StarTalk Radio - Enceladus Up Close, with Carolyn Porco - StarTalk All-Stars

Episode Date: September 6, 2016

Is the subsurface ocean on Saturn’s moon Enceladus the most likely place in our solar system to harbor life? Dive in with StarTalk All-Stars host and planetary scientist Carolyn Porco, guest NASA astrobiologist Chris McKay, and co-host Chuck Nice. Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

This is StarTalk. Hello, this is StarTalk All-Stars Edition. I'm your All-Star host this evening. Carolyn Porco is my name. And I'm a planetary scientist and the leader of the imaging science team on the Cassini mission, which is as we speak, in orbit around Saturn. My co-host today is Chuck Nice. Thank you, Chuck, for being here. Thank you. And my guest today is Chris McKay from the Ames

Research Center in the Bay Area. He's an astrobiologist extraordinaire. Chris spends his time scouring the deserts of Earth from Antarctica to Siberia, Namibia, Sahara, trying to understand those places on the Earth that might be like Mars in their environment and wondering how life can thrive there. He's been involved in conjuring what kind of human mission back to Mars might be like. This is a mission that would be piloted by humans. He's involved in that. And I've invited him here today because he is my cohort for the last 11 years in trying to get people to pay attention to what we have found with the Cassini mission on Enceladus, which is a small moon in the Saturn system, no bigger across than England, and why this small moon presents to us the most promising environment in the solar system to actually search for life or evidence of prebiotic chemistry.

So welcome, Chris. Thank you, Carolyn. It's a pleasure to be here talking with you. Yes. So we've gathered your cosmic queries about Enceladus and astrobiology from various social media. That's right, Chuck. Yes, that's exactly what we have done. And we have questions via Facebook and Twitter and you name it, whether it's StarTalk.net. It doesn't make a difference. We take them. And they all want to know about Enceladus and more, you know, astrobiology and more.

You know, people see your name and, you know, some people just want to know about Enceladus and more, you know, astrobiology and more, you know, people see your name and, you know, some people just want to know about Cassini and some people want to know about Saturn. And so I know that we're kind of focused on Enceladus, but, you know, when you say, when people who follow us, when we say Carolyn Porco, they immediately think Saturn because Neil calls you Madam Saturn. I'm Madam Saturn. For the rest of my Saturn because Neil calls you Madam Saturn. I'm Madam Saturn. For the rest of my life, I'll be Madam Saturn. It's all right.

It could be worse. It could be a lot worse. It could be worse. So let's take our first, you know, we always like to have a Patreon. For those of you who are interested in supporting us on Patreon, by doing so, you get to do cool things. Like you get invited to parties that we might throw, or you can submit a question for our Cosmic Queries, and we will make sure that we read it, because you gave us money.

That's a basic transaction in life. Right? That's a basic life transaction. You gave us money, and now we're going to do something for you. So, this is from Luna McIntyre, who says, Do you think there are parallels that can be inferred by whatever is found with the Europa mission? Since the liquid oceans on both moons, I suppose both moons, she means Enceladus and Europa, seems to be due to tidal heating. So are there any, first of all, is that the case?

I mean, are both moons, are there oceans created by tidal heating? And are there any parallels that we can draw or infer from the similarities between Europa and Enceladus? There are a tremendous amount of parallels that we can draw. They are, in fact, both heated by this mechanism of tidal flexure, which is why they have oceans within them and both of them have oceans. oceans within them, and both of them have oceans. And I would say it goes the other way, that we have been nearly a dozen years now exploring up close and personal Enceladus with the Cassini mission, and with an amazing suite of 12 investigations on the orbiter that have been brought to bear over the course of those dozen years. And we know a tremendous amount about Enceladus, really far more knowledge about Enceladus at this point in time than we do about Europa. But I'll turn this over to Chris, because Chris also has a lot to say about this topic.

So what do you have to say? Well, to me, the most interesting comparison between Enceladus and Europa would be comparing the type of life we might find in both of them. Imagine sometime in the future when we find life on Enceladus, we find life on Europa. Are they the same life? Do they represent a common origin or did life start independently on both of these water worlds or did life start on one and not the other? So I'm always focused on the biology questions, and a comparison between worlds is the most interesting possibility in terms of what kind of questions we can ask about biology and compare these two water worlds.

