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the red planet, Earth's neighbor, and the destination of NASA's most ambitious mission to date. But this expedition will be harder than we ever thought possible. It hurts to think of how hard it is. It's the farthest a human being has ever been from the Earth. We got to take every precaution. As NASA's astronauts arrive at Mars, they'll face a huge obstacle. Landing on the planet is a daunting task. In the past, Mars hasn't always rolled out the welcome map. Mars is kind of like a graveyard for spacecraft. It's actually really hard to send something from Earth and land it on Mars.
This is how the European Space Agency hoped its $250 million Skiaparelli lander would touch down in 2016. But the lander systems got it wrong. The parachute detached early, sending the craft into freef fall for 33 seconds. Skiaparelli smashed into the surface at 335 m an hour, leaving a deep black scar on the Martian landscape. It turns out that Mars is actually a particularly difficult planet to land on. Even humanity's most brilliant engineers, we've got about a 50% success rate when it comes to landing on Mars.
The red planet is littered with dead spacecraft that didn't stick the landing. And for NASA's first crude descent to Mars, the space agency must learn from these mistakes. But as the crew hurdles toward the surface, they're battling the same problem as all the landers that failed before. The Martian atmosphere is 100 times thinner than Earth's, so it can't provide the drag needed to slow a spacecraft down. So, it's not like the Earth where you can have these big giant parachutes that gently glide you down to the surface. You can use some of the air, but it's hard. The red planet's thin atmosphere is a problem that's been billions of years in the making.
Mars doesn't have a large atmosphere because it's constantly being peeled away due to the lack of protection of a magnetic field. The solar wind can strip away an atmosphere. On Earth, a liquid metal core creates a magnetic field which shields the planet and helps maintain the atmosphere. Mars is different. 4.5 billion years ago, Mars and Earth formed from dust and gas in space. Mars forms where building materials were scarce. Its growth was stunted. So Mars is much smaller than the Earth.
It's a factor of 10 smaller than the Earth. And that factor of 10 in mass is important. All of that extra mass allows the inside of the Earth to stay warm and to have a core that's rotating, which generates a magnetic field. 4 billion years ago, the churning heart of Mars started to cool and solidify. And with no hot core, there's no magnetic field being generated. all of the high velocity charged particles coming from the sun pick away at the atmosphere and slowly tear it away. We know it's losing atmosphere every second uh due to the solar wind. So, you know, bye-bye atmosphere. With little Martian atmosphere to work with, NASA had to be creative to get its crewless landers to the Martian surface.
In 2012, the revolutionary Sky Crane landed the Curiosity rover using parachutes and retro rockets. Previous missions have used both a parachute and something else like a bouncy ball inflated around the spacecraft. I don't think a human crew is going to be too pleased if they're going to be bouncing onto the surface in an airbag rolling to a stop. Right. To land people on Mars, NASA will need some new tricks. The 2020 rover will overcome the challenge with the advanced supersonic parachute inflation research experiment. Aspire.
It will rapidly slow down the craft with the force of an airplane jet engine. This is fine for the rover. It's actually going to work no problem, but it's not going to work for people. A human lander will weigh far more than the 2,300lb rover. Not even supersonic parachutes could land a crew safely on Mars. NASA will need a new plan. One idea is to use the thin Martian atmosphere in a unique way. There's an idea of coming in really fast, getting to the thick part of the atmosphere, and then going horizontal to the ground and gliding and losing your momentum that
way. As the astronauts descend, they tilt the nose of the lander towards the Martian surface, aiming for the thickest part of the atmosphere close to the ground. Then they pull up at the last second using friction from the atmosphere to slow the craft. Descent engines switch on for the final touchdown. Is this a crazy idea? I mean, yeah, it's it's a little bit weird. I don't know if we'd really think about it uh doing something like this, but I mean, you've got to think outside the box sometimes. Right now, NASA's plans for landing a craft on Mars are still on the drawing board. But even if they can get astronauts onto the surface, the thin atmosphere isn't done with them yet.
It causes swirling dust storms that cover the planet's entire surface. Mars doesn't just have dust devils, it has dust hell. And these towering clouds have killed before. If NASA's astronauts arrive on Mars as planned in 2035, the settlers will find one of the red planet's biggest challenges is its dust. It's sticky. Uh, basically light from the sun can give this stuff a static charge and then it clings to stuff. So, it's not just a matter of like, you know, standing on a doormat outside your your space habitat and shaking yourself off. It's going to get in your space suit. It's going to coat your visor. It's going to cover your solar panels. If you get it in your lungs, it's not a good thing. We have to figure out how to clear this stuff out.
