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 imagine, just for a second, that
Speaker 2: you are standing in a dry, freezing, just incredibly dusty
Speaker 2: crater on another planet.
Speaker 3: Yeah, an absolutely brutal environment.
Speaker 2: Exactly. The sky above you isn't blue. It's this hazy
Speaker 2: butterscotch color tinted by all that iron oxide dust just
Speaker 2: suspended in the thin air, right, And the atmosphere is
Speaker 2: so wispy, I mean, it's mostly carbon dioxide, less than
Speaker 2: one percent the density of Earth's You couldn't breathe it
Speaker 2: even if it magically filled with oxygen right then and there.
Speaker 3: No, you'd suffocate immediately and freeze.
Speaker 2: Yeah, freeze. Because the temperature is hovering somewhere around eighty
Speaker 2: degrees below zero. There is no sound but this thin wind.
Speaker 2: It is utterly barren, like a sterile desert, right, but
Speaker 2: then you kneel down, you brush away that rusty red
Speaker 2: top layer of dirt you screep just I don't know,
Speaker 2: a couple of inches into the rock beneath and staring
Speaker 2: back at you are the very chemical building blocks of DNA.
Speaker 3: I mean, it sounds like the opening scene of a
Speaker 3: science fiction novel right where the protagonist makes this impossible discovery.
Speaker 2: It really does.
Speaker 3: But we are looking at hard, peer reviewed reality today,
Speaker 3: and it's a reality that completely shatters our previous assumptions
Speaker 3: about the chemistry of our solar.
Speaker 2: System because the surf on is basically a death zone exactly.
Speaker 3: We already know the Martian surface is essentially a sterilization
Speaker 3: engine unshielded UV radiation, and these highly reactive chemicals in
Speaker 3: the soil called perchlorates, well, they usually tear organic bonds
Speaker 3: apart in a matter of months, let alone millennia, which.
Speaker 2: Makes this monumental. And that's our mission today to really
Speaker 2: explore this. We are talking about NASA's Curiosity Mars rover, right,
Speaker 2: this car sized nuclear powered laboratory that has managed to
Speaker 2: pull off something planetary scientists have dreamed of for decades.
Speaker 3: It's an incredible engineering feature.
Speaker 2: In a specific spot on the Martian surface. This rover
Speaker 2: has successfully uncovered a diverse mix of never before seen
Speaker 2: organic molecules and yes, that includes the literal precursors to DNA.
Speaker 3: Yeah.
Speaker 2: I mean, it is impossible to overstate how thrilling this is.
Speaker 2: We are looking at the potential seeds of life sitting
Speaker 2: right there in the dirt of our neighboring planet.
Speaker 3: It really is.
Speaker 2: It's the kind of discovery that forces you to look
Speaker 2: up at the night sky and just realize how incredibly
Speaker 2: dynamic our universe actually is.
Speaker 3: The thrill is absolutely justified. I agree, though, you know,
Speaker 3: I think we have to tamper that excitement just a
Speaker 3: bit by grounding ourselves in the sheer, staggering time scale
Speaker 3: of what we are analyzing.
Speaker 2: Here, right, the three point five billion years part.
Speaker 3: Exactly. The true marvel here isn't just the inventory of
Speaker 3: what the rover found, is the fact that these complex
Speaker 3: molecular structures survived at.
Speaker 2: All because Mars doesn't have a magnetic field like we do.
Speaker 3: Right. Mars is a giant, unshielded radiation chamber. It lacks
Speaker 3: a global magnetic field to deflect galactic cosmic rays and
Speaker 3: solar energetic particles. Just relentlessly bombard the surface. Wow, Ionizing
Speaker 3: radiation functions like a like a microscopic wrecking ball, systematically
Speaker 3: smashing into complex molecules and breaking their delicate carbon bonds
Speaker 3: over deep time.
Speaker 2: Just constantly chipping away at them.
Speaker 3: Yeah, exactly so. Finding intact macromolecules that endure this bootle
Speaker 3: environment for billions of years completely redefines our baseline understanding
Speaker 3: of planetary preservation models.
Speaker 2: Well, let me stop you there, because that immediately raises
Speaker 2: a massive question. Sure, if the surface is a sterilization
Speaker 2: engine and cosmic rays are acting like microscopic wrecking balls
Speaker 2: for three and a half billion years, how on Earth,
Speaker 2: or rather how on Mars did anything survive?
Speaker 3: Right? It seems impossible.
Speaker 2: It defies logic, which means we have to look at
Speaker 2: the exact spot where the rover parked. Right. Curiosity didn't just,
Speaker 2: you know, stumble upon these fragile molecules randomly while rolling
Speaker 2: across the dunes.
Speaker 3: No, not at all. Survival in that kind of environment
Speaker 3: is never random. If Curiosity had parked a few miles away,
Speaker 3: we wouldn't be having this conversation right now.
Speaker 2: Wait, really, just a few miles.
Speaker 3: Just a few miles the rover had to find a
Speaker 3: very specific geologic vault. Curiosity landed in Gale Crater back
Speaker 3: in August of twenty twelve. And Gale Crater is this
Speaker 3: massive impact basin formed billions of years ago.
Speaker 2: And it used to be a lake, right.
Speaker 3: Yes, we are fairly certain it hosted an ancient, long
Speaker 3: lived lake system. But the specific samples we were dissecting
Speaker 3: today weren't taken in twenty twelve.
Speaker 2: Well they weren't.
Speaker 3: No, they weren't taken in twenty fourteen or twenty sixteen either.
