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Strangers from afar.
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Where might these come from?
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These aliens.
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This sculpture studio
makes models of aliens
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for the movies.
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The creatures crafted here have appeared
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in over 20 Hollywood films.
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But extraterrestrial life isn't something
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that just exists in the movies.
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I think it is, without doubt in my mind,
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that life has originated elsewhere.
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Whole rest of me is screaming
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that the universe is
probably teeming with life.
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Surely life exists in environments
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completely different from Earth's.
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As space exploration proceeds,
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scientists are growing more confident
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as to how they envision alien life.
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But what makes these scientists so sure
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that life does in fact
exist in outer space?
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The answer must be sought
on the cosmic front.
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Is our existence in this universe
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an isolated phenomenon?
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Or is space, in fact, teeming with life?
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For answers, scientists
are placing great hopes
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on one of the moons of a
planet far, far away.
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More than a billion kilometers from Earth
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lies the planet Saturn.
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Hidden amidst its rings,
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is a moon with good prospects
of harboring life.
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Here's a backlit view of Saturn.
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Beyond its familiar set of rings
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is an outer ring that
is thinner and fainter.
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The E Ring, discovered in 1967.
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The blueish-white E Ring includes
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one extremely significant
body circling Saturn.
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Enceladus, one of Saturn's many moons.
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Diameter, 500 kilometers.
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Its bright white color comes from ice.
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Enceladus appears to be covered in it.
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This image of Enceladus was taken
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by the Voyager II spacecraft in the 1980s.
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Seeing it, many scientists were astonished.
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The moon's surface is remarkably smooth.
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The elimination of craters in some areas
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suggests massively
transformative tectonic events.
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Could it be that whatever
is happening on Enceladus
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has something to do with the E Ring?
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As we shall see, the very human
desire to solve this riddle
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leads us to place great
hopes on the existence
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of extraterrestrial life.
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And lift off of the Cassini spacecraft
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on a 1,000,000,000 mile trek to Saturn.
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The Cassini Saturn probe
left Earth in 1997.
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Its primary mission, to
examine the relationship
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between Enceladus and the E Ring.
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Cassini's voyage to
Saturn took seven years.
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It reached the planet's vicinity in 2004.
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A quarter century after
the Voyager mission,
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the mysteries of Enceladus
are finally being addressed.
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In the western American state of Colorado
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is located the Cassini Imaging Labroratory.
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Here is where the imaging data
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collected by the Cassini
probe are analyzed.
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The leader of the imaging
team is Carolyn Porco.
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She says that starting with
Cassini's very first image,
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as it approached Enceladus,
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she was filled with astonishment.
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This was it.
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Enceladus appears darkly
in this backlit image.
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Some might think the image anti-climactic,
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but Porco deliberately
chose this backlit mode.
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Some suggestions were that there
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might actually be geysers,
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there might be little
volcanic kind of geysers
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coming off the surface of Enceladus,
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spewing tiny ice particles
into orbit around Saturn
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and forming the E Ring.
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We, in fact, had planned
our sequences of images
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to include observations where we're looking
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in the direction of the sun,
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so that if there was a plume
of very tiny particles
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we would be able to see it.
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Here's an example of back-lighting
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using a humidifier.
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We create a fine mist, normally invisible.
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But if we then shine a
light on it from behind...
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the mist becomes clearly visible.
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This backlit effect was precisely
what Porco had intended.
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Let's return to that first Cassini image.
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If we look closely at the
south pole of Enceladus,
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we see what Porco had been hoping to see,
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a conspicuously bright portion.
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A month later, a backlit Enceladus
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was photographed once again.
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In the same location,
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one could clearly make
out filaments of light,
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a plume being sent from
Enceladus into space.
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Analysis of the images revealed
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that this plume extended
more than 100 kilometers.
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What really, I think, made everybody
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just stand back in awe,
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was the magnitude of this phenomenon.
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July 14th, Cassini began a
major phase of research.
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Reducing altitude to 168 kilometers,
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it made detailed
observations of the terrain
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near the south pole of Enceladus.
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The mysterious moon then displayed features
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that even Porco had not anticipated.
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A number of vertical blue streaks.
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No craters at all, just this
series of parallel fractures
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stretching for 130 kilometers.
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The anticipated volcanic
topography was not present,
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but it was equally clear that the area
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had seen robust geological change.
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It looks totally different, unique.
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Not only did the imaging team
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get this incredible look at this region
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that no one had ever really seen before,
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which is the south pole of Enceladus,
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and not only did we find that
it was geologically unique,
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it was characterized by
this set of fractures,
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and was crater free, very bright.
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The team called the blue
streaks Tiger Stripes.
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The tectonic activity across this area
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was indicated also by the
surface temperatures.
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The average on Enceladus is
minus 200 degrees Celsius.
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00:10:04,979 --> 00:10:07,715
But the Tiger Stripe showed
a dramatic increase,
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to minus 80 degrees Celsius.
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Some researchers estimate
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that the highest portions of that area
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rise to minus 20 degrees.
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Furthermore, the nature of
the plume was revealed.
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Analysis of the data
showed it to be comprised
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mainly of ice and water vapor.
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Conclusive images were also recorded.
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Clearly, what had looked
like perhaps a single flare,
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actually incorporated more than a dozen
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individual jets or geysers.
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Moreover, the jets were issuing
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along the Tiger Stripe fractures.
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And the material they released into space
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has been forming one of Saturn's rings.
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The blueish-white E Ring is
thus a band of ice chunks,
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formed by high-volume eruptions
of ice from Enceladus.
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I keep calling it
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the Enceladus Interplanetary
Geyser Park, you know?
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That would be a great place,
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that would be one of the sight-seeing,
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top-10 sight-seeing locales
in the solar system.
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If we could actually land
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on the Tiger Stripes, we would
be able to see their jets
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ejecting ice and vapor
from the ice fissures
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at fearsome speed, some
100 meters per second.
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Rising as high as 100 kilometers,
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they would present a thrilling spectacle.
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And many scientists have begun to believe
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that Enceladus must harbor life.
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Why do they think so?
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The Austrian Alps have an
elevation exceeding 3,000 meters.
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Near their summits lie glaciers.
