Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
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Speaker 2: breaking study, a massive data dump, and we just we
Speaker 2: distill it down into the core fascinating insights you need.
Speaker 3: And today we are undertaking a bit of a cosmic exploration.
Speaker 3: We're looking at a world that has for decades really
Speaker 3: represented our greatest hope for finding life beyond Earth, at
Speaker 3: least in our own solar system.
Speaker 2: We're talking about Jupiter's spectacular ice covered moon, Europa exactly,
Speaker 2: Europa is I mean, it's an absolute magnet for speculation,
Speaker 2: and for really good reason. Jupiter, the gas giant, it
Speaker 2: Shepper's nearly one hundred boons. It's an astronomical number.
Speaker 3: Truly, it is a whole solar system in itself.
Speaker 2: But Europa just stands out completely. The consensus among planetary
Speaker 2: scientists is that it harbors this vast global ocean of
Speaker 2: liquid salt water, and it's completely hidden beneath an icy excurior.
Speaker 3: It's a true water world, and it's isolated from the
Speaker 3: Sun's energy, which makes it well the ultimate enigma.
Speaker 2: It is the ultimate enigma. Yeah, but that potential for life,
Speaker 2: for habitability, it's always hinge on one single critical question.
Speaker 2: It's not simply does Europa have water, because I mean,
Speaker 2: we're highly confident that it does.
Speaker 3: Oh, absolutely, the evidence for the ocean is very strong.
Speaker 3: The real question, the one that matters, is does it
Speaker 3: have the dynamic energy that life needs to actually arise
Speaker 3: and sustain itself within that.
Speaker 2: Water And that distinction that is the absolute core of
Speaker 2: our analysis today. Yeah, the difference between just having the
Speaker 2: liquid the solve and having the active chemical engine. Right,
Speaker 2: we're pulling insights from a brand new peer reviewed study
Speaker 2: who was just published in the journal Nature Communications. This
Speaker 2: research it was led by Paul Byrne at Washington University
Speaker 2: in Saint Louis, and they looked past the water itself.
Speaker 2: They focused intensely on the geology.
Speaker 3: Of the seafloor, and their findings are well, they're significant.
Speaker 3: They suggest we might need to radically recalibrate our expectations
Speaker 3: about Europa. The team used physics and some really detailed
Speaker 3: geological modeling to pour what you might call cold water
Speaker 3: part in the stellar pun.
Speaker 2: Huh, Yeah, I was waiting for that one on.
Speaker 3: The long held excitement about Europa's potential to support life,
Speaker 3: at least life on its ocean floor.
Speaker 2: Okay, let's unpack this. What this new study is suggesting
Speaker 2: is that the bottom of that vast ocean, maybe one
Speaker 2: hundred kilometers deep, is geologically.
Speaker 3: Silent, silent, static inert and that's silence.
Speaker 2: I mean, if the modeling holds true, that is a
Speaker 2: catastrophic problem for any life that relies on chemical energy.
Speaker 3: It's a huge problem. And the credibility of this work
Speaker 3: is it's very high. This isn't just speculation. It's published
Speaker 3: in a top tier journal and it's grounded in meticulous calculations.
Speaker 3: They're combining known physical facts about Europa.
Speaker 2: It's density, its size, how it orbits Jupiter, all.
Speaker 3: Of that, and they combine it with detailed inferences drawn
Speaker 3: from how small rocky bodies behave, you know, including Earth
Speaker 3: and our own moon. The team Burn and his colleagues,
Speaker 3: they focused all their energy on that often overlooked part
Speaker 3: of the puzzle, the seafloor.
Speaker 2: And this is exactly where we need to start. We
Speaker 2: are diving down past the ice, past the ocean, right
Speaker 2: to the bottom. So let's establish the scale of this
Speaker 2: place for you, the listener. Let's call this first part
Speaker 2: the anatomy of a water world.
Speaker 3: It really helps to visualize it. First, Europa. It's actually
Speaker 3: it's quite modest in size, a little bit smaller in
Speaker 3: diameter than our own moon, right, so.
Speaker 2: You'd think smaller world.
Speaker 3: Less stuff, you would, But that scale is completely deceptive
Speaker 3: because its structure, how it's built, gives it this disproportionate
Speaker 3: immense volume of water.
Speaker 2: It really is staggering. I read that if you could
Speaker 2: somehow gather all the liquid water on Earth, all our oceans, lakes, rivers,
Speaker 2: ice caps, everything, everything, Europa is modeled to hold more
Speaker 2: water than all of it combined, and the moon itself
Speaker 2: is just a fraction of Earth's mass. That just blows
Speaker 2: my mind.
Speaker 3: It's why the volume is so immense, and it's why
Speaker 3: this little moon has always held such promise that volume
Speaker 3: is organized into three, three distinct layers.
Speaker 2: Okay, so let's start at the top.
