have in the core some movement of liquid thanks to the heat. And on Mars, it's, again, it's a smaller planet. So everything cooled down quite rapidly. And even though it's still hot, it's not all cooled down today, but it's not hot enough to make liquid movement inside Mars. So that would prevent any volcanic eruption, any plate tectonics. and the magnetic field just shut down.

So, yeah, everything is kind of related. Was there once an atmosphere that is now gone? Yeah, well, actually, there was, yes. So we think in the first billion years after the formation of Mars, there was a thick atmosphere, possibly like Earth today, but it was lost to space because of, again, the lack of magnetic field. So it's kind of also related to the small size of Mars. and the cool temperature inside.

And so all the atmosphere was ripped out by the solar wind. And now we don't have this thick atmosphere anymore. And now it's some wind happening, but there is no water or liquid water at the surface of Mars today. And that's also related to the lack of a thick atmosphere that could maintain that. That is really interesting. And if you don't have plate tectonics, how does that affect? the geology of what's going on in the history of the planet and what's going on now?

It can affect a lot of things. We see on Earth, plate tectonics is it create all the mountains we're seeing. So it's really a cycle of a lot of elements, a cycle of water, cycle of carbon dioxide, cycle of sulfur. So there is a lot of cycle going on on Earth that make life possible. And that is also thanks to play tectonics that's enabling this recycling happening. So the lack of this on Mars would definitely limit at least life on Mars in the past. So we don't have any evidence of life beginning on Mars, even though we're looking for something telling us that maybe it happened a long time ago. But if it started there, it would have been shut down very rapidly because there's no recycling. of all of these really important elements, including water. Without Pleatectonics, life is hard to

maintain on a planet. So if we want to see if there are any alien out there, Playtectonic could be a good place to start. I never heard that as a good clue. Explain that a little bit more in detail. So it's not really my field here, but it's just that plate tectonics enable the water to be emitted to the atmosphere and then going back into the interior of the earth. And you have the cycle of water being going out and going inside the interior. And that enable hot temperatures and environment favorable for life. And so with even the thing that maybe life on earth started along those midosan ridges, which is where the crust on earth is being formed.

And that's directly related to plate tectonic. So it could definitely be a clue. Maybe it's not the only environment, but it could be a clue. What fascinates you most about Mars geology? What are you trying to learn from it? So from Mars, I'm trying to understand what the surface and the interiors are made of and how it is similar to Earth. We know that Mars a long time ago might have looked like way more Earth today.

and a lot of things happen, including shutdown of the magnetic field that affected the atmosphere and then no water anymore at the surface and no volcanic activities. So we kind of make the planet dying out. But I'm really interested in Mars a long time ago after its formation, what it looked like. And if there were any processes that would tell us that maybe plateactonic started there or what processes could explain the diversity of volcanic rocks we're observing on Mars. My goal is kind of to better understand the Earth because we don't know what the Earth look like after its formation. We don't know how the crest was formed.

We don't know exactly the first stages of plate tectonics on Earth. We have ideas and a lot of debates going on, but we don't really know because we lost a lot of information because of plateactonics, actually. So Mars is sort of like a planet that stopped. Yes, it stopped in terms of the interior and surface activities. Now it's mostly the wind and some impacts happening at the surface. So it's not all died, but it's still, yeah, the interior has been fed off for sure. You mentioned different kinds of rocks on Mars.

There are sometimes, we all know, on Earth, veins of concentrated metals like gold or iron or copper? Do we know if there are mineral deposits like that on Mars? Well, actually, that's a topic I was working on during my PhD, so you're pouring that out right there. Well, did you find any? So with a curiosity rover, so it landed on Mars in 2012, and it has been traveling in this impact crater. And it was this crater, long time ago, was filled with water. So it was a lake. And what we found is those rocks that contain a huge amount of copper, actually, which is not supposed to happen. Like that elevated amount of copper in there is not supposed to happen without processes that we know are occurring on Earth, like hot temperature

fluid circulating through rocks or things like that. So finding those copper-rich rocks on Mars is definitely telling us that there are processes that we thought did not happen on Mars, but actually did. And it's very similar to what we see on Earth today. So another evidence of it. So you used to think that Mars is sort of like Hawaii, where you had all this bubbling volcanic, frothing rock until you started finding all these great minerals there and saying, hey, there's something else going on here. Exactly. Yeah. And that's some discoveries we did with the Curiosity rover, mainly. And so it was like 10 years ago on me. So up to 10 years ago, we thought it was just basalts in Hawaii all over, but it's not at all. It really looks like a lot. There are some