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One scientist thinks that this area
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bears a striking resemblance
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to the Tiger Stripes of Enceladus.
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Richard Hoover is an
astrobiologist with NASA.
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This is a world of extreme cold,
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minus 15 degrees Celsius, even in daytime.
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An ice cave provides entry
to the inside of a glacier.
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Sunlight cannot reach into the ice cave.
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This is a world of
darkness, like Enceladus,
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which exists so far from its sun.
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10 minutes into the ice.
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A huge space opens up.
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Ah, it's incredible.
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Fantastic.
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Ah, this is absolutely magnificent.
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This has been dubbed the Ice Palace.
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Huge columns of ice.
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Hoover posits that the Tiger
Stripe area on Enceladus
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must look like this.
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The spectacular ice
stalactites hanging down
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from the surface and from the walls.
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These kinds of formations
may actually be occurring
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in the Tiger Stripes of Enceladus also,
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where the ice crystals are forming,
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and then, under the gravitational field,
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falling inward toward the
center within the crevasses
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of these magnificent Tiger Stripes.
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One sees no plants here, no animals,
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merely a world of extreme
cold, a world of ice.
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It might appear that no life
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could exist in such an environment.
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But Hoover thinks differently.
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He extracts an ice core
and carefully bags it.
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The ice he brought back from the Ice Palace
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is melted in its hermetically
sealed bag, and then analyzed.
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First step, microscopic examination.
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Nice motility.
199
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Wonderful.
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Blinking right here, this
is a bacteria swimming.
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You see? Yeah.
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Microorganisms living in a world of ice.
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Here, too, nothing but ice it had seemed.
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Yet there was life.
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In his lab, Hoover preserves samples of ice
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collected from around the world,
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including the South Pole and Iceland.
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He has found microorganisms
in all of these samples.
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00:16:34,670 --> 00:16:37,538
This image conveys the
fantastic capabilities
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00:16:37,539 --> 00:16:39,866
of these microbes.
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00:16:39,867 --> 00:16:42,846
The white images are microorganisms,
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the black background is the water.
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00:16:46,261 --> 00:16:48,729
The membranes covering
these creatures' cells
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00:16:48,730 --> 00:16:51,995
is made of material that
protects them from freezing.
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00:16:51,996 --> 00:16:53,836
Rather than freezing themselves,
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00:16:53,837 --> 00:16:55,953
they melt the surrounding ice.
217
00:17:00,460 --> 00:17:01,568
It has been confirmed
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00:17:01,569 --> 00:17:04,563
that there are certain forms
of life capable of existing
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00:17:04,564 --> 00:17:07,608
in a minus 40 degree Celsius environment.
220
00:17:09,801 --> 00:17:12,648
I believe it is very possible
that there could be life
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00:17:12,649 --> 00:17:14,685
in the Tiger Stripes of Enceladus.
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00:17:14,686 --> 00:17:17,651
They're much hotter than what
anyone believed possible,
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00:17:17,652 --> 00:17:20,145
and we now know that microorganisms
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00:17:20,146 --> 00:17:23,261
live in glacial ice all
over the planet Earth,
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00:17:23,262 --> 00:17:25,127
therefore there could be microorganisms
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00:17:25,128 --> 00:17:28,728
alive and thriving in the
Tiger Stripes of Enceladus.
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00:17:32,093 --> 00:17:34,801
Considering the sheer tenacity of life,
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00:17:34,802 --> 00:17:37,669
it could well exist on Enceladus, too.
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00:17:37,670 --> 00:17:40,391
Of that, Hoover is convinced.
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00:17:46,381 --> 00:17:47,905
Carolyn Porco, leader
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00:17:47,906 --> 00:17:50,555
of the Cassini Imaging Central Laboratory.
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00:17:53,079 --> 00:17:55,926
Porco believes that truly
potent conditions for life
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00:17:55,927 --> 00:17:59,163
are present under the ice
of the Tiger Stripes.
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00:18:01,270 --> 00:18:03,893
She thinks there's a large
body of water there
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00:18:03,894 --> 00:18:05,403
in its liquid state.
236
00:18:09,153 --> 00:18:12,314
Water, it's the reason
there's life on Earth.
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00:18:19,168 --> 00:18:22,089
Across our globe, all sorts of lifeforms
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00:18:22,090 --> 00:18:25,316
use water in all sorts of ways.
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00:18:29,311 --> 00:18:31,646
Porco is convinced a huge amount of water
240
00:18:31,647 --> 00:18:33,764
lies under the Tiger Stripes.
241
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This was about 153.
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Her conviction originated
243
00:18:45,328 --> 00:18:47,961
during analysis of the Cassini images,
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00:18:47,962 --> 00:18:51,752
when she noticed something
distinctive about the jets.
245
00:18:51,753 --> 00:18:53,193
And that's why it's clear.
246
00:18:53,194 --> 00:18:54,942
It's clear here, you can
see the extent of it,
247
00:18:54,943 --> 00:18:56,307
how big it is.
248
00:18:56,308 --> 00:18:58,276
What we're seeing in these
images of the jets,
249
00:18:58,277 --> 00:19:00,494
those are tiny ice particles,
250
00:19:00,495 --> 00:19:05,422
and we see so much of the solids,
251
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compared to the vapor
252
00:19:06,692 --> 00:19:08,398
that is detected by the other instruments,
253
00:19:08,399 --> 00:19:10,733
that the most plausible way to get that
254
00:19:10,734 --> 00:19:14,438
is from saying that the material
255
00:19:14,439 --> 00:19:16,128
starts out as a liquid
256
00:19:16,129 --> 00:19:18,919
and the liquid droplets eventually freeze
257
00:19:18,920 --> 00:19:20,919
and become the particles that we see.
258
00:19:22,951 --> 00:19:24,423
Measurements show the diameter
259
00:19:24,424 --> 00:19:28,041
of the particles to be less
than 1/100th of a millimeter.
260
00:19:31,386 --> 00:19:32,931
If these geysers were shooting out
261
00:19:32,932 --> 00:19:35,556
only broken-up bits of surface ice,
262
00:19:35,557 --> 00:19:38,148
it is difficult to explain
how so many particles
263
00:19:38,149 --> 00:19:40,220
could become so small.
