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Our neighbor, Mars,
fascinates us.
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It's a planet
that is similar to Earth,
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but with some big differences.
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Mars is rusty, dusty,
frigid, and frozen.
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It ain't the kind of place
you want to raise your kids.
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Past missions suggest that Mars
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was once a very different world.
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The Mars we see today has
completely changed
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from the Mars of
a few billion years ago.
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From the Mars of
a few billion years ago.
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If I had
a time machine to visit Mars
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in the past,
I would go in an instant.
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Without a time machine
to explore
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ancient Mars,
we employ a team of high-tech
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robot investigators.
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We've got an entire fleet
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of robotic spacecraft
exploring the planet.
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Working together, they dig
into Mars's past to answer
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the ultimate question...
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Did Mars once have life?
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Did Mars once have life?
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February 2021.
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The newest robot investigator
speeds towards Mars,
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the most advanced rover
NASA has ever sent to
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another world.
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Another world.
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This is Perseverance.
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The goal of
the Perseverance mission is
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to look for signs of
past life on Mars.
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First, it must navigate safely
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to the surface of the planet.
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Every landing
has its own dangers.
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Because the rover must
be autonomous,
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it has to do everything
without our help.
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Perseverance enters
Mars's thin atmosphere at
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close to 12,500 miles an hour...
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close to 12,500 miles an hour...
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and deploys a parachute.
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The parachute slows Perseverance
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to 200 miles per hour.
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Still too fast to land safely.
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Still too fast to land safely.
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To prevent a violent impact,
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the rover must activate
the sky crane.
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When I first saw
the sky crane concept,
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I thought, hm, the engineers
are kind of losing it.
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It seemed to me like
a really crazy idea.
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Perseverance
activates its jetpack.
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Retro rockets slow
the lander's descent to a crawl.
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Then, 66 feet above the surface,
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the sky crane uses cables to
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gently lower the rover
to the ground.
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Step one in
the search for Martian life,
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find evidence of liquid water.
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A good place to start is
the 28-mile-wide
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Jezero Crater.
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Perseverance has landed in
a crater called Jezero, and this
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looks like a place where there
was liquid water in its past.
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And the reason we think this
is because
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there's this beautiful delta
deposit right in the middle.
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There's this beautiful delta
deposit right in the middle.
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Perseverance turns
its high-resolution cameras
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onto a cliff side in the crater
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and discovers giant five-foot
boulders near the top.
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A clue to how they got there may
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come from the first probes
to visit Mars.
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One of the very first things
we noticed about Mars
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when we first sent probes there
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with Mariner and Viking was
that there were these huge
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channels on the surface of Mars.
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Channels on the surface of Mars.
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Looking at
these enormous landforms,
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we realized that,
in some places on Mars,
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there may have been
enormous floods,
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bigger than almost anything
we'd ever seen on Earth.
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Flash floods on Earth
cause similar rock formations to
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those found in Jezero Crater,
suggesting that powerful,
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fast-moving torrents carried
the giant rocks found by
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Perseverance and dumped them
at the top of the cliff.
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Perseverance is just one
member of an elite team
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of robots patrolling the ground
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and spying from the air.
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The Mars Atmospheric
and Volatile Evolution
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Orbiter, or MAVEN,
investigates Mars's atmosphere.
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MAVEN smells really good.
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It smells
the Martian atmosphere.
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It tells us what
the Martian atmosphere
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is made of all across
the planet.
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Is made of all across
the planet.
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Then there's the MARS
Reconnaissance Orbiter.
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As its name suggests,
an orbiting spacecraft
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that images surface of MARS.
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The M.R.O.'s
high-resolution cameras
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can identify surface features as
small as a kitchen table.
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And joining the orbital crew,
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The European Space Agency's
MARS Express.
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With its
ground-penetrating radar,
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it searches for evidence of
subsurface water.
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It searches for evidence of
subsurface water.
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And, on the Martian surface,
a group of high-tech landers
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take a closer look,
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including the team's quake
specialist, Insight.
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This lander probes
deep beneath the surface
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to discover how Mars's interior
shapes the planet over time.
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The Insight lander on MARS has
a really simple concept.
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You land a spacecraft
on the surface anywhere
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on Mars and then just listen
for Mars quakes.
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And 300 miles south of
Insight, veteran rover,
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Curiosity is exploring
the Gale Crater.
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The mission goal for Curiosity
is to look for habitability,
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and so that's environments
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in which life as we currently
understand it could exist.
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Curiosity searches
for evidence of calmer,
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more permanent water in
Mars's past.
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Investigating layers of rock
at the base of Mount Sharp,
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Investigating layers of rock
at the base of Mount Sharp,
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a three-mile-high mountain in
the middle of the crater.
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The rock layers
start way up at the top of
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Mount Sharp, and they move
progressively downward,
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and basically, we're going
backwards in time until we get
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to the very bottom, and the very
bottom is actually really old.
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Mount Sharp was built
over millions of years,
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layer by layer.
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The rocks at the base of
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the mountain date to
3.5 billion years ago.
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These rocks are made up
of very fine layers
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These rocks are made up
of very fine layers
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and could only have been
formed in calm water.
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These sedimentary layers were
formed when Gale Crater was
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a lake, and sediment settles
out, and you get these
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beautiful layers.
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Curiosity explores
more of Gale Crater
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and discovers rounded pebbles,
like those we find on Earth.
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When you see a rounded
pebble on Earth,
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you know that that got rounded
in a river channel.
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You know that that got rounded
in a river channel.
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Some of them used to be angular,
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but their angles all got
knocked off by being rolled
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and rounded and moved by water.
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So we're very excited when
we see rounded pebbles on Mars.
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The rock layers
and rounded pebbles
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tell us that over
three billion years ago,
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Gale Crater
was a lake fed by rivers.
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It was so exciting
to understand liquid
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water in the context of
Gale Crater,
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where Curiosity is, and that's
just because what we see there
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where Curiosity is, and that's
just because what we see there
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is this long-lasting,
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freshwater lake, and that's
not like anything else
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we've seen on Mars before.
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Imagine standing on the edge
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and looking out
at this big, beautiful
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blue lake
shining in the distance.
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What if there were just
a whole array
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of craters filled with water
off in the distance?
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It would be so beautiful.
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And a good place
for life to evolve.
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Mars was a nice place.
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Mars was a nice place.
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It was probably more like
Earth is now.
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So it wouldn't surprise me
if it's supported life.
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We're talking microbial life.
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We're not talking, you know,
Marvin the Martian or anything
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like that,
but life still is life.
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Any water Mars once had
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is now long gone.
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To stay liquid,
water needs warmth
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and atmospheric pressure.
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So, hundreds of miles
above the planet,
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orbiting members of the team
investigate the mystery of
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Mars's missing atmosphere.
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While robot team members,
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Curiosity and Perseverance,
work the Martian surface,
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eight probes orbit the planet,
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searching for clues about
Mars's ancient wet history.
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Leading the pack is MAVEN.
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Its mission...
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Its mission...
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To solve the mystery of
Mars's lost atmosphere.
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Today, the atmosphere of Mars
is incredibly thin.
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It's only about 1 percent
the atmospheric pressure
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here on Earth.
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The weight of gas in
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an atmosphere pressing down
creates pressure,
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and that pressure dictates at
what temperature liquids boil.
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Here on Earth at sea level,
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Here on Earth at sea level,
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the boiling point of water
is about 212 degrees Fahrenheit,
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but up here in the mountains
near Denver,
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we're at a higher altitude.
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We've got a lot less
atmosphere pressing down on us,
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and so it boils
at a lower temperature.
