Mars's Hidden Heart: Unveiling the Red Planet's Solid Core

<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
<v Speaker 1>with our soothing Bedtime Astronomie podcast. Each episode offers a
<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for
<v Speaker 1>unwinding after a long day. Let's travel through the mysteries
<v Speaker 1>of the universe as you drift off into a peaceful
<v Speaker 1>slumber under the night sky.
<v Speaker 2>Welcome curious minds. Today, we're looking at something pretty radical,
<v Speaker 2>overturning a decade's old idea about Mars. Forget the notion
<v Speaker 2>of just a you know, a fully liquid, maybe dying
<v Speaker 2>heart beneath that dusty red surface. New seismic data this
<v Speaker 2>is from NASA's Insight mission. It reveals Mars holds a
<v Speaker 2>secret a solid core, and it's shockingly similar to Earth's,
<v Speaker 2>which is well, it's a discovery that completely rewrites the history,
<v Speaker 2>the really violent history of the red planet and its
<v Speaker 2>lost oceans.
<v Speaker 3>Yeah. What's truly remarkable here is how our understanding of
<v Speaker 3>Mars just keep evolving. It's constantly pushing the boundaries of
<v Speaker 3>what we thought was possible. You know, it forces us
<v Speaker 3>to reevaluate these long held assumptions we've had. We know,
<v Speaker 3>Mars today is well a cold, dry, seemingly desolate world,
<v Speaker 3>like a frozen desert basically, Yet the evidence that's been
<v Speaker 3>building up it strongly suggests a very different past, one
<v Speaker 3>that held this compelling promise of well abundant liquid water
<v Speaker 3>and perhaps you know, maybe even the potential for life right,
<v Speaker 3>and the key to unlocking this huge mystery, it turns out,
<v Speaker 3>lies hundreds of kilometers down way beneath its now dusty,
<v Speaker 3>arid surface.
<v Speaker 2>Yeah, for years, Mars has felt like this colossal planet
<v Speaker 2>sized cold case, hasn't it? How did it go from
<v Speaker 2>being potentially watery, maybe even vibrant, to the parched desert
<v Speaker 2>it is today. It's a question that's really driven decades
<v Speaker 2>of exploration absolutely and today are let's call them our
<v Speaker 2>forensic team, the scientists working with the Insight Mission. They
<v Speaker 2>finally cracked a really crucial piece of that puzzle. It's
<v Speaker 2>dramatically reshaping our understanding of Mars interior. We're talking incredible
<v Speaker 2>new insights from seismic studies. They literally offer us a
<v Speaker 2>peak into its innermost secrets, like a planetary autopsy report.
<v Speaker 3>Almost, And this raises a really important question for all
<v Speaker 3>of us. I think, what can the very core of
<v Speaker 3>a planet actually tell us about its entire history, it's trajectory,
<v Speaker 3>it's ultimate fate. We'll be looking at how these recent
<v Speaker 3>observations have not just refined, but really significantly deepened our models,
<v Speaker 3>suggesting that Mars might be far more like Earth deep
<v Speaker 3>down than we previously believed. And this is more than
<v Speaker 3>just geology, you know, it's a profound story planetary evolution,
<v Speaker 3>the delicate balance of magnetic fields, and the incredibly specific
<v Speaker 3>conditions that are required for a world to remain hospitable,
<v Speaker 3>to hold on to its life giving potential over well
<v Speaker 3>cosmic time scales.
<v Speaker 2>So our mission today as we dive into this is
<v Speaker 2>really to uncover the secrets of Mars's core, understand why
<v Speaker 2>it's structure and its history matters so much to the
<v Speaker 2>planet's past and maybe its future, and so to see
<v Speaker 2>how science, like a you know, a persistent detective, painstakingly
<v Speaker 2>builds knowledge step by careful steps. So, yeah, prepare to
<v Speaker 2>have your assumptions about the Red planet challenged.
<v Speaker 3>Well. Trace this fascinating journey of scientific discovery right from
<v Speaker 3>the initial hypotheses, which were often based on remote observations,
<v Speaker 3>you know, looking from orbit to the latest and most
<v Speaker 3>precise seismic measurements from insight. And we'll try to connect
<v Speaker 3>these seemingly abstract, kind of complex details to the grand
<v Speaker 3>sweeping narrative of Mars's really dramatic transformation. It really is
<v Speaker 3>a planetary detective story.
<v Speaker 2>Okay, So let's start with the Mars. We think we know,
<v Speaker 2>the one we see today when we look up at
<v Speaker 2>the night sky see that unmistakable red dot, or when
<v Speaker 2>we see those amazing images beamed back by the rovers,
<v Speaker 2>what comes to mind? I mean, it's a vast chili desert, right,
<v Speaker 2>that's the image most of us have precisely.
<v Speaker 3>Yeah, you've captured it perfectly. The Mars we observe today
<v Speaker 3>is characterized by an extremely thin atmosphere, really thin. It's
<v Speaker 3>mostly carbon dioxide, something like ninety five percent. And this
<v Speaker 3>thin on belowe it offers very little protection from solar radiation.
<v Speaker 3>The surface pressure is less than one percent of Earth's
<v Speaker 3>at sea level, just.
<v Speaker 2>Incredibly wow, less than one percent.