264
00:19:40,221 --> 00:19:42,323
But if it was water that was gushing up,
265
00:19:42,324 --> 00:19:45,060
freezing after the spray
had become droplets,
266
00:19:45,061 --> 00:19:48,927
then that would explain the large
quantity of ice particles.
267
00:19:52,453 --> 00:19:55,417
But Saturn, around which
Enceladus revolves,
268
00:19:55,418 --> 00:19:58,996
is one point four billion
kilometers from the sun.
269
00:19:58,997 --> 00:20:01,758
That's 10 times farther away than Earth.
270
00:20:03,298 --> 00:20:05,467
That's why the surface
temperature of Enceladus
271
00:20:05,468 --> 00:20:08,913
averages minus 200 degrees Celsius.
272
00:20:08,914 --> 00:20:12,027
Any water on it would freeze, becoming ice.
273
00:20:16,182 --> 00:20:17,994
On this moon of ice,
274
00:20:17,995 --> 00:20:21,616
how could a large body of water
exist in a liquid state?
275
00:20:26,059 --> 00:20:29,534
NASA's Jet Propulsion Laboratory, JPL,
276
00:20:29,535 --> 00:20:32,282
is located in the suburbs of Los Angeles.
277
00:20:35,338 --> 00:20:38,863
Inside is the control room
for the Cassini space probe.
278
00:20:42,293 --> 00:20:44,830
Today they are again instructing the probe,
279
00:20:44,831 --> 00:20:47,501
1,000,000,000 kilometers away, near Saturn.
280
00:20:48,585 --> 00:20:50,450
Recently, Cassini has uncovered facts
281
00:20:50,451 --> 00:20:52,786
supporting the theory that liquid water
282
00:20:52,787 --> 00:20:54,797
is present on Enceladus.
283
00:20:57,758 --> 00:21:02,193
In October of 2008, Cassini
drew very close to Enceladus
284
00:21:02,194 --> 00:21:04,290
on a low-altitude flyby.
285
00:21:07,496 --> 00:21:10,215
It was able to pass through the jets,
286
00:21:10,216 --> 00:21:13,313
and to analyze their
constituent matter minutely.
287
00:21:17,138 --> 00:21:20,076
One thing detected in the jets was ammonia.
288
00:21:26,183 --> 00:21:28,357
If ammonia is dissolved in water,
289
00:21:28,358 --> 00:21:31,163
it permits the water to
maintain its liquid state
290
00:21:31,164 --> 00:21:35,722
even in temperatures as low
as minus 97 degrees Celsius.
291
00:21:35,723 --> 00:21:38,887
In other words, it
functions like antifreeze.
292
00:21:41,965 --> 00:21:43,404
But there is another factor
293
00:21:43,405 --> 00:21:45,875
melting the ice on this frigid moon.
294
00:21:51,500 --> 00:21:55,324
The movements of another
of Saturn's moons, Dione.
295
00:22:05,356 --> 00:22:08,171
Enceladus revolves around
Saturn on an orbit
296
00:22:08,172 --> 00:22:11,011
in-between Saturn and Dione.
297
00:22:11,012 --> 00:22:14,918
Enceladus completes one
orbit every 33 hours.
298
00:22:14,919 --> 00:22:17,697
It takes Dione exactly twice as long,
299
00:22:17,698 --> 00:22:20,754
66 hours, to complete its own circuit.
300
00:22:21,986 --> 00:22:26,858
As a result, once every 66 hours,
301
00:22:26,859 --> 00:22:31,163
Saturn, Enceladus, and
Dione are all lined up.
302
00:22:31,164 --> 00:22:34,412
Subjected to the gravitational
pulls of both these bodies,
303
00:22:34,413 --> 00:22:36,235
the spherical shape of Enceladus
304
00:22:36,236 --> 00:22:38,747
is distorted into an ellipsoid.
305
00:22:40,769 --> 00:22:42,901
Then, as the alignment breaks up,
306
00:22:42,902 --> 00:22:45,147
Enceladus reverts to a sphere.
307
00:22:51,947 --> 00:22:53,855
When this happens enough times,
308
00:22:53,856 --> 00:22:56,010
the interior of Enceladus experiences
309
00:22:56,011 --> 00:22:58,149
a build-up of frictional heat.
310
00:23:00,319 --> 00:23:02,769
That melts some of the ice in the crust.
311
00:23:02,770 --> 00:23:04,739
It turns into liquid water.
312
00:23:07,070 --> 00:23:09,000
The hypothesis is that then,
313
00:23:09,001 --> 00:23:10,994
as the surrounding ice fractures,
314
00:23:10,995 --> 00:23:13,443
the water gushes out in jets.
315
00:23:15,870 --> 00:23:19,282
May be a body of liquid under
the surface of Enceladus,
316
00:23:19,283 --> 00:23:23,911
so the jets are an
indication to us actually
317
00:23:23,912 --> 00:23:25,308
that we have on Enceladus
318
00:23:25,309 --> 00:23:27,875
a place where life might
have gotten started.
319
00:23:31,560 --> 00:23:34,630
An ocean under the ice of Enceladus,
320
00:23:34,631 --> 00:23:37,385
nurturing diverse forms of life.
321
00:23:37,386 --> 00:23:40,063
That's the vision of
another scientist as well.
322
00:23:43,024 --> 00:23:47,178
Yasuhito Sekine is a scientist
at the University of Tokyo.
323
00:23:50,299 --> 00:23:51,886
He believes that the warm environment
324
00:23:51,887 --> 00:23:55,646
of this ocean under the ice
serves as a cradle of life.
325
00:24:14,095 --> 00:24:16,146
Such gravitational distortions
326
00:24:16,147 --> 00:24:18,125
have huge consequences.
327
00:24:20,115 --> 00:24:23,099
Sekine believes that not
just the icy crust,
328
00:24:23,100 --> 00:24:26,065
but the underlying rock
is affected as well,
329
00:24:26,066 --> 00:24:27,936
producing frictional heat.
330
00:24:34,332 --> 00:24:36,261
Actually, the kind of sea floor
331
00:24:36,262 --> 00:24:38,736
envisaged by Sekine for Enceladus
332
00:24:38,737 --> 00:24:41,494
has a close counterpart
right here on Earth.
