 one o'clock on Tuesday, March 29th. So you must be watching Science at Soast. I'm your host, Pete McGinnis-Mark. And every week we introduce a graduate student or postdoc, a young scientist, describing their research and how it's relevant to the state of Hawaii or general education. So today we have Gwen Bauer who is a graduate student in the Earth Sciences Department. And our topic today is going to be Saturn's moon time. And I'm really excited about that because back about 20 years ago, I was interested in an early mission to Saturn. And that was called Cassini. And I'm hoping that Gwen can give us some updates on some of the research that she's been doing. So Gwen, welcome. It's a pleasure to have you here on Science at Soast. And this is an exciting topic. And I understand you're a third-year graduate student. So this must be a really good educational experience for you. Yeah, yeah. Thanks for having me. I'm excited to talk about Titan. And I guess we should explain to some of the viewers where Titan is in the solar system because in previous episodes of this series, we've been looking at the Earth and maybe once or twice at the moon. But I believe Titan is a moon of Saturn. And I think our first slide will give us sort of an introduction. Saturn is one of the few objects we can see from Earth with our telescopes. But obviously, this is a much better spacecraft view. How did you get interested in studying either the Saturnian system or these outer worlds in general? Well, so I have always just kind of been interested in icy satellites. So that's what we call the icy moons of the gas giants. I did a project in undergrad where I was modeling impact dynamics. And one of my focuses was just kind of figuring out what would happen if a big object hit an icy body. And so that kind of led me to Enceladus. And maybe, I don't know if people know about Enceladus, but Enceladus is one of Saturn's moons also, as well as Titan. And it has these fractures in the South Pole that spew vapors, mostly water. And so I just thought that was really exciting that there's these bodies out there that are mostly made of water and ice. Why did you do your undergraduate work? Or why did you come to Manoa? I came to Manoa because I found Sarah, who was working on this project studying the dynamics of Titan's ice shell. And I thought that would be perfect. This is Dr. Sara Fajens, right? Yes, Sara Fajens. Yes, OK. All right. And so you said you studied in Enceladus which is an icy moon of Saturn. I think to put more in context, let's take a look at the second slide so that we've got some understanding of how big some of these satellites might be. And we're focused today on Titan. And here's a great comparison between the Earth, Titan, and the moon, right? Obviously, they're further apart than this slide would make out. But Titan looks as if it's a world in its own right. Would that be a reasonable assumption? Well, I mean, Titan's huge. I think it's bigger than Mercury even. And it's got just so much more water than you see on the Earth. Really? So if you were to measure the volume of water in the Earth's oceans, Titan has more water. Is that because there's less rock in the interior? Or why do you make that statement? Well, I don't know. It necessarily is because there's less rock in the interior. But at the beginning of the solar system when all the planets formed, if you were a certain distance from the sun, you as in imagine you're a little baby planet or baby satellite, you could accumulate more volatile materials. Water being one of the main ones because you're further from the sun, so you're not going to vaporize. You can accumulate as ice. OK. And Titan being out as far as Saturn is from the sun, it must be much colder there. It looks as if it's got a variety of surface features. Maybe our third slide will show us some of the early views on Titan with an artist sketch in the background. But how have we discovered different aspects of the geology and atmospheric chemistry of Titan? Here are four different images. Can you just walk us through what we're seeing here? So the first few images, you'll notice that it's just kind of a yellow blob. And it's tricky to look at Titan because it's got such a thick atmosphere. The surface pressure is one and a half times that of Earth's. And Earth has a super dense atmosphere as it is. So these images kind of just show the atmosphere blocking our view of any of the geology going on on the surface here. The, I guess, last image here, we can see some more features because we're looking at it in a different wavelength. So the first three are going to be visual images. And then this last one is in the near infrared. So we can see more of what's going on down on the surface. And it's interesting that the top left image was dated 1979. And it just looked like a fuzzy orange ball in those images. And it really hasn't improved until 2004 when you've got these different ways of the infrared data. But Titan is a really interesting planetary object. And so I think the fourth slide will let us show the viewers a little more of how Titan is different from the Earth. And here's the absolute. Talk to us a bit about the atmosphere of Titan and how it differs from that of the Earth. Well, I mean, the fact that it's mostly nitrogen doesn't make it that different from the Earth's atmosphere. I think the Earth's atmosphere is roughly 80% nitrogen. I don't know. Do you know, Pete? Something around there. 