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Let's put a thermometer in here.
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There's 200 even right there.
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That's a lot cooler boiling
temperature than at sea level.
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Now, if you go to even higher
altitudes at 100,000 feet
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here on the Earth,
the air pressure is about
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here on the Earth,
the air pressure is about
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what it is
on the surface of Mars.
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00:11:15,567 --> 00:11:16,899
On the surface of Mars,
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water will boil effectively
at ambient temperature.
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00:11:19,667 --> 00:11:21,142
We wouldn't have
to heat it at all.
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00:11:21,166 --> 00:11:22,643
You just put a glass of water on
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the surface of Mars, and it'll
boil and disappear away.
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But the planet's surface
tells us that dry Mars
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was very different in the past.
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00:11:33,866 --> 00:11:36,942
When you see things
like river channels
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that probably took millions
of years to carve,
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that gives you an idea that
the atmosphere was once very,
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very different.
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Very different.
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It had to be thick to allow
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liquid water to exist on
the surface.
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To investigate
what happened to that thick
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Martian atmosphere,
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MAVEN swings into action.
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00:11:57,966 --> 00:11:59,126
One of the main objectives of
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the MAVEN mission was to
measure argon on Mars.
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00:12:02,866 --> 00:12:05,600
There are slightly different
kinds of argon.
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00:12:05,667 --> 00:12:06,866
We call these isotopes,
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and basically,
it means that there's just
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an extra neutron in the nucleus.
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00:12:11,000 --> 00:12:12,423
So there's one type of argon
that's just a little bit
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00:12:12,447 --> 00:12:13,043
So there's one type of argon
that's just a little bit
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heavier than the other type
just by one neutron,
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not by much.
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High up in the atmosphere,
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MAVEN tag teams with Curiosity
down on the surface.
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They measure the amount of
light and heavy argon.
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00:12:31,567 --> 00:12:33,265
Now, what's special about argon?
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Well, argon
is not very reactive,
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00:12:35,466 --> 00:12:37,142
doesn't really get involved in
a lot of chemistry.
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It's not really absorbed by
rocks, doesn't change much.
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Once it's emitted,
it kind of hangs around.
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And that makes it very
valuable, because it means it
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stays in pretty much
its pristine, pure form
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through the history
of the planet.
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00:12:50,567 --> 00:12:52,299
When the researchers
back on Earth
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00:12:52,366 --> 00:12:55,743
compare the readings from
the two Martian robots,
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00:12:55,767 --> 00:12:57,842
something doesn't add up.
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00:12:57,866 --> 00:12:59,442
With Curiosity
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00:12:59,466 --> 00:13:02,442
on the surface, we see
a certain ratio of heavy
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00:13:02,466 --> 00:13:03,866
to light argon.
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00:13:03,966 --> 00:13:07,667
And we expect that same ratio to
exist up in the atmosphere,
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00:13:07,767 --> 00:13:11,543
but with MAVEN,
we see a different ratio.
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00:13:11,567 --> 00:13:12,424
We see far less
of the light argon
247
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We see far less
of the light argon
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00:13:14,265 --> 00:13:15,799
than we do down on the surface.
249
00:13:15,866 --> 00:13:18,567
So something is
messing with that ratio.
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00:13:20,466 --> 00:13:23,000
The only thing we can think of
that can mess with
251
00:13:23,066 --> 00:13:26,866
the ratio of argon is
the solar wind from the sun.
252
00:13:32,265 --> 00:13:34,100
The sun spits out a constant
253
00:13:34,165 --> 00:13:37,500
stream of particles
called the solar wind.
254
00:13:37,567 --> 00:13:40,667
The wind is over a million
degrees Fahrenheit
255
00:13:40,767 --> 00:13:42,423
and travels at up to
500 miles a second.
256
00:13:42,447 --> 00:13:44,008
And travels at up to
500 miles a second.
257
00:13:45,265 --> 00:13:47,667
When it reaches Mars,
it strips away
258
00:13:47,767 --> 00:13:50,500
gases high up in the atmosphere.
259
00:13:50,567 --> 00:13:52,100
The lighter the argon is,
260
00:13:52,165 --> 00:13:54,466
the higher it gets up into
the atmosphere.
261
00:13:54,567 --> 00:13:55,842
That means that that gets blown
262
00:13:55,866 --> 00:13:58,567
away preferentially
by the solar wind.
263
00:13:58,667 --> 00:14:00,366
The heavier argon stays
a little bit
264
00:14:00,466 --> 00:14:02,700
lower down and a little bit
more protected.
265
00:14:02,767 --> 00:14:05,842
So when you look at the ratio
in the atmosphere of the light
266
00:14:05,866 --> 00:14:07,399
argon to the heavy argon,
267
00:14:07,466 --> 00:14:10,567
it gives you an idea of how
much has been lost over time.
268
00:14:13,100 --> 00:14:15,842
MAVEN's data reveals that Mars
269
00:14:15,866 --> 00:14:18,700
has lost 65 percent of the argon
270
00:14:18,767 --> 00:14:22,466
from its atmosphere,
and the solar wind continues to
271
00:14:22,567 --> 00:14:23,767
bombard the planet.
272
00:14:24,799 --> 00:14:27,399
The atmosphere of Mars is
being stripped away by
273
00:14:27,466 --> 00:14:31,166
solar radiation by a quarter
of a pound every second.
274
00:14:32,567 --> 00:14:36,265
This rate of atmospheric
loss leads to one conclusion.
275
00:14:37,366 --> 00:14:41,299
The solar wind
robbed Mars of its once
276
00:14:41,366 --> 00:14:42,423
thick atmosphere, and with it,
the planet's water.
277
00:14:42,447 --> 00:14:45,399
Thick atmosphere, and with it,
the planet's water.
278
00:14:46,667 --> 00:14:48,000
But a question remains.
279
00:14:49,767 --> 00:14:52,265
We know that Mars's
atmosphere was much thicker
280
00:14:52,366 --> 00:14:54,866
in the past,
really similar to Earth's.
281
00:14:54,966 --> 00:14:57,000
So why is it
that Earth's atmosphere
282
00:14:57,100 --> 00:14:58,200
is still mostly there,
283
00:14:58,265 --> 00:15:00,399
whereas Mars's has been
stripped away?
284
00:15:02,299 --> 00:15:04,000
Earth has a protector,
285
00:15:05,100 --> 00:15:08,166
a magnetic field
that shields our atmosphere
286
00:15:08,265 --> 00:15:10,366
from the ravages
of the solar wind.
287
00:15:11,799 --> 00:15:12,424
The Earth's
magnetic field is generated
288
00:15:12,448 --> 00:15:13,942
The Earth's
magnetic field is generated
289
00:15:13,966 --> 00:15:15,100
deep in the core.
290
00:15:15,166 --> 00:15:16,241
There are actually two cores.
291
00:15:16,265 --> 00:15:19,299
There's a solid inner core
and a liquid outer core,
292
00:15:19,366 --> 00:15:21,200
and that solid inner core
is delivering
293
00:15:21,265 --> 00:15:24,100
heat to the outer core,
and as it does this,
294
00:15:24,166 --> 00:15:25,767
it causes convection currents.
295
00:15:26,899 --> 00:15:31,100
The convection currents
pull electric charges around
296
00:15:31,166 --> 00:15:35,042
and cause magnetic fields
to fold in on themselves.
297
00:15:35,066 --> 00:15:38,366
We call this a dynamo,
and this is what's capable
298
00:15:38,466 --> 00:15:40,767
of generating powerful
magnetic fields.
