Planetary Radio: Space Exploration, Astronomy and Science - Dunes, Walnut Shells, Alien Impostors and Other Worlds: A Visit with Sarah Hörst

Episode Date: March 27, 2019

A very special, extended conversation with Johns Hopkins University planetary scientist Sarah Hörst is capped by a tour of her fascinating lab. That’s where Sarah and her team simulate decidedly un-Earthlike atmospheres and more. Emily Lakdawalla has returned from this year’s Lunar and Planetary Science Conference with news from around the solar system. Caffeine! It’s on Saturn’s moon Titan AND in the espresso made on the International Space Station! More about the latter in What’s Up. Learn more about this week’s guests and topics at:  http://www.planetary.org/multimedia/planetary-radio/show/2019/03027-2019-sarah-horst.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The Dunes of Titan and the Air of Other Worlds, this week on Planetary Radio. Welcome. I'm Matt Kaplan of the Planetary Society with more of the human adventure across our solar system and beyond. I've enjoyed every interview I've done for this show. Some of them run long. It always makes me uneasy when an episode approaches the hour mark because your time is valuable. But now and then, there's a conversation that makes a longer visit seem just right. That's the case this week with Johns Hopkins University planetary scientist Sarah Horst. Let me know if you agree. How does caffeine in space come up while talking to both Sarah and to Planetary Society Chief Scientist Bruce Betts? Stay with us and you'll find out. First up, a report from

our Senior Editor Emily Lakdawalla, who just got back from a big meeting in Texas. The Lunar and Planetary Science Conference, it's one of your favorite stops every year, isn't it, Emily? It absolutely is. I've been going for 20 years now. Almost every year, I see all my friends from grad school. And ever since, we catch up on our families and on great science. It's just a fun meeting. We're going to put a link up to the conference, looking back at the conference, partly just because the photos are so great. It looks like everybody was having such a good time. Everybody has a great time when they get together. And especially when there's a lot of great science going on.

There were new results, first results from the InSight lander on Mars, from these two missions to asteroids. There was a celebration of the 50th anniversary of the Apollo 11 landing with a whole day long session looking back and also looking forward. It was just fantastic. We're not going to get to go into much of this at all in any detail, but how about those asteroid missions? Yes, there are two asteroid missions at near-Earth asteroids getting ready to grab samples. One of them has already grabbed a sample. I'm talking about OSIRIS-REx, which is

the NASA mission at Asteroid Bennu, and also about Hayabusa-2, which is a Japanese mission at Ryugu. They both showed up at asteroids that look remarkably similar. They're these top-shape asteroids with very bouldery surfaces. The top shape has to do with them being rubble pile asteroids. The bouldery surfaces probably go all the way through. They found that both of the asteroids have very low densities, about 1,200 kilograms per cubic meter, if you're interested. What that means is that they're made more than 50% of empty space. So they really are just jumbles of boulders collected together. The weirdest thing, the weirdest fact

that I enjoy repeating about results that were discussed at LPSC is the one about Ryugu. Ryugu is probably the darkest object ever explored in situ by in context, like asphalt blacktop has a reflectance of 8%. So this thing is like five times darker than asphalt. It is so incredibly dark that their instruments actually had the laser altimeter had a hard time getting reflections from the surface initially, but they figured out how to make everything work. And of course, they successfully grabbed a sample and they released some new videos of that process. And they're just amazing. You told me that there was also interesting news from Curiosity on Mars. Yes. Well, of course, I follow Curiosity very closely. And so this was the first meeting where there were results from Curiosity's exploration of the place called Vera Rubin Ridge,

which was identified from way before the landing, from the time of this landing site selection as being an interesting place for Curiosity to visit, because from orbit, there is a very strong signature of the mineral hematite, which is related to liquid water. One of the interesting things about Curiosity is that it's been finding hematite all the way along as it approached the ridge. It's just that it seems that the ridge either has a coarser-grained kind of hematite that's easier to detect from orbit, or it's just so windswept that there isn't dust covering it. So it turns out the hematite ridge doesn't really have any more hematite than the rest of the rocks that Curiosity has explored, just a little bit more, a little bit more. But one of the interesting things they've been looking at on the ridge

is that some of the upper rocks on the ridge, they're either gray or they're red. It has this patchy appearance to it. They're now pretty certain that the gray and red patchiness is not something that happened when the rocks were laid down, but is caused by groundwater percolating through the rocks after they were laid down. And the gray stuff has had the iron leached out of it and deposited in these beautiful hexagonal crystals of coarse-grained gray hematite in veins that are inside the rock. And so they're seeing evidence for all this kind of groundwater interactions with the rock after the rocks formed, which of course was long after the rocks were sedimentary when they were first laid down. So water was involved in these rocks formation and evolution at multiple times throughout its history. Fascinating stuff. What was your panel about and Planetary Science Conference, there is a Women in Planetary Science event. And I was very honored to be invited to moderate a panel of three women who had been

involved in lunar exploration since nearly the beginning. There were two women who have worked in the Astro Materials Curation Facility at Johnson Space Center. That's where they preserve and handle the moon rocks and the Genesis samples and the Stardust Solar Wind samples and even some samples from Hayabusa, the previous Japanese sample return mission. And so those were Judy Alton and Andrea Mosey, who work at JSC. And then there was Carly Peters, who's a planetary spectroscopist and one of my former professors at Brown University. And it was just a lovely conversation. Those three women have great stories. They're very different stories and mostly very fond memories of working in planetary science. Andrea Mosey was just a delight to talk to. She absolutely loves her job

and they love being able to preserve these great rocks from or brought back by the astronauts and facilitate the kind of science that Carly does in her work. She talked about how scary it is to get Apollo samples because she works with these dusty samples. And she said, you're afraid to breathe. You're afraid you might sneeze. You don't want to drop anything. And everybody laughed, but they were an absolute delight. And it was a great opportunity to interview them. Very timely conversation with that 50th anniversary coming up. Speaking of the moon, did you get to walk on it? We did. So there's a project, they did Mars first, and then it's out of ASU. And they printed a very, very large printout of a lunar map. I think they're using the same material that they use

now to wrap billboards. And so they emptied out one of the conference halls, one of the ballrooms, and they spread it out on the floor and invited people to walk on it in their socks. And so people were finding all kinds of favorite spots on the moon, either landing sites or favorite craters that they'd researched. I went and found the landing site of the Chang'e 4 mission, and people were just having great fun. And yes, indeed, some people did attempt to moonwalk on the moon. I love it. My favorite shot, and maybe we'll steal it from the site and post it at planetary.org slash radio on this week's show page, are all these people pointing with their sock and clothes toes, and they're all space socks, by the way, at the lunar North Pole.

It really did look like fun. I was pretty envious looking at all those pictures. You got to come next year, Matt. I'd love to. Thanks, Emily, for giving us this virtual visit to this year's LPSC. My pleasure. My pleasure. That's Emily Lachtwala, Senior Editor for the Planetary Society,

Editor-in-Chief of the Planetary Report, that March Equinox edition. You can now read online at planetary.org, our planetary evangelist. Hey, Emily, before I let you go, we're going to be talking to Sarah Horst in a moment, and I know she's one of your favorite people. I can't wait to listen to this conversation. She's fabulous. It is terrific. I recorded so much great material when I visited the Johns Hopkins University Applied Physics Lab back in January. You've heard all of it now, except for a conversation recorded not at APL, but at the university itself.

It's on that beautiful campus that planetary scientist Sarah Horst does her work. I spent a delightful afternoon with Sarah, touring her lab and talking about the many topics that capture her fascination. She primarily studies atmospheric chemistry and complex organics, but those are just the start. You're about to hear her cover such varied topics as her efforts to simulate the atmospheres of other worlds and the dunes of Titan and how walnut shells are helping to reveal their secrets, about the wonders of life and where to look for it, about alien impostors, and about the thrill of scientific discovery that drives her.

Settle in and then stay for a quick tour of her lab, including the stainless steel chamber she calls Phaser. stainless steel chamber she calls Phaser. Sarah, welcome to Planetary Radio, and thank you for making me welcome in this great office with all of your toys, your entire space collection, which you seemed a bit embarrassed by, but I think it's just science Disneyland in miniature in here. So this is great fun. To say nothing of your lab, which we will go back to in a minute.

You already showed me around a little bit. Thank you so much for having me. And it's nice to have you in my office that looks like it might belong to a 12-year-old and not a professor at a university. It would be a 12-year-old who's in love with science. I can say that. Yes, no, that's absolutely true.

Particularly planetary science. I mentioned your lab, which is literally across the hall from where we are now. What would you give to have a lab of some kind, maybe like that, on the surface of Titan? A lot. I would give more than I think I will ever possibly have. Although it's funny that you mentioned that because, in fact, the place that I would really like to have that lab is actually the moon. Yeah. We were, you know, when we were in the lab, we were talking about some of the issues that we have with Earth's atmosphere. It would help us with a lot of our experiments if we didn't have Earth's atmosphere to contend with. So I'm always kind of joking. It would be lovely if someone would build me my lab on the moon. Yeah, well, because then we wouldn't have to deal with Earth's atmosphere.