processes that are hidden and that looks like what we have on Earth. So it's really exciting for the future. That is exciting. I mean, there's been a lot of talk about a Mars sample return mission. Yes. Which it looks like now may maybe delayed a bit. How much would you have to sample? of actual Mars rock to satisfy you and change how you look at Mars or change your work? Could we sample all over Mars? Well, I don't know. Would you like to go there yourself and sample it? That's too dangerous for me.

But we need more rocks for sure. So with rubbers, we can do a lot of analyzes over there on the ground. The problem is we cannot do any sample preparation. We cannot do what we do in our labs on Earth because it's just a robot, right? And so the idea is to have these samples back from Mars to Earth. And that would be really fantastic. And to understand, to me, my main question is related to the crust on Mars and the first processes that formed it and how it evolved in the first billion years

after the formation of Mars. And so to understand that, I would need some volcanic rocks that are extremely old, that are of different compositions, so basaltic, but not only, more like composition matching continent on Earth. So I would need a lot, but with maybe three, four samples, that would be sufficient. The problem is we haven't found those composition that are matching continent on Earth yet with the rover. So we'll see. We have a helicopter on Mars, right? It couldn't that go out, pick up some samples and bring it back?

I mean, theoretically? Well, so right now, the helicopter that was with the Perseverance rover for the Mars return mission, it's not working anymore. It did its work and it's fantastic as we know that we can fly on Mars, but we cannot use it anymore to fly around and it could do just images. So it could not grab a rock and put it close to the rover or a sense. it back to Earth. That was not the plan. So what NASA wants to do is having this mission going to Mars and lending a platform where the Perseverance rover would deliver all the samples. And if the

perseverance rover is not working anymore, NASA is having this helicopter that would get the samples back to the platform. Back in the 1970s, we sent a probe that landed on Mars, the Viking. I remember going to JPL and watching first photos coming from the surface of Mars. And it had a little chemistry set on board to sample the soil, but it found no hard evidence of life. It's a little bit controversial to this day about the results. But what do you think? Could we or should we do the same mission all over again with a better chemistry set? That would be ideal. But still, I don't think even today with way more technologies and advanced instruments,

I don't think we could tell right away if life is in the sample because we need to do really advanced and complicated measurements that necessitate a lot of sample preparation. And the sample preparation, a rover, cannot do that. So that's where the Mars sample return mission is really important.

We want to send samples back to Earth to actually do those complicated analysis in our lab on Earth. where we can do anything we want and do the sample preparation that is required. Well, one last question about Mars, and it has nothing to do with Mars. And that is, what about other planets? Other planets of interest to you in our solar system? Any other ones?

What do you say? Yeah, I'm really interested in Venus, too. So this planet is kind of the opposite of Mars. It's really hot at the surface. The atmosphere is really thick, way thicker than on Earth. Earth. The size of Venus is similar to the size of Earth. And I really want to know what Venus is at the surface in the interior. We have no clue of it. So we have several missions, NASA and the European Space Agency sending missions there this next decade to have actual data from there. And that's

really exciting and I look forward to it. Wow, that is exciting because we can't really see the surface much beyond what radar shows us, right? That would be interesting. Yeah, definitely. And we know there were volcanic activities in the 90s, so it seems to be still active. So that's really exciting. Okay.

I'm signed up for, well, not going, but talking to you when we go there and come back. Look forward to it. Thank you. Dr. Valerie Pirae is an assistant professor of Earth and environmental sciences at the University of Iowa in Iowa City. Thank you for taking time to be with us today. Thank you very much for having me.

And that's all the time we have for now. a lot of folks helped make the show happen this week, including Beth Ramie, Santiago Flores, Diana Plasker, John Dancosky, Robin Casmer, and many more. Tomorrow, one of the nation's biggest name athletes right now is Iowa's Caitlin Clark. We'll talk about how research into women's athletics is still behind the curve. But for now, I'm SciFry producer Charles Burgquist. Thanks for listening. We'll see you soon.