299
00:15:43,165 --> 00:15:47,000
The magnetic field forms
a protective bubble around Earth
300
00:15:47,100 --> 00:15:50,299
that deflects the solar wind
away from our planet.
301
00:15:52,165 --> 00:15:56,643
Did Mars once have
its own force field?
302
00:15:56,667 --> 00:15:58,700
To find out,
303
00:15:58,767 --> 00:16:02,100
MAVEN hones in on some
ancient volcanic rocks
304
00:16:02,166 --> 00:16:03,866
on the Martian surface.
305
00:16:05,667 --> 00:16:08,700
It detects faint
magnetic traces.
306
00:16:11,799 --> 00:16:12,424
Martian rocks,
typically in the form of lava,
307
00:16:12,448 --> 00:16:14,342
Martian rocks,
typically in the form of lava,
308
00:16:14,366 --> 00:16:17,500
become magnetic
when the iron particles
309
00:16:17,567 --> 00:16:20,466
in the rocks become aligned
with the magnetic field
310
00:16:20,567 --> 00:16:23,299
that's active at the time,
and then as the rock cools,
311
00:16:23,366 --> 00:16:25,000
those things
get frozen in place.
312
00:16:25,066 --> 00:16:27,500
That sort of freezes
a magnetic field into place.
313
00:16:27,567 --> 00:16:31,643
What that tells us,
that these volcanic materials
314
00:16:31,667 --> 00:16:32,799
were erupted at a time
315
00:16:32,866 --> 00:16:35,066
where there was a magnetic
field present on Mars.
316
00:16:37,200 --> 00:16:41,000
Dating the magnetized
rocks reveals that Mars had
317
00:16:41,100 --> 00:16:42,423
an active magnetic field for
almost a billion years.
318
00:16:42,447 --> 00:16:45,066
An active magnetic field for
almost a billion years.
319
00:16:47,265 --> 00:16:50,265
This means
that the atmosphere of
320
00:16:50,366 --> 00:16:54,100
Mars was protected
for those billion years,
321
00:16:54,165 --> 00:16:56,100
and if the atmosphere
was protected,
322
00:16:56,165 --> 00:16:58,000
the liquid water was protected.
323
00:16:58,066 --> 00:17:00,543
And if that liquid water was
a home for life,
324
00:17:00,567 --> 00:17:02,667
then that life was protected.
325
00:17:04,866 --> 00:17:08,799
But something happened to
bring Mars's force field down.
326
00:17:11,366 --> 00:17:12,423
To discover what, our quake
specialist, Insight, is ready to
327
00:17:12,448 --> 00:17:16,000
To discover what, our quake
specialist, Insight, is ready to
328
00:17:16,099 --> 00:17:19,299
burst open the mystery of
the planet's lost
329
00:17:19,366 --> 00:17:20,567
protective shield.
330
00:17:31,366 --> 00:17:34,366
Robots are rewriting
the history of Mars.
331
00:17:35,767 --> 00:17:38,241
They found that Mars once had
332
00:17:38,266 --> 00:17:41,366
a magnetic field that
protected its atmosphere.
333
00:17:43,099 --> 00:17:45,767
Now, another team member,
Insight,
334
00:17:45,866 --> 00:17:47,767
probes the planet's interior.
335
00:17:48,900 --> 00:17:51,843
Its mission...
To discover if the secret of
336
00:17:51,866 --> 00:17:53,151
the planet's lost magnetic
field lies
337
00:17:53,174 --> 00:17:55,041
the planet's lost magnetic
field lies
338
00:17:55,066 --> 00:17:57,799
beneath the Martian surface.
339
00:17:57,866 --> 00:18:00,900
Insight was developed with
the world's best seismometer.
340
00:18:01,000 --> 00:18:03,366
This is a really precise,
really delicate,
341
00:18:03,467 --> 00:18:05,866
really sensitive instrument,
and it just was placed on
342
00:18:05,967 --> 00:18:07,299
the surface
and started listening.
343
00:18:09,567 --> 00:18:10,799
2021.
344
00:18:11,866 --> 00:18:16,900
Insight listens for seismic
vibrations, called Mars quakes,
345
00:18:17,000 --> 00:18:19,666
as they travel through
the planet's interior.
346
00:18:19,767 --> 00:18:22,366
It's detected
quite a few Mars quakes,
347
00:18:22,467 --> 00:18:23,151
but these were very small,
348
00:18:23,174 --> 00:18:24,000
but these were very small,
349
00:18:24,066 --> 00:18:26,900
but then it detected
two much larger ones.
350
00:18:31,066 --> 00:18:32,200
And these were interesting.
351
00:18:32,266 --> 00:18:34,742
Not only were they more
powerful, but they were coming
352
00:18:34,767 --> 00:18:37,241
from the direction of
Cerberus Fossae,
353
00:18:37,266 --> 00:18:39,500
which is a very interesting
region on Mars.
354
00:18:40,666 --> 00:18:44,343
The magnitude 3.1 and 3.3 quakes
355
00:18:44,366 --> 00:18:46,643
came from Cerberus Fossae,
356
00:18:46,666 --> 00:18:51,542
a series of trenches that
stretched for 750 miles across
357
00:18:51,567 --> 00:18:53,151
the Martian surface.
358
00:18:53,174 --> 00:18:53,200
The Martian surface.
359
00:18:53,266 --> 00:18:56,799
Some fissures cut through
impact craters that
360
00:18:56,866 --> 00:18:58,767
are only a few million
years old.
361
00:19:00,299 --> 00:19:03,000
This means Cerberus Fossae
362
00:19:03,099 --> 00:19:04,567
must be younger.
363
00:19:07,567 --> 00:19:10,799
Insight teams up with
the Mars Reconnaissance Orbiter,
364
00:19:10,866 --> 00:19:14,000
flying hundreds of miles above.
365
00:19:14,099 --> 00:19:15,942
This eye in the sky
366
00:19:15,967 --> 00:19:18,400
spots an ancient lava flow,
367
00:19:18,467 --> 00:19:21,000
spreading out
over a three mile area.
368
00:19:21,066 --> 00:19:23,151
Dating of the flow
reveals that it's recent.
369
00:19:23,174 --> 00:19:25,099
Dating of the flow
reveals that it's recent.
370
00:19:26,599 --> 00:19:28,767
The Mars Reconnaissance Orbiter
spotted,
371
00:19:28,866 --> 00:19:30,666
in the Cerberus Fossae region,
372
00:19:30,767 --> 00:19:35,165
some lavas that appear to be
about 50,000 years old.
373
00:19:35,266 --> 00:19:37,500
This is crazy young for Mars.
374
00:19:37,567 --> 00:19:40,500
Mars has been around
for billions of years.
375
00:19:40,567 --> 00:19:42,643
50,000 years is nothing.
376
00:19:42,666 --> 00:19:45,041
Humans were around on Earth
that long ago.
377
00:19:45,066 --> 00:19:47,000
So this is really recent.
378
00:19:47,099 --> 00:19:50,099
Based on the fact that we had
379
00:19:50,165 --> 00:19:53,151
these two Mars quakes recently,
plus the evidence of
380
00:19:53,174 --> 00:19:53,500
these two Mars quakes recently,
plus the evidence of
381
00:19:53,567 --> 00:19:56,041
the volcanic eruption
just 50,000 years ago,
382
00:19:56,066 --> 00:19:59,542
I mean, now we cannot
say that Mars is dead.
383
00:19:59,567 --> 00:20:02,666
We have to say Mars is active.
