# Mars Had Multiple Water Worlds, NASA Rover Reveals

An episode of [Bedtime Astronomy](https://invisiblenetwork.ai/podcast/1736397134), 28 Sep 2026, 37 min.

Audio: https://dts.podtrac.com/redirect.mp3/api.spreaker.com/download/episode/75312249/marswaterp.mp3

NASA’s Perseverance rover has uncovered evidence that water transformed Mars in at least three distinct episodes. In Jezero Crater’s Margin Unit, the rover found igneous rocks containing carbonates and silica—clues to ancient groundwater, a long-vanished lake, and later heated fluids underground. The discovery reveals a far more complex watery history for Mars and raises new questions about whether its ancient environments could have supported microbial life. Thank you for listening to Bedtime Astronomy — your guide to the cosmos. New episodes on space exploration, NASA missions & the latest astronomy breakthroughs. This episode includes AI-generated content.

## Transcript

[0:03] Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
[0:07] Speaker 1: with our soothing Bedtime Astronomy podcast. Each episode offers a
[0:12] Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
[0:16] Speaker 1: unwinding after a long day. Let's travel through the mysteries
[0:20] Speaker 1: of the universe as you drift off into a peaceful
[0:22] Speaker 1: slumber under the night sky.
[0:27] Speaker 2: I want you to close your eyes for a second.
[0:29] Speaker 2: Assuming you're not driving.
[0:30] Speaker 3: Of course. Yeah, definitely keep them open if you're behind
[0:32] Speaker 3: the wheel.
[0:33] Speaker 2: Right, exactly. But if you're sitting safely somewhere, I want
[0:37] Speaker 2: you to picture yourself standing in a place of just
[0:41] Speaker 2: absolute profound silence.
[0:43] Speaker 3: Like quieter than anywhere on earth.
[0:45] Speaker 2: Exactly. You're standing on the edge of this massive, ancient,
[0:49] Speaker 2: completely dried up lake bed. And the ground right beneath
[0:54] Speaker 2: your heavy boots, it's dusted in this incredibly fine, powdery,
[0:59] Speaker 2: rust-colored dirt.
[1:00] Speaker 3: There's red dust everywhere. Everywhere.
[1:01] Speaker 2: Everywhere. And if you look up, the sky isn't blue.
[1:04] Speaker 2: It's this hazy, almost alien butterscotch color.
[1:08] Speaker 3: Which is such a wild thing to try and visualize.
[1:11] Speaker 2: It really is. And stretching out right in front of you,
[1:13] Speaker 2: carving this giant sweeping arc into the landscape, is a
[1:17] Speaker 2: massive crater rim. You, my friend, are standing in Jezero
[1:20] Speaker 2: Crater on Mars.
[1:20] Speaker 3: It's just incredible.
[1:21] Speaker 2: And specifically, you're standing on a stretch of rock that
[1:24] Speaker 2: kind of hugs the inner edge of this crater's rim.
[1:26] Speaker 2: It's this fascinating rugged area that geologists actually call the
[1:29] Speaker 2: margin unit.
[1:30] Speaker 3: Which is, I mean, without a doubt, one of the
[1:32] Speaker 3: most compelling pieces of real estate in the entire solar
[1:35] Speaker 3: system right now.
[1:36] Speaker 2: Oh, totally.
[1:36] Speaker 3: And the reason we're placing you there, right at the
[1:38] Speaker 3: edge of that invisible ancient shoreline, is because the very
[1:42] Speaker 3: ground beneath your boots, well, it shouldn't exist. Right.
[1:45] Speaker 2: It makes no sense.
[1:47] Speaker 3: None at all. It's completely the wrong rock in the
[1:49] Speaker 3: wrong place. And it's proving that everything we thought we
[1:52] Speaker 3: knew about the timeline of water and, you know, potentially
[1:55] Speaker 3: the timeline of life on early Mars... It's completely backwards.
[1:59] Speaker 2: It really is a massive plot twist. Because when you
[2:02] Speaker 2: picture Mars, you probably think of this dead static rock
[2:07] Speaker 2: floating in space.
[2:08] Speaker 3: A freezing, irradiated desert.
[2:10] Speaker 2: Exactly. Locked in this state of geological suspended animation for
[2:15] Speaker 2: literally billions of years. But by the time we finish
[2:17] Speaker 2: our conversation today, you're going to see it as a
[2:20] Speaker 2: world that was violently, vibrantly active.
[2:23] Speaker 3: Oh, incredibly active. We're talking about rushing water, intense internal heat,
[2:27] Speaker 3: and this incredibly complex chemistry.
[2:29] Speaker 2: And it all starts with a very reasonable expectation that
[2:32] Speaker 2: turned out to be just spectacularly wrong.
[2:34] Speaker 3: That really is the essence of planetary science, isn't it?
[2:37] Speaker 3: The universe just constantly humbles our assumptions.
[2:40] Speaker 2: It loves to prove us wrong.
[2:41] Speaker 3: It really does. So back in late 2023, when NASA's
[2:46] Speaker 3: Perseverance rover finally rolled up to this margin unit after
[2:50] Speaker 3: miles and miles of driving... The scientific community had a
[2:54] Speaker 3: very specific shopping list in mind.
[2:56] Speaker 2: They do exactly what they wanted.
[2:58] Speaker 3: Or so they thought. They were hunting for sedimentary rocks.
[3:02] Speaker 2: Which, if you think about it for a second, makes
[3:04] Speaker 2: perfect sense. If you were standing on the shoreline of
[3:06] Speaker 2: a lake, even if it's an ancient, dried up one,
[3:10] Speaker 2: you expect to find the things that lakes leave behind. Right.
[3:13] Speaker 2: On Earth, if you go to the mouth of the
[3:15] Speaker 2: Mississippi River or, you know, the shores of the Great Lakes,
[3:18] Speaker 2: what do you find?
[3:19] Speaker 3: Mud.
[3:19] Speaker 1: Sand.
[3:20] Speaker 3: Sand.
[3:21] Speaker 2: Exactly. You find sand, you find mud, you find silt.
[3:23] Speaker 2: Because over millennia, as water flows, it carries these tiny particles.
[3:29] Speaker 2: And as the water slows down, those particles settle.
[3:32] Speaker 3: They just drift down to the bottom.
[3:33] Speaker 2: Yeah, and they pile up layer upon layer upon layer.
[3:37] Speaker 2: And over unimaginable stretches of time, the immense pressure of
[3:41] Speaker 2: all those stacked layers basically compresses that mud and sand
[3:45] Speaker 2: into solid rock.
[3:46] Speaker 3: And that is sedimentary rock.
[3:48] Speaker 2: Exactly.
[3:49] Speaker 1: And.
[3:50] Speaker 3: From an astrobiological perspective, which is really the entire point
[3:53] Speaker 3: of the Perseverance mission, right? To search for ancient life
[3:57] Speaker 3: sedimentary rocks composed of clay and silt are the absolute
[4:02] Speaker 3: holy grail.
[4:02] Speaker 2: The jackpot.
[4:03] Speaker 3: Because they form so gradually, like layer by micro layer
[4:07] Speaker 3: in these gentle aquatic environments. They are incredible preservers of history. Right.
[4:11] Speaker 2: They're like a scrapbook. Every layer is a new page.