And then, of course, we'd want to compare them to Earth as well. How does the biology on Europa, if there is any, and the biology on Enceladus, if there is any, compare to the biology we have here on Earth. That's the ultimate question for astrobiology. Yeah. And let me just remind people why we've gone so goo-goo-ga-ga over Enceladus. And that is because we found that it has 101 tall geysers

that are erupting from its south polar terrain, which is an area, if you were to scale Enceladus up to the size of the Earth, it would be like the latitude of Tierra del Fuego and everything south. Wow. Or if you were biased towards the northern hemisphere, it would be like Edinburgh, Scotland, and everything north. Wow. So imagine having 101 enormous geysers erupting from the terrain that's that large.

And once we found with Cassini these geysers, and we knew that the particles that we see in our images were accompanied by vapor, and they formed this enormous plume that went ultimately tens of thousands of kilometers into orbit around Saturn. We took Cassini and we went barreling through it. We went barreling through it time and time and time again. And we've been able to collect material and measure the contents of the vapor, measure the contents of the particles, measure the characteristics of the particles, how big they are, how their size is distributed above the surface.

And all this information has finally told us where we are right now. We know we have a global ocean under about 35 kilometers worth of ice. It's salty. It's salty like the Earth's ocean is salty. And it has organic materials. So it's got all the formal requirements of what in the NASA world, the NASA universe, we call a habitable zone. And that ocean is accessible now. again with the proper instruments, better than we have on Cassini, to measure it with a greater precision and start asking really interesting astrobiological questions. Chris, what are some

of the things we could do if we had a mission that went back to Enceladus with proper instrumentation? What kinds of questions do we really want to know? I think you said it well, Carolyn. We already know it's habitable. We already know it has organic material. We already know it has liquid water. We know that that liquid water is habitable. So the follow-on questions really go right to the biology. Does this habitable environment, is it inhabited? Does it have life? And then the challenge is, how do we search for life? Well, we can search for life using molecules and tools that we develop for characterizing Earth life. But it'd be nice to also have a capability to detect life if it's not Earth life. So then the question becomes, how do we detect life that's similar to Earth,

lives in water, made of carbon, but is not directly related to us doesn't have our dna and i think the answer to that is to search for amino acids and search for their handedness and see if there is a enrichment of heavy complex amino acids in the plume of and then to see if those amino acids all have the same handedness, which is a clear signature of biological selectivity. So when you, you know, from an astrobiological standpoint, what would be more desirable? To analyze these things or analyze these components flying through these plumes or capturing the water and bringing it back? Good question. That's a very, very good question. There are people out there, groups of people, one group I know of that are looking at the possibility of a sample return.

It's not a trivial thing to do because there's a lot of concern if you bring a sample back to Earth. You don't want to have an Andromeda strain scenario where you contaminate the Earth. So, you know, that has to be done carefully. Those Earthlings were really something special until they bought back that old Enceladus water. Really? That was the beginning of the end. You know, the instruments that we have on Earth are far more sophisticated than the ones that we could carry on a spacecraft. So Chris, in fact, has been a big proponent of a sample return mission. Yeah. But as Carolyn points out, one has to be extremely careful in bringing back a sample from an environment that we think could have life in it. And that environment

is very similar to Earth's oceans. We've never done that before. We've brought back samples before, but we've never brought back a sample from a habitable environment. So this is a new challenge, and we have to proceed extremely carefully with it. So I think realistically, the next missions to Enceladus will not be sample return. They will investigate the plume in situ following up on Cassini, but they will be designed to search for life, unlike Cassini. Cassini did a fabulous job. It was a wonderful and unexpected find, and its ability to investigate it surprised all of us. And what it told us also surprised all of us. investigated surprised all of us. And what it told us also surprised all of us. Now we're back with a mission that's based on what we know and search for life in the plume. And then, meanwhile,