<v Speaker 3>Yeah, And temperatures well, they rarely if ever get above freezing,
<v Speaker 3>often plunging way down to minus sixty degrees celsius or
<v Speaker 3>even colder at the poles. And the almost complete lack
<v Speaker 3>of significant stable liquid water on the surface. That's one
<v Speaker 3>of its most defining features right now. It is, by
<v Speaker 3>all accounts, a very harsh place inhospitable, a true frozen desert.
<v Speaker 2>And you think about those pictures, those iconic images from
<v Speaker 2>the rovers, spirit, opportunity, curiosity, perseverance. You see those dusty,
<v Speaker 2>rust colored planes stretching out forever, barren, rocky landscapes, those clear,
<v Speaker 2>often kind of salmon pink skies, sometimes with those swirling
<v Speaker 2>dust devils. It's got this men's geological beauty for sure.
<v Speaker 2>That absolutely not a place you'd picture taking a swim
<v Speaker 2>right or finding a river, seeing oceans. It feels like
<v Speaker 2>a world strip bear of the very things that make
<v Speaker 2>Earth so well alive. But that's not the complete picture,
<v Speaker 2>is it not? By a long shot. That stark reality
<v Speaker 2>of Mars today actually makes the evidence for past water
<v Speaker 2>even more compelling, doesn't it. It really underlines the sheer scale
<v Speaker 2>of the change the planet went through. There's a huge
<v Speaker 2>amount of compelling, really undeniable evidence telling a very different
<v Speaker 2>story about Mars's past, a time when it was a
<v Speaker 2>very different kind of world.
<v Speaker 3>Indeed, Yeah, what's truly remarkable is the overwhelming geological evidence
<v Speaker 3>meticulously gathered over decades by orbiters and rovers like Curiosity
<v Speaker 3>and Perseverance. This evidence suggests that liquid water once flowed freely, abundantly,
<v Speaker 3>even and perhaps for long periods across the Martian surface.
<v Speaker 3>We're talking about conditions that were well, incredibly far more
<v Speaker 3>hospitable than anything we see today, a Mars that would
<v Speaker 3>be honestly unrecognizable to us, maybe resembling a young.
<v Speaker 2>Earth, a young or wow. So what kind of evidence
<v Speaker 2>are we talking about specifically?
<v Speaker 3>Well, comes in many forms, and each one is like
<v Speaker 3>a powerful clue, really undeniable. For instance, we found numerous
<v Speaker 3>dry lake beds. These are expansive basins that clearly once
<v Speaker 3>held standing water, and you see ancient shorelines, delta structures,
<v Speaker 3>sedimentary fans like river deltas exactly. I consider Jeseral Crater
<v Speaker 3>where perseverances right now. The images show these intricate river
<v Speaker 3>deltas very much like say the Mississippi delta here on Earth.
<v Speaker 3>This is where river once flowed into a vast lake,
<v Speaker 3>depositing sediments over potentially millions of years. And within those
<v Speaker 3>ancient sediments, scientists have found specific minerals, things like clays
<v Speaker 3>and sulfates, phyllosilicates like smectite chlorite, or evaporates like gypsum jerriscite.
<v Speaker 3>These are minerals that could only have formed if liquid
<v Speaker 3>water was present for a long time. They're not subtle hints,
<v Speaker 3>they're definitive chemical signatures, like a chemical fingerprint of past
<v Speaker 3>water locked away for billions of years.
<v Speaker 2>Okay, so dry lakes, specific minerals.
<v Speaker 3>What else, Well, beyond that, we see these dramatic valley
<v Speaker 3>networks etched into the landscape. They're not just random cracks,
<v Speaker 3>intricate branching systems, really similar in their shape their morphology
<v Speaker 3>to river systems on Earth. Think of those dendritic patterns
<v Speaker 3>you see in aerial photos of the Amazon Basin, for example,
<v Speaker 3>right like tree branches spreading out precisely. And these aren't
<v Speaker 3>just small channels. They're often kilometers wide, hundreds of meters deep.
<v Speaker 3>They're unmistakable evidence carved by the relentless flow of ancient rivers,
<v Speaker 3>long lived rivers, not just you know, flash floods. And
<v Speaker 3>then there are the sedimentary layers. You can see them
<v Speaker 3>in canyon walls like in valasmarneras or exposed in crater rims.
<v Speaker 3>These finely stratified deposits laid down layer upon layer over
<v Speaker 3>vast time scales. There are textbook examples of deposition and
<v Speaker 3>standing bodies of water to light sediments settle in lakes
<v Speaker 3>or seas here on Earth, it indicates a long sustained
<v Speaker 3>period of water activity. All of this taken together piints
<v Speaker 3>this vivid, irrefutable picture of a world that was once
<v Speaker 3>rich in water.
<v Speaker 2>So yeah, this overwhelming evidence that really begs the question,
<v Speaker 2>doesn't it. How could a planet now so incredibly arid,
<v Speaker 2>so seemingly lifeless, have once supported such an abundance of
<v Speaker 2>liquid water. What allowed for that much thicker atmosphere and
<v Speaker 2>a milder climate, the conditions that were clearly needed for
<v Speaker 2>surface water to exist. It's just such a radical transformation,
<v Speaker 2>a monumental shift. What drove such a huge change?
<v Speaker 4>Okay, To really get a handle on Mars's incredible transformation
<v Speaker 4>from potentially watery to the col dry world we see,
<v Speaker 4>we need to understand something absolutely vital about our own planet. First, Earth,
<v Speaker 4>It's internal engine, it's heart, you could say. So, if
<v Speaker 4>we're trying to figure out Mars's big shift, we really
<v Speaker 4>need to start with Earth, don't we. I mean, why
<v Speaker 4>is our internal engine, so incredibly good at protecting our
<v Speaker 4>atmosphere and keeping life going.
