Interstellar Ice: The Chemical Fingerprint of 3I/ATLAS

<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
<v Speaker 1>with our soothing Bedtime Astronomie podcast. Each episode offers a
<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for
<v Speaker 1>unwinding after a long day. Let's travel through the mysteries
<v Speaker 1>of the universe as you drift off into a peaceful
<v Speaker 1>slumber under the night sky.
<v Speaker 2>Imagine for a second, right that you're just standing in
<v Speaker 2>your backyard, okay, and out of absolutely nowhere, from like
<v Speaker 2>a completely unknown neighborhood, someone just chucks a snowball right
<v Speaker 2>over your fence.
<v Speaker 3>That would be a bit surprising.
<v Speaker 2>Yeah right. But here's the crazy part. Imagine if you
<v Speaker 2>could pick up that snowball and just by analyzing the
<v Speaker 2>specific type of ice inside it, you could perfectly map
<v Speaker 2>out the exact temperature, the environment, everything about the place
<v Speaker 2>where it was made.
<v Speaker 3>Oh wow, Yeah, that's a.
<v Speaker 2>Wild thought, it is, and that is exactly what astronomers
<v Speaker 2>have just done. But you know, on a galactic scale,
<v Speaker 2>we're talking about a cosmic interloper.
<v Speaker 3>Here, right, Comet three iat lists.
<v Speaker 2>Exactly Comet three ialys, and our mission today is to
<v Speaker 2>unpack this incredible discovery We're gonna look at how a tiny,
<v Speaker 2>like almost invisible chemical variation in the frozen water of
<v Speaker 2>this comet is literally rewriting our entire understanding of how
<v Speaker 2>planetary systems are born.
<v Speaker 3>Yeah, it really is profound. I mean, what's fascinating here
<v Speaker 3>is the sheer scale of what this tells us about
<v Speaker 3>the universe. We're looking at a cosmic fossil.
<v Speaker 2>A fossil, yeah, and.
<v Speaker 3>Reading this fossil allows us to basically peer into an
<v Speaker 3>ultra coold alien stellar nursery located somewhere deep deep in
<v Speaker 3>our galaxy.
<v Speaker 2>It's just mind blowing because you stand on this planet
<v Speaker 2>built on a very specific chemical foundation, and you just
<v Speaker 2>take it completely for granted every time you turn on
<v Speaker 2>a faucet or look out at the ocean.
<v Speaker 3>Right, we just assume the universe plays by our local rules.
<v Speaker 2>We do. But three iatles just fundamentally breaks those rules.
<v Speaker 2>But okay, before we can even dissect the ice in
<v Speaker 2>the chemistry, we have to talk about the monumental challenge
<v Speaker 2>of actually catching this rogue comet in the act.
<v Speaker 3>Oh. Absolutely, the logistics of the observation itself are just incredible.
<v Speaker 2>Because it was actively grazing our sun, right.
<v Speaker 3>The team at the University of Michigan, led by Lucy
<v Speaker 3>Salas Armonzano and Treesa Punic at Caranno. They pulled off
<v Speaker 3>something amazing here.
<v Speaker 2>Yeah, because here's the immediate physical problem. If you point
<v Speaker 2>a multimillion dollar optical telescope lens at a blazing star.
<v Speaker 3>You're going to instantly melt your equipment.
<v Speaker 2>Exactly, you just fry it. Traditional optical telescopes are they're
<v Speaker 2>designed to gather faint light from ancient galaxies.
<v Speaker 3>Yeah, they're basically giant light buckets.
<v Speaker 2>Right, So pointing that at our sun is like using
<v Speaker 2>a giant magnifying glass to burn a leaf, except the
<v Speaker 2>leaf is your highly sensitive, irreplaceable sensor array.
<v Speaker 3>Yeah, it's a very fast way to ruin a billion
<v Speaker 3>dollar instrument.
<v Speaker 2>So how do you look at it? I mean, trying
<v Speaker 2>to see this comet is like trying to stare at
<v Speaker 2>a tiny firefly buzzing directly in front of a stadium spotlight.