Speaker 3: First, you have the ceiling, the ice shell. Current estimates
Speaker 3: they put that shield of ice at somewhere between fifteen
Speaker 3: and twenty five kilometers thick.
Speaker 2: Fifteen to twenty five kilometers. That is a colossal barrier
Speaker 2: between the surface and anything below it.
Speaker 3: An incredible barrier. Then beneath that shield lies the ocean itself,
Speaker 3: and it's not some shallow sea. We're talking about a
Speaker 3: depth of up to one hundred.
Speaker 2: Kilometers one hundred kilometers deep, I mean, just from perspective,
Speaker 2: that's ten times deeper than the Marianna's Trench, which is
Speaker 2: the deepest point we have here on Earth.
Speaker 3: Precisely it covers the entire Moon. And then finally, beneath
Speaker 3: that immense volume of salty liquid water, that's where you
Speaker 3: find the third layer, a rocky core. It's analogous to
Speaker 3: the silicate rock mantle and core of Earth.
Speaker 2: So you have the fundamental building blocks. You have liquid
Speaker 2: water and you.
Speaker 3: Have rock, the two main ingredients.
Speaker 2: But as you put it out earlier, having water and
Speaker 2: rock is what two thirds of the equation you need energy,
Speaker 2: So what makes that rock water interface, that seafloor so
Speaker 2: absolutely essential for life in this dark, sunless environment.
Speaker 3: Yeah, this is key. We have to completely move past
Speaker 3: the Earth based idea of photosynthesis. I mean, in a cold,
Speaker 3: dark deep sea environment like that, life can't rely on
Speaker 3: the sun. There is no sun, so instead it has
Speaker 3: to rely on chemical energy. It's a process we call chemototrophy.
Speaker 2: And we have examples of this on Earth. You have
Speaker 2: to think about those incredible, almost alien looking deep sea ecosystems.
Speaker 2: We've discovered, the ones cluster miles beneath the surface, completely
Speaker 2: cut off from the light exactly. We're talking about those
Speaker 2: giant tube worms, the colossal clams, all those specialized microbial
Speaker 2: mats living in total darkness.
Speaker 3: And those organisms they're not living off the sun. They
Speaker 3: are living off Earth's internal geological engine. That engine, it's
Speaker 3: driven by tectonic motion and volcanic activity, and it manifests
Speaker 3: as hydrothermal vents or ex smokers, the black smokers.
Speaker 2: Yeah.
Speaker 3: What happens is cold ocean water seeps down into the crust,
Speaker 3: it encounters these superheated magma chambers and it gets chemically altered.
Speaker 2: It's cooked, so it picks up all sorts of minerals
Speaker 2: and compounds.
Speaker 3: It does, and that water then shoots back out through
Speaker 3: these vents at extremely high temperatures, carrying this rich chemical.
Speaker 2: Soup with it, and it's that superheated plume, that chemical
Speaker 2: disequilibrium that is the literal catalyst for life.
Speaker 3: That's the perfect word for it, catalyst. The water coming
Speaker 3: out of those vents is rich in compounds like hydrogen sulfide,
Speaker 3: iron sulfides, methane, manganese, all these things that my microbes can.
Speaker 2: Well eat, they can metabolize it.
Speaker 3: And metabolize it. These compounds, especially hydrogen sulfide, provide the
Speaker 3: energy needed to kickstart and sustain microbial life at the
Speaker 3: absolute base of the food chain. The microbes consume those chemicals,
Speaker 3: and then everything else in that ecosystem consumes the microbes.
Speaker 2: So without that active geology, without that mechanism for energy
Speaker 2: cycling and chemical.
Speaker 3: Injection, then even one hundred kilometer deep ocean becomes a vast, cold,
Speaker 3: inert volume. It's just water and rock with no spark.
Speaker 2: This is where that Burn study just hit so hard.
Speaker 2: They looked at the Earth analogy and they calculated the
Speaker 2: odds of Europa providing those vents, and burn was very clear.
Speaker 2: When he presented his team's conclusion, he said, and this
Speaker 2: really drives the point home. If we could explore that
Speaker 2: ocean with a remote control submarine, we predict we wouldn't
Speaker 2: see any new fractures, active volcanoes, or plumes of hot
Speaker 2: water on the seafloor.
Speaker 3: And the implication of that statement is immediate and it's profound.
Speaker 3: If the seafloor is quiet, just like the model suggests,
Speaker 3: then there's no mechanism for cycling necessary nutrients from the
Speaker 3: rocky core up into the.
Speaker 2: Water, and no way to provide that vital thermal energy.
Speaker 3: None the energy required to sustain a deep sea chemo
Speaker 3: autotrophic ecosystem just isn't there. The lack of geologic activity
Speaker 3: at that vital rock water boundary, it essentially means the
Speaker 3: available energy is negligible. The ocean floor might as well
Speaker 3: be a geologically dead zone.
