Europa Clipper’s Search for Life with Kevin Hand

Summary

StarTalk Radio: Europa Clipper’s Search for Life with Kevin Hand

Host: Neil deGrasse Tyson
Guest: Kevin Hand
Episode Release Date: October 29, 2024
Podcast Description: Science, pop culture, and comedy collide on StarTalk Radio! Neil deGrasse Tyson, astrophysicist and Director of New York's Hayden Planetarium, and his comic co-hosts, guest celebrities, and scientific experts explore astronomy, physics, and everything else there is to know about life in the universe. New episodes premiere Tuesdays. Keep Looking Up!

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1. Introduction to Ocean Worlds

The episode kicks off with Neil deGrasse Tyson welcoming Kevin Hand back to StarTalk, highlighting Hand's expertise in ocean worlds. Kevin Hand emphasizes the significance of Europa in the study of extraterrestrial oceans.

Quote:
Kevin Hand [03:22]: "And of course, the big picture for me is the search for life Beyond Earth."

Hand describes Europa as the "mother of ocean worlds," underscoring its pivotal role in the exploration of potential life beyond our planet.

2. Comparing Ocean Worlds with Mars

The conversation transitions to comparing Europa and other ocean worlds with Mars. Hand asserts that while Mars is a target for discovering past life, ocean worlds like Europa, Enceladus, and Titan offer environments where life could exist today.

Quote:
Kevin Hand [03:38]: "These are worlds where life could be alive today, extantly."

He points out that Mars primarily represents a search for ancient microbial life due to the lack of active surface water, contrasting it with the subsurface oceans of moons like Europa where extant life might thrive.

3. Biosignatures and Detecting Life

Hand delves into how scientists identify signs of life, focusing on biosignatures such as stromatolites—microscopic structures created by microbial life.

Quote:
Kevin Hand [05:44]: "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."

He explains that detecting both structural formations and organic molecules is crucial for confirming the presence of life, highlighting the methods used to identify such signs on other celestial bodies.

4. Life in Ice Worlds vs. Mars

The discussion explores why ocean worlds are more promising than Mars for finding current life. Hand clarifies that while Mars may harbor past life, the active subsurface oceans of Europa and Enceladus provide more favorable conditions for life to exist today.

Quote:
Kevin Hand [04:10]: "Our search for life on Mars is a search for past life."

He contrasts this with the potential for ongoing biological activity in Europa’s ocean, making it a prime candidate for the search for extraterrestrial life.

5. Chemistry of Habitability

A significant portion of the conversation centers on the chemistry that makes a world habitable. Hand elaborates on the importance of liquid water as a polar solvent, essential for life as we know it.

Quote:
Kevin Hand [20:40]: "Liquid water is a polar solvent."

He discusses the challenges of alternative solvents, such as methane on Titan, explaining why water's unique properties make it indispensable for supporting life’s biochemical processes.

6. Contingent vs. Convergent Evolution

Hand introduces the concepts of contingent and convergent evolution in the context of extraterrestrial life, pondering whether life on other moons would follow similar evolutionary paths as on Earth.

Quote:
Kevin Hand [06:59]: "Exactly. You know, contingent evolution versus convergent."

He speculates on the likelihood of life on Europa either developing similar biochemistry to Earth or taking a completely different evolutionary route, which would revolutionize our understanding of biology.

7. The Europa Clipper Mission

Neil and Hand provide an in-depth overview of the Europa Clipper mission, detailing its objectives, trajectory, and the sophisticated instruments onboard designed to study Europa’s surface and subsurface ocean.

Quote:
Kevin Hand [31:21]: "Europa Clipper has on board cameras to give us pictures of the surface, spectrometers to tell us about the surface composition."

Hand explains that the mission will perform multiple flybys of Europa, capturing high-resolution images and analyzing chemical compositions to assess the moon's habitability.

