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SUB BY : DENI AUROR@
https://aurorarental.blogspot.com/
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3.7 billion years ago,
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early life was on the brink of extinction.
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Colossal impacts...
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Ferocious climate change...
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And total atmospheric collapse have turned paradise into hell.
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But this isn't earth ...
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it's Mars ...
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and this is the violent history of perhaps
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the first life forms in our solar system.
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Could these martians still exist today?
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Could they even be living among us?
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Captions paid for by discovery communications
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Scientists suspect that life may once have thrived on Mars...
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That the barren world we see today
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swarmed with martians long ago.
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If I had to bet something incredibly valuable to me ...
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if I had to bet my car ... on whether or not
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there's life on Mars,
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or evidence of past life on Mars,
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I'd take that bet.
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The building blocks for life
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are widespread in the universe,
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and early Mars could have been the perfect place
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to pull these ingredients together.
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If you had a recipe book for everything you need for life,
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you'd have things like water, organic chemistry,
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a stable surface, a thick atmosphere ...
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well, Mars had all of those.
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Mars satisfies every specific requirement
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for letting life get started.
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Life on Mars
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may have been inevitable,
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and we've sent a robot army to hunt for signs of it.
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But so far, it's been elusive.
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Our rovers, landers, and satellites
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haven't found life yet,
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but they have found evidence of something extraordinary.
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Mars was the victim of a devastating series
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of extinction-level events
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that rocked the red planet to its core...
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Leading us to wonder,
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if life could have started over multiple times,
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with generation after generation of martians
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rising and falling through Mars' violent history.
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It seems likely that a first Genesis of life
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could have occurred very early on in Mars' history,
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just as soon as the crust was cool enough
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to give it a solid foothold.
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The secret to this early life would have been
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a crucial ingredient, one shared by the young earth.
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Dry, harsh Mars once had oceans.
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For life to get started,
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you need some carbon, an energy source,
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it needs nutrients like nitrogen...
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But those are likely to be present on Mars,
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they are present and widespread on earth.
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The essential requirement is really the liquid water.
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Picture Mars
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4.5 billion years ago.
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Molten rock has cooled to form a solid crust.
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Water collects on the surface, forming primitive oceans.
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Rain clouds sweep across
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the steaming, volcanic landscape,
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and in shallow pools of water,
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the martians begin to emerge.
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But these first aliens are simpler
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than Sci-Fi would have us believe.
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We're probably not talking about little green men
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or women, or whoever.
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Walking around on the surface of Mars, we ...
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we're talking about something probably
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much, much smaller and simpler,
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single-celled life.
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If would look familiar,
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it would look just like bacteria on earth.
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Little, tiny, round, rod-shaped organisms.
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If this generation
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of bacterial martian life really did exist,
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it was the first life to grace our solar system.
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Multiplying inside the rock pools of Mars
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long before life took hold on earth,
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Mars' small size would've given it a head start.
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Because Mars is smaller
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than the earth it would have cooled
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a little bit faster than we did.
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So early on in the life of the solar system,
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Mars may have been more like earth
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than earth was at the time.
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Let's go back 100 million years
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after the sun formed.
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The surface of the earth is still a molten lake.
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But martian life could be thriving
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on the smaller, cooler world.
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But these first martians won't have long
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to enjoy their time in the sun.
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Inescapable death is already on its way from space...
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A cosmic bomb so huge,
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it would completely alter the shape of the planet,
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leaving it lopsided,
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the northern hemisphere crushed.
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Most planets are round,
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and that's just something you don't really
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give much thought to,
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but it turns out Mars isn't as round as it could be.
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The Southern hemisphere, on average,
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has a higher elevation than the northern hemisphere.
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So, in other words, if you were to start on the north pole
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and walk all the way around to the south pole,
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you'd be walking uphill, essentially, the whole time.
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So, we call this difference between the northern
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and the Southern hemisphere,
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we call this the crustal dichotomy on Mars,
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and it's been one of the biggest mysteries of the planet,
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you know, it's the first thing that you see about it,
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and you say, well, how could this possibly have happened?
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In 2008, scientists mapping
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the surface of Mars came up with an explanation
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for the massive dent in the planet, shown in blue.
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This basin, the biggest in the solar system,
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had to be the result of a massive impact.
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Called the borealis impact,
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it blasted out a crater 6500 miles wide and five miles deep,
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big enough to swallow the entire United States
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with room to spare.
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Something really big happened.
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In fact, the entire top half of the planet
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seems to have practically been blown off.
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The only thing that could do that is a huge collision,
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and we're talking a collision
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with something the size of pluto, perhaps.
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You're talking about an impact
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that makes the dinosaur killer impact
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65 million years ago look pretty much like a wet firecracker.
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4.5 billion years ago,
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the early solar system is filled
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with planetesimals and protoplanets ...
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asteroid-like leftovers from a planet building process
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that created Mars and the earth.
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One of these asteroids is huge,
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and it's on a direct collision course with Mars.
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Any microscopic martians have just seconds to live.
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If this impact was happening today
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and we were so unlucky as to be there to witness it,
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what you first would have seen is another moon in the sky...
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And then you would've looked back and seen,
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oh, it's getting bigger.
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As it came down it would have filled the entire sky,
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from horizon to horizon,
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and as it struck,
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the top would have still been well out into space.
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The impactor
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is 1200 miles across,
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the size of pluto,
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and as it hits, the energy of the impact
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shakes Mars to its core.
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The entire planet wobbles like jell-o.
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As it came down,
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it would have been hitting into the surface of Mars
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as fast as a bullet out of a gun,
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and it would have slammed into the surface
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and sent a shockwave out
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that would've been bigger than any earthquake ever recorded.
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It would have been like a Tsunami of rock
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coming out and tossing us out of the way.
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The impact is catastrophic.
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It blows nearly half the planet's surface into space
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and turns what crust remains into a boiling lake of lava.
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You can't have an impact of that scale
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without almost melting the planet.
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It's not literally a planet breaking event,
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but it's a planet melting event,
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and it is, it is the sterilization
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of the planet at that point.
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The surface of Mars was molten,
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its atmosphere blown into space,
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the oceans boiled away.
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If Mars was home to the first generation of life
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in our solar system,
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that life didn't stand a chance.
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It would take the surface of Mars 50 million years
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to recover from the impact.
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But what sort of planet will rise from the ashes?
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Compelling new evidence suggests that the conditions for life
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may have returned to Mars,
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but did life itself make a comeback?
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This impact was only a blip in time,
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and there was possibilities for life
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and the planet to recover.
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4.5 billion years ago
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an asteroid the size of pluto
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slammed into the surface of infant Mars.
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It melted the surface of the planet,
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it blew the atmosphere into space,
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and it boiled away the oceans.
