Pod Insights StarTalk Podcast Europa Clipper’s Search for Life with Kevin Hand About this episode Will we find life alive in our very own solar system? Neil deGrasse Tyson dives into the ocean worlds beyond Earth, exploring the Europa Clipper, and the search for life in our own backyard with astrobiologist and planetary scientist Kevin Hand.
Transcript Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
0:01 Neil deGrasse Tyson? Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.
0:15 Neil deGrasse Tyson? This is StarTalk. Neil deGrasse Tyson, your personal astrophysicist. Today, we're going to talk about ocean worlds. And we've got with us a previous guest on StarTalk, Kevin Hand. Kevin, welcome back.
0:30 Speaker 01 Hey, my pleasure, and welcome to JPL.
0:32 Neil deGrasse Tyson? Oh, yeah, this is not my office, is it?
0:35 Speaker 01 You've made a great trip out here.
0:36 Neil deGrasse Tyson? It's not my office.
0:37 Speaker 01 Yeah, yeah, yeah.
0:38 Neil deGrasse Tyson? Ah, yeah, in your turf at Pasadena, California, the Jet Propulsion Labs. I don't ever presume that everyone knows what those three letters stand for, but you can take it for granted if you work here.
0:50 Speaker 01 Right.
0:51 Neil deGrasse Tyson? Everybody knows. I don't think everybody knows. Jet Propulsion Labs and Water Worlds is your thing.
0:58 Speaker 01 It is.
0:59 Neil deGrasse Tyson? And my God, just just at the dawn of COVID, you had a book by that title.
1:03 Speaker 01 That's right, Alien Oceans.
1:05 Neil deGrasse Tyson? Alien Oceans, there it is.
1:06 Speaker 01 Yep.
1:07 Neil deGrasse Tyson? Typically, when people think about an ocean world other than Earth, they go straight to Europa at the top of everybody's list.
1:15 Speaker 01 Yeah.
1:15 Neil deGrasse Tyson? I don't know if it has a better PR agent, or, and so, but if you abstract that idea and go to any place that might have sort of liquid in the world doing anything, that list goes up.
1:29 Speaker 01 It does, absolutely. And the, these ocean worlds, Europa is sort of the the mother of ocean worlds.
1:38 Neil deGrasse Tyson? Yes. Europa, again, a moon of Jupiter.
1:41 Speaker 01 Correct.
1:41 Neil deGrasse Tyson? Mm-hmm.
1:42 Speaker 01 You know, and even back in the, in the late 70s, we could see with the Voyager data that something curious was going on with Europa. And over the course of the past several decades, we've now come to learn and appreciate that the outer solar system has got a small fleet of ice-covered worlds.
2:06 Speaker 01 And beneath their icy shells, these moons of the inner solar system have liquid water oceans. And of course, the big picture for me is the search for life beyond Earth.
2:15 Neil deGrasse Tyson? That's your guiding star.
2:17 Speaker 01 Guiding star. I would love, you know, life on Mars, exoplanets, you know, SETI, et cetera. But these ocean worlds like Europa and Enceladus and Titan, these are worlds where life could be alive to extant life.
2:32 Neil deGrasse Tyson? Oh, because when you're looking at Mars, no one really thinks anything's gonna be crawling around on its surface. Whatever might have been happening billions of years ago. But there's no active water activity on Mars.
2:43 Speaker 01 Well, at least not on the surface. Exactly. Not on the surface. There could be on the subsurface. Who knows? Maybe there's life in the subsurface on Mars. But our search for life on Mars is a search for past life. And the molecules of life don't last long. So like DNA, RNA, proteins, you know, the stuff that makes our biochemistry.
3:04 Neil deGrasse Tyson? But bones last pretty, pretty long.
3:06 Speaker 01 Well, bones do last long, you know, and it's not inconceivable.
3:11 Neil deGrasse Tyson? Don't tell Lucy that we didn't find life. Lucy would beg to differ.
3:16 Speaker 01 Yeah, and as you appreciate, you know, back in the Viking days, even Carl Sagan wanted to leave, put some lights on the Viking landers. So what if there's a Martian mouse, right? So, you know, a Martian mouse would leave bones behind. Bones do last for a long time. But for the most part, we're talking about the search for microbial life. And microbes do actually leave behind minerals.
3:37 Neil deGrasse Tyson? By the way, if a microbe had bones, I don't want to meet it. I don't know what the hell that microbe is doing.
3:44 Speaker 01 Well, some of the most beautiful, you know, if you ever see like travertine or some of the beautiful rock structures that are used.
3:53 Neil deGrasse Tyson? Or the Burgess Shale. Yeah, is that in Canada, I think?
3:56 Speaker 01 Yeah, Burgess Shale has got animals, but you know, there are.
3:59 Neil deGrasse Tyson? Because that was after the Cambrian explosion, if I remember correctly, or during it.
4:03 Speaker 01 In that timeframe.
4:04 Neil deGrasse Tyson? In that time. So they took on very interesting shapes, but they got preserved. That's my point of that.
4:09 Speaker 01 Yeah, exactly. Whereas microbes.
4:12 Speaker 01 Microbes can mediate rock structures. And if we see sort of a weird wavy rock form, sometimes referred to as a microbialite or a stromatolite, that is a form of an inorganic biosignature for microbes. It's kind of like bones for microbes in some ways.
4:31 Neil deGrasse Tyson? I like that analogy.
4:32 Speaker 01 It's more of a frozen apartment building for microbes.
4:34 Neil deGrasse Tyson? And you knew somebody lived there because it's an apartment building?