8. Potential Findings and Implications for Biology

The discussion shifts to the potential scientific breakthroughs the Europa Clipper mission could achieve, particularly in understanding the chemical environment of Europa’s ocean and its ability to support life.

Quote:
Kevin Hand [23:46]: "Life's job in the universe is to accelerate our production of entropy and heat..."

He elaborates on how studying Europa's chemistry could reveal the energy gradients necessary for sustaining life, drawing parallels to Earth's biosphere.

9. Chemical Signatures on Europa

Hand discusses the impact of Jupiter’s radiation on Europa's surface ice, leading to the formation of compounds like hydrogen peroxide and oxygen, which are potential indicators of biochemistry that could support life.

Quote:
Kevin Hand [37:20]: "Radiation processing of the ice... leads to the formation of hydrogen peroxide."

He explains how these chemically processed compounds could be transported to Europa’s ocean, providing the necessary ingredients for a habitable environment.

---

Concluding Remarks

The episode wraps up with an enthusiastic outlook on the Europa Clipper mission. Hand expresses optimism about the mission's potential to uncover signs of life and advance our understanding of ocean worlds.

Quote:
Kevin Hand [42:07]: "Alien oceans search for life in the depths of space."

Neil deGrasse Tyson encourages listeners to stay tuned for future updates from the mission, emphasizing the excitement and importance of these scientific endeavors.

---

Key Takeaways:

• Europa as a Prime Ocean World: Europa stands out among ocean worlds due to its subsurface ocean, making it a prime target in the search for extraterrestrial life.

• Habitability Factors: Liquid water, chemical gradients, and energy sources are essential for supporting life. Europa offers a conducive environment with its liquid water beneath an icy shell.

• Europa Clipper Mission: This mission is pivotal in studying Europa’s surface and ocean chemistry, employing advanced instruments to detect potential biosignatures.

• Chemical Evidence of Life: The presence of compounds like hydrogen peroxide and oxygen on Europa’s surface ice suggests active chemistry that could support life beneath the ice.

• Broader Implications: Discovering life on Europa would have profound implications for our understanding of biology and the potential for life elsewhere in the universe.

---

Notable Quotes:

• Kevin Hand [03:22]: "And of course, the big picture for me is the search for life Beyond Earth."

• Kevin Hand [03:38]: "These are worlds where life could be alive today, extantly."

• Kevin Hand [20:40]: "Liquid water is a polar solvent."

• Kevin Hand [31:21]: "Europa Clipper has on board cameras to give us pictures of the surface, spectrometers to tell us about the surface composition."

• Kevin Hand [37:20]: "Radiation processing of the ice... leads to the formation of hydrogen peroxide."

• Kevin Hand [42:07]: "Alien oceans search for life in the depths of space."

---

Conclusion:

In this enlightening episode of StarTalk Radio, Neil deGrasse Tyson and Kevin Hand explore the depths of Europa's potential to harbor life. From the intricate chemistry that makes Europa's ocean a candidate for life to the ambitious goals of the Europa Clipper mission, listeners gain a comprehensive understanding of why Europa remains at the forefront of astrobiological research. The conversation not only highlights the scientific challenges and techniques involved but also inspires a sense of wonder about the possibilities that lie beneath the icy surface of one of Jupiter’s most intriguing moons.

Transcript

[Neil DeGrasse Tyson]

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[Kevin Hand]

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Again, that's alienware.com deals. Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk, Neil DeGrasse Tyson, your personal astrophysicist. Today we're going to talk about Ocean World and we got with us a previous guest on StarTalk, Kevin Hand. Kevin, welcome back.

[Kevin Hand]

Hey, my pleasure. And welcome to jpl.

[Narrator]

Oh yeah, this is not my office, is it?

[Kevin Hand]

You made a great trip out of here.

[Narrator]

It's not my office. Yeah, yeah, yeah, 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. Everybody knows. I don't think everybody knows. Jet Propulsion Labs and Water Worlds is your thing.

[Kevin Hand]

It is.

