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: When you think about Mars, you know, the image that
Speaker 2: instantly pops into your head is the red planet. It's dusty,
Speaker 2: it's cold, desolate and just utterly profoundly dry.
Speaker 3: Right, It's the planet of rust, of a thin, wispy atmosphere,
Speaker 3: and we think of its surface as being carved by wind.
Speaker 2: Not water, and it's looked that way for well, for eons,
Speaker 2: billions of years. But here's the thing, the shift and
Speaker 2: perspective that we really need. Ancient Mars. It was dramatically,
Speaker 2: fantastically wet.
Speaker 3: Oh absolutely, it had water flowing, collecting and eroding in
Speaker 3: volumes that we are i mean only now really beginning
Speaker 3: to quantify.
Speaker 2: And that quantification that's the essential leap forward here, isn't
Speaker 2: it is?
Speaker 3: For decades the debate was really just centered on the
Speaker 3: existence of water, you know, was it there?
Speaker 2: We spent so long just looking for the smoking.
Speaker 3: Gun exactly, and now the question has shifted entirely. It's
Speaker 3: about scale, it's about structure. It wasn't just wet, it
Speaker 3: was and this is the keyword organized organized.
Speaker 2: What do you mean by that? Was it just random
Speaker 2: pooling or yeah.
Speaker 3: Well that's the question. Was it just isolated flash floods
Speaker 3: from say a meteor impact melting some ice, or was
Speaker 3: it sustained, integrated, almost earth like hydrology.
Speaker 2: And that is precisely what we are deep diving into today.
Speaker 2: We have this foundational news study from scientists at the
Speaker 2: University of Texas at Austin, UT Austin, and it's just
Speaker 2: been published in the Proceedings of the National Academy of Sciences.
Speaker 3: And this isn't just another paper confirming water. We're so
Speaker 3: far beyond that now.
Speaker 2: This is the first systematic, truly comprehensive mapping of Mars's
Speaker 2: ancient major river basins, it's watersheds. It's giving us a
Speaker 2: colossal measure of their past power.
Speaker 3: So our mission here is to take this new high
Speaker 3: tech planetary cartography and really use it to gain insight
Speaker 3: into three crucial areas. First, just the sheer, almost unimaginable
Speaker 3: volume of water ancient Mars held, and like we said,
Speaker 3: how it was organized. Second, we need to understand the tools,
Speaker 3: the really ingenious techniques combining old data with new imagery
Speaker 3: that scientists used to map rivers that vanished billions of
Speaker 3: years ago. Fine, Finally we have to tackle the most
Speaker 3: compelling mystery that all this new evidence raises. We're going
Speaker 3: to review the current scientific consensus on where all that
Speaker 3: water went.
Speaker 2: Okay, let's unpack this. Then we're talking about an immense
Speaker 2: planetary plumbing system, one that's been completely silent, dormant for
Speaker 2: geological ages. So to set the scale for you right
Speaker 2: at the top, here's the initial shock factor nugget from
Speaker 2: this study. This first of is kind mapping identified major
Speaker 2: drainage systems that reduced and estimated get this, twenty eight
Speaker 2: thousand cubic kilometers of sediment.
Speaker 3: Twenty eight thousand cubic kilometers. I mean, that is a
Speaker 3: number that forces us to completely recalibrate our models of
Speaker 3: early Mars.
Speaker 2: It's not just little adjustment.
Speaker 3: No, not at all. We are not talking about mere
Speaker 3: streams or temporary ponds. We are talking about Earth scale,
Speaker 3: continental river systems, systems capable of eroding and transporting that
Speaker 3: mind boggling volume of material across vast distances on another world.
Speaker 2: Just to give you an idea of that size, twenty
Speaker 2: eight thousand cubic kilometers is roughly enough sediment to completely
Speaker 2: bury the state of Texas. Wow, to bury it under
Speaker 2: a layer of dirt one hundred.
Speaker 3: Feet deep one hundred feet.
Speaker 2: That's the sheer scale of the erosional power we are
Speaker 2: dealing with. So, okay, we're moving from this general abstract
Speaker 2: idea of water to the specific organization and structure of
Speaker 2: these water systems. We know the water was there, but
Speaker 2: what is the organization to that water tell us about
Speaker 2: the climate on ancient mars. I think this is where
Speaker 2: the new study really provides the critical insight.
Speaker 3: It's the difference between finding, say a small isolated stream
Speaker 3: bed in the desert right that might have been caused
Speaker 3: by one single heavy rain. It's the difference between that
Speaker 3: and mapping the entire Amazon River basin, which requires which
Speaker 3: requires thousands, maybe millions of years of continuous predictable climate patterns.
Speaker 3: And doctor Timothy A. Gouge, who led the research, he
Speaker 3: encapsulated this finding perfectly. He said that while we've known
Speaker 3: for a long time there were rivers on Mars, he said,
Speaker 3: and I'm quoting here, we really didn't know the extent
Speaker 3: to which the rivers were organized in large drainage systems
Speaker 3: at the global scale.
Speaker 2: Okay, let's dig into that. Why does that organization that structure,
Speaker 2: Why does it change the entire debate? Why is it
Speaker 2: such a monumental leap forward compared to just finding more
Speaker 2: evidence of flow.
Speaker 3: Because organization implies, well, it implies sustained, consistent hydrological cycles.