think about how we bring a sample back safely, because ultimately we have to do that. Yeah, I wanted, can I just make a plug for Cassini? Because as Chris said, the instruments on Cassini that were really, I mean, the cameras, you know, can take a picture of anything. But the instruments that told us about the chemistry were not designed to investigate a plume of material that was as tenuous as that which is coming off the south pole of Enceladus. They were designed to measure the atmosphere of Titan, for example, which is much more hefty. So it was a beautiful demonstration of how important it is to, first of all, be in orbit and kind of take up residence in a planetary system so you have the leisure of discovering something

and then going back to investigate it again and again and making changes in your approach. Right. And that's what we did with Cassini. But I want to add just one more thing about Enceladus, which fascinates me. 92, 94% of the stuff that's being erupted from the South Pole of Enceladus, the particles, not the vapor, but the particles, comes back down to the surface. It snows back down to the surface. but the particles comes back down to the surface.

It snows back down to the surface. So if there are microbes in the ocean of Enceladus that are being, you know, shot out, it's snowing microbes at the south pole of Enceladus. So I think another thing we want to do is we want to go sample those particles and see if there are microbes in it. That's what I get really excited about. That's pretty cool. It doesn't get any cooler than that. Yeah, that's like, that's a holy excited about. That's pretty cool. It doesn't get any cooler than that. That's a holy grail.

That's pretty fun. And what do you do when you do that? Is that putting instrumentation down on the surface? Well, this is very interesting. We've all been discussing this. We're discussing how you might actually do this. And it just occurred to me recently, you don't need to land on the surface. Okay. All you need to land on the surface.

All you need to do is really get into orbit around Enceladus. And the speed with which you pick up these particles would be gentle enough that you would not destroy microbes that were in the ice particles. And that's what we want. We'd love to be able to take a look at them. Now, whether or not we have the instrumentation now to do it is a question. Maybe, Chris, do you know something about this, the capabilities of microscopic imagers to do this sort of thing? As you point out, we don't have a heritage in planetary missions of searching for life. We haven't done that since Viking, 1976. But meanwhile, NASA and other organizations have been developing technologies for studying life on Earth. There's been satellites in Earth orbit that have looked at biology. There's technologies on the space station.

And these life sciences technologies can be applied to the search for life and be made suitable for planetary missions. Life sciences technology? Yeah. What do you mean by life sciences? That sounds oddly like a life coach. No, no, not that. What I mean is. Not a lifestyle coach.

Not a lifestyle. What is the life sciences? Go ahead. Well, we can think of two different jobs that we might do in space. One is take life from earth right and study it in space that's called life sciences okay search for life on other worlds life detection they're both centered on life but in one case you're taking life with you and studying it the other case you're going somewhere and seeing if there's life there but

for example a fluorescent microscope would be handy in both cases. Well, there's not been the development of such a microscope for planetary, but there has been for life sciences. People have taken these kind of instrumentation into orbit to study organisms that they've carried with them to investigate the response of these organisms to the space environment. You can take that technology and repurpose it to searching for life in the plume of themselves. Oh, God, that's so it's so exciting. I can barely stand it. That is really it's like there it's waiting for us to go back. Super cool.

Super cool. OK, let's go on to another question. We have a little bit of time left in our segment. So let's let's grab another question from Nicole coming to us from Twitter at Cape Girl is her name. And she's talking with respect to astrobiology. What role, if any, would the study of planetary atmospheres and remote sensing have on the search for extraterrestrial life? So is there anything that we can glean just from looking at a planet that we know I'll go one step further and say even the planet's landscape from the standpoint of astrobiology and find out about life or extraterrestrial life on that planet. Okay. So I think, Chris, this is one for you did you did you get that yep i got it and this is a really good question it's a really good question and it has implications right now

on searching for life uh on other worlds and other stars exoplanets and also searching for life on titan which is a world that does have an atmosphere, and we can characterize it. And the thought is that life does affect the planet and its atmosphere. The oxygen in our atmosphere is clearly produced by biology. If we see oxygen in the atmosphere of an exoplanet, I would take that as pretty compelling evidence that there is life on that planet making that oxygen. We can apply that same logic.