[Narrator]

And my gosh, just at the dawn of COVID you had a book by that title.

[Kevin Hand]

That's right. Alien Oceans.

[Narrator]

Alien Oceans. There it is. Typically when people think about an ocean world other than Earth, they go straight to Europa at the top of everybody's list. I don't know if it has a better PR agent, 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.

[Kevin Hand]

It does, Absolutely. And these ocean worlds, Europa is sort of the mother of ocean worlds.

[Narrator]

Europa again, a moon of Jupiter. Correct.

[Kevin Hand]

And even back 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. And beneath their icy shells, these moons of the outer solar system have liquid water oceans. And of course, the big picture for me is the search for life Beyond Earth.

[Narrator]

That's your guiding star?

[Kevin Hand]

Guiding star. I would love life on Mars. Exoplanets, seti, et cetera. But these ocean worlds like Europ and Enceladus and Titan. These are worlds where life could be alive today, extantly.

[Narrator]

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. Well, at least not on the surface.

[Kevin Hand]

Exactly. Not on the surface. There could be in 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.

[Narrator]

But bones last pretty long.

[Kevin Hand]

Well, bones do last long, you know, and it's not interesting.

[Narrator]

Don't tell Lucy that we didn't find life. Lucy would have beg to differ.

[Kevin Hand]

And as you appreciate, you know, back in the Viking days, even Carl Sagan wanted to leave. Put some lights on the Viking lander. 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.

[Narrator]

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.

[Kevin Hand]

Well, some of the most beautiful. You know, if you ever see, like, travertine or some of the beautiful rock.

[Narrator]

Structures that are used, or The Burgess Shale. Yeah. Is that in Canada? I think. Yeah.

[Kevin Hand]

Burgess Shale has got animals, but there are.

[Narrator]

Because that was after the Cambrian explosion, if I remember correctly. Or during it.

[Kevin Hand]

In that timeframe.

[Narrator]

In that time. So they took on very interesting shapes, but they got preserved. That's my point of that.

[Kevin Hand]

Yeah, exactly. Whereas microbes. Microbes can mediate rock structures. And if we see sort of a weird, wavy rock form. Sometimes referred to as a microbial light or a stromatolite. That is a form of an inorganic biosignature for microbes. Kind of like bones for microbes in some ways.

[Narrator]

Oh, I like that.

[Kevin Hand]

It's more of a frozen apartment building for microbes.

[Narrator]

And you knew somebody lived there because it's an apartment building.

[Kevin Hand]

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 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 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 de DNA, RNA and proteins, or is there a different ballgame mechanism altogether? Yeah, you know, contingent evolution.

[Narrator]

That would completely transform everything we know of biology.

[Kevin Hand]

Exactly. You know, contingent evolution versus convergent. In terms of what is contingent evolution, 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 impact that wiped out the dinosaurs.

[Narrator]

That's definitely the case.

[Kevin Hand]

Well, but you might argue that at some point something else would have wiped out the dinosaurs. But you get my point.

[Narrator]

It's contingent. It's definitely the case. I work at a natural history museum. We got bones everywhere. Okay, I'm telling you, here's the argument for that. Just hear me out. If you didn't otherwise know this, 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? So dinosaurs thrived for hundreds of millions of years. Totally. If you say, well, something might have still taken them out in the last 65 million years, I don't think so, 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. Phenotype, is that the right word? No. Highly successful branch in the tree of life, the collective things we call dinosaurs. So I think they, if 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.

[Kevin Hand]

Exactly. So I'll remove any nuance given, right, and say that that is contingent.

[Narrator]

Okay.

[Kevin Hand]

And then convergent is something like eyes.

[Narrator]

Oh, yeah, no, I got convergent. Yeah, yeah, that one. Where a highly useful feature evolves completely independently and to serve the same purpose.

[Kevin Hand]

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 going to find is convergent? So life on Europa or Enceladus evolved to use DNA also.