Speaker 2: Okay, an actual cycle like on Earth, exactly like on Earth.
Speaker 2: Think about our planet. When you see a massive dendritic.
Speaker 3: Water dendritic meaning tree like right.
Speaker 2: Like brandecisely, where smaller streams feed into tributaries, which then
Speaker 2: feed into major rivers which eventually empty into an ocean.
Speaker 2: That whole geological structure, it's the accumulated result of millennia
Speaker 2: of stable weather. It means precipitation was consistent enough to
Speaker 2: feed the entire system, runoff was predictable, and the system
Speaker 2: itself was stable enough to carve deep, integrated channels over
Speaker 2: a very very long time.
Speaker 3: So if the water was only caused by these random
Speaker 3: episodic events like a massive asteroid impact melting a bunch
Speaker 3: of ice, or a huge volcano going off. You just
Speaker 3: wouldn't get that integrated structure, would you. You wouldn't not
Speaker 3: at this scale. Those chaotic episodic events they create isolated
Speaker 3: channels or massive outflow features. Sure we see those on Mars,
Speaker 3: but they don't produce a sprawling, globally scaled network of
Speaker 3: interconnected systems that drain thousands of square kilometers in a
Speaker 3: coordinated way. This kind of integrated system, it confirms the
Speaker 3: presence of a climate that'd sustain large scale, stable river
Speaker 3: flow over long periods, and that makes the ancient planet
Speaker 3: much more earth like than some of the colder, dryer
Speaker 3: models previously suggested.
Speaker 2: And it's important to note these researchers weren't just looking
Speaker 2: for small, localized streams. They intentionally set a very high
Speaker 2: bar for what even qualified as a system worth mapping.
Speaker 3: That's a crucial point. They were specifically hunting for the
Speaker 3: planetary heavyweights.
Speaker 2: So what was the threshold to define a scale?
Speaker 3: They established a specific methodological threshold for inclusion. They only
Speaker 3: mapped drainage systems that exceeded one hundred and five square
Speaker 3: kilometers in surface area.
Speaker 2: That sounds incredibly precise one hundred and five. Why that
Speaker 2: specific area is it arbitrary, Not at all.
Speaker 3: It's a crucial methodological anchor. One hundred and five square
Speaker 3: kilometers is a common baseline area used in geology for
Speaker 3: defining what qualifies as a large drainage system right here
Speaker 3: on Earth.
Speaker 2: Ah, so the using our own planet is the yardstick.
Speaker 3: Exactly. By using this comparable terrestrial threshold, they weren't trying
Speaker 3: to capture every small that might have been created by
Speaker 3: some seasonal melt. They were systematically looking for features that
Speaker 3: qualify as major rivers, as large scale drainage basins, the
Speaker 3: kind of systems that define the regional climate and geology
Speaker 3: of a planet.
Speaker 2: So it ensures that what they're studying on Mars is
Speaker 2: comparable in scale and in its implications to a significant
Speaker 2: river system we'd recognize today.
Speaker 3: Right by using that one hundred and five scare kilometer standard,
Speaker 3: they are essentially saying, if the system were on Earth,
Speaker 3: it would be a major hydrological feature we would study
Speaker 3: in depth. It forces the conversation away from any marginal,
Speaker 3: maybe temporary water activity.
Speaker 2: It puts the focus squarely on the systems that did
Speaker 2: the heavy lifting, the ones that really shape the surface.
Speaker 3: It absolutely does, and it supports a central tenet in
Speaker 3: geology we call uniformitarianism.
Speaker 2: The present is the key to the past.
Speaker 3: The very same idea, The same natural laws and processes
Speaker 3: that operate today operated in the past. So if a
Speaker 3: system of a certain size requires a sustained climate here
Speaker 3: on Earth, it almost certainly required a sustained climate there
Speaker 3: on Mars.
Speaker 2: And the systematic approach also meant they had to define
Speaker 2: exactly what components constituted an organized system. They weren't just
Speaker 2: looking for wiggly lines on a map.
Speaker 3: That's right. A watershed is a holistic unit. It's not
Speaker 3: just a single channel. So they listed four key components
Speaker 3: they needed to successfully map and link across these vast
Speaker 3: areas to declare a system organized.
Speaker 2: And you know, major, what were those four defining components?
Speaker 3: Okay, so first the river systems themselves, that's the main channels,
Speaker 3: the smaller tributaries flowing into them, that whole dendritic network
Speaker 3: structure we talked.
Speaker 2: About the branches of the tree right.
Speaker 3: Second, the water deposit systems. These are the region often
Speaker 3: big sedimentary planes where the water lost its speed and
Speaker 3: started to deposit its carried load of sediment.
Speaker 2: So the source in the sink the beginning and the
Speaker 2: end of the line exactly.
Speaker 3: Third, the outlet canyons. These were often dramatic, high energy
Speaker 3: exit points where massive volumes of water estaped a basin,
Speaker 3: potentially flowing out to the vast north than lowlands of Mars.
Speaker 3: And the fourth piece and fourth the lakes and valley networks.
Speaker 3: These represent the temporary or in some cases long term
Speaker 3: reservoirs where water accumulated before either evaporating or flowing out
Speaker 3: through one of those outlet canyons.
Speaker 2: It's just fascinating that they needed to find all four
Speaker 2: of those elements connected together. That really demonstrates an integrated structure.
