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Narrator: For 13 years,
the cassini spacecraft explored
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astounding worlds --
saturn and its moons.
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We discovered things
we never imagined.
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Plait: All of these strange,
bizarre landscapes --
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geysers erupting out of moons.
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Porco: We were so stunned
by the images.
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I mean, people were just
going around in shock.
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�
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narrator: But cassini started
running out of fuel.
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Scientists at NASA had to decide
what to do next,
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and the answer was actually
pretty spectacular.
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Narrator: Cassini goes where no
spacecraft has gone before --
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a death flight revealing
the deepest secrets of saturn.
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-- Captions by vitac --
www.vitac.com
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captions paid for by
discovery communications
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�
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�
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out beyond Jupiter lies saturn,
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a planet circled
by multiple moons and rings.
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It's like a miniature
solar system.
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Imagine having a mission
with the power, the instruments,
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the capability to explore all
aspects of the saturn system.
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Narrator:
That mission was cassini.
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�
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it would become our eyes
and ears
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in the saturnian system
for over 13 years.
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�
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but by September 2017,
cassini was almost out of fuel.
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Cassini has been
orbiting saturn
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and studying the saturn system
for over a decade.
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End the mission -- we're
going to lose control soon,
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so rather than let it
just go derelict,
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we headed into saturn.
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Go out with a bang.
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Narrator:
The cassini team goes for broke.
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They program the probe to head
straight for the planet.
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How cool is it to sort
of sacrifice
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everything you've got
to sort of learn
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your last bit of information,
and then crash and burn?
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Man:
We are in the atmosphere.
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As cassini was careening
toward its death,
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it still had instruments
that continued to work,
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and as each instrument died,
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there was still a set sending
back data and information.
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Narrator: Cassini wasn't
designed to plunge
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through saturn's atmosphere.
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No one knew how long it
would last before burning up.
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�
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spilker:
I remember sitting in a room
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with my colleagues on cassini
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and watching that radio signal,
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that sharp green peak
that told us cassini
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was still linked
to the earth.
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Howett: We could monitor the
atmosphere as we flew into it,
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and right up until the last,
it was sending back science.
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I was really impressed
by how long cassini lasted
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in the saturn atmosphere.
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I mean, go NASA engineering.
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Narrator:
As cassini plummeted down
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at 77,000 miles an hour,
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it was bombarded
by gas molecules
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in saturn's atmosphere.
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�
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friction started tearing
cassini apart
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as it struggled
to maintain contact.
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�
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spilker:
As the antenna turned away,
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we actually saw
a secondary little peak,
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and we thought, "okay, cassini.
Hang in there. Keep fighting."
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And then just
that green flatline.
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Just heard the signal
from the spacecraft is gone,
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and in the next 45 seconds,
so will be the spacecraft.
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Cassini's heartbeat
was gone,
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and we knew
the mission had ended.
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It just vaporized
in the saturnian atmosphere,
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and so it has become
a part of saturn itself.
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�
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�
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narrator:
Cassini's death plunge
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was the last of a series
of daring dives.
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Oluseyi: Prior to ending
cassini's mission
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by sending it
into saturn's atmosphere,
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NASA's engineers and scientists
came up with an idea --
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"let's do dives
into the region
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between the tops
of saturn's clouds
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and the innermost area
of saturn's rings.
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Narrator:
Beginning in April of 2017,
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cassini ventured between saturn
and its rings 22 times.
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Scientists called it
the grand finale.
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On these dives, cassini got
closest to saturn's cloud tops
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than any spacecraft
ever had before.
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Narrator: Saturn is an enormous
ball of hydrogen and helium,
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a gas giant.
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Fundamentally, it's a really
very different kind of planet
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than we're used to
in our everyday lives.
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Narrator:
Cassini snaps close-ups
of the planet's gaseous surface.
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The pictures reveal
a turbulent and stormy world.
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Durda:
We think of some storms on earth
as being particularly violent.
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If you've ever been
in a hurricane,
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it's not a fun place to be,
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but the storms on saturn,
the wind patterns on saturn,
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can make that look like
a mere breeze in comparison.
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Narrator: On saturn,
one storms stands out.
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It's location is marked
by a distinct shape.
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Oluseyi: One of the really weird
things is that
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whereas the bands go
around saturn,
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they're all circular
until you get to the pole,
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and then there's
a hexagonal band up there.
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No one expected that.
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Narrator:
During its lifetime,
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cassini took multiple
images of the hexagon.
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Whenever we posted
an image of the hexagon,
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the hits to the website
went through the roof.
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I think people thought
it was so mysterious.
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Bullock: When I first saw this,
I was blown away.
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I mean, who could imagine
having something this regular,
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almost geometric,
on the atmosphere of a planet?
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It's really just phenomenal.
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Narrator: In 2018, cassini data
reveals this hexagonal storm
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could be a towering structure
hundreds of miles in height.
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Plait:
It's this gigantic structure.
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It's many thousands
of miles across,
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and right in the center,
right at the pole,
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is this sort of
permanent vortex,
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a permanent hurricane.
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So, it's kind of
a creepy eye-like thing
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staring back at us.
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Narrator: Each side of the
hexagon is as wide as the earth.
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It seems artificial.
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How do you get
a hexagon-shaped storm
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or cloud structure on saturn?
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�
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narrator: Scientists think
that saturn's spin
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interacts with air currents to
create this symmetrical shape.
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But they don't know
why it's lasted for decades.
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That's the puzzle.
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How can you get
a six-sided jet stream
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that's stable for so long?
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Narrator: But while
the hexagon shape is stable,
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the color has altered.
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Over four years, it changed from
mostly blue to golden brown.
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The transformation is linked
to saturn's seasons.
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�
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plait:
The seasons on saturn are caused
by the same thing on earth.
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It's the tilt of the planet,
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and so as saturn
is going around the sun
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and it's north pole
is tipping toward the sun,
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you start to get
more light up there.
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Narrator: This sunlight
interacts with the atmosphere,
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producing suspended particles
called aerosols.
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Thaller: It actually looks
a lot like smog.
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It turns things more orange,
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so over time the hexagon
went from blue to orange.
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Narrator:
The color change happened
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during one of saturn's
northern hemisphere summers,
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but mysteriously,
the very center of the hexagon
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remained blue.
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Now, this could have been
for two reasons.
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Maybe the haze never formed
in the eye
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because the eye was shielded
from the sun,
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and the sun is responsible
for creating the brownish haze
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that we see on saturn.
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Another reason is maybe
the actual vortex
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is sucking the haze down.
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Maybe there's something like
the eye of a hurricane.
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There's haze that forms over it,
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but it gets sucked down
into the eye.
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�
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narrator:
But the storms on saturn
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aren't the only extraordinary
thing about the weather.
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When cassini dives through
the rings, it discovers rain,
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rain falling onto
the planet from space.
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�
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narrator: April 2017, cassini
embarked on its grand finale,
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following a daring new path.