[Narrator]

Is it inevitable?

[Kevin Hand]

Right. Or is there some other way to get that biochemistry done?

[Narrator]

Now, the best argument I've heard for DNA, although it took me part of the way there, but I'm still skeptical because of the complexity of a DNA molecule. It's crazy. A geologist said, look, when we go to other planets, the geology is familiar. A rock crystal of these atoms crystallizes the same way if given the right temperatures and pressures here as in there. And so if the geology repeats itself, no matter what planet we're on, maybe biology will repeat itself.

[Kevin Hand]

Exactly.

[Narrator]

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 Europa. And Europa. How dare you.

[Kevin Hand]

Go on, go on.

[Narrator]

You're motivated by the search for life.

[Kevin Hand]

That's right.

[Narrator]

Life on Earth everywhere has needs, uses liquid water.

[Kevin Hand]

Yep.

[Narrator]

There's no liquid water on Titan.

[Kevin Hand]

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 liquid.

[Narrator]

If you have liquid methane, you don't have liquid water.

[Kevin Hand]

That's right.

[Narrator]

Just to be clear about that. Okay. But it's not just a given that every moon is going to 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?

[Kevin Hand]

It's a bit of a more complicated story, specifically at Saturn. And the story is complicated.

[Narrator]

Titan, moon of Saturn. Yes.

[Kevin Hand]

Right. So Titan and Enceladus and the moon of Saturn. When it comes to the tides and how much tidal energy they have now and have had in the past, 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 Jupiter system, the Jupiter system with IO, Europa and Ganymede. Those three moons are right now in a beautiful resonance we call 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.

[Narrator]

I did not know they were in resonance.

[Kevin Hand]

Yeah, and so that's what keeps their orbits.

[Narrator]

So the system evolves to that because the dynamical forces favor it.

[Kevin Hand]

Exactly. So gradually the orbits widen out and. 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.

[Narrator]

So that would complete the big four IO, Europa, Ganymede, Ganymede and Callisto. The four that Galileo discovered.

[Kevin Hand]

That's right.

[Narrator]

Yeah. They call them Galilean moons. In fact, he called them stars. I think. That's right, the Medicean stars.

[Kevin Hand]

He was no idiot. He knew where the paycheck was coming.

[Narrator]

From because they were just points of light that moved around Jupiter. And why think it's a moon if it's just a dot of light? It looked like a star.

[Kevin Hand]

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.

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[Kevin Hand]

Supporter of StarTalk on Patreon.

[Narrator]

This is StarTalk with Neil DeGrasse Tyson. What then? Why not call IO an ocean world?

[Kevin Hand]

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 their central star.

[Narrator]

Just that, the energy that reaches the surface because you can reflect away some energy and that doesn't participate in the energy equation.

[Kevin Hand]

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 types tides of getting stretched by Jupiter, which is some 318 times as massive as the Earth. 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.

[Narrator]

Oh, you misunderstood my point. Go on, you misunderstood. No, I didn't make myself clear. Your book is titled Alien Oceans.

[Kevin Hand]

Yeah.

[Narrator]

You're talking about ocean worlds. You didn't specify water ocean.

[Kevin Hand]

So you want to qualify a magma.

[Narrator]

Magma ocean on IO Well, I told.

[Kevin Hand]

You at the beginning it was the.

[Narrator]

Most volcanically active object known.

[Kevin Hand]

You find life forms in a magma ocean. That's.

[Narrator]

I don't know.

[Kevin Hand]

Fair enough, fair enough.

[Narrator]

But you're right. If it's hot enough to melt rock, probably there's no life hanging out doing a backstroke.

[Kevin Hand]

But you are correct in that there have been some nice papers on a magma ocean in IO because that tidal energy dissipation is so extreme. Okay. From a habitability standpoint, it's got a game over.