<v Speaker 3>Yeah, well it connect this to the bigger picture, the
<v Speaker 3>whole idea of planetary habitability. A key property of Earth's
<v Speaker 3>remarkable ability to sustain life comes directly from its core.
<v Speaker 3>Our planet has what we call a differentiated core. There's
<v Speaker 3>a solid inner core mostly iron and nickel, and that's
<v Speaker 3>surrounded by a churning, swirling liquid outer core, also mainly
<v Speaker 3>iron and nickel, but mixed with some lighter elements like
<v Speaker 3>soul for an oxygen. It's this dynamic internal structure that's
<v Speaker 3>absolutely critical for generating or its global magnetic field.
<v Speaker 2>Okay, solid inner, liquid outer.
<v Speaker 3>And this specific arrangement is what drives the geodynamo effect. Essentially,
<v Speaker 3>you have convexing currents within that liquid outer layer. Think
<v Speaker 3>of like boiling water, but with molten metal. These currents
<v Speaker 3>are driven by heat escaping from the salt inner core
<v Speaker 3>as it cools and crystallizes, and also by the planet's rotation.
<v Speaker 3>The Coriolis effects stirs things up, and this whole process
<v Speaker 3>generates a powerful expanse of magnetic field. This field stretches
<v Speaker 3>way out into space, forming this invisible protective bubble around
<v Speaker 3>our entire planet. We call it the magnetosphere. It's a
<v Speaker 3>truly amazing self sustaining system.
<v Speaker 2>So it's like an invisible shield. That's a good way
<v Speaker 2>to think about it constantly deflecting all this harmful stuff
<v Speaker 2>from the sun, charged particles exactly.
<v Speaker 3>It deflects harmful charged particles that are constantly blasted out
<v Speaker 3>by the Sun, especially during solar flares and chronal mass ejections.
<v Speaker 3>These solar winds, as they're called, are incredibly energetic streams
<v Speaker 3>of protons and electrons, and without that magnetospheric shield, they
<v Speaker 3>would just relentlessly strip away our atmosphere over geological time.
<v Speaker 2>Like a sand blaster.
<v Speaker 3>Yeah, that's a good analogy. Much like a powerful sand
<v Speaker 3>blaster eroding rock. It's this continuous, silent battle happening way
<v Speaker 3>above our heads. The magnetosphere acts like a bouncer, basically
<v Speaker 3>redirecting these high energy particles around Earth. Without this magnetic protection,
<v Speaker 3>our atmosphere, and along with it, the conditions for life
<v Speaker 3>would slowly but surely vanish. It's also why we get
<v Speaker 3>the auroras, the northern and Southern lights, that some of
<v Speaker 3>those deflected particles interacting with our atmosphere near the poles,
<v Speaker 3>a beautiful side effect of our planet's shield.
<v Speaker 2>Okay, that makes sense. So with that essential understanding of
<v Speaker 2>Earth's shield in mind, what about Mars. Does it have
<v Speaker 2>a similar life preserving magnetic field today? Because I mean,
<v Speaker 2>if it doesn't, that immediately points to a very different situation,
<v Speaker 2>doesn't it maybe one vulnerability of loss currently, No.
<v Speaker 3>It doesn't. Mars utterly lacks a global magnetic field today,
<v Speaker 3>certainly nothing like Earth's. This is a critical difference and
<v Speaker 3>a major reason why Mars is the cold, dry world
<v Speaker 3>we see now. However, and this is a really crucial
<v Speaker 3>piece of the puzzle. The evidence points to a very
<v Speaker 3>different pass from Mars too, from residual magnetization found embedded
<v Speaker 3>in the Martian crust. Essentially, you have rocks on the
<v Speaker 3>surface that still hold a Foffel magnetic signature. This signature
<v Speaker 3>dates back to when they first formed and cooled down
<v Speaker 3>billions of years ago in the presence of an active
<v Speaker 3>magnetic field. Scientists are quite confident that Mars did once
<v Speaker 3>possess such a global field.
<v Speaker 2>So it had a shield too early on, it.
<v Speaker 3>Seems so orbiting spacecraft like Mars Global surveyor actually mapped
<v Speaker 3>these magnetic anomalies in the crust. They confirmed that an
<v Speaker 3>ancient dynamo was active, likely for maybe the first billion
<v Speaker 3>years or so of Mars's history. And this ancient field
<v Speaker 3>was probably generated by a core structure similar to Earth's,
<v Speaker 3>meaning it likely had a soltid inner core and a
<v Speaker 3>liquid outer core capable of driving that dynamo.
<v Speaker 2>Okay, so it had one, but lost it. What are
<v Speaker 2>the implications of that loss?
<v Speaker 3>They're profound, truly profound. It marks a pivotal moment in
<v Speaker 3>Mars's story. Scientists generally hypothesize that the eventual loss of
<v Speaker 3>this magnetic field was a critical turning point, perhaps the
<v Speaker 3>critical turning point. Without that protective shield, the relentless solar
<v Speaker 3>wind would have had direct, unimpeded access to Mars's ancient, much.
<v Speaker 2>Thicker atmosphere, right, no more bouncer.
