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: I want you to close your eyes for a second. Well,
Speaker 2: don't do that for your driving, but if you're safe,
Speaker 2: close them and I want you to picture the Earth,
Speaker 2: not a map, not you know, a globe sitting in
Speaker 2: a classroom. I want you to picture that view from space,
Speaker 2: the blue marble. What is the one thing that just
Speaker 2: dominates that image.
Speaker 3: It's the water.
Speaker 2: It's the water. It's not the continents, it's not the clouds.
Speaker 2: It is that deep, overwhelming blue.
Speaker 3: It's the defining feature of our existence. Really, it really is.
Speaker 2: I was just ending at the beast last weekend, looking
Speaker 2: out at the Pacific, and it just it. It's you.
Speaker 2: The sheer volume of it all, seventy one percent of
Speaker 2: the surface, right. It drives our weather, it shapes our geology.
Speaker 2: I mean, it makes it. Most of your body weight.
Speaker 2: We are, for all intents and purposes, water creatures living
Speaker 2: on a water planet.
Speaker 3: We are Carl Sagan's pale blue dot. And you know,
Speaker 3: without that water, we're just another cratered rock spinning in
Speaker 3: the dark.
Speaker 2: We're Mars exactly. And because it is so fundamental, so
Speaker 2: absolutely non negotiable for life as we know it, you
Speaker 2: would just hmm, you'd assume that by now, by the
Speaker 2: year twenty twenty six, we would have the origin story
Speaker 2: of water completely locked down. You'd think we'd have the
Speaker 2: receipt for every single drop in the ocean.
Speaker 3: It seems like a reasonable assumption. Yeah, it's the most
Speaker 3: important substance we have, right.
Speaker 2: But here is the thing that absolutely blew my mind
Speaker 2: while I was reading this research packet. We don't or rather,
Speaker 2: the story we thought we knew, the one I definitely
Speaker 2: learned in high school earth science, might be completely wrong.
Speaker 3: It's not just wrong, the new data suggests it's well,
Speaker 3: it's mathematically impossible. It is a very bold statement, it is,
Speaker 3: but that is what the data is telling us. We
Speaker 3: are looking at a brand new study published literally yesterday,
Speaker 3: January twenty fifth, twenty twenty six, in the Proceedings of
Speaker 3: the National Academy of Sciences. It's a study that takes
Speaker 3: a look at some very very.
Speaker 2: Old rocks, rocks not from Earth.
Speaker 3: Not from Earth, No, and it completely upends our entire
Speaker 3: understanding of how Earth got its oceans.
Speaker 2: And what's so wild is that to figure out where
Speaker 2: earth water came from, they didn't look at Earth rocks
Speaker 2: at all. They looked at the Moon.
Speaker 3: They had to. It's the only clean witness we have.
Speaker 2: Okay, we are absolutely going to get into why that is.
Speaker 2: We're going to talk about a team led by doctor
Speaker 2: Tony Gargano. It's this massive collaboration with the University Space
Speaker 2: Research Association, the Lunaran Planetary Institute, NASA, jpl SCRIPTS, the
Speaker 2: heavy hitters, basically the heavy hitters of planetary science. Yeah,
Speaker 2: and we're going to unpack why they're findings based on
Speaker 2: a few handfuls of dust are forcing us to rewrite
Speaker 2: the history.
Speaker 3: Books and maybe even more importantly, why this rewriting of
Speaker 3: history might actually be the key to our future in space.
Speaker 3: It's this incredible twist.
Speaker 2: It's a total double edged sword. Right, it's bad news
Speaker 2: for the old textbooks, but it might be great news
Speaker 2: for future astronauts. Absolutely, But Before we get to the future,
Speaker 2: we have to deal with the past. We have to
Speaker 2: understand the story that we're now tearing.
Speaker 3: Down the standard model as it were.
Speaker 2: Yeah, so walk me through this, because I remember learning
Speaker 2: about the late heavy bombardment. It always sounds like a
Speaker 2: heavy metal band to me, but it was actually a
Speaker 2: geological era. What was the prevailing theory about why Earth
Speaker 2: has water?
Speaker 3: Well, to understand the old theory, you have to understand
Speaker 3: the environment in which the Earth was born. So you
Speaker 3: have to go back in time about four and a
Speaker 3: half billion years. The solar system isn't this polite, orderly
Speaker 3: clockwork mechanism we see today. It was a construction site.
Speaker 3: It was a shooting gallery, chaotic, violent, extremely hot. You
Speaker 3: have the proto sun igniting in the center, and surrounding
Speaker 3: it is the swirling disk of gas and dust. Now
Speaker 3: in that disk, there's a very very important and visible line.
Speaker 3: We call it the snow line or the frost line.
Speaker 2: Okay, is this like the snow line on a mountain?
Speaker 2: You know, you get above a certain altitude and rain
Speaker 2: turns to snow.
Speaker 3: It's the exact same principle, but it's based on distance
Speaker 3: from the Sun, not altitude. Inside that line, close to
Speaker 3: the newborn Sun, it is simply too hot for what
Speaker 3: we call volatiles to condense into solids.
Speaker 2: And volatiles that's just signed to speak for things that
Speaker 2: boil easily, right, like water.
Speaker 3: Exactly, water, carbon dioxide, methane, ammonia, all the good stuff
Speaker 3: for life. If you are inside the snow line, these
Speaker 3: things exist only as a gas, and the solar wind,
Speaker 3: this incredible torrent of particles from the young Sun, blows
Speaker 3: them away.
Speaker 2: So they can't stick around.
Speaker 3: They can't stick to the little dust grains that are
Speaker 3: clumping together to form planets. It's too hot. The stuff
Speaker 3: just vaporizes and gets blasted out to the colder outer
Speaker 3: Solar system.