Of course, it turns out that Earth's atmosphere is a little bit important for those of us who, you know, need to breathe it. So, you know, it's kind of six in one, half a dozen or the other, either we are fine, and the experiments are challenging, or the experiments would be easier, and then we would have some challenges. So... Well, I was going to say, don't hold your breath for that laugh on the moon, but I don't know. Holding your breath would actually be quite useful. Yes. You might just, you might make it someday.

Maybe someday. Things keep moving forward. Maybe someday. With the, at least not yet, ability to do this on Titan, much less the moon, or maybe I should have said the moon, much less Titan. You're trying to simulate it here. I mean, we were just looking at that gorgeous little stainless steel chamber. Yes. Yeah, it's true. We can send spacecraft places and we build these big, beautiful telescopes and those missions have so much to tell us and we can build computer models and, you know, run all different kinds of cases and all of these other things.

But I think one of the really important pieces of planetary science that people don't always think about is the fact that we, you know, we have laboratories on Earth and we can build small versions of an atmosphere or an ocean or a volcano or all of these amazing things that people do in planetary science and very, very tightly control the conditions, and change one variable at a time and see what happens. Or we can use these places to test material properties, or to make analog materials that we think might be similar to the particles in Titan's atmosphere, or the composition of Europa's ocean and use those

things to test instruments, test capabilities of instruments, to test materials, to test sampling systems, all of these things. And so having this ability to build these little planets and moons in labs here on Earth is really, you know, one of the crucial pieces of the puzzle to being able to figure out how planets work. And so it's exciting to be able to have my own little lab just across the hall from my office where we can do these things ourselves. So as exciting as that stainless steel chamber is all of the stuff that feeds into it, which you said was built here on campus at JHU, Here on campus at JHU, which allows you to mix these gases, which we are, which you are doing to simulate the atmospheres of other worlds. Yeah, it's really cool. So we're, the chamber that you saw, the experiment that you saw is about four years old.

That actually makes it one of the newest of these experiments in existence on Earth. And so when we built it, we had the advantage of already knowing a lot of the major results from Cassini. We had the advantage of not only knowing that extrasolar planets exist, but already having some idea of what their temperatures would be like and what their atmospheres might be like and all these other things. And so when we built that experiment, we built it with the idea of being able to simulate any atmosphere in the solar system and a large chunk of the atmospheres of planets around other stars. That means that we can basically make any atmosphere you could think of right now today if you wanted, because we have all the different gases in the lab right now. We can mix them in whatever ratios

you want. We can run at temperatures from the surface of Titan or almost Pluto atmosphere temperatures all the way up to the temperatures at the surface of Venus if we wanted to, or some of these warmer exoplanets. And so we can study whatever atmosphere we want, and we've really been taking advantage of that. So the experiment that's running today, you saw Titan, which is kind of our standard. It's my first love. It's the one that the most work has been done on in these types of experiments.

But we've done Venus, Triton, Pluto. We've done a ton of extrasolar planet experiments at this point for the past couple years. And so we really can do this huge range of atmospheres, which has been really, really fun. And just all kinds of exciting science has been done so far and will do in the future. When we peeked through the little window in that chamber, there was this lovely violet glow. Because that's yet another factor that you can control. Talk about that. Yeah, the other thing that we control is we can control the energy that goes into the experiment. And of all of the things that we have to worry about in terms of simulating an atmosphere in

the lab on Earth, the energy source is the hardest. I'm constantly joking that if somebody could build a little star for me to put in my lab, I would really like a miniature sun. But if we're going to go to the trouble of building a miniature sun, what I would actually like is one that has a little dial so that I can change the stellar type for the exoplanets. They're working on that, you know. It turns out to be a little bit more challenging. And now everyone is like, oh, well, you can do that with LEDs. And it's like, yeah, you actually could do a pretty decent job at this point of simulating the spectrum using LEDs. But we need a fairly high flux of photons coming out of these things, which you can't really get from an LED. And so

that's really one of our biggest challenges is to say, okay, you know, we have gotten this perfect mixture of all the different gases. It's at the right temperature. It's at the right pressure. Now we have to put energy into it to simulate the chemistry, which is what we're really interested in. And that turns out to be one of the biggest challenges. So the way that we get around that is we use two very different energy sources in the lab. The one that you saw running today is a plasma, which is energetic electrons. And they run into the methane or the nitrogen or whatever. They break it into pieces. Those pieces are very reactive.

They start building new molecules. The other option is an ultraviolet lamp. So just a lamp that provides UV light, and it's hooked up to the chamber in the same way. And so then instead of using the energetic electrons, we're using energetic photons to break up the molecules and start the chemistry. up the molecules and start the chemistry. We use those two very different energy sources to kind of help us see, okay, how sensitive is this experiment to the energy source? Some of the experiments are very sensitive to the energy source, and so that means that we have to think really, really hard about how to apply those results to a real planet, because we can't yet at least have a star in my lab. And so we have to be very, very careful.

Some of the results that we see don't care. Either way we run the experiment, we get basically the same answer. And so we take that to mean that the energy source is not the most important characteristic of that particular experiment, that maybe the gas mixture matters more or the temperature matters more. Something else is really defining what happens in the experiment. That's one of the ways that we try to get around it. And I would say that's, you know, that's kind of a typical way to approach some of our scientific challenges. If we can't do something perfectly,

instead, we try to do a range of things and see how sensitive it is to the thing that we can't do correctly. And so that's what we do to try to make a star in the lab. We never provided the cute name of that chamber. So it's PHASER, which stands for Planetary Haze Research. I tried to crowdsource the name on Twitter at least four or five times and got a whole bunch of hilarious and snarky acronyms that were not at all useful to me. And when we finally settled on Phaser, then we had a very, very long debate about whether it should be Phaser with a Z for Haze or Phaser with an S for Star Trek. It turns out that one of the things that's really nice about having your own lab is that you're the decider. And so despite the fact that there were a number of votes for the S for Star Trek rather than the Z for Haze, I got to decide.

You went the right way. It still honors Trek. It honors Trek. And also I feel like Z is a really amazing, extremely underutilized letter. And so it's quite pleasing to have it involved in the chamber. But it was kind of this like last minute. So we had been talking about it forever, ever since we very first started working on the chamber. And then all of a sudden we were getting ready to submit a paper.

And I was like, oh, no, we have to name the chamber now because we have to put it in the first paper that talks about it. And so there was at that point a whole bunch of options on the whiteboard and we were brainstorming acronyms and finally settled on one. I'm trying to resist making references to Purple Haze, of course. Everyone sees that Purple Plasma and starts making references to purple haze. So you wouldn't be the first one. The fact that it's creating a haze, that's pretty key to all of this, right? Why are hazes so important? Yeah, that's a great question.

You know, I mentioned that, you know, the experiment we put energy in, it breaks up the molecules, they make new molecules. Depending on what gases we put into the chamber and the temperature and the energy and all of these things, sometimes that chemistry keeps going until it makes a solid. So in the Titan experiments, it always keeps going to make a solid. These solid particles we think are at least somewhat similar to the solid particles that we see in Titan's atmosphere. So one of the reasons why we can't see down to Titan's surface is because Titan has this very thick global haze layer. So it's kind of like the worst day you could possibly imagine in Los Angeles. And it's very similar, actually. The smog in LA or in other major cities is from photochemistry. It's from chemistry driven by

the sun. Different molecules involved and different consequences, but the same basic process. The reason that we care about haze for Titan or for any other planetary atmospheres is there's multiple reasons why. So one of the first reasons is that particles interact with light differently than gases do. Having particles in an atmosphere, whether they're a haze or a cloud or dust, affects the way that light moves through the atmosphere. So it affects the temperature structure of the atmosphere, what photons get to the surface. And so, you know, if you're thinking about the early Earth, that would have an impact on what photons were available for plants and what photons, especially the real energetic ones,

might be getting removed before they could do damage to DNA and RNA and things like that. And so the kind of first reason we care is it really affects where in which photons end up in an atmosphere and on the surface. And you could even envision cases in which having a haze layer or not might determine whether or not there is the possibility of liquid water on a surface, for example. So that's one reason why we care. Another reason why we care, especially in the case of Titan, is that these molecules in the haze in Titan are very complex and they're organic. So they have carbon in them. The molecules in Titan's atmosphere we know also have nitrogen. They have hydrogen.

Those atoms are part of a very small set of atoms that form the building blocks for all of life on Earth. The building blocks of DNA and RNA, which are called nucleobases. The building blocks of proteins, which are called amino acids. All of life on Earth is built on a very, very, very small set of molecules. And that small set of molecules is built on a very small set of atoms. So I'm less surprised that you get amino acids, but nucleobases, nucleotides, the real, like you said, building blocks of RNA and DNA. Yeah. So we have found in these experiments that we run that we make amino acids, we make all the nucleobases that life on Earth is based on, so adenine, cytosine, the ATCG that we all learned in school. The question that we have at this point,

though, is how much farther does that chemistry actually proceed? And so we can run these experiments in the lab and we can analyze the material that we make and look for things like amino acids and nucleobases. But what I really want to know, not just are those molecules present in Titan's atmosphere, which I think they are, whether they're present in trace amounts or whether they're present in larger amounts, we don't know yet. But I would at this point bet a lot of money on the fact that those molecules are present in Titan's atmosphere. They're present on the surface. But how far did that chemistry proceed? And that's been one of the big driving questions of my career so far, and I think going forward, is how far can organic chemistry proceed in the absence of life? And how far can it proceed in

the absence of life in an atmosphere? There's two reasons why we care about that question. One reason is that this material that we share in common for all of life on Earth, it has to have been around at the beginning for some reason. There's some reason why that became the fundamental set of molecules that all of life on Earth is based on. But we don't know where it came from. We find these molecules in meteorites and comets. You can make them in hydrothermal vents in the lab. People do hydrothermal vent experiments and you see them made there. And so we see that they get made everywhere, but we don't know what the source was.