Speaker 2: It does by linking all those arteries and veins together
Speaker 2: across these huge areas, they essentially move the needle from okay,
Speaker 2: Mars had water to Mars had a functioning planetary scale hydrological.
Speaker 3: Cycle, and it confirms a period of Martian history where
Speaker 3: precipitation and surface conditions were just fundamentally different. To sustain
Speaker 3: sixteen of these massive systems requires more than just occasional melt.
Speaker 3: It requires a warm enough surface and a dense enough
Speaker 3: atmosphere for water to flow, collect and erode across enormous distances.
Speaker 3: It confirms a vast, ancient and very active history for
Speaker 3: the planet.
Speaker 2: Now we get to a part of this that I
Speaker 2: find truly intriguing. Here's where it gets really technical and
Speaker 2: I think really inspiring. How exactly do scientists map the
Speaker 2: beds and channels of rivers that vanished literally billions of
Speaker 2: years ago, right, rivers that are now potentially buried under
Speaker 2: shifting Martian dust or thick lava fields. Are these massive
Speaker 2: wind blown deposits. We are relying entirely on remote sensing,
Speaker 2: on orbiting instruments for this historical reconstruction, and.
Speaker 3: This specific mapping effort is just a masterclass in combining
Speaker 3: different types of orbital data. It's really clever. To reconstruct
Speaker 3: ancient waterflow. You need two crucial, high precision pieces of information.
Speaker 3: You need to know where the ground is so extreme
Speaker 3: precision on altitude topography, the topography exactly, and you need
Speaker 3: a high resolution visual proof of what is actually on
Speaker 3: the surface.
Speaker 2: Okay, let's start with that foundational data set. The altitude component.
Speaker 2: The study relies heavily on an instrument called MOLA.
Speaker 3: Yes, the Mars Orbiter Laser e Limiter MLLA was a
Speaker 3: primary instrument on board NASA is Mars Global Surveyor, which
Speaker 3: operated successfully from nineteen ninety seven all the way to
Speaker 3: two thousand and six.
Speaker 2: So this is legacy technology we're talking about.
Speaker 3: It is, and it's a revolutionary piece of legacy technology.
Speaker 3: MLA works by firing a laser pulse down at the
Speaker 3: Martians surface and then timing exactly how long it takes
Speaker 3: for that pulse to bounce back to the spacecraft.
Speaker 2: So it's basically like a super precise tape measure from space.
Speaker 3: That's a great way to put it. By tracking millions
Speaker 3: and millions of these pulses globally, you can calculate the
Speaker 3: distance and map the topography of Mars with extraordinary precision.
Speaker 2: So EMILA provides the bedrock map. It defines the continental divides,
Speaker 2: the lowest points, the high points. Crucially, it tells us
Speaker 2: which way water would have flowed just based on.
Speaker 3: Gravity exactly right. You simply cannot define a watershed without
Speaker 3: incredibly detailed altitude data. The sheer precision of MLA, which
Speaker 3: is often capable of measuring altitude differences down to the
Speaker 3: meter or even submeter scale.
Speaker 2: That's incredible, it is.
Speaker 3: And that's what allowed the scientists to mathematically model the subtle,
Speaker 3: faint gradients of a four billion year old riverbed that
Speaker 3: might have been partially eroded or buried. It defines the
Speaker 3: pass of least resistance for every theoretical drop of water
Speaker 3: across the entire Martian surface.
Speaker 2: So MLA provides the mathematical framework for the flow paths.
Speaker 2: But altitude data alone doesn't prove that a river was
Speaker 2: actually there right, or that the feature wasn't carved by
Speaker 2: something else like lava, an excellent point. You need the
Speaker 2: visual confirmation, the proof that the flow was indeed fluvial
Speaker 2: water based, and that's where the CTX, the context camera
Speaker 2: comes in.
Speaker 3: Yes, the Context Camera is currently orbiting Mars on board
Speaker 3: the Mars Reconnaissance.
Speaker 2: Orbiter or MRO, which is still active.
Speaker 3: Still very active, and CTX is critical because of its scale. Now,
Speaker 3: there are other cameras on MRO that take higher resolution snapshots,
Speaker 3: like the famous high Rise camera, but ctx's distinction is
Speaker 3: its sheer volume of data and its medium resolution coverage.
Speaker 3: It has achieved nearly complete coverage of the entire red planet.
Speaker 2: So MLA tells you where to look for a drop
Speaker 2: in elevation, and CTX provides the high resolution imagery you
Speaker 2: need to actually identify the erosional features along.
Speaker 3: That path precisely. CTX confirms the geological reality. It allows
Speaker 3: researchers to identify the detailed structures. You can see the
Speaker 3: actual river bends, the meanders, You can see layered sedimentary
Speaker 3: deposits on the valley floors. You can see those subtle
Speaker 3: dendritic or treelike branching patterns of the valley networks that
Speaker 3: are so characteristic of organized water erosion.
Speaker 2: The combination is just so powerful.
Speaker 3: It really is. You use EMLA to trace the flow direction,
Speaker 3: and then you zoom in with CTX to confirm that
Speaker 3: the features along that path are indeed ancient river channels.
Speaker 2: And the beauty of it, as you said, is that
Speaker 2: this study synthesizes data separated by decades. It really proves
Speaker 2: the continuing value of NASA's long term investments in these missions.
