Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomie podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: Okay, let's dive in. We're setting coordinates way out there today,
Speaker 2: folks past Jupiter, past Saturn, all the way out to
Speaker 2: the ice Giant.
Speaker 3: You're in this deep space. Yeah, and we're looking at
Speaker 3: one of its moons, aerial. There's some really fascinating new
Speaker 3: research out published in Chorus.
Speaker 2: Fascinating is almost an understatement. The main takeaway, the big
Speaker 2: headline here is that this research suggests Aerial, well, it
Speaker 2: used to have a massive ocean under.
Speaker 3: Its icy crust, a really massive one. We're talking potentially
Speaker 3: over one hundred miles deep. That's about one hundred and
Speaker 3: seventy kilometers.
Speaker 2: Okay, hold on, let's put that in perspective for everyone listening.
Speaker 2: One hundred and seventy kilometers deep. How does that stack
Speaker 2: up against say, Earth's oceans.
Speaker 3: Well, think about the Pacific Ocean. Its average depth is
Speaker 3: only about four kilometers maybe two point five miles, So
Speaker 3: this potential pasted ocean on Aerial it could have been
Speaker 3: something like forty times deeper on average than the.
Speaker 2: Pacific, twenty times on a moon. That's what much smaller
Speaker 2: than Earth. That's kind of mind bending.
Speaker 3: It absolutely is. We're picturing this relatively small, icy world
Speaker 3: way out in the cold, dark part of the Solar System,
Speaker 3: and it might have had this colossal hidden layer of
Speaker 3: liquid water. Yeah, it really makes you rethink.
Speaker 2: Thing, completely makes you rethink the potential for water and
Speaker 2: maybe even heat way out there. So Okay, the big
Speaker 2: question then is how how did scientists figure this out?
Speaker 2: Just by looking at the surface. What cleaves did they find?
Speaker 3: Yeah, that's the core of the research. Led by folks
Speaker 3: like Caleb Strom and Alex Patoff. They were basically doing
Speaker 3: geological detective work.
Speaker 2: Forensics on a planet terry scale exactly.
Speaker 3: They looked at Aerial's surface geology, which is pretty dramatic,
Speaker 3: that's a huge cracks and riches, and they tried to
Speaker 3: connect those features to what must have been going on
Speaker 3: inside the Moon and how it must have been orbiting Urinus.
Speaker 2: In the past, so reverse engineering the forces involved, that's
Speaker 2: the idea.
Speaker 3: What kind of stress would you need to break the
Speaker 3: Moon's crust in exactly the way we see it broken?
Speaker 2: All right, let's zoom in on aerial itself. Then the
Speaker 2: researchers called it pretty unique in terms of icy moons.
Speaker 2: What makes it stand out? Well?
Speaker 3: First off, its location and brightness. Is the brightest moon
Speaker 3: of Uranus and the second one out from the planet.
Speaker 3: It's the fourth largest, but still pretty modest in size.
Speaker 2: How modest are we? Talking?
Speaker 3: Only about seven hundred and twenty miles across eleven hundred
Speaker 3: and fifty nine kilometers give you a sense of that.
Speaker 3: It's roughly the driving distance from say, Tucson, Arizona, up
Speaker 3: to Salt Lake City, Utah. That's the entire width of
Speaker 3: the moon.
Speaker 2: Wow. Okay, so not huge, but clearly something dramatic happened
Speaker 2: on its surface. You mentioned this geological paradox. What's that about?
Speaker 3: It's this weird mix of really old and really young
Speaker 3: looking Kraine side by side.
Speaker 2: Old and young. How can you tell?
Speaker 3: The old parts are just covered in impact craters. Tells
Speaker 3: you that surface hasn't really changed much in maybe billions
Speaker 3: of years, it's just been sitting there getting hit.
Speaker 2: Okay, makes sense.
Speaker 3: But right next to those ancient battered areas you find
Speaker 3: these stretches of remarkably smooth terrain, and that smoothness suggests
Speaker 3: something wipe the slate clean relatively recently geologically.
Speaker 2: Speaking, like paving over the old roads.
Speaker 3: Kind of yeah. The prime suspect is cryovulcanism, icy eruptions
Speaker 3: from inside the moon that float out, froze, and smooths
Speaker 3: over the older crust.