300 ft minus 11. Through the 60s and 70s, there you go. Apollo astronauts walked on the moon. When they returned to their landing module, they brought moon dust back with them. The lunar dust clogged seals, caused equipment to overheat, and resulted in false instrument readings. It even made the astronauts sick. You don't want to be breathing in fine dusty material um by itself. You can get things like silicosis. It's a you know almost basically a lung cancer that you can get just from breathing the dust itself. You don't want to do that.
The red planet is covered in sticky dust. And new research suggests it all came from one place, the Medusa FSY formation. When the 600-m long volcanic deposit formed 3 billion years ago, it was around half the size of the United States. But the Martian winds have eroded this structure and spread the dust across the entire planet. When the wind whips up this dust, it can have disastrous consequences. The real problem is just that all these fine particles get lofted into the atmosphere and it takes a really long time for them to settle back out. And what the dust does is it just gets up in the sky and it sits there and sits there and sits there.
As more material gets lifted into the atmosphere, it forms huge dust storms. The storms are so large they block out the sunlight and cool the Martian surface. creating a temperature difference between the ground and atmosphere that causes winds to increase and the storms to grow. October 2019, astronomers discover 20 new moons orbiting the gas giant Saturn. These tiny 3m wide objects bring the ringed planet's moon count to over 80. The most of any planet in our solar system. You hate to play favorites, but I'm going to say it. Saturn is my favorite planetary system.
It is unbelievably beautiful with this incredible system of rings and moons. And there's a lot of mystery kind of all bound up in there. The Voyager spacecraft gave us our first close look at Saturn and its rings. Two decades later, Cassini got us even closer to many of Saturn's moons. There's Prometheus, Pandora, and Atlas. Its largest moon, Titan, is a moon that's shrouded in mystery. There's Mus that's fairly small. And then Tethus and Dioni are a bit larger.
There are pair of moons, Janice and Epimetheus, that were perhaps one moon in the past. Niapotus, half of it's bright white, the other half is sort of as dark as coal, sort of ying and yang. Each of the moons of Saturn had remarkable stories to tell. In 2005, Cassini discovered that one moon's story was particularly exciting. Yeah. Enceladus. Enceladus is one of Saturn's wee little moons. It's about 300 m across. For scale, it's roughly the size of Colorado.
The spacecraft's cameras spot plumes of water vapor shooting out from Enceladus at 800 m an hour. Three times as powerful than all the hot springs in Yellowstone. The discovery of geysers gushing out of tiny little Enceladus that should have been cold and dead completely changed our view of what that moon exactly was. It's alive. That moon is alive. I'd like to be standing there on the surface of Enceladus to see with the this water vapor and ice crystals booming out of the surface at supersonic speeds.
Cassini sensors probe deep beneath the frozen surface of Enceladus, detecting hints of a rocky core. And something else even more remarkable. Underneath that thick layer of ice, there is liquid water ocean. The measurements suggest this is a huge part of Enceladus's interior volume, about 6 mi deep, because it was making Enceladus wobble in its orbit. Imagine putting liquid inside a ball and rolling it. You see the natural wobble of the ball as the liquid slloshes around. Giant liquid oceans on an alien world, opening up exciting new possibilities. Where you find water, you could possibly find life. If you would asked me 20 years ago where
there might be life in the solar system besides Earth, I think Saturn's moons would have been the last place I would have picked. But against all odds, it's looking like this tiny icy moon orbiting Saturn nearly a billion miles from the sun may be one of the best places to look for life. July 2021, a new study re-examines Cassini's plume data and finds huge quantities of methane. This large amount can't be explained by just geochemical processes. The methane might be from primordial organic matter breaking down in Enceladus's oceans. or even processes we've never seen before. But it could be that living
microorganisms help generate the methane just like they do on Earth. Enceladus might actually look a lot like early Earth in its deepest oceans when life was first arising because we know that there are some chemical pathways that are likely occurring on Enceladus that happened on Earth. These chemical pathways start with hot hydrothermal vents on Earth's cold seafloor, releasing important life-giving chemicals into the oceans. Having hydrothermal vents are a real boon to the evolution of life. These are cracks in the Earth's crust where hot material can then spew out into the ocean. And that's the energy that life needs to be able to form. And
then water. So everything is present and things are able to just grab all these resources and energy and just start to evolve. On Earth, hydrothermal vents produce methane, but only in small amounts. Microbial life living around the vents makes the rest. Maybe microorganisms do the same. at the bottom of Enceladus's deep oceans. Hydrothermal vents on Enceladus could offer the perfect location for chemistry becoming biochemistry becoming life. Hydrothermal vents normally require heat from a hot core. So, what's going on inside Enceladus?