Speaker 3: Absolutely, the data from MARS Global Surveyor is still generating
Speaker 3: groundbreaking science today.
Speaker 2: But how do you actually reconcile and overlay these massive,
Speaker 2: complex data sets. This is where the specifics software comes in.
Speaker 2: The source mentions. They used RGIS pro, and.
Speaker 3: This is an important detail for you the listener to note.
Speaker 3: RGIS pro is a commercial industry standard geographic information system
Speaker 3: a GIS. It's used by cartographers, city planners, geologists all
Speaker 3: over the world for Earth.
Speaker 2: So it's off the show software it is.
Speaker 3: And the fact that planetary scientists use this same software
Speaker 3: underscores the universality of their methods. They're using the same
Speaker 3: tools to map mars that someone might use to map
Speaker 3: a new highway system in Ohio.
Speaker 2: So how does that software bridge the gap BETWEENMAS data
Speaker 2: and ctx's images.
Speaker 3: It allows for seamless data layer integration in a GIS.
Speaker 3: You can treat MLA's topography data as one massive layer
Speaker 3: that's your elevation map. Then you can overlay ctx's visual
Speaker 3: imagery as a second layer right on.
Speaker 2: Top of it, and you can add more layers. Isome?
Speaker 3: Oh yeah, you could add a third layer for mineral mapping,
Speaker 3: which we'll get to later, a fourth layer defining those
Speaker 3: hundred and five square kilometer catchment boundaries. And rgis pro
Speaker 3: allows researchers to define perarameters. You can tell it show
Speaker 3: me all the features from the CTX images that exhibit
Speaker 3: dendritic patterns A and D whose lowest point connects to
Speaker 3: the mathematically predicted flow path we derived from the MLLA data.
Speaker 2: So it automates the search in a way.
Speaker 3: It makes the search systematic, objective and reproducible. It moves
Speaker 3: planetary geology into this new era of verifiable cartography using
Speaker 3: the exact same tools we use to manage resources right
Speaker 3: here on Earth.
Speaker 2: And this systematic, rigorous mapping methodology is what gives these
Speaker 2: hard numbers their weight, their authority. So let's shift our
Speaker 2: focus now entirely to the tangible results, the specific measurements,
Speaker 2: and the sheer impact of these ancient river systems on
Speaker 2: the Martian surface.
Speaker 3: Okay, the findings derived from this MLACTX fusion are remarkably clear.
Speaker 3: The researchers successfully mapped sixteen highly organized drainage systems that
Speaker 3: exceeded that one hundred and five square kilometer baseline, fifteen
Speaker 3: of them sixteen. And these are not just suggestions of waterways.
Speaker 3: They are now the ignore the knowledge major integrated continental
Speaker 3: scale hydrological features of ancient Mars.
Speaker 2: And once again that sediment volume twenty eight thousand cubic
Speaker 2: kilometers in material I've spent some more time on this number,
Speaker 2: because it really is the core measure of the water's power.
Speaker 2: Can we try and quantify that volume with some more
Speaker 2: vivid earth based analogies.
Speaker 3: We have to, it's the only way to grasp it.
Speaker 3: The sheer volume moved by just these sixteen systems, it's
Speaker 3: comparable to the mass of a small terrestrial mountain range.
Speaker 3: Instead of being lifted up, it was transported across the surface. Wow,
Speaker 3: here's another way to think about it. If you took
Speaker 3: all the water in Lake Superior, which is the largest
Speaker 3: of the Great Lakes by volume, the sediment moved by
Speaker 3: these Martian systems is equivalent to filling Lake Superior approximately
Speaker 3: three times over with pack dirt and rock.
Speaker 2: Three Lake Superiors worth of dirt just moved by water.
Speaker 3: That is a stunning measure of the erosional work done
Speaker 3: by Martian water during its wet periods.
Speaker 2: That is a staggering amount of material to move. It's
Speaker 2: so hard to imagine that level of fluvial erosion on
Speaker 2: a planet we think of is static and frozen. It is,
Speaker 2: but the context becomes even sharper when we look at
Speaker 2: the relative contribution of these sixteen systems to the total planetary.
Speaker 3: History, which brings us to the forty two percent figure.
Speaker 2: Right.
Speaker 3: The study concluded that these sixteen map systems comprise approximately
Speaker 3: forty two percent of the total flowing sediment volume across
Speaker 3: all of ancient Mars, and this is arguably the most
Speaker 3: crucial takeaway regarding the nature of Martian hydrology.
Speaker 2: Okay, let's stop there and really analyze that forty two percent.
Speaker 2: If Mars had potentially thousands of smaller, unorganized streams, creeks,
Speaker 2: and flash flood events, which we know it did, how
Speaker 2: can just sixteen large systems account for nearly half of
Speaker 2: the planet's total fluvial work.
Speaker 3: It speaks directly to the efficiency and the duration of
Speaker 3: the flow.
Speaker 2: In those systems.
Speaker 3: The power was concentrated, highly concentrated. Think about it, sixteen
Speaker 3: systems doing almost half the work. That means these specific
Speaker 3: systems were disproportionately powerful. They had to have operated consistently,
Speaker 3: efficiently and for a very very long time. It's strongly
Speaker 3: suggests that while episodic water events might have initiated some
Speaker 3: erosion here and there, the bulk of the planet's surface
Speaker 3: sculpting was done by these massive integrated drainage systems.