Speaker 2: So internal heat, slushy ice, or water erupting that already
Speaker 2: hints at something interesting happening below it does.
Speaker 3: But even more compelling than the smooth plains were the
Speaker 3: giant cracks and faults, the sheer scale of the deformation.
Speaker 2: Right, you mentioned those, what kind of features are we
Speaker 2: talking about?
Speaker 3: Massive fraction, really long ridges, and these complex systems called grabins.
Speaker 3: A grabin is basically where a big block of the
Speaker 3: crust is just dropped down between two parallel faults.
Speaker 2: Like a valley formed by stretching and cracking exactly.
Speaker 3: And the key thing here, according to the paper, is
Speaker 3: the scale. These features on aerial are described as being
Speaker 3: at scales larger than almost anywhere else in the Solar.
Speaker 2: System late larger than almost anywhere. That's a huge statement,
Speaker 2: bigger than the cracks on Europa or the canyons on Mars.
Speaker 3: That's the claim. We're talking features that might stretch for hundreds,
Speaker 3: maybe over one thousand kilometers, and these seem to be
Speaker 3: part of a global pattern, suggesting the entire crust was
Speaker 3: under immense tension.
Speaker 2: Okay, if the cracks are that big, the forces must
Speaker 2: have been equally enormous. You don't get solar system scale
Speaker 2: cracks without solar system scale stress. Precisely, that's the fossil
Speaker 2: record we were talking about. To crack and drop sections
Speaker 2: of crust that large, the stress had to be intense, widespread,
Speaker 2: and probably prolonged. Points to two things working together, serious
Speaker 2: interurn heat softening things up, and really powerful external forces.
Speaker 2: And those external forces would be tides from Uranus.
Speaker 3: That's the prime candidate. Tidal forces, the gravitational push and
Speaker 3: pull from orbiting Uranus. This incredibly fractured landscape became the
Speaker 3: input data for their computer models.
Speaker 2: So they had the crime scene, these giant fractures. How
Speaker 2: do they use the models to find the culprit, the
Speaker 2: engine driving it all?
Speaker 3: Well, the first step was meticulously mapping the locations and
Speaker 3: orientations of all these major structures using the old Voyager
Speaker 3: two fly by images from back in the eighties.
Speaker 2: Right, our only close up looks so far.
Speaker 3: Yeah. Then they fed this map, this pattern of fractures
Speaker 3: into a computer program. This program was designed to simulate
Speaker 3: how an icy moon's crust would respond to different kinds
Speaker 3: of stress, specifically tidal stresses.
Speaker 2: Okay, let's break down tidal stress. We hear the term
Speaker 2: a lot with moons like Europa or Eo. How does
Speaker 2: it work?
Speaker 3: Basically, it's all about gravity changing depending on distance. When
Speaker 3: a moon orbits a big planet like Uranus, the side
Speaker 3: of the Moon closest to the planet gets pulled harder
Speaker 3: by gravity than the center of the moon does okay,
Speaker 3: and the center in turn gets pulled harder than the
Speaker 3: far side. So the overall effect is that the planet's
Speaker 3: gravity tries to stretch the Moon.
Speaker 2: Out, stretching it like along the line pointing towards Uranus exactly.
Speaker 3: And as the Moon moves in its orbit, maybe getting
Speaker 3: closer and farther away if the orbit isn't perfectly circular,
Speaker 3: the amount of stretching changes. The Moon gets squeezed and
Speaker 3: stretched squeezed in stretched.
Speaker 2: Ah like kneading dough.
Speaker 3: Almost yeah, Or imagine flexing a rubber ball. It constantly
Speaker 3: changes shape slightly. For a moon, it might bulge towards
Speaker 3: and away from the planet, relaxing back towards the sphere
Speaker 3: as it moves. That constant flexing is the tidal.
Speaker 2: Stress, and that flexing generates heat, right.
Speaker 3: Friction, That's the key. It's called tidal dissipation, where tidal heating,
Speaker 3: all that bending and flexing creates friction inside the moon,
Speaker 3: converting the energy of its orbit into internal heat.
Speaker 2: Like rubbing your hand ends together to warm them up,
Speaker 2: but on a planetary scale.