Speaker 3: The rover had to meticulously climb the foothills of the
Speaker 3: crater's central peak, Mount Sharp. It took it till twenty nineteen,
Speaker 3: when it finally drove into a highly specialized region called
Speaker 3: Glenn Torden.
Speaker 2: Okay, let's unpack this. Glenn Torden isn't just another patch
Speaker 2: of rusty terrain, is it not?
Speaker 3: At all? The rover specifically targeted a clay bearing unit
Speaker 3: within this region, which the science team nicknamed Mary anning Ah.
Speaker 2: After the nineteenth century English palaeontologists who discovered Jurassic marine
Speaker 2: fossil beds.
Speaker 3: Exactly, and calling it a clay bearing unit is the
Speaker 3: absolute crux of this entire story, because.
Speaker 2: Clay is special. I like to think of this specific
Speaker 2: Martian clay as like cosmic tupperware.
Speaker 3: Cosmic tupperware. I like that.
Speaker 2: Yeah, it's a geologic container ceiling in the chemical freshness
Speaker 2: of Mars from three and a half billion years ago,
Speaker 2: just completely locking out the destructive, irradiated environment of the surface.
Speaker 3: That analogy holds up surprisingly well under microscopic scrutiny. Actually, yeah,
Speaker 3: when we talk about clay implanetary science, we aren't just
Speaker 3: talking about you know, wet mud. We are talking about phylicilicates,
Speaker 3: smecktight clays, specifically.
Speaker 2: Smack tighte clays. Okay, what makes them so good at
Speaker 2: being tupperware?
Speaker 3: Well, on a molecular level, these clays are structured in
Speaker 3: incredibly tight microscopic layers, almost like the pages of a
Speaker 3: tightly bound book.
Speaker 2: Oh. Interesting.
Speaker 3: When liquid water flows through volcanic rock over long periods
Speaker 3: of time, it chemically alters the primary minerals like olivine
Speaker 3: and pyroxene into these layered silicates.
Speaker 2: Okay, So the water changes the.
Speaker 3: Rock, right, and when that alteration happens, organic chemicals flowing
Speaker 3: in that water can essentially get trapped right between these
Speaker 3: microscopic sheets.
Speaker 2: So the clay physically swallows the organics like it just
Speaker 2: traps them inside the pages of the book.
Speaker 3: It traps them, yes, but it also chemically binds them.
Speaker 3: The surfaces of these clay layers have slight electrical charges
Speaker 3: that hold onto organic molecules.
Speaker 2: Oh wow, so it's not just a physical box. It's
Speaker 2: grabbing onto them exactly.
Speaker 3: The clay minerals act as heavy duty protective vaults. They
Speaker 3: physically shield the trapped organics from the ionizing radiation raining
Speaker 3: down from space, and they protect them from the chemical
Speaker 3: oxide driven by the perchlorids on the surface.
Speaker 2: That makes total sense.
Speaker 3: If you want to find preserved organics on a dead world,
Speaker 3: you follow the clay. This actually circles directly back to
Speaker 3: Curiosity's original mission.
Speaker 2: Mandate, right, because people forget that goal wasn't to find
Speaker 2: little green men.
Speaker 3: No, when the rover launched in twenty eleven, its primary
Speaker 3: goal wasn't to find living microbes. The goal was to
Speaker 3: find evidence that ancient Mars had the specific environmental conditions
Speaker 3: that could have supported microbial life billions of years.
Speaker 2: Ago, right, the habitability factor. But I'm looking at this
Speaker 2: finding and my immediate thought is, Okay, we know Gale
Speaker 2: Crater was a massive lake. Yes, we know glenn Torden
Speaker 2: is full of clay formed by water interacting with rock.
Speaker 2: So water was clearly present for a massive stretch of
Speaker 2: time denied. But does water automatically equal a habitable environment?
Speaker 2: Because you know we have places on Earth like certain
Speaker 2: ultra acidic volcanic lakes or highly irradiated zones that have
Speaker 2: water but are completely devoid of life.
Speaker 3: You're hitting on the critical distinction that drives astrobiology. Water
Speaker 3: is the solvent necessary for life as we know it,
Speaker 3: but it is entirely insufficient on its own right.
Speaker 2: Just having a glass of water doesn't mean something can
Speaker 2: live in it exactly.
Speaker 3: To declare an environment truly habitable, you need a confluence
Speaker 3: of three major pillars.
Speaker 2: Okay, what are the three?
Speaker 3: First, you need that liquid water solvent. Second, you need
Speaker 3: an energy source to drive metabolism like sunlight sunlight for photosynthesis,
Speaker 3: sure or chemical gradients and geothermal heat for chemosynthesis like
Speaker 3: we see in deep ocean hydrothermal vents here on Earth.
Speaker 2: Okay, so water and energy, what's a third?
Speaker 3: And third? You need the elemental building blocks of life which,
Speaker 3: as scientists often abbreviate as hnopshnops.
Speaker 2: That's carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur.
Speaker 3: Right, you got it. The clay in Gale Crater proved
Speaker 3: the long standing water pillar, but to prove full habitability,
Speaker 3: Curiosity had to definitively find those complex Organicsware is useless
Speaker 3: to our search for life if we open it up
Speaker 3: and find it completely empty.
Speaker 2: Wow. Yeah, which brings us to an absolutely massive engineering nightmare. Oh,
Speaker 2: it was a nightmare, because finding the ultimate cosmic tupperware
Speaker 2: is a triumph in itself. We sent a robot tens
Speaker 2: of millions of miles, landed it via a sky crane,
Speaker 2: which is still insane to me, and drove it for
Speaker 2: seven years to find this specific mudstone.