This is an icy moon uh out there in the cold outer solar system. Where's all this heat coming from? Cassini spotted Enceladus' plumes shooting out from parallel cracks in the surface called tiger stripes. The cracks are a clue to the origin of the geysers and the energy that powers them. We look to the orbit of Enceladus itself. It's not in a perfectly circular orbit around the planet. It's on a slightly elliptical orbit. And that means that the tidal forces acting on the moon change over time. It's a little bit like the forces on a rubber ball. When the moon is closer to the planet, it's stretched out. And when the moon is farther from the planet, it's relaxed
back a little bit. So, you're going to squeeze and deform and squish the body of that moon over time, which is going to heat its interior. The warm rocky core heats up the ocean, which both powers the geysers as they burst through the surface and creates conditions that could support life. We see the energy source kicking the water out of the Enceladus subsurface. You combine that energy source and liquid water, that hearkens to putting us on the same path that early life may have taken here on the Earth. And if
that's the case, there could be little beasties swimming underneath the surface of one of Saturn's moons. Saturn's squeezing of Enceladus may have transformed it into a living world. But other moons weren't as lucky. They've been torn apart in vicious fights to the death. Since the first probe visited Mars in 1971, 16 missions have investigated the red planet from orbit. While 10 landers have explored the surface, they've revealed Mars may still be an active planet, one that once had the right conditions for life. Mars used to be thought of as this dry, aid, inhospitable environment. And thanks to the recent Mars missions, we know now that it could have sustained life.
Could there be any ancient Martian water left hidden inside the planet today? Maven investigates by analyzing Mars's atmosphere for one of water's components, hydrogen. The Maven mission is looking at hydrogen that's currently in the Mars atmosphere. This is a really important thing to study. The gas is produced when the solar wind slams into Mars's thin atmosphere and smashes apart molecules of water into hydrogen and oxygen.
Hydrogen molecules come in two forms, light regular hydrogen and the heavier dutyium. The ratio of the different types tells us about the history of water on the red planet. It turns out that it's much easier to lose the lighter version because gravity just can't hold on to something that's light as easily as a heavier thing. So, we expect that as time goes on, we'll have less and less light hydrogen and more and more heavy hydrogen. So if we can measure the outflow of hydrogen from the Martian atmosphere today and specifically whether that's light or heavy hydrogen, we can start to get some kind of idea about how much water has been lost from Mars and
therefore how much might still be there today. 2021 scientists at Caltech analyze data from Mars' rovers and orbiters to discover the ratio of dutyium to hydrogen in the atmosphere. They find less of the heavy hydrogen than expected. If Mars had lost a lot of its original water out into outer space, we'd expect to find lots of heavy hydrogen left behind in the atmosphere. But in fact, what we found was that the ratio told us that Mars didn't lose much of its water upwards and so maybe the water went downwards. Where is Mars's water hiding? Some scientists think it could be stashed away in the Martian rocks. When we look at a rock, we often think this is a really dry thing. There's no water in there. But in fact, there's
often a lot of water in rocks. And it's because it's bound up in minerals. Changes in the crust can drive these minerals to suck up huge volumes of water, equivalent to a global layer over 300 ft deep. Researchers estimate that as much as 99% of Mars's water could be locked away below the surface. And Mars hides water in other ways, too. Enter the European Space Ay's orbiter, Mars Express. Probing one mile beneath the Martian South Pole, it finds a secret store of water.
Really exciting. We've discovered a system of lakes beneath the Martian polar ice cap. Lakes of what appears to be liquid water. Now, these lakes are not very deep. They're probably only a couple of feet deep, maybe in some places even a couple of inches deep. But they're quite large. Some of these are about 20 m across. And there's even some suggestion that these are connected with channels, kind of a system of very shallow great lakes near the south pole of Mars.