[Narrator]

Okay. But also, I wanted to think very freely, because you guys make me do this. If we go to Titan, where it has enough atmospheric pressure to sustain a liquid state of methane, because without pressure, then you lose your liquid, the range of temperatures where you can keep a liquid. Right? 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 or whatever circulatory system it has?

[Kevin Hand]

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.

[Narrator]

Can say, why should nature care? What you have a hard time figuring out? Are you the metric of what exists in the universe?

[Kevin Hand]

You're 100%.

[Narrator]

I know you wrote a book on it and everything. I get that. But still.

[Kevin Hand]

But when we do experiments, obviously with a scientific method, you formulate an hypothesis.

[Narrator]

Yes.

[Kevin Hand]

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, 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, Enceladus, I think we can check the box on liquid water and the other keystones for life with the liquid methane on Titan, it's hard for me to say based on what I know of life on Earth or even oil fields on Earth that a hydrocarbon liquid could give rise to life. And here's the sort of key chemical difference. Liquid water is a polar solvent. So in liquid water we can dissolve other polar compounds.

[Narrator]

That's the shape of the molecule, right?

[Kevin Hand]

That's right. It gives a little plus minus.

[Narrator]

Yeah. It's got hydrogen and oxygen and two hydrogens coming off at an angle there.

[Kevin Hand]

Yep.

[Narrator]

Yeah, yeah.

[Kevin Hand]

And so we get. The electrons get sort of preferentially positioned such that you end up with a plus and a minus with water.

[Narrator]

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. 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.

[Kevin Hand]

The plus of a negative actually comes a little more from the hydrogen and oxygen differentiation. Right.

[Narrator]

So it's not the angle that they're coming down.

[Kevin Hand]

The angle plays a little bit. But the.

[Narrator]

Okay, that's just my thanks for filling in my chemistry.

[Kevin Hand]

Yeah, 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.

[Narrator]

Yeah, that's what I thought. And it wouldn't be as effective at things we care about. Yeah, yeah.

[Kevin Hand]

And certainly, you know, coming when it comes to ice, you wouldn't get that beautiful hexagon. That is in part due to the, 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.

[Narrator]

Liquid ures, universal solvent, we call it.

[Kevin Hand]

Universal solvent for life on Earth.

[Narrator]

Right.

[Kevin Hand]

But you go to Titan and now you've got this cold. By our standards, liquid methane, lakes and seas. And liquid methane is nonpolar. And so you're talking about life arising and thriving in a non polar solvent. 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.

[Narrator]

I'm just saying if you go back 100 whatever years and when evolution was first a thing that people discussed, 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. All right? That's before we had the undersea vents, which got geochemical energy, thermal energy down there. So. And now, even in modern astrophysics, planetary astronomy, 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.

[Commercial Voice]

Yeah.

[Kevin Hand]

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.

[Narrator]

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 interwoven. There's this zone where the two have to make nice in the coffee lounge. Right? Okay.

[Kevin Hand]

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 control. See above.

[Neil DeGrasse Tyson]

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[Narrator]

I'm reminded in the movie 2010 where we learn where the life form that made the monolith came from. From 2001. And do you remember where it came from? Remind me, is it Europa?

[Kevin Hand]

Well, oh, yeah, but the bottle where it came from.

[Narrator]

But that was the solar system's outpost of this life was Europa.

[Kevin Hand]

That's right.

[Narrator]

And I think they found chlorophyll on the surface of Europa.

[Kevin Hand]

Right. So back then there was the thinking that. And in the movie they show the sort of a green underneath a green 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.

[Narrator]

Of course.

[Kevin Hand]

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. But of course.

[Narrator]

Are you sure you don't have. Are you authorized to divulge where we're not supposed to? Yeah, because in the books. Wait, 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.

[Kevin Hand]

That's right. But doing beautiful flybys.

[Narrator]

But you're not landing there.

[Kevin Hand]

Correct.

[Narrator]

You're heating the warnings of the aliens in 2010.

[Kevin Hand]

No, not at all. There's a cadence.