Speaker 2: And those systems would require a stable climate.
Speaker 3: Regime, a sustained water cycle, perhaps involving rain or snow,
Speaker 3: something to keep them flowing for potentially millions of years.
Speaker 2: So instead of a picture where water was just kind
Speaker 2: of everywhere, carding millions of small gullies, the picture shifts.
Speaker 2: He becomes one where water was highly concentrated in a
Speaker 2: few dominant continental basins that really dictated the planet's geological evolution.
Speaker 3: Precisely, if on Earth forty two percent of all the
Speaker 3: fluvial work were done by only sixteen rivers you know,
Speaker 3: the Amazon, the Nile, the Mississippi, and a few others,
Speaker 3: that would imply a global uniformity in topography and precipitation
Speaker 3: that we just don't see. The fact that the Martian
Speaker 3: system is so concentrated suggests one of two things. Either
Speaker 3: Martian topography was incredibly efficient at funneling precipitation into a
Speaker 3: small number of giant basins, or the global climate was
Speaker 3: remarkably stable, allowing only the largest systems to operate long
Speaker 3: enough to accumulate that massive sediment volume.
Speaker 2: That concentration of power is immense, and it must offer
Speaker 2: important constraints for climate modelers, For the people trying to
Speaker 2: recreate what the ancient Martian atmosphere must have been like
Speaker 2: to sustain these giants.
Speaker 3: Absolutely, it narrows the possibilities.
Speaker 2: The study also had a specific finding about the role
Speaker 2: of the outlet canyons, those dramatic exit points of these systems.
Speaker 3: Yes, they quantified the impact of these high energy features,
Speaker 3: and they discovered that the outlet canyons, the points where
Speaker 3: large bodies of water like lakes breached or overflowed, contributed
Speaker 3: approximately twenty four percent of the global river sediment amount
Speaker 3: on ancient Mars.
Speaker 2: Okay, let's put this two numbers together. We have forty
Speaker 2: two percent from the sustained large scale river flow within
Speaker 2: the basins and twenty four percent from just the outlet canyons. Right,
Speaker 2: that twenty four percent implies massive focus potentially catastrophic flows
Speaker 2: where the water exited the basin. How do we reconcile
Speaker 2: those two things? Does this mean Mars was both sustained
Speaker 2: and catastrop I.
Speaker 3: Think it paints a very dynamic picture. The forty two
Speaker 3: percent confirms the consistency the long, slow work of erosion
Speaker 3: and transport inside the basin, But the twenty four percent
Speaker 3: from the canyon suggests that these basins, which likely held
Speaker 3: massive lakes, occasionally breached or overflowed in huge, violent volumes.
Speaker 2: So the system would fill up slowly over time.
Speaker 3: Exactly, it implies that the water flowed consistently filling up giant,
Speaker 3: long lived lakes, which then sometimes reached a catastrophic tipping
Speaker 3: point of discharge. These canyon exits acted as high speed funnels,
Speaker 3: transporting massive amounts of material from the interior basins down
Speaker 3: to the northern lowlands, and that likely contributed to the
Speaker 3: formation of whatever ancient oceans or major bodies of water
Speaker 3: may have existed there.
Speaker 2: So slow accumulation punctuated by high speed discharge it suggests
Speaker 2: the Martian water cycle wasn't just stable, it was also
Speaker 2: capable of producing these immense, focused floods at the termination
Speaker 2: points of these megasystems.
Speaker 3: It makes a lot of sense. Imagine a massive reservoir
Speaker 3: filling slowly over a thousand and years, then suddenly breaching
Speaker 3: a natural dam. The consistent work of filling it is
Speaker 3: the forty two percent. The dramatic breach is the twenty
Speaker 3: four percent.
Speaker 2: It confirms a truly powerful and very active hydrological cycle
Speaker 2: operating in an immense scale. Before we move on to
Speaker 2: the great mystery of where it all went, Let's ground
Speaker 2: this new cartography in the context of the overwhelming evidence
Speaker 2: that already confirmed ancient liquid water dominated the Martian surface.
Speaker 2: That's right. This mapping is new in its scope, but
Speaker 2: it really builds on decades of geological and mineralogical proof.
Speaker 3: That's the key point. This study confirms the system was integrated,
Speaker 3: but the physical proof of water has been piling up
Speaker 3: since the Viking missions in the seventies, and it just
Speaker 3: escalated exponentially with the rovers.
Speaker 2: And that proof comes in two main forms, right, the
Speaker 2: shapes on the surface and the chemical residue less behind.
Speaker 3: The geomorphology and the mineralogy exactly.
Speaker 2: Let's start with the geomorphological landforms, the geological evidence of
Speaker 2: liquid movement. Besides these drainage systems, what are the class
Speaker 2: undeniable signs of past water that we see from orbit?
Speaker 3: Well, we see clear evidence of deltas. The most famous
Speaker 3: right now is the incredibly well preserved delta structure in
Speaker 3: Jesero Crater, which is exactly why the Perseverance rover is
Speaker 3: operating there. Delta's only form when a flowing river slows
Speaker 3: down rapidly and dumps its sediment load as it enters
Speaker 3: a large standing body of water. That means there had
Speaker 3: to have been a long lived lake or even a
Speaker 3: sea in that crater.