Speaker 3: It's incredible.
Speaker 2: But figuring out how to pop the lid open right
Speaker 2: to crack into those microscopic clay vaults and read the
Speaker 2: chemical signatures inside that required one of the most high
Speaker 2: stakes limited resource experiments in the entire history of space exploration.
Speaker 3: The sheer audacity the engineering required to achieve this is
Speaker 3: just staggering. To pop that lid, The rover utilized an
Speaker 3: onboard instrument suite called SAM.
Speaker 2: SAM that stands for Sample Analysis of Mars.
Speaker 3: Right exactly, and this particular highly specialized experiment was led
Speaker 3: in part by astrobiologist Jennifer Eigenbrode at NASA's Goddard Space
Speaker 3: Flight Center. Okay, now SAM isn't just a single it's
Speaker 3: effectively a miniaturized analytical chemistry lab tucked right inside the
Speaker 3: belly of the rover.
Speaker 2: Like a full lab shrunked down.
Speaker 3: Yeah, it contains a gas chromatograph, a quadrupole mass s pectrometer,
Speaker 3: and a tunable laser spectrometer.
Speaker 2: That is a lot of fancy equipment in a small box,
Speaker 2: it is.
Speaker 3: But this specific dig at mary Anning wasn't a standard
Speaker 3: run of the mill SAM test. To coax these complex
Speaker 3: organics out of their clay vaults without destroying them in
Speaker 3: the process, the team had to use a highly specialized
Speaker 3: chemical region called TMAH.
Speaker 2: Okay TMAH tetra misleamonium hydroxide for the organic chemists listening
Speaker 2: who love a mouthful of syllables, that's the one.
Speaker 3: And to understand why TMAH is so crucial, you have
Speaker 3: to understand how SAM normally operates.
Speaker 2: Right, how does it normally check the dirt.
Speaker 3: Usually the rover's robotic arm drills into a rock, collects
Speaker 3: a powdered sample, and drops it into a tiny quartz
Speaker 3: cup inside SAM.
Speaker 2: Okay, it makes sense.
Speaker 3: The instrument then heats that dirt up to roughly eight
Speaker 3: hundred degrees celsius, process called pyrolysis.
Speaker 2: Eight hundred degrees.
Speaker 3: Yeah. As the dirt bakes, gases boil off, and the
Speaker 3: mass spectrometer basically sniffs those gases to see what they
Speaker 3: made of.
Speaker 2: Okay, I have to interject here because heating Martian dirt
Speaker 2: to eight hundred degrees seems like a massive design flaw
Speaker 2: if you are looking for fragile, three and a half
Speaker 2: billion year old organic molecules.
Speaker 3: It sounds counterintuitive. I know.
Speaker 2: If I take a complex organic structure, like I don't
Speaker 2: know a sugar or an amino acid, and I've glassed
Speaker 2: it with eight hundred degrees of heat, I don't get gas.
Speaker 2: I get a burnt, carbonized mess. I'm essentially making charcoal.
Speaker 3: Right. It's not a flaw, but it is the fundamental
Speaker 3: constraint of the technology available when SAM was designed in
Speaker 3: the early two thousands. Okay, and you are entirely correct
Speaker 3: about the chemistry. Large complex organic molecules, especially ones that
Speaker 3: have already been battered by cosmic radiation. They do not easily.
Speaker 2: Volatilize, meaning they don't turn into gas neatly exactly.
Speaker 3: They degrade, they fracture, They turn it into a morphous
Speaker 3: carbon or char. When Sam bakes them, normally, the mass
Speaker 3: spectrometer often just sees carbon dioxide, water vapor coming.
Speaker 2: Off, just the smoke.
Speaker 3: Basically yeah, yeah, the ghostly combusted remains of what used
Speaker 3: to be a complex organic molecule. The instrument knows something
Speaker 3: organic was there, but the original structure is completely lost
Speaker 3: to the fire.
Speaker 2: Which is exactly why they needed TMAH. So how does
Speaker 2: this chemical stop the organics from burning into useless ash?
Speaker 3: Well, TMAH performs a brilliant chemical trick called thermochemolysis.
Speaker 2: Okay, break that down for us.
Speaker 3: Thermo for heat, chemo for chemical, and lysis for breaking.
Speaker 3: When TMH is missed with the Martian dirt and heated,
Speaker 3: it doesn't just passively watch the molecules burn. It actively
Speaker 3: attacks them.
Speaker 2: Oh, it goes on the offensive.
Speaker 3: Yeah. TMAH is a strong base and it chemically fragments larger,
Speaker 3: stubborn organic macromolecules. Into smaller manageable pieces. But crucial to
Speaker 3: this process, it performs something called methylation. As it breaks
Speaker 3: the molecules part the TMAH donates methyl groups. That's one
Speaker 3: carbon atom attached to three hydrogen atoms and attaches them
Speaker 3: to the broken highly reactive ends of the organic.
Speaker 2: Fragments, so it caps them off so they don't burn.
Speaker 3: Precisely, it protects them, allowing them to volatilize into gas
Speaker 3: without turning into charcoal.
Speaker 2: That is genius. But here's the part that stresses me
Speaker 2: out just thinking about it. Imagine packing for a decade long,
Speaker 2: multi million mile road trip across a hostile desert. Right, sure,
Speaker 2: but you're only allowed to bring exactly two fluid ounces
Speaker 2: of engine coolant for the entire journey.
Speaker 3: That's a good way to put it.