384
00:20:02,767 --> 00:20:05,700
A volcanically active Mars
385
00:20:05,767 --> 00:20:10,400
suggests its interior may
still be warm... if it is,
386
00:20:10,467 --> 00:20:14,343
why did the planet's
magnetic field die?
387
00:20:14,366 --> 00:20:17,942
Insight probes
deep into the interior of
388
00:20:17,967 --> 00:20:22,567
the Red Planet using vibrations
from small Mars quakes.
389
00:20:24,099 --> 00:20:26,942
Insight uses these to kind of
construct what the interior of
390
00:20:26,967 --> 00:20:28,266
Mars was like,
391
00:20:28,366 --> 00:20:30,866
because these waves
bounce off different layers
392
00:20:30,967 --> 00:20:33,366
inside the interior of Mars
in different ways.
393
00:20:34,467 --> 00:20:38,165
Insight's seismometer
builds a picture of Mars
394
00:20:38,266 --> 00:20:42,366
by completely redrawing the map
of the interior of the planet.
395
00:20:44,165 --> 00:20:45,700
It turns out
the crust is thinner
396
00:20:45,767 --> 00:20:49,900
than we thought...
It's only 12 to 23 miles thick.
397
00:20:50,000 --> 00:20:53,151
So there's this whole picture
of Mars that is unfolding in
398
00:20:53,174 --> 00:20:53,767
So there's this whole picture
of Mars that is unfolding in
399
00:20:53,866 --> 00:20:55,767
front of us that is
vastly different
400
00:20:55,866 --> 00:20:57,266
than we ever predicted.
401
00:20:58,567 --> 00:21:02,099
Insight's new and improved
layout of Mars reveals
402
00:21:02,165 --> 00:21:08,467
a 969-mile-deep mantle
surrounding a metal-rich core.
403
00:21:10,200 --> 00:21:13,500
New analysis of data from
Insight reveals the size of
404
00:21:13,567 --> 00:21:15,599
the core of Mars,
and we haven't had this before.
405
00:21:15,666 --> 00:21:16,567
It's so exciting.
406
00:21:16,666 --> 00:21:19,767
It's about 1,100 miles
in radius.
407
00:21:19,866 --> 00:21:22,343
This is a little more than
half the radius of the body,
408
00:21:22,366 --> 00:21:23,152
which is pretty big, and is
much bigger than we expected
409
00:21:23,175 --> 00:21:25,400
which is pretty big, and is
much bigger than we expected
410
00:21:25,467 --> 00:21:27,767
for the size
of the core of Mars.
411
00:21:28,900 --> 00:21:30,767
Mars's larger core
412
00:21:30,866 --> 00:21:33,866
makes up about a quarter
of the planet's mass.
413
00:21:33,967 --> 00:21:35,567
And Insight's journey to
414
00:21:35,666 --> 00:21:39,000
the center of Mars
reveals another surprise.
415
00:21:40,165 --> 00:21:42,142
We have always thought
that the core of Mars
416
00:21:42,165 --> 00:21:45,942
was long since solidified
and wasn't warm at all.
417
00:21:45,967 --> 00:21:48,599
And Insight is now showing us
that actually,
418
00:21:48,666 --> 00:21:51,442
part of the core is probably
still molten,
419
00:21:51,467 --> 00:21:52,666
which is shocking.
420
00:21:54,767 --> 00:21:57,599
There's a liquid core at Mars.
I mean, this is crazy.
421
00:22:00,467 --> 00:22:02,700
Data from past missions may help
422
00:22:02,767 --> 00:22:06,900
explain why Mars's core
is still liquid.
423
00:22:07,000 --> 00:22:11,266
Scientists discovered high
levels of sulfur in the crust.
424
00:22:12,500 --> 00:22:14,266
Mars seems to have
a bit more sulfur,
425
00:22:14,366 --> 00:22:16,241
at least in the surface,
than Earth does.
426
00:22:16,266 --> 00:22:18,767
If we extend that composition
to the core
427
00:22:18,866 --> 00:22:21,643
and add more sulfur to
the iron-nickel core,
428
00:22:21,666 --> 00:22:23,151
that would actually reduce
its melting temperature,
429
00:22:23,174 --> 00:22:24,343
that would actually reduce
its melting temperature,
430
00:22:24,366 --> 00:22:29,165
making it possible for this
core to be molten today.
431
00:22:30,500 --> 00:22:33,343
We thought that Mars
lost its magnetic field
432
00:22:33,366 --> 00:22:36,643
when the core
cooled and solidified.
433
00:22:36,666 --> 00:22:39,366
A molten core
changes everything.
434
00:22:40,400 --> 00:22:42,843
Well, how can we explain
this lack of a magnetic field
435
00:22:42,866 --> 00:22:45,299
at Mars even though
there's a liquid core?
436
00:22:45,366 --> 00:22:47,099
Well, in order to have
a magnetic field,
437
00:22:47,165 --> 00:22:50,400
you need the fluid to be moving
and rotating and convecting.
438
00:22:51,967 --> 00:22:53,151
Over time, as Mars
lost heat and cooled down
439
00:22:53,174 --> 00:22:55,542
Over time, as Mars
lost heat and cooled down
440
00:22:55,567 --> 00:22:59,366
its core stayed molten
thanks to the sulfur.
441
00:22:59,467 --> 00:23:02,099
But, with less heat,
there was not enough
442
00:23:02,165 --> 00:23:05,799
energy to power the churning
convection of liquid metal
443
00:23:05,866 --> 00:23:08,767
that creates
an electric current.
444
00:23:08,866 --> 00:23:11,700
The convection in that core
would have slowed down
445
00:23:11,767 --> 00:23:14,266
to the point where no magnetic
field would be generated.
446
00:23:17,000 --> 00:23:22,000
3.7 billion years ago,
Mars's magnetic shield dies.
447
00:23:23,400 --> 00:23:25,742
The solar wind's
relentless attack
448
00:23:25,767 --> 00:23:28,843
strips the planet of
its atmosphere.
449
00:23:28,866 --> 00:23:31,467
As the atmosphere disappears,
450
00:23:31,567 --> 00:23:35,967
water on the surface
gradually boils away.
451
00:23:39,799 --> 00:23:43,165
But did all of the planet's
water dissipate?
452
00:23:44,366 --> 00:23:49,165
To find out,
our robots once again team up.
453
00:23:58,967 --> 00:24:03,000
Since the first probe
visited Mars in 1971,
454
00:24:03,099 --> 00:24:06,700
16 missions have investigated
the Red Planet from orbit,
455
00:24:08,266 --> 00:24:11,467
while 10 landers
have explored the surface.
456
00:24:12,700 --> 00:24:16,767
They've revealed Mars may
still be an active planet,
457
00:24:16,866 --> 00:24:20,500
one that once had the right
conditions for life.
458
00:24:21,866 --> 00:24:24,241
Mars used to be
thought of as this dry,
459
00:24:24,266 --> 00:24:26,542
arid, inhospitable environment.
460
00:24:26,567 --> 00:24:28,843
And thanks to the recent
Mars missions,
461
00:24:28,866 --> 00:24:32,200
we know now that they could
have sustained life.
462
00:24:33,866 --> 00:24:36,200
Could there be any
ancient Martian
463
00:24:36,266 --> 00:24:39,567
water left,
hidden inside the planet today?
464
00:24:39,666 --> 00:24:44,266
MAVEN investigates by
analyzing Mars's atmosphere
465
00:24:44,366 --> 00:24:47,942
for one of water's
components... hydrogen.
466
00:24:47,967 --> 00:24:49,799
The MAVEN mission is looking at
467
00:24:49,866 --> 00:24:51,506
hydrogen that's currently in
the Mars atmosphere.