<v Speaker 3>That's a great analogy, actually, and the solution was to
<v Speaker 3>just abandon optical light entirely. Oh really, Yeah, you can't
<v Speaker 3>use visible light. So the team used the atacomma large
<v Speaker 3>millimeters of millimeter array which most people just call ALA right,
<v Speaker 3>Alma specifically, they used its atacomma compact array, and ALMA
<v Speaker 3>operates in the radio frequency spectrum, so it doesn't even
<v Speaker 3>see visible photons the way our eyes are, like the
<v Speaker 3>Hubble space telescope do.
<v Speaker 2>Okay, So it's not taking a picture in the traditional sense.
<v Speaker 3>Not at all. It's detecting long wavelength electromagnetic radiation that
<v Speaker 3>gets emitted by cold gas and dust.
<v Speaker 2>That makes me think of like trying to listen to
<v Speaker 2>the base of a car stereo through a solid brick wall.
<v Speaker 3>Oh yeah, exactly, Like you can't.
<v Speaker 2>See the car at all because the wall is blocking
<v Speaker 2>your line of sight, which in this case is the
<v Speaker 2>blinding glare of the sun. But you can perfectly feel
<v Speaker 2>those low frequency vibrations just bleeding right through the concrete.
<v Speaker 3>That mechanical analogy hits on the exact physics of what
<v Speaker 3>Alime is doing. It's tuning into the radio waves that
<v Speaker 3>pass right through all that solar interference. It's like having
<v Speaker 3>magical ultrapolarized sunglasses that filter out the stadium spotlight so
<v Speaker 3>you can just see the firefly perfectly.
<v Speaker 2>Wow, that's so cool. And Alimes down in Chili, right.
<v Speaker 3>Yeah, high up in the Atacama Desert in northern Chile.
<v Speaker 3>It's add an elevation of over sixteen thousand feet.
<v Speaker 2>Wait, why does it need to be so high up?
<v Speaker 3>Because water vapor in Earth's own atmosphere actually absorbs submillimeter
<v Speaker 3>radio waves.
<v Speaker 2>Oh icee.
<v Speaker 3>Yeah, so if you build Alime at sea level, Earth's
<v Speaker 3>humidity acts like a heavy blanket, it just muscles that base,
<v Speaker 3>keeping with your analogy, before it ever reaches the dish.
<v Speaker 2>So they put it in a bone dry desert, super
<v Speaker 2>high up.
<v Speaker 3>Exactly up there, the array has a crystal clear, unobstructed
<v Speaker 3>view of those radio frequencies.
<v Speaker 2>And they really needed every ounce of that clarity, didn't they,
<v Speaker 2>Because the window for this was terrifyingly tight, Oh, incredibly tight.
<v Speaker 2>Caught three iac lays just six days after its perihelium,
<v Speaker 2>which is the point where it physically flew closes to the.
<v Speaker 3>Sun, right the absolute closest approach.
<v Speaker 2>But okay, let me push back on that for a second.
<v Speaker 2>Why weight What do you mean, like, why wait six days?
<v Speaker 2>Why not point Alma at the comet months earlier, when
<v Speaker 2>it was further out in the Solar system, moving a
<v Speaker 2>bit slower, easier.
<v Speaker 3>To track ah right, because when a comet is deep
<v Speaker 3>in space, it is chemically silent.
<v Speaker 2>Chemically silent.
<v Speaker 3>Yeah, it's just a dormant, frozen rock. The molecules inside
<v Speaker 3>it are completely locked into a solid crystalline matrix. If
<v Speaker 3>you want to read its chemistry, you actually need those
<v Speaker 3>molecules to become an active gas.
<v Speaker 2>Oh okay, so you need the Sun to bake it.
<v Speaker 3>Precisely, as the comet approaches the Sun, it crosses what
<v Speaker 3>we call the snow line. The intense solar radiation starts
<v Speaker 3>to bake the surface, and that causes the ice to.