Speaker 2: Because you have a car sized robot roaming an entire
Speaker 2: planet and it only had two tiny cups of this
Speaker 2: liquid tma H chemical on board, two cups, two cups
Speaker 2: for the entire multi year life span of the mission.
Speaker 2: It's like reaching the final most difficult puzzle of a
Speaker 2: vastly complex video game and realizing you only have a
Speaker 2: single lock pick to open the most important safe on Earth.
Speaker 2: And if you turn it too hard it snaps.
Speaker 3: Yeah, and the physical constraints of spaceflight force these kinds
Speaker 3: of impossible bottlenecks. When you're launching a payload to Mars,
Speaker 3: every single gram is negotiated.
Speaker 2: Everything costs fuel.
Speaker 3: Right, and liquids are exceptionally difficult to fly with. They
Speaker 3: require sealed, pressurized containment systems that have to survive the violent,
Speaker 3: bone rattling vibrations of launch, plus the cold, oh yeah,
Speaker 3: the freezing vacuum of interplanetary transit, and then the fiery
Speaker 3: deceleration of entering the Martian atmosphere. So yes, they only
Speaker 3: had two cups. And because of that terrifying scarcity, the
Speaker 3: patients required by the science team was just immense.
Speaker 2: I just can't imagine the tension you land in twenty twelve.
Speaker 2: You know, you have this incredibly powerful chemical lock pick
Speaker 2: in the rover's belly.
Speaker 3: You just have to wait.
Speaker 2: Yeah, How do planetary scientists handle the psychological pressure of
Speaker 2: knowing that one wrong scoop of dirt wastes a decade
Speaker 2: of waiting and searching a lot of pressure Because if
Speaker 2: they drill a rock mix in the TMAH and it
Speaker 2: turns out that specific rock was I don't know, too
Speaker 2: highly oxidized or lacked the right smectite clays, or had
Speaker 2: too much perchlorate. That's it.
Speaker 3: That's game over for the lock pick.
Speaker 2: You press enter on the code sending the command to Mars,
Speaker 2: and then you just sit in a control room on Earth,
Speaker 2: agonizing for the fourteen minute communication delay, waiting to see
Speaker 2: if you blew your one and only chance.
Speaker 3: They mitigate that pressure through a deeply exhausting, meticulous process
Speaker 3: of elimination. They didn't just.
Speaker 2: Guess, they couldn't afford to exactly.
Speaker 3: From twenty twelve to twenty nineteen, as Curiosity traversed from
Speaker 3: the Breadbury landing site through Yellowknife Bay and up the
Speaker 3: slopes of Mount Sharp, the team continuously analyzed the mineralogy
Speaker 3: of everything.
Speaker 2: They passed, using the other tools.
Speaker 3: Right, using the rovers, other instruments like chimin, which is
Speaker 3: the chemistry of mineralogy X ray diffraction instrument. They were
Speaker 3: constantly building a geological map, waiting for the absolute perfect,
Speaker 3: most favorable location.
Speaker 2: So they were passing up decent spots because they weren't perfect.
Speaker 3: Oh, they pass up dozens of interesting sites. They're doing
Speaker 3: sure the sample wasn't to acidic that the clay was
Speaker 3: authogenic ophogenic.
Speaker 2: What does that mean?
Speaker 3: It means it formed in place in the lake, rather
Speaker 3: than just being blown in by the wind from somewhere else.
Speaker 3: Oh okay, And they got to make sure that the
Speaker 3: radiation exposure was as low as possible. What's fascinating here
Speaker 3: is that the legacy of the SAM instrument is really
Speaker 3: built on this kind of disciplined precision.
Speaker 2: They really knew what they were doing.
Speaker 3: Yeah. Even before this specific TMH experiment, SAM had already
Speaker 3: revolutionized our understanding of Mars, quantifying the planet's atmospheric loss
Speaker 3: and detecting the seasonal spikes of background methane.
Speaker 2: But this was the main event. Mixing liquids with pulverized
Speaker 2: extraterrestrial rock, heating it precisely to trigger methylation without causing combustion,
Speaker 2: and analyzing the vaders at a molecular level, all happening
Speaker 2: autonomously inside a robot millions of miles away. It's a
Speaker 2: symphony of engineering, and the craziest part, it worked, It
Speaker 2: actually worked. The team took their shot. In twenty twenty,
Speaker 2: they finally authorized the use of their precious TMAH on
Speaker 2: the dirt pulled from the Marianning site in Glenn Torridon.
Speaker 2: They baked it, the TMAH chemically capped the fragments, and
Speaker 2: the mass spectrometer readouts that beamed back to Earth exceeded
Speaker 2: their wildest expectations.
Speaker 3: It was a watershed moment for astrobiology. The data analysis
Speaker 3: of this specific experiment was led by Amy Williams, a
Speaker 3: professor of geological sciences at the University of Florida, and
Speaker 3: her team published the findings in Nature Communications, and they
Speaker 3: found a lot. They didn't just find a faint whisper
Speaker 3: of carbon. The TMAH test revealed over twenty distinct complex
Speaker 3: organic chemical compound.
Speaker 2: Why ded That is a massive chemical hall huge.
Speaker 3: But among those twenty, there are two specific structural findings
Speaker 3: that genuinely altered the landscape of planetary science.
Speaker 2: Okay, let's hear them.
Speaker 3: First, they identified a nitrogen bearing molecule with a structure
Speaker 3: fundamentally similar to the nucleobases that formed the precursors of
Speaker 3: DNA wow. And second, they found a significant presence of benzothiophine,
Speaker 3: which is a large, double ringed sulfur based chemical.