[4:14] Speaker 2: So if a microbe dies in a gently settling layer
[4:16] Speaker 2: of mud... It doesn't get crushed or incinerated. It just
[4:19] Speaker 2: gets entombed.
[4:20] Speaker 3: It's perfectly safe.
[4:21] Speaker 2: Yeah. Gets trapped in the organic material, protected, and eventually
[4:24] Speaker 2: turns to stone right along with the mud. So we
[4:27] Speaker 2: send this multi-billion dollar rover to the edge of an
[4:30] Speaker 2: ancient Martian lake.
[4:31] Speaker 3: Hoping to read that scrapbook.
[4:33] Speaker 2: Exactly. And the orbiters, looking down from space, they've been
[4:37] Speaker 2: bouncing signals off this specific area for years. And they
[4:41] Speaker 2: detected these massive signatures of carbonate minerals.
[4:44] Speaker 3: Which is a huge clue.
[4:46] Speaker 1: Huge!
[4:46] Speaker 2: Because on Earth, carbonates frequently form in shallow oceans and lakes,
[4:51] Speaker 2: like exactly the kind of environments that are just teeming
[4:54] Speaker 2: with life.
[4:55] Speaker 3: So everyone was ready.
[4:56] Speaker 2: Oh, the rover rolls up and everyone is practically rubbing
[5:00] Speaker 2: their hands together in anticipation. They are expecting to find
[5:03] Speaker 2: these beautiful, neat, easily readable layers of sedimentary rock.
[5:07] Speaker 3: But that is not what they found.
[5:09] Speaker 2: Not even close. They found igneous rock.
[5:12] Speaker 3: Precisely. And this is where the puzzle really takes shape,
[5:14] Speaker 3: because finding igneous rock sitting in what is undeniably an
[5:17] Speaker 3: ancient lake bed is, well, it's entirely counterintuitive.
[5:21] Speaker 2: It's just weird.
[5:22] Speaker 1: It is.
[5:22] Speaker 3: It fundamentally challenges the initial assumptions we derive from the
[5:26] Speaker 3: orbital data alone, because igneous rock forms from cooling magma
[5:30] Speaker 3: or surface volcanic activity.
[5:32] Speaker 2: Wait, let me push back on this for a second,
[5:34] Speaker 2: just to make sure I'm getting this right. Sure. Why
[5:36] Speaker 2: is finding igneous rock such a disappointment at first glance?
[5:40] Speaker 2: I mean... If igneous rock is basically frozen lava or magma,
[5:44] Speaker 2: doesn't that just mean a volcano erupted near the lake?
[5:47] Speaker 1: Well, yeah.
[5:48] Speaker 2: So doesn't that still give us a geological record?
[5:50] Speaker 3: It does give us a record, but it's the wrong
[5:53] Speaker 3: kind of record for what we were originally looking for.
[5:55] Speaker 3: Think about the environment required to make igneous rock in
[5:58] Speaker 3: the first place.
[5:59] Speaker 2: Okay.
[5:59] Speaker 3: It is incredibly hot, violently energetic, and completely sterile.
[6:04] Speaker 2: Ah, sterile.
[6:05] Speaker 3: You do not find delicate organic microbes perfectly preserved in
[6:09] Speaker 3: a flow of glowing 2,000 degree magma?
[6:12] Speaker 2: No, it would just incinerate everything.
[6:13] Speaker 3: Exactly. So if you're looking for this delicate biological scrapbook
[6:18] Speaker 3: built over millions of years by a gentle lake, finding
[6:21] Speaker 3: igneous rock is completely the wrong medium.
[6:24] Speaker 2: Okay, I see. Let's try an analogy for this. Imagine
[6:27] Speaker 2: you are an archivist, right? And you open up one
[6:30] Speaker 2: of those old dusty photo albums. fully expecting to find
[6:33] Speaker 2: a family scrapbook.
[6:34] Speaker 3: The sedimentary rock.
[6:36] Speaker 2: Yes, the sedimentary rock. You expect pages of pressed flowers,
[6:40] Speaker 2: little handwritten notes, train tickets carefully glued down over decades.
[6:44] Speaker 2: That's the delicate record of life you want.
[6:46] Speaker 3: Right.
[6:47] Speaker 2: But you open the album, and instead, there is just
[6:50] Speaker 2: a single, extremely high-resolution, flash-frozen photograph of a subterranean furnace.
[6:57] Speaker 3: That is the igneous rock.
[6:59] Speaker 2: Exactly. It an amazing photograph, But it's completely the wrong
[7:04] Speaker 2: thing for the container you found it in. It's like
[7:07] Speaker 2: opening one of those blue metal cookie tins, expecting cookies,
[7:09] Speaker 2: but finding sewing supplies instead.
[7:11] Speaker 3: Oh, I hate when that happens.
[7:12] Speaker 2: We've all been there. Except in this case, these sewing
[7:15] Speaker 2: supplies actually contain a map to buried treasure.
[7:18] Speaker 3: That is a brilliant way to conceptualize it. Because while
[7:20] Speaker 3: igneous rocks don't form by gently trapping mud and microbes,
[7:24] Speaker 3: they are the ultimate cosmic record keepers in a completely
[7:27] Speaker 3: different way.
[7:28] Speaker 2: How so?
[7:28] Speaker 3: Well, they're exactly like that high-resolution photograph you mentioned. When
[7:32] Speaker 3: magma cools, especially when it cools deep underground and crystallizes
[7:36] Speaker 3: into rock, the specific mineral crystals that form lock in
[7:40] Speaker 3: the exact details of the precise moment they solidified.
[7:43] Speaker 2: Oh, wow. So it's a snapshot.
[7:45] Speaker 3: A perfect snapshot. They capture the temperature, the ambient pressure,
[7:48] Speaker 3: the exact chemical composition of that subterranean environment. It's a
[7:52] Speaker 3: snapshot of the planet's internal chemistry.
[7:55] Speaker 2: And because they start out so chemically pristine, like so
[7:59] Speaker 2: untouched by... anything happening up on the surface like weather
[8:03] Speaker 2: or lakes, any chemical changes that happen to them after
[8:05] Speaker 2: they form are recorded really clearly, right?
[8:08] Speaker 3: Exactly. If water touches them later, it leaves a chemical stain,
[8:12] Speaker 3: so to speak.
[8:13] Speaker 2: But this brings up a massive logistical problem.
[8:15] Speaker 3: Which is?
[8:16] Speaker 2: If we are staring at rocks that form deep underground
[8:20] Speaker 2: in a place where a surface like used to be,
[8:22] Speaker 2: how do we even figure out what they're made of?
[8:24] Speaker 2: I mean, we can't exactly pack them up in a
[8:26] Speaker 2: FedEx box and ship them back to a lab on Earth.
[8:28] Speaker 3: No, we definitely can't. Not yet, anyway.
[8:30] Speaker 2: So what do we do?
[8:31] Speaker 3: Well, that brings us to one of the most extraordinary
[8:34] Speaker 3: pieces of technology ever sent to another planet. To read
[8:38] Speaker 3: the chemical diary locked inside this igneous rock, we need
[8:41] Speaker 3: a very specific kind of cosmic detective.