333
00:24:45,308 --> 00:24:48,842
Here, the seabed is 1,500
meters below the surface.
334
00:24:52,049 --> 00:24:54,083
Volcanic activity expels water
335
00:24:54,084 --> 00:24:56,480
heated to 300 degrees Celsius.
336
00:24:57,861 --> 00:25:00,266
These are called hydrothermal vents.
337
00:25:04,933 --> 00:25:06,499
Here in a world of darkness
338
00:25:06,500 --> 00:25:08,772
beyond the reach of the sun's rays,
339
00:25:08,773 --> 00:25:12,584
hydrothermal energy nourishes
a variety of lifeforms.
340
00:25:15,097 --> 00:25:18,265
Sekine hypothesizes that Enceladus, too,
341
00:25:18,266 --> 00:25:20,461
has an environment like this.
342
00:25:20,462 --> 00:25:23,419
One that gives rise to
a distinct ecosystem.
343
00:25:29,708 --> 00:25:33,931
In 2009, Cassini observation
data were announced,
344
00:25:33,932 --> 00:25:37,435
data that apparently supported
Sekine's hypothesis.
345
00:25:41,249 --> 00:25:43,455
An article in the science journal, Nature,
346
00:25:43,456 --> 00:25:46,735
detailed the elements composing
the jets of Enceladus.
347
00:25:49,920 --> 00:25:52,926
This graph compare the
constituents of comets,
348
00:25:52,927 --> 00:25:55,625
which are thought to contain
the ingredients of planets,
349
00:25:55,626 --> 00:25:58,318
with the constituents of
the jets of Enceladus.
350
00:26:00,767 --> 00:26:03,048
The amounts of methane, ammonia,
351
00:26:03,049 --> 00:26:05,508
and other constituents are similar.
352
00:26:08,413 --> 00:26:10,706
The article also pointed to the possibility
353
00:26:10,707 --> 00:26:15,335
of a constituent unique to Enceladus,
354
00:26:15,336 --> 00:26:16,984
molecular nitrogen.
355
00:26:20,521 --> 00:26:23,773
Sekine believed that the presence
of this molecular nitrogen
356
00:26:23,774 --> 00:26:26,477
proved the presence of hydrothermal vents.
357
00:26:48,536 --> 00:26:50,130
With help from the Japan Agency
358
00:26:50,131 --> 00:26:53,942
for Marine Earth Science and
Technolgy, Sekine experiments
359
00:26:53,943 --> 00:26:57,468
to see how Enceladus might
produce molecular nitrogen.
360
00:27:01,131 --> 00:27:04,165
He's already replicated the
composition of the jets.
361
00:27:06,827 --> 00:27:10,490
Basically water, carbon
dioxide, and ammonia.
362
00:27:13,792 --> 00:27:15,273
Those ingredients are then mixed
363
00:27:15,274 --> 00:27:17,561
with a common mineral, Olivene,
364
00:27:17,562 --> 00:27:19,520
to see what the reaction will be.
365
00:27:26,929 --> 00:27:28,558
The ocean in Enceladus is thought
366
00:27:28,559 --> 00:27:30,703
to be several kilometers deep,
367
00:27:30,704 --> 00:27:32,928
creating tremendous water pressure.
368
00:27:36,272 --> 00:27:39,001
That high pressure environment
is approximated here
369
00:27:39,002 --> 00:27:41,476
by using a special device to apply
370
00:27:41,477 --> 00:27:44,329
300 atmospheres of pressure to the mixture.
371
00:27:48,080 --> 00:27:51,043
The temperature is 300 degrees Celsius,
372
00:27:51,044 --> 00:27:53,897
about the same as Earth's
hydrothermal vents.
373
00:27:57,124 --> 00:27:59,539
Will molecular nitrogen be produced?
374
00:28:10,697 --> 00:28:13,337
It's been a week since
the experiment started.
375
00:28:20,018 --> 00:28:21,650
What has happened to the material
376
00:28:21,651 --> 00:28:23,697
subjected to this high temperature,
377
00:28:23,698 --> 00:28:25,633
high pressure environment?
378
00:28:30,022 --> 00:28:32,567
Finally, the component analysis.
379
00:28:46,672 --> 00:28:48,422
Molecular nitrogen,
380
00:28:48,423 --> 00:28:50,784
the same component found by Cassini.
381
00:29:17,370 --> 00:29:19,299
Molecular nitrogen is generated
382
00:29:19,300 --> 00:29:22,110
by the decomposition of ammonia molecules.
383
00:29:23,301 --> 00:29:25,401
Ordinarily, ammonia is a substance
384
00:29:25,402 --> 00:29:28,148
that does not decompose
at low temperatures.
385
00:29:29,422 --> 00:29:31,396
The presence of molecular nitrogen
386
00:29:31,397 --> 00:29:34,067
indicates a high temperature environment.
387
00:29:36,111 --> 00:29:38,531
The hidden high temperature, high pressure
388
00:29:38,532 --> 00:29:40,863
deep-sea world on Enceladus.
389
00:29:41,859 --> 00:29:45,338
Lifeforms that can survive in
similarly harsh environments
390
00:29:45,339 --> 00:29:47,623
have been found here on Earth.
391
00:29:50,013 --> 00:29:52,231
They were discovered at hydrothermal vents
392
00:29:52,232 --> 00:29:53,900
in the Indian Ocean.
393
00:30:01,771 --> 00:30:03,358
They can survive in temperatures
394
00:30:03,359 --> 00:30:07,032
reaching as high as 122 degrees Celsius.
395
00:30:09,481 --> 00:30:11,710
Thermophilic methanogens are bacteria
396
00:30:11,711 --> 00:30:13,587
that thrive in high temperature,
397
00:30:13,588 --> 00:30:15,193
high pressure water.
398
00:30:33,254 --> 00:30:35,044
In fact, this experiment
399
00:30:35,045 --> 00:30:37,927
confirmed the production
of molecular hydrogen,
400
00:30:37,928 --> 00:30:40,215
the energy source for methanogens.