Speaker 2: Okay, So if you were to look at the mass
Speaker 2: spectrometer readouts right now. You wouldn't see the letters DNA
Speaker 2: flashing on a screen.
Speaker 3: No, definitely not.
Speaker 2: You'd see a spike in mass to charge ratios, indicating
Speaker 2: a very specific heavy nitrogen bearing ring. You have to
Speaker 2: basically play detective to reconstruct what that ring used to
Speaker 2: be before three and a half billion years of radiation
Speaker 2: got to it.
Speaker 3: Right, you're looking at the fragments.
Speaker 2: But the conclusion is that we are looking at a
Speaker 2: DNA precursor, the literal structural foundation of genetic information as
Speaker 2: we understand it, just sitting there, frozen in a Martian
Speaker 2: lake bed exactly. And here's where it gets really interesting.
Speaker 2: And I have to push back on the scientific communities
Speaker 2: messaging here.
Speaker 3: Okay, lay it on me.
Speaker 2: We found the building blocks of DNA on Mars. Why
Speaker 2: isn't this front page above the fold news everywhere declaring
Speaker 2: we found aliens. It feels like scientists are deliberately downplaying this,
Speaker 2: framing it merely as chemistry rather than definitively by alogy.
Speaker 3: It is the most natural reaction to have, believe me,
Speaker 3: and it gets to the very heart of the rigor
Speaker 3: required by the scientific.
Speaker 2: Method, because it's not proof yet, right.
Speaker 3: The boundary between a biological building block, and actual functioning
Speaker 3: biological activity is a vast complicated gulf. How so, well,
Speaker 3: think of finding a nuclear base a DNA precursor like
Speaker 3: finding a single perfectly formed clay brick. A brick is
Speaker 3: incredibly useful. It is the fundamental unit you need if
Speaker 3: you want to build a complex house. But finding a
Speaker 3: single brick lying in an empty field does not prove
Speaker 3: that a house was ever actually built there, let alone
Speaker 3: that someone lived in it.
Speaker 2: Oh, that makes a lot of sense.
Speaker 3: Biology is not just a collection of chemicals. It's a
Speaker 3: highly organized, selective, energy consuming system. And the universe, it
Speaker 3: turns out, is remarkably good at forging the basic chemical
Speaker 3: bricks of life entirely on its own.
Speaker 2: Without life being involved at all, exactly.
Speaker 3: Through completely abiotic, non living physics and chemistry.
Speaker 2: Which ties perfectly into the second major chemical they found, benzothiophine. Yes,
Speaker 2: it does, because if I hear sulfur based organic ring,
Speaker 2: I immediately think of the sky, not the ground. Benzothiophine
Speaker 2: is heavily associated with meteorite delivery. Right, we know the
Speaker 2: universe is literally raining these complex carbon building blocks down
Speaker 2: on planets all the time.
Speaker 3: That is the crucial context. Benzothiophine is a fascinating molecule.
Speaker 3: It consists of a benzene ring fused to a thiophine
Speaker 3: ring incorporating a sulfur atom.
Speaker 2: And why is the sulfur important?
Speaker 3: Sulfur is incredibly important because it undergoes a process similar
Speaker 3: to vulcanization and rubber.
Speaker 2: Oh like toughening it up exactly.
Speaker 3: It cross links with organic molecules, making them incredibly tough
Speaker 3: and resistant to degradation.
Speaker 2: Okay, so they survive the trip through space.
Speaker 3: Right, But more importantly, as you noted, these exact types
Speaker 3: of molecules are routinely found inside carbonaceous chondrite meteorites. Amy
Speaker 3: Williams made a profound observation about this dynamic.
Speaker 2: What did she say?
Speaker 3: Well, she noted that the early Solar System around three
Speaker 3: point eight to four or billion years ago, during the
Speaker 3: Late Heavy bombardment, was a chaotic, violent place. The exact
Speaker 3: same meteoric material that rained down on Mars is what
Speaker 3: rained down on Earth. Really, Yeah, the inner Solar System
Speaker 3: was bathed in the exact same organic inventory.
Speaker 2: So Earth wasn't special in its ingredients.
Speaker 3: Not at all. Both worlds received the exact same cosmic
Speaker 3: grocery delivery. On Earth, those complex molecular building blocks were
Speaker 3: eventually caught up in a cycle of hydrothermal energy and
Speaker 3: liquid water and were utilized by emerging biological systems.
Speaker 2: And on Mars.
Speaker 3: On Mars, they might have just fallen into the quiet
Speaker 3: waters of Gale Crater, sunk to the bottom, gotten trapped
Speaker 3: in the microscopic layers of coming smectite clay, and just
Speaker 3: sat there in perfect cold preservation for billions of years.
Speaker 2: Wow. Which means my earlier frustration about scientists not declaring
Speaker 2: we found life is exactly what the entire scientific community
Speaker 2: is wrestling with right now.
Speaker 3: Yeah, it's the big debate.
Speaker 2: Because of the Samtmah experiment, we finally know, without a
Speaker 2: shadow of a doubt, what is in the Martian dirt.
Speaker 2: The tupperware is full, yes it is. But the hardest
Speaker 2: puzzle in the Solar system is figuring out the causal
Speaker 2: mechanism of how it got there.
Speaker 3: That is the absolute crux of the origin ambiguity, and
Speaker 3: it highlights the inherent limitations of even our most advanced
Speaker 3: robotic experiments.
Speaker 2: Right because the rover can only tell us so much.