We can't apply that logic to Enceladus. It doesn't have an atmosphere, nor does Europa. But Titan does. It's a very different atmosphere than Earth's. It would have very different life. But we can take the same logic. If there was life on Titan, how would it change the atmosphere? And the conclusion seems to be it would be depleting hydrogen. So imagine a mission that goes to Titan and searches for a

depletion of hydrogen and uses that as a biosignature, the same way that the presence of oxygen in an atmosphere is used as a biosignature. Okay, Chris, we have to, we have to, sorry, we have to take a short break now. We'll come back to what you're saying because it's really exciting. And we'll take more of the Cosmic Queries from our audience when StarTalk returns. Welcome back to StarTalk Radio, All Stars Edition. I'm your all-star host, Carolyn Porco. And joining me in the studio is Chuck Nice. Yes.

Thank you for being here. Such a pleasure. You're a delight, Carolyn. Well, thank you. And our special guest is Chris McKay, planetary scientist and astrobiologist extraordinaire at NASA. And he was in the middle of giving us an argument about what you might look at on a planet or a moon that had an atmosphere. And how that would determine life. And you were talking about if you were to look at an atmosphere and see oxygen, you would know or you would be able to strongly indicate that, hey, something created that. Something biological created that. So can you go on from there?

Well, the point was, this is a very powerful technique because it can be done remotely. And the questioner indicated that. And this is true. This is the only way we could detect life currently around planets, around other stars. There's some question. Now, I would just be maybe the devil's advocate here and say that you could never really know to 100% confidence that that kind of a biosignature would give you,

would mean life, but it would be a strong indicator, I think. That's right. Yeah. It would certainly be very exciting to be an Earth-like planet around a Sun-like star and find high level of oxygen in the atmosphere of that planet. Technically, there's other ways,

but it would be a strong indication of life. Yeah, I know people in that community who think that the only way you'd really know if we had life would be the interception of a signal from an extraterrestrial intelligence. That's like the only thing that would really give you 100% confidence. But it would be a red-letter day if we found an exoplanet with...

Oh, that's fantastic. Well, Nicole, thank you for such a very well-thought-out question. Let us move on and ask a question from Doug Dunphy, who wants to know, what's the next likely mission to Enceladus? And what do you hope it is capable to do beyond Cassini? Hashtag CQ Enceladus, which is our hashtag. I don't know why I read that. Well, you're just being... I'm just being thorough. You're being thorough. Right. A little too thorough. I think we just said that, but we can say it again.

Yes, we did kind of get into that, but go ahead. I was just going to say, Cassini has done a bang-up job unexpectedly because, as one of us, Chris, said, I think we didn't really—we suspected Enceladus might have geysers, of geysers, but we didn't expect that they would look the way they do and be as vigorous a phenomenon as it has been. It's just been an explorer's dream come true. And so what we want to do next is go back with instrumentation that is far better than that which was carried by Cassini, look at the chemical constituents to a finer level of detail and look at abundances of compounds, look at, as Chris mentioned, the handedness of compounds,

because, you know, earthly life prefers a particular type of molecule to another. And if we see that same kind of signature on another planet, that might also indicate a process like life that has singled that particular type of molecule out. So those are the kinds of things we would look for. And like I said, one of my favorites is actually to grab and look at and image microbes. So that's the kind of things that we're talking about going back to Enceladus. Nice. But the key is we are going back. Is that the key? Oh, no, nothing. What? What do you mean? Why would you say that? Well, there's a bunch of us that are really pressing for it, and we have the opportunity.

We now can submit to NASA what are called New Frontiers proposals. So this is proposals for like a big chunk of money, something like $850 million. But that doesn't mean we'll get selected. There are people who want to go to Venus, people who want to go return a sample from a comet. There's lots of competition. Let me ask you this. I mean, this is just part of our conversation.

I think it's terrible that we have to kind of make choices like this. These Sophie's choices where, you know, it's like, well, should we go to Venus or should we go to Mars or should we go back? And it's like we should be doing all of this, to be honest. I mean, let's let's be let's be very square. We should be doing all of this. So how do you prioritize which missions should take place and when? Is there a particular protocol that should be in place to determine maybe this mission is important, but it's more important if we go now? Maybe this mission is important, but it really won't be important until 2030.

important until 2030. So how do you go about making the case for getting these limited funds, which shouldn't be limited as far as I'm concerned? Well, they are limited. And Chris, I'll let you deal with this. You're the guy who works at NASA. Sure, sure. But I'll tell you my way of prioritizing these, because I have to prioritize my time also. What do I work on? All the planets are interesting. I prioritize it based on what's going to tell us the most about biology now. And I think the clear winner is Enceladus. So I would answer, are we going to Enceladus? Yes, because it's clearly the place where we can learn the most about possibility of life right now. Other worlds are interesting too, but Enceladus is ready for investigation.