Speaker 2: And Earth sits squarely inside that line.
Speaker 3: We are well inside it. Mercury, Venus, Earth, Mars. We
Speaker 3: are the inn rocky planets. So according to the laws
Speaker 3: of thermo dynamics, the building blocks of Earth, the planetesimals,
Speaker 3: they should have been dry, bone dry, bone dry. Think
Speaker 3: of a ceramic pot coming out of kiln. There is
Speaker 3: no moisture left in there. It has been baked out completely.
Speaker 2: So baby Earth forms. It's a molten magma covered rock.
Speaker 2: It's incredibly hot, it is no atmosphere to speak of,
Speaker 2: no water. It's basically a healthscape, a dry healthscape. Yes,
Speaker 2: but clearly something changed. I mean, I'm looking at the
Speaker 2: ocean right now. So the water had to arrive eventually.
Speaker 2: It had to come from somewhere.
Speaker 3: Correct, And since it couldn't have been there when the
Speaker 3: planet formed, the logic, the very sensible logic, dictated it
Speaker 3: must have been delivered from.
Speaker 2: Outside after things had cooled down a bit.
Speaker 3: Exactly. It had to come from past the snow line,
Speaker 3: where all that water and ice was still floating around.
Speaker 2: Into the cosmic delivery service.
Speaker 3: The asteroids and the commets, specifically a class of meteorite
Speaker 3: called sea type or carbonaceous chondrites. These are they are
Speaker 3: very primitive rocks that formed way out past Mars, out
Speaker 3: near Jupiter and beyond in.
Speaker 2: The cold, in the cold.
Speaker 3: Yes, And because they formed in the cold, they are
Speaker 3: loaded with water. It's not liquid water, it's locked inside
Speaker 3: their clay minerals. But some of these rocks are up
Speaker 3: to twenty percent water by weight.
Speaker 2: Wow, twenty percent. It's a very wet rock.
Speaker 3: It's a very wet rock. So the theory, the late
Speaker 3: heavy bombardment theory, stakes that about four point one to
Speaker 3: three point eight billion years ago, the Solar System went
Speaker 3: through this massive violent realignment. The giant planets Jupiter and Saturn.
Speaker 3: They shifted their orbits, and.
Speaker 2: When the gas giants move, everybody else has a really
Speaker 2: bad day.
Speaker 3: Gravity just goes haywire. They acted like a giant gravitational slingshot.
Speaker 3: They destabilized the asteroid belt. They've flung billions of tons
Speaker 3: of this rock and ice inward toward the Sun.
Speaker 2: And Earth was just standing in the way.
Speaker 3: We were in the cosmic crosshairers. The whole inner Solar
Speaker 3: System was a shooting out. We got pummeled. And the
Speaker 3: idea was that these impacts, millions and millions of them
Speaker 3: over hundreds of millions of years, they were the delivery mechanism.
Speaker 2: They brought the water.
Speaker 3: They brought the water they'd crashed into the young Earth.
Speaker 3: They'd vaporize on impact, release their steam into the thin atmosphere,
Speaker 3: and eventually, as Earth cooled, that steam would condense.
Speaker 2: Into rain, and it would rain for centuries.
Speaker 3: Millennia, filling the basins and creating the very first oceans.
Speaker 2: You know, it's such an elegant story. It's very clean.
Speaker 2: It explains everything. It explains why we have water despite
Speaker 2: being a hot planet. It explains the craters we see
Speaker 2: all over the Moon in mercury. It fits the timeline.
Speaker 2: So why why has it been challenged? Now? Why are
Speaker 2: doctor Gargano and his team saying, hold on a minute,
Speaker 2: they can't be right.
Speaker 3: Well, you know, imagine you have a theory that says
Speaker 3: a specific delivery truck dropped off a package at your house. Okay,
Speaker 3: you'd expect to find some evidence, right, some tire tracks
Speaker 3: in your driveway, maybe a receipt.
Speaker 2: Sure, some kind of proof of delivery.
Speaker 3: That's what scientists have been looking for, the chemical proof
Speaker 3: of delivery. If these see type asteroids brought the water,
Speaker 3: the chemical signature of those asteroids should be all over
Speaker 3: Earth's crust and mantle. We should see the fingerprints of
Speaker 3: that specific type of space rock everywhere we look, and
Speaker 3: we don't. We can't find them, or, to be more accurate,
Speaker 3: we can't trust what we find here on Earth.
Speaker 2: Why not? Is the equipment not good enough to see it?
Speaker 3: No, no, the equipment is phenomenal. Now, the problem is
Speaker 3: the witness. Earth is a terrible witness to its own history.
Speaker 2: Earth has amnesia.
Speaker 3: Geological amnesia is the perfect way to put it. Think
Speaker 3: about it. Earth is active, it's alive. We have plate tectonics.
Speaker 3: The ground you're standing on right now was not there
Speaker 3: four billion years ago. It was deep inside the planet.
Speaker 3: Right It gets recycled, constantly recycled. It's been subducted down
Speaker 3: into the mantle, melted into magma, mixed around like in
Speaker 3: a giant blender, and then spewed back out as new
Speaker 3: lava at a mid ocean ridge.
Speaker 2: And on top of that there's weather.
Speaker 3: Oh absolutely, rain, wind, glacier grinding mountains down, rivers, carving canyons.
Speaker 3: And then you have biology. You have plants growing over rocks.
Speaker 3: You have bacteria literally eating minerals. Earth is constantly, relentlessly
Speaker 3: erasing its own scars.
Speaker 2: So if a giant water bearing asteroid hit Earth four
Speaker 2: billion years ago, the crater is long gone.
Speaker 3: The crater is gone, the ejecta blanket is gone. The
Speaker 3: chemical evidence has been diluted and smeared and mixed into
Speaker 3: the great soup of the Earth's mantle over billions of years.