<v Speaker 3>Exactly, over millions, hundreds of millions of years, this energetic
<v Speaker 3>bombardment would have stripped that atmosphere away, particle by particle
<v Speaker 3>through processes like sputtering where particles get knocked off and
<v Speaker 3>ion pickup, where atmospheric gases get carried away by the
<v Speaker 3>solar wind. Think of it like a constant slow leak
<v Speaker 3>into space. This atmospheric loss, in turn, would have led
<v Speaker 3>directly to the rapid and irreversible loss of surface liquid water.
<v Speaker 3>As the atmospheric pressure dropped, water just couldn't stay liquid
<v Speaker 3>on the surface anymore. It would either freeze or subtlee
<v Speaker 3>may turn directly into gas and escape into space, or
<v Speaker 3>maybe retreat underground. It's this cascading chain of events starting
<v Speaker 3>deep inside the planet with the dying dynamo that ultimately
<v Speaker 3>led to the barren landscape we see today.
<v Speaker 2>Wow, so it all comes back to the core. This
<v Speaker 2>really raises that central question. Then, what exactly happened to
<v Speaker 2>Mars's internal engine? What switched off that planetary dynamo? What
<v Speaker 2>turned Mars from potentially vibrant and watery into the desert?
<v Speaker 2>It is now that's the core mystery, isn't it. And
<v Speaker 2>to answer that, we couldn't just look at the surface anymore.
<v Speaker 2>We had to go deeper, which is precisely why missions
<v Speaker 2>like Insight were conceived right precisely.
<v Speaker 3>Yeah, while missions like NASA's amazing Rover, Spirit, Opportunity, Curiosity,
<v Speaker 3>Perseverance have been fantastic surface geologists, you know, analyzing rocks
<v Speaker 3>and soil and orbiters like esay's exomrs trace gas orbit
<v Speaker 3>or study the water cycle, and NASA has made an
<v Speaker 3>end look specifically at an atmospheric loss. A fundamentally different
<v Speaker 3>kind of mission was needed to probe that core question,
<v Speaker 3>the question about the planets deep into We needed to listen, not.
<v Speaker 2>Just look, and that mission was NASA's Insight Lander. It
<v Speaker 2>touched down quite incredibly back in November twenty eighteen, landed
<v Speaker 2>in a region called Elysium Planitia, chosen because it's relatively
<v Speaker 2>flat geologically quiet, which is ideal for its sensitive instruments.
<v Speaker 2>Its primary goal, really groundbreaking, was to study seismic activity
<v Speaker 2>marsquakes as we call them. The aim was to reveal
<v Speaker 2>for the very first time the planet's internal structure, its crust,
<v Speaker 2>its mantle, and crucially its core. Insight listened patiently to
<v Speaker 2>Mars for four years, making its last contact in December
<v Speaker 2>twenty twenty two. Sadly its solar panels got too dusty
<v Speaker 2>to keep it powered. But it's data that continues to
<v Speaker 2>revolutionize our understanding. It's this treasure trope scientists are still
<v Speaker 2>digging through. Okay, so here's where it gets really interesting.
<v Speaker 2>In twenty twenty one, there was this seminal paper, a
<v Speaker 2>truly landmark study that came out of the Insight mission
<v Speaker 2>led by Simon Staylor and his colleagues. This paper gave
<v Speaker 2>us the very first direct look, the first robust measurement
<v Speaker 2>of Mars core. So, after all that anticipation, all that listening,
<v Speaker 2>what did they actually find? What was the initial verdict
<v Speaker 2>on Mars depth secret.
<v Speaker 3>Well, using that invaluable data from the marsquakes, those faint
<v Speaker 3>rumbles and tremors deep inside the planet, Stealer's team analyzed
<v Speaker 3>how the seismic waves traveled through Mars. Think of it
<v Speaker 3>like shouting into a canyon and timing the echoes. Different
<v Speaker 3>materials inside the planet reflect and transmit seismic waves differently. Okay,
<v Speaker 3>So by precisely timing how these marsquake echoes, specifically the
<v Speaker 3>Pea waves which are compressional waves and s ways the
<v Speaker 3>Shearer waves traveled from the quake's origin through the crust,
<v Speaker 3>the mantle, down into the core, maybe reflecting off internal boundaries,
<v Speaker 3>and then finally traveling back up to inside supersensitive seismometer
<v Speaker 3>called SACE, they could literally map the internal layers like
<v Speaker 3>a planetary sonogram. It was the first time we ever
<v Speaker 3>directly heard Mars's internal structure. Incredible, So what did that
<v Speaker 3>first map show? What did the core look like in
<v Speaker 3>that twenty twenty one study, Right, So, their in depth analysis,
<v Speaker 3>based on about a dozen of the larger marsquakes they
<v Speaker 3>had recorded by then, revealed a few key things. Some
<v Speaker 3>were a bit surprising at the time. They modeled a
<v Speaker 3>core with just a single liquid layer, basically a big
<v Speaker 3>molten ball of metal, and this core was surprisingly large.
<v Speaker 3>They estimated its radius at about eighteen hundred kilometers, which
<v Speaker 3>is roughly half of Mars's total radius, quite big for
<v Speaker 3>a planet Mars.
<v Speaker 2>Off the radius wow Yeah.
<v Speaker 3>And furthermore, it turned out to be less dense than
<v Speaker 3>you'd expect for a purely iron nickel core like Earth's.