[8:45] Speaker 2: This is the part that absolutely blows my mind. I
[8:47] Speaker 2: want you to picture the Perseverance rover. It's roughly the
[8:51] Speaker 2: size of a small SUV. It has these six rugged wheels.
[8:56] Speaker 2: And sticking out from the front is this tall mast,
[8:59] Speaker 2: almost like a neck and a head.
[9:00] Speaker 3: Yeah, it looks very robotic.
[9:01] Speaker 2: It does. And perched right on top of that mast,
[9:05] Speaker 2: looking out over the Martian landscape, is an instrument called supercam.
[9:09] Speaker 3: Supercam is, honestly, it's nothing short of an engineering marvel.
[9:13] Speaker 3: Its primary job is to determine the mineralogy, so the
[9:17] Speaker 3: exact molecular chemical composition of the geologic features it is
[9:21] Speaker 3: looking at. And it does this based on the light
[9:24] Speaker 3: those features reflect.
[9:25] Speaker 2: But it doesn't just passively look, right, like a normal camera.
[9:29] Speaker 2: It interacts.
[9:30] Speaker 3: Oh, very much so.
[9:31] Speaker 2: Because when the team back on Earth spots an intriguing rock,
[9:34] Speaker 2: say a strange textured piece of bedrock jutting out of
[9:38] Speaker 2: the margin unit, they can send a command to Perseverance.
[9:40] Speaker 3: And the magic happens.
[9:41] Speaker 2: The rover turns its head, aims SuperCam, and fires a laser.
[9:45] Speaker 3: And we should be clear here. This isn't, you know,
[9:48] Speaker 3: a laser pointer used for a PowerPoint presentation.
[9:50] Speaker 2: Right, no.
[9:51] Speaker 3: We are talking about a highly complex pulsed laser capable
[9:55] Speaker 3: of hitting a target up to 21 feet away. That's
[9:58] Speaker 3: about six and a half meters.
[9:59] Speaker 2: Just pause and think about the sheer sci-fi reality of
[10:02] Speaker 2: this for a second. We have a robotic proxy built
[10:07] Speaker 2: by humans sitting in a dried up lake bed on
[10:10] Speaker 2: another planet shooting high powered lasers at rocks from 20
[10:14] Speaker 2: feet away.
[10:14] Speaker 3: It is pretty incredible.
[10:16] Speaker 2: It's insane. But how does shooting a rock tell you
[10:18] Speaker 2: what it's made of? When that laser hits the rock,
[10:22] Speaker 2: it doesn't just, like, warm it up, right? It physically
[10:25] Speaker 2: destroys a tiny portion of it.
[10:26] Speaker 3: Exactly. It vaporizes a tiny pinprick of the rock, turning
[10:30] Speaker 3: that microscopic amount of solid matter instantly into plasma.
[10:34] Speaker 2: Okay, hold on. Plasma. Break that down for me, because
[10:36] Speaker 2: that sounds like something out of a plasma rifle in
[10:38] Speaker 2: a video game.
[10:38] Speaker 3: It does sound like Halo or something. Yeah.
[10:40] Speaker 2: What actually happens to the rock in that fraction of
[10:42] Speaker 2: a second?
[10:43] Speaker 3: Well, when the laser pulses, it delivers an immense amount
[10:45] Speaker 3: of energy into a very, very small area. So the
[10:48] Speaker 3: rock instantly heats up to thousands of degrees. And the
[10:52] Speaker 3: atoms in the rock are essentially ripped apart. Their electrons
[10:55] Speaker 3: get so energized that they literally detach from their nuclei.
[10:59] Speaker 2: Okay.
[11:00] Speaker 3: And that soup of energized ions and electrons, that is plasma. Now,
[11:05] Speaker 3: nature abhors that kind of highly energized state.
[11:08] Speaker 2: He wants to settle down.
[11:09] Speaker 3: Exactly. Almost immediately, those electrons drop back down to their
[11:13] Speaker 3: normal energy levels. And when they drop back down, they
[11:16] Speaker 3: have to release that excess energy. And they do it
[11:19] Speaker 3: in the form of light. Ah.
[11:20] Speaker 2: So the rock literally flashes.
[11:22] Speaker 3: It does. It emits this tiny flash of light that
[11:26] Speaker 3: only lasts for a fraction of a second. But SuperCam
[11:28] Speaker 3: is waiting for it.
[11:29] Speaker 2: It's watching.
[11:30] Speaker 1: Yes.
[11:31] Speaker 3: Built into the instrument are these highly sensitive spectrometers. When
[11:35] Speaker 3: that rock is vaporized into plasma and emits that flash,
[11:38] Speaker 3: the spectrometers capture the light and analyze its spectrum.
[11:42] Speaker 2: OK, so it reads the light.
[11:43] Speaker 3: Right. And here's the key. Every single chemical element, iron, magnesium, carbon, oxygen,
[11:49] Speaker 3: they all emit a uniquely specific wavelength of light when
[11:52] Speaker 3: they're energized and drop back down.
[11:54] Speaker 2: Oh, that's so cool.
[11:55] Speaker 3: It is basically a chemical barcode. So by reading the
[11:59] Speaker 3: barcode of that tiny plasma flash, SuperCam can tell us
[12:03] Speaker 3: exactly what minerals are in that specific millimeter of rock.
[12:07] Speaker 2: It's completely wild. It is basically spectroscopy at a distance.
[12:11] Speaker 2: And the rover didn't just do this once as a
[12:12] Speaker 2: neat party trick, right?
[12:13] Speaker 3: Oh, no, not at all.
[12:15] Speaker 2: The data shows that Perseverance has analyzed more than 185
[12:18] Speaker 2: distinct bedrock targets across the margin unit using exactly this method.
[12:25] Speaker 3: 185 targets?
[12:27] Speaker 2: 185 individual laser strikes, vaporizing 185 tiny bits of rock
[12:32] Speaker 2: into plasma, reading 185 chemical barcodes.
[12:35] Speaker 3: It's a massive amount of data.
[12:37] Speaker 2: But wait, this is where I get a little stuck
[12:39] Speaker 2: on the methodology.
[12:40] Speaker 3: Okay, go ahead.
[12:41] Speaker 2: So 185 targets over a massive area. The rover isn't
[12:44] Speaker 2: just driving around a flat parking lot.
[12:46] Speaker 3: No, definitely not.
[12:47] Speaker 2: The margin unit is the rim of a crater. The
[12:49] Speaker 2: rover is driving up a massive slope. I mean, the
[12:52] Speaker 2: elevation change was something like 870 feet.
[12:54] Speaker 3: Yeah, it's a serious climb.
[12:56] Speaker 2: That's a climb equivalent to an 80-story skyscraper. If I
[12:59] Speaker 2: take a rock from the lobby of a skyscraper and
[13:01] Speaker 2: another rock from the roof, they have nothing to do
[13:03] Speaker 2: with each other.
[13:04] Speaker 3: So how do we string all those tiny plasma flashes together...
[13:08] Speaker 3: to tell a single coherent geological story over that kind
[13:14] Speaker 3: of massive vertical climb?
[13:15] Speaker 2: That is an excellent question. And it really gets to
[13:18] Speaker 2: the heart of how geologists read a landscape. Because they
[13:22] Speaker 2: aren't just collecting random rocks and throwing them in a pile.
[13:24] Speaker 3: Right.