Speaker 2: But wait, I have to stop you on that point
Speaker 2: before we pivot to the calculation itself. Is it possible
Speaker 2: that just the fact that there is a rock water
Speaker 2: interface and that the water is salty, is that enough
Speaker 2: to produce some chemistry even without the big dramatic vents.
Speaker 3: That's a crucial question.
Speaker 2: Could in simple rock dissolution or reactions between the salt
Speaker 2: and the silicates produce some energy, even a little bit.
Speaker 3: It's a crucial point, and it moves us into a
Speaker 3: realm of let's call it lower energy life support. And
Speaker 3: yes it's possible, but the challenge there is immense Simple
Speaker 3: water rock reactions they happen everywhere, but they are incredibly slow, diffuse,
Speaker 3: very diffuse, and they don't release a lot of energy.
Speaker 3: Hydrothermal vents, on the other hand, driven by active tectonics
Speaker 3: and volcanism, they create an intense, localized disequilibrium, a sudden,
Speaker 3: dramatic injection of heat and chemicals. That's what allows life
Speaker 3: to thrive rapids accentrated source exactly. The Burn's study is
Speaker 3: primarily arguing that Europa lacks that powerful engine, the one
Speaker 3: that creates these high energy oases. So without that strong
Speaker 3: geological motor, any chemistry that does occur would be spread
Speaker 3: so thin, so slowly that it might not be enough
Speaker 3: to initiate or sustain a thriving ecosystem.
Speaker 2: That makes perfect sense. We're not just looking for a
Speaker 2: low energy trickle here, We're looking for the powerhouse, the
Speaker 2: thing that creates a concentrated biological starting point. So the
Speaker 2: big question is how do they reach this quiet conclusion.
Speaker 2: This brings us to the scientific heart of the study,
Speaker 2: which is the physics and the calculation itself. So let's
Speaker 2: talk about it. Where did the heat go?
Speaker 3: Absolutely the researchers, they relied on some really fundamental planetary
Speaker 3: physics and gravitational modeling. They had to figure out whether
Speaker 3: Europa possesses enough internal heat to cause that significant motion
Speaker 3: required for say, plate tectonics or volcanism at the seafloor.
Speaker 2: And they looked at two main heat sources.
Speaker 3: Right, two main sources. Yes, The first is the internal
Speaker 3: furnace residual heat, the heat left over from when the
Speaker 3: Moon first formed.
Speaker 2: Okay, so source number one. Why is Earth's core still
Speaker 2: blazing hot billions of years later? Yet Europa's core is
Speaker 2: predicted to be, you know, thermally inert.
Speaker 3: It's a classic example of how scale, just sheer size
Speaker 3: affects how a planet cools over cosmic time. Imagine you
Speaker 3: have a small cup of hot coffee versus a massive
Speaker 3: insulated urn of coffee.
Speaker 2: Okay, I'm waiting.
Speaker 3: They both start out hot, but the small cup. Because
Speaker 3: it has a low mass to surface area ratio, it
Speaker 3: loses its heat very very quickly to the surrounding air.
Speaker 2: Right it cools down in minutes. And Earth is the
Speaker 2: massive urn, holding onto its heat much more efficiently.
Speaker 3: Precisely, Earth is large enough. It's massive enough that it
Speaker 3: retains heat not just from its primordial formation, but also
Speaker 3: from the ongoing decay of radioactive isotopes within its mantle,
Speaker 3: things like uranium and thorium, so.
Speaker 2: That radioactive decay acts like a long term, slow burning
Speaker 2: internal heating element.
Speaker 3: Exactly. It's what sustains the convection in our mantle and
Speaker 3: drives plate tectonics over billions of years. It keeps the
Speaker 3: engine running.
Speaker 2: But Europer, being comparable in size to our own moon,
Speaker 2: it's the small cup of coffee.
Speaker 3: Correct, Euroba simply lacks the thermal mass to hold on
Speaker 3: to that primorbial heat for very long. The sheer volume
Speaker 3: of rock and the insulation effect are just so much smaller.
Speaker 3: Burn and his team they calculated that any heat that
Speaker 3: was originally present in Europa's rocky core, it would have
Speaker 3: entirely dissipated into space.
Speaker 2: Radiating away through the crust and.
Speaker 3: The ocean billions of years ago. So by the time
Speaker 3: we observe Europa today, that internal furnace is predicted to
Speaker 3: be cold thermally speaking, of course, so.
Speaker 2: We can scratch off residual planetary heat that's not driving
Speaker 2: any contemporary seafloor activity. The core is cold. That means
Speaker 2: the only viable engine left for keeping the geology dynamic
Speaker 2: must come from the outside.