But there must have been a source. That's one reason why we want to know how far the chemistry proceeds. We also need to know where did it stop without life? At what point did life have to have existed to make the processes keep going? And that's going to help us understand a lot of questions about the origin of life. The other reason why we care about answering that question, we're thinking about Europa Lander. We're thinking about using James Webb to look for life on planets outside of our solar system. We're talking about using James Webb to look for life on planets outside of our solar system. We're talking about Dragonfly to go to Titan to see if Titan is or was or could be habitable or inhabited. Dragonfly is that little drone quadcopter that-

Proposed to go. Yes, right. Has been funded. Proposed to go to Titan. But to do all of those things, all of the ways that we're talking about doing life detection, we're not assuming we're going to get lucky and have some elephant go tromping in front of a camera or do whatever. I mean, that would be much easier. We're assuming that we're going to have to look for chemical signatures, right? of the surface at Europa and we put it through, you know, really sophisticated instruments or dragonfly or, you know, looking at the spectra of these exoplanet atmospheres, our idea is that we're going to be looking at molecules to look for life. And so to do that, we really have to have an understanding of what molecules can only exist if there's life and what molecules exist

on their own in nature, on the surface of Europa, or in the atmosphere of one of the Trappist-1 planets, we have to start to really get a robust understanding of where the line is between molecules that get made by processes that occur on whatever planet you want to talk about, and molecules that only exist if there's life on that planet. And so that's one of the things that we're interested in studying and trying to understand. We know there's complex organics on Titan, but what does that actually tell us about the possibility of life on Titan? That's one of the things that's really beautiful about doing these lab experiments because

we can take this material that we make and run it through any instrument you want on Earth. And we've run it through a lot of them to try to figure out what's in there. And that also helps us figure out what instruments we need to send to Titan to say, okay, well, if we run it through this instrument, we don't learn very much. But if we run it through this instrument, that tells us a whole lot about the chemical composition. And this was the – it wasn't a mistake because we just didn't know any better. And it was, they were wonderful spacecraft. But this is what happened with Viking on Mars, right? We didn't know enough about Mars.

And so we got back these ambiguous at best results from the life detection. Absolutely. So people tend to talk about the life detection experiments on Viking as if they were a failure. You know, a lot of really amazing work on Europa, when he talks about Viking, he always says, the Viking life detection experiments would have been a failure if we had found life on Mars. Right? If the next time we went to Mars, there were bacteria everywhere and all of these things, if we had all of this evidence of life on Mars now, then we would look back at Viking and say, whoops, like we did it wrong. But the fact of the matter is we haven't found evidence of life on Mars yet. And so the thing that happened with Viking is that we didn't know the composition of the surface, which makes sense because we hadn't spent 30 or 40 years exploring Mars at that point.

sense because we hadn't spent 30 or 40 years exploring Mars at that point. And so we didn't know that there were these molecules called perchlorates, which were discovered by Phoenix, have been confirmed by Curiosity and some other Mars missions. When you put perchlorates and organics into an instrument and heat them to very high temperatures, which is what Viking did, you destroy all of the organic molecules in your sample. So we learned a lesson. Curiosity has a different way of analyzing the organics that doesn't require heating them to such high temperatures because we know about the perchlorates.

It's one of the things that's really frustrating about planetary exploration is that every time we go somewhere, we learn something new. And one of the things that we learn from going somewhere is that we probably should ascend a slightly different spacecraft. And so we learn and we try to, you know, build on our discoveries and send different spacecraft. But sometimes that means the pace of exploration can be frustratingly slow, especially when you're talking about studying the outer solar system,

where you're not necessarily getting to launch a spacecraft every couple years to go explore. And so it took us a long time to be able to actually use the discoveries from Voyager to actually learn more about the Saturn system with Cassini. And it will, again, take a long time to be able to leverage the things that we learned from Cassini to explore the Saturn system further. But every time we go somewhere, we learn something new. And the thing that's actually really neat about that is that then we can go back and actually look at the old data again. And so there's been a ton of reanalysis of the Voyager data now with our understanding. Viking data.

No, Voyager. With our understanding from Cassini. No kidding. There's been a ton of reanalysis of the Viking data with the understanding that's come from further Mars exploration. And so those data are so, so precious. We try and we're trying to do better now than we have in the past to take really good care. You might think, how could the Viking data be useful to us now that we've had all of these much more technologically advanced spacecraft at Mars? and we've been to Mars so many more times now. How could those data be important? But every single data, every single piece of data that we take in planetary exploration is so precious.

It's a moment in place in time that will never exist again, an instrument that we may never fly again. Every single time we get more information, it provides us an opportunity to go back and look at the data that we had before with a different understanding and see if there's more things in there that we didn't know at the time. And it's, you know, it's been done with all the Mars data. There's been some really beautiful results looking at the Voyager data being reanalyzed with both with our Cassini understanding, new technical tools, new lab experiments that have been performed. A couple of members of my group with some people at NASA Goddard were reanalyzing the data taken

by the gas chromatograph mass spectrometer on the Huygens probe. So those data were taken in 2005, but we have new computer tools, new understanding of Titan's atmosphere from Cassini. And so we asked NASA, what do you think? Can we take another shot at this beautiful data set? Because we still think there's more information in there that we couldn't get at at the time because we just didn't have all of the pieces that we needed. And NASA said, sure. And so now we're working on, you know, reanalyzing those data too. Important lesson in all of that. I want to go back to the earlier theme, one of those two things you say that we should have learned, because it resulted in this paper, which we'd already arranged to talk during this trip that I've made to Baltimore and APL. But since then,

you had this announcement from one of your associates in your lab. It had this great title, Alien Impostors, which is kind of a warning. I mean, it's like you said, we better know what we're looking for if we're going to take these things as evidence for life. Yeah. So exoplanets are so, so hard. There's lots of different flavors of planetary scientists. I am the planetary scientist flavor of planetary scientists, which is actually quite rare. So all of my training is in planetary

science. My undergraduate degree is in planetary science. My PhD is in planetary science. I always tell people I'm a planetary scientist born and raised. What that means is I really love the solar system. I love the planets and moons in the solar system. I love the way that we can turn these points of light into worlds. That is why I got into studying planets. Exoplanets are interesting to me. We're just starting to turn these points of light into worlds, and it's going to be a really, really long time before we can do it the way we've done it in the solar system. For me, I'm still kind of more interested in what we can learn about the solar system by studying exoplanets. But one of the things that people are really thinking about and

talking about now, especially with the hopefully impending launch of James Webb, if you only have a spectrum of a planetary atmosphere, if you only know how light interacts with gases in a planetary atmosphere, how do you know if there's life there or not? Because you find 20% oxygen in the atmosphere. Right. So maybe you find oxygen. Maybe you find methane. But again, this goes back to what we were talking about earlier, as you mentioned. What molecule do you see and say, got it, that's it?

Or what set of molecules do you see? What molecule do you see and say, got it, that's it? Or what set of molecules do you see? One of the lessons that I think the planetary science community has learned from the solar system that I'm trying to remind the exoplanet community of whenever I have the opportunity is that sometimes we look at an atmosphere. Titan's atmosphere is a great example. Titan's atmosphere is the example I always use. Sometimes we look at an atmosphere, as we did from ground-based telescopes and from Voyager. We look at the

molecules in the atmosphere and we say, huh. And you build this super sophisticated computer model of all of the chemistry in the atmosphere trying to explain why this molecule is there and why that molecule is there. And you think about it really hard and you have all these observations all these measurements you look and you go huh and so the example for titan is a very very simple molecule um carbon monoxide co discovered during the voyager era nobody could explain it so you make this model of titan's atmosphere with all of the things that we know about titan all of the measurements that we have of the composition and the temperature and the spectrum of the sun and all of these things. You make these beautiful chemical models and they can explain perfectly the abundance of acetylene and perfectly the abundance of ethane and all of these other molecules in Titan's atmosphere.