The Martian poles are the coldest regions on the planet. Temperatures can reach 200° below zero. So why is it that underneath this cold ice you might even find liquid water? Well, remember you're actually going down closer into the interior of Mars there. And so that's warm. It's possible that the geological activity inside Mars is warming the ice from the underneath. But heat from the interior of Mars wouldn't be enough to keep these lakes liquid. The secret ingredient may be salt. If you've ever spread salts on an icy driveway, you'll notice that where the salt hits the driveway, the ice begins to melt. Salt water actually freezes at
a much lower temperature than water that's fresh. So if it's salty water, it could actually stay liquid at lower temperatures. We still aren't 100% sure that the lakes are completely liquid. Some scientists think they could be lakes of frozen clay. Until we have a rover that can explore beneath the poles, we won't know for sure. The only real way we can tell for sure is to send some kind of mission that drills right down through that polar ice and samples what we find at the bottom.
Wherever it may be hiding, Mars's water is locked away. But in its past, the planet had impressive lakes and rivers. Did they ever host life? To find out, the rovers take a deep dive into Mars. Veteran crew member Curiosity explores the Gale Crater. The rover's mission to find evidence of whether Mars could have supported life. Los Alamos National Laboratory. Principal investigator of Curiosity's chem Cam, Nina Lanza works closely with the rover patrolling Mars 34 million miles away. In many ways, Curiosity is like my first child. We had to take such good care of
her while she was still here on Earth. But like all children, she had to forge her own path. And so we had to send her on her way to discover new things on Mars by herself. Chemcam uses a precision laser that analyzes the chemical composition of Martian rocks. We have a laser that we focus onto a target up to 23 ft away and we vaporize a little material and then we look at the light made by this vaporized material and figure out what elements are in the rock. Working with an instrument like ChemCam is really a childhood dream come true because I was always hoping to work on a spaceship. And today I work on a spaceship with lasers. How cool is that?
With their long-distance teamwork, Nina and Curiosity discover rocks with a shiny coating laced with manganese. One of the most exciting discoveries from Curiosity in Gail Crater was the existence of high concentrations of an element called manganesees. And that's because manganesees on Earth is very closely tied to life. Could the manganesees of Mars be linked to life forms? To investigate, scientists look at similar coatings called varnish on desert rocks here on Earth. So, I have an example here of some rock varnish, and you can see it's actually incredibly dark. It has a lot of iron oxide, manganese oxide, and clay minerals in them. And the rocks can sometimes
have none of these things in the rock itself. So, the question is, where does this coating come from? Often we find microbes associated with the varnishes. And so, possibly these microbes actually help fix the manganesees onto the surface. The age of these Earth varnishes may provide a clue to Mars' distant past. Here, they only appear after a significant event in our history, the creation of the oxygen we breathe. 4.5 billion years ago, an asteroid the size of Pluto slammed into the surface of infant Mars. It melted the surface of the planet. It blew the atmosphere into space and it boiled away the oceans. If life had gotten a foothold on the
planet, that life would have been completely exterminated. But some scientists believe this extinction could have been brief and that life could have started again from scratch. One of the wonderful things to imagine is that there probably wasn't a single origin of life. It's not like it happened once and then everything just went from there. Maybe there were multiple times that life got started and went extinct. 10 million years after the Borealis impact crushed the planet's northern hemisphere, Mars is cooled enough for its surface to become solid once more.
The planet has some of the ingredients for life. The right molecules, a stable surface, and an energy source. But something's missing. 4.49 billion years ago, the surface of Mars is dry. And without water, life can't start over. And a second generation of Martian can never arise. As far as we know life, water is absolutely fundamentally important to life. 2004, NASA's Opportunity Rover lands on Mars. Part of its mission is to search for evidence that water returned to Mars after the Borealis impact.