[13:25] Speaker 2: By mapping those 185 precise data points across that 870-foot climb,
[13:31] Speaker 2: the researchers were able to create what we call a
[13:33] Speaker 2: mineralogical gradient.
[13:35] Speaker 3: A gradient. So like watching how things change step by step.
[13:38] Speaker 2: Exactly. Because this rock all belongs to the same continuous
[13:41] Speaker 2: geological formation, the margin unit, the changes in chemistry aren't
[13:45] Speaker 2: just random. Okay. They track exactly how the rocks have
[13:49] Speaker 2: been altered in relation to their height on the crater rim.
[13:52] Speaker 2: As the rover climbs up the slope away from the
[13:54] Speaker 2: basin of the lake bed, the chemistry changes in a
[13:57] Speaker 2: very predictable, trackable way.
[13:59] Speaker 3: I see.
[14:00] Speaker 2: They track the alterations from the top of the hill,
[14:02] Speaker 2: down the slope, and deep into the basin where the
[14:04] Speaker 2: lake used to be. Okay, that makes perfect sense. So
[14:08] Speaker 2: the higher you go on this 80-story climb, the further
[14:10] Speaker 2: you get from where the water of the lake would
[14:12] Speaker 2: have been resting.
[14:13] Speaker 3: Exactly.
[14:14] Speaker 2: And the lower you go, the deeper into the aquatic
[14:16] Speaker 2: history you dive.
[14:17] Speaker 3: Oh.
[14:18] Speaker 2: But before we can talk about the water that altered
[14:20] Speaker 2: these rocks down below, we have to look at the
[14:22] Speaker 2: starting point, right?
[14:23] Speaker 3: We do.
[14:24] Speaker 2: We have to look at the blank canvas that SuperCam
[14:26] Speaker 2: discovered at the very top of that 870-foot elevation at
[14:30] Speaker 2: the absolute peak of the climb.
[14:32] Speaker 3: And that blank canvas is breathtaking, honestly, because it provides
[14:36] Speaker 3: a window into... Deep time on Mars.
[14:39] Speaker 2: Deep time. I love that phrase.
[14:41] Speaker 3: It's very evocative. When Perseverance fired its laser at the
[14:45] Speaker 3: highest elevations of the margin unit, the rocks it analyzed
[14:49] Speaker 3: were completely distinct from the rocks lower down.
[14:51] Speaker 2: How so?
[14:52] Speaker 3: They were coarse-grained, and they were highly crystalline.
[14:56] Speaker 2: And crucially, the chemical barcode from the laser showed almost
[14:59] Speaker 2: zero trace of alteration. Like, there were no chemical stains
[15:02] Speaker 2: from water. This was virgin, untouched rock.
[15:05] Speaker 3: Exactly. Exactly. The dominant mineral at this high elevation is
[15:08] Speaker 3: called olivine. Yeah, olivine is an igneous mineral made primarily
[15:13] Speaker 3: of magnesium and iron silicate. Now, the physical structure of
[15:17] Speaker 3: this olivine, the way it actually looks, tells us an
[15:20] Speaker 3: enormous amount about its origin story.
[15:22] Speaker 2: Right, because of the crystals.
[15:23] Speaker 3: Yes. The fact that the grains are coarse and large
[15:27] Speaker 3: means that it formed in a body of magma deep underground.
[15:31] Speaker 2: Let me jump in here with an analogy because this
[15:33] Speaker 2: part is just fascinating to me.
[15:34] Speaker 3: Please do.
[15:36] Speaker 2: Have you ever tried making rock candy?
[15:38] Speaker 3: Oh, yeah, when I was a kid. Right.
[15:39] Speaker 2: So you dissolve a ton of sugar in boiling water,
[15:43] Speaker 2: and then you let it cool. Now, if you take
[15:46] Speaker 2: that hot sugar water and put it straight in the
[15:47] Speaker 2: freezer to cool it really, really fast, you get these tiny,
[15:51] Speaker 2: almost microscopic crystals.
[15:53] Speaker 3: Yeah, it gets all cloudy and brittle.
[15:54] Speaker 2: Exactly. It's just a mess. But if you leave it
[15:57] Speaker 2: on the counter and let it cool incredibly slowly over
[16:00] Speaker 2: days and days, the sugar molecules have time to slowly
[16:04] Speaker 2: find each other And perfectly aligned.
[16:06] Speaker 3: And you get those massive, beautiful crystals.
[16:08] Speaker 2: They're massive, distinct, chunky crystals.
[16:11] Speaker 3: Well, that is the exact thermodynamic mechanism at play with
[16:14] Speaker 3: this Martian olivine. Because the grains are so large and coarse,
[16:18] Speaker 3: we know definitively that this magma cooled incredibly slowly.
[16:22] Speaker 2: And the only way magma cools slowly is if it's
[16:24] Speaker 2: heavily insulated, right?
[16:26] Speaker 3: Exactly. This wasn't a volcano that erupted lava onto the
[16:29] Speaker 3: surface to cool quickly in the freezing Martian air.
[16:31] Speaker 2: That would be the freezer rock candy. Right.
[16:33] Speaker 3: This was a subterranean magma chamber insulated by miles and
[16:37] Speaker 3: miles of Martian crust above it that very slowly crystallized
[16:41] Speaker 3: into solid rock over thousands, perhaps millions of years.
[16:45] Speaker 2: That is just wild to picture. So we have this
[16:48] Speaker 2: pristine rock candy like olivine sitting deep, deep underground in
[16:52] Speaker 2: the crust. But today, Perseverance is driving over it on
[16:56] Speaker 2: the surface.
[16:56] Speaker 3: Yes, it is.
[16:58] Speaker 2: How did a subterranean magma chamber become a surface rock?
[17:01] Speaker 3: Erosion. Relentless eons-long erosion.
[17:04] Speaker 2: Just weathering away.
[17:05] Speaker 3: Yeah, and this is what really sets the stage for
[17:07] Speaker 3: the true scale of geological time we're talking about here.
[17:10] Speaker 3: After this magma cooled into solid olivine deep in the crust,
[17:13] Speaker 3: the planet went to work. Over billions of years, relentless wind,
[17:18] Speaker 3: perhaps early-flowing surface water— And the slow grinding away of
[17:22] Speaker 3: the landscape completely eroded away all the ground that sat
[17:25] Speaker 3: above it.
[17:26] Speaker 2: It just stripped the roof off.
[17:27] Speaker 3: Exactly. Imagine miles of solid rock just turning to dust
[17:32] Speaker 3: and blowing away. The ceiling was entirely removed, exposing this
[17:36] Speaker 3: deep underground rock to the open air.
[17:38] Speaker 2: That is staggering to think about, just miles of rock
[17:41] Speaker 2: blowing away in the wind. So this Halloween is basically
[17:44] Speaker 2: our baseline. It's the before picture in our geological makeover montage.
[17:48] Speaker 3: That's a good way to put it.
[17:49] Speaker 2: But once this deep underground rock was finally exposed to
[17:52] Speaker 2: the elements, Mars didn't just give it a gentle splash
[17:55] Speaker 2: of water.
[17:56] Speaker 3: No, it did not.
[17:57] Speaker 2: It subjected this rock to a highly complex, multi-stage aquatic assault.