Speaker 2: So asking Earth, where did you get your water, it's
Speaker 2: kind of like asking a person who's undergone total plastic
Speaker 2: surgery and had their memory erased what they look like
Speaker 2: as a baby.
Speaker 3: That is a very vivid and slightly disturbing analogy, but yes,
Speaker 3: it's fundamentally correct. Earth cannot tell us the truth about
Speaker 3: the bombardment because Earth has changed too much.
Speaker 2: Which brings us finally to the neighbor, the silent partner
Speaker 2: in this whole cosmic dance, the Moon.
Speaker 3: The Moon is the perfect control group. It's the key
Speaker 3: to the whole miss It formed around the same time
Speaker 3: as Earth, in the same neighborhood, from very similar materials,
Speaker 3: but it's small. It cooled down fast. It died geologically speaking,
Speaker 3: It died geologically very very early on. There are no
Speaker 3: plate tectonic.
Speaker 2: No volcanoes recycling the crust.
Speaker 3: No atmosphere, so there's no wind and no rain to
Speaker 3: cause erosion.
Speaker 2: It's a museum.
Speaker 3: It is a time capsule. The surface of the Moon,
Speaker 3: what we call the regolith, is what doctor Gargano in
Speaker 3: the study calls a time integrated record. It has just
Speaker 3: been sitting there, exposed to the vacuum of space, collecting
Speaker 3: dust and debris for billions of years.
Speaker 2: So anything that hit Earth during the Late Heavy bombardment
Speaker 2: also hit the Moon. Because we're right next to each other.
Speaker 2: We're a system.
Speaker 3: In cosmic terms, we are holding hens. If Earth got
Speaker 3: showered with these waterbloons, the Moon got splashed too. But
Speaker 3: unlike Earth, the Moon didn't wipe off the water. It
Speaker 3: kept the chemical residue of everything that ever hit it
Speaker 3: locked in its surface layer.
Speaker 2: Okay, I want to pause on that word you used. Regolith. Yeah,
Speaker 2: because when I look at the footage from Paul eleven
Speaker 2: a Paul seventeen, I see the astronauts popping around in
Speaker 2: this gray stuff. It looks like dirt, looks like fine
Speaker 2: gray powder. Is it dirt?
Speaker 3: A geologist would have a fit if you called it dirt,
Speaker 3: and for good reason. Dirt or soil on Earth is
Speaker 3: an incredibly complex thing. It has organic matter, It has
Speaker 3: worm casings, decaying leaves, bacteria.
Speaker 2: It implies life.
Speaker 3: It absolutely implies a living ecosystem. Regolith is purely mechanical.
Speaker 3: It is rock that has been pulverized into dust. Imagine
Speaker 3: a single rock sitting on the surface of the Moon.
Speaker 3: A micrometeorite the size of a grain of sand hits
Speaker 3: it at twenty thousand miles per hour. It shatters the rock.
Speaker 3: Now over billions of years. That happens trillions upon trillions
Speaker 3: of times. So the top layer of the Moon is
Speaker 3: just this blanket of loose, jagged, heterogeneous debris. It's dust,
Speaker 3: its tiny shards of glass from the heat of impacts,
Speaker 3: its rock fragments.
Speaker 2: So the team's mission then was to look at this
Speaker 2: great powder samples brought back by the Apollo astronauts over
Speaker 2: fifty years ago and try to find that chemical receipt
Speaker 2: for the asteroids.
Speaker 3: Yes, they wanted to see if the tire tracks from
Speaker 3: the delivery truck were there in that lunar dust.
Speaker 2: But and there is always a butt in science, isn't there.
Speaker 2: It wasn't as simple as just putting the dust under
Speaker 2: a microscope and seeing a little label that says made
Speaker 2: in the asteroid belt.
Speaker 3: No, not at all. And this is where the story
Speaker 3: gets technically very difficult. This is why it took until
Speaker 3: twenty twenty six to get a clear answer, Because the
Speaker 3: Moon is a good witness, but it is a messy,
Speaker 3: messy witness.
Speaker 2: Messy how you just said it doesn't have wind or
Speaker 2: rain to mess things up.
Speaker 3: It doesn't, but it has impacts. And you have to
Speaker 3: remember those meteorites aren't landing softly. They are hitting at
Speaker 3: hypersonic speeds. They are exploding. The energy release is massive.
Speaker 3: It's like a nuclear bomb. Okay, when a rock hits
Speaker 3: the moon, it vaporizes itself, It melts the local moon
Speaker 3: rock it hits, it creates a plasma plume. Everything gets
Speaker 3: mixed together in this incredibly violent event.
Speaker 2: So it's like if I threw a chocolate bar into
Speaker 2: a blender full of vanilla ice cre and then just
Speaker 2: hit pulse for a fraction of a.
Speaker 3: Second, and then you did that a million times of
Speaker 3: rebillion years in random spots. The regolith has been reworked,
Speaker 3: it's been melted, it's been mixed, vaporized, recondensed. The signal
Speaker 3: of the asteroid the impact is blended almost seamlessly into
Speaker 3: the signal of the moon itself.
Speaker 2: So how on earth do you separate them? How do
Speaker 2: you unblend that smoothie? To figure out how much chocolate
Speaker 2: bar was originally there?
Speaker 3: That is the million dollar question. And for decades scientists
Speaker 3: use what we can call the old way. They looked
Speaker 3: for specific types of metals. They looked for cideriphiles, cierophile.
Speaker 2: I love that word. It sounds like someone who is
Speaker 2: just obsessed with hard cider.
Speaker 3: I wish no, it means iron loving. These are particular elements,
Speaker 3: things like iridium, platinum, gold, osmium, elements that chemically they
Speaker 3: bond very strongly with iron.