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If life had gotten a foothold on the planet,
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that life would have been completely exterminated.
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But some scientists believe this extinction
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could have been brief,
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and that life could have started again from scratch.
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One of the wonderful things
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to imagine is that there probably wasn't
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a single origin of life.
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It's not like it happened once
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and then everything just went from there.
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Maybe there were multiple times that life got started
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and went extinct.
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Ten million years
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after the borealis impact
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crushed the planet's northern hemisphere,
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Mars has cooled enough for its surface
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to become solid once more.
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The planet has some of the ingredients for life ...
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the right molecules, a stable surface,
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and an energy source.
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But something's missing.
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4.49 billion years ago the surface of Mars was dry,
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and without water, life can't start over
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and a second generation of martian can never arise.
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As far as we know life,
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water is absolutely, fundamentally important to life.
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2004 ... NASA's opportunity rover
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lands on Mars.
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Part of its mission is to search for evidence
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that water returned to Mars after the borealis impact.
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It's not long before opportunity
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stumbles across something strange on the surface
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of a fossilized sand dune...
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Bizarre, round, metallic rocks.
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These rocks are called blueberries,
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and they're an important find for planetary geologists,
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like jani radebaugh,
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because fossilized sand dunes also exist on earth.
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And Utah's petrified dunes
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are also littered with blueberries.
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This is really exciting
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because we've seen the exact same thing on Mars.
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Finding blueberries on Mars
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is significant, because the borealis impact
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melted the planet,
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so anything found on Mars today
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must have formed after the impact.
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But crucially, these nodules of iron oxide
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formed deep underground and in the presence of water.
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In order to form one of these little blueberries,
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there needs to be huge amounts of water
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flushing down through the fossil sand dunes,
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and as it does that,
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it carries with it all of the iron oxides
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around each sand grain.
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And just one tiny, little one like this ...
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now, this is maybe about
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an ounce of iron, maybe a little bit more ...
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and in order to get an ounce of iron
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to concentrate into this blueberry,
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you need to have a thousand gallons of water.
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Blueberries form
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deep inside sandstone.
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But over thousands of years,
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wind erosion blows away the softer rock,
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leaving just the blueberries behind.
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If we walk to the edge of this
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pile of blueberries,
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we could see the process by which
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they're actually eroding out of the rock.
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The blueberries right here contain
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within this fossil sandstone layer.
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The winds are blowing in this direction,
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down the layers,
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00:13:33,479 --> 00:13:36,547
and they're actually eroding out the soft sandstones right here
270
00:13:36,549 --> 00:13:40,618
and leaving behind very dense iron nodules,
271
00:13:40,620 --> 00:13:42,086
and as they pluck themselves out of the rock,
272
00:13:42,088 --> 00:13:44,655
they roll down the hill and they collect...
273
00:13:44,657 --> 00:13:48,659
Right here, in between layers.
274
00:13:48,661 --> 00:13:50,862
We know we found conditions just like this on Mars.
275
00:13:50,864 --> 00:13:52,930
We have fossil sand dune layers,
276
00:13:52,932 --> 00:13:56,266
we also have blueberries all over the surface,
277
00:13:56,268 --> 00:13:57,802
so we know the same kinds of things
278
00:13:57,804 --> 00:14:00,204
had to have happened on Mars that have happened here.
279
00:14:00,206 --> 00:14:02,140
There has to be water flowing through the rock,
280
00:14:02,142 --> 00:14:03,407
gathering iron,
281
00:14:03,409 --> 00:14:05,643
and then there has to be a huge amount of wind
282
00:14:05,645 --> 00:14:10,047
to strip away the fossil sand dunes.
283
00:14:10,049 --> 00:14:11,115
For blueberries to exist
284
00:14:11,117 --> 00:14:13,851
on the surface of Mars today,
285
00:14:13,853 --> 00:14:15,786
the red planet must have gotten its water
286
00:14:15,788 --> 00:14:20,825
and its atmosphere back after the catastrophic impact.
287
00:14:20,827 --> 00:14:22,460
With liquid water on the surface,
288
00:14:22,462 --> 00:14:25,630
the ingredients of life might have combined, once again,
289
00:14:25,632 --> 00:14:30,434
to create a second generation of martians.
290
00:14:30,436 --> 00:14:33,371
But where did this water come from?
291
00:14:33,373 --> 00:14:36,307
The answer is surprising.
292
00:14:36,309 --> 00:14:38,610
It could have been in the planet itself ...
293
00:14:38,612 --> 00:14:40,210
water is incredibly abundant.
294
00:14:40,212 --> 00:14:42,013
We know that there's water deep,
295
00:14:42,015 --> 00:14:44,515
deep, deep in the earth's mantle,
296
00:14:44,517 --> 00:14:47,218
and so it's entirely possible that on Mars
297
00:14:47,220 --> 00:14:48,853
there was water so deep in the planet
298
00:14:48,855 --> 00:14:53,457
that even after this catastrophe, it came back up.
299
00:14:53,459 --> 00:14:54,692
On the earth, scientists
300
00:14:54,694 --> 00:14:57,628
diffuse the seismic waves of earthquakes
301
00:14:57,630 --> 00:15:00,231
to detect an ocean's worth of water
302
00:15:00,233 --> 00:15:04,335
chemically embedded in minerals deep underground.
303
00:15:04,337 --> 00:15:06,537
A similar water source could have been hidden
304
00:15:06,539 --> 00:15:10,441
hundreds of miles below post-impact Mars,
305
00:15:10,443 --> 00:15:15,212
and volcanoes could have brought that water back to the surface.
306
00:15:15,214 --> 00:15:16,780
One way for water to get from
307
00:15:16,782 --> 00:15:19,516
deep underneath the surface to the surface of the planet
308
00:15:19,518 --> 00:15:21,585
would be through geologic activities ...
309
00:15:21,587 --> 00:15:23,220
volcanoes, for example.
310
00:15:23,222 --> 00:15:25,823
We know that volcanoes spew out a lot of gasses on earth,
311
00:15:25,825 --> 00:15:27,191
including water vapor,
312
00:15:27,193 --> 00:15:29,660
and we see volcanoes on Mars.
313
00:15:32,965 --> 00:15:34,332
Mars is home to the largest
314
00:15:34,334 --> 00:15:36,834
volcanoes in the solar system.
315
00:15:36,836 --> 00:15:39,203
The biggest of all, Olympus mons,
316
00:15:39,205 --> 00:15:42,340
is over three times taller than mount Everest.
317
00:15:45,177 --> 00:15:50,448
4.49 billion years ago volcanoes spew lava spiked with water
318
00:15:50,450 --> 00:15:54,085
into the atmosphere and create ferocious rainstorms
319
00:15:54,087 --> 00:15:57,588
that flood the surface of Mars.