4:38 Speaker 01 It's an apartment building. But you want to couple that observation of the strange rock structure with some detection of organic compounds or other things. But that's all for Mars, right? Looking at life in the past, billions of years ago on Mars. When it comes to a separate, independent origin of life and a separate tree of life, we're going to be kind of constrained on Mars because those large biomolecules of, you know, if life on Mars utilized DNA, DNA only lasts like maybe 10 million or at best, tens of millions of years in the rock record. So we're not going to get like Martian DNA from samples returned from Mars.
5:22 Speaker 01 On a world like Europa, on a world like Enceladus, these are worlds where if we find indications of life on the surface of the icy shells, that's most likely, I would argue, an indication that life is currently alive in the oceans below. And that's extraordinary because then we can actually study it and see, does it run on DNA, RNA and proteins? Or is there a different ballgame?
5:49 Neil deGrasse Tyson? Mechanism altogether.
5:50 Speaker 01 Yeah, you know, contingent versus convergent.
5:51 Neil deGrasse Tyson? That would completely transform everything we know of biology.
5:53 Speaker 01 Exactly, you know, contingent evolution versus convergent in terms of...
5:57 Neil deGrasse Tyson? What is contingent evolution?
5:59 Speaker 01 The impact that caused the dinosaurs to go extinct is perhaps a somewhat useful, though mildly flawed contingent example. You could say that humans would not be here. If it weren't for the, the impact that wiped out the dinosaurs.
6:17 Neil deGrasse Tyson? That is definitely the case.
6:19 Speaker 01 Well, but you might argue that at some point, something else would have wiped out the dinosaurs. But you get my point.
6:23 Neil deGrasse Tyson? No, it's definitely the case.
6:25 Speaker 01 Yeah.
6:25 Neil deGrasse Tyson? We're working in natural history museum, we got bones everywhere.
6:28 Speaker 01 Yeah.
6:28 Neil deGrasse Tyson? Okay, I'm telling you, here's the argument for that, just hear me out.
6:32 Speaker 01 Yep.
6:32 Neil deGrasse Tyson? If you didn't otherwise know this.
6:33 Speaker 01 Yeah, yeah.
6:34 Neil deGrasse Tyson? Do you know, when T. rex went extinct, 65 million years ago, do you realize more time had elapsed between the extinction of the stegosaurus and T. rex than the extinction of T. rex and today?
6:47 Speaker 01 Yeah.
6:48 Neil deGrasse Tyson? So dinosaurs thrived for hundreds of millions of years. If you say, well, something might have still taken them out in the last 65 million years, I don't think so.
6:56 Speaker 01 No.
6:56 Neil deGrasse Tyson? Because it would have taken out a whole lot of other things and we would have known about it. Dinosaurs were a highly successful phenotype.
7:03 Speaker 01 Yep.
7:04 Neil deGrasse Tyson? Phenotype, is that the right word?
7:05 Speaker 01 Ah.
7:05 Neil deGrasse Tyson? No, but hi- hi- highly successful branch in the tree of life, the collective things we call dinosaurs. So I think they would have been here and we'd still be scurrying underfoot, not trying to get eaten as a snack by whatever the version of T. rex is that survived today.
7:21 Speaker 01 Exactly, so, so I'll remove any nuance, give it, right? And say that that is contingent.
7:27 Neil deGrasse Tyson? Okay.
7:27 Speaker 01 And then convergent is something like eyes.
7:29 Neil deGrasse Tyson? Oh yeah, no, I got convergent, yeah, yeah, that one where a highly useful feature evolves completely independently.
7:35 Speaker 01 Right.
7:36 Neil deGrasse Tyson? And to help, to serve the same purpose.
7:38 Speaker 01 Exactly, so something that I find fascinating is, when it comes to the origin of life, is the polymerization of amino acids or nucleobases, et cetera, is that something that we're gonna find is convergent? So, life on Europa or Enceladus evolved to use DNA also?
7:57 Neil deGrasse Tyson? Is it inevitable?
7:58 Speaker 01 Right, or is there some other way to get that biochemistry done?
8:02 Neil deGrasse Tyson? Now, the best argument I've heard for DNA, although I- It took me part of the way there, but I'm still skeptical because of the complexity of a DNA molecule.
8:12 Speaker 01 Yeah, it's crazy.
8:13 Neil deGrasse Tyson? A geologist said, "Look, when we go to other planets, the geology is familiar."
8:18 Speaker 01 Mm-hmm.
8:19 Neil deGrasse Tyson? Right, a rock crystal of these atoms crystallizes the same way, if given the right temperatures and pressures, here as in there.
8:29 Speaker 01 Right.
8:30 Neil deGrasse Tyson? And so if the geology repeats itself, no matter what planet we're on,
8:36 Speaker 01 Yeah.
8:37 Neil deGrasse Tyson? maybe biology will repeat itself.
8:39 Speaker 01 Exactly.
8:40 Neil deGrasse Tyson? And I thought, "Okay." I threw a bone to that, and I said, "All right, let me hang with that for a bit." But speaking of bones, I got a bone to pick with you. You lumped Titan in with Enceladus and...
8:54 Speaker 01 Europa.
8:55 Neil deGrasse Tyson? And Europa. How dare you?
8:57 Speaker 01 Go on, go on.
8:59 Neil deGrasse Tyson? We... You're motivated by the search for life.
9:03 Speaker 01 That's right.
9:04 Neil deGrasse Tyson? Life on Earth everywhere has needs, uses liquid water.