Speaker 2: Okay, And why do we look for those specific elements.
Speaker 3: It has to do with how planets form. When the
Speaker 3: Earth and the Moon were young and molten, they differentiated,
Speaker 3: the heavy stuff sanked, so the heavy iron sank to
Speaker 3: the center to form the core. And because these cider
Speaker 3: philes love iron, they hitched a ride. They sank down
Speaker 3: into the core too. So the crust of the Earth
Speaker 3: and the crust of the Moon are naturally very very
Speaker 3: poor in these metals. They're all locked away deep inside
Speaker 3: the core.
Speaker 2: Got it. So the surface is naturally metal pore exactly.
Speaker 3: But meteorates, they are primitive. They never went through that
Speaker 3: melting and differentiation process. They are chemically a complete jumble,
Speaker 3: and they are loaded with iridium and platinum.
Speaker 2: So the logic was simple. If you find a rock
Speaker 2: on the Moon's surface that has a lot of iridium
Speaker 2: in it, that iridium must be alien. It has to
Speaker 2: have come from an asteroid impact.
Speaker 3: That was the logic. It's a tracer, a chemical fingerprint,
Speaker 3: but it turns out it's a flawed fingerprint.
Speaker 2: Why didn't it work for this study? What's the flaw?
Speaker 3: It's because of that messy factor we just talked about,
Speaker 3: the intense heat of the impact. When an impact happens,
Speaker 3: you create this big pool of magma, and the physics
Speaker 3: gets weird in there. The metal might separate from the
Speaker 3: rock the silicate oh, it might sink to the bottom
Speaker 3: of the crater melt pool, or if it gets vaporized
Speaker 3: into a gas, the heavier metal might condense at a
Speaker 3: different temperature than.
Speaker 2: The lighter rock, so the signal gets distorted. It's not
Speaker 2: a true representation of the original meteorite exactly.
Speaker 3: It's a fractionation problem. You might find a rock that
Speaker 3: has a really high concentration of iridium, but you don't
Speaker 3: know if that represents the average amount of meteorite material delivered,
Speaker 3: or if you just got lucky and found a concentrated
Speaker 3: little nugget. It's too unreliable for calculating the total volume
Speaker 3: of material that arrived.
Speaker 2: So using metals is kind of like trying to count
Speaker 2: how many people were at a party by looking at
Speaker 2: the footprints in the muddy carpet, But the carpet has
Speaker 2: been shampooed in vacuum ten times since the party.
Speaker 3: That's a pretty decent analogy. Yeah, the deity is noisy.
Speaker 3: And so doctor Gargano and his team they realized that
Speaker 3: if they wanted a real answer, a mathematical hard limit,
Speaker 3: they couldn't rely on the metals. They needed to look
Speaker 3: at something much more fundamental. They needed to look at
Speaker 3: the rock itself.
Speaker 2: Oxygen.
Speaker 3: Oxygen. It is the most abundant element in the lunar crust.
Speaker 3: It makes up roughly forty five percent of the weight
Speaker 3: of any given Moon rock. You can't separate it out.
Speaker 2: It is the rock, okay, But oxygen is oxygen? Isn't
Speaker 2: it the air I'm breathing right now? How does oxygen
Speaker 2: tell you if a rock came from the Moon or
Speaker 2: from an asteroid.
Speaker 3: This is where we have to talk about isotopes, and
Speaker 3: I promise we'll keep this as painless as possible.
Speaker 2: You better my high school chemistry is uh, it's very rusty.
Speaker 3: Think of oxygen atoms as having different flavors. The standard flavor,
Speaker 3: the one you're mostly breathing right now, is oxygen sixteen.
Speaker 3: It has eight protons and eight neutrons in its nucleus.
Speaker 3: It's the light version. Let's call it vanilla vanilla perfect.
Speaker 3: But there are heavier, rarer versions. Oxygen seventeen has one
Speaker 3: extra neutron. Oxygen eighteen has two extra neutrons. Let's call
Speaker 3: them chocolate and strawberry.
Speaker 2: Okay, I'm with you, and I'm getting hungry, But okay, vanilla,
Speaker 2: chocolate and strawberry.
Speaker 3: Every single object in the Solar System has a specific recipe,
Speaker 3: a specific race of these three flavors. Earth has a
Speaker 3: very particular blend of vanilla, chocolate and strawberry oxygen. The
Speaker 3: Moon has a blend that is almost identical to Earth's,
Speaker 3: which is a clue to its origin. But that's another story, right.
Speaker 3: But those C type meteorites, the water carriers from the
Speaker 3: outer Solar System.
Speaker 2: Let me guess they have a totally different recipe.
Speaker 3: A totally different recipe. They have a distinct isotopic fingerprint.
Speaker 3: They are much richer in the heavy isotopes, the chocolate
Speaker 3: and strawberry in a way that really stands out from
Speaker 3: Earth and Moon rocks.
Speaker 2: So if you physically mix meteorite dust into moon dust,
Speaker 2: you change the flavor profile of the resulting rock exactly.
Speaker 3: You shift the overall ratio you add more chocolate and
Speaker 3: strawberry to the vanilla. But wait, there's a catch, of.
Speaker 2: Course there is. Science is never easy.
Speaker 3: The heat. Remember how the impact melts and vaporizes the rock.
Speaker 2: Yes, the blender effect.
Speaker 3: Well, heat also changes the isotope ratio. It's a process
Speaker 3: called fractionation. If you boil a pot of water, the
Speaker 3: lighter water molecules with the light vanilla oxygen sixteen, they
Speaker 3: evaporate a little bit faster. The heavy ones tend to
Speaker 3: get left behind, so the water that's left in the
Speaker 3: pot gets isotopically heavier.