Speaker 3: From Jupiter itself. From Jupiter, and this is where we
Speaker 3: move into the incredibly dynamic and very powerful realm of
Speaker 3: tidal heating. This is a kinetic energy source. It's the
Speaker 3: mechanical flexing and friction that's generated by Jupiter's immense gravity,
Speaker 3: and that force is strong enough to keep a moon
Speaker 3: geologically alive even without any residual internal heat.
Speaker 2: Here's where the physics gets incredibly powerful and really where
Speaker 2: the difference between life and no life just hangs in
Speaker 2: the balance. We have to compare Europa to its incredibly
Speaker 2: volatile sibling Aoo.
Speaker 3: The tail of two moons exactly the Io Europa contrast is.
Speaker 3: I mean, it's the perfect teaching moment in planetary science.
Speaker 3: Io is quite literally the most volcanically active body we
Speaker 3: know of in the entire solar system. Its surface is
Speaker 3: just constantly being repaved by spectacular eruptions.
Speaker 2: And that phenomenal activity is one hundred percent driven by tidal.
Speaker 3: Heating one hundred percent. But it's not just from Jupiter's
Speaker 3: simple gravity. It's driven by the asymmetry of that gravity,
Speaker 3: the unevenness of the poll.
Speaker 2: Okay, So explain that asymmetry for us. What makes EO's
Speaker 2: orbit so special and so heating. So.
Speaker 3: EO is the innermost of Jupiter's four large Gallean moons,
Speaker 3: and crucially, its orbit is not a perfect circle. We
Speaker 3: describe it as eccentric or erratic.
Speaker 2: And why is that? Why hasn't it settled down?
Speaker 3: Well, this eccentricity is maintained by a complex gravitational dance,
Speaker 3: a resonance with Europa and Ganymede, It's two outer neighbors.
Speaker 3: As these moons past each other in their orbits, they
Speaker 3: give Io a periodic gravitational tug, a little nudge, And.
Speaker 2: That little tug is enough to prevent Io from settling
Speaker 2: into a nice, stable circular path. It keeps it wobbly.
Speaker 3: Exactly because its orbit is elliptical or oval shaped. Io
Speaker 3: is constantly moving a little closer to Jupiter, and then
Speaker 3: a little further away. When it's close to that gas giant,
Speaker 3: the gravitational poll is extreme. When it's further away, the
Speaker 3: pool relaxes a bit. This constant differential and uneven tugging
Speaker 3: it subjects EO to intense cyclical stress.
Speaker 2: It's like taking a rigid stress ball and just continuously
Speaker 2: squeezing and relaxing at thousands and thousands of times a year.
Speaker 2: The friction generated inside must be immense.
Speaker 3: That's a perfect analogy. The immense constant friction generated by
Speaker 3: this physical deformation, this tidal flexing is what converts kinetic
Speaker 3: energy into thermal energy. It roils the rocks beneath Io's
Speaker 3: crust so intensely that the Moon's interior is largely molten, which.
Speaker 2: Is what drives those massive, NonStop volcanic eruptions that spew
Speaker 2: out sulfur and silicate lava.
Speaker 3: Io is truly alive because of Jupiter's intense asymmetrical gravitational
Speaker 3: pull and its own unstable orbit.
Speaker 2: Okay, so now let's turn to Europa. This is where
Speaker 2: the Burn study focuses most powerful calculations. What happens when
Speaker 2: you apply that same physics to Europa's position and its
Speaker 2: ore bit.
Speaker 3: Well, Europa's story is fundamentally different, while it is also
Speaker 3: tidally heated. I mean, if it weren't, the ocean wouldn't
Speaker 3: be liquid in the first place.
Speaker 2: Right, That's a key point. There is some heating.
Speaker 3: There is some heating, absolutely, but its orbital parameters are
Speaker 3: just far more moderate. For one, Europa is further away
Speaker 3: from Jupiter than Io is, and critically, its orbit is
Speaker 3: significantly more stable and more circular.
Speaker 2: So the stability that makes Europa's journey predictable is paradoxically
Speaker 2: the very thing that keeps its internal geological engine from
Speaker 2: running hot.
Speaker 3: That's the key finding of the study. The gravitational tug
Speaker 3: on Europa is much gentler, and it's much more symmetrical
Speaker 3: than it is on Io. This gentler poll does cause flexing,
Speaker 3: but the crucial differentiation that the Burn team made is
Speaker 3: related to the magnitude of that flexing on different parts
Speaker 3: of the moon.
Speaker 2: Okay, we need to nail this distinction down for the listener.
Speaker 2: What part of Europa is getting heated and what part
Speaker 2: is staying cold.
Speaker 3: So the calculation suggests that the tidal forces are strong
Speaker 3: enough to cause significant movement and friction within the outer
Speaker 3: ice shell, the ceiling, the ceiling. Yes, this is why
Speaker 3: we believe the ice shell is dynamic. It cracks, it refreezes,
Speaker 3: it might have plumes shooting out. This flexing in the
Speaker 3: ice is what generates enough heat to melt the water
Speaker 3: below the ice, and that's what maintains that one hundred
Speaker 3: kilometer deep liquid ocean.
