Thank you. Good morning, good afternoon, good evening, wherever you are on this planet, and welcome to our SETI Live. Surprise, surprise, I'm not Beth Johnson. She was supposed to be part of the SETI Live, but she's sick, and she has no voice. So she decided that I will be the right person to replace her. And today we are going to talk about Titans.
so welcome to all our viewers thank you for joining us and to talk about this amazing saturnian moon the largest moon of saturn and a place which is very exotic full of rivers seas we're gonna talk about that pounds of methane and other exotics exotic things we have with us uh dr sam birch hi sam how are you hey nice to be here nice meeting you uh you are assistant professor at brown university Yeah. Yeah. That's what you're calling us from. Yeah. Good. Good. All right. So let's start a bit.
Context. Context. Important. We are talking about Titan. So Titan is not very is a very special moon in our solar system. As I mentioned, he has this very interesting surface. We know that into the Cassini mission. He has a very thick atmosphere. He has liquid on the surface. So some you Tell us a bit why you are interested in studying this very special place in our solar system. I think you hinted at it there.
Titan is, I think, the only other place other than Earth that has something to offer everyone as a scientist and even the public. It's the only place where it's raining right now. It's raining liquid methane. It has rivers flowing with that methane down to the coasts. Wind is blowing and kicking up waves on those seas. It's got a global desert across the entire equator. It's got mountains. This thick, thick atmosphere that's raining plastics down to the surface.
And this whole global subsurface water ocean that may or may not be in contact with this organic rich surface. So it kind of has something for everyone. And it's a really, really exciting place where everything looks similar but behaves very, very differently. So it's a playground kind of for us as well. Yeah, it's a playground for geomorphologists, geologists like you. So you mentioned that Titan has those interesting fluvial structures like rivers, yet seas, and so on.
So the point of your paper is basically that it doesn't have something we were expecting to see, which are river deltas. Yep. Yeah. So we kind of noticed it a while ago when I first was looking at Titan. as a graduate, as an undergraduate student. And you see these huge, huge rivers that are like the size of the Mississippi in their width, um, or bigger, right. They're multiple kilometers or miles across.
Um, if you're standing on the edge, you wouldn't be able to see the other side of the river. Right. Um, those size rivers on earth, when they hit the coasts of earth, oceans always have a river Delta. Um, and when we looked at the ones on Titan, only one of them out of like, seventy something of that size had a river delta. So it seems to be the exact opposite. And the point of the paper was, is this real or was Cassini just not able to see the deltas?
And in the paper, we kind of go through this hypothesis carefully and we're like, actually, the deltas really aren't there, which as a geomorphologist is kind of disappointing, right? You want to see this feature and study its shape and what you can learn about the climate. So we kind of have to do the opposite of they should be there, but now they're not. And so the question next is why, why is that?
Okay, so before we answer to why, let me say hi to people who are watching us from this planet Earth. We have people from Sweden, Sal, from Oregon. Welcome. We are talking about Titan, an exotic satellite of Saturn. And the mystery here is that recent analysis showed that despite having rivers, Titan doesn't have any delta. So how did you figure this out? What did you use as an instrument? Because I do remember, I'm going to confess something.
We observed Titan with the Keck telescope and the adaptive optics system for years. And frankly, when you look at specific wavelengths, invisible and infrared, most of the time you don't see anything because Titan has such a thick atmosphere that you don't see the surface. So how did you manage to get observation of the surface and see whether or not there was that delta? So we used data from the Cassini mission. It had a radar.
The instrument was called the Titan Radar Mapper, and it was designed specifically to look and map Titan surface, hence the name. And so out in the radio wavelengths, two centimeters is the wavelength, the atmosphere is completely transparent and the radar can see right through it. Just like Earth, right? That's how we send radio waves out to space. And so we use that data.
The first thing that we wanted to do is like if you have when you look at radar pictures of Earth, water is very absorptive, so it appears very black in the images. This is we use it a lot to look for like flooding and stuff after storms because you can see through the clouds and you can see the water on the surface to like then direct resources for people. On Titan, the methane is super transparent. And so you can see through a hundred meters, kind of no problem.
You can see right to the sea floor. So if you're trying to map a coastal landscape, you don't get that bright land, dark sea contrast that you get on earth. And so we wanted and we tested it on Earth. Like, could we still see the Mississippi River Delta? Could we still see like South Padre Island of Texas? Big, big features. And are they even visible? and kind of what was Cassini sensitive to.
And then we went back to Titan and re-looked at the Cassini data once we kind of figured out what Cassini should and should not see. And the takeaway was it should see the big things and especially if they extend into deeper liquids. And then when we went to Titan and we still saw almost nothing. And so I was like, OK, yeah, they're really not there. So it's always difficult to publish a paper on negative discoveries, basically.