Speaker 2: So the heat changes the flavor profile too. Doesn't that
Speaker 2: just ruin the entire experiment. How do you know if
Speaker 2: the change in flavor is because you added a meteorite
Speaker 2: or just because the rock got cooked in an impact.
Speaker 3: This is the absolute genius of the triple oxygen isotope method.
Speaker 3: This is the breakthrough, and this is why it's so
Speaker 3: much better than the metal method. The changes caused by
Speaker 3: heat by this fractionation, they follow a very strict, very
Speaker 3: predictable mathematical law. We call it mass dependent fractionation.
Speaker 2: Okay, that sounds a little scary.
Speaker 3: It just means the change depends on the weight on
Speaker 3: the mass. Oxygen eighteen is about twice as heavy relative
Speaker 3: to sixteen as seventeen is, so it fractionates twice as much.
Speaker 3: If you plot these changes on a graph, all the
Speaker 3: heat effects just slide up and down a specific line
Speaker 3: with a specific slope.
Speaker 2: Okay, so heat moves you up and down along this
Speaker 2: one predictable line.
Speaker 3: Right, But the meteorite signal, the mixing of a different
Speaker 3: recipe that comes from a totally different isotopic reservoir, it
Speaker 3: doesn't follow that mass law at all. It pushes the
Speaker 3: signal off the line sideways.
Speaker 2: Uh huh. So they can look at the grass and
Speaker 2: they can separate the two effects. They can say, okay,
Speaker 2: this much of the change is because it melted, but
Speaker 2: this jumps sideways off the line, that's the alien material.
Speaker 3: Precisely, they can mathematically unblend the smoothie. They can, finally,
Speaker 3: with high precision, isolate the impact or signal from the
Speaker 3: vaporization noise. It's an incredibly powerful tool. That is just
Speaker 3: it's so clever, it's brilliant, and they applied this high
Speaker 3: precision analysis to a massive suite of Apollo samples from
Speaker 3: different missions, different locations to get a really good representative
Speaker 3: average of the entire lunar surface.
Speaker 2: And this brings us to the verdict. The bottom line,
Speaker 2: the number. What did they find when they did all this?
Speaker 3: They found a signal. The meteorites are there. The tire
Speaker 3: tracks are in the dust. The analysis showed conclusively that
Speaker 3: the lunar reglyff contains at least one percent impact related
Speaker 3: material one percent give or take. Maybe a little more
Speaker 3: in some spots, maybe a little less. But generally speaking,
Speaker 3: the lunar surface is about one percent extraterrestrial, likely from
Speaker 3: these carbonaceous meteorites.
Speaker 2: Okay, so hearing that, my first thought is great, that
Speaker 2: confirms it. The theory was right. Meteorites did hit the Moon.
Speaker 3: It does confirm they hit, there's no question about that.
Speaker 3: But the problem isn't the presence. It's the quantity. That
Speaker 3: one percent number. It's not a confirmation. It's a hard limit.
Speaker 2: Walk me through the math on that. Yeah, why is
Speaker 2: one percent a problem? It sounds like a lot of rock.
Speaker 3: It is a lot of rock, but we have to
Speaker 3: scale it up. We know the surface area of the Moon,
Speaker 3: we know the mass of the regulith, layer, so we
Speaker 3: can calculate the total tonnage of meteorite material that one
Speaker 3: percent represents. Okay, then we have to adjust for Earth.
Speaker 3: Earth is bigger, it has more gravity, so it pulls
Speaker 3: in more rocks than the Moon does. There are models
Speaker 3: for that, so we can calculate, based that one percent
Speaker 3: lunar figure exactly how much total meteorite mass was delivered
Speaker 3: to the Earthman system during that bombardment window.
Speaker 2: Right, And then you just calculate how much water would
Speaker 2: be in that mass of meteorites, correct.
Speaker 3: Knowing that they are up to twenty percent water. And
Speaker 3: when you take that total mass of water delivered and
Speaker 3: you compare it to the actual amount of water that
Speaker 3: is sitting in Earth's oceans today, the math just breaks.
Speaker 3: It completely falls apart. It's nowhere near enough. It's not
Speaker 3: even in the right ballpark.
Speaker 2: Put it in perspective for me, how much water are
Speaker 2: we actually talking about here on Earth? It feels infinite
Speaker 2: when you look at it, But what's the number.
Speaker 3: Well, we often say that water is just a thin
Speaker 3: film on Earth's surface, which is true relative to the
Speaker 3: size of the planet, but in absolute terms, the number
Speaker 3: is staggering. The total mass of Earth's hydrosphere, oceans, ice caps, rivers,
Speaker 3: everything is about one point four to six sextillion kilogram.
Speaker 3: That's the one followed by twenty one zeros. It is
Speaker 3: one point six hundred quintillion tons. It's the number that
Speaker 3: is almost impossible for the human brain to process.
Speaker 2: That is, yeah, my brain just refuses to process that number.
Speaker 3: It's a global ocean three miles deep in places, and
Speaker 3: the meteorite delivery rate calculated from the hard limit on
Speaker 3: the moon rocks, it would only fill a tiny, tiny
Speaker 3: fraction of that basin.
Speaker 2: So it's not just that it comes up a little short.
Speaker 3: It's not a rounding error. It's like trying to fill
Speaker 3: an Olympic swimming pool with a thimble. You are adding water, sure,
Speaker 3: but you are never ever going to get a pool.
Speaker 2: So doctor Justin Simon from NASA, he was one of
Speaker 2: the authors on this paper. He had a quote about this,
Speaker 2: a very carefully worded.
Speaker 3: Quote, right, he said, and I'm paraphrasing. The results don't
Speaker 3: say meteorites delivered no water. They just make it very
Speaker 3: hard for them to be the dominant source.
Speaker 2: Dominant being the keyword there. They were a sprinkle, not
Speaker 2: the main course.