81. And it's got like, huh? Yes, 81. So close. And then it also has a little bit of methane. It also has a lot of different hydrocarbon materials that actually fall to the surface as rain, which is another similarity with Earth. But it's very cold. So this rain isn't going to be liquid water, right? It's liquid hydrocarbons, which is really exciting. And I know we have a slide in here on the lakes. And the atmosphere pressures about one and a half times that of the Earth. So we had a question come in on the chat show. Is it possible that humans could actually live on the surface of time? What would be your feeling on that? Um, a bit chilly. A bit chilly, yeah. And of course, you couldn't breathe the atmosphere. Doesn't appear as if there's any oxygen, right? Hardly any at all. Hardly any at all. So that would be quite a challenge. And the temperature nearly minus 180 centigrade, I guess that's what, minus 290 minus 300 found height. It is really cold. Do you know what water would be like if it was on the surface of Titan? At that temperature, it must be presumably ice, but much colder than even the ice in Antarctica. Right, right. Well, the last image, we saw that some images were collected back in 2004, and I think that was from the Cassini mission. The next slide should show that Titan actually has quite a variety of landscapes. And is this a computer-generated image, the one we're looking at right now, that there seems to be lakes and orange line? Is that for real, or is that a computer-generated version? Well, a little bit of both, I guess. It's, this image is based off of radar images of the surface from Cassini. From radar images, we know that these liquids, they appear smoother, and they also appear radar dark. So, yeah. So we can then interpret what these features are, and they assign these colors to it. So this isn't a visual image. You're not actually seeing blue, liquid, methane, and ethane lakes, but those are lakes in those areas. And I'm told that the largest lake, the Krakamae, is actually bigger than the Great Lakes in North America. So these are fairly large puddles of liquid. Yeah, these are huge. We call the bigger ones seas, for that reason. OK. All right, and the radar lets us see the surface, these earlier images that we saw, Titan just appeared to be a fuzzy ball, but the radar has a long enough wavelength to see down to the surface. Yeah, so the radar can see through the atmosphere because it just, it bounces off solid surfaces. And so we can get information from that, avoiding the whole atmosphere problem. And yet, we have to assume that the atmosphere, just like Earth's atmosphere, must be changing the surface over geologic time. Because these are old surfaces, right? They're probably older than North American continent, would be my guess. Have we seen any closer levels of detail that this is, that was a radar image of roughly the North Polar region of Titan. What's it like in detail? I understand there was a European spacecraft which actually landed on Titan in 2004, right? Yeah, so the Huygens probe, it took a lot of measurements of the atmosphere mostly because they weren't really sure if it was going to make it upon landing. But it landed in, I think it was one of the more equatorial regions, just based on these images here, it looks a lot drier. And as it landed on the surface, you can see these like mountain ranges. And actually on the surface, there's evidence of like rounded rocks. And so rounded rocks are typically associated with like fluvial processes because they've been eroded or Aeolian. And so that just tells us that there's an active weather process happening on Titan or there was in the past. And let's take a closer look at those three images that the Huygens probe took. Not on the ground, but during its descent through the atmosphere. It looks as if, you know, there's a shoreline in the top left image and that sort of dendritic pattern in the top right looks very much like streams or river valleys. Would that be an incorrect interpretation? Ooh, I think that's a correct interpretation. In these regions though, it is dry now, but these are most likely leftovers from when it was wetter around this area. Okay. Does that mean that the climate has changed or that you've got some annual variation in when it rains for want of a better term? Yeah, I think so. And I don't know the time scales that it happens on, but like one interesting thing about Tainas is most of the lakes and seas are present in the North Pole and in the South Pole, there's evidence of previous lakes and seas, but they're all dried up. So this tells us something is changing with time. And there didn't appear