[Narrator]

Of course. That's what you'd have to say. That's just what you should say. But let's talk about Europa Clipper. Six year mission there and six years to get there. Yeah. And then you hang out there a bit, orbiting Jupiter, but doing some close flybys of Europa.

[Kevin Hand]

That's right.

[Narrator]

And it's very exciting.

[Kevin Hand]

Oh, it's tremendously exciting. And when we say flybys, normally when we think about a spacecraft flying by a world, it's thousands of kilometers away, the engineers here at JPL the pinball wizards are able to get the Clipper spacecraft.

[Narrator]

Wait, pinball wizards? Because you have multiple. The gravity of a hub Europa clipper is getting a gravity assist from what?

[Kevin Hand]

From Earth and Mars. And then once it's in the Jovian system.

[Narrator]

Right, so this is a two cushion pull shot to get to.

[Kevin Hand]

To get to Jupiter.

[Narrator]

To get to Jupiter.

[Kevin Hand]

Once at Jupiter, then we go off the cushions of Ganymede and Callisto a bit.

[Narrator]

Oh, so you get more gravity assist from the moons.

[Kevin Hand]

That's right, very quick. By that time it's gravity assist to slow us down.

[Narrator]

Yeah, because people forget that you can gravity assist in either way for your energetics. Yeah, yeah.

[Kevin Hand]

And so Ganymede and Callisto. It's a beautiful thing about the Jovian system, the Jupiter system, where those larger can actually help out the spacecraft engineers to get into all sorts of different orbits. And so will pinball wizards.

[Narrator]

Hence pinball wizards.

[Kevin Hand]

Yeah, exactly.

[Narrator]

Great title for them. Wait, are they okay with the title?

[Kevin Hand]

I use this endearingly with my engineering colleagues all the time and they like it.

[Narrator]

They like it.

[Kevin Hand]

Okay, great. 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.

[Narrator]

Like petals of a flower.

[Kevin Hand]

Petals of a flower. Exactly. Or think about like those Spirograph, I've had one.

[Narrator]

Yeah, Spirograph.

[Kevin Hand]

And so we'll orbit Jupiter, but make these flybys of Europa. And the close approaches.

[Narrator]

How close are you gonna get?

[Kevin Hand]

25Km.

[Commercial Voice]

Wow.

[Kevin Hand]

The closest ones.

[Narrator]

That's as close as any object has ever swung by anything.

[Kevin Hand]

It's gonna be extraordinary. And the images, half a meter per pixel.

[Narrator]

What?

[Kevin Hand]

Yeah. And the Galileo images. So think about how extraordinary the images.

[Narrator]

From Galileo, the spacecraft. Yeah, okay. Because he was. And he did have a telescope and he did look at Jupiter to make.

[Kevin Hand]

Sure we're on the right.

[Narrator]

Galileo did not have half a meter per pixel resolution.

[Kevin Hand]

So Galileo the astronomer.

[Narrator]

Yes.

[Kevin Hand]

Point of light. Galileo, the spacecraft. We get beautiful pictures at, you know, kilometer scale.

[Narrator]

Suppose you could just, just tell Galileo what you're about to do. What a privilege that would be.

[Kevin Hand]

Oh, absolutely. I mean that's 400 years ago. 400 plus years.

[Narrator]

That's not even. That's nothing. That's nothing in the history of our species. Just say, you know, one day we're gonna go there one of your medicean. So you're gonna close view of the surface ice, but you're not looking at the water below. And that's what you really care about.

[Kevin Hand]

Right? And so what Clipper has on board 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.

[Narrator]

And Hubble helps out.

[Kevin Hand]

And Hubble. Yep. 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.

[Narrator]

But that's only because there are cracks that might fill in with the water and then refreeze.

[Kevin Hand]

That's right. Subduction. Subsumption.

[Narrator]

What is subsumption? That shouldn't even be a word. Just my opinion here. Subsumption.

[Kevin Hand]

Yeah. There's a term coined by some colleagues of mine.