9:07 Speaker 01 Yep.
9:08 Neil deGrasse Tyson? There's no liquid water on Titan.
9:10 Speaker 01 Well, to be clear, there is. We do think that beneath the ice shell of Titan, there is an ocean trapped beneath that thick ice shell. But I think you're referring to the fact that on the surface, we got these liquid methane and...
9:24 Neil deGrasse Tyson? If you have liquid methane, you don't have liquid water.
9:26 Speaker 01 That's right.
9:27 Neil deGrasse Tyson? Just to be clear about that.
9:28 Speaker 01 Yep.
9:29 Neil deGrasse Tyson? Okay? But it's not just a given that every moon is gonna have a heated interior from tidal forces. Now, I didn't do my homework on Titan before this interview, but is it subject to the same tidal stressing of its physical body as Europa and as Enceladus?
9:46 Speaker 01 It's a bit of a more complicated story, specifically at Saturn, and this is... The story is complicated.
9:52 Neil deGrasse Tyson? Titan, moon of Saturn.
9:53 Speaker 01 Right. So Titan and Enceladus and the moons of Saturn, when it comes to the tides and how much tidal energy they have now and have had in the past.
10:05 Speaker 01 It's a bit complicated because the various moons go through resonances, right? Kids on a swing set, kind of pumping each other up to swing in harmony or out of phase, right? In the Jovian system with
10:17 Neil deGrasse Tyson? Jupiter system.
10:18 Speaker 01 Yeah, the Jupiter system with Io, Europa, and Ganymede. Those three moons are right now in a beautiful resonance. We call it the Laplace resonance. So for every two times Io goes around Europa, Io goes around Jupiter, Europa goes around Jupiter once. For every two times Europa goes around Jupiter, Ganymede goes around Jupiter once.
10:41 Neil deGrasse Tyson? I did not know they were in resonance.
10:43 Speaker 01 Yeah, and so that's what keeps their orbits slightly
10:45 Neil deGrasse Tyson? The system evolves to that because the dynamical forces favor it.
10:49 Speaker 01 Exactly, so gradually the orbits widen out and then Io starts tugging on Europa and Europa on Ganymede. Perhaps someday Callisto will be part of the party, but right now it's not.
11:01 Neil deGrasse Tyson? So that would complete the big four. Io, Europa, Ganymede, Callisto. The four that Galileo discovered.
11:08 Speaker 01 That's right.
11:09 Neil deGrasse Tyson? Yeah, we call them Galilean moons.
11:11 Speaker 01 Yeah.
11:12 Neil deGrasse Tyson? In fact, he called them stars, I think.
11:13 Speaker 01 That's right.
11:14 Neil deGrasse Tyson? The Medicians stars.
11:15 Speaker 01 He was no idiot. He knew where the paycheck was coming from.
11:17 Neil deGrasse Tyson? Because they were just points of light.
11:20 Speaker 01 That's right.
11:21 Neil deGrasse Tyson? That moved around Jupiter and why think it's a moon if it's just a dot of light? It looks like a star.
11:26 Speaker 01 So he started off really well with like naming the stars, the stars of Medici. The Medici family was all happy and he was like, oh no, these things go around Jupiter. Next thing you know, he's under house arrest.
11:53 Speaker 02 I'm Nicholas Costella and I'm a proud supporter of StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.
12:12 Neil deGrasse Tyson? What then, why not call Io an ocean world?
12:17 Speaker 01 Well, let's zoom out and think about kind of a Goldilocks scenario, right? In the early days of astronomy and planetary science, our conceptualization for habitability was kind of framed around this Goldilocks scenario Venus, Earth, and Mars. Venus is too hot, Mars is too cold, Earth is just right, and that's all mediated by the energy that the planets receive from the sun, from the central star.
12:45 Neil deGrasse Tyson? Not just that, the energy that reaches the surface, because you can reflect away some energy and that doesn't participate in the energy equation.
12:53 Speaker 01 And so the thinking back then, and still today, is that in order to have an Earth-like habitable planet, you have to be at that right star/planet distance so as to maintain and sustain liquid water on the surface of your world. Whereas what these ocean worlds of the outer solar system are teaching us is that there's a new Goldilocks in town. It's a Goldilocks where the energy for maintaining and sustaining liquid water comes not through your parent star, but rather through the tug and pull and mechanical deformation and friction and internal heating of tides of getting stretched by Jupiter, which is some 318 times as massive as the Earth.
13:37 Speaker 01 And so back to your question about Io, in this analogy with a new Goldilocks, Io is kind of like Venus. Billions of years ago, Io may have had water, but Io is the most volcanically active body in the solar system, and it has since lost any water that it perhaps had in the early days.
13:56 Neil deGrasse Tyson? Oh, you misunderstood my point.
13:58 Speaker 01 Go on.
14:00 Neil deGrasse Tyson? You misunderstood, no, I didn't make myself clear. Your book is titled Alien Oceans. You're talking about ocean worlds. You didn't specify water ocean.
14:13 Speaker 01 So you want to qualify a magma?
14:15 Neil deGrasse Tyson? A magma ocean on Io.
14:17 Speaker 01 Well, I told you at the beginning.
14:18 Neil deGrasse Tyson? If it's the most volcanically active object known.
14:22 Speaker 01 You find life forms in a magma ocean?
14:25 Neil deGrasse Tyson? I don't know.
14:29 Speaker 01 Fair enough, fair enough.
14:30 Neil deGrasse Tyson? But you're right, if it's hot enough to melt rock,
14:32 Speaker 01 Yeah.