And no one could reproduce the abundance of carbon monoxide. And people tried. Lots of different groups tried. They tried from shortly after it was discovered in the early 1980s, all the way through, you know, launch of Cassini, arrival of Cassini, nothing. Nobody could explain it. Maybe there was a comet that crashed into Titan relatively recently in solar system history that dumped a bunch of CO in, but that didn't really make any sense with some of the other molecules. Nobody knows. There's this temptation at some point to say, is CO, is that a biomarker? Is there life on Titan? You know, and you don't see that temptation necessarily published a lot in planetary science. But you know that the

conversation happened about is the only possible way to explain this life it's not life i mean there might be life on titan don't get me wrong but the carbon monoxide is not signature of life the carbon monoxide is the signature of enceladus so the thing that we didn't know from voyager the piece of information that was missing when people were putting together all of those models of atmospheric chemistry of titan the thing that was missing was Enceladus, which sounds ridiculous, but Enceladus is shooting a bunch of water out into the Saturn system. Some of that water ends up in Titan's atmosphere

and through photochemistry processes produces carbon monoxide. Fascinating. So this was the first paper I wrote as a graduate student. That's the one that's hanging on the wall above the door of the lab, right? We took this model of Titan's chemistry, which had been used for years, and we said, what happens if you put the water from Enceladus into the top of the model? And when you do that, you get Titan's atmosphere, carbon monoxide included.

It wasn't alive. The reason why I tell that story and the reason that this is relevant to the question that you tried to ask that I've been avoiding answering thus far, because that's my style, is that we are not going to know if any of these exoplanets have an Enceladus. Not for a long, long, long, long time. Just too small to detect. Too small to detect. And, you know, Enceladus is just kind of an example of the problem, which is that for exoplanet atmospheres, we are not going to know our boundary conditions. We're not going to know if there's anything coming in from the top of the atmosphere, whether it's Enceladus or comets or dust coming in from the remnants of an asteroid belt or

a moon that's been disrupted or rings. We are going to have a real, real hard time knowing what the boundary condition is at the bottom of the atmosphere. Is there an ocean? Is it volcanically active? Is it ice? Is it carbonates? Like what is the surface boundary condition? We will be able to measure the composition of the atmosphere pretty well, but when we are going to take our models to try to figure out if we understand the chemistry, which is what we're going to have our models to try to figure out if we understand the chemistry, which is what we're going to have to do to try to figure out if there might be life there or not, we don't know the boundary condition of the top or the bottom of the atmosphere,

which is really important. This kind of got us thinking about this problem. You know, you have this beautiful spectrum from James Webb, and it tells you, I'm going to make something up that might be physically impossible, but okay, it tells you that there's 10% methane and 15% oxygen and 20% nitrogen or whatever, right? It's not going to tell you that there are amino acids because it's not going to be able to detect them, even if they're there. It's not going to tell you anything about complex molecules. It's too hard to measure those from remote sensing. It's going to tell you our kind of bread and butter molecules of an atmosphere. It's going to tell us the ratios. And then we're going to have to figure out if those ratios are possible on their own. Without life. Without life. Or whether the only explanation

or the most plausible to the point that you would be willing to have the President of the United States stand in front of the world and say, we have found life on another planet? Is that the only explanation? And so one of the things that we started doing is running a bunch of experiments. So people have done a lot of this work with chemistry models. And I say this as a person who does chemistry models. Those models are only as good as the information that you put into them. For places where we have a lot of information, like Titan or Mars, we can do a pretty good job of reproducing the chemistry. But there's a bunch of choices you have to make when you run those models. And so if you don't have information about the place, it's not clear what the result

is. Garbage in, garbage out. Yeah, I mean, I wouldn't go, I don't want to go that far because I don't want to insult my colleagues. But, you know, the information that you to go that far because I don't want to insult my colleagues. But, you know, the information that you get out is only going to be as good as the information that you put in. And so there are limitations on what you get out if there are limitations on what you put in. You were more diplomatic. I try occasionally.

Although I definitely have used that phrase in reference to atmospheric chemistry models, including our own at various points in time. And so we thought one thing that we could do instead of running the models, and there's a bunch of really great people who are doing a lot of really amazing work on exoplanet atmospheres with these models. We said, let's run some experiments instead. So instead of saying, okay, well, do we have all the reaction rates in there? And are the cross sections correct? What happens if you change the temperatures? We're just going to put a bunch of gases in there and put energy into them and see what happens. We ran this whole set of different composition, different temperature, exoplanet, potential exoplanet atmospheres.

Right now, we don't have measurements of any exoplanet atmosphere that's good enough to do what we do here from a real atmosphere. So we can do Titan, we can do Pluto, we can do Mars, Venus, Saturn, Jupiter, whatever you want. But we can't do a specific exoplanet right now because there isn't enough information. There will be with Webb, we hope. But right now we don't have it. And so we did this big range. And one of the things that we found is that we make molecular oxygen in the presence of methane or in the presence of other organic molecules. The combination of those two things is often mentioned as a biosignature because those sets of molecules are out of equilibrium.

So if you left them alone in the chamber long enough, they would cease to exist. They would either convert all the way one way or all the way the other way because they're out of equilibrium. The thing about atmospheres that's really frustrating is they're perfectly content to be in disequilibrium for a lot of reasons. Titan's atmosphere is in disequilibrium because of the sun and because of Enceladus. Earth's atmosphere is in disequilibrium because of reasons. Titan's atmosphere is in disequilibrium because of the sun and because of Enceladus. Earth's atmosphere is in disequilibrium because of life. We have to figure out how to tell the difference between those two things. And it's going to be really hard. And so that was one of the things that our experiments showed was like, look, I'm 99.9% sure there is no life that we have created in this chamber. If we have, I'm very much looking forward to picking up our Nobel Prize. Yes, yes.

Congratulations. But I don't think that's what's happened. And so what that means is we need to think more carefully about what combinations of molecules we're thinking about as biosignatures, because some of the ones that people talk about a lot, we can make right there across the hallway together. And it's not the sign of anything other than some really interesting chemistry. So this is sobering stuff. I know, I'm such a downer. Well, it has to be a little bit of a downer to some astrobiologists out there and people who thought it was going to be easy to find signs of life. Before we move on from this, though, it's one of your associates, right?

An associate of yours in your lab it's a research scientist yeah who led this work yeah um what do you think of work that is underway elsewhere i mean i i had mentioned to you that not long ago we had uh talked to a couple of members of the team at mcmaster university up in canada yeah and they are doing some of the stuff that you're doing but going a little bit further in one way, at least, where they're putting little samples of stuff in little, little, on slides, basically, in there, and watching to see what happens if they get membranes, if they get the same kinds of complex molecules that you're seeing. Yeah, there's a number of different groups in the world that do,

you know, work like this or related work. One of the things that's interesting is that all of these experiments have different things that are good and bad about them. And so I think it's one of the things that's so exciting about having lots of different groups working on kind of similar problems. You know, there's things that our experiment is probably, and this is going to maybe come across a little bit as a little cocky or conceited, but there are things that we do with our chamber that is better than what anybody else could do. But there are things that we do that's not great. There are conditions that we can't simulate. There are questions that we can't really shed any insight on, and so we don't try.

And so then there's groups, other places in the world, where certain questions are maybe not really in their wheelhouse, but there are things that we can't touch that they, you know, are the world's experts at. And so we have lots of different groups all over the world trying to tackle the same big picture questions, but from lots of different points of view. And I think that's really important because at the end of the day, the only way that we're actually going to answer any of these questions is going to be a combination of not just different people, you know, working on lab experiments, but the, you know, the combination of these beautiful observations and the computer models and the lab

experiments and lots of different people thinking way too hard about all of these things until we understand more about how planets work. Many paths that perhaps must be taken toward the truth. Yes, that's absolutely true. Lots and lots of dead ends, but you learn something every time you go down the wrong path. And that's one of the reasons why we just, you know, get up again the next morning and go down this one instead. What's down this one? Nope, wrong. Okay, turn around, come back.

Ah, science. Yeah. I don't want to leave your first love. Okay. Because there are other things, we talked about this a little bit when we were in the lab, that fascinate you about this world, which of course we and so many others often talk about as being so similar to our own, other than the fact that it's frigid. But I mean, with all the systems that we share, hydrological systems, if you will, we were talking about dunes, which is something that your lab has also worked on quite a bit, because we know we've seen them down there on the surface. Yeah, frustratingly, they seem to exist, despite all of our best efforts to make them disappear, as I was mentioning to you earlier. Titan is amazing. Titan has all of these Earth-like

processes. And one of the things that's so beautiful about Titan, you know, at the end of the day, it may turn out there is not life on Titan. There has never been life on Titan. There never will be life on Titan. There can't be life on Titan. That may be the thing we eventually come to learn about Titan. I'm a little bummed out, but it seems pretty plausible. plausible. Even if that turns out to be the case, Titan has so much to teach us about Earth and about conditions for habitability, about how planets work, because it has all of these processes that you just mentioned. It has a hydrological cycle. It rains. There are rivers. There must be

waterfalls and rainbows and all of these things that we think about as almost being uniquely characteristic of Earth. But the materials are different. The liquids are different. The solids are different. And so that gives us the best chance we have, I think. I think that's really a true statement to test our understanding of how all of these processes work. Because we have all these equations that govern how dunes form. We have all these equations that tell you, how is a river channel gonna form? And why does it branch this way? And how much fluid can it move?