Speaker 3: Exactly the tmah wet chemistry test on curiosity is a
Speaker 3: triumph of remote engineering, but it cannot definitively distinguish the
Speaker 3: origin story of these chemical compounds.
Speaker 2: So we have options we do.
Speaker 3: When we look at that benzothiophine or that nitrogen bearing
Speaker 3: DNA precursor, we are faced with three equally plausible hypotheses.
Speaker 2: We go through them.
Speaker 3: First, the biological hypothesis. These organics are the degraded, fragmented
Speaker 3: remnants of the metabolic processes of actual ancient Martian microbes
Speaker 3: that lived in Gale crater.
Speaker 2: The alien life option. Okay, what's next.
Speaker 3: Second, the abiotic geological hypothesis. These compounds were formed entirely
Speaker 3: through non living processes like what kind of processes such
Speaker 3: as fischer Trops type reactions in hydrothermal vents deep underground
Speaker 3: where hot water interacts with carbon dioxide and hydrogen to
Speaker 3: synthesize complex hydrocarbons.
Speaker 2: Okay, so the planet just bake them up itself, right?
Speaker 2: And the third is the exogenous hypothesis, the meteorite delivery
Speaker 2: system exactly, you know, I look at this chemical ambiguity
Speaker 2: like walking into a kitchen and finding a bag of flour.
Speaker 2: Some sugar and a carton of eggs sitting on the counter.
Speaker 3: Okay, I like this.
Speaker 2: It could mean someone was actively in there baking a cake,
Speaker 2: whipping up a complex recipe, which represents biological life. Or
Speaker 2: it could just mean someone dropped off raw groceries and
Speaker 2: bags and left the house, which represents meteorites delivering the
Speaker 2: chemicals from space.
Speaker 3: That is a perfect analogy, right.
Speaker 2: The ingredients sitting on the counter are exactly the same
Speaker 2: in both scenarios, but the story of how they got
Speaker 2: there completely changes our understanding of the universe completely. So
Speaker 2: what does this all mean? How do we solve this?
Speaker 2: If a bill VN dollar car sized chemistry lab on
Speaker 2: wheels can't tell the difference between raw groceries and a
Speaker 2: baked cake, what are we supposed to do.
Speaker 3: To solve that? We have to look for signatures that
Speaker 3: are uniquely undeniably biological. We have to look for things
Speaker 3: like isotopic fractionation or HOMLK chorality.
Speaker 2: Okay, hold on, let's break those down, because that is
Speaker 2: where the real detective work happens.
Speaker 3: Sure, let's take isotopic fractionation. Okay, life is fundamentally lazy.
Speaker 3: It always takes the path of least resistance, don't we
Speaker 3: all right? Carbon exists in different isotopes, primarily carbon twelve,
Speaker 3: which is lighter, and carbon thirteen, which has an extra
Speaker 3: neutron and is heavier.
Speaker 2: Okay, so twelve is lighter, thirteen is heavier.
Speaker 3: Because carbon twelve is lighter, it requires slightly less energy
Speaker 3: to incorporate into metabolic processes. So biological systems preferentially consume
Speaker 3: carbon twelve.
Speaker 2: Oh, because it's easier to lift.
Speaker 3: Basically exactly, if you find a depositive organic matter and
Speaker 3: it has a heavily skewed ratio favoring carbon twelve far
Speaker 3: beyond the standard geological background levels, yeah, well that is
Speaker 3: a massive flashing neon sign pointing toward biology.
Speaker 2: So life leaves a chemical preference. And what was the
Speaker 2: second one? Chirality.
Speaker 3: Chirality is basically handedness. Many complex organic molecules, like amino
Speaker 3: acids can form in two mirror image.
Speaker 2: Structures like literal hands.
Speaker 3: Right, think of your left and right hands. They have
Speaker 3: the same components, but you can't perfectly superimpose them.
Speaker 2: Okay, so molecules do that too.
Speaker 3: They do when organics form in space on a meteorite.
Speaker 3: Abiotic chemistry produces a roughly fifty to fifty split of
Speaker 3: left handed and right handed molecules, an even mix, yeah,
Speaker 3: what we call a racemic mixture. But life on Earth
Speaker 3: is incredibly specific. Every biological system on this planet exclusively
Speaker 3: uses left handed amino acids and right handed sugars. Wait
Speaker 3: all of them, all of them. It's called homol chorality.
Speaker 3: If we find a batch of organics on Mars and
Speaker 3: they are entirely left handed, that essentially eliminates the media
Speaker 3: write hypothesis.
Speaker 2: Because metiaorrites would be fifty to fifty exactly. But the
Speaker 2: SAM instrument, even with the TMAH lock pick, can't reliably
Speaker 2: measure that kind of microscopic, isotopic and structural detail, especially
Speaker 2: on organics that have been degraded by billions of years
Speaker 2: of radiation.
Speaker 3: No, it can't. Curiosity proved the building blocks are there
Speaker 3: and that the Gale crater environment was highly habitable. It
Speaker 3: found the tupperware, and it found the ingredients inside, right,
Speaker 3: But to definitively tell if those ingredients were organized into
Speaker 3: a living system. To check for homokality and isotopic biosignatures,
Speaker 3: we absolutely must look at the microscopic structure of the
Speaker 3: rocks in a pristine laboratory setting on Earth.
Speaker 2: We need our big tools we do.
Speaker 3: We need equipment the size of entire buildings using synchotron
Speaker 3: particle accelerators and electron microscopes, rather than an instrument the
Speaker 3: size of a microwave tucked.