Even though they're extremely important, if you don't see what you expect to see, you probably spend a lot of your time trying to make sure that there was not an issue with the instrument or an issue with the lack of sensitivity or things like that. So that's why you made a comparison with Earth, I'm assuming, correct? Yeah, so we know Earth really well. We know what its landforms look like. We know the processes that are shaping them. Compared to Titan, we know things really well.
And so we know the delta is there, right? And so if we simulate what it would look like to Cassini, and if we can't see it, and then we did that for tons and tons of landscapes all across the coastal U.S. we kind of trained ourselves and showed quantitatively of like, you can't see this, you can't see this. You'd probably miss that one. You'd probably misinterpret that one. But the big stuff you'd still see was kind of the takeaway. All right.
So what does that tell us about Titan and how it works? What can we learn about the erosion? I mean, Delta are formed by erosion, by the type of sediment and stuff like that, right? It's very cool. Yeah. So deltas are basically you take all the sediment eroded and transported off the continents. And when it hits the ocean, you concentrate it into a wedge, a triangle, a delta shape, like the Greek letter. And so they're kind of like this. You stuff everything into one tiny spot, tiny.
And so what it means on Titan, we're still kind of working that one out. It could mean that it doesn't have transportable sediment. It could have these rivers flowing and they could be completely empty of sediment, which would be a mystery of why that would be. It's unlikely because we see the river or we see the dunes all across Titan, right? That's sediment. The one spot we landed on Titan with the Huygens probe, we saw a bunch of river gravel just sitting there.
So if I happened to land anywhere on Earth and I saw that, like a decent assumption that there's some sediment on the landscape that can move. We showed in a separate paper a couple years ago now that sediment is, if it's produced, should reach the coasts because it's more mobile than sediment on Earth relatively. And so that was our first hypothesis is like, hey, maybe the rivers aren't good at transporting sediment. And the answer was no, it's the opposite. They're actually better than Earth.
And then the next one was, hey, maybe we can't see them. And that was like, no, we actually can see them. So there's some students up at MIT that we're working with that are working on other hypotheses that are like, maybe wind and waves can move the sediment. And you kind of smear it away. That would be one. And that happens on Earth all the time. So if you look at the river, oh, god.
Right at the Texas-Mexico border, there's a little river delta and a big barrier island coming off to the north of it. That is a river delta. It just doesn't look like the Mississippi one. So they don't all look the same. And that's because waves and tides can move stuff around once it's there. Um, so that's one hypothesis. Maybe we'll see.
Um, another hypothesis is, uh, if you have the sea level going up and down quickly on Titan, like it does on earth, uh, you're also gonna smear where you put that sediment. So maybe you're just disguising it that way. Um, and then the last hypothesis that's more exotic that we're working on is maybe the rivers when they hit the seas, they just go straight down and rivers on earth are buoyant. So when you, if you go to like the end of a river.
and you see this big plume of stuff coming out, that's because the river is slowing down and it's dumping out all of its sediment. And that's because fresh water is more buoyant than salty water. On Titan, it might be the opposite. And so your river hits the sea and just is like, I don't care that I just hit the sea. I'm going to keep going and do my own thing. So maybe that's where we're at. And we're testing all those with models, some math, some lab experiments, as we'll see.
There's something else that we haven't thought of yet, probably. Yeah, there is probably some other hypothesis that maybe our viewers will come up with some ideas here. By the way, if you have any questions, we're going to take a few questions for our speaker. OK, so you don't have a clear explanation. You have multiple ideas. What can you say? We are the SETI Institute, and we always love thinking about the research done by our colleagues as kind of a way to detect life or to explain life.
I mean, we're focusing on life, astrobiology in general. So what can, what your research can tell us about habitability or sign of life on Titan specifically? I think there's three answers to that. I'll give them quick here. Um, one Titan surface is really, really cold and it doesn't have liquid water. So life in liquid methane would be hard. There is some like theory that it might be possible ish. Um, so it's, it's gonna be difficult at Titan surface. Um, it doesn't mean it's impossible.
And if there's ever a place that it would be, it would be along shorelines where you get big. you got a lot of evaporation precipitation, which creates what are called chemical potentials that life likes to take advantage of. And so on Earth, deltas are full of life. And it's kind of where you mix different fluids. Lots of fun stuff and fun chemistry can happen. So if there is a spot on Titan surface, it would be there still unlikely.