<v Speaker 2>Sublimate, sublimate, So it skips the liquid phase entirely, right.
<v Speaker 3>It goes straight from a solid into a massive expanding
<v Speaker 3>cloud of gas, which astronomers call the coma.
<v Speaker 2>So the Sun is basically acting as our laboratory furnace exactly. Well. Wait,
<v Speaker 2>that still doesn't fully explain the six day delay. No, Well,
<v Speaker 2>if perihelium is the moment of maximum heat, wouldn't that
<v Speaker 2>be the exact moment of maximum gas release? Why six
<v Speaker 2>days later?
<v Speaker 3>That comes down to a really interesting concept called thermal inertia.
<v Speaker 2>Thermal inertia, okay, see the outer.
<v Speaker 3>Layer of a comet is rarely pristine white ice. It's
<v Speaker 3>usually this very dark, porous crust made of carbon rich
<v Speaker 3>dust and organic compounds, so.
<v Speaker 2>It looks more like a charcoal briquette than a.
<v Speaker 3>Snowball, exactly like a charcoal briquette. So when the Sun
<v Speaker 3>hits that dark crust right at perihelion, the surface heats
<v Speaker 3>up instantly, but it takes time for that thermal wave
<v Speaker 3>to physically penetrate down into the deep interior of the nuclear.
<v Speaker 2>Oh where the ancient pristine ices are actually buried. Right,
<v Speaker 2>So the six days post paar helion is the thermal lag.
<v Speaker 3>You got it.
<v Speaker 2>It's the time required for the Sun's heat to bore
<v Speaker 2>through the protective outer shell, crack open the vault, and
<v Speaker 2>trigger those deep seated ices to violently expand and shoot
<v Speaker 2>out into space.
<v Speaker 3>And that violently expanding gas is what Alma is actually.
<v Speaker 2>Listening to man the timing on that. If they missed
<v Speaker 2>that window, the whole thing would just cool down and
<v Speaker 2>vanish back into the void.
<v Speaker 3>Yeah, I would have taken its secrets with it forever.
<v Speaker 2>So okay, they successfully recorded this chemical signature out of
<v Speaker 2>the Sun's blinding glare. But what exactly is boiling off
<v Speaker 2>the surface. Like, why do astronomers call it a cosmic fossil.
<v Speaker 3>Well, we have to understand what a comet physically is.
<v Speaker 3>They are famously nicknamed dirty snowballs. As we said, right,
<v Speaker 3>they're incredibly rich in water content mixed with all that
<v Speaker 3>dust and primordial rock. And because they spend billions of
<v Speaker 3>years in the deep near absolute zero freeze of interstellar space,
<v Speaker 3>their internal chemistry just doesn't.
<v Speaker 2>Change, doesn't degrade at all.
<v Speaker 3>Nope, it doesn't degrade, it doesn't interact. The water inside
<v Speaker 3>is literally frozen information. It's a perfect time capsule from
<v Speaker 3>the exact moment in location the comet first coalesced out
<v Speaker 3>of a stellar nebula.
<v Speaker 2>So they aren't just hazards or pretty streaks in the sky.
<v Speaker 2>They are literally the universe's flash drives.
<v Speaker 3>That's a perfect way to put it. They're randomly delivering
<v Speaker 3>data about alien star systems directly to our doorsteps, so
<v Speaker 3>we don't have to travel light years to study them.
<v Speaker 2>It's like think about ice core samples taken from Antarctica, right, paleoclimatology. Yeah,
<v Speaker 2>scientists drilled down and they get these ancient air bubbles
<v Speaker 2>trapped in the ice, and that tells us about Earth's
<v Speaker 2>past climate. Comets are doing the exact same thing, but
<v Speaker 2>for the.
<v Speaker 3>Whole galaxy exactly. Panneca Carano notes that each interstellar comet
<v Speaker 3>brings a little bit of its history, its fossils from elsewhere.