There's samples there, as Carolyn said, it's a habitable environment. Samples come out in the space. It's the low hanging fruit. It's what we ought to do first, in my opinion. Yeah, it's not clear it's going to happen, but Chris and I, that's why we're cohorts in this together. We're trying to keep Enceladus up front and center

in the minds of people because it is, like you said, we're ready. We're ready now. We know enough to go back and do the job right. Good stuff. Let's move on and take another question. This one a little bit more broad from Kabir Malhotra. Carolyn, you will know the more you do this. People like to, and Chris, you will know because I'm sure you will return as a guest.

People send me their names. You have no idea how to pronounce it. And I butcher their names like you can't believe. And I think that they're doing it on purpose now. I really do. I think people are just sending me made up names. Just to see you. To see me squirm and struggle.

And because, but anyway. At least they're listening. This is true. Okay. Exactly. So this is, I hope I'm saying it. Kabir Malhotra. Malhotra. Okay. Exactly. So this is, I hope I'm saying, Kabir Malhotra. Malhotra.

Okay. Assuming the universe is infinite. That's a big assumption right there. I mean, is the universe infinite? Because I really don't think it is. But anyway, let's not, I'm not answering these questions. You are. How long will it take to produce an exact copy of Earth?

I don't think he means exact copy of Earth, but an Earth-like planet, just, you know, basically our Earth. So an exact copy is ridiculous because, you know, that's ridiculous to say an exact copy of Earth. That's just never going to happen. And by the way, the Earth is changing all the time. So what would that exact copy is ridiculous because, you know, that's ridiculous to say an exact copy of Earth. That's just never going to happen. And by the way, the Earth is changing all the time.

So what would that exact copy be? Right. You know, because the Earth that we live on today is not the Earth that was here four million years ago. That's right. It's a completely different planet now. So, but how long would it take to produce an Earth planet? Well, I'm going to turn this around because that's very difficult to answer.

So I'm going to turn it around to something that's possible to answer. I like the way you work. The Kepler results of how many exoplanets there are and what characteristics they are, this is Kepler with follow-on Earth-based observations

from telescopes like Keck, have indicated something like 25 percent. I hope I get this right. Twenty-five percent of the planetary candidates that they find in the habitable zone of their star are Earth-sized. Okay? Oh, okay. I think that's right. And then some fraction of those would be earth-like and you could call it you know earth twin earth's twin right um and i don't know someone took a reasonable

guess maybe let's say 20 you know it's common nothing on our planet is is unusual that's that's what we've been able to glean about the universe is, you know, what we have here is probably lots of other places. So, 25% of the planetary candidates in their habitable zone are like Earth-sized. Let's say 20% of those are Earth-like, which means like the Earth, okay, the copy. And when you go through all the numbers, the last time I heard this, which was probably six months or a year ago, the number came out to something like 5 billion, billion earth-like planets in our galaxy oh my that's right now here right now right chris do i got that right the gist of the argument is certainly correct there are going to be in our own galaxy a lot of earth-like planets we just

got to look uh we know that there's lots of planets out there and some of them are going to be like earth. We don't need an infinite universe. Our own galaxy, in fact, our own stellar neighborhood probably has lots and lots and lots of earth-like planets, arbitrarily closely similar to earth. The more we want to look, the more we can find ones that are as close to earth as we want it to be. Really? We might have a lot of community work ahead of us. Yeah. Wow. So, I mean, that's pretty unnerving when you think about it because now—

Unnerving, it's like— It's just— It's incredibly exciting. It is exciting. When I say unnerving, I mean in a— In a good sense. In a good sense. It is really that exciting that it's unnerving.