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Spilker: We decided to dive in
between the rings of the planet,
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to go to a place no spacecraft
had ever flown before
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and make a unique
set of measurements.
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Narrator:
It was uncharted territory.
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Oluseyi:
They didn't know exactly
what they were going to find.
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There could be stuff there
that could have destroyed
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the cassini spacecraft.
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Narrator:
Instead, cassini encountered
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something totally
unexpected -- rain.
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�
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plait:
On earth it rains quite a bit.
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We're getting that rain
from rain clouds
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which are basically
just a few miles up.
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On saturn it also rains,
but it turns out it's raining
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onto the top
of the upper atmosphere,
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and that rain
is coming from space.
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Narrator: In 2018, cassini data
revealed the colossal weight
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of the downpour.
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Icy-grained rain hits saturn
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at a rate of several tons
per second.
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Durda: It's completely unlike
anything we've ever seen.
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Suddenly we've discovered
rain at saturn,
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but there aren't
any rain clouds.
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Where was it coming from?
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�
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narrator:
The answer is saturn's rings.
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�
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thaller:
The first thing you think of
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when you hear the word
saturn is the rings.
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They're the most dramatic
and unique aspect
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of that planet.
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�
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from afar, saturn's rings look
like this one whole structure,
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but when you look up close it's
actually a bunch of ice crystals
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and ice rocks
that make saturn's rings.
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Narrator: The size of the ring
material ranges from dust grains
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to boulders to houses.
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00:12:09,997 --> 00:12:16,534
�
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saturn's rings are well
above the atmosphere of saturn.
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They're way out in space.
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And under normal circumstances
those particles of ice
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00:12:25,212 --> 00:12:28,613
making up the rings would
just orbit saturn forever,
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00:12:28,615 --> 00:12:30,882
but things are
a little bit weird.
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�
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00:12:34,021 --> 00:12:38,089
narrator: Something is making
these orbiting ice particles
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00:12:38,091 --> 00:12:41,760
fall inward
as a kind of cosmic hail.
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�
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Walsh: Material is dripping
inwards from the rings
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00:12:47,368 --> 00:12:50,635
and falling into
the clouds of saturn.
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00:12:50,637 --> 00:12:52,838
It's like a rain
with no rain cloud.
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00:12:52,840 --> 00:12:56,374
A cosmic rain trickling in
and falling down.
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00:12:56,376 --> 00:12:58,443
�
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00:12:58,445 --> 00:13:00,712
narrator:
Cassini discovers the rain
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00:13:00,714 --> 00:13:04,116
is a mix of different kinds
of ice particles,
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00:13:04,118 --> 00:13:08,987
but doesn't reveal why
they actually rain down.
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00:13:08,989 --> 00:13:13,125
Then the researchers realized
the ice grains
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were statically charged.
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00:13:15,662 --> 00:13:17,595
Ultraviolet light from the sun,
for example,
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can blow off an electron,
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00:13:19,266 --> 00:13:21,933
and that gives these
particles a charge,
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00:13:21,935 --> 00:13:23,802
just like rubbing
a balloon on your hair
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00:13:23,804 --> 00:13:26,438
makes it stick to a wall
because of the static charge.
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00:13:29,076 --> 00:13:32,210
Well, if you have particles
that are like that,
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00:13:32,212 --> 00:13:34,545
they can be affected
by magnetism,
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00:13:34,547 --> 00:13:38,350
and saturn has
a very strong magnetic field.
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00:13:38,352 --> 00:13:40,886
Narrator:
Earth's magnetic field Springs
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00:13:40,888 --> 00:13:44,756
from it's spinning,
molten-iron core.
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00:13:44,758 --> 00:13:48,360
Although saturn probably has
a rocky center,
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00:13:48,362 --> 00:13:52,698
it's mostly a giant ball
of hydrogen and helium,
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00:13:52,700 --> 00:13:55,767
but deep in its interior,
scientists think something
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00:13:55,769 --> 00:13:59,905
much more exotic is going on.
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00:13:59,907 --> 00:14:01,639
We don't have enough data
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00:14:01,641 --> 00:14:04,509
to know exactly what's going on
in saturn's interior,
249
00:14:04,511 --> 00:14:06,378
but we do know
the broad strokes.
250
00:14:06,380 --> 00:14:08,914
Narrator:
Within saturn's interior,
251
00:14:08,916 --> 00:14:12,451
extreme pressures
and temperatures force hydrogen
252
00:14:12,453 --> 00:14:14,920
to stop acting like a gas,
253
00:14:14,922 --> 00:14:19,457
turning it into spinning
liquid-metallic hydrogen.
254
00:14:19,459 --> 00:14:21,326
Durda: You've got this band
of electrons
255
00:14:21,328 --> 00:14:23,528
that can just wander
freely through that fluid,
256
00:14:23,530 --> 00:14:27,465
so in that way, liquid hydrogen
under extreme pressure
257
00:14:27,467 --> 00:14:30,202
can act like a metal.
258
00:14:30,204 --> 00:14:33,071
Narrator:
The magnetic field generated
259
00:14:33,073 --> 00:14:36,274
by the spinning
metallic-hydrogen outer core
260
00:14:36,276 --> 00:14:39,878
pulls the ice particles
from the rings.
261
00:14:39,880 --> 00:14:41,679
Plait:
These charged ice particles
262
00:14:41,681 --> 00:14:44,282
are then drawn in
by saturn's field.
263
00:14:44,284 --> 00:14:46,084
They follow
the magnetic field lines
264
00:14:46,086 --> 00:14:51,756
and rain down onto
the atmosphere of saturn.
265
00:14:51,758 --> 00:14:55,227
Narrator: Cassini had revealed
several tons of material
266
00:14:55,229 --> 00:14:57,896
is raining down
on saturn every second,
267
00:14:57,898 --> 00:15:01,099
but how much stuff
is actually in the rings?
268
00:15:01,101 --> 00:15:05,503
Again, cassini provides
the answer.
269
00:15:05,505 --> 00:15:07,105
Thaller:
In the final days of cassini,
270
00:15:07,107 --> 00:15:10,442
we actually flew in between
the planet saturn and the rings,
271
00:15:10,444 --> 00:15:13,111
and the gravity data
was able to separate out
272
00:15:13,113 --> 00:15:15,113
how much mass is coming
from the planet
273
00:15:15,115 --> 00:15:17,248
and how much is coming
from the rings,
274
00:15:17,250 --> 00:15:18,516
and the surprise was the rings
275
00:15:18,518 --> 00:15:20,519
are actually not
very massive at all.
276
00:15:20,521 --> 00:15:22,920
�
277
00:15:22,922 --> 00:15:25,056
narrator:
Even though they cover an area
278
00:15:25,058 --> 00:15:27,792
as big as the moon's orbit
around earth,
279
00:15:27,794 --> 00:15:31,462
saturn's rings are 100,000 times
less massive
280
00:15:31,464 --> 00:15:34,131
than our own small planet.