[Narrator]

Oh, so you all just made up the word as we do. Because I know there's subduction as when a continental plate goes under.

[Kevin Hand]

That's right.

[Narrator]

And then there's.

[Kevin Hand]

Yeah, and so substance.

[Narrator]

Give me some other words.

[Kevin Hand]

Here 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.

[Narrator]

Did it really need another word?

[Kevin Hand]

Okay, fine. Debatable. So with Clipper, we've got these cameras and spectrometers and then mass spectrometers that will allow us to taste any plume material coming out of Europa. We can taste any organic compounds, carbon compounds.

[Narrator]

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.

[Kevin Hand]

That's right, exactly.

[Narrator]

With your machine.

[Kevin Hand]

I'm a co investigator on the SUDA instrument, which is a dust analyzer, massoud, surface analyzer for dust at Europa. Acronyms these days are.

[Narrator]

I'll give you that. I'll give you a hall pass on that one.

[Kevin Hand]

They don't necessarily go by the first letter of the word anymore.

[Narrator]

Okay, so that's more of a passive expression because you have. You're not aiming for those. It has to sort of come to you if it happens to be spewed forth from the surface.

[Kevin Hand]

Exactly. Think about a kid with a bucket running through a snowstorm. 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. No.

[Narrator]

And these aren't big plumes like you find on Enceladus, but there is certainly upward movement.

[Kevin Hand]

Yeah. So I've been on a team that's used the Hubble Space Telescope and the James Webb Space Telescope to look for plumes on Europa.

[Narrator]

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.

[Kevin Hand]

This is.

[Narrator]

We got good people.

[Kevin Hand]

We can get amazing things. We got some people.

[Narrator]

Our people are good folks. Not just the astronomers, but of course the engineers that actually make it happen.

[Kevin Hand]

That's right.

[Narrator]

Shout out to the engineers here.

[Kevin Hand]

They get the hard stuff. Done. So. So Enceladus is a tiny moon. It's only 500km 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 1/7.

[Narrator]

So Europa is way bigger.

[Kevin Hand]

Way bigger. 3,000 kilometers away.

[Narrator]

I didn't even think about that.

[Kevin Hand]

Yeah.

[Narrator]

And so, so 500 kilometers in American speak, that's like 300 miles across.

[Kevin Hand]

Yeah.

[Narrator]

All right. It's still a nice object, but. But it's not like Europa.

[Kevin Hand]

Right.

[Narrator]

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?

[Kevin Hand]

You asking if our bucket's gonna catch a squid.

[Narrator]

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.

[Kevin Hand]

That's correct, yep.

[Narrator]

And I have a tiny cameo in there. You do? I did a tiny little cameo. I think it was on cn. They used actual footage of me on actual news, commenting. I said, I want to go ice fishing on Europa. Cut a hole, lower a submersible and see what's there. And expressing my enthusiasm for this, you.

[Kevin Hand]

And I, that if we could fish on Europa.

[Narrator]

Oh, man. So you were an advisor to that film.

[Kevin Hand]

That's right. And they did a fantastic job.

[Narrator]

That's why it was so good. Not cause I was in it, but because they thought about the science.

[Kevin Hand]

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 going to do Europa, we got to do Europa.

[Narrator]

Right.

[Kevin Hand]

And so they didn't know that much about the radiation environment of Europa.

[Narrator]

From Jupiter.

[Kevin Hand]

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. 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.

[Narrator]

This is sulfur that has been spewed forth from volcanoes faster than the escape velocity of IO.

[Kevin Hand]

That's right.

[Narrator]

Thereby contributing to the general orbital environment of Jupiter.

[Kevin Hand]

That's right. It gets spun up in Jupiter's magnetic field. Next thing you know, that sulfur ion is slamming.

[Narrator]

Well, it's an ion, so it responds to the very strong magnetic field.

[Kevin Hand]

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.