14:33 Neil deGrasse Tyson? probably there's no life hanging out.
14:34 Speaker 01 Yeah.
14:35 Neil deGrasse Tyson? Doing a backstroke.
14:35 Speaker 01 Yeah. But you're, you are correct in that there have been some nice papers on a magma ocean in Iowa. Because that tidal energy dissipation is so extreme.
14:47 Neil deGrasse Tyson? Okay.
14:47 Speaker 01 From an habitability standpoint, it's got a game over.
14:50 Neil deGrasse Tyson? Okay, but also, I wanted to think very freely, because you guys make me do this. If we go to Titan.
14:58 Speaker 01 Yeah.
14:58 Neil deGrasse Tyson? Where it has enough atmospheric pressure to sustain a liquid state of methane. Because as, without pressure, then you lose your liquid, the range of temperatures where you can keep a liquid, right?
15:10 Speaker 01 Right.
15:10 Neil deGrasse Tyson? So, so maybe life does not require liquid water, maybe it just requires a liquid. Can you imagine a life form where it is liquid methane coursing through its veins?
15:20 Speaker 01 Yeah.
15:21 Neil deGrasse Tyson? Or whatever circulatory system it has?
15:23 Speaker 01 Yeah, so I really hope that kind of weird life exists on Titan. The challenge is, I actually have a bit of a hard time formulating an hypothesis that it could exist. So, for example, Europa and Enceladus, we can say-
15:42 Neil deGrasse Tyson? Why should nature care what you have a hard time figuring out?
15:46 Neil deGrasse Tyson? Are you the metric that exists in the universe?
15:49 Speaker 01 You're 100% right.
15:50 Neil deGrasse Tyson? I know you wrote a book on it and everything, I get that, but still.
15:53 Speaker 01 But, but when we do experiments, obviously with a scientific method, you formulate an hypothesis.
15:58 Neil deGrasse Tyson? Yes.
15:58 Speaker 01 And so I can formulate a hypothesis that life on Earth is based on liquid water, a suite of elements, and some energy to power life. I can then look at worlds like Mars and Europa and Enceladus and say, check, check, check. Now, there's a fourth element there of time and stability that we can come back to, and there's some differentiation. But Mars, Europa, and Enceladus, I think we can check the box on, on liquid water and the other keystones for life. With the liquid methane on Titan, it's hard for me to say, like, based on what I know of life on Earth, or even oil fields on Earth, that, that a hydrocarbon liquid could give rise to life.
16:43 Speaker 01 And, and here's a, the sort of key chemical difference. Liquid water is a polar solvent, right? So in liquid water, we can dissolve other polar compounds.
16:57 Neil deGrasse Tyson? The shape of the molecule, right?
16:59 Speaker 01 That's right. It gives a little plus minus.
17:00 Neil deGrasse Tyson? Yeah, it's got hydrogen and oxygen and two hydrogens coming off at an angle there.
17:05 Speaker 01 Yep.
17:06 Neil deGrasse Tyson? Yeah.
17:06 Speaker 01 Yeah, and so we get the electrons get sort of preferentially positioned such that you end up with a plus and a minus with the molecule.
17:12 Neil deGrasse Tyson? So just correct my chemistry if I get it right. So if the two oxygens were sticking straight out on either side, then the molecule itself would have no polarity in that sense, correct? And that is, there would be no difference between one orientation and another? And water would lose all of its really cool properties that we cherish?
17:33 Speaker 01 Well, the positive and negative actually comes a little more from the hydrogen and oxygen differentiation, right?
17:40 Neil deGrasse Tyson? Well, so it's not the angle that they're coming down?
17:43 Speaker 01 The angle plays a little bit, but the...
17:45 Neil deGrasse Tyson? Okay. Thanks for filling in my chemistry.
17:47 Speaker 01 Yeah, if you split it down the middle, like the oxygen is on one side of the V and the hydrogen is on the other. Yeah, and so if you flattened it out, you would definitely affect the charge distribution.
17:59 Neil deGrasse Tyson? Yeah, that's what I thought. And it wouldn't be as effective at things we care about. Yeah.
18:04 Speaker 01 Yeah, and certainly, you know, when it comes to ice, you wouldn't get that beautiful hexagon that's in part due to the V shape of water. I think it's like 109 degrees and then 107, depending on liquid and solid form. But liquid water, great at dissolving other polar compounds.
18:26 Neil deGrasse Tyson? Universal solvent, we call it.
18:27 Speaker 01 Universal solvent for life on Earth, right? But you go to Titan, and now you've got this, these cold by our standards, liquid methane lakes and seas. And liquid methane is non-polar. And so you're talking about life arising and thriving in a non-polar solvent.
18:48 Speaker 01 And that just makes me scratch my head. It's like, could that work? I sure hope it does. I sure hope Mother Nature is...
18:54 Neil deGrasse Tyson? I'm just saying, if you go back 100 and whatever years, and when evolution was first a thing that people discussed, the, in fact Darwin himself might have called for this, is what we need is a 72-degree tide pool. So it's just right for life to form. And then the more we looked, it was like, no, you don't need that. You can do it this way. In fact, you don't even need sunlight. I'm old enough, I'm an old man here. My textbook said life requires sunlight. Alright, that's before we had the undersea vents. Which got a geochemical energy, thermal energy down there. So, and now even in modern astrophysics, planetary astronomy,
19:37 Neil deGrasse Tyson? the Goldilocks zone is insufficient to get it all. All the places where you'd have liquid water. So, this is an exercise in broadening any definition we previously laid down for what we'd expect of life.