It's not long before Opportunity stumbles across something strange on the surface of a fossilized sand dune. Bizarre round metallic rocks. These rocks are called blueberries, and they're an important find for planetary geologists like Janie Rataba because fossilized sand dunes also exist on Earth. And Utah's petrified dunes are also littered with blueberries. This is really exciting because we've seen the exact same thing on Mars. Finding blueberries on Mars is significant because the Borealis impact melted the planet. So, anything found on Mars today must have formed after the
impact. But crucially, these nodules of iron oxide form deep underground and in the presence of water. In order to form one of these little blueberries, there needs to be huge amounts of water flushing down through the fossil sand dunes. And as it does that, it carries with it all of the iron oxides around each sand grain. And just one tiny little one like this. Now, this is maybe about an ounce of iron, maybe a little bit more. And in order to get an ounce of iron to concentrate into this blueberry, you need to have a thousand gallons of water. Blueberries form deep inside sandstone. But over thousands of years, wind erosion blows away the softer rock, leaving just the blueberries behind.
So, if we walk to the edge of this pile of blueberries, we can see the process by which they're actually eroding out of the rock. The blueberries right here are contained within this fossil sandstone layer. The winds are blowing in this direction down the layers and they're they're actually eroding out the soft sandstones right here and leaving behind the very dense iron nodules. And as they pluck themselves out of the rock, they roll down the hill and then collect right here in between layers. We know we've found conditions just like this on Mars. We have fossil sand dune layers. We also have blueberries all over the surface. So, we know the same kinds of things had to have happened on
Mars that have happened here. There has to be water flowing through the rock gathering iron. And then there has to be a huge amount of wind to strip away the fossil sand dunes. For blueberries to exist on the surface of Mars today, the red planet must have gotten its water and its atmosphere back after the catastrophic impact. With liquid water on the surface, the ingredients of life might have combined once again to create a second generation of Martians. But where did this water come from? The answer is surprising. It could have been in the planet itself. Water is incredibly abundant. Uh we know that there's water deep in the uh earth's mantle. And uh so it's entirely possible that on Mars, there was water so deep in the planet that
even after this catastrophe, it came back up. On the Earth, scientists have used the seismic waves of earthquakes to detect an oceans's worth of water chemically embedded in minerals deep underground. A similar water source could have been hidden hundreds of miles below post impact Mars. And volcanoes could have brought that water back to the surface. One way for water to get from deep underneath the surface to the surface of the planet would be through geological activities. Volcanoes, for example. We know that volcanoes spew out a lot of gases on Earth, including water vapor. A
and we see volcanoes on Mars. Mars is home to the largest volcanoes in the solar system. The biggest of all, Olympus Mons is over three times taller than Mount Everest. 4.49 billion years ago, volcanoes spew lava spiked with water into the atmosphere and create ferocious rainstorms that flood the surface of Mars. Over tens of thousands of years, Mars becomes a watery world once again with the perfect conditions for a second generation of Martians to rise up.
It would seem that when you have a massive collision like what happened to Mars, it would be game over for life. But there's something more complicating going on. Maybe that asteroid impact kicked off an entirely new cycle of life on Mars. In theory, 4 billion years ago, a second generation of single cellled bacterial life arose on Mars. And for the very first time, there was life on two planets in the solar system. 140 million miles away, life on Earth had just begun. And thanks to Earth's stable climate, it would one day evolve into us. But the outlook for Mars was very different. Evidence from the Mars Reconnaissance Orbiter suggests an icy
apocalypse was about to strike. For Mars's second generation, winter was coming. 4 billion years ago, the first life has arisen on Earth. But on Mars, life may be starting out for a second time. It's possible that Mars had life before Earth did. It got wiped out and then got started again by rehydrating the planet. A planetary collision is blown away Mars' atmosphere and oceans along with any life. But giant volcanoes have brought water back to the surface from deep within the planet. This could have allowed for a second generation of life
to rise up. But these Martians are about to be tested to their limits by catastrophic climate change. 2008 NASA's Mars Reconnaissance Orbiter flies high over the surface of Mars. Its ground penetrating instruments peer deep below the surface, aiming to unlock Mars' geological secrets. As it scans near Mars's equator, the orbiter spots something that has no right to be there. A vast underground glacier 1 mile thick and three times the size of Los Angeles. Ice on this scale should only form at the frigid poles. The only explanation, Mars must have been tipped over with its equator tilted away from the sun. The tilt on Mars's
axis has actually changed significantly over time and in nonsistatic ways. It just happens randomly that it will start moving. And so there are some models that suggest that Mars has actually been almost tipped over on its end. Most planets wobble and from time to time they wobble so much they can tip over leading to super winters. If that happened here on Earth, Los Angeles could become the Arctic. Well, you can imagine something similar would happen on Mars. How drastic the change would be. You're used to seeing the sun overhead. It's very warm. There's probably liquid water. And as the planet starts going this way, the sun is not going to rise as high in the sky. Eventually, you may not see sunrise for half a year. And any
water that's there is going to be frozen solid. 3.9 billion years ago, Mars is tilting by as much as 80°. Winter temperatures drop below minus 125° F. As the polar ice sheet spreads quickly toward the equator, liquid water is frozen solid along with any potential Martians. The water that drives the biochemistry of life freezes inside the tiny bacteria. Ice crystals form and puncture the Martian cell walls until eventually they die. Every 120,000 years, the tilt of Mars changes as again and again, the planet's chaotic wobble flips the Martians in and out of the deep freeze.