Speaker 3: Precisely you bend a paper clip back and forth, it
Speaker 3: gets warm eventually breaks a moon flexing under gravity, same principle,
Speaker 3: just over millions or billions of years, and that internal
Speaker 3: heat is what could potentially melt ice deep inside, creating
Speaker 3: an ocean.
Speaker 2: Got it. So the strength of this tidal heating, this
Speaker 2: flexing depends on the orbit.
Speaker 3: Crucially, Yes, and the most important factor dictating the strength
Speaker 3: of the tides is the shape of the orbit. Specifically,
Speaker 3: it's eccentricity.
Speaker 2: Eccentricity, Okay, what does that mean exactly.
Speaker 3: Eccentricity is just a measure of how much an orbit
Speaker 3: deviates from being a perfect circle. A perfect circle has
Speaker 3: an eccentricity of zero. The more elongated or oval shape
Speaker 3: the orbit.
Speaker 2: Is like a squashed circle.
Speaker 3: Yeah. The bigger the difference between its closest point to
Speaker 3: the planet and its farthest point, the higher the eccentricity value.
Speaker 2: And why does that matter for tidal stress?
Speaker 3: Because a higher eccentricity means a much bigger change in
Speaker 3: the gravitational pull the Moon experiences during each orbit. It
Speaker 3: gets stretched a lot more when it's closed and relaxes
Speaker 3: more when it's far. That bigger change in shape means
Speaker 3: much stronger flexing, more friction, and way more internal heat generated.
Speaker 2: Okay, so the modeling team basically asked how eccentric, how
Speaker 2: non circular did aerials orbit need to be in the
Speaker 2: past to generate enough tidal stress to create those gigantic
Speaker 2: fractures we see today exactly.
Speaker 3: They ran the models backwards essentially, and the answer they
Speaker 3: came up with was that aeriel needed a past orbital
Speaker 3: eccentricity of about zero point zero four.
Speaker 2: Zero point zero four Is that a lot? How does
Speaker 2: that compare it to its orbit.
Speaker 3: Now. Ah, here's where it gets really interesting. Ariel's current
Speaker 3: eccentricity is tiny, almost zero. That calculated past value of
Speaker 3: point zero four about forty times larger than its current value.
Speaker 2: Forty times. That's a massive difference. So its orbit used
Speaker 2: to be significantly more stretched.
Speaker 3: Out, significantly more effective at generating tides. Yes, even though
Speaker 3: in orbit with e eor a point zero four would
Speaker 3: still look pretty circular to the naked eye, the effect
Speaker 3: on tidal forces isn't linear. It ramps up much faster.
Speaker 2: Wait why isn't it linear? Why does a forty x
Speaker 2: increase in eccentricity cause way more than a forty x
Speaker 2: increase in stress.
Speaker 3: It comes down to the physics of how that energy
Speaker 3: turns into heat. The amount of tidal heating generated goes
Speaker 3: up much faster than the eccentricity itself. It's often related
Speaker 3: to the eccentricity squared or even higher powers depending on
Speaker 3: the specifics.
Speaker 2: Okay, so small changes in orbital shape can have these huge,
Speaker 2: outsized effects on the inside of the Moon.
Speaker 3: Massive effects. It means that this past orbit at point
Speaker 3: zero four eccentricity would have been incredibly efficient at churning
Speaker 3: up aerials interior, generating a ton of heat, enough heat
Speaker 3: potentially to melt a very deep layer of ice.
Speaker 2: That really puts it in perspective, especially when you compare
Speaker 2: it to a moon like Europa. Right, Jupiter's moon, Europa
Speaker 2: is kind of the poster child for tidal stress cracking
Speaker 2: its surface. It is Europa's surface is famously fractured by
Speaker 2: Jupiter's tides. But get this. The model suggests that for
Speaker 2: Aerial to get its specific massive fractures, its past orbit
Speaker 2: needed to be about four times more eccentric than Europe's
Speaker 2: current orbit. Four times more eccentric than Europa. Wow.
Speaker 3: Yeah, So if you think Europa looks beat up, aerials
Speaker 3: pass must have involved forces that were, in a sense,
Speaker 3: four times more intense than what Europa experiences today. It
Speaker 3: really drives home why the researchers described aerials features as
Speaker 3: being on a scale larger than almost anywhere else. The
Speaker 3: forces involved were just monumental. Okay, so we've got the
Speaker 3: cause this incredibly eccentric past orbit generating immense tidal stress
Speaker 3: way more than even Europa feels now. And we've got
Speaker 3: the effect these absolutely enormous fractures and grobins on the surface.