Speaker 3: Exactly. They were a contributor, but they were not the
Speaker 3: source of our oceans.
Speaker 2: This is a huge deal. This is fundamental shift in
Speaker 2: planetary science because if the water didn't come from the
Speaker 2: sky during the late Heavy bombardment, where on Earth is
Speaker 2: it from?
Speaker 3: Well, it's what Sherlock Holms would say, right when you
Speaker 3: have eliminated the impossible, whatever remains, however improbable, must be
Speaker 3: the truth. If it didn't come from outside.
Speaker 2: It had to have come from inside.
Speaker 3: It has to be indogenous. It was here all along.
Speaker 2: What does that mean? Exactly? Indogenous? How could it have
Speaker 2: been here all along? If the Earth was supposed to
Speaker 2: be bone dry?
Speaker 3: It means the water was part of Earth's original ingredients list.
Speaker 3: It implies that when Earth was forming from that swirling
Speaker 3: cloud of dust and gas, even though it was hot,
Speaker 3: even though it was inside the snow line, it somehow
Speaker 3: managed to grab onto water molecules.
Speaker 2: And trap them, trap them where deep inside.
Speaker 3: Deep inside the rock structure itself. Yeah, locked into the
Speaker 3: minerals of the mantle. Or Another theory is that maybe
Speaker 3: the Earth formed much much faster than we thought, and
Speaker 3: it trapped a huge amount of gas from the solar
Speaker 3: nebula before the Sun's wind blew it all away.
Speaker 2: And then what it just stayed down there.
Speaker 3: For a while. Then, over hundreds of millions of years, volcanoes,
Speaker 3: acting like planetary plumbing, burned the water out as steam
Speaker 3: geyser's volcanic eruptions, releasing it to the surface to form
Speaker 3: the oceans from within.
Speaker 2: This completely changes the personality of our planet. The old
Speaker 2: story was that Earth was a dry, dead rock that
Speaker 2: just got lucky. It got saved by a convenient asteroid
Speaker 2: shower right.
Speaker 3: A serendipitous accident of celestial mechanics.
Speaker 2: But this news story, it sounds like Earth was born wet,
Speaker 2: it was resilient, It held on to its life blood
Speaker 2: through the most violent, fiery period of its birth. That
Speaker 2: feels different.
Speaker 3: It suggests that habitability might be a more fundamental property
Speaker 3: of planetary formation than we thought. Maybe it's not just
Speaker 3: a lucky roll of the dice with asteroid impacts.
Speaker 2: That is a profound shift in thinking, and it opens
Speaker 2: up a whole universe of questions about other planets.
Speaker 3: It does. But and here is the pivot, the twist
Speaker 3: in the story that I promised at the start. While
Speaker 3: this study is a bit of a bummer, for the
Speaker 3: asteroid water theory on Earth, it is absolute twenty four
Speaker 3: care gold for something else, for the future, specifically for
Speaker 3: our future on the Moon.
Speaker 2: Because even though we just said the amount of water
Speaker 2: delivered was tiny compared to Earth's oceans, tiny is a
Speaker 2: relative term, isn't it.
Speaker 3: Everything is relative in space, one percent of the lunar
Speaker 3: regolith being meteorite material. When you do the math for
Speaker 3: the entire Moon, that translates to billions of tons of
Speaker 3: water delivered to the lunar surface. For Earth, that's a
Speaker 3: puddle in the Sahara. For the Moon, it's a fortune.
Speaker 2: It's the ultimate irony. The cosmic trash that wasn't enough
Speaker 2: to fill our oceans is the treasure that's going to
Speaker 2: let us leave.
Speaker 3: Precisely, the study confirms that the delivery trucks did arrive.
Speaker 3: Now on most of the Moon, that water is long gone.
Speaker 3: The Moon has no atmosphere, barely any gravity. If a
Speaker 3: water bearing meteorite hits the lunar equator at noon, the
Speaker 3: water vaporizes and the intense sunlight just boils it off
Speaker 3: into space.
Speaker 2: Instantly, So the equator is dry, bone dry.
Speaker 3: But there are places on the Moon where the sun
Speaker 3: never shines.
Speaker 2: The darkness at the edge of town.
Speaker 3: The permanently shadowed regions PSRs.
Speaker 2: These are the deep craters of the Poles.
Speaker 3: Right, Yes, the Moon's axis is very straight, it doesn't
Speaker 3: tilt like Earth's does to give us seasons. So at
Speaker 3: the North and South Poles you have these incredibly deep craters,
Speaker 3: like the massive South Pole Eate can Basin, one of
Speaker 3: the oldest impact features in the Solar System, where the
Speaker 3: crater floor has been in total complete darkness for maybe
Speaker 3: two billion years.
Speaker 2: It's the ultimate deep freezer.
Speaker 3: It is a perfect cold trap. The temperatures in these
Speaker 3: PSRs drop to minus two hundred minus two hundred and
Speaker 3: thirty degrees celsius. So when those meteorites hit other parts
Speaker 3: of the Moon and release their water vapor, some of
Speaker 3: those individual water molecules would just hop around the surface
Speaker 3: until they randomly landed in.
Speaker 2: A PSR, and once they land there, they.
Speaker 3: Stick, they freeze solid, and they never ever leave.
Speaker 2: So the one percent chemical signature that doctor Gargano found
Speaker 2: in the Apollo samples, that's just the trace residue left
Speaker 2: on the sunlit surface. But in these polar craters there
Speaker 2: could be massive concentrated to posits of ancient meteorite ice.
Speaker 3: Layers and layers of it accumulating for billions of years
Speaker 3: waiting for us. And this is why every major space
Speaker 3: agency NASA with this Artemis program, EESA, the Chinese CMSA,
Speaker 3: the Russians, They're all targeting the lunar South Pole.