We have studied those processes on Earth for so long, we think we understand the physics. And the best way to test that is to take those equations that supposedly are fundamental to these processes and say, great, how do they work on Titan? And I can tell you right now, the answer is they don't, or at least they don't always. And so one of the things that's really exciting about that is that tells us somewhere in the equations, and you know, the people who study these things can point probably to where the issues are, there are things, numbers, maybe some constants, things that we have derived from studying these processes for very long on Earth,

that have within them something that is only on Earth and not on Titan, something to do with the material properties, something to do with gravity, something to do with the material properties, something to do with gravity, something to do with the atmospheric pressure, something that's different. And we don't know that it's there because the equations work on Earth. We never had to figure out what was in that constant. You just use it and you get the right answer. By using these same processes on Titan,

the dune formations, the rainstorms, the clouds, all of these things, they're going to help us really dive into all of these equations and figure out what things are trapped inside of them that we don't know about. And then we can pull them out and we can say, well, if you know that you're using these equations on Mars and on Mars, it's silicates and it's this and it's that and whatever, the equations will work perfectly because now we know. You want to take them to Venus? Here's how they work on Venus.

Here's how they work on Pluto. That's what we're trying to do at the end of the day. It might seem like we're obsessed with these details of exactly how this one lake formed on Mars or how this one process is working on Titan, but we're trying to figure out how planets work, period. So that the more, you know, when we're starting to look at these exoplanets, we're not starting from scratch every time trying to figure out how a planet works. The longer we do this, the easier it's going to get because we already know the equations. We can already predict what will happen.

We've been particularly trying to understand the dunes on Titan. I mentioned this to you earlier because features that are formed by wind on the surface of a planet, and I'm sure someone who is listening to this is going, Sarah, Titan's not a planet, it's a moon. Sorry, Titan does planet things. I'm going to call it a planet. My apologies. We really want to understand things like wind speeds. They're important for understanding how the atmosphere moves. That tells us a lot about climate. Where is it going to rain and how much and how do things get, you know, moved around on the surface. And wind speeds are very hard to measure. I know that sounds weird to people who live on Earth because you can just go outside and measure the wind speed. It's not that hard.

But to do it on another planet. Okay, so you send a spacecraft that has a wind sensor. Curiosity has wind sensors. One place. One place on Mars you have the wind speeds. Congratulations, you did it. You have the wind speeds one place on Mars and only as long as Curiosity is operating. When you have a planet that has an atmosphere that has a lot of clouds, you can track how fast they move. So that's how we measure the wind speeds on Jupiter and Saturn and Uranus and Neptune. We're looking at how fast the clouds move. That helps you because, especially Jupiter, for example, has clouds everywhere.

And so you can get really good idea of the wind speeds from looking at the clouds. Titan doesn't have that so much. Titan does have storms. It has clouds. They tend to be seasonal. And so they move location with season. And they don't happen super often. And so to measure the wind speeds on Titan, using clouds is hard. And so we were really excited about having all these features that were clearly created by wind on the surface, because that is a record of what the atmosphere has been doing in a way that we can't get from anything else.

And so everyone's like, ah, it's great. We're going to figure out, you know, how fast the wind speeds are and which direction and all of these things that's recorded in the dunes. And then everyone was like, wait a minute. We think the winds blow the other way. What in the world? The opposite of what forms the same. The opposite of what forms the dunes.

I mean, like literally the opposite. And then you start thinking like, do we have a sign error? Like what is happening right now? It was immediately obvious something had gone horribly wrong. And it wasn't clear what the something was. And so I don't think very many people know this, but there's a facility at NASA Ames called the Planetary Aeolian Laboratory. There's a number of wind tunnels there where they simulate sediment transport, sand transport, dune formation on other planets. So there's a Mars wind tunnel, which is called

MarsWIT. The Titan wind tunnel used to actually be a Venus wind tunnel. It got repurposed when we got interested in Titan dune formation. And so we simulate the wind transport of sediment in this wind tunnel at NASA Ames. And so people started working on these experiments at NASA Ames because the dunes on Titan didn't make any sense. They were clearly there. They didn't care that they didn't make any sense to us. But we were kind of mad about the whole thing. And so people started doing these experiments to try to understand how fast does the wind have to blow to move sediment on Titan? And then what does that tell us about these constraints that we've been getting from these models, what we see on the

surface and whatever else? And different sediments too, as you demonstrated to me, because you have that neat little display case that has the little vials of all these different potential sediments. Right. So the thing with these wind tunnels is that to simulate the movement of sediment on Mars or on Titan, we address the pressure inside of the chamber and the speed of the air moving inside of the chamber. And there's a way in which you can do that so that you can mimic the conditions on the surface of Titan or on the surface of Mars that are important in terms of the physics for moving the sand. The one thing that you cannot change in those wind tunnels that governs the physics of moving sand is gravity. Unless someone has figured out how to adjust the gravity of Earth, we run into problems.

And so the way that people account for this in the wind tunnels is by using different types of sand. that people account for this in the wind tunnels is by using different types of sand. So instead of using the kinds of sand that we see on Earth, silicate sands, you know, we have these beautiful black sands, basalts, all these different sands that we use on Earth, they use things that have a lower density. Because we don't actually care about the mass of the particle in terms of transporting it, we care about its weight. And so by changing the density, without changing gravity, we can change its weight. And so by changing the density, without changing gravity, we can change the weight of the particle. So the thing that people have been using for now very, very, very many years

in the Mars wind tunnel and now in the Titan wind tunnel that is lower density can come in a large variety of sizes, which we care about. Also has to be not toxic and relatively cheap to purchase in bulk because once you use an experiment once you run an experiment you lose your sand are walnut shells i was gonna say here comes the punchline i know walnut shells it's so funny to me because the first couple of papers that really came out of my lab when i started at hopkins were about walnut shells of all things i have to tell you never in a million years did I think that my research group

was going to be writing a whole bunch of papers about walnut shells. But here we are. So they have lower density. And so we use walnut shells to simulate sediment transport on Mars, sediment transport on Titan. This is, and we talked about this a little bit before, but this was where we came in and I said, hold on a minute. This is, and we talked about this a little bit before, but this was where we came in and I said, hold on a minute.

You got the pressure right and you have the wind speed right to do that part of the physics of sediment transport on Titan or Mars or whatever. You have adjusted the particle density so that your gravity is right. So we're, you know, everyone's sitting around here congratulating themselves about having done the physics correctly. But you're using walnut shells. And the dunes on Mars are not made out of walnut shells. Not that we know of. That we know of. I'm 99% sure the dunes on Titan are not made out of walnut shells that we know of.

How does that matter? How do the interactions between the walnut shells that are determined by their composition matter? And does it matter? Because it might not. And if it doesn't matter, then great. We can use walnut shells for the rest of forever to simulate these processes and it won't matter. But this was something that people had not done a lot of work on. And so my senior grad student, Shinting,

got very, very interested in material science and started looking at a lot of the properties. And so what she's been doing for the last four and a half years now has been taking all these materials that we use in the in the wind tunnels here on earth the walnut shells some of the other things i showed you were different types of sand which are also used because we understand vaguely how sand transport works on earth i actually didn't point out to you some of the other ridiculous things that we have in there. One of the materials that we were interested

in looking at are glass bubbles. They're very, very low density because they're hollow. Yeah. But then the material properties are better known and they're also more similar to quartz sand and glass are the same thing. That's what we make glass out of.

At least the composition would be the same. And so we have all of those different things. So Shinting has been looking at density and she's been looking at things like fracture toughness and elastic modulus and all of these different mechanical properties. She's also been looking at interparticle forces. So if you were to take two walnut shells, and she's done this, which I just still am, it just wasn't what I thought I was going to be doing with this period of my scientific career. But you know, if you take two walnut shells, and you move them very, very close together, is there any kind of electrostatic interaction? Is there a force that pulls them together? If you get them together? Is there a force? Is there a force that pulls them together? If you get them together, is there a force, is there a cohesion force or an adhesion force that keeps them together?

Because this matters. Because you have this wind that's blowing along the surface of these particles. And one of the forces that it has to overcome is the force between the particles themselves. And so Shinting has been using these, you know, nanotechniques to take one tiny walnut shell attached to this thing and one other tiny walnut shell and look and measure these very specific things. So she's used all the Titan wind tunnel materials, but then she's also been looking at a bunch of different organics, a big range of them, and then also the material that we make in our Titan experiment. So the experiment that's running right now is for Shinting. And so we take this analog material that we make, and she's been looking at fracture toughness and electrostatic forces.

And these are the tholins that you also had a little vial of that we looked at in there. Yeah. We'll put up pictures of some of this stuff on the show page at planetary.org slash radio. Yeah. So she's been looking at all of those things too. And one of the big things that she has found, and I forgot to mention this when I started, fell down this, you know, Titan dune hole that we've been talking about, but the dunes we think are made out of organics. We don't know how the particles get made. The dune particles must be bigger than the haze particles that fall out of the atmosphere. We know that. And so if the dunes are made out of haze, there must be a way to build those particles bigger.