Speaker 2: Inside a rover, which explains the entire strategic progression of
Speaker 2: NASA's Mars exploration program over the last decade.
Speaker 3: If we connect this to the bigger yes, absolutely.
Speaker 2: It's not just a series of random rover drops, It's
Speaker 2: an escalating chain of scientific relay races. Curiosity was the scout, Yes,
Speaker 2: the scout. Its job was to find the habitable conditions
Speaker 2: and prove the organics survived. Once Curiosity found that nitrogen
Speaker 2: bearing ring and the benzotheophanes in twenty twenty, it gave
Speaker 2: the green light to the next generation. That is exactly
Speaker 2: why the Perseverance rover, which landed in Jazzero Crater in
Speaker 2: twenty twenty one, has a completely different job description.
Speaker 3: Precisely, or rather, that's exactly the evolution of the mission architecture.
Speaker 3: Perseverance is not just looking for habitability. It is explicitly
Speaker 3: tasked with seeking definitive signs of ancient microbial.
Speaker 2: Life, right, it's looking for the fossils exactly.
Speaker 3: And instead of just analyzing the dirt onboard and leaving
Speaker 3: it behind like Curiosity does, Perseverance is actively drilling pristine
Speaker 3: rock cores to bring them back. Well, it's sealing them
Speaker 3: in ultra clean titanium tubes and cashing them on the
Speaker 3: Martian surface, just.
Speaker 2: Leaving them there for pickup exactly. And all of that
Speaker 2: hinge is entirely on the future Mars sample return architecture,
Speaker 2: which is arguably the most complex robotic space mission ever conceived.
Speaker 3: Oh, without a doubt.
Speaker 2: I mean, we have to send an Earth return orbiter
Speaker 2: to Mars, drop a sample retrieval lander to the surface,
Speaker 2: have a small thatcherrover or helicopters pick up those titanium
Speaker 2: tubes from Perseverance, load them into a Mars ascent vehicle,
Speaker 2: which is a rocket launching off the surface of another
Speaker 2: planet by the.
Speaker 3: Way, for the first time ever.
Speaker 2: Yeah, then rendezvous with the orbiter in space and flight them.
Speaker 3: All the way back to Earth. It is a staggering
Speaker 3: logistical chain, yeah, and it will take years, likely stretching
Speaker 3: into the next decade before those physical samples make the
Speaker 3: multimillion mile trip back to terrestrial laboratories.
Speaker 2: So we still have a long wait.
Speaker 3: We do, but while we wait for that ultimate physical evidence,
Speaker 3: the success of the TMAH chemical lock pick experiment on
Speaker 3: Curiosity hasn't just become a footnote in history. It has
Speaker 3: quite literally rewritten the playbook for how humanity designs the
Speaker 3: chemical exploration of the rest of the Solar System.
Speaker 2: Because we prove the concept, we know definitively that you
Speaker 2: can take a highly volatile chemical region like TMAH, shoot
Speaker 2: it into space, keep it stable for eight years, mix
Speaker 2: it with alien dirt remotely, and successfully extract heavily degraded
Speaker 2: billion year old organic macromolecules without destroying them exactly.
Speaker 3: And because that methodology is now prooven, it is being exported.
Speaker 3: It is no longer just a Martian tool.
Speaker 2: Where else is it going well?
Speaker 3: The European Space Agency is incorporating this exact type of
Speaker 3: wet chemistry testing into the Roslin Franklin mission to Mars
Speaker 3: oh Nice and significantly, the Roslin Franklin rover is designed
Speaker 3: with a drill capable of penetrating two meters deep into
Speaker 3: the Martian subsurface.
Speaker 2: Two meters Curiosity only scraped a couple of inches down.
Speaker 3: Right, By going two meters deep, Roslin Franklin will be
Speaker 3: sampling organics that have been completely shielded from the ionizing
Speaker 3: radiation that destroyed the top layers.
Speaker 2: So we're finally getting below the wrecking balls.
Speaker 3: We are.
Speaker 2: But what truly blows my mind is that this technology
Speaker 2: is leaving Mars entirely. This exact chemical test is going
Speaker 2: to be incorporated into the Dragonfly expedition to Saturn's moon Titan.
Speaker 3: This raises an important question, right, because Titan is so different?
Speaker 2: Yeah, wait, we're taking Mars tactics to Saturn's moons now
Speaker 2: we are. Now, Titan isn't a dusty, irradiated red desert.
Speaker 2: It's a completely different paradigm. It is an ice world
Speaker 2: sitting in the deep frieze of the outer Solar System,
Speaker 2: very deep freeze, enveloped in a thick, smoggy atmosphere where
Speaker 2: liquid methane and ethane rain from the sky, carving actual
Speaker 2: river valleys and forming vast hydrocarbon lakes. How does a
Speaker 2: chemical test designed to crack open dry Martian smectite clay
Speaker 2: translate to an ice moon billions of miles further away?
Speaker 3: The environment changes short but the fundamental chemical problem remains identical.
Speaker 3: Really how so well Titan's surface and atmosphere operate essentially
Speaker 3: as a planet scale organic chemistry factory. Photochemical reactions in
Speaker 3: its upper atmosphere constantly break apart methane and nitrogen, creating
Speaker 3: what creating complex heavy organic molecules called tholins that slowly
Speaker 3: drift down to the icy surface like a steady snowfall.
Speaker 2: Like an organic snow that is wild it is.
Speaker 3: The Dragonfly mission is a nuclear powered eight rotor drone
Speaker 3: that will literally fly from location to location across titans
Speaker 3: dunes and craters, sampling this organic snow.