468
00:24:51,529 --> 00:24:52,542
Hydrogen that's currently in
the Mars atmosphere.
469
00:24:52,567 --> 00:24:55,366
This is a really important
thing to study.
470
00:24:57,165 --> 00:25:00,866
The gas is produced when
the solar wind slams into Mars's
471
00:25:00,967 --> 00:25:03,567
thin atmosphere
and smashes apart
472
00:25:03,666 --> 00:25:07,066
molecules of water
into hydrogen and oxygen.
473
00:25:08,366 --> 00:25:11,241
Hydrogen molecules
come in two forms...
474
00:25:11,266 --> 00:25:15,400
Light, regular hydrogen
and the heavier deuterium.
475
00:25:16,666 --> 00:25:18,942
The ratio of the different types
476
00:25:18,967 --> 00:25:21,506
tells us about the history of
water on the Red Planet.
477
00:25:21,529 --> 00:25:22,742
Tells us about the history of
water on the Red Planet.
478
00:25:22,767 --> 00:25:26,942
It turns out that it's much
easier to lose the lighter
479
00:25:26,967 --> 00:25:28,500
version, because gravity
480
00:25:28,567 --> 00:25:30,942
just you can't hold on to
something that's light as
481
00:25:30,967 --> 00:25:32,299
easily as a heavier thing.
482
00:25:32,366 --> 00:25:34,843
So we expect that,
as time goes on,
483
00:25:34,866 --> 00:25:37,200
we'll have less and less
light hydrogen
484
00:25:37,266 --> 00:25:38,700
and more and more
heavy hydrogen.
485
00:25:39,866 --> 00:25:43,567
So if we can measure
the outflow of hydrogen from
486
00:25:43,666 --> 00:25:46,000
the Martian atmosphere today,
487
00:25:46,066 --> 00:25:49,942
and specifically, whether
it's light or heavy hydrogen,
488
00:25:49,967 --> 00:25:51,506
we can start to get some kind
of idea about how much water
489
00:25:51,529 --> 00:25:53,942
we can start to get some kind
of idea about how much water
490
00:25:53,967 --> 00:25:55,942
has been lost from Mars
491
00:25:55,967 --> 00:25:58,467
and therefore how much might
still be there today.
492
00:26:00,266 --> 00:26:03,599
2021... scientists at Caltech
493
00:26:03,666 --> 00:26:07,142
analyze data from Mars's
rovers and orbiters
494
00:26:07,165 --> 00:26:09,599
to discover the ratio of
495
00:26:09,666 --> 00:26:12,241
deuterium to hydrogen
in the atmosphere.
496
00:26:12,266 --> 00:26:16,843
They find less of the heavy
hydrogen than expected.
497
00:26:16,866 --> 00:26:20,767
If Mars had lost a lot of
its original water
498
00:26:20,866 --> 00:26:21,507
out into outer space,
499
00:26:21,530 --> 00:26:23,400
out into outer space,
500
00:26:23,467 --> 00:26:27,165
we'd expect to find lots of
heavy hydrogen
501
00:26:27,266 --> 00:26:30,266
left behind in the atmosphere.
502
00:26:30,366 --> 00:26:33,165
But, in fact, what we found
was that the ratio
503
00:26:33,266 --> 00:26:38,400
told us that Mars didn't lose
much of its water upwards.
504
00:26:39,467 --> 00:26:42,165
And so maybe
the water went downwards.
505
00:26:42,266 --> 00:26:46,343
Where is Mars's water hiding?
506
00:26:46,366 --> 00:26:48,567
Some scientists
think it could be
507
00:26:48,666 --> 00:26:51,506
stashed away
in the Martian rocks.
508
00:26:51,529 --> 00:26:51,743
Stashed away
in the Martian rocks.
509
00:26:51,768 --> 00:26:54,666
When we look at a rock,
we often think this is a really
510
00:26:54,767 --> 00:26:56,866
dry thing,
there's no water in there.
511
00:26:56,967 --> 00:26:59,767
But, in fact,
there's often a lot of water
512
00:26:59,866 --> 00:27:03,700
in rocks, and it's because
it's bound up in minerals.
513
00:27:03,767 --> 00:27:06,266
Changes in the crust can drive
514
00:27:06,366 --> 00:27:07,942
these minerals to suck up huge
515
00:27:07,967 --> 00:27:11,700
volumes of water,
equivalent to a global layer
516
00:27:11,767 --> 00:27:13,165
over 300 feet deep.
517
00:27:14,165 --> 00:27:17,643
Researchers estimate
that as much as 99 percent of
518
00:27:17,666 --> 00:27:21,506
Mars's water could be locked
away below the surface.
519
00:27:21,529 --> 00:27:23,375
Mars's water could be locked
away below the surface.
520
00:27:23,400 --> 00:27:26,500
And Mars hides water
in other ways, too.
521
00:27:26,567 --> 00:27:29,843
Enter the European
Space Agency's orbiter,
522
00:27:29,866 --> 00:27:33,000
Mars Express... probing one mile
523
00:27:33,066 --> 00:27:35,000
beneath the Martian South Pole,
524
00:27:35,099 --> 00:27:39,266
it finds a secret store
of water.
525
00:27:39,366 --> 00:27:44,000
Really exciting.
We've discovered a system of
526
00:27:44,066 --> 00:27:48,542
lakes beneath the Martian
polar ice caps,
527
00:27:48,567 --> 00:27:51,506
lakes of what appears
to be liquid water.
528
00:27:51,529 --> 00:27:53,130
Lakes of what appears
to be liquid water.
529
00:27:53,700 --> 00:27:55,742
Now, these lakes
are not very deep.
530
00:27:55,767 --> 00:27:57,343
They're probably only
a couple of feet deep,
531
00:27:57,366 --> 00:27:59,700
maybe in some places even
a couple of inches deep,
532
00:27:59,767 --> 00:28:01,000
but they're quite large.
533
00:28:01,066 --> 00:28:03,542
Some of these are
about 20 miles across.
534
00:28:03,567 --> 00:28:05,900
And there's even some
suggestion that these are
535
00:28:06,000 --> 00:28:09,366
connected with channels, kind of
a system of very shallow
536
00:28:09,467 --> 00:28:11,165
great lakes near
the South Pole of Mars.
537
00:28:11,266 --> 00:28:14,767
The Martian poles are
538
00:28:14,866 --> 00:28:17,241
the coldest regions
on the planet.
539
00:28:17,266 --> 00:28:21,500
Temperatures can
reach 200 degrees below zero.
540
00:28:21,567 --> 00:28:24,900
So why is it that
underneath this cold ice,
541
00:28:25,000 --> 00:28:26,900
you might even find
liquid water?
542
00:28:27,000 --> 00:28:28,643
Well, remember,
you're actually going down
543
00:28:28,666 --> 00:28:30,643
closer into the interior
544
00:28:30,666 --> 00:28:33,000
of Mars there,
and so that's warm.
545
00:28:33,066 --> 00:28:35,442
It's possible that
the geologic activity inside
546
00:28:35,467 --> 00:28:38,400
Mars is warming the ice
from the underneath.
547
00:28:39,866 --> 00:28:42,442
But heat from
the interior of Mars
548
00:28:42,467 --> 00:28:46,366
wouldn't be enough to keep
these lakes liquid.
549
00:28:46,467 --> 00:28:49,400
The secret ingredient
may be salt.
550
00:28:50,500 --> 00:28:51,506
If you've ever spread
salt on an icy driveway,
551
00:28:51,529 --> 00:28:53,329
If you've ever spread
salt on an icy driveway,
552
00:28:53,366 --> 00:28:55,567
you'll notice that where
the salt hits the driveway,
553
00:28:55,666 --> 00:28:57,241
the ice begins to melt.