Speaker 2: So that's the easy part of the equation. The heat
Speaker 2: keeps the ocean liquid.
Speaker 3: That's the easy part. The tough part is the rocky core,
Speaker 3: which is sitting one hundred kilometers beneath the ocean, the
Speaker 3: rock water boundary exactly. The calculation suggests that the energy
Speaker 3: required to melt a fifteen to twenty five kilometer ice
Speaker 3: shell is vastly, vastly less than the energy required to
Speaker 3: induce tectonic pleat motion and volcanic activity in a massive,
Speaker 3: dense rocky core.
Speaker 2: It's just a different physical problem.
Speaker 3: A completely different problem. Europe's orbital stability means the differential
Speaker 3: stress the squeezing that's applied to the deep rocky core
Speaker 3: is minimal. There just isn't enough friction being generated at
Speaker 3: that depth to sustain the high temperatures or the convection
Speaker 3: currents that you would need to drive seaford geology.
Speaker 2: So, in essence, the heat generated by Jupiter's pull is localized.
Speaker 2: It's concentrated in the elastic layers, the ice, in the
Speaker 2: liquid water, and it just dissipates before it can effectively
Speaker 2: fire up the planet's deep internal systems.
Speaker 3: Right, the core remains cold and inert.
Speaker 2: That is the precise verdict on tidal heating.
Speaker 3: It is the forces today are simply not strong enough
Speaker 3: to drive any sort of significant active geologic activity at
Speaker 3: that rock water boundary. The energy budget for geological activity
Speaker 3: is just insufficient. As Burn noted, we don't see any
Speaker 3: volcano shooting out of the ice today like we see
Speaker 3: on Io, and that's because the engine required to produce
Speaker 3: those intense geological events is, for all intents and purposes
Speaker 3: switched off.
Speaker 2: That is a staggering conclusion and is drawn purely from physics.
Speaker 2: So we've established that the residual heat from formation is
Speaker 2: long gone and the current dynamic heat source tidal flexing,
Speaker 2: is too gentle to reach the core. This leads us
Speaker 2: perfectly into the big so wet If the physics tell
Speaker 2: us that the sea floor is cold, and silent. What
Speaker 2: does a geologically quiet ocean actually mean for life? This
Speaker 2: is where we analyze the implication.
Speaker 3: And this is where we synthesize the findings and apply
Speaker 3: them directly to that core question of habitability. The conclusion
Speaker 3: from the Nature Communication study is stark. Europa likely lacks
Speaker 3: tectonic motion, It lacks warm hydrothermal vents, and therefore it
Speaker 3: lacks the robust cycling mechanisms that are required to create
Speaker 3: and sustain a vibrant ecosystem.
Speaker 2: It's a vast, dark, cold world at the bottom, despite
Speaker 2: the incredible volume of water that's sitting above it.
Speaker 3: And if the seafloor is inert, that essential link that's
Speaker 3: required to support deep sea life is broken. Let's just
Speaker 3: reiterate why that cycling mechanism is so critical. On Earth,
Speaker 3: the deep ocean is, for the most part, a chemical.
Speaker 2: Desert, right, There's not much going on, not much.
Speaker 3: At all, except where geological forces provide a massive concentrated
Speaker 3: influx of nutrients and energy from below.
Speaker 2: So if Europa lacks those vents, what are the remaining
Speaker 2: sources of chemistry available to that one hundred kilometer devotion.
Speaker 2: I mean, we have to consider every single possibility, no
Speaker 2: matter how remote.
Speaker 3: We essentially have two possibilities left, and both of them
Speaker 3: are what i'd call low energy options compared to hydrothermal vents.
Speaker 3: The first is, as you mentioned earlier, that slow water rock.
Speaker 2: Interaction, the trickling background chemistry.
Speaker 3: Which is very diffuse and likely way too slow to
Speaker 3: support a concentrated food web. And the second possible source
Speaker 3: must come from the top, from the ice itself.
Speaker 2: Okay, what do you mean.
Speaker 3: The surface of Europa is constantly being zapped by Jupiter's
Speaker 3: intense radiation field. The Moon is sitting inside these powerful
Speaker 3: radiation belts, and this bombardment of energetic particles, it breaks
Speaker 3: up water molecules on the surface, and it creates other
Speaker 3: compounds right exactly, things like oxygen, hydrogen, peroxide, and various
Speaker 3: sulfur compounds. So you have all these chemical oxidants sitting
Speaker 3: right there on the surface, essentially frozen into the ice shell.
Speaker 2: I see. So the theory is that if the ice
Speaker 2: shell is dynamic, if there are cracks, or or if
Speaker 2: the ice melts and refreezes a process called convection.