281
00:15:34,133 --> 00:15:36,601
�
282
00:15:36,603 --> 00:15:38,669
plait:
They're lighter than we thought.
283
00:15:38,671 --> 00:15:41,673
There's not as much
material there.
284
00:15:41,675 --> 00:15:47,745
Narrator:
The mass of the rings is
a valuable clue about their age.
285
00:15:47,747 --> 00:15:50,081
A more massive ring
can hold itself together
286
00:15:50,083 --> 00:15:53,018
for much longer
than a less massive ring,
287
00:15:53,020 --> 00:15:56,488
so if there's not a lot of stuff
there, it must be younger.
288
00:15:56,490 --> 00:15:59,291
�
289
00:15:59,293 --> 00:16:03,228
narrator: So, how long have
saturn's rings been in place,
290
00:16:03,230 --> 00:16:06,364
and what is keeping them there?
291
00:16:06,366 --> 00:16:08,967
It's something that I don't
even think I could have imagined
292
00:16:08,969 --> 00:16:10,635
if I tried.
293
00:16:20,514 --> 00:16:30,121
�
294
00:16:30,123 --> 00:16:32,457
narrator:
As cassini orbited saturn,
295
00:16:32,459 --> 00:16:36,528
it revealed incredible insights
into the planet's rings.
296
00:16:36,530 --> 00:16:43,802
�
297
00:16:43,804 --> 00:16:46,538
the photos that came
from cassini of the rings
298
00:16:46,540 --> 00:16:50,275
are unlike anything
that I could ever imagine.
299
00:16:50,277 --> 00:16:53,544
Oluseyi: If I was alien
visiting our solar system,
300
00:16:53,546 --> 00:16:55,680
I don't know what would
stand out to me more,
301
00:16:55,682 --> 00:17:00,552
the blue marble or saturn
and its amazing rings.
302
00:17:00,554 --> 00:17:03,021
Thaller: One of the biggest
questions about the rings
303
00:17:03,023 --> 00:17:05,022
is how old are they.
304
00:17:05,024 --> 00:17:06,825
Could something like that
really have existed
305
00:17:06,827 --> 00:17:08,426
from the beginning
of the solar system,
306
00:17:08,428 --> 00:17:12,496
or is it relatively recent?
307
00:17:12,498 --> 00:17:16,635
Narrator:
Cassini provided an answer.
308
00:17:16,637 --> 00:17:19,904
The rings could be as young
as only 100 million years old.
309
00:17:19,906 --> 00:17:22,507
A couple of clues --
the low mass and the fact
310
00:17:22,509 --> 00:17:23,842
that they're so bright and icy
311
00:17:23,844 --> 00:17:25,977
that it hasn't had time
to get polluted
312
00:17:25,979 --> 00:17:29,046
from all the micrometeoroids
and darkened
313
00:17:29,048 --> 00:17:33,050
over a long time like the age
of the solar system.
314
00:17:33,052 --> 00:17:34,919
Thaller:
So, the amazing thing is
315
00:17:34,921 --> 00:17:36,121
that, you know,
if you were on earth
316
00:17:36,123 --> 00:17:37,722
about the time of the dinosaurs,
317
00:17:37,724 --> 00:17:40,791
there might have been a saturn
in the sky with no rings.
318
00:17:40,793 --> 00:17:44,729
�
319
00:17:44,731 --> 00:17:47,532
narrator:
So, if the rings didn't form
320
00:17:47,534 --> 00:17:51,403
at the same time as saturn,
how did they form,
321
00:17:51,405 --> 00:17:53,404
and what's keeping them
in place?
322
00:17:53,406 --> 00:18:00,612
�
323
00:18:00,614 --> 00:18:03,148
to form the rings
100 million years ago,
324
00:18:03,150 --> 00:18:04,548
you need to find an object --
325
00:18:04,550 --> 00:18:07,285
maybe a comet or a moon
gets too close to saturn.
326
00:18:07,287 --> 00:18:10,955
Saturn's gravity tears it apart
and forms the rings.
327
00:18:10,957 --> 00:18:13,758
�
328
00:18:13,760 --> 00:18:16,161
narrator:
As the object is torn apart,
329
00:18:16,163 --> 00:18:21,632
the pieces spread out around
saturn to form the rings.
330
00:18:21,634 --> 00:18:27,572
They keep colliding, breaking
into smaller and smaller pieces.
331
00:18:27,574 --> 00:18:30,375
Like pebbles on a beach,
subsequent jostling
332
00:18:30,377 --> 00:18:32,177
and self collisions
between each other
333
00:18:32,179 --> 00:18:33,912
will take
the sharp edges off of them
334
00:18:33,914 --> 00:18:35,647
creating rounded particles.
335
00:18:35,649 --> 00:18:38,717
�
336
00:18:38,719 --> 00:18:41,652
narrator: From a distance,
saturn's rings appear
337
00:18:41,654 --> 00:18:45,590
incredibly thin
and almost perfectly flat,
338
00:18:45,592 --> 00:18:49,460
but appearances
can be deceptive.
339
00:18:49,462 --> 00:18:51,662
Lanza: One of our results
from cassini
340
00:18:51,664 --> 00:18:54,065
as it took its final plunge
into saturn
341
00:18:54,067 --> 00:18:56,134
was as we flew past those rings,
342
00:18:56,136 --> 00:19:01,206
we noticed that the rings were
actually not a uniform density.
343
00:19:01,208 --> 00:19:03,008
That's something
that nobody had seen.
344
00:19:03,010 --> 00:19:04,809
I mean, you had to get
really close to see that,
345
00:19:04,811 --> 00:19:07,144
and it wasn't expected.
346
00:19:07,146 --> 00:19:09,080
Spilker:
I'm a ring scientist,
347
00:19:09,082 --> 00:19:11,416
and I just love seeing
that detail
348
00:19:11,418 --> 00:19:12,883
and trying to figure out
349
00:19:12,885 --> 00:19:17,255
why do saturn's rings
look the way they do.
350
00:19:17,257 --> 00:19:20,091
Durda: There are
very intricate structures,
351
00:19:20,093 --> 00:19:21,960
knife-edge little ringlets
352
00:19:21,962 --> 00:19:25,163
and, like, almost like
the grooves in a record.
353
00:19:25,165 --> 00:19:26,965
It begs the question, of course,
354
00:19:26,967 --> 00:19:30,702
where do those structures
come from.
355
00:19:30,704 --> 00:19:34,439
�
356
00:19:34,441 --> 00:19:38,376
narrator: The clue is hidden
within the rings.
357
00:19:38,378 --> 00:19:41,646
There's not five rings.
There's not 500 rings.
358
00:19:41,648 --> 00:19:43,381
There's thousands of rings.