554
00:28:57,266 --> 00:28:59,799
Saltwater actually freezes at
555
00:28:59,866 --> 00:29:02,942
a much lower temperature
than water that's fresh.
556
00:29:02,967 --> 00:29:04,400
So if it's salty water,
557
00:29:04,467 --> 00:29:07,542
it could actually stay liquid
at lower temperatures.
558
00:29:07,567 --> 00:29:10,866
We still aren't
100 percent sure that the lakes
559
00:29:10,967 --> 00:29:12,299
are completely liquid.
560
00:29:12,366 --> 00:29:16,442
Some scientists think they
could be lakes of frozen clay.
561
00:29:16,467 --> 00:29:20,599
Until we have a rover that can
explore beneath the poles,
562
00:29:20,666 --> 00:29:21,506
we won't know for sure.
563
00:29:21,529 --> 00:29:22,529
We won't know for sure.
564
00:29:24,767 --> 00:29:27,767
The only real way we can tell
for sure is to send
565
00:29:27,866 --> 00:29:29,142
some kind of mission that drills
566
00:29:29,165 --> 00:29:33,041
right down through
that polar ice and samples
567
00:29:33,066 --> 00:29:34,866
what we find at the bottom.
568
00:29:34,967 --> 00:29:37,500
Wherever it may be hiding,
569
00:29:37,567 --> 00:29:40,700
Mars's water is locked away,
570
00:29:40,767 --> 00:29:45,799
but in its past, the planet had
impressive lakes and rivers.
571
00:29:45,866 --> 00:29:48,099
Did they ever host life?
572
00:29:48,165 --> 00:29:50,767
To find out, the rovers
573
00:29:50,866 --> 00:29:51,507
take a deep dive into Mars.
574
00:29:51,530 --> 00:29:53,567
Take a deep dive into Mars.
575
00:30:07,666 --> 00:30:11,900
Veteran crew member, Curiosity,
explores the Gale Crater.
576
00:30:13,000 --> 00:30:15,299
The rover's mission?
To find evidence
577
00:30:15,366 --> 00:30:18,500
of whether Mars could have
supported life.
578
00:30:20,866 --> 00:30:23,643
Los Alamos National Laboratory.
579
00:30:23,666 --> 00:30:25,942
Principal investigator
of Curiosity's
580
00:30:25,967 --> 00:30:26,904
ChemCam, Nina Lanza,
works closely with the rover
581
00:30:26,929 --> 00:30:29,666
ChemCam, Nina Lanza,
works closely with the rover
582
00:30:29,767 --> 00:30:34,099
patrolling Mars 34 million
miles away.
583
00:30:34,165 --> 00:30:37,542
In many ways, Curiosity
is like my first child.
584
00:30:37,567 --> 00:30:40,099
We had to take such good care
of her while she was still here
585
00:30:40,165 --> 00:30:43,599
on Earth, but like all children,
she had to forge her own path.
586
00:30:43,666 --> 00:30:45,742
And so we had to send her
on her way
587
00:30:45,767 --> 00:30:48,567
to discover new things
on Mars by herself.
588
00:30:53,767 --> 00:30:56,343
ChemCam uses
a precision laser that
589
00:30:56,366 --> 00:30:56,904
analyzes the chemical
composition of Martian rocks.
590
00:30:56,929 --> 00:31:01,142
Analyzes the chemical
composition of Martian rocks.
591
00:31:01,165 --> 00:31:04,599
We have a laser that
we focus onto a target
592
00:31:04,666 --> 00:31:09,299
up to 23 feet away, and we
vaporize a little material,
593
00:31:09,366 --> 00:31:10,843
and then we look at the light
594
00:31:10,866 --> 00:31:13,041
made by this vaporized material
and figure out
595
00:31:13,066 --> 00:31:14,299
what elements are in the rock.
596
00:31:15,467 --> 00:31:18,000
Working with an instrument
like ChemCam is really
597
00:31:18,099 --> 00:31:21,099
a childhood dream come true,
because I was always hoping
598
00:31:21,165 --> 00:31:23,099
to work on a spaceship,
and today, I work on
599
00:31:23,165 --> 00:31:25,142
a spaceship with lasers.
600
00:31:25,165 --> 00:31:26,500
How cool is that?
601
00:31:28,467 --> 00:31:30,366
With their
long-distance teamwork, Nina
602
00:31:30,467 --> 00:31:34,366
and Curiosity discover rocks
with a shiny coating,
603
00:31:34,467 --> 00:31:37,165
laced with manganese.
604
00:31:37,266 --> 00:31:40,000
One of the most exciting
discoveries from Curiosity in
605
00:31:40,066 --> 00:31:42,866
Gale Crater was the existence
of high concentrations
606
00:31:42,967 --> 00:31:46,142
of an element called manganese,
and that's because manganese on
607
00:31:46,165 --> 00:31:49,066
Earth is very closely tied
to life.
608
00:31:50,799 --> 00:31:54,165
Could the manganese of Mars
be linked to life forms?
609
00:31:55,200 --> 00:31:56,903
To investigate, scientists
look at similar coatings
610
00:31:56,927 --> 00:31:58,442
To investigate, scientists
look at similar coatings
611
00:31:58,467 --> 00:32:02,799
called varnish on desert rocks
here on Earth.
612
00:32:02,866 --> 00:32:05,643
So I have an example here
of some rock varnish,
613
00:32:05,666 --> 00:32:09,000
and you can see,
it's actually incredibly dark.
614
00:32:09,099 --> 00:32:10,567
It has a lot of iron oxide,
615
00:32:10,666 --> 00:32:13,000
manganese oxide,
and clay minerals in them.
616
00:32:13,099 --> 00:32:14,442
And the rocks can sometimes have
617
00:32:14,467 --> 00:32:16,666
none of these things
in the rock itself.
618
00:32:17,866 --> 00:32:20,799
So the question is, where does
this coating come from?
619
00:32:20,866 --> 00:32:23,900
Often,
we find microbes associated
620
00:32:24,000 --> 00:32:26,142
with the varnishes
and so possibly,
621
00:32:26,165 --> 00:32:26,904
these microbes
actually helped fix
622
00:32:26,929 --> 00:32:28,467
these microbes
actually helped fix
623
00:32:28,567 --> 00:32:30,299
the manganese onto the surface.
624
00:32:32,066 --> 00:32:35,000
The age of these Earth
varnishes may provide
625
00:32:35,099 --> 00:32:38,866
a clue to Mars's
distant past... here,
626
00:32:38,967 --> 00:32:42,142
they only appear after
a significant event in
627
00:32:42,165 --> 00:32:43,343
our history...
628
00:32:43,366 --> 00:32:46,567
The creation of
the oxygen we breathe.
629
00:32:47,599 --> 00:32:48,866
A couple of billion years ago
630
00:32:48,967 --> 00:32:51,666
on Earth was the great
oxygenation event.
631
00:32:53,700 --> 00:32:55,767
Basically, the Earth's
atmosphere did not have
632
00:32:55,866 --> 00:32:56,903
a lot of oxygen in it.
633
00:32:56,927 --> 00:32:57,000
A lot of oxygen in it.
634
00:32:57,066 --> 00:32:58,767
It was locked up in
minerals and chemicals.
635
00:33:00,066 --> 00:33:03,567
Well, some bacteria discovered
how to photosynthesize light,
636
00:33:03,666 --> 00:33:06,467
how to convert energy from
light into their metabolism.