401
00:30:43,238 --> 00:30:46,811
If organisms like methanogens
exist on Enceladus,
402
00:30:46,812 --> 00:30:48,794
then hopes rise that this could lead
403
00:30:48,795 --> 00:30:51,243
to a world of diverse lifeforms.
404
00:31:15,141 --> 00:31:18,149
Enceladus is one point
four billion kilometers
405
00:31:18,150 --> 00:31:19,337
from the sun.
406
00:31:21,338 --> 00:31:24,618
Under its icy surface is an ocean of water.
407
00:31:29,040 --> 00:31:31,928
On that ocean's floor, hydrothermal vents
408
00:31:31,929 --> 00:31:33,886
similar to those on Earth.
409
00:31:35,822 --> 00:31:37,773
Fostering a rich ecosystem,
410
00:31:37,774 --> 00:31:40,958
based on lifeforms similar to methanogens.
411
00:31:42,552 --> 00:31:45,629
That's how Sekine pictures Enceladus.
412
00:31:51,907 --> 00:31:54,951
The clue was provided by
the jets of Enceladus.
413
00:32:00,109 --> 00:32:02,198
And that faint outer ring of light
414
00:32:02,199 --> 00:32:04,417
in which Enceladus is situated
415
00:32:04,418 --> 00:32:06,422
reflects our shining hope
416
00:32:06,423 --> 00:32:09,362
that we are not alone in the universe.
417
00:32:31,262 --> 00:32:34,001
That was October, 2010.
418
00:32:34,002 --> 00:32:36,252
This stunning news of an Earth-like planet
419
00:32:36,253 --> 00:32:38,493
that might be able to sustain life
420
00:32:38,494 --> 00:32:40,770
reverberated around the world.
421
00:32:46,194 --> 00:32:48,998
A planet like our own planet Earth,
422
00:32:48,999 --> 00:32:51,115
one on which life could exist.
423
00:32:54,194 --> 00:32:57,563
The discovery was made from
the volcanic island of Hawaii
424
00:32:57,564 --> 00:32:59,200
in the Pacific Ocean.
425
00:33:02,524 --> 00:33:05,167
Mauna Kea, an inactive volcano,
426
00:33:05,168 --> 00:33:08,350
has an elevation of 4,200 meters.
427
00:33:08,351 --> 00:33:11,264
On its summit are perched
astronomical observatories
428
00:33:11,265 --> 00:33:13,931
operated by the United States, Japan,
429
00:33:13,932 --> 00:33:15,888
France, and other countries.
430
00:33:19,978 --> 00:33:21,615
The Keck Observatory.
431
00:33:25,323 --> 00:33:27,882
Scientists used one of
the Keck's telescopes,
432
00:33:27,883 --> 00:33:29,738
whose 10 meter aperture classes it
433
00:33:29,739 --> 00:33:31,582
among the largest in the world,
434
00:33:31,583 --> 00:33:33,178
to make the discovery.
435
00:33:35,828 --> 00:33:37,396
Steven Vogt is a professor
436
00:33:37,397 --> 00:33:40,814
at the University of
California's Santa Cruz campus.
437
00:33:41,931 --> 00:33:43,198
He's part of the team that found
438
00:33:43,199 --> 00:33:45,399
a planet that may support life.
439
00:33:48,136 --> 00:33:50,045
So this is the Keck One telescope.
440
00:33:50,046 --> 00:33:52,348
This is where I do my planet hunting.
441
00:33:52,349 --> 00:33:54,663
Glises 581g is a very special planet.
442
00:33:54,664 --> 00:33:56,898
It reminds us the most of our own Earth.
443
00:33:58,280 --> 00:34:01,755
This very special planet
that Vogt discovered,
444
00:34:01,756 --> 00:34:03,990
what sort of planetary body is it?
445
00:34:05,426 --> 00:34:08,969
The night sky is punctuated
with points of light.
446
00:34:08,970 --> 00:34:12,581
Most are fixed stars
outside our solar system,
447
00:34:12,582 --> 00:34:15,882
each shining with its own
light, like our own sun.
448
00:34:18,674 --> 00:34:23,141
One of them is this reddish
star, 20 light-years away.
449
00:34:23,142 --> 00:34:25,610
That means it takes 20 years
at the speed of light
450
00:34:25,611 --> 00:34:27,566
for its image to reach Earth.
451
00:34:32,702 --> 00:34:35,852
It's only about 1/3 the
size of our own sun.
452
00:34:40,007 --> 00:34:42,968
The planet that Vogt
discovered orbits this star.
453
00:34:47,101 --> 00:34:50,437
Since 1998, Vogt has
worked with Paul Butler
454
00:34:50,438 --> 00:34:52,827
of the Carnegie Institution for Science
455
00:34:52,828 --> 00:34:54,731
to observe this red star.
456
00:34:59,836 --> 00:35:03,398
The discovery of a life-supporting
planet orbiting this star
457
00:35:03,399 --> 00:35:07,137
resulted from more than a decade
of scientific observations.
458
00:35:13,371 --> 00:35:15,413
And then, there it was.
459
00:35:19,258 --> 00:35:23,513
A planet they designated Gliese 581g.
460
00:35:23,514 --> 00:35:25,765
Triple the mass of the Earth.
461
00:35:25,766 --> 00:35:27,791
In orbit around its central star
462
00:35:27,792 --> 00:35:30,729
at a distance of 22,000,000 kilometers.
463
00:35:32,646 --> 00:35:34,792
That distance is significant.
464
00:35:38,276 --> 00:35:41,535
To understand why, consider our own sun.
465
00:35:43,055 --> 00:35:46,987
And consider liquid water,
the source of life.
466
00:35:46,988 --> 00:35:49,450
If a planet is too close
to its parent star,
467
00:35:49,451 --> 00:35:52,105
any water on it will evaporate,
468
00:35:52,106 --> 00:35:55,108
but if it's too far away,
the water will freeze.
469
00:35:57,983 --> 00:36:00,702
For water to remain on
the surface of a planet,
470
00:36:00,703 --> 00:36:02,472
it needs to orbit its parent star
471
00:36:02,473 --> 00:36:05,732
at just the right distance,
like planet Earth.