Any second generation of life on Mars is left in tatters. In 2016, astronomers release astonishing evidence of a missing ninth planet on the frozen edges of our solar system, 100 billion miles from the sun. Until our telescopes find it, we can only guess what this mysterious planet 9 is like. But the first option is perhaps the most surprising. Planet 9 could be made from rock, just like the Earth, but 10 times more massive. A so-called rocky super Earth. When we looked out into the universe, we realized that the most common type of planet in the entire galaxy is something
we don't have, something called a super Earth. The Kepler Space Telescope finds alien worlds by measuring the tiny dip in light as a planet passes in front of its host star. Most of the alien solar systems Kepler finds have super Earths. So, how come our star doesn't have one? Could it be possible that planet 9 is our missing super Earth? If planet 9 is a rocky super Earth, what will it look like up close? Planetary geologist Janie Ratab imagines Planet 9 as a dramatic world of fire and ice. Right now, we're in Iceland. We're flying over amazing, beautiful volcanic landscapes of Iceland. We think this might be the perfect landscape for
thinking about what might be happening on planet 9 if it's a rocky super Earth. These black mountains and lava flows were created by leftover heat from the Earth's formation spilling out onto the surface. Planet 9, born with so much more insulating rock, should have even more of this leftover heat trapped inside it. What we're talking about is a body that's maybe 10 times the mass of the Earth. I'd expect because it's so large that we should have lots more internal heat. And so even though it's far away in the solar system, it's far away from the sun, it's still got lots of its own energy.
Touching down on the surface of Planet 9, you'd find a world as inhospitable as you could imagine. Billions of miles from the sun, the surface is lit by little more than the twinkle of distant stars and the red glow of intense geological activity on the surface. We can imagine if we were on a super rocky Earth, planet 9, we could have a landscape just like this one. There should be volcanoes erupting all the time. And the other thing we should see is lots and lots of ice and snow blanketing the landscape. This is because the atmosphere is so cold that parts of it have condensed and settled back down onto the surface.
You're going to have volcanoes. You're going to have canyons. You're going to have plate tectonics, mountain building. All of these processes are still going to be going on out there in what we normally would think of as the frozen cold and dead world of the outer solar system. As hot lava reaches the surface, it freezes suddenly in the cold of space, perhaps forming a weird volcanic glass called obsidian. Another feature shared with the sub-zero volcanoes of Iceland. Okay, let's put this whole thing together. We have a landscape that's kind of dimly lit by starlight, but maybe also by the reddish glow from erupting lavas spreading across the
landscape. And then behind you, you have gases that are changing immediately to snow and falling as snow down to the surface and it would just be a beautiful magical landscape. The case for a giant rocky planet 9 is compelling because it paints such a vivid picture of a living volcanic world. But there's a problem. If planet 9 is in fact a super Earth, how did it form and where did it form? We don't have any other super Earths in our solar system and the ones we see around other stars are typically really close to their star. So, how did our super Earth end up way out there at the edges of our solar system? For planet 9 to be our rocky super
Earth, it would have had to have formed in the inner solar system and then migrated out to its current position. And that's a problem because there probably wasn't enough rocky material left over in the early solar system to create both the massive planet 9 as well as Mercury, Venus, Earth, and Mars. It's really hard to imagine that we could have formed a 10ear Earth mass planet here and still formed the rocky planets that we see today. Time for a new theory. What if planet 9 formed from ice in the outer solar system? Calculations tell us it would have to be 10 times the mass of the Earth. And here's the kicker.