[18:02] Speaker 2: And the story starts with a very specific, almost sneaky
[18:05] Speaker 2: type of water.
[18:06] Speaker 3: Sneaky is right.
[18:07] Speaker 2: Because we're not talking about a lake raining down from above,
[18:09] Speaker 2: but groundwater sneaking up from below.
[18:11] Speaker 3: Yes. And based on that careful mineralogical gradient mapped by SuperCam,
[18:16] Speaker 3: we can definitively identify this as the first major episode
[18:19] Speaker 3: of water interaction. And it fundamentally altered the physical landscape
[18:24] Speaker 3: that the rover sees today.
[18:26] Speaker 2: So let's explore this first episode, the carbon dioxide groundwater.
[18:31] Speaker 2: What happens when this pristine, deep-earth olivine finally meets water
[18:35] Speaker 2: for the very first time?
[18:37] Speaker 3: Well, the first interaction wasn't with fresh, pure water. Right.
[18:40] Speaker 3: It was with groundwater that was incredibly rich in carbon dioxide.
[18:45] Speaker 3: This CO2-rich groundwater seeped up from deep within the planet
[18:49] Speaker 3: and infiltrated the fractures and cracks within the olivine bedrock
[18:52] Speaker 3: at the lower elevations of the unit.
[18:54] Speaker 2: Okay, so imagine this massive expanse of solid crystalline rock.
[18:59] Speaker 2: The ground naturally shifts over millions of years, maybe meteorite
[19:03] Speaker 2: impacts happen nearby, and the rock just naturally cracks and fractures.
[19:06] Speaker 3: Exactly, it breaks up a bit.
[19:08] Speaker 2: And then Creeping up through those microscopic veins and larger
[19:11] Speaker 2: fissures comes this highly carbonated water. It errs like the
[19:16] Speaker 2: planted underground plumbing system just backed up into the basement.
[19:19] Speaker 3: That's exactly what happened. And when that CO2-rich groundwater hit
[19:23] Speaker 3: the olivine, a really powerful chemical reaction took place.
[19:26] Speaker 2: What kind of reaction?
[19:27] Speaker 3: The water didn't just passively wet the rock. It chemically
[19:30] Speaker 3: attacked the olivine, immediately touching the water inside those cracks
[19:34] Speaker 3: and transforming the magnesium and iron into carbonate minerals.
[19:38] Speaker 1: Ooh!
[19:39] Speaker 2: This is where the orbital data from the satellites comes
[19:42] Speaker 2: back into play.
[19:43] Speaker 3: Yes.
[19:43] Speaker 2: Because remember, before they even landed the rover, the satellites
[19:46] Speaker 2: orbiting Mars saw huge signatures of carbon from space.
[19:50] Speaker 3: They did.
[19:51] Speaker 2: And the scientists initially thought, uh-huh, carbonates, a giant lake.
[19:57] Speaker 2: But that's not what SuperCam found on the ground at all.
[19:59] Speaker 3: Exactly. The dominant hypothesis before landing was that this massive
[20:03] Speaker 3: carbonate signature seen from orbit formed through a top-down interaction
[20:08] Speaker 3: with the lake water.
[20:09] Speaker 2: Like it settled from above.
[20:10] Speaker 3: Right. But the on-the-ground reality, the microscopic reality revealed by
[20:15] Speaker 3: the lasers, showed that the carbonate was intensely localized.
[20:19] Speaker 2: Localized how?
[20:20] Speaker 3: It was locked inside these distinct narrow ridges formed by
[20:23] Speaker 3: the groundwater seeping up from below. not a lake settling
[20:26] Speaker 3: from above.
[20:27] Speaker 2: Okay, let's talk about those ridges because this is where
[20:29] Speaker 2: the geology gets intensely visual for the listener.
[20:32] Speaker 3: It's very strict.
[20:33] Speaker 2: It really is.
[20:33] Speaker 3: Yeah.
[20:34] Speaker 2: When you look at the raw images beamed back from
[20:36] Speaker 2: Perseverance in this area, you don't just see a flat,
[20:39] Speaker 2: cracked surface.
[20:40] Speaker 3: No.
[20:41] Speaker 2: You see these strange, raised ridges crisscrossing the rock, sticking
[20:46] Speaker 2: up into the air like veins popping out of the
[20:48] Speaker 2: back of a hand. Why do they stand up like
[20:50] Speaker 2: that if they formed inside flat cracks?
[20:53] Speaker 3: It comes down to a process called differential erosion.
[20:56] Speaker 2: Differential erosion.
[20:57] Speaker 3: Okay. The chemical reaction that occurred inside the fractures, that
[21:01] Speaker 3: transformation of olivine into carbonate we just talked about, it
[21:04] Speaker 3: created a material that is significantly harder and much more
[21:08] Speaker 3: resistant to weathering than the original unaltered olivine surrounding it.
[21:12] Speaker 2: Okay, wait. I have an analogy for this. Think of
[21:15] Speaker 2: it like a freshly baked chocolate chip cookie left out
[21:17] Speaker 2: in a windstorm.
[21:18] Speaker 3: A windstorm. Okay, I'm with you.
[21:20] Speaker 2: Over time, the soft, Crumbly dough of the cookie, which
[21:24] Speaker 2: represents the original olivine, is going to erode and blow away.
[21:27] Speaker 3: Right. The wind takes it.
[21:28] Speaker 2: But those hard, dense chocolate chips, which are the carbonate
[21:31] Speaker 2: that formed inside the cracks, they're going to resist the wind.
[21:35] Speaker 3: Because they're tougher.
[21:36] Speaker 2: Exactly. Eventually, the soft cookie dough wears away completely, and
[21:41] Speaker 2: you're left with just the hard chocolate chips standing upright,
[21:44] Speaker 2: mapping out exactly where they used to sit inside the dough.
[21:47] Speaker 3: That is a perfect visualization. Because over millions and millions
[21:51] Speaker 3: of years, the softer olivine rock wore away, leaving the harder,
[21:55] Speaker 3: carbonate-filled fractures standing proud of the surface as these intricate
[22:00] Speaker 3: raised ridges.
[22:01] Speaker 2: It's so cool.
[22:02] Speaker 3: It is. It is literally a ghostly physical imprint of
[22:06] Speaker 3: a groundwater system that flowed billions of years ago.
[22:09] Speaker 2: So groundwater sneaks up. chemically alters the rock from below
[22:12] Speaker 2: and leaves these hardened veins behind.
[22:15] Speaker 3: Yes.
[22:15] Speaker 2: But what about the massive body of water that actually
[22:18] Speaker 2: sat on top of all this, the actual lake that
[22:20] Speaker 2: made Jezero Crater famous in the first place? If we're
[22:23] Speaker 2: standing in a lake bed, where's the evidence of the lake?
[22:25] Speaker 3: That brings us to the second distinct episode of Water Interaction.
[22:29] Speaker 2: Episode two.
[22:30] Speaker 3: Right. And this one is intimately tied to the ancient
[22:32] Speaker 3: lake itself. As Perseverance moved lower down the crater rim,
[22:35] Speaker 3: definitively crossing below what would have been the ancient waterline,
[22:39] Speaker 3: the chemical stories shifted dramatically.