<v Speaker 3>Is mostly this density deficit, which they inferred from how
<v Speaker 3>fast the seismic waves traveled through it, strongly suggested it
<v Speaker 3>was rich in lighter elements, things like sulfur or oxygen
<v Speaker 3>carbon maybe hydrogen mixed in with the iron and nickel.
<v Speaker 2>And why is that important for lighter elements.
<v Speaker 3>Well, those lighter elements significantly affect the core's melting temperature
<v Speaker 3>if they lower it. That makes it much more likely
<v Speaker 3>for the core to stay liquid for longer, rather than
<v Speaker 3>solidifying quickly as the planet cools down over billions of years.
<v Speaker 3>So this was a crucial insight. It potentially explained how
<v Speaker 3>Mars might have kept a liquid core and maybe a
<v Speaker 3>dynamo going for some time. And though it's smaller than.
<v Speaker 2>Earth, okay, so large liquid less dens full of lighter elements,
<v Speaker 2>did they say anything about a solid inner core like Earth's.
<v Speaker 3>That's a really crucial detail from Staleler's paper, and it
<v Speaker 3>shows how careful science is. They did not explicitly rule
<v Speaker 3>out the possibility of a solid inner core. The authors
<v Speaker 3>themselves meticulously stated in the paper that the signal strength
<v Speaker 3>from the data they had at that time, and the
<v Speaker 3>specific types of seismic waves they could confidently analyze were
<v Speaker 3>simply not robust enough, not clear enough. They couldn't definitively
<v Speaker 3>identify the faint signals you'd expect from seismic waves crossing
<v Speaker 3>an intercore boundary. So it's an excellent first measurement, truly
<v Speaker 3>a monumental achievement, but they explicitly acknowledged its limitations and
<v Speaker 3>left room for further discoveries. It's at the stage, you know,
<v Speaker 3>waiting for more data or better techniques to perhaps see deeper.
<v Speaker 2>Right, And science is truly a journey, isn't it? Not
<v Speaker 2>just one destination. So while Staler's work was absolutely monumental,
<v Speaker 2>a groundbreaking first look, the story of Mars core or
<v Speaker 2>as you said, didn't stop there. Just recently, new even
<v Speaker 2>more refined results came out. This was from Hwixingbe and
<v Speaker 2>colleagues published in the journal Nature. And this took our
<v Speaker 2>understanding to a whole new level, didn't it. What did
<v Speaker 2>they uncover that was so significant building on that initial
<v Speaker 2>foundation laid by Staler's team.
<v Speaker 3>Yeah, this is a fantastic example of scientific progress in action.
<v Speaker 3>You see one study building directly on the previous one
<v Speaker 3>and also the power of persistent, clever data analysis. This
<v Speaker 3>latest study by Biling colleagues, they leveraged additional insight data
<v Speaker 3>data collected over a longer period after Staler's first analysis,
<v Speaker 3>So that meant a larger catalog of Mars quakes to
<v Speaker 3>work with, including some that were perhaps deeper or more energetic,
<v Speaker 3>sending clearer signals through the core. Okay, more data, more data, yes,
<v Speaker 3>But crucially they also employed some novel and highly sophisticated
<v Speaker 3>data analysis techniques, new ways of processing the signals. By
<v Speaker 3>carefully selecting specific types of seismic events, ones that happened
<v Speaker 3>at just the right distances from d site to maximize
<v Speaker 3>the chance of detecting faint reflections from deep within, and
<v Speaker 3>then expertly extracting an incredibly weak signal from what was
<v Speaker 3>often quite a lot of instrument noise, they managed something remarkable.
<v Speaker 3>It was like seismological detective work, filtering out all the
<v Speaker 3>background chatter to finally hear the planet's deepest whispers clearly.
<v Speaker 2>And what did those whispers tell them? What was the
<v Speaker 2>key finding?
<v Speaker 3>Their key finding was unambiguous. They identified the clear presence
<v Speaker 3>of a solid layer within the liquid Martian core. This
<v Speaker 3>wasn't just a subtle hint. It was the distinct solid
<v Speaker 3>inner core, and they even estimated its radius at approximately
<v Speaker 3>six hundred and ten kilometers.
<v Speaker 2>Six hundred and ten kilometers. How does that compare to
<v Speaker 2>the overall core size.
<v Speaker 3>Well, if the total core radius is around eighteen hundred kilometers,
<v Speaker 3>then six hundred and ten kilometers is a substantial fraction,
<v Speaker 3>about a third of the radius, or roughly fifteen percent
<v Speaker 3>of Mars's total radius is this solid inner core. This
<v Speaker 3>is a profound revision to our understanding. It shifts our
<v Speaker 3>model of Mars's interior from that simple, fully liquid core
<v Speaker 3>picture to a more complex, differentiated one, much more like
<v Speaker 3>Earth's structure.
<v Speaker 2>Okay, wow, so we thought it was just liquid and
<v Speaker 2>now we find this distinct solid part inside. That feels
<v Speaker 2>like a really big shift. What does this solid inner
<v Speaker 2>core actually mean for understanding Mars's history and crucially for
<v Speaker 2>that long loss magnetic field we talked about, Why is
<v Speaker 2>this particular detail solid inside liquid such a big deal?
<v Speaker 2>How does it connect to a planet's life support system? Well,
<v Speaker 2>what's truly profound here is the implication this discovery carries.