320
00:16:04,129 --> 00:16:06,197
Over tens of thousands of years
321
00:16:06,199 --> 00:16:09,434
Mars becomes a watery world once again
322
00:16:09,436 --> 00:16:12,303
with the perfect conditions for a second generation
323
00:16:12,305 --> 00:16:16,207
of martians to rise up.
324
00:16:16,209 --> 00:16:17,274
It would seem that
325
00:16:17,276 --> 00:16:19,009
when you have a massive collision,
326
00:16:19,011 --> 00:16:20,211
like what happened to Mars,
327
00:16:20,213 --> 00:16:22,213
it would be game over for life.
328
00:16:22,215 --> 00:16:24,782
But there's something more complicated going on.
329
00:16:24,784 --> 00:16:26,417
Maybe that asteroid impact kicked off
330
00:16:26,419 --> 00:16:30,722
an entirely new cycle of life on Mars.
331
00:16:30,724 --> 00:16:31,856
In theory,
332
00:16:31,858 --> 00:16:33,524
four billion years ago,
333
00:16:33,526 --> 00:16:36,627
a second generation of single-cell bacterial life
334
00:16:36,629 --> 00:16:38,863
arose on Mars,
335
00:16:38,865 --> 00:16:41,265
and for the very first time there was life
336
00:16:41,267 --> 00:16:45,036
on two planets in the solar system.
337
00:16:45,038 --> 00:16:50,008
140 million miles away, life on earth had just begun,
338
00:16:50,010 --> 00:16:52,343
and thanks to earth's stable climate,
339
00:16:52,345 --> 00:16:55,946
it would one day evolve into us.
340
00:16:59,084 --> 00:17:02,387
But the outlook for Mars was very different.
341
00:17:02,389 --> 00:17:04,989
Evidence from the Mars reconnaissance orbiter
342
00:17:04,991 --> 00:17:10,461
suggests an icy apocalypse was about to strike.
343
00:17:10,463 --> 00:17:15,400
For Mars' second generation, winter was coming.
344
00:17:40,259 --> 00:17:41,459
Four billion years ago,
345
00:17:41,461 --> 00:17:44,261
the first life has arisen on earth,
346
00:17:44,263 --> 00:17:49,967
but on Mars, life may be starting out for a second time.
347
00:17:49,969 --> 00:17:51,102
It's possible that Mars
348
00:17:51,104 --> 00:17:53,804
had life before earth did ... it got wiped out ...
349
00:17:53,806 --> 00:17:59,877
and then got started again by rehydrating the planet.
350
00:17:59,879 --> 00:18:01,278
A planetary collision
351
00:18:01,280 --> 00:18:04,148
has blown away Mars' atmosphere and oceans,
352
00:18:04,150 --> 00:18:06,284
along with any life,
353
00:18:06,286 --> 00:18:09,754
but giant volcanoes have brought water back to the surface
354
00:18:09,756 --> 00:18:11,756
from deep within the planet.
355
00:18:11,758 --> 00:18:12,957
This could have allowed
356
00:18:12,959 --> 00:18:15,893
for a second generation of life to rise up.
357
00:18:15,895 --> 00:18:18,996
But these martians are about to be tested to their limits
358
00:18:18,998 --> 00:18:22,199
by catastrophic climate change.
359
00:18:30,676 --> 00:18:33,978
2008 ... NASA's Mars reconnaissance orbiter
360
00:18:33,980 --> 00:18:40,017
flies high over the surface of Mars.
361
00:18:40,019 --> 00:18:41,552
Its ground-penetrating instruments
362
00:18:41,554 --> 00:18:43,521
peer deep below the surface,
363
00:18:43,523 --> 00:18:47,791
aiming to unlock Mars' geological secrets.
364
00:18:47,793 --> 00:18:49,927
As it scans near Mars' equator,
365
00:18:49,929 --> 00:18:53,598
the orbiter spots something that has no right to be there ...
366
00:18:53,600 --> 00:18:57,869
a vast, underground glacier.
367
00:18:57,871 --> 00:19:01,839
One mile thick and three times the size of Los Angeles,
368
00:19:01,841 --> 00:19:06,810
ice on this scale should only form at the frigid poles.
369
00:19:06,812 --> 00:19:08,546
The only explanation ...
370
00:19:08,548 --> 00:19:10,881
Mars must have been tipped over
371
00:19:10,883 --> 00:19:15,485
with its equator tilted away from the sun.
372
00:19:15,487 --> 00:19:16,753
The tilt on Mars' axis
373
00:19:16,755 --> 00:19:19,190
has actually changed significantly over time,
374
00:19:19,192 --> 00:19:21,359
and in non-systematic ways,
375
00:19:21,361 --> 00:19:23,761
it just happens randomly that it will start moving,
376
00:19:23,763 --> 00:19:25,997
and so there are some models that suggest
377
00:19:25,999 --> 00:19:29,133
that Mars has actually been almost tipped over on its end.
378
00:19:32,337 --> 00:19:33,537
Most planets wobble,
379
00:19:33,539 --> 00:19:36,207
and from time to time, they wobble so much
380
00:19:36,209 --> 00:19:41,145
they can tip over, leading to super winters.
381
00:19:41,147 --> 00:19:42,379
If that had happened here on earth,
382
00:19:42,381 --> 00:19:45,482
Los Angeles could become the arctic.
383
00:19:45,484 --> 00:19:47,851
Well, you can imagine something similar would happen on Mars,
384
00:19:47,853 --> 00:19:51,555
how drastic the change would be.
385
00:19:51,557 --> 00:19:53,357
You're used to seeing the sun overhead,
386
00:19:53,359 --> 00:19:55,359
it's very warm, there's probably liquid water,
387
00:19:55,361 --> 00:19:58,262
and as the planet starts going this way,
388
00:19:58,264 --> 00:20:01,332
the sun is not gonna rise as high in the sky.
389
00:20:01,334 --> 00:20:04,735
Eventually you may not see sunrise for half a year,
390
00:20:04,737 --> 00:20:10,307
and any water that's there is gonna be frozen solid.
391
00:20:10,309 --> 00:20:12,143
3.9 billion years ago,
392
00:20:12,145 --> 00:20:15,980
Mars is tilting by as much as 80 degrees.
393
00:20:15,982 --> 00:20:21,452
Winter temperatures drop below minus 125 degrees fahrenheit.
394
00:20:23,221 --> 00:20:26,424
As the polar ice sheet spreads quickly toward the equator,
395
00:20:26,426 --> 00:20:28,626
liquid water is frozen solid,
396
00:20:28,628 --> 00:20:32,296
along with any potential martians.
397
00:20:32,298 --> 00:20:34,498
The water that drives the biochemistry of life
398
00:20:34,500 --> 00:20:38,869
freezes inside the tiny bacteria.