The bigger thing is, I think we can like better understand how rivers and deltas well, deltas and then rivers and coasts interact kind of quantitatively for understanding preservation of stuff. So Mars has lots of deltas. So if we can fundamentally understand how deltas work by going to something totally different, then we can learn something more about these habitable environments on Mars.
and then on Earth right I mean a huge chunk of Earth's population lives on river deltas and these are prone to flooding and with rising sea levels right these are the first things that are are going to be most vulnerable and Titan is a place where we can understand the true fundamentals of how these things are working um and that's kind of what's exciting to me it's like kind of the habitability of our own planet of us if that makes sense it's not so much looking for life on other
planets um if you are going to do it on titan you got to go to the subsurface no um there is delta as well on mars no yeah so most missions we sent to mars have gone most have gone to what they thought were lakes, um, or things that might've been lakes that maybe weren't in the end. Um, and stuff that had river deltas and sediments, uh, Gale Crater has deltas around it. Um, that's where the Curiosity Rover is. Jezero Crater is where the Perseverance Rover is that had a delta.
That's why we went there. Um, deltas are really good at preserving stuff because you've got all this sediment raining out, kind of just keep stuff there and then you lock it in. through time, right? And so that lets you then go read it like a book. So Delft is really exciting for that sense, on top of their whole freshwater, saltwater mixing stuff. All right. So I noticed that you're wearing a t-shirt. Can you show us the t-shirt you're wearing? Oh, yeah. Dragonfly. All right.
So this is not a science fiction movie for people who don't follow. Dragonfly. is the next mission for Titan, right? Can you tell us about Dragonfly and your involvement in the mission? You're not wearing the T-shirt, I'm assuming. Dragonfly, I think, is the most exciting thing NASA has done since Apollo, maybe. It's a one-ton octocopter that's powered by a nuclear reactor. And it's got all these instruments on the inside, ovens and stuff to see what Titan's made out of.
And it's going to go fly around on Titan. So imagine the Curiosity or Perseverance rovers, except it's flying. That's Dragonfly. And it's going to go to Titan where the wind is blowing, dunes are moving, maybe it rains. It's going to be absolutely spectacular. And we're not going to fly once or twice. We're just going to fly once a month, and we're going to keep doing it. So is it going to hop in different area of Titan and do some experiment on the surface and go to other places?
Yep. So it has drills to ingest material into the it's got a bunch of mass spectrometers and inside of it to see what all this stuff is. It's got a seismometer that it can drop down from its belly. It's got all sorts of wind and humidity sensors and cameras. So, yeah, we'll spend time on the surface. And then when we're ready to fly, we'll pick up the whole thing and fly to the next spot. So the temperature and the pressure on Titan, you know the numbers, but on the top of you.
Yeah, it's the pressure is one and a half times the surface pressure on Earth. OK, so it's a bit higher. The density of the atmosphere is four times higher and the gravity is one seventh.
So that means I joke that if you had like um leonardo da vinci's flying machines um they would have worked on titan he was just born on the wrong planet yeah if you have big enough wings and you flap them like I did and I ran I could like get a little lift so it's a lot easier to fly on titan and that's why we're doing it um and then the temperature in the middle of winter at the middle of night it's like and then in the middle of summer at the equator it's like so it's pretty
much the same temperature no matter where you are All right. So, ninety Kelvin in Fahrenheit because I know people are going to ask. Minus two hundred and ninety or something. Okay. It's cold. Really cold. Very cold. Very, very cold. Okay. Good. So, we're going to take a few questions from people. So, we have one from Zap. Oh, my God. Every time you ask a question and every time I have a heart, I'm saying the name. Zapfan, Zapfan. Does the original material melt and therefore disappear?
So the bedrock, the rocks, if you were walking around on Titan and crunching sediment under your boot, is probably water ice. And at ninety Kelvin, it's as hard as rock. So it wouldn't melt. Um, what might be happening? There's two sources of sediment. So there's another source from the atmosphere. And if you have these organic sediments raining out, that is what the dunes are made out of. There is some of them in theory that dissolve in liquid methane. So not melt, but dissolve.
And that would be one way to not have river. You would just dissolve the landscape. Um, and you do have dissolution landscapes on earth. Um, and some of those rivers don't have anything at the end, because again, It's just all dissolved in the fluid itself. So that would be one way. Yeah. There isn't a lot of dissolved material produced over the age of the solar system. So it would be harder to do. But that is one hypothesis. Yeah. All right. So there is more questions.
So if you have more questions, don't hesitate to ask. We can even talk about drive and fly. In fact, I have a question for drive and fly. So did they map already the location, the landing site? So you still arguing and discussing about it? No, we are going to. So the mission is mostly chemistry focused and we're going to the south end of an impact crater called Salt Crater. It's near Titan's equator, very far away from the poles and the active rivers.