<v Speaker 3>It's huge. The very presence of a solid inner core
<v Speaker 3>tells us definitively that crystallization is happening. Solidification is taking
<v Speaker 3>place as the planet cools over geological time. This process
<v Speaker 3>where liquid metal slowly solidifies at the center and in
<v Speaker 3>doing so releases latent heat and lighter elements. This process
<v Speaker 3>is absolutely critical for a planet like Earth to generate
<v Speaker 3>and sustain its magnetic field for billions of years. It's
<v Speaker 3>essentially the engine that drives the planetary dynamo.
<v Speaker 2>Ah. Okay, so the solidifying process itself is the key.
<v Speaker 3>Yeah, exactly. To elaborate a bit on its magnificance, a
<v Speaker 3>core structure with both a solid inner part and a
<v Speaker 3>liquid outer layer is fundamentally much more like Earth's setup
<v Speaker 3>On Earth, It's precisely the temperature differences and the chemical
<v Speaker 3>change is happening at that boundary between the solid inner
<v Speaker 3>core and the swirling liquid outer core, plus the heat
<v Speaker 3>flowing out into the surrounding mantle that drive the vigorous
<v Speaker 3>convection currents in that liquid outer layer. As the core
<v Speaker 3>cools iron crystallizes onto the inner core, this process releases lighter,
<v Speaker 3>more buoyant elements into the liquid outer core, and these
<v Speaker 3>lighter fluids than rise, creating convection like a lava lamp effect,
<v Speaker 3>but with molten metal. These convection currents, this organized movement
<v Speaker 3>of molten electrically conducting metal, coupled with the planet's spin,
<v Speaker 3>are the engine from the dynamo that generates a planetary
<v Speaker 3>magnetic field. Therefore, this new discovery of a solid inner
<v Speaker 3>core on Mars makes it significantly more likely, much more plausible,
<v Speaker 3>that a robust dynamo capable of producing a protective magnetic field,
<v Speaker 3>was indeed active on Mars early in its own and
<v Speaker 3>perhaps it was sustained for significant period. It provides that
<v Speaker 3>missing ingredient, that earth like structure needed for a strong,
<v Speaker 3>long lasting dynamo.
<v Speaker 2>And for you listening right now, this gives us a
<v Speaker 2>much clearer, much more scientifically solid pathway for Mars to
<v Speaker 2>have once had the conditions needed for a thicker atmosphere
<v Speaker 2>and as a result that abundant flowing liquid water on
<v Speaker 2>its surface that the geology points to. It connects the
<v Speaker 2>deep hidden internal processes of the planet directly to the
<v Speaker 2>surface conditions we were talking about earlier. It closes a
<v Speaker 2>major loop in our understanding of how Mars could have
<v Speaker 2>been so different back then.
<v Speaker 4>Okay, so when we hear about one study like Stalers
<v Speaker 4>in twenty twenty one initially suggesting a fully liquid core,
<v Speaker 4>and then another one like Bins just recently reporting a
<v Speaker 4>solid inner core, it might, you know, at first glance,
<v Speaker 4>sound like a scientific argument, maybe even a controversy or contradiction.
<v Speaker 3>That's absolutely not.
<v Speaker 4>What's happening here is that this is actually a really
<v Speaker 4>wonderful illustration of how science actually works. It's self correcting
<v Speaker 4>progressive nature.
<v Speaker 3>Absolutely not a controversy, noe, not in the sense of
<v Speaker 3>a fight. It's actually an excellent and incredibly common example
<v Speaker 3>of the iterative nature of science how data collection and
<v Speaker 3>analysis evolve. Staler's initial findings in twenty twenty one were,
<v Speaker 3>without question groundbreaking. A huge first step. They provided the
<v Speaker 3>first solid constraints on Mars's core size and state, a
<v Speaker 3>monumental achievement, giving us that first internal glimpse. But as
<v Speaker 3>they themselves very carefully noted in their paper, the data
<v Speaker 3>they had available at that specific time and the methods
<v Speaker 3>they used just didn't have the necessary signal strength or clarity.
<v Speaker 3>They couldn't definitively confirm or deny the existence of a
<v Speaker 3>solid inner core. They were very clear about that limitation,
<v Speaker 3>which is just part of good scientific.
<v Speaker 2>Practice, right. They pointed out what they couldn't see yet exactly.
<v Speaker 3>So it's not about one being right and the other wrong.
<v Speaker 3>Staler's twenty twenty one work was the best possible model
<v Speaker 3>based on the data and techniques available. Then the new
<v Speaker 3>study by billion colleagues, well, they benefited from more data,
<v Speaker 3>newer data accumulated as Insight kept listening recording more marsquakes,
<v Speaker 3>maybe some deeper or stronger ones. And crucially they applied
<v Speaker 3>more refined novel data analysis techniques. They basically found clever
<v Speaker 3>ways to pull out those weaker, more subtle seismic signals
<v Speaker 3>stignals that were previously either buried in the noise or
<v Speaker 3>just beyond the detection capability of the earlier methods. It's
<v Speaker 3>his continuous process. Initial models based on the best evidence
<v Speaker 3>of the time, get tested, refined, expanded upon as new
<v Speaker 3>information comes in and as the analytical tools themselves get better.
<v Speaker 3>This is precisely how scientific understanding deepens. It becomes more
<v Speaker 3>precise over time, with each new study building carefully on
<v Speaker 3>the last one.