399
00:20:38,871 --> 00:20:42,439
Ice crystals form and puncture the martian's cell walls
400
00:20:42,441 --> 00:20:48,112
until eventually, they die.
401
00:20:48,114 --> 00:20:52,383
Every 120,000 years the tilt of Mars changes,
402
00:20:52,385 --> 00:20:55,185
as again and again the planet's chaotic wobble
403
00:20:55,187 --> 00:21:00,391
flips the martians in and out of the deep freeze.
404
00:21:00,393 --> 00:21:03,995
Any second generation of life on Mars...
405
00:21:03,997 --> 00:21:05,763
Is left in tatters.
406
00:21:14,172 --> 00:21:19,843
Meanwhile, on earth, our ancient ancestors have it easy.
407
00:21:19,845 --> 00:21:23,948
The earth's wobble, and its seasons, stay relatively stable,
408
00:21:23,950 --> 00:21:27,018
and it's all thanks to our secret weapon ...
409
00:21:27,020 --> 00:21:31,622
our oversized moon.
410
00:21:31,624 --> 00:21:33,858
The interaction of our planet and the moon
411
00:21:33,860 --> 00:21:37,227
means that the axis of our rotation is very, very stable.
412
00:21:37,229 --> 00:21:41,298
The seasons return year after year, century after century,
413
00:21:41,300 --> 00:21:45,235
for billions of years.
414
00:21:45,237 --> 00:21:46,570
Our moon's enormous mass
415
00:21:46,572 --> 00:21:49,940
exerts a huge gravitational pull on the earth,
416
00:21:49,942 --> 00:21:52,242
stabilizing the wobble of our planet
417
00:21:52,244 --> 00:21:55,979
and keeping our climate in check.
418
00:21:55,981 --> 00:21:57,714
Without the moon, the early earth
419
00:21:57,716 --> 00:22:00,718
would have wobbled just as wildly as Mars,
420
00:22:00,720 --> 00:22:04,054
and our ancestors could have faced the same icy fate
421
00:22:04,056 --> 00:22:08,058
as the early martians.
422
00:22:08,060 --> 00:22:09,460
Mars doesn't have a big moon,
423
00:22:09,462 --> 00:22:10,328
it has two, little, tiny moons
424
00:22:10,330 --> 00:22:14,065
that don't really affect it much.
425
00:22:14,067 --> 00:22:15,699
So if the martians were killed
426
00:22:15,701 --> 00:22:17,434
the first time by a giant impact,
427
00:22:17,436 --> 00:22:18,902
they may have been killed a second time
428
00:22:18,904 --> 00:22:22,572
by Mars itself not being stable and flipping over
429
00:22:22,574 --> 00:22:27,244
and having catastrophic super winters and super summers,
430
00:22:27,246 --> 00:22:33,284
basically, mega catastrophic climate change.
431
00:22:33,286 --> 00:22:34,752
On Mars, the outlook for life
432
00:22:34,754 --> 00:22:37,455
seems bleak.
433
00:22:37,457 --> 00:22:40,256
But the brutal conditions that drive martian life
434
00:22:40,258 --> 00:22:43,026
to the edge of extinction may also have pushed it
435
00:22:43,028 --> 00:22:46,497
to adapt and evolve.
436
00:22:46,499 --> 00:22:50,468
We know this because on earth organisms known as extremophiles
437
00:22:50,470 --> 00:22:54,004
have evolved to live in the most severe of circumstances,
438
00:22:54,006 --> 00:22:58,075
from boiling, hydro-thermal vents...
439
00:22:58,077 --> 00:23:01,011
To the deep freeze of glacial ice.
440
00:23:01,013 --> 00:23:06,549
When the going gets tough, life seems to get tougher.
441
00:23:06,551 --> 00:23:08,251
Maybe the martian super winters
442
00:23:08,253 --> 00:23:11,355
gave rise to a third generation of life ...
443
00:23:11,357 --> 00:23:14,692
a super tough army of bugs able to survive
444
00:23:14,694 --> 00:23:18,195
the harshest of climate swings.
445
00:23:19,598 --> 00:23:21,732
What we see on earth is that life evolves
446
00:23:21,734 --> 00:23:24,969
to occupy whatever niche it lives in,
447
00:23:24,971 --> 00:23:27,705
and that evolution takes time.
448
00:23:27,707 --> 00:23:31,442
So as the environment changes, life changes with it.
449
00:23:31,444 --> 00:23:32,877
If there are sudden changes,
450
00:23:32,879 --> 00:23:36,580
then life forms can't cope with it and many die away.
451
00:23:36,582 --> 00:23:41,252
Those that survive, they continue on.
452
00:23:41,254 --> 00:23:43,187
3.8 billion years ago
453
00:23:43,189 --> 00:23:45,556
a third generation of life could have thrived
454
00:23:45,558 --> 00:23:48,391
on the surface of Mars.
455
00:23:48,393 --> 00:23:50,795
Evolved from a handful of its predecessors
456
00:23:50,797 --> 00:23:53,597
to make it through Mars' super winters,
457
00:23:53,599 --> 00:23:57,600
it's the toughest martian life yet.
458
00:23:57,602 --> 00:23:59,503
But, as the super winters end,
459
00:23:59,505 --> 00:24:03,407
the challenges for life on Mars are set to get worse.
460
00:24:03,409 --> 00:24:07,077
Another extinction-level event is on the way.
461
00:24:07,079 --> 00:24:12,583
Mars' atmosphere is being ripped away molecule by molecule.
462
00:24:12,585 --> 00:24:14,218
Could this be the killer punch
463
00:24:14,220 --> 00:24:16,253
that wipes out the martians for good?
464
00:24:35,273 --> 00:24:36,473
Imagine Mars
465
00:24:36,475 --> 00:24:40,443
3.8 billion years ago.
466
00:24:40,445 --> 00:24:42,513
It's a warm, wet world,
467
00:24:42,515 --> 00:24:46,950
and super tough bacterial life is thriving.
468
00:24:46,952 --> 00:24:51,589
But these martians are not the planet's first inhabitants.
469
00:24:54,727 --> 00:24:56,861
The first generation of martian is vaporized
470
00:24:56,863 --> 00:25:02,099
by the huge borealis impact.
471
00:25:02,101 --> 00:25:04,034
Perhaps life starts over from scratch,
472
00:25:04,036 --> 00:25:07,738
but endures a series of extreme climate swings.
473
00:25:07,740 --> 00:25:11,441
Only the toughest martians make it through.
474
00:25:17,182 --> 00:25:19,683
But another disaster is about to strike,
475
00:25:19,685 --> 00:25:26,323
and this catastrophe will test even the strongest martians.
476
00:25:26,325 --> 00:25:30,861
They're about to lose the most basic ingredient of life ...
477
00:25:30,863 --> 00:25:32,530
liquid water.