[22:41] Speaker 2: So below this invisible ancient water line, what did SuperCam
[22:46] Speaker 2: see that was different from the carbonate ridges formed by
[22:49] Speaker 2: the groundwater?
[22:50] Speaker 3: Well, lower in the unit, on the actual floor of
[22:52] Speaker 3: the lake bed, the rock looks visibly transformed in a
[22:56] Speaker 3: totally different way.
[22:57] Speaker 2: How so?
[22:58] Speaker 3: The coarse olivine grains are highly fractured and degraded, but
[23:02] Speaker 3: the crucial detail is what is sitting between those fractured grains.
[23:06] Speaker 3: SuperCam detected massive spikes of silica.
[23:09] Speaker 2: Okay, silica. Why is silica the smoking gun for a lake?
[23:12] Speaker 3: It's basic chemistry. When you take olivine magnesium iron silicate
[23:17] Speaker 3: and you subject it to prolonged water exposure to form carbonate,
[23:21] Speaker 3: the chemical equation has to balance.
[23:22] Speaker 1: Right.
[23:22] Speaker 2: You can't just lose atoms.
[23:24] Speaker 3: Exactly. The process of pulling the magnesium and iron out
[23:27] Speaker 3: to make carbonate naturally leaves the silicate behind as a
[23:30] Speaker 3: residual byproduct.
[23:31] Speaker 2: Oh, I see.
[23:32] Speaker 3: Yeah, it forms concentrated silica.
[23:34] Speaker 1: But wait, wait.
[23:34] Speaker 2: If groundwater also made carbonate, wouldn't it also leave silica?
[23:38] Speaker 2: Why does silica prove the lake was there?
[23:41] Speaker 3: Ah, it's the spatial distribution that matters here. The rover
[23:44] Speaker 3: didn't just find a little silica everywhere.
[23:46] Speaker 2: Right, because they mapped the gradient.
[23:48] Speaker 3: Precisely. They mapped it. And they found that the silica
[23:51] Speaker 3: concentration spikes massively, specifically in the rocks that sat beneath
[23:55] Speaker 3: the waterline. The fact that the silica footprint gets heavier
[23:59] Speaker 3: the lower you go confirms that the standing body of water,
[24:02] Speaker 3: the lake itself, had a direct, broad, and prolonged chemical
[24:07] Speaker 3: interaction with this igneous canvas.
[24:09] Speaker 2: So the lake wasn't just, like, a puddle on top.
[24:13] Speaker 3: No, the lake didn't just sit there passively. Its water
[24:16] Speaker 3: penetrated the bedrock, further altering the olivine, driving more of
[24:20] Speaker 3: that carbonate-forming reaction across a wide area, and leaving a massive,
[24:25] Speaker 3: undeniable footprint of silica behind.
[24:27] Speaker 2: Okay, I have to stop and push back on this
[24:29] Speaker 2: timeline a bit, because this is bothering me.
[24:31] Speaker 3: Okay, what's bothering you?
[24:32] Speaker 2: If the first episode was groundwater seeping up, And the
[24:34] Speaker 2: second episode was a massive lake sitting on top. How
[24:38] Speaker 2: do we know they didn't happen at the exact same time?
[24:40] Speaker 3: That's a fair question.
[24:41] Speaker 2: I mean, every lake on Earth has groundwater beneath it.
[24:43] Speaker 2: They're part of the same system. So why are these
[24:46] Speaker 2: considered two distinct, separate geological events?
[24:50] Speaker 3: That is a vital point of clarification. And it really
[24:53] Speaker 3: gets to the limits of what a rover can actually do.
[24:56] Speaker 3: When geologists look at these rocks with SuperCam... They are
[24:59] Speaker 3: reading relative time, not absolute time.
[25:02] Speaker 2: Relative time.
[25:03] Speaker 3: Meaning we cannot yet point a laser and say the
[25:06] Speaker 3: groundwater bubbled up on a Tuesday 3.4 billion years ago
[25:10] Speaker 3: and the lake formed exactly one million years later.
[25:13] Speaker 2: Right. We don't have a calendar.
[25:14] Speaker 3: Exactly. What the team can do, though.
[25:22] Speaker 2: Looking at how the physical structures overlap.
[25:25] Speaker 3: Exactly. Like looking at footprints in dried mud.
[25:27] Speaker 2: Oh, I like that.
[25:28] Speaker 3: Yeah, if you see a dog footprint stamped directly over
[25:31] Speaker 3: a human boot print, breaking the ridges of the boot print,
[25:36] Speaker 3: you know, with absolute certainty the boot was there first.
[25:38] Speaker 2: Right.
[25:38] Speaker 3: Even if you don't know exactly what year either of
[25:41] Speaker 3: them walked by.
[25:41] Speaker 2: I see. So the carbonate ridges from the groundwater are
[25:45] Speaker 2: the boot prints. They display physical characteristics that suggest they
[25:49] Speaker 2: were fully formed before the broader silica-leaving alteration caused by
[25:54] Speaker 2: the lake water came along and stamped right over them.
[25:57] Speaker 3: Precisely. The lake alteration cuts across the features formed by
[26:02] Speaker 3: the groundwater. However, the exact absolute age or the length
[26:07] Speaker 3: of the gap in time between the groundwater phase and
[26:09] Speaker 3: the lake phase, well, that remains a mystery.
[26:12] Speaker 2: It could have been quick or it could have been ages.
[26:14] Speaker 3: It could have been 10,000 years. It could have been
[26:16] Speaker 3: 10 million years. We can't solve that just by shooting
[26:20] Speaker 3: lasers from a rover. That will actually require bringing the
[26:23] Speaker 3: physical samples back to Earth.
[26:25] Speaker 2: Got it. So it's a relative timeline. First came the
[26:27] Speaker 2: CO2 groundwater from below, cracking the rock and leaving ridges.
[26:31] Speaker 2: Then eventually came the massive lake from above, soaking the
[26:34] Speaker 2: bedrock and leaving this thick blanket of silica.
[26:37] Speaker 3: Exactly.
[26:38] Speaker 2: Now, you would think a giant lake drying up would
[26:40] Speaker 2: be the grand finale of this story.
[26:42] Speaker 3: You would think so.
[26:43] Speaker 2: The water evaporates. The planet loses its atmosphere. Everything freezes solid.
[26:47] Speaker 2: End of story. Roll credits.
[26:49] Speaker 3: But Mars wasn't done.
[26:50] Speaker 2: No, Mars wasn't done. The eastern part of the margin
[26:54] Speaker 2: unit held one final place. Very hot surprise.
[26:58] Speaker 3: And this final surprise really forces us to rethink the
[27:01] Speaker 3: entire timeline of Martian planetary death.
[27:03] Speaker 2: Yeah.
[27:04] Speaker 3: It paints a picture of a planet that remained intensely
[27:07] Speaker 3: geologically active much later than we ever assumed.
[27:10] Speaker 2: Let's talk about what they found in the eastern part
[27:12] Speaker 2: of the unit. Because the rover stumbled onto something totally
[27:15] Speaker 2: different over there.
[27:16] Speaker 3: Yeah. As Perseverance explored the eastern margin unit, it encountered
[27:20] Speaker 3: a specific zone where it discovered thick, prominent mineral veins
[27:24] Speaker 3: cutting through the rock.
[27:26] Speaker 2: Like the ridges?