<v Speaker 2>So what does this all mean if it's just frozen water?
<v Speaker 2>Isn't water the same everywhere in the universe? I mean
<v Speaker 2>H two O is just H two O. Right? A
<v Speaker 2>glass of water here is a glass of water a
<v Speaker 2>thousand light years away, And that.
<v Speaker 3>Assumption is exactly what this discovery shatters. Yeah, water is
<v Speaker 3>not a monolith. While commets and our oceans do contains
<v Speaker 3>standard H two O, they also contain a variation, a
<v Speaker 3>rare anomaly called semi heavy water.
<v Speaker 2>Semi heavy water, Okay, what makes it heavy?
<v Speaker 3>It's deuterated water or hdo hdo?
<v Speaker 2>Right?
<v Speaker 3>Normal hydrogen is just one proton, one electron, super simple.
<v Speaker 2>The most abundant element in the universe, exactly.
<v Speaker 3>But deuterium is a heavy isotope of hydrogen. It has
<v Speaker 3>that same proton and electron, but it also has a
<v Speaker 3>neutron sitting in the nucleus.
<v Speaker 2>Okay, an extra neutron that doesn't sound like a huge deal.
<v Speaker 3>Well, it literally doubles the mass of the atom.
<v Speaker 2>Oh wow. Yeah, a one percent increase in mass for
<v Speaker 2>a single atom is massive exactly.
<v Speaker 3>So when that heavy deuterium bonds with an oxygen and
<v Speaker 3>a normal hydrogen, you get semi heavy water. Hdo. And
<v Speaker 3>because of that extra mass, it behaves totally differently on
<v Speaker 3>a physical level, like how it freezes at a slightly
<v Speaker 3>higher temperature. It's noticeably denser. If you drop an ice
<v Speaker 3>cube made of heavy water into a glass of regular water,
<v Speaker 3>it'll actually sink to the bottom instead of floating.
<v Speaker 2>Wait, really, it sinks. Yeah.
<v Speaker 3>And it has huge effects on biology too. If you
<v Speaker 3>were to drink heavily concentrated deuterated water, it would eventually
<v Speaker 3>be fatal.
<v Speaker 2>Fatal from water.
<v Speaker 3>Yeah. Because the heavier mass of the deuterium atom forms stronger,
<v Speaker 3>more rigid hydrogen bonds. It physically jams up the fast
<v Speaker 3>moving protein machinery in our cell.
<v Speaker 2>Oh man, So it just breaks our biology pretty much.
<v Speaker 3>It famously prevents kineticore microtubules from pulling chromosomes apart during
<v Speaker 3>cell division, so cell division just stops.
<v Speaker 2>That is wild. It's a completely different chemical reality, even
<v Speaker 2>though it's technically still water, right.
<v Speaker 3>But for astronomers, the real value of HDO is in
<v Speaker 3>its toxicity. It's the fact that it acts like a
<v Speaker 3>cosmic barcode. A barcode, yeah, because we have a very
<v Speaker 3>specific baseline for this barcode. In our own local solar
<v Speaker 3>system on Earth and in commets native to our system.
<v Speaker 3>There is roughly only one molecule of semi heavy water
<v Speaker 3>for every ten thousand molecules of ordinary.
<v Speaker 2>Water, one in ten thousand, So it's.
<v Speaker 3>Super rare, incredibly rare. It's a very signal.
<v Speaker 2>It's like finding a microscopic typo or a misprinted coin.
<v Speaker 3>Yeah, exactly.
<v Speaker 2>Like if you have a giant bank vault with ten
<v Speaker 2>thousand regular pennies, finding the one penny stamped with a
<v Speaker 2>slightly different date tells you exactly which rare mint it
<v Speaker 2>came from.
<v Speaker 3>That's a great way to visualize it. And finding that
<v Speaker 3>one in ten thousand molecule on a rock speeding away
<v Speaker 3>from the Sun at over one hundred thousand miles per hour.
<v Speaker 3>That's why LMA was so critical.