<v Speaker 2>It's a fantastic example of the scientific method in action,
<v Speaker 2>isn't it Not like a Suiden Eureka moment, but this persistent,
<v Speaker 2>incremental build up of knowledge, and you see this iterative
<v Speaker 2>process even within related research groups you mentioned. Even Staler's
<v Speaker 2>initial model was revised slightly in twenty twenty three.
<v Speaker 3>That's right by Ari Hamuel from University of Pariseta and
<v Speaker 3>his column. Their updates help to further reconcile insight seismic
<v Speaker 3>findings with other existing evidence about Mars's core size and density.
<v Speaker 3>Often these refinements incorporate other types of geophysical data too,
<v Speaker 3>constraints from Mars's gravity field measurements or its rotation, things
<v Speaker 3>learned from orbiters. This ongoing dialogue, this constant refinement of
<v Speaker 3>models and theories as new data comes in. It's absolutely
<v Speaker 3>central to how science progresses. It's really collaborative, not confrontational,
<v Speaker 3>a shared journey towards getting a clearer picture.
<v Speaker 2>Okay, so this isn't the final word, the absolute end
<v Speaker 2>of the story about Mars's core, but it's a major
<v Speaker 2>new chapter, a really significant one. What does this new discovery,
<v Speaker 2>this confirmation of a solid inner core mean for the
<v Speaker 2>scientific community moving forward? What can we expect next in
<v Speaker 2>Martian science? Now this piece is in place.
<v Speaker 3>Oh, this result is absolutely going to have a significant
<v Speaker 3>and I think very exciting impact within the planetary science community.
<v Speaker 3>We could definitely expect more reanalyzies of the entire insight
<v Speaker 3>data set. That's almost guaranteed. Scientists will be scrutinizing these
<v Speaker 3>new methods used by Bees and colleagues looking for independent confirmation.
<v Speaker 3>They'll likely apply these techniques to other seismic events, maybe
<v Speaker 3>look at different types of seismic waves to see if
<v Speaker 3>they can consistently detect that solid inncore signal and maybe
<v Speaker 3>refine its properties even further. The goal is always to
<v Speaker 3>solidify a finding like this through multiple lines of evidence,
<v Speaker 3>multiple analyzes.
<v Speaker 2>Makes sense, check the work basically.
<v Speaker 3>Exactly, check the work, try different approaches, and beyond just
<v Speaker 3>the seismology, there will be thorough discussion about the broader
<v Speaker 3>geological and geophysical context. Researchers will be looking in detail
<v Speaker 3>at how this new model of Mars's interior solid inner
<v Speaker 3>core liquid outer core fits with everything else we know.
<v Speaker 3>That includes geochemical models of Mars's bulk composition, the precise
<v Speaker 3>gravity field data from orbiters that tells us about mass
<v Speaker 3>distribution inside the planet, and those previous studies of the
<v Speaker 3>crustal magnetic anomalies. This collaborative, cross disciplinary process is how
<v Speaker 3>we strengthen our collective understanding of planetary evil. It ensures
<v Speaker 3>the model makes sense in the big picture. It's honestly
<v Speaker 3>a very exciting time for Martian seismology and planetary science.
<v Speaker 3>It's prompting new theoretical models and definitely fueling further investigations
<v Speaker 3>into the red planet's deep past and maybe even its
<v Speaker 3>future evolution.
<v Speaker 2>So let's pull back for the big picture, then, the
<v Speaker 2>grand narrative of planetary science. Why is understanding the insight
<v Speaker 2>of Mars this newly revealed internal structure. Why is it
<v Speaker 2>so critical not just for Mars itself, but for our
<v Speaker 2>fundamental understanding of planets in general, you know broth here
<v Speaker 2>in our Solar System and maybe even worlds beyond.
<v Speaker 3>Yeah, this really raises an important question that goes way
<v Speaker 3>beyond just Mars. Understanding the interior structure of any planet
<v Speaker 3>in our Solar System is absolutely critical. It's fundamental if
<v Speaker 3>we want to develop robust, accurate theories about how these
<v Speaker 3>celestial bodies form in the first place, how they grow,
<v Speaker 3>and crucially, how they evolve over billions of years. The
<v Speaker 3>core really is the engine of planetary change. It influences
<v Speaker 3>everything from the geology on the surface to whether a
<v Speaker 3>planet can hold onto its atmosphere. Consider this before insights work,
<v Speaker 3>and especially before this latest discovery confirming the solid inner core.
<v Speaker 3>Models for Mars that suggested an internal structure very similar
<v Speaker 3>to or specifically the differentiated core, with both liquid and
<v Speaker 3>solid parts capable of powering a long lived dynamo. Well,
<v Speaker 3>they weren't generally favored. Many models lean towards Mars having
<v Speaker 3>cooled faster, maybe having a fully liquid core, or perhaps
<v Speaker 3>one with a different composition that just couldn't support a
<v Speaker 3>dynamo for as long as Earth's is run.
<v Speaker 2>So this discovery really changes that baseline assumption. It shifts
<v Speaker 2>the perspective dramatically. Yes, this confirmation of a solid inner
<v Speaker 2>core means Mars's early history might have been much more
<v Speaker 2>earth like deep down than we generally thought possible. And
<v Speaker 2>this knowledge helps us cackle these really fundamental, profound questions
<v Speaker 2>like how big does a rocky planet need to be
<v Speaker 2>to generate and sustain a protective magnetic field over billions
<v Speaker 2>of years? What are the keing re radients, the compositional factors,
<v Speaker 2>the thermal conditions required for a planet to maintain the
<v Speaker 2>habitable climate, an environment where liquid water can persist over
<v Speaker 2>those vast stretches of geological time. It pushes us to
<v Speaker 2>rethink the minimum requirements maybe for forming an earth like
<v Speaker 2>planetary system, and for you listening right now, this knowledge
<v Speaker 2>it stretches far beyond just our red neighbor, doesn't it.