to be many big craters in that radar image. Craters, of course, is a proxy for telling how old the landscape is. If there are many big craters, it's presumably in the older area. If there are few craters, then it's quite young. So this North Polar region of Tainan is quite young, geologically speaking. It's, yeah, it's very young. And all of Tainan too, there's not a lot of evidence of craters. And it's similar to Earth in that respect too. It's got this like active weather that's eroding potential craters. So you really need to be a meteorologist as well as a geologist to study Tainan. And I think some of your actual research that you're conducting, that involves both the meteorology and some of the interpretations of the landscapes. Maybe the next slide will show what the atmosphere on Tainan is. And I believe this is just a schematic. We're looking at things where particles are falling out of the atmosphere. They're not that big, right? Yeah. So explain this. So this is kind of, as I understand it, the research that you're doing. What are you trying to model here? So we're actually looking at these special types of lakes in the North Pole that are different than like the seas and these like more irregular shaped lakes. Part of the reason that Tainan's kind of exciting is there's so much methane in the atmosphere. And based on the fact that there's photochemical reactions happening in the atmosphere that's destroying methane in order for this methane to be sustained, like something needs to be replenishing it. And so that one of the ways this could happen is something called cryovolcanism, which is essentially volcanism, but with like water and other volatiles involved. And so we're looking at these special types of lakes and thinking those kind of look like explosions. Is that a way for methane to get delivered back to the atmosphere, maybe? All right, and your next slide, slide eight, I think shows some of these unusual looking features, right? And here again, I think at bottom left, we're seeing the North Polar Region image again. And what are A, B, C and D? How do you interpret this image? So, yeah, we're looking, that little red box, that's where we're looking. It's just this one area of the North Pole. A, B, C and D are four examples of these weird lakes I'm talking about. They are unusual in the sense that they have this circular crater and some of them even have, if you look at, I guess A, B and C all have it, there's like this inset crater. That implies maybe like collapse. The radar bright, as in the white circular area around these craters, we think could potentially be like ramparts of ejecta. We do think these ramparts are raised, which is strange. You don't expect to see a lake that is elevated. So D is one of the drier ones. So you can see A and B, those dark regions in the middle, that is interpreted to be like liquids, a wetter area, as well as the areas around the radar bright halo. First, clients, could they not be meteorite impact craters or do you see the same kind of landscapes which are non-serve tumor? Well, so the reason, well, one of the main reasons we don't think they're impact craters is because of this inner ring that shows up in a lot of them. That's just not, you get more of a bowl shape when there's an impact. And it's also unusual that they're in one of the youngest regions on Titan. Okay, all right. And are there any similarities of Titan with its atmosphere and what appears to be a hydrologic cycle? Do you see something comparable to this on Earth? What kinds of analogs might exist? So one of the proposed formation mechanisms for these features is like volcanic mar explosions or like vapor explosions when hot magma comes into contact with water underground. It usually forms these craters with like raised ram parts of ejecta. Yes. And recently though, these features that's shown on screen here now, they're called gas emission craters and they've been showing up on the seafloor and in the Siberia and Yamal Peninsula. They are pretty much gas explosions that create these massive craters and these raised ram parts. And so we've drawn a connection between these features and raised ram depressions or the pits, weird lakes I've been talking about on Titan because of the connection with the morphology and the potential contribution of methane clathrates. So Titan is thought to have a lot of these things called methane clathrates. They're essentially like a gas molecule trapped in an ice cage. And so if the pressure or the temperature changes it can really cis gas. And on earth, we know that there's a bunch of methane clathrates under the permafrost and as the earth is warming or the pressure is changing, they can release gas too. And so that's one of the mechanisms that's thought to form these features on earth is the accumulation of this methane that's been released from clathrates under the permafrost and exploding. So there's kind of a couple of connections there. And one could ask why does anybody study something so far out in the solar system? But is there a connection here