Alternatively, we could have some organic kind of bedrock on Titan from all of this material having rained out of the atmosphere for so many years that then gets broken down into smaller particles. So the particle size we don't think exists naturally, and so it's either getting made by building things up from the particles that come from the atmosphere or breaking them down from material on the surface. But in either case, that material is organic because it's made by organic chemistry that happens in the atmosphere. This has been a question that we've now had for a long time. So the dunes have been stymieing us in a number of ways. Why are they the wrong direction? Where in the world do these particles come from?

Those questions might seem a little silly, but they really matter because they're telling us something really fundamental about the atmosphere and about the way the atmosphere interacts with the surface. Something bigger picture about Titan is hiding in these questions. Shinting started looking at this, and one of the things that she has found, and I think it's probably one of the biggest results from the work that she's done, these materials that we think make up the Titan dunes are not very strong. They don't want to be transported very far. On Earth, the extent of a dune field, how far the material can get transported,

really depends on what it's made out of. Because every time the sand particle hops, it experiences a little force, it gets a little bit rounder, it loses a little bit of its material, and that's defined by how strong it is. And so the weaker it is, the less it can travel, right? You could envision just having a suitcase, right? If you have this like big strong suitcase that can handle every airport you take it through on a number of trips. But if you have this suitcase that isn suitcase that can handle every airport you take it through on a number of trips. But if you have this suitcase that isn't very strong, one time through baggage claim and it's done. It doesn't get to go on any more trips.

It's never going to end up in Paris. It only gets through LaGuardia once or something and then you're done. That's one of the big things that Shinting has found is that probably the sand, whatever process it is that's making it, must happen where we see the dunes. Because it's very hard to transport it long distances. And the thing that's really interesting about that is we see the dunes everywhere on Titan. So they're centered around the equator, but they go to mid-latitudes in both directions and encircle the globe. And so if we can't transport sand very far on Titan, that means that the process that makes the sand must be happening basically globally. That screams that it's an atmospheric process, because that's one of the

main things that's global on Titan. But we're still trying to figure out what the process is and what that means for all of these questions. The other thing that we found out from doing these wind tunnel experiments, and this was a result that we weren't originally involved with, but have done some subsequent work, the wind speeds have to be pretty high to move particles on Titan, much higher than what we normally see. And so that actually turns out to maybe be the solution to this issue that we had of the winds going the wrong way. Because there is one time, sorry, two times a year at solstice, or sorry, at equinox, when the winds reverse at the equator.

And it's a very tumultuous time on Titan. We have big storms. The winds get much, much higher. It's a very short period of time relative to the rest of the Titan year, but it does happen. And so we think that the dunes are probably not actually recording the average conditions on Titan, but rather the orientations of the dunes are recording these very tumultuous conditions that happen during this just very short period of Titan's year when the wind speeds are higher and when they're the other direction. And so there was very tumultuous conditions that happen during this just very short period of Titan's year

when the wind speeds are higher and when they're the other direction. Yeah. And so there was something hiding in that information. It wasn't that we were wrong. Yeah, our models. It was that we were missing something. Big relief for our models. Yeah, so I think everyone is quite pleased now that it doesn't seem like we've completely

misunderstood how Dune formation works. But we still have a lot of outstanding questions about it. I got one more about Titan. Yeah. Which you've kind of nibbled at the edges of. And that is getting your thoughts about what you have seen of the models for life on Titan that some people have been playing with. Some people have been coming up with. Yeah.

That's a good question. I guess, and I should have said this when we were talking about amino acids and nucleobases before. If there is life on Titan, it almost certainly does not use the same set of molecules that life on Earth uses. For a lot of reasons, why would it? I guess is the first question you might have. But because it's so cold, there's no liquid water at the surface. Water is like a rock. Part of the reason why life on Earth has the specific biochemistry is because we're based on water. And so because of the low temperature, if there's life on Titan, the chemistry will be very, very different. Presumably, it would still be organic. There's lots of reasons why life is carbon-based. We don't necessarily want to throw the baby out with the bathwater in terms of, you know, thinking about what the chemistry might be.

And so people have been doing a lot of work to say, okay, fine. It's not water, so it's not going to be DNA. It's not going to be lipids, fatty acids, the way that we think of them here. But we think that some things are going to be fundamental to life. We going to be lipids, fatty acids, the way that we think of them here. But we think that some things are going to be fundamental to life. We need to be able to build little boxes that we use to transport stuff around. So cell membranes, things like that, because there's reasons why we use those things, right? We keep those things out. We keep these things in so that we can move them to this other place. And so one of the immediate questions that people had was, okay, well, how do you build a membrane? If you are not looking at liquid water, you're thinking about

liquid methane and ethane instead. Are there molecules, are there organic molecules that we think are present on Titan that you could use to build a cell membrane? That's a great question to ask. And so people who, you know, are much better organic chemists than I am, because I only play one on TV or on the radio, started, you know, thinking about this. And the obvious thing to do is to take molecules that are somewhat abundant, we think on Titan, and to see, like, could you make a membrane out of that? And so people have been doing that. And so at first, people were using some really sophisticated computer models to just see, like, okay, if you had these molecules arranged this way and they have this polarity and whatever,

like would that make a membrane or would everything just kind of fall apart? And they found some, this group at Cornell found a couple of molecules that seemed like they would happily make a cell membrane in the lake on Titan. There's people who've been doing lab experiments. What happens if we take this stolen material or some organic that we think is in Titan's atmosphere and on its surface and put it in liquid methane? Does it make itself into a spherical membrane? Does it self-assemble? And the answer seems to be yes. Wow. That's a big deal. It is a big deal. And so, you know, I think the thing that's interesting there is that that means there is a

solution to the question of a cell membrane. It doesn't mean that's the solution, because I think one of the most important things you learn as a planetary scientist is that nature is far more creative than we could ever possibly dream of being. But it means there is one way to make a cell membrane on Titan. So that question at least has one solution. Now, how would you make an information-containing molecule? Because DNA and RNA are not going to be useful in this particular situation because they're not going to fold correctly because of the temperatures. So there's a group in Florida that's been thinking about

how would you make an information-containing molecule out of the things we think are present on Titan? It results in some of the more entertaining conversations I've had over the past, I don't know, decade at this point, because, you know, the people who are doing these, this computational chemistry, they want to know what starting materials they have. And so they'll come to me and say, Sarah, what's in Tholin? And I repeatedly say to them, well, what do you want? Because one of the things that we've learned from studying this material now for, the reason for this word tholin is that they couldn't figure out what it was. They knew it wasn't just a polymer. So something that just has the same repeating chemical unit. And so they didn't want to call it a polymer because that's not what it was.

And so they wanted a word for this thing that they didn't know. And the quote is hilarious because in the paper, because it talks about how it's, this is an intractable polymer. It's been resistant to our attempts to try to understand what it's made out of. Back then. Back then. And I, and if Carl was alive today, he would, he would learn that it still has resisted many of our attempts to understand it. And so when these computational chemists come to me and say, well, what's in it? I ask them what they want. And they're like, well, I don't know, what do you got? And so we just sit there going back and forth, you know, not really, really getting anywhere, because there are so many different molecules in this material. And so it's hard for me to just say, oh, well, you can only have this,

because that's not the answer. It's a fun game. And actually, I saw while we were in the lab, somebody tagged me on Twitter, because this has become a game that we now sometimes play where someone for some reason will be interested in a molecule and they'll say hey is that in folem and i'll go pull up a chemical analysis recently i got oh yeah it looks like it's it's one of my collaborators um messaged me uh i't know, maybe a month ago and said to me, hey, did you know there's caffeine in tholin? And I messaged him back, and this is a good life lesson because I messaged him back in full-blown skeptical scientist mode. And I said, are you using caffeine to calibrate your mass spectrometer? Because it turns out that caffeine is an excellent molecule to use to calibrate your mass spectrometer.

And so I have seen caffeine in many, many, many of our data sets. But because we use it to calibrate the mass spectrometer. And so I have seen caffeine in many, many, many of our data sets, but because we use it to calibrate the instrument. Could be a contaminant. It could be a contaminant. And so I would never say, oh yeah, there's caffeine. He says, we don't use caffeine to calibrate our instrument. He's like, there's caffeine in Tholin. Fascinating. So we, you know, somebody, at some point, I think how we first, you know, started doing this on Twitter was, you know, when Breaking Bad was very popular. And at some point somebody tweets at me and says, hey, Sarah, is there methamphetamine in tholin? Like, oh, geez. It looks like there might be some little bit of. So there's all kinds of stuff in

this in this material. But that means that at the service of Titan, there's a very robust organic chemistry. There is the opportunity to have a whole bunch of different options in terms of how you might build a cell membrane or how you might build an information-containing structure. The question is, has anything figured out how to take advantage of that? This is certainly enticing. It is enticing. You have given me a tremendous amount of your time, and it has been delightful, not just because of the content of what you've talked about, but because of the passion that you bring to it. Thank you. As you know, that's a big deal to us on this show and in the Planetary Society and to our boss, Bill Nye, and to Carl Sagan, for that matter, our founder, one of our founders. I know from your past that you work with some great scientists,

several of whom have been on this show more than once, Ashwin Vasaveda and Mike Brown. What do you share in common with them and with other people who bring so much passion to this work, other than that passion. I think if you talk to most of the people in this field, what you find is a whole bunch of people who, when they look at the night sky, get really overwhelmed by wondering what's out there. It's not always about, you know, are there aliens there? Is there life in the solar system? Are there creatures on Mars? That, those questions, that question, maybe the question, are we alone, is something that a lot of the people in the field are interested in, but not everybody. But I think the thing that everybody has in common is that at some point in their life, they looked up at the night sky

and were so overwhelmed by the questions that they had, which I think are common among a lot of people who look up at night, but they were so overwhelmed by the question that they had to do something to try to answer it, that they weren't content to read about the things that other people were finding out, that they themselves had to get a bigger telescope. And, you know, use the example of Mike Brown. And I feel like if you were to track Mike's career, at some point, it was just a process of getting access to bigger and bigger and bigger telescopes, because the questions that he desperately wanted to know the answer to required a bigger telescope. You know, you mentioned Ashwin, who, you know, is the project scientist for Curiosity now.