Speaker 3: Oh but why does that require an ocean. Why couldn't
Speaker 3: the moon just be solid ice all the way through
Speaker 3: and it just cracked under that incredible stress.
Speaker 2: Ah, that's the lynchpin of the argument. It comes down
Speaker 2: to how the ice shell breaks. The model showed something
Speaker 2: crucial about the style of fracturing. Okay, to get those
Speaker 2: specific features, these really long, parallel grobins where huge sections
Speaker 2: of crust drop down uniformly over vast distances, you need
Speaker 2: the outer ice shell to be able to flex significantly
Speaker 2: and globally in response to the stress.
Speaker 3: And a completely solid moon wouldn't do that. It would
Speaker 3: just shatter differently exactly if aerial was solid ice from
Speaker 3: surface to core, even if it got warm and a
Speaker 3: bit soft inside, it would still basically behave as a
Speaker 3: single rigid unit. When you subject a rigid body to
Speaker 3: those kinds of massive oscillating tidal forces, it tends to
Speaker 3: crack in a more brittle, maybe localized way. You wouldn't
Speaker 3: necessarily expect these huge, consistent, globe spanning fracture systems.
Speaker 2: So what does adding a liquid layer the ocean change?
Speaker 2: How does that allow for these specific giant gravens.
Speaker 3: The liquid water layer acts as a decoupling zone. Think
Speaker 3: of it like a layer of lubricant between the outer
Speaker 3: brittle ice shell and the solid rocky interior or.
Speaker 2: Core the moon decoupling, meaning the shell can move somewhat independently.
Speaker 3: Precisely because the ice shell is essentially floating on this
Speaker 3: liquid layer, it's not rigidly locked to the core. This
Speaker 3: allows the entire shell to flex, stretch, and relax much
Speaker 3: more easily in uniformly as a whole unit in response
Speaker 3: to those tidle poles.
Speaker 2: Ah I see, So the ocean allows the entire crust
Speaker 2: to participate in the flexing, leading to these large scale,
Speaker 2: consistent cracks when it finally breaks.
Speaker 3: That's the idea. Without that liquid layer providing the slipplane
Speaker 3: the decoupling, you likely wouldn't get the specific type and
Speaker 3: scale of features like the massive parallel gravins that dominate
Speaker 3: aerials observed terrain. The liquid layer facilitates that particular style
Speaker 3: of crustal failure.
Speaker 2: Okay, that makes a lot of sense. The ocean isn't
Speaker 2: just a consequence of the heat. Its presence is actually
Speaker 2: necessary to explain the way the surface broke. Yes, the
Speaker 2: researchers put it really well. In order to create those fractures,
Speaker 2: you have to have either a really thin ice shell
Speaker 2: on a really big ocean, or a higher eccentricity and
Speaker 2: a smaller ocean. So there's a trade off between how
Speaker 2: thick the ice is and how big the ocean is
Speaker 2: or how strong the tides were.
Speaker 3: Right, but the key point is, under the plausible conditions
Speaker 3: dictated by the past eccentricity, you need that liquid layer.
Speaker 3: The ocean is the non negotiable part of the equation
Speaker 3: to explain the geology.
Speaker 2: Which brings us back to that mind boggling depth one
Speaker 2: hundred and seventy kilometers. How did they land on that
Speaker 2: specific number?
Speaker 3: That figure represents the kind of ocean depth that would
Speaker 3: be compatible with the strongest plausible tidal stresses, the ones
Speaker 3: generated by that calculated past eccentricity of point zero four.
Speaker 2: So it's like the maximum possible ocean size given the
Speaker 2: forces involved.
Speaker 3: Essentially yes, given that level of intense tidle heating over
Speaker 3: a long period, the model suggests a significant fraction of
Speaker 3: Aerial's original water ice mantle could have melted, potentially creating
Speaker 3: an ocean that deep overlying the rocky core.
Speaker 2: It's still incredible that we can pieces together from fractures
Speaker 2: scene decades ago. But you mentioned a limitation the timing.