359
00:19:43,383 --> 00:19:47,652
There's potentially millions
of tiny, little ringlets
360
00:19:47,654 --> 00:19:51,589
with small gaps between them,
and sometimes large gaps,
361
00:19:51,591 --> 00:19:57,462
and cassini saw that there are
moons embedded inside the rings.
362
00:19:57,464 --> 00:20:01,799
�
363
00:20:01,801 --> 00:20:06,004
narrator:
These moons and moonlets
seem to be shaping the rings.
364
00:20:06,006 --> 00:20:09,541
�
365
00:20:09,543 --> 00:20:11,008
thaller: When I think about
the rings of saturn,
366
00:20:11,010 --> 00:20:13,344
I almost hear symphonies
playing in my head.
367
00:20:13,346 --> 00:20:16,614
It's all about this wonderful
structure and these harmonies,
368
00:20:16,616 --> 00:20:18,682
the balances between gravity.
369
00:20:18,684 --> 00:20:21,018
So, we use the word "resonance."
370
00:20:21,020 --> 00:20:23,488
�
371
00:20:23,490 --> 00:20:26,291
narrator: Saturn's moons
stir the rings particles
372
00:20:26,293 --> 00:20:30,028
with their gravitational pull,
creating waves.
373
00:20:30,030 --> 00:20:33,297
�
374
00:20:33,299 --> 00:20:37,702
spilker: There's a special place
where the resonance exists.
375
00:20:37,704 --> 00:20:39,971
Imagine where the ring particles
are going around twice
376
00:20:39,973 --> 00:20:42,774
for each single time
the moon goes around.
377
00:20:42,776 --> 00:20:44,442
It's like pushing someone
on a swing.
378
00:20:44,444 --> 00:20:46,311
If you push them
at just the right rate
379
00:20:46,313 --> 00:20:48,112
they go higher and higher,
380
00:20:48,114 --> 00:20:52,116
and these places are
where the waves generated.
381
00:20:52,118 --> 00:20:53,918
Thaller: So, there's
this ballet, this dance,
382
00:20:53,920 --> 00:20:55,586
between the ring and the moons.
383
00:20:55,588 --> 00:20:58,656
It is one of the most elegant
things I've ever seen.
384
00:20:58,658 --> 00:21:06,331
�
385
00:21:06,333 --> 00:21:09,067
narrator: But the rings aren't
just being shaped
386
00:21:09,069 --> 00:21:11,402
into waves by the moons.
387
00:21:11,404 --> 00:21:14,605
They're being held
in place by them.
388
00:21:14,607 --> 00:21:16,674
Sutter: Through
gravitational interactions,
389
00:21:16,676 --> 00:21:21,146
these moons might be shaping
the rings, shepherding them,
390
00:21:21,148 --> 00:21:26,017
keeping their flock in a nice,
tight orbit around the planet.
391
00:21:26,019 --> 00:21:28,652
�
392
00:21:28,654 --> 00:21:32,290
narrator:
In 2017, cassini reveals
393
00:21:32,292 --> 00:21:34,425
there are more
than one or two moons
394
00:21:34,427 --> 00:21:36,794
shepherding the rings.
395
00:21:36,796 --> 00:21:41,565
A whole team of moons holds
saturn's outermost visible ring,
396
00:21:41,567 --> 00:21:45,169
the "a" ring, in place.
397
00:21:45,171 --> 00:21:47,304
One of the really cool things
that cassini discovered
398
00:21:47,306 --> 00:21:48,706
during its death dive
399
00:21:48,708 --> 00:21:50,708
was that there are
seven moons of saturn
400
00:21:50,710 --> 00:21:51,976
that are all working together
401
00:21:51,978 --> 00:21:54,512
to keep that ring system
in configuration,
402
00:21:54,514 --> 00:21:56,714
so it's like
the magnificent seven
403
00:21:56,716 --> 00:21:58,249
holding this thing together.
404
00:21:58,251 --> 00:22:02,587
�
405
00:22:02,589 --> 00:22:07,325
narrator:
Of the seven magnificent moons,
the biggest is mimas.
406
00:22:07,327 --> 00:22:09,594
It's one-eighth
the size of our moon.
407
00:22:09,596 --> 00:22:12,396
�
408
00:22:12,398 --> 00:22:16,134
the smallest, pan,
is only 20 miles across.
409
00:22:16,136 --> 00:22:18,269
�
410
00:22:18,271 --> 00:22:20,004
acting in combination,
411
00:22:20,006 --> 00:22:25,276
these moons hold
all of saturn's rings in check.
412
00:22:25,278 --> 00:22:28,145
Howett: So, it's these
seven moons working together
413
00:22:28,147 --> 00:22:30,615
forming the ring system
that we see today.
414
00:22:30,617 --> 00:22:38,823
�
415
00:22:38,825 --> 00:22:42,560
narrator: Cassini has truly
opened our eyes to the wonder
416
00:22:42,562 --> 00:22:46,497
of saturn's rings
and many moons.
417
00:22:46,499 --> 00:22:50,101
Saturn has a lot of moons --
I mean, a lot of moons,
418
00:22:50,103 --> 00:22:53,037
and they're all really
interesting and different.
419
00:22:53,039 --> 00:22:54,906
Coming up with the exact number
is a little difficult
420
00:22:54,908 --> 00:22:59,109
'cause it almost changes every
year as we discover new ones.
421
00:22:59,111 --> 00:23:02,747
Narrator: The latest count
is over 60 moons,
422
00:23:02,749 --> 00:23:05,183
each with a different character,
423
00:23:05,185 --> 00:23:11,256
but one has a split personality
and a very dark side.
424
00:23:21,268 --> 00:23:29,674
�
425
00:23:29,676 --> 00:23:32,410
narrator: May 2017.
426
00:23:32,412 --> 00:23:35,280
Cassini was
on its grand finale.
427
00:23:35,282 --> 00:23:38,515
�
428
00:23:38,517 --> 00:23:42,754
the probe snapped its last photo
of a strange moon
429
00:23:42,756 --> 00:23:47,892
2 million miles
from saturn...
430
00:23:47,894 --> 00:23:50,028
Iapetus.
431
00:23:50,030 --> 00:23:52,363
Porco: Iapetus was discovered
hundreds of years ago,
432
00:23:52,365 --> 00:23:55,299
and right from the start
it was recognized
433
00:23:55,301 --> 00:23:57,368
that one side of it
was very bright,
434
00:23:57,370 --> 00:24:02,707
and the other side
was as dark as dark can be.
435
00:24:02,709 --> 00:24:04,709
Narrator:
This dark and light moon
436
00:24:04,711 --> 00:24:08,312
confused Italian astronomer
Giovanni cassini
437
00:24:08,314 --> 00:24:13,451
when he first spotted
it in 1671.
438
00:24:13,453 --> 00:24:17,054
It's been puzzling scientists
ever since.