19:50 Speaker 01 Yeah. And I think there's one thing, I'd be curious to hear your thoughts on this. Life is just, biology is a layer on top of geology, okay? And as such, what life does is...
20:03 Neil deGrasse Tyson? Wait, wait, just to be clear. We would later learn even that some significant fraction of Earth's biomass lives underground as a participant in the geology that's there. So it's not just life on Earth and then hand over to the geologist. There's this, there's this zone where the two have to make nice in the coffee lounge, right?
20:24 Speaker 01 And so life's job in the universe is to accelerate our production of entropy and heat, abiding by, if you will, the second law of thermodynamics. And so, when it comes to Titan and say weird life on Titan in a non-polar solvent, yeah, I think as long as there is some energy that needs to be dissipated in some way, perhaps biology will fill that energetic niche, even if it requires going way out of the box of what we're able to conceive of.
21:16 Neil deGrasse Tyson? I'm reminded in the movie 2010 where we learn where the life form that made the monolith, monolith came from, from 2001. And do you remember where it came from?
21:28 Speaker 01 Remind me.
21:29 Neil deGrasse Tyson? Is it Europa?
21:30 Speaker 01 Well, but the actual...
21:32 Neil deGrasse Tyson? But that was the solar system's outpost of this life was Europa.
21:37 Speaker 01 That's right.
21:38 Neil deGrasse Tyson? And I think they found chlorophyll on the surface of Europa.
21:41 Speaker 01 Right, so back then, there was the thinking that, in the movie, they show the sort of a green underneath the ice. That would require a very thin ice shell at Europa. So, yeah, that's where the sort of monolith stuff originates, but then it goes back to some distant place.
21:58 Neil deGrasse Tyson? Yeah, of course.
21:58 Speaker 01 Yeah, and 2001, 2010, some of my favorite movies, but I get no ending of people saying, "Attempt no landing on Europa," based on that movie.
22:11 Neil deGrasse Tyson? Are you sure? You don't have to... Are you authorized to divulge where we're not supposed to?
22:16 Speaker 01 In the books.
22:17 Neil deGrasse Tyson? Wait, dude, you're on a mission called Europa Clipper. You're going to Europa, low dipping over Europa, but you're not landing there.
22:25 Speaker 01 That's right, but doing beautiful flybys.
22:27 Neil deGrasse Tyson? But you're not landing there. You're heeding the warnings of the aliens in 2010.
22:33 Speaker 01 No, not at all. There's a cadence to it.
22:35 Neil deGrasse Tyson? That's what you'd have to say, if you did. That's just what you should say.
22:41 Neil deGrasse Tyson? But let's talk about Europa Clipper. A six-year mission there, and...
22:47 Speaker 01 Six years to get there.
22:48 Neil deGrasse Tyson? Yeah, and then you hang out there a bit, orbiting Jupiter, but doing some close flybys of Europa.
22:55 Speaker 01 That's right.
22:56 Neil deGrasse Tyson? And it's very exciting.
22:57 Speaker 01 It's tremendously exciting. And when we say flybys, normally when we think about a spacecraft flying by a world, Thousands of kilometers away. The engineers here at JPL, the pinball wizards are able to get the Clipper spacecraft.
23:14 Neil deGrasse Tyson? But pinball wizards because you have multiple.
23:19 Speaker 01 Gravity of all.
23:20 Neil deGrasse Tyson? Europa Clipper is getting a gravity assist from, from what?
23:24 Speaker 01 From Earth and Mars, and then once it's in the Jovian system.
23:28 Neil deGrasse Tyson? Wait, so this is a two cushioned pool shot to get to.
23:32 Speaker 01 To get to Jupiter.
23:33 Neil deGrasse Tyson? To get to Jupiter then.
23:34 Speaker 01 At Jupiter, then we go off the cushions of Ganymede and Callisto a bit.
23:38 Neil deGrasse Tyson? Oh, so you get more gravity assist from the moons.
23:41 Speaker 01 That's right.
23:42 Neil deGrasse Tyson? Very cool.
23:43 Speaker 01 By that time, it's gravity assist to, to slow us down.
23:46 Neil deGrasse Tyson? Yeah, because people forget that you can gravity assist in either way for your energetics.
23:51 Speaker 01 Yeah.
23:52 Neil deGrasse Tyson? Yeah.
23:52 Speaker 01 And so Ganymede and Callisto, it's a beautiful thing about the Jovian system, the Jupiter system, where those larger moons can actually help out the spacecraft engineers to get into all sorts of different orbits. And so we'll pinball around.
24:06 Neil deGrasse Tyson? Pinball wizards. Yes, great title for them. Wait, are they okay with the title?
24:10 Speaker 01 I use this endearingly with my engineering colleagues all the time, and they like it.
24:14 Neil deGrasse Tyson? They like it. Okay.
24:15 Speaker 01 And so we pinball around Jupiter, and then we start going into these roughly 14 day petals orbiting Jupiter and making these close flybys of Europa.
24:29 Neil deGrasse Tyson? Like petals of a flower.
24:30 Speaker 01 Petals of a flower, exactly. Or think about like, you know, those Spirograph.
24:34 Neil deGrasse Tyson? I've had one, yeah.
24:35 Speaker 01 Yeah. And so we'll orbit Jupiter, but make these flybys of Europa, and the close approaches.
24:41 Neil deGrasse Tyson? How close are you gonna get?
24:43 Speaker 01 25 kilometers is the closest ones.