478
00:25:32,532 --> 00:25:34,832
You really have to appreciate how difficult it is
479
00:25:34,834 --> 00:25:37,834
to have liquid water on the surface of a planet.
480
00:25:37,836 --> 00:25:39,736
We know that life works so well
481
00:25:39,738 --> 00:25:41,538
when there's liquid water around.
482
00:25:41,540 --> 00:25:43,540
But you need just the right balance
483
00:25:43,542 --> 00:25:47,044
of air pressure and temperature.
484
00:25:47,046 --> 00:25:48,045
Without air pressure
485
00:25:48,047 --> 00:25:49,546
weighing down on it,
486
00:25:49,548 --> 00:25:52,949
liquid water will evaporate from the surface of a planet,
487
00:25:52,951 --> 00:25:55,553
whatever the temperature.
488
00:25:55,555 --> 00:25:57,121
That air pressure is generated
489
00:25:57,123 --> 00:26:00,624
by the presence of an atmosphere.
490
00:26:00,626 --> 00:26:01,625
In a lot of ways that atmosphere
491
00:26:01,627 --> 00:26:03,093
serves as a kind of a lid
492
00:26:03,095 --> 00:26:05,062
stopping down the water from escaping into space.
493
00:26:05,064 --> 00:26:09,700
It's very important to have that atmosphere.
494
00:26:09,702 --> 00:26:11,735
3.7 billion years ago,
495
00:26:11,737 --> 00:26:16,607
life on earth enjoys warm oceans and a thick atmosphere.
496
00:26:16,609 --> 00:26:19,609
But on Mars, a third extinction-level event
497
00:26:19,611 --> 00:26:21,412
is gaining momentum.
498
00:26:25,984 --> 00:26:29,286
The atmosphere is slowly being stripped away,
499
00:26:29,288 --> 00:26:35,925
and Mars' great oceans are starting to evaporate.
500
00:26:35,927 --> 00:26:37,728
The fate of life on both planets
501
00:26:37,730 --> 00:26:42,566
now rests on the strength of their magnetic cores.
502
00:26:42,568 --> 00:26:44,234
It turns out that the existence
503
00:26:44,236 --> 00:26:48,305
of an atmosphere on earth may rely on the magnetic field,
504
00:26:48,307 --> 00:26:50,174
because what our magnetic field does
505
00:26:50,176 --> 00:26:53,510
is it protects us from the onslaught of this wind,
506
00:26:53,512 --> 00:26:54,778
of subatomic particles
507
00:26:54,780 --> 00:26:57,848
that the sun is blowing out all the time.
508
00:26:57,850 --> 00:26:59,650
We call this the solar wind.
509
00:27:03,387 --> 00:27:04,521
And if we didn't have a magnetic field
510
00:27:04,523 --> 00:27:08,224
to basically catch and deflect those particles gently,
511
00:27:08,226 --> 00:27:12,463
they would directly slam into the earth's atmosphere.
512
00:27:12,465 --> 00:27:14,230
If you think of the magnetic field
513
00:27:14,232 --> 00:27:16,266
as a windbreaker from the solar winds,
514
00:27:16,268 --> 00:27:17,801
once we lose that protection,
515
00:27:17,803 --> 00:27:22,806
that planet becomes very vulnerable.
516
00:27:22,808 --> 00:27:24,040
The earth's magnetic core
517
00:27:24,042 --> 00:27:27,477
has stayed strong for 3.45 billion years
518
00:27:27,479 --> 00:27:31,248
as super hot molten iron churns over and over
519
00:27:31,250 --> 00:27:35,585
within the planet like a lava lamp.
520
00:27:35,587 --> 00:27:37,721
Churning iron creates electricity,
521
00:27:37,723 --> 00:27:40,290
which in turn generates a magnetic field
522
00:27:40,292 --> 00:27:44,861
that rises up around the earth, acting like a magnetic shield,
523
00:27:44,863 --> 00:27:49,466
protecting our atmosphere from the ravages of the solar wind.
524
00:27:49,468 --> 00:27:50,934
3.8 billion years ago
525
00:27:50,936 --> 00:27:54,438
Mars had a molten core and a magnetic field.
526
00:27:54,440 --> 00:27:58,142
But something caused its shield to drop.
527
00:27:58,144 --> 00:28:02,713
Did Mars' small molten core simply get too cold to function?
528
00:28:02,715 --> 00:28:04,081
Or did something else kickstart
529
00:28:04,083 --> 00:28:07,751
this third great extinction of martian life?
530
00:28:07,753 --> 00:28:10,787
A new and controversial theory points the finger
531
00:28:10,789 --> 00:28:14,525
partly at the ancient borealis impact.
532
00:28:17,496 --> 00:28:19,096
A giant impact of this scale
533
00:28:19,098 --> 00:28:21,398
can affect a range of temperatures,
534
00:28:21,400 --> 00:28:25,735
from the hot inner core to the cooler outer mantle.
535
00:28:25,737 --> 00:28:27,404
4.5 billion years ago
536
00:28:27,406 --> 00:28:29,339
the impact that vaporizes
537
00:28:29,341 --> 00:28:31,675
the first generation of martian life
538
00:28:31,677 --> 00:28:35,011
also drives heat into the planet,
539
00:28:35,013 --> 00:28:38,515
increasing the temperatures in the outer mantle.
540
00:28:38,517 --> 00:28:41,251
The heat inside the planet evens out,
541
00:28:41,253 --> 00:28:44,855
and the metals slowly stop churning.
542
00:28:44,857 --> 00:28:46,724
But there's less of a temperature gradient ...
543
00:28:46,726 --> 00:28:49,526
that makes it harder for this dyno process to,
544
00:28:49,528 --> 00:28:52,796
to drive a strong magnetic field.
545
00:28:52,798 --> 00:28:53,930
Over hundreds of millions
546
00:28:53,932 --> 00:29:00,270
of years, Mars' magnetic field shuts down.
547
00:29:00,272 --> 00:29:01,605
When Mars lost its magnetic
548
00:29:01,607 --> 00:29:03,073
field all of a sudden
549
00:29:03,075 --> 00:29:05,509
it was completely vulnerable to the solar wind.
550
00:29:05,511 --> 00:29:07,076
The solar wind could break apart
551
00:29:07,078 --> 00:29:09,346
and carry away the martian atmosphere.
552
00:29:17,489 --> 00:29:19,422
3.7 billion years ago
553
00:29:19,424 --> 00:29:24,094
super tough martian life faces annihilation.
554
00:29:24,096 --> 00:29:28,899
Bit by bits, the atmosphere is being swept into space.
555
00:29:28,901 --> 00:29:31,735
The air pressure is dropping across the planet
556
00:29:31,737 --> 00:29:35,605
and most of Mars' water has already boiled away.