An ice world that big would have an internal ocean of liquid water. A new world is revealed where icy geysers shoot through cracks in the frozen crust. And deep below it lies the largest body of liquid water in the solar system. The planets that make up our solar system seem to follow a pattern. The four closest to the sun are all made from rock. The next four are giants made mostly from gas. Beyond Neptune, gas is replaced by multiple worlds made from ice. This is the Kyper belt, a frozen realm of water ice asteroids, millions of them.
The Kyper belt is a region of space outside of Neptune's orbit that extends out about 50 times the distance from the Earth to the Sun. So, it's really far out there. And this is populated by icy bodies. These are giant chunks of ice that have some rock and other things in them, but they're mostly ice. Perhaps planet 9 is made from the same materials. An overgrown version of the Kyper belts most infamous citizen, Pluto. Poor Pluto. Discovered in 1930 by Clyde Tombow, this tiny ice world smaller than our moon was quickly proclaimed the ninth planet. But in the 1990s, Mike Brown and others discovered a host of icy worlds orbiting out with Pluto. Pluto was just another
Kyper belt object and got demoted to dwarf planet to the dismay of much of the world. Everybody loves the idea that uh that I killed Pluto and now I'm trying to atone for my sins by replacing it with a new ninth planet. In fact, even my daughter suggested this long before we started looking for planet 9. Uh she said, "You know, you should find a new planet and then you can have found a planet and there'll be nine planets again and everybody will like you again." If planet 9 is an icy Kyper belt world, it'll be the biggest we've ever found. Pluto, the biggest object we know out there in the Kyper belt now, is less than 1% the mass of the Earth. less than that. Planet 9, we think, is 10 times the mass of the Earth. So, we're dealing
with a factor of thousands of times in mass between the largest belt object that we know now and the size of planet 9. Imagine Saturn without its rings, just a pale globe floating in the darkness of space. Undoubtedly, the one thing that captures everyone about Saturn is the rings. It's inspired fiction stories, and it's inspired everyone who's looked at it in the night sky. When I was four or 5 years old, my parents bought a small department store telescope. And I remember looking down into that eyepiece and seeing this perfect jewel of a planet. There's just nothing better than this. And you can just see the rings going around the planet just perfectly.
They're just a gorgeous elliptical racetrack. From the eyepiece of a small telescope, the rings seem quiet and serene. But up close, it's a very different picture. We know this thanks to a space probe called Cassini and over 10 years of images like these. Ice particles jostle for position like stock cars traveling inside the rings at hundreds of thousands of miles an hour. These particles range in size from chunks of ice as big as houses to the finest powder snow. It wasn't until we went to Saturn and stayed there with Cassini that we learned just how fiercely complex it is. You have the gravity of the planet itself and all of
these moons interacting with the rings and the moons and the planet. All of these things are sculpting that entire system on scales that are both subtle and gross and it makes this magnificent crown jewel of the solar system. As small moons go around inside, the ring particles dance around them in response. We see areas of the rings that get raised up as a moon goes by. Moons will even switch orbits with each other. So, there's a lot of dynamic stuff going on inside the rings. Scientists believe that from time to time, Saturn's icy moons break up, adding new material to the rings. This means that the structure of the rings is constantly evolving. With Cassini, scientists can deconstruct the physics of this evolution, and it's
teaching us the rules that make the whole universe tick. All the planets in our solar system evolved from the same flat disc of dust and gas 4 and 1/2 billion years ago. Astronomers see similar discs around young distant stars. But even with our most powerful telescopes, we can't see planets forming. They're too far away. But Saturn's rings are right on our doorstep. a veritable snapshot of a mini solar system caught in the process of formation. Looking at the rings, we're looking at the formation of planets or bodies in an arrested state of development. It's like you took the beginning stages of the formation of the planets but stopped it.
Cassini shows structures forming spontaneously inside the rings. They don't even need to be tickled. They don't need to be disturbed into forming structures. They form them on their own. Does this tiny moon captured in the process of formation show us how the Earth started its life? You get something that just happens to form out of random processes. And that mimics what astronomers think they're seeing in protolanetary discs surrounding other stars in the cosmos around us. Cassini sees curious propeller-like structures inside Saturn's broad A- ring. They're caused by ring particles washing over tiny hidden moons.