Speaker 2: What else?
Speaker 3: We also see massive outflow channels. These are immense scars
Speaker 3: on the surface, sometimes hundreds of kilometers wide. They're often
Speaker 3: associated with catastrophic flood events, likely from the rapid release
Speaker 3: of pressurized underground reservoirs.
Speaker 2: And on a smaller scale, we see smaller features too,
Speaker 2: don't we Oh.
Speaker 3: Yes, thousands of small scale features like gullies. You often
Speaker 3: find these on crater walls, and they may represent more
Speaker 3: recent seasonal flows or maybe just near surface ice melting.
Speaker 3: And maybe most evocative for suggesting large standing bodies of water,
Speaker 3: we see evidence of coastal light terraces. These are horizontal markings,
Speaker 3: almost like steps in the landscape, suggesting ancient shorelines where
Speaker 3: water stood still at a consistent level for extended periods,
Speaker 3: perhaps defining the boundaries of an ancient northern ocean.
Speaker 2: So those landforms tell a story of movement, stillness, and
Speaker 2: massive flooding. But the most undeniable proof I find comes
Speaker 2: from the chemical signatures. The mineralogical evidence that only forms
Speaker 2: in the presence of liquid water.
Speaker 3: The minerals are the chemical fingerprints of the water's composition
Speaker 3: in its history. They are the archives of that wet phase.
Speaker 2: And we found several key types identified by orbiters and
Speaker 2: then confirmed on the ground by rovers.
Speaker 3: We have first clays, or what geologists call phyllosilicates. These
Speaker 3: form when water interacts chemically with volcanic rock over prolonged periods.
Speaker 3: The very fact that they exist suggests relatively neutral or
Speaker 3: alkaline water conditions, which is potentially favorable for life.
Speaker 2: But Mars clearly changed because we also found minerals that
Speaker 2: suggest a highly acidic environment later on.
Speaker 3: That's right. We find vast deposits of sulfate minerals and carbonates.
Speaker 3: Sulfates in particular often precipitate out when water is acidic
Speaker 3: and evaporates rapidly.
Speaker 2: So the minerals themselves tell a story of climate change.
Speaker 3: They provide a geological timeline. They confirm that the Martian
Speaker 3: water cycle not only existed, but it also changed chemically
Speaker 3: as the planet cooled in its atmosphere thinned. You had
Speaker 3: clays forming early in a more benign environment than sulfates
Speaker 3: forming later in a harsher one.
Speaker 2: And of course, you can't talk about water evidence without
Speaker 2: mentioning the tiny infamous hematite.
Speaker 3: Blueberries, the favorite piece of evidence for so many people,
Speaker 3: these small spherical concretions of iron oxide. They were famously
Speaker 3: discovered by the NASA Opportunity Rover way back in two
Speaker 3: thousand and four, just scattered all over MERIDIANI planum.
Speaker 2: And they could only have formed in water.
Speaker 3: Hematite strongly indicates formation in the presence of water, likely
Speaker 3: as minerals precipitated out of a flowing, slightly acidic solution.
Speaker 3: They are the perfect small scale, undeniable proof of prolonged
Speaker 3: agueous activity on the surface.
Speaker 2: So okay, we have the geomorphological structures, we have the
Speaker 2: chemical signatures, and now we have the global map of
Speaker 2: sixteen giant river systems. This whole body of evidence leads
Speaker 2: us to the crucial timeline debate. When did all this
Speaker 2: incredible activity happen and for how.
Speaker 3: Long Mars formed with the rest of the Solar system
Speaker 3: roughly four point five billion years ago. The generally accepted
Speaker 3: wet period, what we call the noation period, occurred relatively
Speaker 3: early within the first billion years or so, but the specifics,
Speaker 3: especially as the stain that wet period was. That's still
Speaker 3: intensely debated.
Speaker 2: Let's elaborate on those two main schools of thought.
Speaker 3: So on one side you have scientists who argue for
Speaker 3: episodic periods of water. This model suggests that while water existed,
Speaker 3: warm and wet conditions were transient, they were a flash
Speaker 3: in the pan.
Speaker 2: So a frozen Mars with brief thows exactly.
Speaker 3: Perhaps massive impact events or intense volcanic eruptions released enormous
Speaker 3: amounts of greenhouse gases which temporarily warmed and thawed the surface.
Speaker 3: That would allow water to flow violently for maybe hundreds
Speaker 3: or thousands of years before the planet froze again into
Speaker 3: its default cold state.
Speaker 2: And the other site argues for a more sustained period.
Speaker 3: Yes, the argument for a lone longer period. This suggests
Speaker 3: that early Mars maintained a thick enough atmosphere and sufficient heat,
Speaker 3: probably via a CO two greenhouse effect, to sustain liquid
Speaker 3: water continuously for hundreds of millions of years.
Speaker 2: And this new study, with its sixteen large integrated systems
Speaker 2: that must lend some serious weight to that longer period model.
Speaker 3: It really does. It's hard to imagine carving those massive
Speaker 3: systems with just a few thousand years of flow here
Speaker 3: and there. It requires immense cumulative flow time.
Speaker 2: And the most recent data on this really pushes that timeline.
Speaker 2: I mean, it pushes it far into the planet's history,
Speaker 2: doesn't it.