<v Speaker 2>It directly feeds into our ongoing very ambitious search for
<v Speaker 2>habitable exoplanets, those world's orbiting distance stars. As we find
<v Speaker 2>more and more exoplanets, this detailed case study of Mars
<v Speaker 2>gives us crucial reference points what to look for. Perhaps
<v Speaker 2>it helps us better understand the precious rarity of Earth conditions,
<v Speaker 2>especially that long lived active geodynamo providing our essential shield.
<v Speaker 2>It really highlights what a truly unique, and you could
<v Speaker 2>say fortunate world, our home planet is still protected by
<v Speaker 2>its powerful internal engine humming along after four and a
<v Speaker 2>half billion years. So we're left with a much richer picture, now,
<v Speaker 2>a far more dramatic and ultimately a more nuanced story
<v Speaker 2>of Mars. It wasn't always it is just the cold,
<v Speaker 2>barren desert we see today, completely lacking that global magnetic protection.
<v Speaker 2>It seems it had a fighting chance, didn't it, an
<v Speaker 2>internal engine that was once very much alive.
<v Speaker 3>In kicking Precisely, we now have much stronger, more direct
<v Speaker 3>seismic evidence supporting it. Past Mars, that was a truly
<v Speaker 3>dynamic world, a world with an earth like core generating
<v Speaker 3>a powerful magnetic field, which in turn likely sustained a
<v Speaker 3>thicker atmosphere and allowed for very probably abundant flowing liquid
<v Speaker 3>water on its surface. Its transformation into the cold, dry
<v Speaker 3>desert planet we know today wasn't instantaneous, but it was
<v Speaker 3>this gradual yet profound planetary drama, a saga driven directly
<v Speaker 3>from its very core outwards as that internal engine eventually
<v Speaker 3>cool slowed down, and the dynamo dyet. It serves as
<v Speaker 3>this really powerful illustration how the internal processes of a planet,
<v Speaker 3>those hidden mechanics deep beneath the surface, ultimately dictate the
<v Speaker 3>surface environment and by extension, is potential for supporting life. Mars,
<v Speaker 3>in many ways, is a cautionary dale. It's a natural
<v Speaker 3>laboratory showing us what can happen when a planet loses
<v Speaker 3>the vital internal protections hashtash tag tag outrop.
<v Speaker 2>Wow, what an incredible journey we've taken today, Venturing from
<v Speaker 2>the dusty, familiar surface of Mars right down to its
<v Speaker 2>newly revealed core, a solid inner core, surprisingly earthlake. We've
<v Speaker 2>seen how this patiently gathered seismic data collected over years
<v Speaker 2>by insight, combined with ingenious refined analysis, can unravel mysteries
<v Speaker 2>millions and millions of miles away. It's just a testament,
<v Speaker 2>isn't it, to the power of scientific exploration and that
<v Speaker 2>relentless human drive to understand our universe, one planet, one
<v Speaker 2>core at a time. It's almost poetic really that after
<v Speaker 2>all these years of just gazing at Mars, sending rovers
<v Speaker 2>to taste soil, or finally getting to listen to its heartbeat.
<v Speaker 3>Yeah, this ongoing exploration of Mars interior, it really reminds
<v Speaker 3>us that the planets in our Solar System aren't just
<v Speaker 3>static objects hanging in space. They are dynamic worlds. They
<v Speaker 3>have complex, often dramatic histories. They're constantly evolving, constantly transforming
<v Speaker 3>over cosmic time scales. The Insight mission, even though it's
<v Speaker 3>now silent on the marsh and planes, it continues to
<v Speaker 3>speak volumes through its invaluable data. It's pushing us ever
<v Speaker 3>closer to understanding the dramatic saga of the red planet
<v Speaker 3>and really, by extension, our own place within the cosmos.
<v Speaker 3>It truly reshapes our understanding of how planets like ours evolve.
<v Speaker 2>So as we wrap up this exploration, maybe consider this
<v Speaker 2>Mars story. It's journey from a potentially vibrant, watery world
<v Speaker 2>shielded by a magnetic field, much like Earliers, perhaps to
<v Speaker 2>the dry, barren desert it is today. It's a stark reminder,
<v Speaker 2>isn't it, of how fragile planetary habitability it can actually be.
<v Speaker 2>It's this delicate balance of internal processes external forces, a
<v Speaker 2>kind of cosmic dance that can turn a world from
<v Speaker 2>blue and wet to red and dry over billions of years.
<v Speaker 3>And maybe ask yourself, what if lurking deep within other
<v Speaker 3>seemingly barren worlds we observe out there there are similar clues,
<v Speaker 3>clues to pass lives, past habitability, or maybe even the
<v Speaker 3>subtle potential for future transformations we haven't considered. Mars really
<v Speaker 3>asks us how truly unique is Earth state? And what
<v Speaker 3>other profound place planetary secrets are just waiting to be revealed,
<v Speaker 3>hidden beneath the surfaces of other worlds, just waiting for
<v Speaker 3>us to listen patiently to their whispers across the silence
<v Speaker 3>of space.
<v Speaker 2>Yousssssss