439
00:24:17,056 --> 00:24:19,189
�
440
00:24:19,191 --> 00:24:22,326
so, we get there with cassini,
and of course iapetus
441
00:24:22,328 --> 00:24:25,196
was a very major target for us
442
00:24:25,198 --> 00:24:26,864
because we were interested
to know
443
00:24:26,866 --> 00:24:32,136
what was with this crazy
two-toned moon.
444
00:24:32,138 --> 00:24:34,671
�
445
00:24:34,673 --> 00:24:38,609
narrator: Cassini reveals that
the answer lies even farther out
446
00:24:38,611 --> 00:24:43,814
from saturn
in the form of another moon.
447
00:24:43,816 --> 00:24:46,484
There's one pretty big
but really dark moon,
448
00:24:46,486 --> 00:24:49,153
Phoebe, that's
outside of iapetus
449
00:24:49,155 --> 00:24:52,690
and is orbiting the opposite
direction around saturn.
450
00:24:52,692 --> 00:24:58,562
Narrator:
Pheobe orbits saturn four times
farther out than iapetus.
451
00:24:58,564 --> 00:25:02,500
As it travels around the planet,
micrometeorite impacts
452
00:25:02,502 --> 00:25:07,571
the moon's surface generate
a cloud of dark dust.
453
00:25:07,573 --> 00:25:12,243
The dust from Phoebe
actually creates a large ring.
454
00:25:12,245 --> 00:25:15,446
Walsh: A ring of dark, dusty
material that's drifting inwards
455
00:25:15,448 --> 00:25:18,849
toward saturn going the
opposite direction of iapetus,
456
00:25:18,851 --> 00:25:20,717
which is the perfect
material for iapetus
457
00:25:20,719 --> 00:25:23,787
to sweep up in its orbit
to create one dark side.
458
00:25:23,789 --> 00:25:29,460
�
459
00:25:29,462 --> 00:25:32,062
narrator:
Iapetus has one dark side
460
00:25:32,064 --> 00:25:34,599
because it's tidally
locked to saturn.
461
00:25:37,137 --> 00:25:42,006
One side always faces
the planet
462
00:25:42,008 --> 00:25:47,344
while another side drives
forward through the dust.
463
00:25:47,346 --> 00:25:49,747
Walsh: It's plowing through
a bunch of dust
464
00:25:49,749 --> 00:25:51,349
that's sticking to
the front side,
465
00:25:51,351 --> 00:25:54,018
kind of like bugs
on a windshield.
466
00:25:54,020 --> 00:25:56,621
Narrator: Cassini discovered
this dark dust
467
00:25:56,623 --> 00:25:59,023
makes the leading side warmer
468
00:25:59,025 --> 00:26:03,428
than the trailing bright side
by 50 degrees fahrenheit.
469
00:26:03,430 --> 00:26:05,429
Plait: When you have something
that's dark like the dust
470
00:26:05,431 --> 00:26:08,166
on the leading edge of iapetus,
that gets warmer.
471
00:26:08,168 --> 00:26:09,633
It absorbs sunlight better,
472
00:26:09,635 --> 00:26:13,570
and if it's warmer then things
that can evaporate more easily,
473
00:26:13,572 --> 00:26:19,843
like water for example,
tends to blow off the surface.
474
00:26:19,845 --> 00:26:23,046
Narrator: The front side
gets darker and warmer.
475
00:26:23,048 --> 00:26:25,650
�
476
00:26:25,652 --> 00:26:27,919
any visible ice turns to vapor
477
00:26:27,921 --> 00:26:30,454
and makes its way
to the colder trailing side
478
00:26:30,456 --> 00:26:32,456
where it refreezes.
479
00:26:32,458 --> 00:26:34,392
�
480
00:26:34,394 --> 00:26:39,730
so, the white side gets whiter
and the dark side gets darker.
481
00:26:39,732 --> 00:26:42,066
Plait: So, you have
this self-sustaining dark side
482
00:26:42,068 --> 00:26:44,869
and bright side, and you wind up
with this two-faced moon.
483
00:26:44,871 --> 00:26:49,072
�
484
00:26:49,074 --> 00:26:54,144
narrator:
Iapetus' two sides are strange,
485
00:26:54,146 --> 00:26:56,814
but cassini discovers
that they're not
486
00:26:56,816 --> 00:27:01,084
the weirdest thing
about this moon.
487
00:27:01,086 --> 00:27:04,188
The weirdest thing
is that it is a walnut.
488
00:27:04,190 --> 00:27:09,494
�
489
00:27:09,496 --> 00:27:13,030
iapetus has a mountain range
that exactly circles its equator
490
00:27:13,032 --> 00:27:14,699
all the way around the moon,
491
00:27:14,701 --> 00:27:17,435
a mountain range higher
than the himalayas.
492
00:27:17,437 --> 00:27:25,909
�
493
00:27:25,911 --> 00:27:30,314
narrator: These mountains are
over 12 miles high,
494
00:27:30,316 --> 00:27:33,384
more than twice the altitude
of earth's highest peak,
495
00:27:33,386 --> 00:27:37,488
mount Everest.
496
00:27:37,490 --> 00:27:40,157
It's crazy.
It's this huge crazy Ridge
497
00:27:40,159 --> 00:27:42,192
on this really strange moon.
498
00:27:42,194 --> 00:27:45,128
�
499
00:27:45,130 --> 00:27:48,933
how do you form a smooth
Equatorial mountain Ridge
500
00:27:48,935 --> 00:27:50,734
around an entire world?
501
00:27:50,736 --> 00:27:54,672
Plait: A really interesting idea
is that for some period of time,
502
00:27:54,674 --> 00:27:57,675
just like saturn itself
has this gigantic ring system,
503
00:27:57,677 --> 00:28:00,344
iapetus had
a ring system, as well.
504
00:28:00,346 --> 00:28:02,480
�
505
00:28:02,482 --> 00:28:06,883
narrator: Over time,
iapetus' ring collapsed,
506
00:28:06,885 --> 00:28:09,453
falling in a circle
around the moon.
507
00:28:11,424 --> 00:28:13,090
Walsh:
As it fell to the surface,
508
00:28:13,092 --> 00:28:14,491
it built up a mountain range
509
00:28:14,493 --> 00:28:16,627
right below
where the ring was orbiting
510
00:28:16,629 --> 00:28:18,162
so that all that material
just built up
511
00:28:18,164 --> 00:28:19,697
and built a mountain range
512
00:28:19,699 --> 00:28:21,699
ringing the equator
all the way around.
513
00:28:21,701 --> 00:28:25,702
�
514
00:28:25,704 --> 00:28:27,572
narrator:
Walnut-shaped iapetus
515
00:28:27,574 --> 00:28:31,441
is not the only
strange moon around saturn.
516
00:28:31,443 --> 00:28:33,244
Cassini discovered a moon
517
00:28:33,246 --> 00:28:37,648
hiding many secrets
beneath its icy surface --
518
00:28:37,650 --> 00:28:42,253
enceladus, a moon
that could even harbor life.