Speaker 2: A nuclear drone flying through methane skies, it still doesn't
Speaker 2: feel real.
Speaker 3: It's incredible engineering. But the scientists designing Dragonfly face the
Speaker 3: exact same problem Jennifer Eigenbrode and Amy Williams faced with
Speaker 3: Sam on Mars, the burning problem exactly. Titan's surface is
Speaker 3: incredibly cold, around ninety four kelvin or minus two hundred
Speaker 3: and ninety degrees fahrenheit. The heavy organics covering the surface
Speaker 3: are frozen solid and highly complex. Okay, if the Dragonfly
Speaker 3: drone lands scoops up that icy, organic rich material, and
Speaker 3: just blasts it with a heater to vaporize it for
Speaker 3: a mass spectrum.
Speaker 2: They turned to charcoal.
Speaker 3: Right, those massive, complex tholen molecules will fracture, to grade
Speaker 3: and burn just like they would have on Mars. You
Speaker 3: will lose all that structural information. They need a way
Speaker 3: to gently volatilize the heaviest, most complex molecules on the Moon.
Speaker 2: So they are bringing the lock pick to Saturn.
Speaker 3: They are.
Speaker 2: They will use thermochomolysis, breaking the molecules apart chemically and
Speaker 2: capping them with methyl groups so they float up as
Speaker 2: readable gases even in the freezing methane environment of Titan.
Speaker 3: Yes, the two cup gamble on curiosity didn't just solve
Speaker 3: a local mystery in Gale Crater. It proved that complex
Speaker 3: wet chemistry can be automated and executed flawlessly in brutal
Speaker 3: alien conditions.
Speaker 2: It opened the door.
Speaker 3: By testing and validating this concept in the dry, dusty
Speaker 3: clay of Mars, we gained a standard, highly reliable weapon
Speaker 3: in humanity's analytical arsenal. Whenever we go hunting for the
Speaker 3: molecular building blocks of life anywhere in the cosmos, whether
Speaker 3: it's the subsurface oceans of Europa or the methane lakes
Speaker 3: of Titan. We now know exactly how to open the
Speaker 3: vault without burning the treasure inside.
Speaker 2: It really is staggering to pull all these threads together.
Speaker 3: With a lot of information I know.
Speaker 2: We started this conversation standing in the freezing butterscotch tinted
Speaker 2: dust of Gale Crater. We walked through the deep geological history,
Speaker 2: exploring how the ancient flowing waters of Mars reacted with
Speaker 2: volcanic rock to form microscopic layered clay tupperware. We saw
Speaker 2: how those smectite clay layers physically and chemically locked away
Speaker 2: the organic secrets of a violently chaotic early solar system,
Speaker 2: shielding them from three and a half billion years of cosmic.
Speaker 3: Radiation, protected them perfectly.
Speaker 2: We looked at the agonizing eight year weight scientists endured
Speaker 2: just to use two tiny cups of a chemical lock pick,
Speaker 2: terrified of wasting their only shot, and we saw how
Speaker 2: that tension exploded into the discovery of massive, complex molecules
Speaker 2: from meteorite delivered benzothiophines to the literal nitrogen bearing precursors
Speaker 2: of DNA.
Speaker 3: Beautiful scientific arc.
Speaker 2: It is we prove that our neighboring barren planet was
Speaker 2: stocked with the exact same biological grocery list that eventually
Speaker 2: sparked life here on Earth.
Speaker 3: And I think it's deeply important for you listening to
Speaker 3: this right now to internalize your own physical connection to
Speaker 3: this science.
Speaker 2: I couldn't agree more.
Speaker 3: It is very easy to look at planetary exploration as
Speaker 3: something abstract, an expensive exercise in robotics happening hundreds of
Speaker 3: millions of miles away. But it is profoundly personal.
Speaker 2: It's about us exactly.
Speaker 3: The carbon atoms currently forming the cell walls in your body,
Speaker 3: the nitrogen atoms binding together the very rungs of your
Speaker 3: own DNA. As you listen to this, they share a
Speaker 3: direct cosmic history with the degraded molecules currently resting in
Speaker 3: the Glenord and dirt. Wow, the organic rain that blanketed
Speaker 3: the violent early Solar System fell indiscriminately. It fell on you,
Speaker 3: and it fell on Mars. When we use tools like
Speaker 3: SAM and TMAH to dissect the dirt of another world,
Speaker 3: we are quite literally studying our own chemical origins and
Speaker 3: a planet here.
Speaker 2: That is a hauntingly beautiful perspective, And it leaves me
Speaker 2: with one final thought for you to ponder. We know
Speaker 2: the ingredients are universal, We know the exact same organic
Speaker 2: groceries rained down on both Earth and Mars from meteorites
Speaker 2: three point eight billion years ago, and we now know definitively,
Speaker 2: thanks to a car sized rubber and a chemical called TMAH,
Speaker 2: that mars ancient clay was perfectly capable of catching those ingredients,
Speaker 2: holding them in a watery, highly habitable environment, and preserving
Speaker 2: them for eons. The table was perfectly set, it really was.
Speaker 3: So.
Speaker 2: Perhaps the most profound mystery moving forward isn't whether Mars
Speaker 2: could have supported life. Perhaps the real mystery, the one
Speaker 2: that should keep us awake at night, is what tiny microscopic,
Speaker 2: thermodynamic fork in the road caused Earth to wake up
Speaker 2: and start baking the cake, while Mars, with all the
Speaker 2: exact same ingredients, remained perfectly chemically asleep,