It's shocking is what it is. It's shocking. So now let me ask the both of you this. With that in mind, does it necessarily increase the likelihood of there being intelligent life on one of those planets since we pretty much developed on this planet? Does it increase the likelihood or does it not? I mean, are those two things related in any way scientifically? Well, look, we have a statistic of one. We know on an Earth-like planet, one civilization has developed to the point where we call ourselves intelligent and we are capable of communicating across space. So, you know,

if it happened once, it's likely to happen again. How likely is it? I don't know. I guess that's a guess, but I'm an optimist. I think that probably it's happened many times. Chris, do you want to take a guess? What do you think? You're an optimist, I know. I am as well. And I think it's useful to divide the question into two steps. One is the distribution of life. And then secondly, the distribution of intelligent life.

Certainly, we think that life should be widespread. Whether some of those life forms develop intelligence is a more deeper question. But I tend to be an optimist too. So I think we're going to find the universe is full of life and that many, but not all of those life-bearing planets have developed intelligence. Gotcha. That doesn't mean that they're like on their way to get us right now. It's the distances are, I mean, are prohibitive. You know, when you say a star is 12,000 light years away, we're talking the time it takes light.

Right. The fastest thing we have to get here. It would take us far, far longer than that. So, yeah. So, I mean, realistically, life could exist there, but our being able to get to that life is very unlikely. Well, eventually, I suppose we could put some robotic spacecraft on a course for some star and maybe. That makes sense. Yeah.

So that brings me to another question from both of you. Okay. Especially you, Chris, being an astrobiologist. Is it more important to have a first contact from one of us making contact with intelligent life or from an emissary that we have created, i.e. a robot or Android or some representation of human life, whether it's a computer or what have you. And, you know, of course, that probably will make more sense because we can send that thing out and just let it go. We don't have to feed it. We don't have to worry about it dying and it's not going to bitch and complain like I'm lonely and I miss my family. And so, yeah.

So, I mean, is that is that most likely how we're going to make our first contact uh you know we might have made a first contact already you know i mean we have our uh our signals uh sent out what did dan wertheimer just say he said uh 70 years ago. Right. Something like that. But, you know, so we won't know. That's the thing about this whole thing. The distances are so huge. We won't know if we've made a contact with another civilization until we hear back from them. Gotcha.

Okay. Interesting. Yes. Okay. So we have just limited time. So we're going to wrap this up for this segment. We'll take a short break. And when we come back, we're going to entertain more of our listeners' cosmic queries when StarTalk returns. again and welcome back to Star Talk Radio All-Stars Edition. I am your All-Star host, Carolyn Porco, and joining me in the studio is my fabulous, wonderful, dynamic co-host, Chuck Nice. Thank you. Thank you. The moment I started to look around to see who else was here.

And we have as our special guest, we have Chris McKay, who's an astrobiologist from NASA Ames Research Center in the Bay Area. We've been talking about the search for life in the solar system. There isn't a topic that's more exciting than that. And we're going to now discuss what kind of life we might find in a place like Enceladus and how might it be different than the life we have here on Earth. This is a really tantalizing question because I think most people would agree it would really be far more interesting to find life that was entirely different from the life we have here biochemically, metabolically, all those things, because then we'd have a point of comparison that we could make. And that would give us insights into how life developed one way on one planet and one way on the other. So Chris, why don't you weigh in on this for us? Because I'm

sure this is something that you've thought quite a lot of. Sure. Normally, when we talk about different life, we're thinking something exotic like maybe silicon-based life or something. That's not what we're going to find on Enceladus. Enceladus is a world with water and carbon. Life there will be based on carbon, just like us. But it might still be profoundly different. How that carbon and water arranges to form biochemistry could be very different on Enceladus. So for example, DNA, which we use to store information, may not be the same molecule used on Enceladus to store information. The proteins on Enceladus may be made out of amino acids just like the proteins on Earth, but they may be made out of different amino acids. Or the chirality, the handedness

of those amino acids might be opposite. So there's many ways that life on Saladus could be very, very different than life on Earth. And it would be very interesting to do that comparison. Now, for us to do that, I'm guessing that that's going to be pretty hard to do with the kind of stuff we're talking about that might be done on the very next mission to Enceladus. I'm going to guess that in order to do that, we really got to bring samples back to Earth. Do you agree with that? Not necessarily. Go ahead. I think we could go a long way with instruments that we send there. If, for example, we search for amino acids and we find that the plume of Enceladus has amino acids, complex ones, and they're all, let's say, right-handed, the opposite of Earth-like, then we've learned an enormous amount about life on Enceladus and we've determined that there's life there and it's a separate life from Earth-like.

on its own, and we've determined that there's life there, and it's a separate life from Earth life. Okay, so you're talking about the chirality or handedness, but what about the way its proteins are structured or the way the amino acids go together? That's really higher order stuff. That's hard to do without bringing a sample back. Don't you agree? Sure. We won't answer all of our questions. We won't answer all of our questions.