472
00:36:10,643 --> 00:36:13,991
The vicinity in which water can
remain on a planet's surface
473
00:36:13,992 --> 00:36:15,971
is called the habitable zone.
474
00:36:19,273 --> 00:36:20,668
When Vogt tried to calculate
475
00:36:20,669 --> 00:36:22,568
whether or not the planet he discovered
476
00:36:22,569 --> 00:36:24,616
was inside a habitable zone,
477
00:36:24,617 --> 00:36:27,095
he determined that it was
right in the middle of it.
478
00:36:28,275 --> 00:36:31,309
It was indeed a planet
very much like Earth.
479
00:36:38,282 --> 00:36:41,257
So the feeling of finding the first
480
00:36:41,258 --> 00:36:45,334
known planet that could
support liquid water
481
00:36:45,335 --> 00:36:47,692
is a great feeling and was very exciting.
482
00:36:47,693 --> 00:36:50,826
We'd been trying to do this for 15 years,
483
00:36:50,827 --> 00:36:52,970
so this is, for us, this is the end
484
00:36:52,971 --> 00:36:56,202
of a long journey in that respect.
485
00:36:56,203 --> 00:36:57,915
So it's a wonderful feeling.
486
00:36:59,190 --> 00:37:01,951
At long last, the discovery of a planet
487
00:37:01,952 --> 00:37:04,752
that might have liquid
water on its surface.
488
00:37:06,069 --> 00:37:09,535
However, even with present
observation technologies,
489
00:37:09,536 --> 00:37:11,541
the best we can do is to estimate
490
00:37:11,542 --> 00:37:13,861
the planet's mass and location.
491
00:37:16,618 --> 00:37:19,017
The presence of liquid water on the surface
492
00:37:19,018 --> 00:37:21,828
cannot be confirmed by direct observation.
493
00:37:27,348 --> 00:37:31,061
Is there really water on Gliese 581g?
494
00:37:31,062 --> 00:37:34,179
One researcher is trying
to settle this question
495
00:37:34,180 --> 00:37:35,486
using theory.
496
00:37:43,818 --> 00:37:47,689
Professor Shigeru Ida of the
Tokyo Institute of Technology
497
00:37:47,690 --> 00:37:51,352
is using computer simulations
to study planet formation.
498
00:37:55,700 --> 00:37:57,446
To look into the question of whether or not
499
00:37:57,447 --> 00:38:00,657
water is present on Gliese 581g,
500
00:38:00,658 --> 00:38:03,495
Ida has studied what types
of planets can be formed
501
00:38:03,496 --> 00:38:05,539
by a central red dwarf star.
502
00:38:12,806 --> 00:38:16,358
Planets originate from clouds
of cosmic dust and gas
503
00:38:16,359 --> 00:38:18,267
that group around a central star
504
00:38:18,268 --> 00:38:20,108
at the time of its own birth.
505
00:38:27,069 --> 00:38:29,766
As these dusts and gases coalesce,
506
00:38:29,767 --> 00:38:33,408
they eventually form
larger bodies, planets.
507
00:38:37,328 --> 00:38:39,909
Ida has run 3,000 permutations
508
00:38:39,910 --> 00:38:42,436
to see what sorts of
planets might originate
509
00:38:42,437 --> 00:38:45,588
from varying amounts of
the same dusts and gases.
510
00:38:48,123 --> 00:38:49,610
These are the results.
511
00:38:52,550 --> 00:38:54,868
Each dot represents a planet.
512
00:38:54,869 --> 00:38:57,839
The colors indicate what the
different planets are made of.
513
00:39:02,645 --> 00:39:05,610
Green means that the main
constituent is rock,
514
00:39:05,611 --> 00:39:07,043
as with planet Earth.
515
00:39:08,373 --> 00:39:10,570
Red means a planet such as Saturn,
516
00:39:10,571 --> 00:39:12,646
composed primarily of gases.
517
00:39:13,761 --> 00:39:15,848
And blue indicates that
the planet is made up
518
00:39:15,849 --> 00:39:18,532
mostly of ice, like Neptune.
519
00:39:22,271 --> 00:39:25,799
Vogt's observations put
the mass of Gliese 581g
520
00:39:25,800 --> 00:39:27,795
at triple that of Earth's,
521
00:39:27,796 --> 00:39:31,799
and its distance from its star
at 22,000,000 kilometers.
522
00:39:54,116 --> 00:39:56,984
In other words, Gliese 581g
523
00:39:56,985 --> 00:40:00,604
is not, like planet Earth,
composed primarily of rock.
524
00:40:02,849 --> 00:40:06,086
Rather, it's an ice planet, like Neptune.
525
00:40:10,230 --> 00:40:12,300
And yet one can still have high hopes
526
00:40:12,301 --> 00:40:14,151
that life does exist there.
527
00:40:31,700 --> 00:40:34,133
Ida believes that Gliese 581g
528
00:40:34,134 --> 00:40:36,714
was born as an ice planet in a cold region
529
00:40:36,715 --> 00:40:38,553
far from its parent star.
530
00:40:43,337 --> 00:40:46,280
In the course of tens of
thousands of revolutions,
531
00:40:46,281 --> 00:40:48,296
it gradually drew closer,
532
00:40:48,297 --> 00:40:50,702
winding up in the middle
of the habitable zone.
533
00:40:54,633 --> 00:40:57,128
The result was that the surface ice melted,
534
00:40:57,129 --> 00:41:00,674
becoming liquid water,
creating an ocean planet.
535
00:41:04,446 --> 00:41:06,716
The amount of water on such an ocean planet
536
00:41:06,717 --> 00:41:09,549
would be quite different from
what it is on our own planet.
537
00:41:11,965 --> 00:41:13,761
Look at a cross-section of Earth.
538
00:41:16,414 --> 00:41:18,711
It's made almost entirely of rock.
539
00:41:23,240 --> 00:41:26,160
The oceans make up just 2/100 of a percent
540
00:41:26,161 --> 00:41:29,419
of the total mass, a very thin layer.
541
00:41:31,420 --> 00:41:33,836
Gliese 581g is different.
542
00:41:37,170 --> 00:41:39,065
It's primarily water.
543
00:41:41,105 --> 00:41:45,431
In fact, water makes up over
50% of the planet's mass.