Speaker 3: Then these oxidants might eventually be mixed or transported down
Speaker 3: into the deep liquid ocean below, and this process, if
Speaker 3: it happens efficiently, could provide a different kind of chemical
Speaker 3: energy source for life. It could allow organisms to metabolize
Speaker 3: the compounds that are supplied from the surface.
Speaker 2: But the challenge there, I mean it seems immense too.
Speaker 2: You're talking about transporting surface chemicals through a twenty kilometer
Speaker 2: thick shield of solid eyes and then through one hundred
Speaker 2: kilometers of water just to get them to the rocky
Speaker 2: core where life might have begun.
Speaker 3: It's an issue of supply chain efficiency.
Speaker 2: That's a great way to put it.
Speaker 3: Hydrothermal vents deliver high energy nutrients directly and consistently right
Speaker 3: at the life rock boundary. It's like having a supermarket
Speaker 3: at your front door. The surface imported chemistry is a slow,
Speaker 3: complex and potentially intermittent delivery system. It relies entirely on
Speaker 3: the dynamics of the ice shell, which frankly we still
Speaker 3: do not fully understand.
Speaker 2: So the burden study. By reeling out the high energy
Speaker 2: guaranteed source the seafloor vents, it makes the whole life
Speaker 2: scenario immediately more challenging.
Speaker 3: Much more challenging, and it forces the scientific community and you,
Speaker 3: the listener to confront a very important distinction that I
Speaker 3: think we've glossed over for years. We've sort of been
Speaker 3: conditioned to think that finding liquid water automatically equals high habitability.
Speaker 2: Potentially, follow the water mantra and.
Speaker 3: The source material really challenges that simplicity head on. Just
Speaker 3: having liquid water, even in abundance, is not enough. You
Speaker 3: have to have sustained dynamic energy input at the most
Speaker 3: critical chemical interface, the water rock boundary. The ocean might
Speaker 3: be warm enough to be liquid, but the seafloor itself
Speaker 3: is predicted to be cold, inert, and featureless, offering little
Speaker 3: to no concentrated energy to initiate a food web.
Speaker 2: I have to challenge this conclusion slightly though the model
Speaker 2: predicts a lack of contemporary activity right now. But we've
Speaker 2: seen microbes on Earth. We call them extremophiles. They can
Speaker 2: survive incredible periods of stasis in extremely low energy environments.
Speaker 2: So if life did arise on Europe of billions of
Speaker 2: years ago, when the Moon may have had much more heating,
Speaker 2: couldn't a simpler form of life have adapted to survive
Speaker 2: in these low energy conditions today.
Speaker 3: That's a highly relevant query. It's a great point because
Speaker 3: we do see life adapting to what we would consider
Speaker 3: marginal conditions. However, we have to differentiate between sustaining life
Speaker 3: under marginal conditions and starting life.
Speaker 2: Ah okay, a biogenesis.
Speaker 3: A biogenesis, the origin of life. That process seems to
Speaker 3: require a highly dynamic, energetic, and chemically diverse environment, something
Speaker 3: like the ones we hypothesize existed near early Earth's hydrothermal vents.
Speaker 3: The chemical complexity that you need to build the first
Speaker 3: self replicating molecules is immense. You need a lot of
Speaker 3: stuff happening in one place.
Speaker 2: As you're saying, the startup energy is much higher than
Speaker 2: the maintenance energy.
Speaker 3: Precisely, if Europa's seafloor was intensely heated billions of years ago,
Speaker 3: maybe when the Moon had a more eccentric and more
Speaker 3: wobbly orbit it, then life could theoretically have started. But
Speaker 3: as that orbit stabilized and the core's heat dissipated, any
Speaker 3: thriving ecosystem would have been starved of its primary food source.
Speaker 2: The geological buffet would have closed down.
Speaker 3: It would have, and any surviving organisms would have needed
Speaker 3: to switch from a high energy metabolic process to an
Speaker 3: incredibly slow, low energy one. Maybe consuming those diffuse background
Speaker 3: chemicals or relying on those slowly imported oxidants from the surface.
Speaker 2: So in that scenario, we're not looking for a vibrant
Speaker 2: deep sea oasis. We're looking for what a microbial ghost town,
Speaker 2: organisms that maybe reproduce once every million years.
Speaker 3: It completely changes the search. We go from looking for
Speaker 3: a bustling city to looking for a deep freeze survival bunker.
Speaker 3: The implications of the Burn study suggest that even if
Speaker 3: life is present on Eurobit today, it would be incredibly sparse,
Speaker 3: very difficult to detect, and likely highly specialized to use
Speaker 3: the minimal energy available from slow rock water interaction or
Speaker 3: those sparse surface deliver oxidants.
Speaker 2: It's a profoundly different scientific challenge than finding a planet
Speaker 2: driven by its own internal thermal engine.