<v Speaker 2>It's an astronomical needle in a haystack, it really is.
<v Speaker 3>But if we connect this to the bigger picture, the
<v Speaker 3>true shock. Wasn't just finding it, no, No, it was
<v Speaker 3>finding the baseline that it's measured against, and where that
<v Speaker 3>deuterium comes from in the first place.
<v Speaker 2>Okay, so where does it come from? How does this
<v Speaker 2>extra neutron get in there?
<v Speaker 3>We actually have to trace the timeline all the way
<v Speaker 3>back to the first few minutes after the Big Bank.
<v Speaker 2>Oh. Wow, we're going all the way back.
<v Speaker 3>We have to. This period is known as primordial nucleosynthesis.
<v Speaker 3>The universe was hot and dense enough for protons and
<v Speaker 3>neutrons to fuse together. This is when all the hydrogen
<v Speaker 3>and helium and the universe was forged. Right, and deuterium
<v Speaker 3>was created during this very chaotic window.
<v Speaker 2>But the universe was expanding rapidly, right, it was cooling
<v Speaker 2>down crucially.
<v Speaker 3>Yes, it expanded and cooled so fast that the nuclear
<v Speaker 3>fusion process was abruptly halted.
<v Speaker 2>Halted.
<v Speaker 3>Yeah, If the universe had stayed hot and dense for
<v Speaker 3>just a little bit longer, all of that deuterium would
<v Speaker 3>affused into helium and there would be no heavy water
<v Speaker 3>anywhere in the cosmos.
<v Speaker 2>Wow.
<v Speaker 3>But the rapid expansion froze the process in place. It
<v Speaker 3>left a fixed universal ratio of deuterium to regular hydrogen
<v Speaker 3>scattered all across the cosmos.
<v Speaker 2>Okay, so the raw materials for a stellar nursery are
<v Speaker 2>identical everywhere. Basically, Yes, Like a giant molecular cloud of
<v Speaker 2>gas condensing to form a star in the Andromeda galaxy
<v Speaker 2>has the exact same baseline ratio of hydrogen to deuterium
<v Speaker 2>as the cloud that formed our own solar system exactly.
<v Speaker 3>The universe provides the identical starting ingredients, but the local
<v Speaker 3>environment is what drastically changes how those ingredients combine into water.
<v Speaker 2>Here's where it gets really interesting. Wait, if the big
<v Speaker 2>banks at the ratio everywhere, how does a local environment
<v Speaker 2>change it.
<v Speaker 3>The primary driver of that change is extreme cold. The
<v Speaker 3>team highlighted that the chemical pathways required to actively concentrate
<v Speaker 3>deuterium into forming water ice, they require ambient temperatures dropping
<v Speaker 3>below roughly thirty kelvin.
<v Speaker 2>Thirty kelvin that translates to about minus four hundred and
<v Speaker 2>six degrees fahrenheit.
<v Speaker 3>It's staggeringly cold. Yeah, vastly colder than anywhere on Earth,
<v Speaker 3>colder than the dark side of our moon. It's hovering
<v Speaker 3>dangerously close to absolute zero, where atomic motion itself almost stops.
<v Speaker 2>So how does that cold environment physically act as a trap.
<v Speaker 2>The researchers use the phrase thermodynamic sieve. But what is
<v Speaker 2>the actual mechanism making the heavier water win the race
<v Speaker 2>to form ice?
<v Speaker 3>It revolves around a quantum mechanical principle known as zero
<v Speaker 3>point energy.
<v Speaker 2>Zero point energy, Okay, break that down for me.
<v Speaker 3>Even at absolute zero, molecules retain a baseline level of
<v Speaker 3>vibrational energy. Because deuterium is twice as heavy as normal hydrogen,
<v Speaker 3>the chemical bond it forms with oxygen has a lower
<v Speaker 3>zero point energy.
<v Speaker 2>So it sits deeper in the potential energy.
<v Speaker 3>Way exactly, meaning it is physically harder to break an
<v Speaker 3>oxygen uterium bond than an oxygen hydrogen bond.