The particles collide with the moons, sending them into random, everchanging orbits, sometimes closer to Saturn and sometimes farther away. Perhaps similar forces influence the Earth's formation around the Sun, pushing it into closer or wider orbits. Saturn's rings also help us understand why planets stop growing. A walnut-shaped moon called Pan sits near the middle of Saturn's A- ring with so much ice around it to gobble up. Japan should be huge, but it's tiny, only 20 m in diameter. If you have a moon embedded in a disc of ring particles, you might naively think
it just secretes ring particles until it grows into a, you know, a bigger moon. But actually, we find moons create gaps in the ring around them. So, pan has created the inky gap. Daphnness has created the killer gap. Rather than pulling ring material in, Pan appears to push it away. As the moon passes the slower moving material outside it, Pan's gravity flings the particles out into wider orbits. The faster material inside Pan's orbit is slowed as it passes the little moon, causing it to fall away towards Saturn. This natural cut off and growth might explain why multiple planets form around stars instead of single giant planets
that eat the whole buffet. Of all Cassini's discoveries, the most important is also the most surprising. A tiny ice moon that may be home to life. For most of history, the only moon we've been able to study up close is our own. Multiple deep craters tell a powerful story. Our moon is dead. There's no active geology or weather to wipe away these ancient scars. But what about the moons around other planets like Saturn? Are they dead, too? Our first assumption about Saturn was that the moons would be like that, cold, dead, lifeless relics from the early solar system.
It wasn't until we invented spacecraft that could go to these moons that we discovered how incredibly diverse our solar system truly is. Take Enceladus, an ice moon barely 300 m across. Nobody paid it any attention a decade ago, but today it's a geological rock star. And this is why. Enceladus orbits inside Saturn's outermost ring, the E-ring. The E-ring puzzled scientists because they couldn't figure out how a ring so broad and so diffuse could hold itself together.
The Cassini team decided to take a close flyby of Enceladus to solve the mystery. Did it have something to do with keeping the particles together? What was the connection between the E-ring and Enceladus? Well, now we know that Enceladus is actually responsible for the E-ring being there in the first place. 2005, Cassini captures an astonishing sight. A 100 geysers shooting ice particles miles into space from cracks in the South Pole. Enceladus is hurling its guts into space at a colossal rate. As Enceladus orbits Saturn, these icy plumes feed a vast shimmering halo around the planet, the mysterious E-ring.
This icy plume also interacts with Saturn's magnetic field, causing a plasma cloud of charged particles. The particles race along Saturn's magnetic field lines and slam into Saturn's polar atmosphere, raising huge ultraviolet auroras. Geysers explain the e-rain. But how can they exist on a frozen moon a billion miles from the sun? On Earth, geysers form in highly volcanic places where water comes into contact with hot rocks. Enceladus, so small and so far from the sun, should be cold and dead. But thanks to Saturn's gravity, it's not. The source of the heating on Enceladus is the eccentric orbit of that moon.
Sometimes it's a little closer to Saturn, sometimes it's a little further away. And that heating on Enceladus from that kneading gravitationally making the moon stretch and pull is what warms the interior causing the activity on Enceladus that we see today. The gravitational pull of Saturn reaches deep into Enceladus beyond its water ice exterior, gripping its rocky core. As Saturn's grasp strengthens and weakens, it massages this cold, rocky heart, bringing it to geological life with frictional heat. The heat melts the ice around it, creating a vast subsurface lake at the southern pole of Enceladus. This water jets out through huge cracks in the surface ice. On Earth, where there's liquid water, there's life. Could Enceladus have what
it takes for simple organisms to exist? Once Cassini saw these geysers, the scientists knew they had found something extremely wonderful. They actually changed the mission of Cassini itself, changed its trajectory. We sent the Cassini spacecraft to fly very, very close over these cracks where the water was rushing out. Scientists clung to the faint hope that the water would contain salts and organic molecules like ammonia, the building blocks of life here on Earth. Stunningly, Cassini sensors tasted all of them in abundance. In that plume there's organic material. It's not water. It's a soup. That's incredible. All the main requirements for habitability, energy source, liquid water, a source of biological nitrogen
and ammonia, organic material, and the samples are coming up into space. There's a big sign. Free samples. Take one. There could be life that could have evolved there. Now, we don't know. We haven't seen it. But the conditions there are as good there now as they were on Earth three billion years ago when life arose here. The sensational realization that Enceladus may harbor life has sparked intense debate about future missions to find it because it has a rival for those precious research dollars. Saturn's largest moon, Titan, could also be home to life. Bizarre life. And we may have already found it.