Speaker 2: It's not just for the cool view, it's for the resources.
Speaker 2: It's a water rush.
Speaker 3: It's the great migration that the article talks about. It's
Speaker 3: about living off the land.
Speaker 2: Okay, so let's break down the shopping list. We land there,
Speaker 2: we send a rover into one of these dark craters,
Speaker 2: we find the ice. What do we actually do with it? Obviously?
Speaker 2: Number one is you drink it?
Speaker 3: Survival basic survival water is heavy. Launching a single bottle
Speaker 3: of water from Earth to the Moon costs thousands and
Speaker 3: thousands of dollars. It is the most expensive bottled water
Speaker 3: in the universe. If you can mine it there, if
Speaker 3: you can melt it and purify it, you don't have
Speaker 3: to bring it. That changes the entire economics of space
Speaker 3: travel instantly.
Speaker 2: Okay, so we drink it. We can use it to
Speaker 2: water plants in a greenhouse for food. What else?
Speaker 3: Radiation shielding This is a huge often overlooked one. Deep
Speaker 3: space is a wash in radiation, cosmic rays from distant supernovae,
Speaker 3: solar flares from our own sun. You need thick walls
Speaker 3: to protect human DNA from damage on long.
Speaker 2: Missions and water stocks. Radiation.
Speaker 3: Hydrogen is incredibly good at blocking cosmic rays and water.
Speaker 3: H two O is full of hydrogen. So if you
Speaker 3: build a habitat and you surround it with a jacket
Speaker 3: of water, or you mix the water into the regolift
Speaker 3: to make a kind of concrete and bury your habitat
Speaker 3: under that, you create a safe haven.
Speaker 2: That's incredibly smart. You live inside your water tank basically.
Speaker 3: But the killer app the thing that really matters for
Speaker 3: the future for becoming a spacefaring species is fuel. Rocket
Speaker 3: fuel rocket fuel water is H two O hydrogen and oxygen.
Speaker 3: If you run an electric current through it a process
Speaker 3: called electrolysis, which is high school science again, you can
Speaker 3: split it. You get oxygen gas, which you can use
Speaker 3: to breathe in your habitat, and you get hydrogen gas.
Speaker 2: And if you chill them down until they become.
Speaker 3: Liquids, you have liquid oxygen and liquid hydrogen LX and LHO.
Speaker 3: The most powerful, most efficient chemical rocket propellant known to man.
Speaker 3: It's what powered the Space Shuttle's main engines. It's what
Speaker 3: powers the core stage of NASA's SLS rocket today.
Speaker 2: So the Moon becomes a gas station in the sky.
Speaker 3: It becomes an interplanetary depot. If you can refuel your
Speaker 3: spacecraft on the Moon, you can go to Mars, you
Speaker 3: can go to the asteroid belt. You break what's called
Speaker 3: the tyranny of the rocket equation. You don't have to
Speaker 3: carry all of your fuel for the whole journey from
Speaker 3: the surface of Earth, which means you can carry more cargo,
Speaker 3: more science equipment, more people.
Speaker 2: It connects back to the meteorites in such a beautiful
Speaker 2: poetic way. The same bombardment that failed to give or
Speaker 2: Earth its oceans gave us the keys to leave Earth.
Speaker 3: It's amazing, isn't it. That tiny trickle of water frozen
Speaker 3: in the dark for eons. It could be the catalyst
Speaker 3: for us becoming a multiplanetary species.
Speaker 2: The article also touched on one more thing that I
Speaker 2: found just fascinating infrastructure, specifically building radio telescopes.
Speaker 3: Ah, yes, the view from the side.
Speaker 2: How does water help us build a telescope?
Speaker 3: It's about presence. It's about being able to stay. To
Speaker 3: build a massive, sensitive radio telescope on the far side
Speaker 3: of the Moon, you need infrastructure, you need power, you
Speaker 3: need robots, you probably need humans to service it. You
Speaker 3: can't do any of that if you're just camping for
Speaker 3: two weeks at a time. The water enables a permanent base.
Speaker 2: And why do we want a telescope on the far
Speaker 2: side of the Moon so badly?
Speaker 3: Because Earth is loud electromagnetically speaking, it's screaming. We are
Speaker 3: constantly broadcasting TV, radio, military radar, our cell phones, starlink satellites.
Speaker 3: We are blinding ourselves to the faint whispers of the
Speaker 3: radio universe. The far side of the Moon is the
Speaker 3: only place in the entire Inner Solar System that is
Speaker 3: permanently shielded from all of Earth's radio noise by thousands
Speaker 3: of miles of solid rock. It is the quiet zone.
Speaker 2: So if we use the water from the poles to
Speaker 2: build a permanent base, we can then build a listening
Speaker 2: post on the far side that could let us hear
Speaker 2: what the very beginnings of the universe.
Speaker 3: We detect signals from the cosmic dark ages, that period
Speaker 3: of time before the very first stars ignited. We could
Speaker 3: map the hydrogen of the early universe. We could do
Speaker 3: what kind of science that is literally impossible to do
Speaker 3: from Earth or even in Earth orbit.
Speaker 2: It all comes back to these rocks. Elk, I want
Speaker 2: to take a moment to appreciate the ground truth aspect
Speaker 2: of this whole deep.
Speaker 3: Dive round truth.
Speaker 2: Yes, we are talking about a cutting edge study published
Speaker 2: in twenty twenty six, but the samples, the actual rocks
Speaker 2: they put in their machines, those were collected.
Speaker 3: When between nineteen sixty nine and nineteen seventy two by
Speaker 3: the Apollo astronauts.
Speaker 2: That is over fifty years ago. That's just incredible to me.
Speaker 3: It is a testament to the foresight of the Apollo program.