[27:27] Speaker 3: No, these aren't microscopic cracks like the ones the groundwater
[27:30] Speaker 3: seeped through. We are talking about massive veins roughly 10
[27:35] Speaker 3: inches or 25 centimeters thick.
[27:37] Speaker 2: Oh, well, 10 inches thick.
[27:38] Speaker 3: Yeah, they're substantial. And the chemistry of these veins, again,
[27:41] Speaker 3: read by SuperCam, was completely alien to the carbonate and
[27:45] Speaker 3: silica we discussed earlier.
[27:46] Speaker 2: What were they made of?
[27:47] Speaker 3: These veins are composed of minerals like calcium sulfate and, crucially, fluorite.
[27:52] Speaker 2: Okay, fluorite. I know fluorite's a beautiful crystal on Earth.
[27:55] Speaker 2: But why is it the smoking gun for this third
[27:59] Speaker 2: water episode?
[27:59] Speaker 3: Because on Earth, fluoride is a mineral that forms under
[28:03] Speaker 3: very specific extreme conditions. It typically crystallizes when extremely hot,
[28:09] Speaker 3: highly mineralized water circulates rapidly through fractures in volcanic rocks.
[28:14] Speaker 3: We are talking about high temperature hydrothermal conditions.
[28:18] Speaker 2: Hydrothermal, like the boiling vents you see at the bottom
[28:20] Speaker 2: of the ocean. Or the geysers in Yellowstone.
[28:22] Speaker 3: Exactly like that.
[28:23] Speaker 2: So finding fluorite means we aren't just talking about cold
[28:26] Speaker 2: groundwater creeping up or a tepid, tranquil surface lake gently
[28:30] Speaker 2: soaking into the dirt. We are talking about boiling, chemically
[28:33] Speaker 2: charged water surging violently through the crust.
[28:36] Speaker 3: Yes. And the presence of these massive hydrothermal veins implies
[28:41] Speaker 3: something profound.
[28:42] Speaker 2: What does it imply?
[28:43] Speaker 3: It means that long after the initial groundwater phase and
[28:46] Speaker 3: long after the surface lake had completely dried up, there
[28:48] Speaker 3: was a completely separate later geological event.
[28:51] Speaker 2: A whole new phase.
[28:52] Speaker 3: Yeah. This specific area experienced a massive surge of heated
[28:56] Speaker 3: underground water.
[28:57] Speaker 2: It's like digging into the walls of an ancient Roman
[29:00] Speaker 2: ruin and finding a perfectly intact modern hot water pipe
[29:06] Speaker 2: retrofitted right into the stone.
[29:08] Speaker 3: That's a great way to think of it.
[29:09] Speaker 2: You have this incredibly old structure, the original olivine that
[29:12] Speaker 2: was altered by the ancient lake. And then you have
[29:14] Speaker 2: this aggressive later addition that proves there was a whole
[29:18] Speaker 2: secondary era of intense boiling activity long after the main
[29:23] Speaker 2: event of the lake was over.
[29:24] Speaker 3: The implications of that retrofitted pipe are just staggering.
[29:28] Speaker 2: Because it means it wasn't dead.
[29:29] Speaker 3: Exactly. It means Mars was not simply a world that
[29:32] Speaker 3: lost its magnetic field, lost its atmosphere, dried up and
[29:36] Speaker 3: immediately went geologically dead.
[29:38] Speaker 2: Right.
[29:39] Speaker 3: The presence of these late-stage hydrothermal veins proves that the
[29:42] Speaker 3: planet retained significant internal heat and maintained a highly dynamic,
[29:47] Speaker 3: active underground plumbing system long after the surface conditions had
[29:51] Speaker 3: become a frozen wasteland.
[29:52] Speaker 2: That is just incredible. So if we pull all of
[29:54] Speaker 2: this together, we've tracked three incredibly distinct water events that
[29:58] Speaker 2: in this one relatively small stretch of a crater rim.
[30:01] Speaker 3: Three very different events.
[30:03] Speaker 2: First, the stealthy CO2 groundwater bubbling up. Second, the massive
[30:08] Speaker 2: surface lake soaking down into the bedrock. And third, the
[30:12] Speaker 2: violent injection of boiling hot hydrothermal veins.
[30:15] Speaker 3: It truly is a crossroads of entirely different aquatic systems.
[30:18] Speaker 2: It really is.
[30:19] Speaker 3: Yeah.
[30:20] Speaker 2: But this brings us to the ultimate question, doesn't it?
[30:22] Speaker 3: It does.
[30:23] Speaker 2: The reason we are spending billions of dollars and decades
[30:27] Speaker 2: of human effort to shoot lasers at rocks on a
[30:31] Speaker 2: freezing desert planet millions of miles away.
[30:34] Speaker 3: The big question.
[30:35] Speaker 2: What does all of this incredibly complex plumbing mean for
[30:38] Speaker 2: the search for life?
[30:39] Speaker 3: This is the moment where all the geological and chemical
[30:42] Speaker 3: puzzle pieces we've discussed suddenly snap together to form a
[30:45] Speaker 3: profoundly exciting astrobiological picture.
[30:48] Speaker 2: Okay, let's look at the big picture. Lay it out
[30:50] Speaker 2: for me. All right.
[30:50] Speaker 3: Earlier, we established that Jezero Crater sits inside one of
[30:53] Speaker 3: the largest exposures of carbonate on Mars.
[30:55] Speaker 2: Right, the chocolate chips. Right.
[30:57] Speaker 3: And we talked about how carbonate, along with silica, are
[31:00] Speaker 3: vital signposts in the search for ancient life because they
[31:03] Speaker 3: are exceptional at locking in and fossilizing traces of microscopic life.
[31:08] Speaker 2: They entomb things perfectly.
[31:10] Speaker 3: But the true magic of this location isn't just about preservation.
[31:14] Speaker 2: It's not.
[31:14] Speaker 3: No, it's about creation.
[31:15] Speaker 2: Oh, creation.
[31:16] Speaker 3: Yeah.
[31:16] Speaker 2: Right, because this wasn't just a place where microbes could
[31:19] Speaker 2: survive if they happened to wash in on a river.
[31:21] Speaker 1: Mm-hmm.
[31:21] Speaker 2: The geology itself was actively cooking up a feast for them.
[31:25] Speaker 3: Exactly. When water, any kind of water, be it groundwater,
[31:29] Speaker 3: lake water, or hydrothermal fluid interacts with olivine, a very
[31:33] Speaker 3: specific chemical reaction occurs.
[31:35] Speaker 2: Okay, what happens?
[31:37] Speaker 3: As the water strips the magnesium and iron out of
[31:39] Speaker 3: the olivine to create the carbonate and silica, that molecular
[31:42] Speaker 3: shuffling fundamentally releases hydrogen gas as a byproduct.
[31:46] Speaker 2: Okay, stop right there. Hydrogen gas. Why is hydrogen the
[31:50] Speaker 2: key here?
[31:50] Speaker 3: Because hydrogen is a primary, incredibly potent food source for
[31:55] Speaker 3: many types of primitive microbes.
[31:58] Speaker 2: Wait, hold on. Chemolitho what? I've heard of phogosynthesis, where
[32:02] Speaker 2: plants eat sunlight. But how does something eat hydrogen? Break
[32:05] Speaker 2: that down for me. Are these things that eat rock
[32:07] Speaker 2: instead of sunlight?