24:45 Neil deGrasse Tyson? That's as close as any object has ever swung by anything.
24:50 Speaker 01 It's, it's gonna be extraordinary. And, and the images, half a meter per pixel.
24:55 Neil deGrasse Tyson? What?
24:56 Speaker 01 Yeah. And the Galileo images. So think about how extraordinary the, the images.
25:01 Neil deGrasse Tyson? Galileo the spacecraft?
25:02 Speaker 01 Yeah.
25:02 Neil deGrasse Tyson? Okay, because he was.
25:03 Speaker 01 Not the astronomer.
25:04 Neil deGrasse Tyson? And he did have a telescope, and he did look at Jupiter.
25:06 Speaker 01 So make sure we're on the right.
25:10 Neil deGrasse Tyson? Galileo did not have half a meter per pixel resolution.
25:13 Speaker 01 So, so Galileo the astronomer.
25:16 Neil deGrasse Tyson? Yes.
25:16 Speaker 01 Point of light. Galileo the spacecraft. We get beautiful pictures at, you know, kilometer scale.
25:22 Neil deGrasse Tyson? Suppose you could just tell Galileo what you're about to do. What a privilege that would be.
25:29 Speaker 01 Oh, absolutely. I mean, and that's 400 years ago, 400 plus years.
25:34 Neil deGrasse Tyson? That's not even, that's nothing.
25:35 Speaker 01 That's nothing.
25:36 Neil deGrasse Tyson? In the history of our species.
25:37 Speaker 01 Yeah.
25:38 Neil deGrasse Tyson? Just say, you know, one day we're gonna go there.
25:40 Speaker 01 Yeah.
25:41 Neil deGrasse Tyson? One of your Medellinians.
25:46 Neil deGrasse Tyson? So you're gonna, a close view of the surface ice.
25:51 Speaker 01 Yeah.
25:52 Neil deGrasse Tyson? But you're not looking at the water below, and that's what you really care about.
25:55 Speaker 01 Right. And so what Clipper has onboard are cameras to give us pictures of the surface, spectrometers to tell us about the surface composition. And by looking at the surface ice, we know from Galileo spacecraft, from telescopes, that...
26:14 Neil deGrasse Tyson? And Hubble helps out.
26:15 Speaker 01 And Hubble, yeah. And that the ice of Europa serves as a window into the ocean below. So using the spectrometers and looking at the ice, we will get a bit of a fingerprint of the ocean chemistry.
26:27 Neil deGrasse Tyson? But that's only because there are cracks that might fill in with the water and then refreeze.
26:32 Speaker 01 That's right. And subduction, subsumption.
26:35 Neil deGrasse Tyson? What is subsumption?
26:36 Speaker 01 Uh, it's...
26:38 Neil deGrasse Tyson? That shouldn't even be a word. Just my opinion here. Subsumption?
26:42 Speaker 01 Yeah, it's a term coined by some colleagues of mine.
26:46 Neil deGrasse Tyson? Oh, you all just made up the word?
26:48 Speaker 01 As we do.
26:50 Neil deGrasse Tyson? Because I know there's subduction.
26:51 Speaker 01 Right.
26:51 Neil deGrasse Tyson? As when a continental plate goes under.
26:54 Speaker 01 That's right.
26:54 Neil deGrasse Tyson? And then there's...
26:55 Speaker 01 Yeah, and so...
26:56 Neil deGrasse Tyson? Give me some other words here.
26:57 Speaker 01 Is kind of thinking about how that might occur on an icy shell. So for the most part, you can think about subsumption as subduction, but on an icy world, with perhaps some other things mixed in.
27:09 Neil deGrasse Tyson? Did it really need another word?
27:10 Speaker 01 Yeah, debatable. But so with Clipper, we've got these cameras and spectrometers, and then mass spectrometers.
27:22 Speaker 01 That will allow us to taste any plume material coming out of Europa. What we can, we can taste any organic compounds, carbon compounds.
27:32 Neil deGrasse Tyson? So taste, you mean almost literally taste because if you have the molecules and you have something to detect the molecule, you've basically tasted the molecule.
27:40 Speaker 01 That's right. Exactly. And, and so I'm a I'm a co-investigator on the Suda instrument, which is a dust analyzer, mass spectrometer, uh, surface analyzer for dust, uh, at Europa.
27:52 Neil deGrasse Tyson? Okay.
27:53 Speaker 01 Acronyms these days are.
27:55 Neil deGrasse Tyson? Okay. I'll give you that. I'll give you a hall pass on that one.
28:00 Speaker 01 They don't necessarily give away the first letter of the word anymore.
28:02 Neil deGrasse Tyson? Okay. So that's more of a passive experiment because you have, you're not, you're not aiming for those. It has to sort of come to you.
28:10 Speaker 01 Yeah.
28:10 Neil deGrasse Tyson? If it happens to be spewed forth from the surface.
28:14 Speaker 01 Exactly. Think about a kid with a bucket running through a snowstorm. Um, uh, it's much more muted than that at Europa, but we will be getting those compounds into our bucket and passing them through the mass spectrometer.
28:26 Neil deGrasse Tyson? And these aren't big plumes like you find on Enceladus, but there is certainly upward movement.
28:31 Speaker 01 Yeah. So I've been on, uh, a team that's used the Hubble Space Telescope and the James Webb Space Telescope to look for plumes on Europa.
28:39 Neil deGrasse Tyson? Isn't it great? We have telescopes that can see the edge of the universe and then right in front of our nose as well. This is, this is, this is, we got good people.