Speaker 3: It does. The source mentions a twenty twenty two study
Speaker 3: that estimated Mars had liquid water as recently as two
Speaker 3: billion years ago.
Speaker 2: Two billion. That's more than halfway through the planet's history.
Speaker 3: It is a dunning longevity. If that timeline holds true,
Speaker 3: it suggests water persisted in significant quantities, perhaps protected in
Speaker 3: deep subsurface reservoirs or under thick ice sheets at the poles,
Speaker 3: far far longer than the original models predicted, and that
Speaker 3: dramatically changes the window in which life could potentially have
Speaker 3: existed on Mars.
Speaker 2: The narrative of ancient Mars has just completely shifted from
Speaker 2: a dry, dead desert to a dynamic world of roaring
Speaker 2: rivers and massive lakes. We know the environment was capable
Speaker 2: of supporting these sixteen megasystems that move twenty eight thousand
Speaker 2: cubic kilometers of sediment. It's a different planet. It's a
Speaker 2: completely different planet. So given this immense proof, the question
Speaker 2: remains the ultimate planetary murder mystery. Why did the water
Speaker 2: all go away? And why so completely?
Speaker 3: It's not one single event. It was almost certainly a
Speaker 3: cascade of failures. There are likely three interacting mechanisms that
Speaker 3: led to the collapse of the Martian hydrosphere, and we
Speaker 3: really need to examine each leading scientific hypothesis. Recognizing them,
Speaker 3: they probably reinforced each other.
Speaker 2: Okay, let's start with the big one, the one that
Speaker 2: dictates the fate of the entire planet. Hypothesis one the
Speaker 2: loss of the magnetic field and atmospheric stripping.
Speaker 3: This is the fundamental difference between Mores and Earth. For
Speaker 3: a planet to retain a thick atmosphere and liquid water,
Speaker 3: it has to protect itself from the solar wind.
Speaker 2: It needs a shield.
Speaker 3: It needs a shield. Earth does this with its global
Speaker 3: magnetic field its magnetosphere, which is generated by our churning
Speaker 3: molten core, are planetary dynamo.
Speaker 2: And Mars had this protection early in its life.
Speaker 3: Correct, it did, but Mars is a much smaller planet,
Speaker 3: and because of its size, its molten core cooled far
Speaker 3: sooner and much more rapidly than Earth's did. As that
Speaker 3: core solidified, the planetary dynamo shut down, and that led
Speaker 3: to the slow dissipation of the protective magnetic field, probably
Speaker 3: starting around four billion years ago.
Speaker 2: So what happens when that planetary shield is removed? When
Speaker 2: you turn off the.
Speaker 3: Umbrella, the planet's upper atmosphere becomes exposed to the relentless
Speaker 3: bombardment of intense solar and cosmic radiation, primarily the solar wind,
Speaker 3: which is it's a constant stream of charged particles flowing
Speaker 3: from the Sun, and it acts like a sand blaster
Speaker 3: on a molecular level. It physically strips away atmosphere gases,
Speaker 3: carbon dioxide, nitrogen, and critically water molecules, blasting them off
Speaker 3: into space over millions of years.
Speaker 2: And we can see this happening even today.
Speaker 3: We can current Mars orbiters like NASA's Maven mission, are
Speaker 3: designed specifically to study this. They still detect this stripping
Speaker 3: process happening today, confirming that a huge amount of Mars's
Speaker 3: early water simply escaped to the cosmos molecule by molecule.
Speaker 2: So we confirm that a significant amount of water was
Speaker 2: lost to space, which thinned the atmosphere dramatically, and that
Speaker 2: leads directly to the next consequence hypothesis to climate collapse.
Speaker 3: The thinning atmosphere acted as a trigger for a catastrophic
Speaker 3: climate shift. Early Mars relied on gases, likely carbon dioxide
Speaker 3: and maybe some methane to create a green house effect
Speaker 3: that kept the surface warm enough for.
Speaker 2: Liquid water the insulation blanket.
Speaker 3: That's it exactly. As the magnetic field loss accelerated the
Speaker 3: stripping of that atmospheric blanket, the pressure dropped and the
Speaker 3: greenhouse effect failed.
Speaker 2: So the planet just got colder and colder.
Speaker 3: It led to a runaway cooling effect. The atmospheric pressure
Speaker 3: dropped below what's called the triple point of water. That's
Speaker 3: the specific temperature and pressure where liquid water can remain stable.
Speaker 3: Any liquid water that remained on the surface would have
Speaker 3: either furzen solid or it would have quickly sublimated.
Speaker 2: Meaning it went straight from a solid or liquid into.
Speaker 3: A gas, straight to gas unable to pool or flow.
Speaker 3: The atmosphere thinned and the planet was locked into a
Speaker 3: permanent deep freeze, making it physically impossible for those sixteen
Speaker 3: megasystems to flow or persist.
Speaker 2: Okay, so these two hypotheses account for the loss of
Speaker 2: surface water, but the sources also leave room for a
Speaker 2: huge portion of that water to still be around, just
Speaker 2: hidden away. Let's discuss hypothesis three, geological burial or the
Speaker 2: great hiding place.
Speaker 3: This is the domestic counterbalance, and it's a critical consideration
Speaker 3: for future exploration. Scientists hypothesize that while a portion of
Speaker 3: water was stripped away to space and a portion was
Speaker 3: frozen on the surface, a significant reserve potentially billions of
Speaker 3: cubic kilometers, migrated underground and it remains there today.