[32:08] Speaker 3: Exactly. On Earth, we call them chemolithoautotrophs.
[32:11] Speaker 2: Chemolithoautotrophs.
[32:12] Speaker 3: Okay. Yeah, it's a mouthful. Chemo for chemical, litho for rock,
[32:17] Speaker 3: autotroph for self-feeding.
[32:18] Speaker 2: Self-feeding rock chemicals. Got it.
[32:20] Speaker 3: These are organisms that do not need sunlight or complex
[32:23] Speaker 3: organic matter to survive. They literally extract energy from the
[32:27] Speaker 3: chemical reactions happening between rocks and water.
[32:30] Speaker 2: That is wild.
[32:31] Speaker 3: It is. Deep underground on Earth, or at the bottom
[32:34] Speaker 3: of the pitch black ocean, these microbes thrive purely on
[32:37] Speaker 3: the hydrogen released by the exact same olivine water reactions
[32:41] Speaker 3: we just described on Mars.
[32:42] Speaker 2: That is unbelievable. So early Mars was basically setting an
[32:46] Speaker 2: endless table.
[32:47] Speaker 3: A literal buffet.
[32:48] Speaker 2: If we synthesize all of this, the margin unit is
[32:51] Speaker 2: the ultimate jackpot for astrobiology.
[32:54] Speaker 3: It really is.
[32:55] Speaker 2: You have a deep-seated, aeneas rock composed of olivine. You
[32:58] Speaker 2: have a massive, continuous influx of water from multiple sources
[33:02] Speaker 2: over a vast expanse of time-ground water, lakes, boiling vents.
[33:06] Speaker 3: All hitting the rock. Right.
[33:08] Speaker 2: And the chemical reaction between that water and that rock
[33:11] Speaker 2: actively produces hydrogen, creating a literal self-sustaining food source for
[33:15] Speaker 2: potential microbial life. It's a micro buffet.
[33:18] Speaker 3: It is a micro buffet operated by the planet itself.
[33:22] Speaker 3: The geology was pumping out the food, the hydrogen, while
[33:26] Speaker 3: simultaneously producing the exact minerals, the silica and the carbonate
[33:30] Speaker 3: that are perfectly suited to fossilize and preserve those very
[33:34] Speaker 3: same microbes for us to find billions of years later.
[33:38] Speaker 2: It's a closed loop.
[33:39] Speaker 3: It is the perfect convergence of habitability and preservation potential.
[33:43] Speaker 2: It's like finding a restaurant that not only cook your
[33:45] Speaker 2: favorite meal. but also perfectly taxidermies you after you eat
[33:49] Speaker 2: it so you can be studied forever.
[33:51] Speaker 3: Well, a slightly macabre analogy, but geologically accurate.
[33:56] Speaker 2: I try.
[33:56] Speaker 3: Because this area is one of the largest carbonate exposures
[33:59] Speaker 3: on the planet, understanding the mechanics of how it formed
[34:02] Speaker 3: here gives us a key for understanding the habitability of
[34:05] Speaker 3: early Mars as a whole.
[34:07] Speaker 2: It really reinforces the idea that you just cannot look
[34:09] Speaker 2: at pictures from space and claim to understand a planet.
[34:12] Speaker 3: Absolutely not.
[34:13] Speaker 2: The orbiter saw carbonate in said lake. But the reality
[34:16] Speaker 2: was infinitely more complex.
[34:18] Speaker 3: Exactly. After over a decade of operating advanced Mars rovers,
[34:23] Speaker 3: the lesson is overwhelmingly clear. Orbital data almost never tells
[34:29] Speaker 3: the full, nuanced story.
[34:31] Speaker 2: You only get the broad strokes.
[34:32] Speaker 3: Right. You can see the broad strokes from orbit. You
[34:34] Speaker 3: can see the colors and the shapes. But to truly
[34:36] Speaker 3: reconstruct the changing climate, the intricate plumbing, and the history
[34:40] Speaker 3: of habitability, you have to get wheels on the ground.
[34:44] Speaker 2: You need to be there.
[34:44] Speaker 3: You have to get close enough to shoot lasers at
[34:47] Speaker 3: the rocks and read their chemical diaries molecule by molecule.
[34:51] Speaker 2: It is just breathtaking to think about. You start with
[34:53] Speaker 2: this barren, dusty, rusty landscape. It looks totally dead. But
[34:58] Speaker 2: by simply reading the chemistry of the rocks with a laser,
[35:01] Speaker 2: you uncover this incredibly violent, wet, hot, dynamic, life-sustaining history.
[35:06] Speaker 3: And it leaves us with profound questions, doesn't it? Not
[35:09] Speaker 3: just about the history of Mars, but about our own
[35:10] Speaker 3: place in the solar system and the origins of life itself.
[35:14] Speaker 2: Which brings me to a final, slightly mind-bending thought for
[35:17] Speaker 2: you to ponder.
[35:17] Speaker 3: Oh, I love these.
[35:18] Speaker 2: We've just spent all this time talking about how early
[35:21] Speaker 2: Mars had this incredibly complex, multi-stage history. Water interacting with
[35:26] Speaker 2: deep underground igneous rocks, stripping up the iron, creating hydrogen buffets,
[35:31] Speaker 2: and eventually firing up hot hydrothermal vents. Right. We know
[35:35] Speaker 2: from biology that this creates the absolute perfect conditions for
[35:38] Speaker 2: life to begin.
[35:39] Speaker 3: It's the perfect recipe.
[35:41] Speaker 2: But now, consider Earth. Earth is geologically hyperactive. Our tectonic
[35:45] Speaker 2: plates are constantly grinding together, recycling our crust, melting it
[35:49] Speaker 2: down into the mantle, and entirely destroying our earliest rocks.
[35:52] Speaker 3: We constantly pave over our own history.
[35:55] Speaker 2: Exactly. We have almost zero physical record of what the
[35:58] Speaker 2: exact conditions were like on Earth when life first sparked.
[36:01] Speaker 2: The evidence has literally been swallowed by the planet.
[36:04] Speaker 3: Which is incredibly frustrating for geologists.
[36:06] Speaker 2: But right next door, here is this dry, desolate, frozen
[36:10] Speaker 2: crater on Mars... perfectly preserving a 4 billion-year-old snapshot of
[36:14] Speaker 2: hydrothermal vents and hydrogen-producing rocks.
[36:17] Speaker 3: It's just sitting there waiting.
[36:18] Speaker 2: So, could this complex chemistry we see on Mars perfectly
[36:22] Speaker 2: mirror how life originated on our own planet?
[36:25] Speaker 3: It's a profound thought.
[36:27] Speaker 2: Is it possible that by staring into the freezing dust
[36:30] Speaker 2: of Jezero Crater, we aren't just looking for Martian microbes?
[36:34] Speaker 2: We are actually looking at the most perfectly preserved time
[36:37] Speaker 2: capsule of our own biological origins.
[36:39] Speaker 1: Wow.
[36:40] Speaker 2: It's definitely something to think about the next time you
[36:42] Speaker 2: look up at that little red dot in the night sky.
[36:45] Speaker 2: Have a wonderful rest of your day and keep looking up.

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