544
00:41:50,247 --> 00:41:54,363
The first planet ever to be
discovered in a habitable zone,
545
00:41:54,364 --> 00:41:56,406
Gliese 581g.
546
00:42:02,353 --> 00:42:04,667
With a high probability of maintaining
547
00:42:04,668 --> 00:42:06,944
vast amounts of liquid water.
548
00:42:11,963 --> 00:42:15,925
Oceans bathed in the sunset-like
glow of its red star.
549
00:42:21,446 --> 00:42:24,383
What sorts of lifeforms
might we find there?
550
00:42:30,629 --> 00:42:32,398
What does a biologist have to say
551
00:42:32,399 --> 00:42:35,705
about life on Gliese 581g,
552
00:42:35,706 --> 00:42:38,054
an exoplanet outside our solar system?
553
00:42:41,946 --> 00:42:43,657
Takeshi Naganuma.
554
00:42:45,380 --> 00:42:47,715
He studies lifeforms in
extreme environments
555
00:42:47,716 --> 00:42:49,790
like volcanoes and deserts.
556
00:42:52,025 --> 00:42:53,560
Given the persistence of life
557
00:42:53,561 --> 00:42:56,717
in such extremely adverse
circumstances on Earth,
558
00:42:56,718 --> 00:42:59,955
he thinks extraterrestrial
life must also exist.
559
00:43:31,012 --> 00:43:32,585
One month after the announcement
560
00:43:32,586 --> 00:43:37,413
about Gliese 581g, Naganuma
is paying a visit to Ida.
561
00:43:40,458 --> 00:43:42,206
Naganuma is hoping to learn more about
562
00:43:42,207 --> 00:43:45,758
the environment on Gliese 581g,
563
00:43:45,759 --> 00:43:47,326
so that he can consider the question
564
00:43:47,327 --> 00:43:49,710
of life on that planet more deeply.
565
00:43:55,938 --> 00:43:58,775
Ida's first step, to
explain certain aspects
566
00:43:58,776 --> 00:44:01,510
of Gliese 581g's parent star.
567
00:44:04,482 --> 00:44:07,182
This brought up the question
of the star's lifespan.
568
00:44:14,142 --> 00:44:16,157
Indeed, 10,000,000,000 years
569
00:44:16,158 --> 00:44:19,497
would be more than double
the age of our own sun,
570
00:44:19,498 --> 00:44:22,467
which is only 4,600,000,000 years old.
571
00:44:24,371 --> 00:44:26,727
That would mean that Gliese 581g
572
00:44:26,728 --> 00:44:28,572
has had plenty of time to evolve
573
00:44:28,573 --> 00:44:30,530
complex forms of life.
574
00:44:32,840 --> 00:44:37,804
Ida says that Gliese 581g has
plenty of water, but no land.
575
00:44:42,493 --> 00:44:45,837
The only rock on this
planet lies deep within.
576
00:44:48,146 --> 00:44:49,628
With the ocean reaching depths
577
00:44:49,629 --> 00:44:51,922
of several thousand kilometers,
578
00:44:51,923 --> 00:44:55,446
there is no way that that
rock could form dry land.
579
00:44:56,956 --> 00:44:58,993
Learning that there is no land there
580
00:44:58,994 --> 00:45:02,023
has convinced Naganuma that
an Earth-like civilization
581
00:45:02,024 --> 00:45:04,161
could not develop on this planet.
582
00:45:07,846 --> 00:45:11,275
But the ocean would still be
teeming with life, he says.
583
00:45:15,185 --> 00:45:17,386
What form would that life take?
584
00:45:20,326 --> 00:45:24,122
Let's take a look at the
world of Gliese 581g
585
00:45:24,123 --> 00:45:26,751
as envisaged by Takeshi Naganuma.
586
00:45:31,802 --> 00:45:35,862
A vast ocean, no boundaries in sight.
587
00:45:35,863 --> 00:45:38,005
Within it, life.
588
00:45:42,820 --> 00:45:44,505
What are these?
589
00:45:44,506 --> 00:45:46,985
Creatures of Gliese 581g.
590
00:45:50,532 --> 00:45:53,923
They float near the surface,
living off the red light
591
00:45:53,924 --> 00:45:55,806
by means of photosynthesis.
592
00:45:57,807 --> 00:45:59,192
Their flat shape enables them
593
00:45:59,193 --> 00:46:01,640
to process as much light as possible.
594
00:46:04,206 --> 00:46:06,744
Life exists not only near the surface,
595
00:46:06,745 --> 00:46:09,065
but in the depths as well.
596
00:46:09,066 --> 00:46:11,508
These tube-like creatures are an example.
597
00:46:15,600 --> 00:46:17,507
They move by propulsion,
598
00:46:17,508 --> 00:46:19,544
taking water in with their mouths
599
00:46:19,545 --> 00:46:21,865
and expelling it from their rear ends.
600
00:46:25,337 --> 00:46:28,173
At the same time, they filter plankton,
601
00:46:28,174 --> 00:46:30,259
from which they derive nourishment.
602
00:46:34,520 --> 00:46:36,205
Their flexible bodies can adjust
603
00:46:36,206 --> 00:46:38,658
to variations in water pressure,
604
00:46:38,659 --> 00:46:41,196
enabling them to range from the deep sea
605
00:46:41,197 --> 00:46:42,919
to shallower waters.
606
00:46:48,472 --> 00:46:50,262
And there would be an unexpected place
607
00:46:50,263 --> 00:46:52,263
where life could develop as well.
608
00:47:00,215 --> 00:47:03,424
Surrounding a planet that is
triple the mass of the Earth,
609
00:47:03,425 --> 00:47:06,145
the atmosphere of Gliese 581g
610
00:47:06,146 --> 00:47:09,755
is estimated to be 100
times denser than Earth's.
611
00:47:15,094 --> 00:47:17,910
Naganuma points out that
such a thick atmosphere
612
00:47:17,911 --> 00:47:21,002
would, in sense, approximate a liquid,
613
00:47:21,003 --> 00:47:23,114
constituting a medium
through which creatures
614
00:47:23,115 --> 00:47:25,240
could easily float.