637
00:33:06,567 --> 00:33:10,500
And via the chemistry of this,
they wound up emitting oxygen.
638
00:33:13,767 --> 00:33:16,767
The oxygen was poison
to many life forms,
639
00:33:16,866 --> 00:33:19,299
so they died out.
640
00:33:19,366 --> 00:33:21,567
But others thrived, pumping more
641
00:33:21,666 --> 00:33:24,500
and more oxygen
into the atmosphere.
642
00:33:24,567 --> 00:33:26,903
Oxygen reacts with
the manganese,
643
00:33:26,928 --> 00:33:27,143
Oxygen reacts with
the manganese,
644
00:33:27,166 --> 00:33:28,599
binding it to the rocks.
645
00:33:31,366 --> 00:33:33,266
We don't really see
these minerals until
646
00:33:33,366 --> 00:33:35,442
after the rise of oxygen
in the atmosphere,
647
00:33:35,467 --> 00:33:37,299
so after photosynthesis.
648
00:33:38,767 --> 00:33:43,000
For Mars to have
these same manganese varnishes,
649
00:33:43,099 --> 00:33:45,500
there must have once been
more oxygen
650
00:33:45,567 --> 00:33:47,643
in the planet's atmosphere.
651
00:33:47,666 --> 00:33:49,442
Is it possible
that Mars had a lot
652
00:33:49,467 --> 00:33:52,142
of oxygen in its atmosphere
in the past,
653
00:33:52,165 --> 00:33:54,467
and there were wee little
beasties processing it?
654
00:33:56,500 --> 00:33:56,904
And so the search
continues, and Curiosity uses
655
00:33:56,929 --> 00:34:00,099
And so the search
continues, and Curiosity uses
656
00:34:00,165 --> 00:34:01,866
another piece of equipment
657
00:34:01,967 --> 00:34:05,843
to sniff out
traces of past Martian life.
658
00:34:05,866 --> 00:34:10,300
One of the key instruments
aboard Curiosity is a piece of
659
00:34:10,367 --> 00:34:12,443
lab kit called a gas
660
00:34:12,467 --> 00:34:15,000
chromatography
mass spectrometer,
661
00:34:15,099 --> 00:34:19,599
or GC-MS, and all this really
is, in essence, is, like,
662
00:34:19,666 --> 00:34:22,666
a very sensitive
electronic nose.
663
00:34:25,000 --> 00:34:26,903
Curiosity digs up some
Martian soil
664
00:34:26,927 --> 00:34:28,041
Curiosity digs up some
Martian soil
665
00:34:28,065 --> 00:34:30,567
and heats it
in its portable chem lab.
666
00:34:33,166 --> 00:34:34,867
Like a robotic bloodhound,
667
00:34:34,967 --> 00:34:38,099
it sniffs the vaporized dirt
and picks up
668
00:34:38,166 --> 00:34:41,567
the faint smell of
a rare molecular compound.
669
00:34:43,567 --> 00:34:47,842
What Curiosity discovered was
a compound called thiophene.
670
00:34:47,867 --> 00:34:50,166
This is interesting,
because at least on Earth,
671
00:34:50,266 --> 00:34:52,099
thiophene is often found
672
00:34:52,166 --> 00:34:55,567
in fossil material, in coal,
673
00:34:55,666 --> 00:34:56,903
in oil, as well as
stromatolites or micro fossils
674
00:34:56,927 --> 00:34:59,766
in oil, as well as
stromatolites or micro fossils
675
00:34:59,867 --> 00:35:02,099
of ancient life
in the fossil record.
676
00:35:03,699 --> 00:35:06,300
So maybe this thiophene
we've now discovered on
677
00:35:06,367 --> 00:35:12,867
Mars is some trace chemical
fossil of ancient Martian life.
678
00:35:14,300 --> 00:35:18,567
Or possibly, it was produced
by non-biological processes.
679
00:35:23,900 --> 00:35:25,867
Curiosity is knocking
on the door
680
00:35:25,967 --> 00:35:26,903
of finding the evidence
for life on Mars.
681
00:35:26,927 --> 00:35:28,527
Of finding the evidence
for life on Mars.
682
00:35:29,166 --> 00:35:31,867
We haven't found life,
but we've found the interesting
683
00:35:31,967 --> 00:35:34,266
bits that are pieces of
the puzzle,
684
00:35:34,367 --> 00:35:36,443
the organic puzzle of life
on Mars.
685
00:35:36,467 --> 00:35:39,800
And so it's getting us to that
ultimate question, is there
686
00:35:39,867 --> 00:35:41,567
or was there ever life
on the planet?
687
00:35:44,000 --> 00:35:45,443
To help answer that question,
688
00:35:45,467 --> 00:35:48,300
scientists bring in
pinch hitter, Perseverance.
689
00:35:48,367 --> 00:35:49,666
The newest member of the crew
690
00:35:49,766 --> 00:35:53,141
has the latest tech, tools
designed based on lessons from
691
00:35:53,166 --> 00:35:54,400
previous missions.
692
00:35:57,099 --> 00:36:00,467
Perseverance is so important,
because it leverages all of
693
00:36:00,567 --> 00:36:04,099
the knowledge of the previous
rovers, which set the stage for
694
00:36:04,166 --> 00:36:06,567
taking samples
on the surface of Mars,
695
00:36:06,666 --> 00:36:09,500
searching for life, and setting
up a place for humans to
696
00:36:09,567 --> 00:36:10,666
explore in the future.
697
00:36:13,300 --> 00:36:16,467
Perseverance gathers
rock and soil samples,
698
00:36:16,567 --> 00:36:20,599
testing some itself and leaving
others to be collected
699
00:36:20,666 --> 00:36:23,099
and returned to Earth later.
700
00:36:23,166 --> 00:36:25,367
We are just at the beginning of
701
00:36:25,467 --> 00:36:26,500
the Perseverance mission.
702
00:36:26,567 --> 00:36:26,905
We have so much to learn.
703
00:36:26,929 --> 00:36:29,199
We have so much to learn.
704
00:36:29,266 --> 00:36:32,000
But I think all of us
would be so thrilled
705
00:36:32,099 --> 00:36:35,300
if we could actually find
definitive signs of past
706
00:36:35,367 --> 00:36:37,000
Martian life...
That would be incredible.
707
00:36:37,099 --> 00:36:39,467
I don't know what form
that would take,
708
00:36:39,567 --> 00:36:42,666
but we're going to look for it
in every way that we know how.
709
00:36:44,867 --> 00:36:47,199
While Perseverance
hunts for evidence
710
00:36:47,266 --> 00:36:48,467
of ancient life on Mars,
711
00:36:51,300 --> 00:36:54,400
Curiosity detects
hints that life may
712
00:36:54,467 --> 00:36:56,903
exist on the Red Planet now.
713
00:36:56,927 --> 00:36:58,047
Exist on the Red Planet now.
714
00:37:10,166 --> 00:37:12,867
In Gale Crater,
Curiosity detects
715
00:37:12,967 --> 00:37:14,967
a huge surge of methane gas.
716
00:37:16,599 --> 00:37:19,266
The methane we've
detected in the atmosphere of
717
00:37:19,367 --> 00:37:21,967
Mars is potentially very,
very exciting.
718
00:37:23,300 --> 00:37:25,467
Most of the methane
in our own air,
719
00:37:25,567 --> 00:37:28,000
in Earth's atmosphere,
is biogenic.
720
00:37:28,065 --> 00:37:30,467
It was released
by living organisms.