<v Speaker 2>ICEE.
<v Speaker 3>So picture the vast swirling molecular clouds of a stellar nursery.
<v Speaker 3>You have all these microscopic dust grains floating around.
<v Speaker 2>Right, the dirty part of the dirty snowball.
<v Speaker 3>Yes, and these grains act as tiny catalytic surfaces. Oxygen
<v Speaker 3>atoms land on a dust grain, and hydrogen and deuterium
<v Speaker 3>atoms are just bouncing around on the gas, constantly attaching
<v Speaker 3>to the oxygen and then getting knocked back off by ambient.
<v Speaker 2>Thermal energy like musical chairs kind of.
<v Speaker 3>Yeah, But when the temperature of the entire cloud drops
<v Speaker 3>to thirty kelvin, there simply isn't enough ambient thermal heat
<v Speaker 3>left to knock the heavier deuterium out.
<v Speaker 2>Of the bond because it's sitting deeper in that energy.
<v Speaker 3>Well precisely, the lighter hydrogen atoms have a shallower energy,
<v Speaker 3>so even that tiny amount of thirty kelvin heat is
<v Speaker 3>enough to agitate them and break their bond. They just
<v Speaker 3>bounce off.
<v Speaker 2>But when a deuterium atom locks in it is secured.
<v Speaker 2>The cold just starves the system of the energy needed
<v Speaker 2>to reverse the reaction.
<v Speaker 3>Yes, as the ice mantle builds up around that dust grain,
<v Speaker 3>layer by layer, it selectively hoovers up the heavy deuterium,
<v Speaker 3>permanently locking it into the Furzen matrix.
<v Speaker 2>Man that is fascinating. So the atoms exist everywhere, but
<v Speaker 2>the cold acts like a sorting mechanism.
<v Speaker 3>Right, And because comets are uncontaminated time capsules, as we discuss,
<v Speaker 3>the moment that ice forms, the ratio is locked in forever.
<v Speaker 3>The HDO to H two zero ratio becomes this pure,
<v Speaker 3>uncorrupted thermometer.
<v Speaker 2>That's brilliant because you can't rely on complex molecules.
<v Speaker 3>Exactly, complex molecules like methanol or simple sugars. They can
<v Speaker 3>form through a variety of radiation exposures and energetic shocks
<v Speaker 3>over billions of years. Their presence is ambiguous.
<v Speaker 2>But the deuterium ratio is tied directly to quantum bond
<v Speaker 2>strengths and raw thermodenia. It tells you exactly how cold
<v Speaker 2>the oven was when the commet was baked. Beautifully said,
<v Speaker 2>So we know the universe set the raw baseline, We
<v Speaker 2>know the quantum mechanics of how ultra cold temperatures trap
<v Speaker 2>the heavy isotopes, and we know our own solar system
<v Speaker 2>produced a one to ten thousand ratio, which brings us
<v Speaker 2>to the data Alma pulled from three ialis. What was
<v Speaker 2>the ratio?
<v Speaker 3>This is the climax of Cella's arm and Zanos analysis.
<v Speaker 3>The revelation is that the HDO to H two O
<v Speaker 3>ratio and three ialis is more than thirty times higher
<v Speaker 3>than the comets formed in our solar.
<v Speaker 2>System, thirty times higher yeah.
<v Speaker 3>And more than forty times the ratio found in Earth's oceans.
<v Speaker 2>That is just a thirty x multiplier is not a
<v Speaker 2>rounding error. That is a completely different regime of physics.
<v Speaker 2>It totally is, because if the zero point energy trap
<v Speaker 2>requires profound cold to concentrate deuterium, then a thirty x
<v Speaker 2>spike means three i ad elast didn't just form in
<v Speaker 2>a cold environment.
<v Speaker 3>No, it formed in an absolute deep freeze, far colder
<v Speaker 3>than anything present during the birth of our own sun
<v Speaker 3>and planets.