Speaker 2: Do we know when all this was happening? When did
Speaker 2: Ariel have the super eccentric orbit in this deep ocean.
Speaker 3: That's the big unknown right now and definitely a focus
Speaker 3: for future work. Orbital mechanics and moon systems are really complex.
Speaker 3: Moons interact, orbits evolve, Tidal forces themselves tend to make
Speaker 3: orbits more circular over very long, long time scales.
Speaker 2: So this highly eccentric phase was likely temporary, maybe billions
Speaker 2: of years ago.
Speaker 3: Probably likely happened earlier in the Solar system's history, but
Speaker 3: pinning down the exact timing is tough. What this study
Speaker 3: does is established the conditions required. It sets the physical boundaries,
Speaker 3: the eccentricity needed, the maximum ocean depth possible that any
Speaker 3: future model trying to trace Aerieal's history will have to match.
Speaker 3: It's a crucial baseline.
Speaker 2: Okay, let's broaden the view now. This research wasn't done
Speaker 2: in isolation, right, It's part of a larger look at
Speaker 2: the Uranian system.
Speaker 3: That's right. This is actually the second paper in a
Speaker 3: series from the same team. They previously published similar findings
Speaker 3: for another one of Uranus's inner moons, Miranda.
Speaker 2: Miranda, that's the one that looks like it was smashed
Speaker 2: apart and badly put back together, right, really bizarre surface.
Speaker 3: Yeah, Miranda's geology is famously chaotic, and the team's earlier
Speaker 3: work suggested that its weird features could also be explained
Speaker 3: by pass tidal heating driven by a period of high
Speaker 3: orbital eccentricity, likely also requiring a subsurface over.
Speaker 2: So the researchers are talking about potentially twin ocean worlds
Speaker 2: orbiting Urinus Aerial and Miranda.
Speaker 3: That's the tantalizing possibility they raise. It suggests that maybe
Speaker 3: the conditions for generating significant internal heat via tides weren't
Speaker 3: just a fluke for one moon, but perhaps a more
Speaker 3: common occurrence or a phase that multiple inner moons went
Speaker 3: through in the Uranian system.
Speaker 2: That really changes the picture of the Uranian system, doesn't it.
Speaker 2: We tend to think of it as just this cold, distant,
Speaker 2: relatively quiet place compared to Jupiter or Saturn.
Speaker 3: Absolutely, for a long time, Uranus and its moons seemed
Speaker 3: kind of dormant, just because they're so far from the
Speaker 3: Sun and the initial flyby didn't reveal obvious ongoing activity
Speaker 3: like Geyser's. But if Aerial and Miranda both potentially hosted
Speaker 3: deep liquid water oceans in their past driven by internal
Speaker 3: tidal heat, well, that paints a picture of a much
Speaker 3: more dynamic and geologically active system history than we assumed.
Speaker 2: It really underscores how important tidal heating is as an
Speaker 2: energy source, potentially everywhere in the outer Solar System, completely
Speaker 2: separate from sunlight.
Speaker 3: Definitely, it's a game changer for thinking about potentially habitable
Speaker 3: environments far from the star.
Speaker 2: But we're still working with pretty limited data here, aren't we.
Speaker 2: All of this is inferred from that single Voyager two
Speaker 2: flyby back in nineteen eighty six.
Speaker 3: That's the frustrating part. Yes, our only close up images
Speaker 3: are decades old, and because of the flyby trajectory and
Speaker 3: the way Uranus was tilted at the time, Voyager two
Speaker 3: only got good views of the southern hemispheres of these.
Speaker 2: Moons, so we've only seen half the picture.
Speaker 3: Literally, exactly as Tom Nordheim, one of the studies co authors, emphasized,
Speaker 3: we just haven't seen the northern halves of Aerial or
Speaker 3: Miranda up close. It's kind of amazing we can deduce
Speaker 3: this much from half a moon view decades ago.
Speaker 2: Does that limit how confident we can be in these
Speaker 2: ocean models.
Speaker 3: It certainly introduces uncertainty, but that's also where the predictive
Speaker 3: power of this modeling work becomes so valuable.
Speaker 2: Predictive power how so.