721
00:37:31,900 --> 00:37:35,000
Curiosity's result
is exciting, because we know
722
00:37:35,099 --> 00:37:37,367
that this can't be
ancient methane.
723
00:37:38,666 --> 00:37:41,000
Methane is really interesting,
because it has a short
724
00:37:41,099 --> 00:37:42,842
residency time in an atmosphere,
725
00:37:42,867 --> 00:37:45,867
which means it breaks down
very quickly.
726
00:37:45,967 --> 00:37:48,766
Whatever is making methane
in Gale Crater
727
00:37:48,867 --> 00:37:50,300
is doing it right now.
728
00:37:53,766 --> 00:37:57,266
Curiosity has detected
methane many times before.
729
00:37:57,367 --> 00:38:00,041
But this is the largest
amount so far.
730
00:38:00,065 --> 00:38:00,561
The question is,
what created it?
731
00:38:00,585 --> 00:38:03,467
The question is,
what created it?
732
00:38:04,867 --> 00:38:07,000
Maybe this Martian methane is
733
00:38:07,099 --> 00:38:11,666
the first trace we found of
Martian life,
734
00:38:11,766 --> 00:38:14,367
micro organisms living
deep underground.
735
00:38:16,800 --> 00:38:21,467
Or maybe that methane is
not biological, but geological.
736
00:38:21,567 --> 00:38:25,300
It's methane that's been given
off by volcanic processes in
737
00:38:25,367 --> 00:38:26,543
the past.
738
00:38:26,567 --> 00:38:29,300
The frustration is,
we can't quite tell
739
00:38:29,367 --> 00:38:30,561
the difference
between the two just yet.
740
00:38:30,585 --> 00:38:31,166
The difference
between the two just yet.
741
00:38:31,266 --> 00:38:33,500
All we can do is continue
to sniff
742
00:38:33,567 --> 00:38:38,500
the air and document
when and where we see it.
743
00:38:40,266 --> 00:38:43,342
The picture becomes more
intriguing when Curiosity
744
00:38:43,367 --> 00:38:47,199
detects oxygen in greater
quantities than expected.
745
00:38:50,467 --> 00:38:53,900
There's a lot more oxygen on
Mars than we had suspected,
746
00:38:54,000 --> 00:38:55,242
which is weird
in the first place.
747
00:38:55,266 --> 00:39:00,561
And the amount of oxygen
is changing seasonally.
748
00:39:00,585 --> 00:39:02,242
And the amount of oxygen
is changing seasonally.
749
00:39:02,266 --> 00:39:06,141
There's something in or on Mars
750
00:39:06,166 --> 00:39:09,842
that is adding oxygen
to the Martian atmosphere
751
00:39:09,867 --> 00:39:12,400
during the spring and summer
and then taking it away during
752
00:39:12,467 --> 00:39:13,500
the fall and winter.
753
00:39:13,567 --> 00:39:16,567
There is something that is
actively controlling
754
00:39:16,666 --> 00:39:19,500
the amount of oxygen in
the Martian atmosphere.
755
00:39:19,567 --> 00:39:21,000
What is that?
756
00:39:22,300 --> 00:39:26,000
Most of Earth's oxygen
comes from living organisms
757
00:39:26,099 --> 00:39:30,242
photosynthesizing, and it
changes with the seasons.
758
00:39:30,266 --> 00:39:30,561
We have normal,
cyclical, seasonal variations in
759
00:39:30,585 --> 00:39:35,000
We have normal,
cyclical, seasonal variations in
760
00:39:35,065 --> 00:39:38,766
the amount of oxygen here
on Earth because of life.
761
00:39:39,900 --> 00:39:41,599
The most landmass on the Earth
762
00:39:41,666 --> 00:39:44,400
is located in
the Northern Hemisphere.
763
00:39:44,467 --> 00:39:46,599
And so that means that during
northern summer,
764
00:39:46,666 --> 00:39:48,842
most of the oxygen
on Earth is generated.
765
00:39:48,867 --> 00:39:51,567
So there's a peak in oxygen
during the northern summer.
766
00:39:52,867 --> 00:39:55,666
So where is the oxygen
on Mars coming from?
767
00:39:56,867 --> 00:40:00,561
Oxygen is a known result of
life of photosynthesis.
768
00:40:00,585 --> 00:40:02,543
Oxygen is a known result of
life of photosynthesis.
769
00:40:02,567 --> 00:40:03,842
It's a biosignature.
770
00:40:03,867 --> 00:40:05,699
It's a sign of life.
771
00:40:05,766 --> 00:40:08,166
Is this a sign of life on Mars?
772
00:40:09,867 --> 00:40:12,266
The atmospheric
changes in oxygen
773
00:40:12,367 --> 00:40:15,300
and methane are
a fascinating puzzle
774
00:40:15,367 --> 00:40:19,000
and a tantalizing hint of life.
775
00:40:19,065 --> 00:40:21,543
Life on Mars
explaining these changes in
776
00:40:21,567 --> 00:40:24,500
methane and oxygen would be
incredibly interesting.
777
00:40:27,967 --> 00:40:30,041
So it's probably wrong.
778
00:40:30,065 --> 00:40:30,561
The answer is probably more
boring, and not that chemistry
779
00:40:30,585 --> 00:40:33,199
The answer is probably more
boring, and not that chemistry
780
00:40:33,266 --> 00:40:34,443
is boring, but it's...
781
00:40:34,467 --> 00:40:37,342
It's a little less
interesting than life.
782
00:40:37,367 --> 00:40:39,766
We Mars scientists, of course,
are always very excited
783
00:40:39,867 --> 00:40:42,800
about seeing signs of maybe
extent life on Mars,
784
00:40:42,867 --> 00:40:45,699
but we're going to require
really big proof before we feel
785
00:40:45,766 --> 00:40:48,266
truly excited that
we've made this discovery.
786
00:40:50,599 --> 00:40:53,400
The army of robotic
explorers continues
787
00:40:53,467 --> 00:40:55,500
to rewrite the story of Mars,
788
00:40:57,266 --> 00:41:00,467
discovering a once warm,
wet world
789
00:41:00,567 --> 00:41:00,561
with the potential for life.
790
00:41:00,585 --> 00:41:02,166
With the potential for life.
791
00:41:05,099 --> 00:41:07,467
Now, a new generation of robots
792
00:41:07,567 --> 00:41:09,742
led by Perseverance will dig
793
00:41:09,766 --> 00:41:13,643
deeper into the Red Planet's
troubled past
794
00:41:13,666 --> 00:41:14,900
and its frozen present
795
00:41:16,300 --> 00:41:20,400
and maybe hit the mother lode,
life itself.
796
00:41:21,867 --> 00:41:23,367
With every new mission to Mars,
797
00:41:23,467 --> 00:41:26,242
I hope that somebody really is
going to find evidence
798
00:41:26,266 --> 00:41:28,000
that life either existed there
799
00:41:28,065 --> 00:41:30,300
in the past or maybe even
still does now.
800
00:41:31,967 --> 00:41:35,199
And with all of these missions
on many places on this planet,
801
00:41:35,266 --> 00:41:38,943
maybe now is the best time to
actually answer that question.
802
00:41:38,967 --> 00:41:40,400
Whether or not it's likely
803
00:41:40,467 --> 00:41:42,643
that Perseverance finds life
on Mars,
804
00:41:42,666 --> 00:41:45,400
we have set ourselves up
for success, and I am
805
00:41:45,467 --> 00:41:49,766
so hopeful that we get to
finally answer that question,
806
00:41:49,867 --> 00:41:50,867
the big question.
807
00:41:52,000 --> 00:41:53,065
Are we alone?
64765
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