557
00:29:38,910 --> 00:29:40,344
The chances of survival
558
00:29:40,346 --> 00:29:43,814
without this precious liquid are remote.
559
00:29:43,816 --> 00:29:47,584
But, for the martians, there's an even more immediate danger.
560
00:29:47,586 --> 00:29:51,355
With no magnetic field and no thick atmosphere,
561
00:29:51,357 --> 00:29:54,324
the surface of Mars feels the full force
562
00:29:54,326 --> 00:29:57,394
of the sun's radiation.
563
00:30:03,835 --> 00:30:05,002
If you're a microbe
564
00:30:05,004 --> 00:30:06,269
on the surface,
565
00:30:06,271 --> 00:30:07,371
you would have to make do
566
00:30:07,373 --> 00:30:09,706
with very little atmosphere, no water,
567
00:30:09,708 --> 00:30:11,642
this flood of ultraviolet light from the sun,
568
00:30:11,644 --> 00:30:14,511
and these particles which are slamming into you all the time.
569
00:30:17,615 --> 00:30:18,982
The martians are bombarded
570
00:30:18,984 --> 00:30:21,618
by radiation from the solar wind.
571
00:30:21,620 --> 00:30:25,622
It rips their DNA apart.
572
00:30:25,624 --> 00:30:27,023
Without an atmosphere,
573
00:30:27,025 --> 00:30:30,627
the surface of the planet is sterilized.
574
00:30:30,629 --> 00:30:35,031
But is this really the end for martian life?
575
00:30:35,033 --> 00:30:36,567
Life is so tenacious,
576
00:30:36,569 --> 00:30:40,470
it can survive even those incredible catastrophic changes,
577
00:30:40,472 --> 00:30:43,507
and it may still be there today.
578
00:30:43,509 --> 00:30:45,175
To survive the radiation,
579
00:30:45,177 --> 00:30:49,646
martian life would have had to have moved deep underground.
580
00:30:51,749 --> 00:30:54,217
In this protected subterranean environment
581
00:30:54,219 --> 00:30:57,720
it may also have found a source of liquid water,
582
00:30:57,722 --> 00:30:59,122
and if that happened,
583
00:30:59,124 --> 00:31:02,292
could the martians still be there today,
584
00:31:02,294 --> 00:31:06,897
waiting for us to drop in and say hello?
585
00:31:25,249 --> 00:31:26,683
Since the 1960s
586
00:31:26,685 --> 00:31:28,585
robotic probes and landers
587
00:31:28,587 --> 00:31:34,090
have been searching the surface of Mars for signs of life.
588
00:31:34,092 --> 00:31:37,427
But have they been looking in the right places?
589
00:31:37,429 --> 00:31:39,630
The surface of Mars is a waterless desert
590
00:31:39,632 --> 00:31:43,700
that's bombarded by harmful radiation.
591
00:31:43,702 --> 00:31:47,637
If a fourth incarnation of martian life is alive today,
592
00:31:47,639 --> 00:31:53,042
many scientists think it'll have to be deep underground.
593
00:31:53,044 --> 00:31:54,177
Underneath the surface of Mars
594
00:31:54,179 --> 00:31:56,446
you may have all the conditions you need for life.
595
00:31:56,448 --> 00:31:58,281
There may be some liquid water down there,
596
00:31:58,283 --> 00:32:00,984
and you're also protected from the intense radiation
597
00:32:00,986 --> 00:32:02,386
that you find on the surface.
598
00:32:06,524 --> 00:32:08,091
Scientists are split
599
00:32:08,093 --> 00:32:13,630
on the best underground places to search for martian life.
600
00:32:13,632 --> 00:32:15,432
But if jani radebaugh were on Mars,
601
00:32:15,434 --> 00:32:19,703
she would head to the nearest sand dune and start digging.
602
00:32:22,240 --> 00:32:23,340
Here you can see
603
00:32:23,342 --> 00:32:25,542
this is wet sand just below the surface.
604
00:32:25,544 --> 00:32:30,046
This is the perfect environment to be able to house life.
605
00:32:30,048 --> 00:32:32,282
Even in the very driest deserts on earth,
606
00:32:32,284 --> 00:32:34,651
in between the sand dunes, in the inter-dunes,
607
00:32:34,653 --> 00:32:37,554
you can find water percolating up from Springs
608
00:32:37,556 --> 00:32:39,556
that come up from deep under the ground,
609
00:32:39,558 --> 00:32:41,425
perfect for life to form and grow.
610
00:32:41,427 --> 00:32:43,493
And if you just keep on digging...
611
00:32:43,495 --> 00:32:46,029
Down into the bottom of the inter-dune,
612
00:32:46,031 --> 00:32:48,332
maybe you would reach the water table.
613
00:32:48,334 --> 00:32:50,434
And if you reach the water table on Mars,
614
00:32:50,436 --> 00:32:53,770
now you have all the conditions just right for life.
615
00:32:53,772 --> 00:32:55,839
This is my bet, this is where I'd go,
616
00:32:55,841 --> 00:32:59,175
right between the dunes.
617
00:32:59,177 --> 00:33:00,577
Digging for martian life
618
00:33:00,579 --> 00:33:02,612
in the desert is one option.
619
00:33:02,614 --> 00:33:05,849
But some scientists have very different ideas,
620
00:33:05,851 --> 00:33:08,184
and planetary scientist Nina lanza
621
00:33:08,186 --> 00:33:12,722
would need to pack a rope and a flashlight for her search.
622
00:33:12,724 --> 00:33:14,457
So if were to go to Mars to find life,
623
00:33:14,459 --> 00:33:15,959
I would go to a lava tube.
624
00:33:18,229 --> 00:33:19,096
Lava tubes are made
625
00:33:19,098 --> 00:33:21,297
by ancient volcanoes,
626
00:33:21,299 --> 00:33:25,335
the empty leftovers from underground lava flows.
627
00:33:25,337 --> 00:33:27,437
Today, they form deep tunnels,
628
00:33:27,439 --> 00:33:29,473
shielded from radiation and shut off
629
00:33:29,475 --> 00:33:32,475
from the harsh martian climate.
630
00:33:32,477 --> 00:33:33,477
We've never been
631
00:33:33,479 --> 00:33:35,145
in a lava tube on Mars,
632
00:33:35,147 --> 00:33:40,283
but it is absolutely possible that there's liquid water.
633
00:33:40,285 --> 00:33:43,353
So, that's an environment where you could have some moisture,
634
00:33:43,355 --> 00:33:46,189
you could have a little warmth, you're protected from radiation.
635
00:33:46,191 --> 00:33:50,093
I think that a martian microbe would be very happy there.
636
00:33:54,266 --> 00:33:55,432
Finding life on Mars
637
00:33:55,434 --> 00:33:58,435
would be a monumental human accomplishment.