Speaker 3: Completely different, and that framing, I think makes the findings
Speaker 3: much clearer. The absence of a strong geological motor doesn't
Speaker 3: completely rule out life, but it certainly argues strongly against
Speaker 3: the kind of robust, complex deep sea life we initially
Speaker 3: hoped for, and it.
Speaker 2: Serves as a massive check on our enthusiasm. It reminds
Speaker 2: us that the physical mechanisms governing habitability are incredibly sensitive
Speaker 2: to astronomical mechanics like orbital resonance and planetary scale.
Speaker 3: It all comes back to physics.
Speaker 2: So if the calculations are right, the search for robust
Speaker 2: contemporary life just got a lot harder. But as scientist,
Speaker 2: we never accept a calculation, no matter how elegant it is.
Speaker 2: As the final word. We need direct observation always, and
Speaker 2: this moves us perfectly to our final segment discussing the
Speaker 2: path to certainty and the spirit of exploration.
Speaker 3: That's the absolute imperative of science. The study is a prediction,
Speaker 3: it's a very strong one based on established physics, but
Speaker 3: it is not a direct observation of the conditions one
Speaker 3: hundred kilometers below the ice. The only path to challenging
Speaker 3: or confirming this data is through a physical mission, and the.
Speaker 2: Key mission that's said to provide that certainty is already underway,
Speaker 2: the Europa Clipper spacecraft.
Speaker 3: The Clipper mission is just it's designed specifically to investigate
Speaker 3: Europa's potential habitability. It will perform dozens of close up
Speaker 3: fly bys. It'll circle Jupiter and then skim past Europa
Speaker 3: again and again to gather massive amounts of data. It's
Speaker 3: an incredibly ambitious mission with instrumentation designed to probe the
Speaker 3: very layers we've been discussing.
Speaker 2: So what specifically will Clipper be measuring that will help
Speaker 2: us verify or refute the Burn team's conclusions about the core.
Speaker 3: Clipper will provide crucial measurements that feed directly back into
Speaker 3: these models. For instance, it's going to use radar to
Speaker 3: penetrate the ice and measure its precise thickness and structure,
Speaker 3: And it will use gravity and magnetic field measurements to
Speaker 3: determine the depth and salinity of the ocean and importantly,
Speaker 3: the dynamic flexing of the ocean and the core.
Speaker 2: So if the core is being subjected to tidal forces
Speaker 2: strong enough to induce tectonics, the gravitational field measurements would
Speaker 2: likely show some kind of subtle but measurable signature related
Speaker 2: to that movement.
Speaker 3: Exactly, the instrumentation will be precise enough to measure the
Speaker 3: physical deformation how much the entire Moon flexes under Jupiter's pull.
Speaker 3: If the Moon is flexing significantly across its rocky interior,
Speaker 3: that indicates immense internal friction and heat, which would immediately
Speaker 3: contradict the Burn model.
Speaker 2: And if, however, the flexing is largely confined to the
Speaker 2: water and the ice layers.
Speaker 3: Then the Burn model stands validated.
Speaker 2: When can we expect this crucial data to start rolling
Speaker 2: in and hopefully answering these questions well.
Speaker 3: Clipper is scheduled for its deep investigation, starting with its
Speaker 3: first flyby in the spring of twenty thirty one, so
Speaker 3: we have a little while to wait. It's a patient pursuit,
Speaker 3: it is, but the level of detail we will gain
Speaker 3: after a few dozen fly bys will far far exceed
Speaker 3: anything we have today.
Speaker 2: It's also worth pausing just to acknowledge the human story
Speaker 2: behind this mission. The Clipper was conceived and championed in
Speaker 2: part by figures like Bill McKinnon, the Clarkway Harrison Distinguished
Speaker 2: Professor at Washington University. It just highlights the decades of
Speaker 2: relentless curiosity that propel planetary science forward. This is a
Speaker 2: scientific effort that really spans generations.
Speaker 3: And that institutional knowledge, the kind that allows researchers like
Speaker 3: Burn and his team to refine these models over time,
Speaker 3: is fundamental. It's what helps reduce the risks of major
Speaker 3: space missions. Every piece of data, whether it's confirming a
Speaker 3: planet's density or refining its orbital eccentricity. It allows us
Speaker 3: to build a more accurate picture before we commit billions
Speaker 3: of dollars to the trip.
Speaker 2: But I want to return to something Paul Burne said
Speaker 2: because I think it speaks to the greater spirit of
Speaker 2: exploration that goes beyond just the search for life. He
Speaker 2: isn't solely focused on the life question. His curiosity is
Speaker 2: fundamentally geological.
Speaker 3: He shifts the focus so beautifully. Even if Clipper confirms
Speaker 3: the seafloor is dead and inert, even if modern Europa
Speaker 3: is found to be lifeless, Burne is still incredibly interested
Speaker 3: in the fundamental science. His primary geological question is simply,
Speaker 3: I'm really interested to know what that seafloor looks like.