We won't answer all of our questions, but we'll answer them. Sounds like you've got some life form there crawling around. We won't answer. He wants to go. We won't answer all of our questions. And more complex questions will require more complex instrumentation. But we will be able to answer some questions. And if there is life there, we have a good chance of determining that it's there and determining that it's alien from Earth life. So we could, in principle, go pretty far down the logic tree. Now, eventually, yes, we do want to bring a sample back to Earth. Eventually, the level of sophistication we'd like to apply to investigating a different type of life is the state of the art. And to do that, you need to bring the sample back. But we can make a lot

of progress on the next mission if we send the right instance. Okay, so let me, you know, this is our last segment, and I just wanted to open it up even more, if I could, Chuck. Go ahead. Please, please. In the Saturn system, there's another tantalizing place, which is Titan. Titan is considered kind of, believe it or not, we used to think of Venus as the sister planet to Earth. But Titan is even more like Earth in many respects than Venus is. in many respects, than Venus is. It has landforms that are like we have here on Earth because it's got a substance in its atmosphere, methane,

which acts like water does here on Earth. And it rains out of the sky. It can form clouds. It can carve channels and gullies and so on. It can pond on the surface. And, in fact, it's doing that. In the polar regions of Titan, we have found seas of liquid methane laced with ethane. So, I mean, think of, you know, Lake Michigan brimming with paint thinner or something like that.

You know, that's not too far off in the future. We keep going the way we're going right now. far off in the future. We keep going the way we're going right now. So, you know, now I'm not a fan of thinking that we have life in the seas of Titan because, or at least, excuse me, I should say that we have a chance of really recognizing it because it would be so different than we have here on Earth because we know about earthly life. But I know Chris is a big fan of this idea, so I wanted to give Chris the opportunity to elaborate on the possibility that we could have life in Titan seas, given that the temperature there is so cold and the kinetics are going to be so slow and so on. And then how we might go about even recognizing life in the Titan seas.

Well, that's a really good question. And it roots to what do we think life needs? It's clear that life needs a liquid. On Earth, that liquid is water. The only other liquid that's widespread in the solar system is the liquid methane and ethane on Titan. So could life use that liquid? Now, it's very different than water.

But that doesn't mean that a bit of life couldn't use it, but it would be so different. We wouldn't really know how to recognize it. And that's where we would, the effect that life has on its atmosphere. As we talked about earlier, if there's life on tight, it might be consuming hydrogen and we might be able to detect that atmospheric effect more readily than we could actually detect the life form because we don't even know what kind of molecules to search for. Right. It certainly doesn't use amino acids. Yeah, right.

It doesn't use amino acids. So it's going to be significantly different. It's just a challenge in the space program. It's a challenge to, you know, like I said, this is where the rubber meets the road. You have to design an experiment. You have to know what you're going to measure. And when you're looking at an environment that's alien to the earth and life that may not even be constructed like the earth, that is no common biochemicals, it becomes very challenging. Yes. That was fascinating. That was great stuff. Great stuff. I mean, I'm still fascinated by just the fact of life living in a methane ocean.

That alone is kind of mind-boggling. Yeah. Well, you know, they say, was it Rudyard Kipling that said travel is mind-expanding? Well, you know, planetary exploration is mind-blowing. There you go. All right, let's take a question. Pardon me. I'm terribly sorry. Drew Davenport. And Drew Davenport is writing from Wilmette, Illinois, here on planet Earth. He actually put it that way.