638
00:33:58,437 --> 00:34:00,070
But there is a danger.
639
00:34:00,072 --> 00:34:03,607
By exposing martian life to life from earth,
640
00:34:03,609 --> 00:34:07,911
could we unwittingly set off yet another extinction event?
641
00:34:07,913 --> 00:34:09,312
Humans have been
642
00:34:09,314 --> 00:34:12,315
one of the most effective extinction mechanisms
643
00:34:12,317 --> 00:34:14,450
of life on earth.
644
00:34:14,452 --> 00:34:16,285
The interesting question will be,
645
00:34:16,287 --> 00:34:19,689
will we produce a similar calamity on Mars?
646
00:34:19,691 --> 00:34:21,424
If humans someday go to Mars,
647
00:34:21,426 --> 00:34:23,560
then we will be an invasive species,
648
00:34:23,562 --> 00:34:25,228
and if there is some martian life
649
00:34:25,230 --> 00:34:27,097
that's hanging on in some niche,
650
00:34:27,099 --> 00:34:29,466
we could be their ultimate destroyers.
651
00:34:29,468 --> 00:34:31,868
So we have an ethical responsibility
652
00:34:31,870 --> 00:34:36,807
to preserve whatever life may be on Mars.
653
00:34:36,809 --> 00:34:38,608
The problem isn't us,
654
00:34:38,610 --> 00:34:42,345
it's the bugs in and on our bodies.
655
00:34:42,347 --> 00:34:43,413
The average human has
656
00:34:43,415 --> 00:34:47,650
ten to 20 trillion bacterial hitchhikers.
657
00:34:47,652 --> 00:34:48,918
If we go to Mars,
658
00:34:48,920 --> 00:34:51,888
we'll be taking our tiny companions along for the ride,
659
00:34:51,890 --> 00:34:55,024
and any one of those bugs could turn out to be
660
00:34:55,026 --> 00:34:58,161
a deadly competitor for martian life.
661
00:35:01,332 --> 00:35:03,333
It's NASA engineer moogega Cooper's
662
00:35:03,335 --> 00:35:07,403
job to keep Mars rovers bug-free.
663
00:35:07,405 --> 00:35:11,974
But keeping astronauts clean, that's a whole different matter.
664
00:35:11,976 --> 00:35:13,743
We bake our spacecraft hardware
665
00:35:13,745 --> 00:35:17,147
at 110 degrees celsius for at least 50 hours
666
00:35:17,149 --> 00:35:19,882
to prevent the contamination of Mars.
667
00:35:19,884 --> 00:35:23,386
But unlike spacecraft, we cannot bake humans out.
668
00:35:23,388 --> 00:35:25,856
We will not survive those temperatures.
669
00:35:30,862 --> 00:35:31,928
Unless we find a way
670
00:35:31,930 --> 00:35:34,297
to keep astronauts bug-free,
671
00:35:34,299 --> 00:35:37,166
exploring Mars with robots is our best option
672
00:35:37,168 --> 00:35:41,838
for keeping the martians safe from harm.
673
00:35:41,840 --> 00:35:43,707
But what will happen when our robots
674
00:35:43,709 --> 00:35:47,644
finally find that life and we look deep into the workings
675
00:35:47,646 --> 00:35:50,680
of our extraterrestrial neighbors?
676
00:35:52,550 --> 00:35:56,719
What will the martians turn out to be like?
677
00:35:56,721 --> 00:35:59,689
Our example where DNA is the organic molecule
678
00:35:59,691 --> 00:36:00,957
that carries the information of life ...
679
00:36:00,959 --> 00:36:02,291
we don't even know
680
00:36:02,293 --> 00:36:05,628
if that's gonna be the rulebook in other places.
681
00:36:05,630 --> 00:36:07,631
Finding any evidence whatsoever on Mars
682
00:36:07,633 --> 00:36:11,768
would help us better understand what else is possible.
683
00:36:14,171 --> 00:36:15,171
Will the martians
684
00:36:15,173 --> 00:36:17,007
be different than us?
685
00:36:17,009 --> 00:36:19,042
Made from different materials
686
00:36:19,044 --> 00:36:22,145
and with a different biochemistry?
687
00:36:22,147 --> 00:36:26,149
Or will they seem shockingly familiar?
688
00:36:26,151 --> 00:36:29,452
Some scientists think that the very first martian life
689
00:36:29,454 --> 00:36:32,322
may not have stayed on Mars.
690
00:36:32,324 --> 00:36:34,991
It may have come here.
691
00:36:34,993 --> 00:36:36,492
It's not that farfetched to think
692
00:36:36,494 --> 00:36:38,928
that life could have jumped from Mars
693
00:36:38,930 --> 00:36:41,798
or been a back and forth from Mars to earth.
694
00:36:41,800 --> 00:36:43,733
If the martians came to earth,
695
00:36:43,735 --> 00:36:46,536
could they have seeded life on our planet?
696
00:36:46,538 --> 00:36:48,938
Maybe the martians aren't dead.
697
00:36:48,940 --> 00:36:51,007
Maybe I'm a martian, maybe you're a martian.
698
00:37:12,630 --> 00:37:15,798
We've sent a robot army to Mars,
699
00:37:15,800 --> 00:37:18,368
and what it's found is astonishing.
700
00:37:18,370 --> 00:37:21,838
The possibility that life could have arisen there,
701
00:37:21,840 --> 00:37:24,541
perhaps more than once,
702
00:37:24,543 --> 00:37:28,210
with different generations of martians emerging from the ashes
703
00:37:28,212 --> 00:37:31,248
of catastrophic extinction events.
704
00:37:33,451 --> 00:37:36,052
Life could still be sheltering
705
00:37:36,054 --> 00:37:40,523
below the surface of Mars right now.
706
00:37:42,993 --> 00:37:46,562
But there's another possibility that's truly astounding ...
707
00:37:46,564 --> 00:37:50,299
that martians aren't just hiding out on Mars,
708
00:37:50,301 --> 00:37:53,770
they're thriving, right here on earth.
709
00:37:57,341 --> 00:37:58,408
I might be a martian,
710
00:37:58,410 --> 00:38:00,777
you might be a martian.
711
00:38:00,779 --> 00:38:03,012
We might be from another planet.
712
00:38:03,014 --> 00:38:07,083
We might have already travelled and lived on two planets
713
00:38:07,085 --> 00:38:09,786
as life forms ... not as a species, certainly,
714
00:38:09,788 --> 00:38:13,256
but our ancestors may have come from another planet,
715
00:38:13,258 --> 00:38:16,893
and that is mind blowing.
716
00:38:16,895 --> 00:38:18,728
The idea that our ancestors
717
00:38:18,730 --> 00:38:21,564
could be martians is a new take on an old theory
718
00:38:21,566 --> 00:38:24,901
called panspermia.