if you're studying these pits on Titan might that lead us to better understand these explosion craters in Siberia, for example, or are you seeing- Well, yeah, so sorry, can you repeat that? I was talking- Are you seeing any differences between the pits on Titan and the really good analog that you had from Siberia? Yeah. Well, so the Siberia craters, they're a lot smaller. If you remember that image that there was about 20 meters diameter across, most of these features we're looking at on Titan are, oh, somewhere between, I wanna say, two and eight kilometers in diameter across, so much larger. As well as the distance the, well, the bright halo is what we interpret as the ejecta. So as well as how far that is from the crater is a lot more than the ones on earth. But we are trying to model this gas explosion process for the craters on earth so that we have this higher resolution data set to test this slow gas accumulation and explosion model on Titan. And any guesses on whether the lower gravity on Titan or the thicker atmosphere or the colder temperatures might explain why the pits are bigger on Titan than on earth? You know, that was, I guess, one of my initial hypotheses, like the lower gravity would maybe contribute to the fact that these features are bigger. But we found that because of the super dense atmosphere the lower gravity of Titan, which is about the acceleration of gravity on Titan is like 1.3 meter per second squared versus earth 9.8. The gravity and the atmospheric drag kind of balance each other out. So it's really interesting, like these objects that are the same size with the same initial conditions go almost the exact same distance for Titan and earth. Okay, and you're trying to generate gas to cause the explosions. Is the boiling point of methane at the right sort of temperature? Because if Titan's really cold, presumably you've got to get to the point where you go from solid to gas or something like that. I mean, it must be a fascinating combination of topics where you're trading off gravity and atmospheric pressure and temperature and composition as well. Yeah, there's a lot of different things that go into it, but I think that's what kind of makes it exciting, but we're not really modeling the vaporization of methane, just the release of methane from clathrates. So the temperature needs and the pressure needs to be at the point where the ice can release the gas. And so this can be done if we raise the temperature a little bit, maybe with some thermal plume coming up from the lower ice shell. It just heats up the surrounding ice and can release gas, but these temperatures don't need to get nearly to anything much, much higher than the temperature of the ice shell already. And it sounds like you know something must be injecting new material into the atmosphere, otherwise these hydrocarbons would no longer be present, right? So there must be some explosions or something going on. Well, yeah. So maybe this is one way. Yeah, Titan looks as really interesting. And I think the last slide will sort of give us a glimpse of the future. Obviously as a graduate student, you're thinking about careers later on. I understand that the Dragonfly mission is going to be going back to Titan in a few years time. Yes, I'm very excited for this. Still got a little while, but it should get there in 2034. Yeah, right. Well, you'd be a professor by that time, of course, but is this where you think your career might take you, that you know sort of research on outer planet satellites, is that something that's exciting for you? Yeah, that's the goal. And I would love to be able to work on this mission too. Sometime. So who actually, not only individuals, but which countries are interested in studying Titan? Is it just the U.S. or the Europeans? Or do you know? You know, I'm not exactly sure. I do know that NASA and like John Hopkins, I think it's the APL physics lab, could be wrong, are the ones that are running Dragonfly? But then ESA, the European Space Agency, was a partner during the Cassini mission, particularly with Huygens probe. So maybe there's a potential for that. But yeah, it certainly seems that, you know, the further out in the solar system we go, there are all these fascinating differences between the way the Earth is formed, compared to Titan in this case, you mentioned in Salatus as well. So, and when do you hope to complete your research? I think I have a couple more years left of this program. So hopefully before then. Well, good luck to you, Gwen. Thank you. I'm afraid we've run out of time. Let me just remind the viewers, you have been watching Science at Home at Soast. I've been your host, Pete McGinnis-Mark, and my guest today has been Gwen Brow, who is a graduate student in the Earth Sciences Department. So Gwen, thank you very much for telling us something about this really fascinating object out there in the distant part of the solar system. So thank you again for coming on the show. And for the viewers, we hope to join you again same time next week. So join us then. And for now, goodbye.