[Narrator]

Sulfate, Sulfate microbes on Earth.

[Kevin Hand]

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.

[Narrator]

Which is the same thing as what anyone would call peroxide.

[Kevin Hand]

Exactly.

[Narrator]

In the pharmacy.

[Kevin Hand]

Yes.

[Narrator]

That's that old joke. You know the old joke?

[Kevin Hand]

No, what's that?

[Narrator]

Someone goes to the bar and says, I like some H2O. And then they hand them a glass of water. And then someone sees that and says, I want some H2O2.

[Kevin Hand]

And so they get a glass of.

[Narrator]

Water and then they drink it. That'd be a very chemically literate bartender.

[Kevin Hand]

Not a very tasty. 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 radiolytically processed or decays to O2 oxygen. And telescopically, we see hydrogen peroxide and oxygen in the surface ice.

[Narrator]

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.

[Kevin Hand]

Right. Except we actually observe it. So to be clear, we see condensed phase oxygen on the surface of your body.

[Narrator]

And you think that's how you get it.

[Kevin Hand]

Right? We get it radioolytically. I do that in my lab.

[Narrator]

I love when you say that. I do it in my lab. Need somebody. My lab.

[Kevin Hand]

And that's the fun of, like, lab and spacecraft.

[Narrator]

I know. It's great. It's Great. And they go hand in hand.

[Kevin Hand]

Yeah. And so we can make predictions, and it's a lot of fun. But so of course, we know that oxygen is very useful for life on Earth, not just for microbes, but for.

[Narrator]

Well, for our kind of life, for microfauna, anaerobic life does not like oxygen. That's just to be clear.

[Kevin Hand]

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 zone.

[Narrator]

And this will give you some of the chemical gradient you described that you need.

[Kevin Hand]

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 battery.

[Narrator]

And that's how you make Godzilla. At least before this is the recipe for Godzilla. So we gotta wrap this up just one point. I care a lot about words and what they mean and how they're received. Europa has water underneath ice. You named this mission Europa Clipper. And a clipper ship from the 19th century floats on water.

[Kevin Hand]

Right.

[Narrator]

Swiftly. So who came up with the word clipper?

[Kevin Hand]

I don't know.

[Narrator]

Cause that's a little. You're not floating anywhere.

[Kevin Hand]

Right? Yeah, you still. So 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.

[Narrator]

Yeah. They're some of the fastest ships made. They're narrower, a lot of sails. The wind can take you before steamships, of course. That's right. Right.

[Kevin Hand]

And so, by the way, I think.

[Narrator]

The phrase, let's get there on a good clip, I think that comes from clipper ships. The clip is swiftly. The clipper ship gets you there fast. 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 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.

[Kevin Hand]

That's right.

[Narrator]

So in that sense, it was a clipper, but not in the sense that it's floating anywhere. I just gotta make. I gotta get that off my chest.

[Kevin Hand]

100%. Yeah. And some of that clipper terminology goes back to variation in launch vehicles and stuff.

[Narrator]

Okay. All right. Well, Kevin, great to have you back.

[Kevin Hand]

Thanks so much, Neil. My pleasure. And great to see you. And it's an exciting time.

[Narrator]

So if something bad or good happens to the Clipper mission, we gotta get you back on to talk about it. Okay. The laugh will cry when all the good things happen. We gotta get you back on. We won't do it while you're busily receiving the data, but if there's a break in there, you gotta come back on anytime and we can find your book Alien Oceans.

[Kevin Hand]

Alien Oceans.

[Narrator]

I love the assonance there.

[Kevin Hand]

Alien oceans search for life in the depths of space.

[Narrator]

Yes. There you go. All right. Good luck with that.

[Kevin Hand]

Thanks so much.

[Narrator]

For sure. This has been StarTalk JPL Edition. Oh yeah. Neil DeGrasse Tyson bidding you as always as they do here to keep looking up. Psst.

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[Neil DeGrasse Tyson]

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