519
00:28:50,796 --> 00:28:55,866
�
520
00:28:55,868 --> 00:29:01,138
�
521
00:29:01,140 --> 00:29:03,874
narrator: August 2017,
522
00:29:03,876 --> 00:29:07,878
cassini captured six images
of enceladus,
523
00:29:07,880 --> 00:29:09,880
�
524
00:29:09,882 --> 00:29:14,618
one of the most intriguing moons
in the solar system.
525
00:29:14,620 --> 00:29:18,955
Enceladus is a relatively
small moon of saturn
526
00:29:18,957 --> 00:29:20,491
that's pretty easy to ignore,
527
00:29:20,493 --> 00:29:25,162
but once you pay attention
to it, hosts a lot of surprises.
528
00:29:25,164 --> 00:29:29,700
�
529
00:29:29,702 --> 00:29:34,372
narrator: We've known something
was unusual about this icy world
530
00:29:34,374 --> 00:29:39,977
ever since the voyager mission
took photographs in 1980.
531
00:29:39,979 --> 00:29:42,780
Spilker: We thought that
enceladus would be frozen solid,
532
00:29:42,782 --> 00:29:46,116
and yet we knew from voyager
data the surface
533
00:29:46,118 --> 00:29:48,919
of enceladus was bright white.
534
00:29:48,921 --> 00:29:51,022
Porco:
And we could see on the surface
535
00:29:51,024 --> 00:29:54,392
that vast tracks of it
were smooth,
536
00:29:54,394 --> 00:29:57,527
at least at the resolution
that we had with voyager,
537
00:29:57,529 --> 00:30:01,865
and that immediately says that
there's been internal activity
538
00:30:01,867 --> 00:30:04,201
because that's really,
on an airless moon,
539
00:30:04,203 --> 00:30:08,472
that's the only process
that could erase craters.
540
00:30:08,474 --> 00:30:10,808
Narrator:
Scientists suspected something
541
00:30:10,810 --> 00:30:15,679
was actively
resurfacing enceladus,
542
00:30:15,681 --> 00:30:20,751
filling in its craters
to make it smooth and bright.
543
00:30:20,753 --> 00:30:25,823
Then cassini sent back pictures
of enceladus backlit,
544
00:30:25,825 --> 00:30:28,225
and all was revealed.
545
00:30:28,227 --> 00:30:31,561
Spilker: We saw these icy jets
shooting out from enceladus,
546
00:30:31,563 --> 00:30:35,700
and everyone was so amazed
that a moon so tiny
547
00:30:35,702 --> 00:30:41,172
and assumed to be a frozen-solid
ice cube could be so active.
548
00:30:41,174 --> 00:30:46,109
�
549
00:30:46,111 --> 00:30:52,583
narrator:
Jets of almost luminous material
sprang out of geysers.
550
00:30:52,585 --> 00:30:56,120
When I first saw a picture
of a geyser on enceladus,
551
00:30:56,122 --> 00:30:58,188
I mean, I was floored.
That's amazing.
552
00:30:58,190 --> 00:31:01,458
I had no idea
that was even possible.
553
00:31:01,460 --> 00:31:06,830
The cassini discovery of geysers
on enceladus was a game changer.
554
00:31:06,832 --> 00:31:09,933
All of the sudden,
here's water jetting out.
555
00:31:09,935 --> 00:31:12,736
It was, like,
too good to be true.
556
00:31:12,738 --> 00:31:18,408
Narrator:
Cassini revealed the geysers
are blasting out liquid water.
557
00:31:18,410 --> 00:31:22,880
Enceladus is not
a solid ball of ice.
558
00:31:22,882 --> 00:31:24,815
Spilker: As we got more data
from cassini,
559
00:31:24,817 --> 00:31:27,485
we found that enceladus
had a wobble
560
00:31:27,487 --> 00:31:29,086
that was too large
for a body
561
00:31:29,088 --> 00:31:31,889
that was frozen solid
all the way through,
562
00:31:31,891 --> 00:31:34,558
and that told us
that a liquid water ocean
563
00:31:34,560 --> 00:31:36,960
circled a rocky core.
564
00:31:36,962 --> 00:31:39,830
Plait: Enceladus has
liquid water under its surface,
565
00:31:39,832 --> 00:31:42,233
and it may very well
be an ocean
566
00:31:42,235 --> 00:31:45,169
basically covering
the inside of that moon,
567
00:31:45,171 --> 00:31:48,706
but where's the heat
coming from?
568
00:31:48,708 --> 00:31:51,108
Narrator:
When planets and moons form,
569
00:31:51,110 --> 00:31:54,778
their cores are incredibly hot,
570
00:31:54,780 --> 00:31:57,914
but over time they cool down.
571
00:31:57,916 --> 00:32:02,185
The smaller the planet,
the faster it cools.
572
00:32:02,187 --> 00:32:06,924
A tiny world like enceladus over
a billion miles from the sun
573
00:32:06,926 --> 00:32:10,594
should have frozen solid by now.
574
00:32:10,596 --> 00:32:12,463
Oluseyi:
That's what we expected.
575
00:32:12,465 --> 00:32:14,932
If things are smaller,
then they would be roughly dead,
576
00:32:14,934 --> 00:32:16,534
and they'd be
covered by craters,
577
00:32:16,536 --> 00:32:21,005
but enceladus shows us
that that's not the case at all.
578
00:32:21,007 --> 00:32:24,408
Narrator: How could a tiny moon
so far from the sun
579
00:32:24,410 --> 00:32:26,944
have enough warmth
for liquid water?
580
00:32:26,946 --> 00:32:31,348
One idea is tidal heating.
581
00:32:31,350 --> 00:32:32,683
Howett: If you've ever played
racquetball,
582
00:32:32,685 --> 00:32:34,351
you know as you play the game
the ball heats up,
583
00:32:34,353 --> 00:32:37,621
and this is because as the ball
hits the racket or the wall,
584
00:32:37,623 --> 00:32:40,290
it's getting squished,
and then it relaxes.
585
00:32:40,292 --> 00:32:43,494
�
586
00:32:43,496 --> 00:32:46,430
saturn's gravity squishes
and relaxes
587
00:32:46,432 --> 00:32:48,966
enceladus as it orbits
the planet,
588
00:32:48,968 --> 00:32:53,103
heating it like a racquetball,
589
00:32:53,105 --> 00:32:55,972
but this alone
wouldn't generate enough heat
590
00:32:55,974 --> 00:32:59,443
to stop enceladus' water
from freezing.
591
00:32:59,445 --> 00:33:04,448
Something else must be
going on in the core.
592
00:33:04,450 --> 00:33:09,520
Plait:
What if the core of enceladus
is actually kind of gravelly?
593
00:33:09,522 --> 00:33:12,189
Instead of it just being solid,
it's actually made of rocks
594
00:33:12,191 --> 00:33:14,258
and pebbles
and gravel all put together.