28:48 Speaker 01 We can get amazing things done when we set our minds to it.
28:51 Neil deGrasse Tyson? Our people are good folks. Not just the astronomers, but of course the engineers that actually make it happen. Shout out to the engineer here. Okay.
28:58 Speaker 01 They get the hard stuff done. Um, so Enceladus is a tiny moon. It's only 500 kilometers in diameter and very low gravity. And so plumes on Enceladus go out for hundreds of kilometers. Europa is about the size of our moon and Europa's gravity is about one seventh
29:14 Neil deGrasse Tyson? So Europa is way bigger.
29:16 Speaker 01 Way bigger. 3,000 kilometers.
29:18 Neil deGrasse Tyson? I didn't even think, think about that.
29:19 Speaker 01 Yeah. And so.
29:20 Neil deGrasse Tyson? So 500 kilometers in American speak, that's like
29:23 Speaker 01 300 miles.
29:24 Neil deGrasse Tyson? 300 miles across.
29:25 Speaker 01 Yeah.
29:25 Neil deGrasse Tyson? All right. It's still a nice object, but it's not like, it's not like Europa.
29:29 Speaker 01 Right. And, uh,
29:30 Neil deGrasse Tyson? So what are the chances of you seeing sort of macroscopic life that might have? bubbled up and landed on the surface like fishes flopping.
29:37 Speaker 01 You asking if our bucket's gonna catch a squid?
29:42 Neil deGrasse Tyson? And you reminded me, you advised on the movie, the sci-fi movie, low budget, but still carefully conceived and executed movie, The Europa Report.
29:51 Speaker 01 That's correct, yep.
29:52 Neil deGrasse Tyson? And I have a tiny cameo in that.
29:55 Speaker 01 You do?
29:55 Neil deGrasse Tyson? Tiny little cameo. I think it was on CNN, they used actual footage of me on actual news. Commenting, I said, "I wanna go, I's fishing on Europa. Cut a hole, lower submersible and see what's there."
30:10 Speaker 01 Yep.
30:10 Neil deGrasse Tyson? And that was expressing my enthusiasm for this.
30:13 Speaker 01 You and I, that's, if we could fish on Europa.
30:16 Neil deGrasse Tyson? Oh, man. So you were an advisor to that film?
30:18 Speaker 01 That's right. And they did a fantastic job.
30:20 Neil deGrasse Tyson? That's why it was so good. Not because I was in it, but because they thought about the science.
30:26 Speaker 01 Well, one of the really cool things, you know, I've done some consulting on various movies and I was like, "Hey, team, if we're gonna do Europa, we gotta do Europa right." And so they didn't know that much about the radiation environment of Europa.
30:37 Neil deGrasse Tyson? From Jupiter.
30:38 Speaker 01 From Jupiter, exactly. And so that's factored into the movie and becomes sort of central to the story. And on Europa, that irradiation of the surface would kill an astronaut. But coming back to habitability, one of the things that we're looking for with Europa Clipper is how some of the radiation-driven chemistry on the surface of Europa could positively affect the chemistry of the ocean and the habitability of the ocean. Let me give you an example. Sulfur comes from volcanoes on Io. The eruptions on Io exude sulfur and some of that sulfur actually lands on Europa.
31:20 Neil deGrasse Tyson? This is sulfur that has been spewed forth from volcanoes faster than the escape velocity of Io.
31:26 Speaker 01 That's right.
31:26 Neil deGrasse Tyson? Thereby contributing to the general orbital environment of Jupiter.
31:30 Speaker 01 That's right. It gets spun up in Jupiter's magnetic field. Next thing you know, that sulfur ion is slamming.
31:37 Neil deGrasse Tyson? Well, it's an ion, so it responds to the very strong magnetic field.
31:40 Speaker 01 That's right. But then, so some of that sulfur impacts Europa and then gets radiolytically processed into sulfate and other forms of sulfur, which then, if mixed into the ocean.
31:54 Neil deGrasse Tyson? Sulfate.
31:54 Speaker 01 Sulfate. Microbes on Earth love sulfate. And then get this, so what happens when you split apart H2O, water? You get OH and H. Some of that H escapes to space, some of the OH recombines with another OH, forming H2O2. H2O2 is hydrogen peroxide. We have observed-
32:17 Neil deGrasse Tyson? Which is the same thing as what anyone would call peroxide.
32:20 Speaker 01 Exactly.
32:20 Neil deGrasse Tyson? In the pharmacy.
32:21 Speaker 01 In the pharmacy, yes. Yeah, and so-
32:23 Neil deGrasse Tyson? That's that old joke. You know the old joke?
32:25 Speaker 01 No, what's that?
32:26 Neil deGrasse Tyson? Someone goes to the bar and says, "I'd like some H2O." And then they hand him a glass of water. And then someone sees that and says, "I want some H2O2."
32:35 Speaker 01 And so they go get a glass of-
32:37 Neil deGrasse Tyson? And then they drink it.
32:40 Neil deGrasse Tyson? That'd be a very chemically literate bartender.
32:43 Speaker 01 Right, right. Not a very tasty drink. But so, get this. That radiation processing of the ice, of the H2, of the water ice on Europa, leads to the formation of hydrogen peroxide, H2O2, which then that also gets radiolithically processed or decays to O2, oxygen. And, telescopically, we see hydrogen peroxide and oxygen in the surface ice of Europa.
33:09 Neil deGrasse Tyson? You have to be very clever to go from one step to the other to see this through. A game of dominoes, and you don't know where the dominoes are, but you think you do, and maybe it is. And if it is, this leads to that, leads to that, and then you have what you need.