615
00:47:25,241 --> 00:47:28,069
So airborne creatures might emerge as well.
616
00:47:32,311 --> 00:47:36,212
Naganuma calls this particular
extraterrestrial lifeform
617
00:47:36,213 --> 00:47:37,435
Ballchutes.
618
00:47:42,283 --> 00:47:44,505
Three eyes and a large brain.
619
00:47:58,601 --> 00:48:00,733
What kind of life would they lead,
620
00:48:00,734 --> 00:48:02,627
these sky-borne aliens?
621
00:48:13,939 --> 00:48:17,340
This is the Gliese 581g sky
622
00:48:17,341 --> 00:48:19,613
and the lifeforms that dwell in it,
623
00:48:19,614 --> 00:48:22,081
as conceptualized by Naganuma.
624
00:48:23,677 --> 00:48:27,089
These ballchutes, short
for balloon parachutes,
625
00:48:27,090 --> 00:48:31,005
produce methane and other
light gases internally.
626
00:48:31,006 --> 00:48:32,688
By regulating the amount,
627
00:48:32,689 --> 00:48:34,031
they glide through the sky
628
00:48:34,032 --> 00:48:36,533
like hot air balloons above planet Earth.
629
00:48:38,032 --> 00:48:41,647
Or, by expanding their bodies
into the shape of an umbrella
630
00:48:41,648 --> 00:48:46,471
and then a parasol, they end their buoyancy
631
00:48:46,472 --> 00:48:49,466
and descend slowly, like parachutes.
632
00:48:53,196 --> 00:48:55,679
They negotiate the skies at will,
633
00:48:55,680 --> 00:48:58,831
using their large brains
and skillful bodies.
634
00:49:01,226 --> 00:49:03,273
But eyesight development helps evolve
635
00:49:03,274 --> 00:49:05,572
a totally different creature as well.
636
00:49:09,353 --> 00:49:13,049
One that puts its superior
eyesight to savage use.
637
00:49:25,054 --> 00:49:29,432
That's right, these new glider
creatures are carnivores.
638
00:49:33,427 --> 00:49:36,711
When they spot prey, they
go into a power dive
639
00:49:36,712 --> 00:49:39,405
and spear their victim
with their sharp jaws.
640
00:49:48,157 --> 00:49:50,182
Then they use their long tongues
641
00:49:50,183 --> 00:49:52,769
to suck out the brains of the ballchutes.
642
00:50:05,361 --> 00:50:09,968
A plausible view of life
and death on Gliese 581g,
643
00:50:09,969 --> 00:50:12,496
whose long-lived sun has given it time
644
00:50:12,497 --> 00:50:14,975
to evolve diverse lifeforms.
645
00:50:24,828 --> 00:50:26,873
Naganuma has concluded that life there
646
00:50:26,874 --> 00:50:29,570
would be dominated by big-brained creatures
647
00:50:29,571 --> 00:50:32,957
that one might as well call aliens.
648
00:51:00,558 --> 00:51:03,506
The universe is teeming with life.
649
00:51:03,507 --> 00:51:05,224
That's a premise that scientists
650
00:51:05,225 --> 00:51:07,724
are busy turning into a conviction.
651
00:51:09,654 --> 00:51:13,937
Steven Vogt, a co-discoverer
of Gliese 581g,
652
00:51:13,938 --> 00:51:17,815
is himself setting forth
on a new cosmic front.
653
00:51:19,165 --> 00:51:22,882
So this is the part of the
Automated Planet Finder.
654
00:51:25,618 --> 00:51:27,014
Vogt has developed a device
655
00:51:27,015 --> 00:51:31,211
to search for planets like
Gliese 581g automatically.
656
00:51:33,851 --> 00:51:36,080
You enter in the location of the fixed star
657
00:51:36,081 --> 00:51:38,705
near which you want to search for planets,
658
00:51:38,706 --> 00:51:41,983
and then it conducts the
survey for you automatically.
659
00:51:46,032 --> 00:51:47,076
It's being installed
660
00:51:47,077 --> 00:51:50,346
at the University of
California's Lick Observatory.
661
00:51:52,699 --> 00:51:56,420
The fixed star around which
Gliese 581g revolves
662
00:51:56,421 --> 00:51:58,474
is a red dwarf star.
663
00:51:58,475 --> 00:52:01,964
Such stars make up nearly
80% of the Milky Way.
664
00:52:07,442 --> 00:52:10,523
So Vogt is confident there
must be many more planets
665
00:52:10,524 --> 00:52:14,497
like Gliese 581g that are
capable of sustaining life.
666
00:52:20,988 --> 00:52:23,386
So my expectations for the APF
667
00:52:23,387 --> 00:52:27,290
are that we will find many
Earth-like or Earth-size planets
668
00:52:27,291 --> 00:52:29,977
capable of supporting life as we know it.
669
00:52:29,978 --> 00:52:32,431
There's probably tens of billions
670
00:52:32,432 --> 00:52:34,564
of such planets in our galaxy.
671
00:52:34,565 --> 00:52:38,201
And so we hope to find the
nearest ones with this facility.
672
00:52:38,202 --> 00:52:40,356
I know we'll find them.
673
00:52:40,357 --> 00:52:41,642
I'm certain of it.
674
00:52:43,380 --> 00:52:46,441
The universe is teeming with life.
675
00:52:46,442 --> 00:52:50,030
Someday that will be proved
by scientific observation.
676
00:52:52,991 --> 00:52:56,634
Vogt's passion will not permit
him to abandon that quest.
677
00:53:02,654 --> 00:53:04,765
The scientists on the cosmic front lines
678
00:53:04,766 --> 00:53:07,570
of space exploration have detected places
679
00:53:07,571 --> 00:53:11,048
both within our solar
system and far beyond it
680
00:53:11,049 --> 00:53:12,824
where life can exist.
681
00:53:23,581 --> 00:53:28,569
In space, worlds unfold beyond
our wildest imaginings.
682
00:53:28,570 --> 00:53:31,501
They are merely waiting
for us to discover them.
683
00:53:36,917 --> 00:53:39,210
Humankind has only just begun
684
00:53:39,211 --> 00:53:42,435
to challenge the cosmic front.
53531
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