595
00:33:14,260 --> 00:33:16,860
Then what happens is
as the tides are stretching
596
00:33:16,862 --> 00:33:20,264
and squeezing it, those rocks
are rubbing together,
597
00:33:20,266 --> 00:33:23,333
and that actually generates
even more energy.
598
00:33:23,335 --> 00:33:26,136
�
599
00:33:26,138 --> 00:33:30,941
narrator: 2017, a computer model
based on cassini data
600
00:33:30,943 --> 00:33:34,811
revealed this tidal friction
generates more energy
601
00:33:34,813 --> 00:33:38,949
than America's biggest
power station.
602
00:33:38,951 --> 00:33:44,488
Water heated to 194 degrees
fahrenheit rises to the surface.
603
00:33:44,490 --> 00:33:46,823
It sprays through cracks
in the moon's
604
00:33:46,825 --> 00:33:50,093
south pole
creating misty plumes.
605
00:33:50,095 --> 00:33:53,564
�
606
00:33:53,566 --> 00:33:56,366
spilker: As we flew seven times
through and tasted and sampled
607
00:33:56,368 --> 00:34:00,104
the gas and the particles,
we found salty particles,
608
00:34:00,106 --> 00:34:04,374
that the ocean was salty very
much like the earth's ocean.
609
00:34:04,376 --> 00:34:09,046
We found hydocarbons, methane,
carbon dioxide, ammonia.
610
00:34:09,048 --> 00:34:12,049
We found the key ingredients
for life
611
00:34:12,051 --> 00:34:16,987
coming out of the jets
of enceladus -- so remarkable.
612
00:34:16,989 --> 00:34:19,656
�
613
00:34:19,658 --> 00:34:24,728
narrator: In 2018, scientists
reanalyze the enceladus data
614
00:34:24,730 --> 00:34:29,867
and found something
even more remarkable --
615
00:34:29,869 --> 00:34:33,803
complex organic molecules.
616
00:34:33,805 --> 00:34:37,674
Plait: What they found were
larger organic compounds
617
00:34:37,676 --> 00:34:39,142
than initially thought there.
618
00:34:39,144 --> 00:34:42,546
At first, it was just dust and
water and some basic organics.
619
00:34:42,548 --> 00:34:44,681
Now they're seeing more
complex stuff
620
00:34:44,683 --> 00:34:47,418
coming up
from enceladus' interior,
621
00:34:47,420 --> 00:34:51,722
and that asks the question
what else is down there.
622
00:34:51,724 --> 00:34:57,227
Narrator:
On earth, we find life huddled
around hot vents on the seabed.
623
00:34:57,229 --> 00:35:02,032
Could the same be true
in the oceans of enceladus?
624
00:35:02,034 --> 00:35:07,237
Could these complex organic
molecules be signs of life?
625
00:35:07,239 --> 00:35:09,572
McKay: My favorite name
for them is "goo."
626
00:35:09,574 --> 00:35:13,377
They're gooey things,
and think of life
627
00:35:13,379 --> 00:35:15,311
as a collection
of gooey-like molecules.
628
00:35:15,313 --> 00:35:18,315
Now, that doesn't mean that all
gooey molecules are biological,
629
00:35:18,317 --> 00:35:20,384
but certainly biology makes use
630
00:35:20,386 --> 00:35:23,787
of these complex
organic molecules.
631
00:35:23,789 --> 00:35:26,724
Narrator:
Deep in enceladus' oceans,
632
00:35:26,726 --> 00:35:32,262
heat from hydrothermal vents
drives chemical reactions...
633
00:35:32,264 --> 00:35:36,200
Combining simple molecules
like methane and hydrogen
634
00:35:36,202 --> 00:35:41,604
into longer, complex
organic molecules,
635
00:35:41,606 --> 00:35:47,745
complex molecules that could
serve as the precursors to life.
636
00:35:47,747 --> 00:35:50,814
What's amazing is the chemistry
of that ocean.
637
00:35:50,816 --> 00:35:53,150
Everything needed for life
is there.
638
00:35:53,152 --> 00:35:55,753
The eternal question is
is there life in the universe,
639
00:35:55,755 --> 00:35:59,156
and enceladus is a great place
to try and answer that question.
640
00:35:59,158 --> 00:36:04,027
�
641
00:36:04,029 --> 00:36:06,696
narrator:
And cassini revealed secrets
642
00:36:06,698 --> 00:36:10,700
of another moon of saturn
with amazing chemistry,
643
00:36:10,702 --> 00:36:14,104
a giant moon
with earth-like features --
644
00:36:14,106 --> 00:36:17,774
rivers, lakes, and dunes --
645
00:36:17,776 --> 00:36:19,710
titan.
646
00:36:28,453 --> 00:36:36,660
�
647
00:36:36,662 --> 00:36:40,531
narrator: September 2017,
648
00:36:40,533 --> 00:36:42,599
four days
before the mission ended,
649
00:36:42,601 --> 00:36:45,135
cassini flew past
one of saturn's
650
00:36:45,137 --> 00:36:50,140
most spectacular moons,
titan.
651
00:36:50,142 --> 00:36:53,343
Here's why I like titan --
not just because it has a name
652
00:36:53,345 --> 00:36:56,146
that means "big" and "strong,"
which makes you think of me,
653
00:36:56,148 --> 00:36:59,750
but because it has
an extensive atmosphere
654
00:36:59,752 --> 00:37:02,886
that's made primarily
of nitrogen, just like earth's.
655
00:37:02,888 --> 00:37:06,490
�
656
00:37:06,492 --> 00:37:09,359
sutter:
Titan's always been a mystery.
657
00:37:09,361 --> 00:37:13,564
What is hiding underneath
that thick atmosphere?
658
00:37:13,566 --> 00:37:16,500
�
659
00:37:16,502 --> 00:37:18,569
narrator:
Viewed through a telescope,
660
00:37:18,571 --> 00:37:22,639
this moon seemed little more
than a hazy orange ball.
661
00:37:22,641 --> 00:37:26,443
Then cassini launched
the huygens probe.
662
00:37:26,445 --> 00:37:28,712
It traveled beneath the clouds
663
00:37:28,714 --> 00:37:33,517
and sent back images
of titan's surface.
664
00:37:33,519 --> 00:37:39,923
I almost can't describe
how thrilling it was,
665
00:37:39,925 --> 00:37:42,793
the landing of the huygens probe
on the surface of titan.
666
00:37:42,795 --> 00:37:45,462
It was like a Jules verne
adventure come true.
667
00:37:45,464 --> 00:37:53,136
�
668
00:37:53,138 --> 00:37:55,138
lanza:
The images that you see
669
00:37:55,140 --> 00:37:56,673
as you're coming
through the atmosphere
670
00:37:56,675 --> 00:37:58,208
and the world emerges,
671
00:37:58,210 --> 00:38:02,212
and it's this incredible world
that looks so familiar.