Speaker 2: So the water didn't disappear entirely, It just changed its
Speaker 2: state and location. It moved from the riverbeds down into
Speaker 2: the bedrock.
Speaker 3: Yes, modeling suggests that as the surface cooled and the
Speaker 3: atmosphere thinned, vast volumes of surface water sank into the subsurface,
Speaker 3: becoming groundwater. And because the Martian surface is now permanently frozen,
Speaker 3: there's a massive permafrost layer that extends far underground. This
Speaker 3: ancient groundwater became trapped and preserved as subsurface ice. It's
Speaker 3: protected from the solar shipping that's happening above.
Speaker 2: And this is more than just a theory. It's a
Speaker 2: critical target for finding resources. Where are scientists looking for
Speaker 2: these buried reservoirs.
Speaker 3: The evidence points primarily to two areas. Firstly, the plant
Speaker 3: and its poles hold massive ice caps, and we know
Speaker 3: from weight measurements that there are huge layers of subsurface
Speaker 3: ice extending out from those caps.
Speaker 2: Yeah. And the secondary.
Speaker 3: Secondly, significant water ice is thought to be locked into
Speaker 3: subsurface sheets across the mid latitudes, often just a few
Speaker 3: meters below the surface dust, and this provides a direct
Speaker 3: tangible link to potential future resource exploration.
Speaker 2: It's the whole field of in situ resource utilization.
Speaker 3: Exactly. If we ever want to establish a permanent human
Speaker 3: presence on Mars, we need water for life support, for
Speaker 3: growing food, for producing rocket fuel, and these buried reservoirs,
Speaker 3: which were originally fed by those sixteen megasystems, they're our
Speaker 3: best hope for finding those resources. The river's vanished, but
Speaker 3: the water they carried might just be waiting for us
Speaker 3: right below the surface.
Speaker 2: It's incredible to think that the same water that curved
Speaker 2: those canyons billions of years ago might be the water
Speaker 2: we use to sustain human life there in the future.
Speaker 3: That is the beautiful continuity of planetary geology, the history
Speaker 3: of the planet, because the key to its future the
Speaker 3: distribution of that ancient water, now stored underground, directly dictates
Speaker 3: where we might land and operate future human missions.
Speaker 2: This has been a truly monumental deep dive into ancient
Speaker 2: Martian history. We have moved so far past the abstract
Speaker 2: question of whether water existed to systematically mapping the organization
Speaker 2: and the colossal power of its hydrological past.
Speaker 3: It's a huge step.
Speaker 2: To recap the incredible scale of the new findings Mars
Speaker 2: at organized systematic river systems. We've mapped sixteen major systems
Speaker 2: that produced an estimated twenty eight thousand cubic kilometers of sediment.
Speaker 3: And that volume at single volume accounts for a staggering
Speaker 3: forty two percent of the total fluvial work done on.
Speaker 2: The entire planet.
Speaker 3: The value of this work is just immense, and this
Speaker 3: new methodology the successful combination of legacy topographical data like
Speaker 3: MLLA and contemporal high resolution imagery like CTS. Using these
Speaker 3: integrated GIS systems, it's a crucial new tool in the
Speaker 3: toolbox for planetary science.
Speaker 2: Not only four forces us to reconstruct Mars's past as
Speaker 2: a radically wetter, more dynamic world, but it also develops new,
Speaker 2: universally applicable methods for mapping ancient river basins on other
Speaker 2: potentially habitable worlds.
Speaker 3: I mean, you could apply this to icy moons in
Speaker 3: our Solar system, or even to distant exoplanets one day.
Speaker 2: It truly is a powerful picture of a completely different planet,
Speaker 2: a world of geological giants.
Speaker 3: But as always in science, especially planetary science, every answer
Speaker 3: only opens up more questions.
Speaker 2: Okay, so think back to the sheer efficiency we discussed.
Speaker 2: The researcher successfully mapped sixteen drainage systems that account for
Speaker 2: forty two percent of the global flowing sediment volume.
Speaker 3: So here's the provocative thought for you to carry forward
Speaker 3: from this. What stands out to you about the remaining
Speaker 3: fifty eight percent that's.
Speaker 2: Right, over half the work is still unaccounted for in
Speaker 2: a way, that fifty eight percent of global fluvial work
Speaker 2: was done by systems that were either too small and
Speaker 2: below that one hundred and five square kilometer baseline, which
Speaker 2: would mean they were vastly more numerous but less dominant,
Speaker 2: or and this is the really fascinating part, that fifty
Speaker 2: eight percent represents systems that are currently buried completely invisible
Speaker 2: to our current orbiters, perhaps waiting under centuries of dust
Speaker 2: or kilometers of volcanic rock.
Speaker 3: This research doesn't close the book on Mars's wet history
Speaker 3: at all. It confirms that we have mapped the main highways,
Speaker 3: but a much larger, as yet unmapped hydrological history still exists,
Speaker 3: potentially including even more ancient or protected futures.
Speaker 2: At missing fifty eight percent. That's the true frontier of
Speaker 2: Martian discovery.
Speaker 3: An organized planetary scale system that produced nearly half the erosion,
Speaker 3: and a vast unknown majority that still waits to be mapped.
Speaker 3: The deep Dive continues last characters