And former director of JPL. So when I worked for Ashwin, Curiosity was a napkin drawing, effectively. I mean, it was slightly more than that. That's a little bit unfair. But, you know, I was working for him. Curiosity was just kind of almost like a twinkle in the eye of the people who were building it. And so it's been amazing watching the process of that all happening. And I think Ashwin would say the same thing. You know, we just want to know how planets work. We just want to understand more about how our own planet works. and we want to know what else is out there. What are the weird options? What are the possibilities for life? What does this mean for the past and the present and the future of our own planet? And what does it mean for all of these other worlds all over the universe? And we know now from Kepler that there are, at least in our galaxy and probably in the universe, more planets than

there are stars. And I try not to think about that very often because it's just a lot of work. I vividly remember we had a happy hour of planetary scientists that happened the day that they had made this announcement from Kepler that they could now statistically say that there are probably more planets than stars in the universe. And everyone's kind of giddy. I mean, this is exciting, right? The possibility for life, the types of planets that are going to exist, this is exciting as a planetary scientist.

And there's one person sitting in the middle of the table, and I cannot for the life of me remember who this person was. And they're just sitting there just crestfallen. You know, everyone else is like, ah, this is exciting. It's cheers. Let's have a beer. Let's do this. One person is just sitting there. And finally, somebody just looks at him and says, what's wrong? Are you okay? And the person goes, I started out in astronomy. And the reason that I started studying planets is that there were too many stars. What are we going to do? And it was just this funny moment. Because I think my first thought was, well, we're just gonna have to figure them out. Isn't this a beautiful time to be here? Because not only are we to the point where we can look up at the night sky and ask these questions,

how many planets are there in the universe? What kind are they? Is there life there? But we're getting to the point where we can start to answer those questions, where we can have looked up in the night sky with the spacecraft that we built as humankind, and we can say there are more planets than stars. We can do that. We know the answer to that now.

We don't have to look up at night and wonder because we can answer that question. So what's the next question and the question after that? And I think that means that this is a very unique time in human history. We don't just ask the questions. We can start answering them now. I think that's the thing that we all share in common, that we are not just excited about the questions, but that we are excited now about the ability to actually start working

on the answers and to push that envelope and to think about how do we figure out if there's life on Europa or in an exoplanet? Or how do we look for Planet 9? Is there another big planet in the outer solar system? Was there life on Mars? Is there life on Mars today? Those questions have been asked for a while, at least some of them. Some of them we didn't know to ask.

We didn't know to ask the question about Planet Nine until relatively recently. We didn't know to ask what an exoplanet atmosphere looked like until relatively recently, especially on the scale of, geez, solar system history is a brand new question. But now we can start answering them. And I think that's the thing that we all share. And I think that's the thing that scientists in general share. It's just the thing that we are so compelled to try to understand is just different. But I think at the end of the day, for all of us, it's just, I just really have to know the answer to this question. Exciting times, Sarah. They are exciting times. I want to say

thank you. You're very welcome. But I also want to take another quick look for the benefit of the radio audience that will only be able to see it in maybe a few more still photos. Yeah. Go back to your lab. Absolutely. Absolutely. We'll go get some pictures. Let's go ahead over there.

Okay. There it is. There's the sort of heart of this lab. Yeah. That's at least the mechanical heart of the lab for sure. I think we have at least a few lovely beating hearts around this joint. But that's certainly the mechanical heart of the lab. So that's the phaser chamber. You put me to shame because, of course, it's the people who bring the heart to the lab.

But yeah, this is it. We'll put a picture of it up, maybe with you in it for scale, so that people can see what we've been talking about. But it's a beautiful piece of hardware. Oh, thank you. it represents a lot of hard work on the on the part of the people that that work in this research group and right now it's running this is my favorite plasma color so we're running a titan experiment right now which as you mentioned before is this beautiful violet color and it's just it always makes me feel a little something deep down inside when i see it running because i know that there's science happening right now and it's it's science that we made happen. All right, now what is this whole panel of stuff that you told me was also

fabricated here? Yeah, so the chamber itself, which is about the size of a two liter bottle, is where all the chemistry and all the interesting stuff happens. But as you'll be able to see in the pictures, I guess, that you'll post, there's this whole apparatus connected to it that is almost entirely to do with making the atmosphere very precisely so all of these valves and tubing and stuff is is to get the right mixture of gases so whatever our gas recipe is and then the final step is getting it to temperature so we're running a titan experiment right now so that means getting it cold so the gases flow through this kind of vat of liquid nitrogen to get them nice and chilly before they flow into the chamber. And so that's really what this whole setup is about, is just making sure that inside of the chamber, inside the phaser chamber,

the conditions are precisely what we want them to be. And then they'll stay stable for the duration of the experiment, which will be three continuous days. And you can simulate the composition, you were telling us earlier, of pretty much any atmosphere that we know about, at least, or maybe some we don't know about. Yeah, I mean, at this point, just because we've been doing so many different experiments, and especially with the exoplanets where we did this big range, we have all of the major atmospheric gases currently in the lab. In fact, they're in a bunch of cylinders behind you right now. So we could do and have been doing Venus, Pluto, Titan, Triton, a bunch of extrasolar planets. We've been contemplating some Saturn experiments recently. So we can basically do whatever atmosphere we want at this point,

which is exciting and also sometimes a little overwhelming. Planetary atmospheres are us. I mean, and looking at this, my two and a half year old grandson would go nuts with all these valves. He would have the best time turning all of these. So one of my favorite things actually, and we don't, it doesn't happen very often, but it's always really exciting when it does happen. And I could let you do it if you want. You know, this whole thing, which looks all very, very complicated, actually, the way the experiment gets turned off and on

is just that little red button right there. And so one of my favorite things to do, and we have a step stool, actually, it's right there, is to have kids come visit the lab, and we'll just let them turn the button off and on a bunch of times. And they're like, oh, look, because it turns the plasma off and on instantaneously, and so they can stand on the little step stoolool and look in there and push the button. Or their sibling will push the button. Or their mom or dad will push the button.

And then they can watch it go off and on. Seriously, he would go nuts. Yeah, I know. Of course, I'm just hiding my own enthusiasm here because I can barely resist. I don't think you're actually hiding it. The cylinder down here that has ice forming on it. Yeah, that's beer brewing equipment. So anybody who does homebrew would very, very much recognize that piece of equipment because we actually bought it from a homebrewing company.

Oh, great. Because it was a much better solution to our problem than we were able to come up with on our own. And so we thought, well, they already make this. And luckily, so far, we haven't had any auditors come by and be like, why are you using grant money to buy beer brewing equipment? For very good reason, as it turns out. For good reason. You can show the photographic evidence that we are, in fact, not brewing beer with it. We are brewing planetary atmospheres in the phaser chamber. Some microbrewery is going to love to hear about this. I mean, I would love if anybody wants to

sponsor us, we would happily take some free homebrew equipment off of your hands to do some science with. Science needs to go where it must. The other thing that is in here, which you said is one of your loves, I looked at it and I thought oh this is just your your typical glove box not not really yeah it's a little weird to describe a piece of equipment as your love but we have a dry nitrogen oxygen-free glove box which is where we remove all of our samples from the experiments and also where we keep them and so in that box they're protected from earth's atmosphere. Any subsequent chemistry it would do, anything it would do to try to ruin all of the work that we've put into it. It was something that I didn't have access to when I was working on experiments as a grad student or as a

postdoc. And so when I got the chance to build my own lab, my very first thought was, I need a glove box. And so as I demonstrated for you earlier, when I show it to people, I tend to give it a little hug because it's just so nice to have it here. And just one less thing that we have to worry about when we're trying to understand what we've done in our experiments. It's also nice if you need a high five or a hug. The arms that are sticking out, which I guess you can take a picture of and show people. So you just come in here and give a little high five. If you're having a hard day, just come give a little hug.

So you just come in here and give a little high five. If you're having a hard day, just come give a little hug. So it's nice to have these little creepy arms kind of sticking out of it. It can be used for good instead of evil if you want to. The reasoning behind this, you've basically said, but it's the same as when we heard Vicki Hamilton on this program talking about why she's so excited about getting that pristine bit of asteroid Bennu because as soon as something touches our nasty oxygen-rich atmosphere, it ain't the same anymore. Yeah, Earth is a really challenging place to try

to study not-Earth things. So as we were mentioning, I would really want to lab on the moon. I mean, this is why. And so instead, I have this glove box. And so it's actually, it's kind of fun too because you can think of it as a reverse spacewalk. So you have to make sure you have everything in there that you need before you start doing stuff. Because once you're set up, you can't, like, open the airlock and let things in. Which it has on the side. There is an airlock for obvious reasons. It has two airlocks.