672
00:38:02,214 --> 00:38:05,749
Mountains and these streams
flowing into this ocean.
673
00:38:05,751 --> 00:38:07,284
Wow!
674
00:38:07,286 --> 00:38:10,553
Sutter: You might be standing
on the shores of a lake,
675
00:38:10,555 --> 00:38:13,023
but this lake
doesn't look like water.
676
00:38:13,025 --> 00:38:14,357
Instead, it's methane.
677
00:38:14,359 --> 00:38:16,493
It's much darker.
678
00:38:16,495 --> 00:38:18,629
Durda:
It's a frigid, bizarre world
679
00:38:18,631 --> 00:38:21,164
with geologic features
that look familiar,
680
00:38:21,166 --> 00:38:23,766
but in a very,
very alien setting.
681
00:38:23,768 --> 00:38:27,237
Narrator: Titan is like a home
away from home.
682
00:38:27,239 --> 00:38:32,309
It's just colder by about
350 degrees fahrenheit.
683
00:38:32,311 --> 00:38:35,312
Radebaugh: The cassini mission
revealed that titan is
684
00:38:35,314 --> 00:38:38,248
really exactly like earth
in terms of its landscape.
685
00:38:38,250 --> 00:38:40,183
In fact, almost a quarter
of the body
686
00:38:40,185 --> 00:38:43,787
is covered in sand dunes exactly
like what you see behind me.
687
00:38:43,789 --> 00:38:48,692
�
688
00:38:48,694 --> 00:38:54,998
narrator:
But cassini reveals titan's
dunes are not what they seem.
689
00:38:55,000 --> 00:38:57,533
Radebaugh: The dunes on titan
are made of something
690
00:38:57,535 --> 00:38:59,936
completely different
than sand dunes on the earth.
691
00:38:59,938 --> 00:39:02,405
You know, most sand on the earth
is made of quartz,
692
00:39:02,407 --> 00:39:04,607
but on titan sand dunes,
it turns out,
693
00:39:04,609 --> 00:39:06,610
are made entirely of organics.
694
00:39:08,814 --> 00:39:11,814
Narrator: Titan's sand is made
from tiny particles
695
00:39:11,816 --> 00:39:15,485
of organic gunk
called hydrocarbons.
696
00:39:15,487 --> 00:39:20,424
�
697
00:39:20,426 --> 00:39:25,629
these organic dunes contain
the building blocks of life.
698
00:39:25,631 --> 00:39:31,501
For scientists,
this is a tantalizing hint.
699
00:39:31,503 --> 00:39:34,170
Could titan harbor life?
700
00:39:34,172 --> 00:39:37,740
�
701
00:39:37,742 --> 00:39:40,110
stricker: Here on earth,
there's life that exists
702
00:39:40,112 --> 00:39:42,378
in so many extreme environments,
703
00:39:42,380 --> 00:39:45,515
so its not impossible
to think that life
704
00:39:45,517 --> 00:39:47,851
could have evolved
to use the methane
705
00:39:47,853 --> 00:39:50,854
and all of the other
chemical constituents on titan.
706
00:39:50,856 --> 00:39:55,058
If life has developed on titan,
it's going to look really weird.
707
00:39:55,060 --> 00:39:58,461
It's going to be really
different from life on earth.
708
00:39:58,463 --> 00:40:00,330
Thaller: To me, there's going to
be this wonderful moment
709
00:40:00,332 --> 00:40:02,199
in history
when we really do have
710
00:40:02,201 --> 00:40:04,667
another example
of how life can be,
711
00:40:04,669 --> 00:40:06,603
and if I had to place
my bets on it,
712
00:40:06,605 --> 00:40:10,540
I think we're going to find it
in the saturn system.
713
00:40:10,542 --> 00:40:13,810
Narrator: But cassini's
discovery of potential life
714
00:40:13,812 --> 00:40:17,614
sentenced the probe to death.
715
00:40:17,616 --> 00:40:21,084
Porco: We didn't want to leave
it just indefinitely in orbit
716
00:40:21,086 --> 00:40:24,354
because there's this fear
that, you know,
717
00:40:24,356 --> 00:40:27,691
should there be any earthly
contamination on the spacecraft,
718
00:40:27,693 --> 00:40:31,094
you don't want it crashing
into titan or enceladus.
719
00:40:31,096 --> 00:40:33,563
�
720
00:40:33,565 --> 00:40:39,102
narrator: Cassini interacted
with titan one last time.
721
00:40:39,104 --> 00:40:42,038
Spilker: With a gentle nudge
from titan's gravity,
722
00:40:42,040 --> 00:40:45,241
we call it titan's goodbye kiss.
723
00:40:45,243 --> 00:40:50,446
We ended the mission with a
plunge into saturn's atmosphere,
724
00:40:50,448 --> 00:40:54,918
vaporizing cassini and saying
goodbye to our friend.
725
00:40:54,920 --> 00:40:59,122
�
726
00:40:59,124 --> 00:41:03,326
Mitchell: I hope you're all as deeply proud
727
00:41:03,328 --> 00:41:06,129
of this amazing accomplishment.
728
00:41:06,131 --> 00:41:08,999
I'm going to call this the end of mission.
729
00:41:09,001 --> 00:41:11,535
Project manager Bob Mitchell.
730
00:41:13,605 --> 00:41:19,342
�
731
00:41:19,344 --> 00:41:24,480
narrator: Although cassini
is gone, its legacy lives on.
732
00:41:24,482 --> 00:41:26,750
Spilker:
Now we're sifting through
733
00:41:26,752 --> 00:41:31,154
all of the data collected,
still finding discoveries,
734
00:41:31,156 --> 00:41:34,757
putting together the pieces
of the puzzle to understand
735
00:41:34,759 --> 00:41:37,294
saturn, the rings,
and the moons.
736
00:41:37,296 --> 00:41:40,364
Porco: Cassini is going to
go down in history
737
00:41:40,366 --> 00:41:42,766
as one of the most
scientifically productive
738
00:41:42,768 --> 00:41:48,171
interplanetary missions
that humanity has ever flown.
739
00:41:48,173 --> 00:41:53,709
I'm immensely proud
and feel enormously privileged
740
00:41:53,711 --> 00:41:55,378
to have been a part of it.
741
00:41:55,380 --> 00:42:02,319
�
742
00:42:02,321 --> 00:42:06,656
plait: Besides the amazing
science cassini returned,
743
00:42:06,658 --> 00:42:09,326
just the beauty
of this planet
744
00:42:09,328 --> 00:42:13,196
I think sparked something
inside of us.
745
00:42:13,198 --> 00:42:15,131
Spilker: Whenever I look up
at saturn now,
746
00:42:15,133 --> 00:42:17,734
I know that cassini
is there, too,
747
00:42:17,736 --> 00:42:21,805
and so saturn is even
a more special place.
748
00:42:21,807 --> 00:42:28,345
�
59660
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