<v Speaker 2>It implies a fundamentally different structural evolution for its home system,
<v Speaker 2>doesn't it.
<v Speaker 3>Oh, definitely, our solar system formed relatively close to massive
<v Speaker 3>hot o type stars. They flooded our local stellar nursery
<v Speaker 3>with ultraviolet radiation and ambient heat.
<v Speaker 2>Which kept our local dust grains warm enough to prevent
<v Speaker 2>massive deuterium enrichment. So we got the standard one to
<v Speaker 2>ten thousand ratio right.
<v Speaker 3>But three i at lasts must have formed in a dark, isolated,
<v Speaker 3>profoundly refrigerated pocket of a giant molecular cloud just sitting
<v Speaker 3>in the dark.
<v Speaker 2>Yeah.
<v Speaker 3>The gas and dust coalescing into its parent star were
<v Speaker 3>subjected to minus four hundred and six Greece fahrenheit for
<v Speaker 3>an incredibly long time. That allowed the ice grains to
<v Speaker 3>aggressively stockpile heavy water before the star ignited and blew
<v Speaker 3>all the remaining gas away.
<v Speaker 2>Sells Armanzano's conclusion is unequivocal. Then, the cloud of gas
<v Speaker 2>that formed this comet's home system had utterly different thermodynamic
<v Speaker 2>conditions than the environment that created our solar system.
<v Speaker 3>Completely different, and yet despite being born in a distant, isolated,
<v Speaker 3>deep freeze, it somehow ended up flying right through our
<v Speaker 3>Sun's corona.
<v Speaker 2>Which is crazy because the violence required to make that
<v Speaker 2>happen is staggering. We're looking at a rock born in
<v Speaker 2>a quiet, freezing nursery, which means it had to be
<v Speaker 2>violently ejected from its home star's gravitational grip to become
<v Speaker 2>an interstellar wanderer.
<v Speaker 3>Right. The mechanics of interstellar rejection usually involve catastrophic multibody
<v Speaker 3>interactions well as a new star system forms, giant gas
<v Speaker 3>planets similar to our Jupiter or Saturn condense out of
<v Speaker 3>the protoplanetary disk, but their orbits are rarely stable. Initially,
<v Speaker 3>they interact gravitationally with the massive disk of remaining gas
<v Speaker 3>and dust, and that causes them to migrate, oh.
<v Speaker 2>Like the Grand Tag model in our own solar.
<v Speaker 3>System, exactly where we think Jupiter migrated inward towards the
<v Speaker 3>Sun and then pulled back out, scattering millions of asteroids
<v Speaker 3>and comets in the process.
<v Speaker 2>So in the system that birth three Iron Aclis, a similar,
<v Speaker 2>perhaps even more violent migration was taken place.
<v Speaker 3>Most likely a migrating gas giant, or perhaps the gravitational
<v Speaker 3>perturbation of a closely passing neighboring star acted like a
<v Speaker 3>cosmic slingshot. Wow, it transferred immense orbital momentum to this
<v Speaker 3>specific comet, accelerating it completely beyond the escape velocity of
<v Speaker 3>its parents' start.
<v Speaker 2>Throwing it out into the galactic wilderness at hundreds of
<v Speaker 2>thousands of miles per hour yep.
<v Speaker 3>And it just wandered through the dark, empty expanse of
<v Speaker 3>the Milky Way for millions, maybe billions of years in total.
<v Speaker 2>Silence, until, by pure blind cosmic chance, its trajectory threaded
<v Speaker 2>the needle of our inner solar system.
<v Speaker 3>Exactly. It dived toward our Sun, sublimated its ancient heavy
<v Speaker 3>water ice, and right at that exact moment, the Alimee
<v Speaker 3>array in the Chilian desert was listening.
<v Speaker 2>The serendipity of that event is just it's matched only
<v Speaker 2>by the scale of what it teaches us.
<v Speaker 3>It's true. Astronomy has long operated on the assumption of mediocrity.