Speaker 3: They didn't just collect rocks for the scientists of the
Speaker 3: nineteen seventies. They explicitly curated and sealed some of these
Speaker 3: samples for the future. They knew technology would improve. They
Speaker 3: knew you'd invent instruments like these incredibly high precision triple
Speaker 3: isotope mass spectrometers that didn't even exist when Neil Armstrong
Speaker 3: took that small step.
Speaker 2: Doctor Gargano in the paper calls himself and his team
Speaker 2: part of the next generation of Apollo scientists.
Speaker 3: He is. He's answering fundamental questions that the astronauts on
Speaker 3: the surface couldn't have even formulated back then. That is
Speaker 3: the incredible power of sample return. A rover on Mars
Speaker 3: is fantastic, but it's limited by the tools it carries
Speaker 3: on its back. When you bring the rock home, you
Speaker 3: can throw the entire weight of earth scientific capability at
Speaker 3: it for decades.
Speaker 2: To come, and it really emphasizes why we need to
Speaker 2: go back, not just to plant a flag and make footprints.
Speaker 2: We need more rocks, We need different rocks.
Speaker 3: We desperately need rocks from the poles. We need rocks
Speaker 3: from the far side. You have to remember the Apollo
Speaker 3: missions all landed in a very specific, relatively safe zone,
Speaker 3: the equatorial near side.
Speaker 2: The easy zone to get to the easy zone.
Speaker 3: Basing our entire understanding of the Moon only on the
Speaker 3: Apollo samples is like trying to understand the geology of
Speaker 3: the entire Earth. If you only ever landed in the
Speaker 3: Sahara Desert, you'd miss the rainforests, the ice caps, the Himalayas,
Speaker 3: the deep ocean. We need to diversify the collection to
Speaker 3: really truly nail down this water story.
Speaker 2: So let's bring it all home. Let's synthesize this for
Speaker 2: the listener who is trying to file this away in
Speaker 2: their brain because we've gone from the ancient past to
Speaker 2: the distant future.
Speaker 3: Sure, let's do a quick recap.
Speaker 2: Okay. Point one the old story. We used to think
Speaker 2: Earth form dry and got all of its water from
Speaker 2: a massive asteroid storm called the Late Heavy bombardment, right.
Speaker 3: The cosmic delivery service.
Speaker 2: Point two the investigation Doctor Gargano and his team used
Speaker 2: a new, very clever method, triple oxygen isotopes to separate
Speaker 2: the heat signal from the meteorite signal in the Apollo
Speaker 2: Moon rocks.
Speaker 3: And they found that the metia write signal is real,
Speaker 3: but it's small. Only about one percent of the lunar
Speaker 3: surface is made of this stuff.
Speaker 2: Point three the math failure. When you take that one
Speaker 2: percent and you scale it up to Earth, it is
Speaker 2: mathematically impossible for those asteroids to have filled our oceans.
Speaker 2: They're just warn't enough of them.
Speaker 3: Cover to a new conclusion, Earth's water is likely and
Speaker 3: doogenous it came from within the planet itself.
Speaker 2: And finally, point four, the silver lining that same trickle
Speaker 2: of meteorite water that was useless for filling Earth's oceans
Speaker 2: is now sitting concentrated as ice in the lunar poles,
Speaker 2: waiting to become the drinking water, radiation shielding, and rocket
Speaker 2: fuel for the next generation of space explorers.
Speaker 3: That's a perfect summary. We lost a simple, elegant origin story,
Speaker 3: but we gained a practical roadmap to the stars.
Speaker 2: I think I'll take that trade. But before we sign off,
Speaker 2: I want to leave everyone with one final thought, something
Speaker 2: that wasn't explicitly in the paper, but it's been nagging
Speaker 2: at me since I read it.
Speaker 3: Let's here.
Speaker 2: We spend so much time and energy looking for goldilocks planets,
Speaker 2: planets that are in the habitable zone, just the right
Speaker 2: distance from their star to have liquid water on their surface.
Speaker 3: Right the habitable zone. It's our primary target in the
Speaker 3: search for life.
Speaker 2: But this new study implies that just being in the
Speaker 2: right place might not be the whole story. If Earth
Speaker 2: didn't get its water from a lucky asteroid strike, if
Speaker 2: it held onto it because it's something intrinsic to how
Speaker 2: it was formed. What does that say about all the
Speaker 2: other planets in the universe?
Speaker 3: That is the big question? Isn't it?
Speaker 2: Does it mean that wet planets like Earth are actually
Speaker 2: common because water is just baked into the recipe of
Speaker 2: planetary formation from the start. Or does it mean that
Speaker 2: they're incredibly impossibly rare because holding onto that precious water
Speaker 2: while being blasted by a violent young sun is a
Speaker 2: miracle of physics.
Speaker 3: It shifts the variable for life. It suggests that life
Speaker 3: might not depend on a lucky rock throwing water at you,
Speaker 3: but on how robust the planet's embryo was to begin with,
Speaker 3: how well it held on to its inheritance.
Speaker 2: Are we common or are we a miracle of retention?
Speaker 2: I have a feeling the answer to that question is
Speaker 2: waiting for us, frozen in the dust of those dark
Speaker 2: craters at the south pole of the Moon.
Speaker 3: I think you're right. We just have to go and
Speaker 3: dig it up.
Speaker 2: We will be watching. Thank you so much for walking
Speaker 2: us through the isotopes and the sextilions and everything in between.
Speaker 2: It's truly amazing how a pile of old gray dust
Speaker 2: can change everything we thought we knew about our own
Speaker 2: blue marble.
Speaker 3: It was my pleasure. It's always good to re examine
Speaker 3: the neighborhood.
Speaker 2: For everyone listening. Thanks for diving deep with us, keep
Speaker 2: looking up, stay curious, and we'll catch on the next one.
Speaker 3: Goodbye everyone, see him