Speaker 3: Because the models aren't just explaining the features we have
Speaker 3: seen based on the physics of how the entire Moon
Speaker 3: should respond to those global tidal stresses. So the models
Speaker 3: actually make specific predictions about what kind of features like
Speaker 3: the orientation and location of major fractures and ridges, we
Speaker 3: should find on the unseen northern hemispheres if this whole
Speaker 3: scenario is correct.
Speaker 2: Ah, So it's like they've drawn a map for a
Speaker 2: future mission. If we're right, you should find giant cracks
Speaker 2: running this way up north.
Speaker 3: Precisely, they've provided testable hypotheses. They've essentially laid out the
Speaker 3: geological treasure map for a future orbitor or probe going
Speaker 3: back to Urinus. It makes the scientific case for a
Speaker 3: return mission much stronger.
Speaker 2: Yeah, you can see why they'd be pushing for it. Absolutely,
Speaker 2: the evidence is compelling. Potentially two ancient ocean worlds with
Speaker 2: specific predictions waiting to be verified. It really boils down
Speaker 2: to what the researchers themselves say. Ultimately, we just need
Speaker 2: to go back to the Urinus system and see for ourselves. Okay,
Speaker 2: let's try and pull this all together. We journeyed out
Speaker 2: to Ariel, this fairly small moon of Uranus. Its surface
Speaker 2: is covered in these absolutely enormous fractures and grabins, some
Speaker 2: of the biggest geological scars seen anywhere.
Speaker 3: Right evidence of massive past stress.
Speaker 2: The only way to generate that much stress, the model show,
Speaker 2: was through intense tidal forces from a past orbit that
Speaker 2: was way more eccentric, about forty times more than today,
Speaker 2: an orbit.
Speaker 3: Potentially four times more eccentric than even Europe's current one.
Speaker 2: And crucially, the way the crust broke forming those specific
Speaker 2: global features required the ice shell to be floating decoupled
Speaker 2: from the.
Speaker 3: Core, which means there had to be a liquid layer
Speaker 3: in between a subsurface ocean.
Speaker 2: A notion that under those extreme past conditions could have
Speaker 2: been over one hundred miles one hundred and seventy kilometers.
Speaker 3: Deep, just a staggering volume of water.
Speaker 2: And this isn't just aerial. Similar evidence points to its
Speaker 2: neighbor Miranda, potentially being a twin ocean world. It completely
Speaker 2: recasts the Uranian system.
Speaker 3: Yeah, it shifts review from seeing it as just cold
Speaker 3: endorment to a place that was likely once incredibly dynamic,
Speaker 3: wet and warm inside thanks to tidal energy.
Speaker 2: What stands out most to you from all this?
Speaker 3: For me, it's the sheer implication for water in the universe.
Speaker 3: If these relatively small moons orbiting a distant ice giant
Speaker 3: could generate enough internal heat to sustain oceans this massive,
Speaker 3: it just reinforces that the ingredients for potentially habitable environments
Speaker 3: liquid water and energy might be far more common out
Speaker 3: there than we used to think, even in the really cold,
Speaker 3: dark places. It definitely makes you wonder, and it leads
Speaker 3: to a final thought building on that idea of pass oceans.
Speaker 3: If Aerial and maybe Miranda really did have these deep
Speaker 3: oceans billions of years ago, how long could they have lasted?
Speaker 3: That's a billion dollar question, isn't it? How long can
Speaker 3: liquid water persist inside an icy moon once the period
Speaker 3: of intense tidal heating ends? Is it free slowly over eons?
Speaker 3: Good pockets remain liquid even today.
Speaker 2: Because the duration matters, right, right.
Speaker 3: Chemistry, it matters immensely. The longer you have liquid water
Speaker 3: in contact with a rocky core, especially if there's heat
Speaker 3: driving hydrothermal activity like vents on earth seafloor, the more
Speaker 3: time you have for complex chemistry to occur, time for
Speaker 3: interesting molecules to form, perhaps even precursors to life.
Speaker 2: So understanding not just if the ocean existed, but for
Speaker 2: how long is the next big step Exactly.
Speaker 3: This work opens the door to investigating the whole life
Speaker 3: cycle of these potential Outer Solar System motions. How long
Speaker 3: did they exist, how did they evolve? It seems the
Speaker 3: universe might be teeming with these hidden water worlds, vast
Speaker 3: and ancient, just waiting for us.
Speaker 4: To explore them further day
Speaker 3: Seas u