It has a big airlock and a little airlock. The little airlock, by the way, is for when you forgot something. So then you don't have to pump down the huge airlock before you can open it. Like you're like, oh shoot, I needed that wrench. Darn it. You can pump down the little air lock and just get the wrench in that way. It doesn't take nearly as much time as if you had to do it through the big air lock. But yeah, that's one of my favorite pieces of equipment in this lab for sure. This is one of the reasons I love going to people's labs because they are basically adult playgrounds of science. Yeah, it's definitely for sure.

We have a lot of things that we frequently refer to as toys, although, you know, when something costs more than your house, you don't really want to think about it necessarily as a toy. But I will say, and this is just really cheesy, but maybe everybody already knows that I'm kind of a ball of cheese. I will say, and this is really cheesy, but maybe everybody already knows that I'm kind of a ball of cheese. I mean, there are times when it's quiet. Sometimes if I'm here on the weekend, nobody else is here, and I'll just pop into the lab to grab something. I forgot a pair of scissors. I just need to check on this experiment real quick. And, you know, I'm not sure what triggers the thought in my head, but all of a sudden I just get overwhelmed realizing, like, this is mine.

This exists because I came here and I built it, and I get to decide what we do with it. And that you don't get that with a lot of other things in planetary science. You know, the Mars rover isn't anyone's. It's a team of 500 scientists who are all wanting to do science in different directions with different instruments and whatever else. And so in this one little space in planetary science, I can say, hey, like, let's do this experiment. Or what if we change this thing? And that's really nice. It's exciting. You've earned that pride. Keep up the great work.

Thank you so much. Time for a very special caffeinated edition of What's Up on Planetary Radio. I am joined by the chief scientist of the Planetary Society, Dr. Bruce Betts. And boy, did your question about the ISS coffee maker generate a lot of action. No, nothing makes people more passionate than their source of caffeine. Oh man, you can say that again. I can't wait to get to answering that contest because we've got some really good stuff. But I can wait if you tell me about great stuff in the night sky. I will.

There's like really neat stuff going on with things lining up in the pre-dawn in the east. We've got four planets lined up and I'll even throw in the moon as a bonus. So going from upper right to lower left in the eastern horizon, up pretty high. You got bright Jupiter and then yellowish Saturn and then super bright Venus. And then the challenge, which will be to see Mercury, which is along the line to the lower left of Venus, looking bright but down buried in the light of dawn. It will actually get better over the next week or two,

get a little bit higher in the sky. And then the moon, the moon's going to be moving through this line over the next several days until it's hanging out near Venus on the 2nd of April. It's cool. But wait, don't order yet, Matt. I know you want to, but in the evening sky, we have Mars, which is looking like a bright, but not that bright reddish star, but it's hanging out in an interesting area of the sky. It's near the Pleiades over the next several days. And then it'll be lined up.

So you'll have Aldebaran, a bright reddish star. And then Mars to its right. And this is in the southwest in the evening. I'm sorry, Aldebaran, Mars, and then the Pleiades all lined up, particularly around the 8th of April. And Aldebaran's the brighter of the two right at the moment. That's all great, but I want to go back and compliment you on a turn of phrase, buried in the light of dawn.

It's going to be my epic book that I write. I love it. Speaking of epic, this week in space history, 45 years ago, 1974, we got our first up-close look at Mercury. Mariner attended its first Mercury flyby. Moving on. Random Space Fact. How authoritative. I try.

The Soviets named spacecraft after where they were going. So Mars one, Venera one for Venus. But what about when the spacecraft went two places? The Vegas spacecraft were named V-E-G-A, a contraction of Venera because they were going to Venus and Gali, which for reasons that are unclear to me was how they said Halley for Halley's Comet in Russian. So it was Venera plus Gali. And again, I don't know why the name got translated with a G, but that's where Vega came from. I did not know that until recently. So I thought I would share. I didn't know that until just now. Thank you.

Wow. Knowledge. Knowledge. Knowledge. We move on to the trivia question that got you and our audience so very excited. What is the name of the espresso maker on the International Space Station? How'd we do, Matt? Apparently great. Wow.

Did we ever do great, both in quantity and quality? First, let me, I think I have to eliminate one up front. You're probably not willing to accept fictional coffee makers, are you? No, no. Okay. Well then, very sorry, John Morgan of Anacortes, Washington, who said it was Hal of Hal 9000 fame. International Space Station. It's a different place. Does the red light mean it's done? International Space Station.

It's a different place. Does the red light mean it's done? All right. Here's our actual winner, Eric Fox. First time winner, Boise, Idaho. He loves the show. He says that that coffee maker is called the I.S. Espresso. Yes, indeed. Espresso.

Congratulations, Eric. Nice work. And we did get the correct answer from a tremendous number of people. But it's Eric who is going to be getting a Planetary Society kick asteroid rubber asteroid, along with a 200-point itelescope.net astronomy account, itelescope.net astronomy account, and Michael Walls, Out There, A Scientific Guide to Alien Life, Antimatter, and Human Space Travel, a very great book with Michael's own little hand-drawn cartoons in it. So congratulations, Eric. A whole bunch of people who wanted to salute one of my favorite astronauts, probably because I met her and she was so nice, Samantha Cristoforetti. How appropriate. The Italian astronaut was the first

to drink an espresso while she was wearing a Starfleet uniform. And she get this, she drank it from a special cup, a special capillary action microgravity coffee cup designed by Don Pettit. And isn't that interesting? Because she didn't have to drink it out of a bag. Anyway, she was the first on the ISS to drink the product that came out of that machine. Which makes sense because I believe, and I may be going beyond my knowledge here, that the Italian Space Agency provided espresso. You are absolutely right. They did it in cooperation with a company, Lavazza.

I think that's how it would be in Italian, Lavazza coffee. There were a whole bunch of people, more than I can mention, who pointed out that Samantha was the first to enjoy that first cup of Java made on the ISS. We got this from Brenton Rashid in Australia. He says, talk about your giant leaps for mankind. Kevin Sullivan, this one cracked me up. Kevin Sullivan in Clayton, California. With sunrise every 90 minutes, I would wear this puppy out. Olafransen in Sweden.

So if Canada invented a dessert machine for the ISS, would it be the Canada ice cream maker? Callum. Maybe, maybe. Here's another Australian. Callum in Australia. He's just 10. So he says, I don't drink coffee, but my mom now doesn't want to be an astronaut because she likes a flat white or a latte. She wants milk in her espresso. Well, we'll work on it, Callum.

Once they send a cow to space, we'll be good. How about a barista? Edith Wilson in Gulf, Ontario. She's worked at a whole bunch of coffee shops, she says. She wants to be that first barista on the ISS. Probably have to give a heck of a tip. Yeah, I would think. And the commute to the station and back for the work shift would be very expensive.

Finally, Dave Fairchild, our poet laureate, if you need your coffee while you're up in space today, just turn to the ISS Espresso, which I'm very glad to say was built by the Italians. Their caffeine don't mess around. Just take a sip and soon your feet will float up off the ground. That's it. Thank you, everybody, including all the folks I wish we had had time to read. We're ready for another contest. I feel badly it's not about caffeinated beverages. Maybe next time. Every other week, I think, should be a coffee-related question. All right. On what types of bodies, and I'm going to give you one example, which you

should include, planets, on what types of bodies have we landed spacecraft that have transmitted after landing? So they survived landing, they transmitted. What types of bodies, what categories have we as humans been awesome

and landed on and transmitted? Go to planetary.org slash radio contest. That's great. You have until Wednesday, that's Wednesday, April 3rd at 8am Pacific time to get us this answer. And win yourself a Planetary Society kick asteroid, rubber asteroid, and a 200 point itelescope.net account from itelescope with its worldwide network of scopes that you can use remotely and image things all over the universe. Guess what I just remembered? What did you just remember, Matt? This week's guest. This is so perfect. Sarah Horst, the researcher that we spoke to, people call her all the time and ask, what are the constituents of those materials called tholins that you find here and there around the solar system,

including on Titan, the moon of Saturn? Guess what one of those constituents is? Coffee? Caffeine. Oh. Wake up and smell this Saturnian coffee. Thank you, sir. I think we're done.

All right, everybody. Go out there, look up in the night sky, and think about what you would name your espresso maker or soda machine or just your tap water faucet. Thank you, and good night. That's Bruce Betts, the chief scientist of the Planetary Society, a man who proves that you can live by coffee alone. He joins us every week here for What's Up.

Have you heard about my new Planetary Radio monthly newsletter? It's great fun. You can subscribe for free at planetary.org slash radio. The link is right below the Freeman Dyson video. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its fired-up members. Mary Luz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed

by Peter Schlosser. I'm Matt Kaplan, Ad Astra.