<v Speaker 2>You know, the idea that our solar system is a standard,
<v Speaker 2>run of the mill template for the rest of the galaxy.
<v Speaker 3>Right, we naturally project our local chemistry onto the stars
<v Speaker 3>we see in the night sky.
<v Speaker 2>But three im lass is the physical proof that planetary
<v Speaker 2>evolution is wildly diverse. The recipe they created Earth with
<v Speaker 2>its specific isotopic balance is literally just one flavor out
<v Speaker 2>of an unimaginable spectrum.
<v Speaker 3>Yeah, the galaxy is actively manufacturing planetary systems under conditions
<v Speaker 3>so extreme that they break our local chemical baselines by
<v Speaker 3>a factor of thirty.
<v Speaker 2>It forces a massive revaluation in the field of astrobiology, doesn't.
<v Speaker 3>It a huge one. We spend so much time looking
<v Speaker 3>for exoplanets in the Goldilock zone.
<v Speaker 2>Right, the orbital distance where temperatures allow liquid water to
<v Speaker 2>exist on the surface.
<v Speaker 3>But we always assume that the liquid water behaves like
<v Speaker 3>Earth's water.
<v Speaker 2>Oh wow, Yeah, what happens if you have a planet
<v Speaker 2>in the Goldilocks zone of an alien star, but its
<v Speaker 2>oceans are formed from the heavily deuterated thirty x concentrated
<v Speaker 2>ice of three itls.
<v Speaker 3>That's the million dollar question. An ocean of heavy water
<v Speaker 3>is denser, it's more viscous, it absorbs different waves links
<v Speaker 3>of light, altering the thermal dynamics of the planet's climate.
<v Speaker 2>And more importantly, as we discussed earlier, it poses a
<v Speaker 2>severe evolutionary hurdle. Heavy water actively disrupts terrestrial cellular mitosis.
<v Speaker 2>The strong hydrogen bonds of deuterium jam the mechanical pathways
<v Speaker 2>of DNA replication.
<v Speaker 3>Exactly, which means if biological life were to spark in
<v Speaker 3>a highly deuterated ocean, the fundamental architecture of its cellular
<v Speaker 3>machinery would have to evolve completely differently than life on Earth.
<v Speaker 2>It would have to it's proteins, it's cellular division mechanisms,
<v Speaker 2>its entire biochemistry would need to be engineered to handle
<v Speaker 2>the massive kinetic isotope effect of an environment steeped in
<v Speaker 2>heavy hydrogen.
<v Speaker 3>We aren't just talking about different environments here, We are
<v Speaker 3>talking about the potential for a completely unrecognized parallel track
<v Speaker 3>of biology.
<v Speaker 2>That is just wow. And that is the ultimate legacy
<v Speaker 2>of three ilis, isn't it. I think so? Yeah. It
<v Speaker 2>was a fleeting visitor, visible for just a matter of
<v Speaker 2>days before retreating back into the interstellar void. But by
<v Speaker 2>leveraging the unique capabilities of radio interferometry, astronomers were able
<v Speaker 2>to decode the frozen thermal record it carried.
<v Speaker 3>It really reminds us that every time we think we
<v Speaker 3>have the universe figured out, it throws a snowball over
<v Speaker 3>the fence that rewrites the rules.
<v Speaker 2>It really does. We are built from a very specific
<v Speaker 2>one to ten thousand recipe m hm. But somewhere out
<v Speaker 2>there in the ultra cold, heavily deudorated deep friezes of
<v Speaker 2>the Milky Way, the galaxy is cooking with an entirely
<v Speaker 2>different set of.
<v Speaker 3>Ingredients, and we now have the physical proof that those
<v Speaker 3>strange alien nurseries are actively seating the cosmos.
<v Speaker 2>It just makes you wonder, looking up at the night
<v Speaker 2>sky tonight, what strange, completely unrecognized forms of chemistry and
<v Speaker 2>perhaps entirely different forms of life might be brewing out
<v Speaker 2>there in the dark