Oh, that's good. We want him. Planet Earth. He actually put it that way. Oh, that's good. Have you ever found anything that you couldn't identify or thought was really strange during a spectral analysis? This is for both of you, actually, because I'm sure that spectral analysis is part of both your missions. Oh, major, major. Is there anything that comes back where you're just like, my, that's odd? Well, I'm not a spectral analyzer myself, but I remember in the early days of the Cassini mission when we were looking at the results of one of the spectrometers on board Cassini that had scooped up material in the plume. And there were some signatures that they couldn't make sense of. And I think at first, in fact, they made a tentative identification,

which did not turn out to be correct. And it turned out to be salt. They had not thought that there would be salt. And when they went back and said, okay, maybe this is salt. And they went back and did the match. It was a great match. So that's my be salt. And when they went back and said, okay, maybe this is salt, and they went back and did the match, it was a great match. So that's my little anecdote. Chris, you must have one.

I can't think of something offhand, but along the lines, I remember when we were first going to Titan, we thought it had a global ocean. When we got there, it didn't. So we were often surprised. I think we have to keep that in mind. Our guesses of what's out there are often wrong. The only way to know is to go look. They're kind of our, if not our bodies, our minds and our emotions are on these robotic spacecraft that we send across the solar system. And, you know, they find things that are, you know, we say, oh, my God, that's so surprising.

We felt that way about the Enceladus plume. We felt that way about the distribution of the hydrocarbons on Titan. We all felt that way about Pluto. When New Horizons got to Pluto. Oh, my goodness, look at this. These regions where you have ice convection and these polygonal features, it's not so much that it's a failure of knowledge. It's a failure of imagination. We understand physics pretty well and chemistry. We understand what happens at various regimes, physical regimes, but it's just that we don't spend an infinite amount of time imagining all the various permutations we might find there.

And when we get there, we end up being surprised. Like, take the Enceladus geysers. We knew post-Voyager, this was after the Voyager mission a couple of years later, a paper was written about the possibility that we could have water geysers on Enceladus. It was suggested that these geysers, they might not have been called geysers, but they would be producing particles that would go into orbit around Saturn to produce the E-ring in which Enceladus is centrally embedded. So that was the connection. So we had geysers on the brain when we went back to Enceladus with Cassini, and we even, the imaging team, planned observations to look for them. And the first image that we have of a plume coming off Enceladus has the word plume in the title of

the observation. It was deliberately planned to search for plumes. Right. So we knew what we possibly might find, but nobody took the time to imagine, well, okay, so we have geysers coming off Enceladus. The gravity on Enceladus is only 100th of the gravity here on the earth. So these things are going to be enormous. No one thought that. So we get there and we see this incredible spectacle. And it just reminded me of this, that, you know, we always fail to imagine what we might find. And it's what makes it so thrilling, you know, just seeing something for the first time. It's just, it's mind-blowing. That's pretty cool. Of course it's cool. Just, it's mind-blowing. That's pretty cool.

Of course it's cool. Excellent, excellent, excellent stuff. All right, let's, actually, Theron, actually, actually, Theron, and coming to us on Twitter at Astro Theron, not to be confused with Charlize Theron. Maybe that's a fan of Charlize. Says, asks this. I really don't understand this question at all, so you guys don't have to help me. Given similar environmental challenges, i.e. liquids behave the same, is it possible for exobiology to produce a species similar to us? We have only about a minute. So you're saying given similar biology?

Is that the similar chemistry? Yeah, similar environmental. Yes. Should we expect something similar to us? Yes. In other words, are we more likely to find something similar to us given the similar situations or environmental situations? Or should we be using our imagination to look for what you just said?

Okay, well, so using your imagination for every permutation would take quite a bit of time. I think this is a question that really devolves to this. What in the evolution of life, to this. What in the evolution of life, what role was played by basic physics and chemical laws, and what was played by serendipity? What was, you know, a meteor hit the earth and destroyed the first experiment, just wiped out all life that was just getting started, and then giving something else the opportunity to evolve? Like, you know, the dinosaurs being wiped out open up the way for us. So we only have seven, six seconds. We're going to have to wind down now. Chris and Chuck, thank you for helping us out today.

It's a pleasure. You've been listening to StarTalk Radio All-Stars Edition. I've been your All-Star host, Carolyn Porco. Until next time. This is StarTalk.