719
00:38:24,903 --> 00:38:25,835
According to the theory,
720
00:38:25,837 --> 00:38:28,237
life on earth began when a space rock
721
00:38:28,239 --> 00:38:31,341
filled with alien bacteria landed on the earth
722
00:38:31,343 --> 00:38:34,778
and every living thing we see today, including us,
723
00:38:34,780 --> 00:38:39,515
evolved from those cosmic hitchhikers.
724
00:38:39,517 --> 00:38:42,518
The idea of panspermia has been around for centuries,
725
00:38:42,520 --> 00:38:44,620
but had a resurgence when scientists
726
00:38:44,622 --> 00:38:48,858
determined that life on earth may go back four billion years,
727
00:38:48,860 --> 00:38:51,961
to the end of a sustained attack of asteroid showers
728
00:38:51,963 --> 00:38:56,366
known as the late heavy bombardment.
729
00:38:56,368 --> 00:38:59,001
There are a lot of objects from the outer solar system ...
730
00:38:59,003 --> 00:39:00,603
comets and asteroids, all kinds of things ...
731
00:39:00,605 --> 00:39:02,338
coming into the inner solar system
732
00:39:02,340 --> 00:39:05,374
and slamming into the planets.
733
00:39:05,376 --> 00:39:06,676
Conventional wisdom
734
00:39:06,678 --> 00:39:09,612
suggests the objects hitting the earth at the time
735
00:39:09,614 --> 00:39:11,347
were leftover debris
736
00:39:11,349 --> 00:39:14,250
from the formation of the solar system.
737
00:39:14,252 --> 00:39:16,553
But a very controversial idea
738
00:39:16,555 --> 00:39:22,959
suggests these space rocks were actually all pieces of Mars,
739
00:39:22,961 --> 00:39:26,262
thrown off in the borealis space impact
740
00:39:26,264 --> 00:39:30,500
when a huge object blasted into Mars.
741
00:39:30,502 --> 00:39:36,406
The timing links up really well for the borealis space impact.
742
00:39:36,408 --> 00:39:39,008
If you calculate how much debris
743
00:39:39,010 --> 00:39:40,844
that would have been thrown out into space
744
00:39:40,846 --> 00:39:43,579
and when it would have had to have happened,
745
00:39:43,581 --> 00:39:45,748
according to the martian geologic record,
746
00:39:45,750 --> 00:39:49,118
it coincides with the late heavy bombardment...
747
00:39:53,792 --> 00:39:56,359
It's possible that the debris
748
00:39:56,361 --> 00:39:57,994
from the borealis space in forming impact
749
00:39:57,996 --> 00:40:00,997
might have come to earth and rained down on us
750
00:40:00,999 --> 00:40:02,665
and made the late heavy bombardment,
751
00:40:02,667 --> 00:40:06,202
seeding the earth with bacterial spores from Mars.
752
00:40:06,204 --> 00:40:08,905
Now, this is just a hypothesis, we don't know this for certain,
753
00:40:08,907 --> 00:40:10,306
we don't have evidence.
754
00:40:10,308 --> 00:40:13,443
But it is physically possible for that to have happened.
755
00:40:15,647 --> 00:40:16,980
Was the earth seeded
756
00:40:16,982 --> 00:40:18,481
by microscopic martians
757
00:40:18,483 --> 00:40:23,853
blown into space by the borealis impact?
758
00:40:23,855 --> 00:40:27,890
It sounds crazy, but the science stacks up.
759
00:40:27,892 --> 00:40:30,026
We know that simple life is tough,
760
00:40:30,028 --> 00:40:33,830
able to survive in the cold vacuum of space,
761
00:40:33,832 --> 00:40:35,898
and the timing of the borealis impact
762
00:40:35,900 --> 00:40:41,704
works out well for the rise of the first organisms on earth.
763
00:40:42,873 --> 00:40:46,175
Crucially, we know that rocks ejected from Mars
764
00:40:46,177 --> 00:40:48,377
can make it all the way to earth
765
00:40:48,379 --> 00:40:53,182
because they're still crash landing here, even today.
766
00:40:53,184 --> 00:40:55,285
One of the coolest things I've done as a scientist
767
00:40:55,287 --> 00:40:57,187
is held a piece of Mars in my hands.
768
00:40:57,189 --> 00:41:00,490
Now, we never had a mission that returned a sample from Mars,
769
00:41:00,492 --> 00:41:02,358
we had to come about it a different way.
770
00:41:02,360 --> 00:41:03,960
And it turns out we have meteorites
771
00:41:03,962 --> 00:41:07,664
that we are 100% sure are bits of Mars.
772
00:41:07,666 --> 00:41:10,233
They were actually exploded out during huge collisions,
773
00:41:10,235 --> 00:41:12,235
and eventually they fell on the earth.
774
00:41:18,176 --> 00:41:19,675
Four different generations
775
00:41:19,677 --> 00:41:21,677
of martians, each of them facing
776
00:41:21,679 --> 00:41:25,548
a different planetary catastrophe.
777
00:41:25,550 --> 00:41:27,116
But despite enormous odds,
778
00:41:27,118 --> 00:41:29,786
martians could still be alive today,
779
00:41:29,788 --> 00:41:32,856
buried deep under the surface of Mars,
780
00:41:32,858 --> 00:41:37,393
or maybe even thriving on earth.
781
00:41:37,395 --> 00:41:39,362
If life is really that tenacious
782
00:41:39,364 --> 00:41:41,764
that it can come back and keep coming back
783
00:41:41,766 --> 00:41:42,965
and keep coming back,
784
00:41:42,967 --> 00:41:45,634
that gives me a lot of hope for life in the universe.
785
00:41:45,636 --> 00:41:48,637
That tells me that life is maybe tough,
786
00:41:48,639 --> 00:41:53,409
maybe individuals are fragile, but maybe life itself is tough.
787
00:41:53,411 --> 00:41:54,544
For now,
788
00:41:54,546 --> 00:41:56,813
all we can do is speculate
789
00:41:56,815 --> 00:41:59,649
until future generations develop the technology
790
00:41:59,651 --> 00:42:01,984
to visit the red planet
791
00:42:01,986 --> 00:42:07,190
and grab our first sample of extraterrestrial life.
792
00:42:07,192 --> 00:42:09,158
That's going to change everything.
793
00:42:09,160 --> 00:42:10,360
We're going to have another example
794
00:42:10,362 --> 00:42:12,628
of how life started and how life works.
795
00:42:12,630 --> 00:42:14,663
And even if it's something that's dead,
796
00:42:14,665 --> 00:42:15,798
we knew it was there.
797
00:42:15,800 --> 00:42:18,167
The universe will never be the same again.
62071
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