Speaker 2: That is profound. For all our discussions about the ocean
Speaker 2: and the ice, we have virtually no data on the
Speaker 2: ocean floor itself. Could be vast flat plains of rock,
Speaker 2: or it could be littered with ancient, cold, dormant geological features.
Speaker 2: We just don't know.
Speaker 3: It's the joy of pure discovery. The core motivation of
Speaker 3: a planetary scientist is to simply know what's out there,
Speaker 3: even if the answer doesn't fit our hopes for alien life.
Speaker 3: And Burn's broader view is very grounding for all of us.
Speaker 3: He says he's not upset if they don't find life
Speaker 3: on this particular moon, noting he is confident that there
Speaker 3: is life out there somewhere, even if it's one hundred
Speaker 3: light years away.
Speaker 2: So the value of the mission it isn't just a
Speaker 2: binary yes or no on life. It's about defining the
Speaker 2: parameters of habitability and understanding the complex, very geology of
Speaker 2: the Jovian System. Every planet in moon is a lesson
Speaker 2: in how physical laws manifest differently based on size, composition,
Speaker 2: and location.
Speaker 3: And the data gathered, regardless of the conclusion, will inform
Speaker 3: where we look next. If Europa, with its massive water ocean,
Speaker 3: turns out to be geologically inert because of its distant
Speaker 3: stable orbit, while that tells us that tidal heating is
Speaker 3: a highly sensitive variable in the habitability equation, and we would.
Speaker 2: Then focus our search for high energy ecosystems on moons
Speaker 2: with more eccentric unstable orbits closer to their parent planets.
Speaker 3: Exactly, every discovery, even a negative one, refines the search.
Speaker 2: This analysis has truly clarified the complexity of the physics
Speaker 2: at play here.
Speaker 3: Indeed, we've taken a really detailed look into the latest
Speaker 3: thinking on Jupiter's prime candidate for life, Europa, based on
Speaker 3: the rigorous physics presented in that Nature Communication study.
Speaker 2: So what does this all mean for you, the listener?
Speaker 2: Let's review the central insight. While Europa has the liquid
Speaker 2: water that first critical ingredient, the latest calculations show that
Speaker 2: the lack of dynamic tidal heating at the seafloor, which
Speaker 2: is driven by its distant and stable orbit around Jupiter,
Speaker 2: likely means the ocean floor is geologically quiet.
Speaker 3: And that quietness starves the ocean of the chemical and
Speaker 3: thermal energy that's needed for a thriving contemporary ecosystem. It's
Speaker 3: the difference between having a gigantic insulated pool of water
Speaker 3: and having a vibrant, geochemically active hydrothermal.
Speaker 2: Ecosystem, and Europa might just be the former.
Speaker 3: The life potential is well, it's significantly lower than we
Speaker 3: previously assumed. It shifts our focus to lower energy possibilities,
Speaker 3: or even just historical possibilities.
Speaker 2: Now for a final provocative thought to moll over, one
Speaker 2: that builds directly on the source material. We noted that
Speaker 2: the study focuses on contemporary life life right now, and
Speaker 2: it acknowledges the Moon may have had a lot more
Speaker 2: heating in the distant past.
Speaker 3: So if the Europa Clipper arrives in twenty thirty one
Speaker 3: and confirms a static, inert environment today, the search doesn't end.
Speaker 3: It just pivots to history. We would then need to
Speaker 3: ask if life did arise when the heating was more
Speaker 3: intense billions of years ago, and then start when the
Speaker 3: orbit stabilized and the core cooled, where would we look
Speaker 3: for the evidence for fossilized.
Speaker 2: Or long dormant microbial evidence exactly?
Speaker 3: That is a fundamental change in mission. If life started
Speaker 3: when the heat was on and then the stability of
Speaker 3: Jupiter's orbit led to geological silence, how would those ancient
Speaker 3: organisms have fared. Would they have simply been encased in rock,
Speaker 3: frozen into the cold seafloor, awaiting a geological revival that
Speaker 3: never came.
Speaker 2: That's a whole new type of exploration.
Speaker 3: It is that historical investigation requires us to think about
Speaker 3: how to search for ancient biosignatures, the chemical traces of life,
Speaker 3: rather than active metabolisms. It means future missions would need
Speaker 3: specialized drills and analysis tools designed to penetrate the seafloor rock,
Speaker 3: not just sample the water. It reminds us that habitability
Speaker 3: isn't a permanent switch. It's a continuum that can flicker
Speaker 3: on and off over geological time scales, and we may
Speaker 3: simply be arriving billions of years too late for the show.
Speaker 2: A truly fascinating and I think an essential recalibration of
Speaker 2: our expectations. We started this looking for an act the ecosystem,
Speaker 2: and we've ended by contemplating a frozen, fossilized past. Thank
Speaker 2: you for walking us through the complex physics governing Europa's
Speaker 2: silent seafloor s