And the plan is to land in the dune field just to the south of the crater. We don't know how hard the surface is or the slopes and all these things. We don't have really good data like we would on Mars, for instance, or the moon to build super precise maps and where all the big rocks are. But the nice thing about dunes is that they're predictable, right? It's just a big pile of sand. You know what the slopes could be. They can't be that steep.
And so the plan is to land in between two dunes and kind of start and get our feet wet in that dune field and then move north towards the crater. Because what we want to investigate is places where water and organics might have mixed and for how long and what chemistry happened. We don't know any of that chemistry, right? And so an impact crater on Titan is great because you would melt all that ice.
So you'd have liquid water and organics at the surface in a warm water environment for potentially a while. And you want to kind of see how far chemistry can go. So that's the main goal of the mission actually is to investigate those, that chemistry. Are you going to land on the Delta or on the, on the, the only Delta or the only Delta is at Titan self along a lake. So we'll never get there. No. We'll go to the crater and then I don't know how long we can go after that.
Yeah, the plan is to just get to like the edge of the crater basically right now. There could be similar sedimentary deposits coming off of the crater and those are the ones I'm really excited about. Maybe they're there, maybe they're not. We definitely can't see them. If you look at the data, it's like super noisy.
maybe there's something there in theory there should be so that's what I'm excited to see all right uh there is uh so what's the next thing for you you um what are you gonna where are you working on I mean dragonfly is landing in what in two thousand thirty oh don't quote me on that one um let me google it nine years from now Yeah, something like that. So you have nine years. What are you going to do in the nine years, the coming nine years? First, I mean, continue.
We've gotten to the point with Cassini where we've kind of figured out what's on Titan's surface and what isn't. The next step is trying to figure out what's going on. And this is where we're moving into theory land and modeling and experiments. And also experiments to figure out what are the different rocks like? What are Titan's materials? How do they behave? If you stick some of these organics that are produced in the atmosphere and methane, what happens, right? Nobody's done that.
And so there's a lot of fundamentals now that we kind of know what's there and are starting to figure out what these things are. how do they behave? Why do they produce things that look the exact same as here on earth? But once you do this very simple math, you're like, oh no, that's way different. And so we're kind of at that point now where we have to use the data that we have to figure out what's actually happening and come up with new theories that we can test with Dragonfly.
Does that kind of answer your question? There's a lot to do. There's a lot to do. So I check it's landing. The landing is scheduled in two thousand thirty four. The launch is in two thousand twenty eight. Are you going to go to the launch? Hope so. It'll be fun. OK. I've never seen a launch. So, you know, I don't I'm not going to ask you which rocket launching it because I don't know. To be honest, I don't know. But yeah, it's going to be an amazing mission.
Because it's going to be basically the first mission we send, which is only, I mean, we have sent an helicopter on Mars, but we never send a mission, which is itself flying. I mean, the entire mission is the octo, how do you call it again? Octocopter? Octocopter. That's the entire mission. It's the size of what? It's three meters by one. I've seen it. It's the size of like a minivan. Yeah. Basically. Basically. It's huge. Very impressive. And yeah, we went zero to sixty here.
Like ingenuity was super tiny. It was like the size of my water bottle. Really tiny. It was a tech demo. Can we fly on other planets? And then we're like, yeah, let's fly a one-ton minivan. Far away from us in a super cold environment. It's going to be amazing. That's what NASA does best. I mean, come on. Someone has to do it. It has to be NASA. Yeah. Good. All right, well, thank you very much.
Is there anything you want to add about, oh, where can we have information about your research and read about your work in general? Yeah, I don't really have any social media. I'm a curmudgeon like that. So we have to read your scientific paper? No. Yeah, I mean, Google, but geomorph. Oh, I don't even know my own website. Google Sam Birch Brown. I'll be there. Okay. I will find you. Yeah. Thanks for having me. This was fun. Thank you.
Thank you very much for coming to tell us a bit about the wonder of Titan and the fact that there is no Delta and you have been looking for them. But it's okay. It's part of science. And I like the fact that we have people who come sometimes to tell us about the fact that they would be looking for something and they did not find it. because that's the way science works. It's not only flashy, amazing results.
Sometimes negative result is important result because it shows that we don't have a clear understanding of the system yet. And that's good. There'll be some cool stuff to discover in the future. Exactly. So perfectly. And you will make them with the Dragonfly mission. All right? Cool. Thanks so much. Thank you. Thank you to all our viewers for watching us. I saw there are some people who joined us from Canada and other parts of the world. This is the City Life from the City Institute.
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Visit our website. You can also enroll to receive our newsletter called Journey, where you hear about all the amazing research we are doing here at the SETI Institute. And yeah, thanks again, Sam. See you in five years to talk about the launch of Dragonfly. I hope to be invited as well, by the way. me on the guest list okay thank you again and uh see you next week for another video bye-bye you