33:23 Speaker 01 Right. Except, we actually observe it. So, to be clear, we see condensed phase oxygen on the surface of Europa.
33:28 Neil deGrasse Tyson? And you think that's how you get it.
33:30 Speaker 01 Right. We get it radiolithically. I do that in my lab and-
33:32 Neil deGrasse Tyson? There it is. I love when you say that. "I do it in my lab." "Need some of that? I get it in my lab."
33:39 Speaker 01 And that's the fun of like lab and spacecraft.
33:41 Neil deGrasse Tyson? I know, it's great. It's great. And they go hand in hand.
33:43 Speaker 01 Right. Yeah, and so we can make predictions and it's a lot of fun. But so, of course, we know that oxygen's very useful for life on Earth, not just for microbes, but for-
33:52 Neil deGrasse Tyson? Well, for our kind of life.
33:53 Speaker 01 For macrofauna.
33:53 Neil deGrasse Tyson? Anaerobic life does not like oxygen, just to be clear.
33:57 Speaker 01 And they love sulfur and methane, all sorts of other things. But so, here you are, the radiation environment on the surface of Europa could produce compounds, which then, if delivered to the ocean through subduction, subsumption, whatever you want to use, could help provide rich chemistry to the ocean to sustain a biosphere within Europa's ocean.
34:19 Neil deGrasse Tyson? And this will give you some of the chemical gradient you have described that you need.
34:22 Speaker 01 So you got hydrothermal vents on the bottom of the ocean, spewing out things like methane and hydrogen and sulfide. And then from the ice shell, you might have things like oxygen and sulfate. So you can connect the battery, the biochemical.
34:38 Neil deGrasse Tyson? And that's how you make Godzilla.
34:41 Speaker 01 At least.
34:42 Neil deGrasse Tyson? This is the recipe for Godzilla. So we got to wrap this up. Just one point, I care a lot about words and what they mean and how they're received.
34:53 Neil deGrasse Tyson? Europa has water underneath ice.
34:57 Neil deGrasse Tyson? You named this mission Europa Clipper. And a clipper ship from the 19th century floats on water.
35:05 Speaker 01 Right.
35:05 Neil deGrasse Tyson? Swiftly. So who came up with the word clipper?
35:10 Speaker 01 I don't know.
35:11 Neil deGrasse Tyson? Cause that's, that's a little, you're not floating anywhere.
35:13 Speaker 01 Right, yeah, yeah.
35:14 Neil deGrasse Tyson? You're still.
35:15 Speaker 01 So they're, they're, in the early days, remember that during the gold rush, clipper ships were used to very quickly get people from New York City to San Francisco.
35:26 Neil deGrasse Tyson? Yeah, they're some of the fastest ships made. They're narrow, were a lot of sails, the wind can take it, before steamships, of course.
35:32 Speaker 01 That's right.
35:32 Neil deGrasse Tyson? Right.
35:33 Speaker 01 And so.
35:33 Neil deGrasse Tyson? By the way, I think the phrase, let's get there on a good clip.
35:36 Speaker 01 Yeah.
35:36 Neil deGrasse Tyson? I think that comes from clipper ships.
35:37 Speaker 01 Yeah.
35:38 Neil deGrasse Tyson? Yeah, clip is swiftly.
35:39 Speaker 01 Yeah.
35:40 Neil deGrasse Tyson? A clipper ship gets you there fast.
35:42 Speaker 01 Yeah.
35:42 Neil deGrasse Tyson? So, so I know you're getting there fast because you stripped down the Falcon Heavy. The Falcon Heavy doesn't even have return stages because that, that uses weight that you could put in your payload. Right. So you strip it down, put it all in the payload, get it out there as fast as you can, get your two, get your two gravity assists, you're there in six years.
36:00 Speaker 01 That's right.
36:01 Neil deGrasse Tyson? So in that sense, it was a clipper, but not in the sense that it's floating anywhere. I just got to make, I got to get that off my chest.
36:05 Speaker 01 100%, yeah. And some of that, that clipper terminology goes back to variation and launch vehicles and stuff.
36:11 Neil deGrasse Tyson? Okay, all right. Well, Kevin, great to have you back.
36:14 Speaker 01 Thanks so much, Neil, my pleasure and great to see you and it's an exciting time.
36:19 Neil deGrasse Tyson? So if something bad or good happens to the clipper mission, we got to get you back on.
36:22 Speaker 01 Oh, God.
36:22 Neil deGrasse Tyson? To talk about it. Okay.
36:24 Speaker 01 Laugh or cry.
36:25 Neil deGrasse Tyson? When all the good things happen.
36:27 Speaker 01 Yeah.
36:27 Neil deGrasse Tyson? We got to get you back on. We, we won't do it while you're busily receiving the data, but when, if there's a break in there, you got to come back on.
36:35 Speaker 01 Anytime.
36:35 Neil deGrasse Tyson? And we can find your book, Alien Oceans.
36:37 Speaker 01 Alien Oceans.
36:38 Neil deGrasse Tyson? I love the assonance there, Alien Oceans.
36:40 Speaker 01 The Search for Life in the Depths of Space.
36:41 Neil deGrasse Tyson? Yes, there you go. All right, good luck with that.
36:43 Speaker 01 Thanks so much.
36:44 Neil deGrasse Tyson? For sure. This has been StarTalk, our JPL edition. Oh, yeah. Neil deGrasse Tyson, bidding you, as always, as they do here. To keep looking up.
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