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(intense music)
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- [Narrator] Billions of years ago,
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our nearest planetary neighbor, Venus,
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may have had oceans and rivers,
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life-giving habitats,
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like the ones that graced the early Earth.
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(dramatic music)
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(thunder rumbling)
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Today, it's burned-out surface
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is a global fossil of
volcanic destruction.
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(lava sloshing)
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Concealed beneath a
dense toxic atmosphere.
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(wind whooshing)
(soft dramatic music)
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Scientists are now unveiling
daring new strategies
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to explore its tortured landscapes,
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to search for clues from a
time when the planet was alive.
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How did Venus descend
into this hellish state?
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And how did our planet,
Earth, manage to survive?
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(mysterious music)
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(thunder rumbling)
(lightning clapping)
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(slow music)
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At the surface, the air
is 95% carbon dioxide.
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So dense, it's more like an
ocean than an atmosphere.
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And it's hot enough to melt lead.
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Overhead, thick clouds of sulfuric acid.
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(eerie music)
(thunder rumbling)
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No spacecraft has lasted
longer than two hours on Venus.
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(lightning clapping)
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All we have seen close up,
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a few images transmitted by
the Soviet Venera landers
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back in the 1970s.
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(mystical music)
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Radar images from the
Magellan Mission in the '90s
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have stoked our desire for more.
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- We think of it
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as this sort of ugly,
forbidding, scary place,
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because we've seen these
few Russian lander images
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of these sort of eroded rocks
and crushing atmosphere.
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But when you look at the Magellan imagery
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and you see this bewildering array
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of volcanic forms and flows
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and bizarre and interesting
canyons and valleys and channels
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that have been carved by liquid lava
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and volcanoes of different
sizes and shapes,
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I think the surface of Venus
is probably really beautiful.
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(mystical music)
(thunder rumbling)
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(dramatic music)
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- [Narrator] Thousands of years ago,
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Asian skywatchers saw Venus
as two separate stars.
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(speaking in foreign language),
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the Beginner of Brightness in the morning.
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And (speaking in foreign language),
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the Exalted Western One in the evening.
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- It's always sort of flirting
with the edges of night.
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You'll never see Venus at
midnight up high in the sky.
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It's always just in the
edges of dawn and dusk.
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- [Narrator] Sumerian priests
saw it as one, Inanna,
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goddess of sex, fertility,
physical beauty, and attraction.
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(woman singing in foreign language)
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Inanna became Aphrodite to the Greeks.
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Born from the foam of the sea,
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protector of those who sail,
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the Hellenic goddess of love
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beckoned us to venture into the unknown.
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(dramatic music)
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Roman leaders declared
April the month of Venus
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throughout the empire.
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During the festival of Veneralia,
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Romans honored purity and
piety and affairs of the heart.
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Across the Atlantic,
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Venus was seen as the
little brother of the sun.
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- In a way, the most
astute Venus observers
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were the Mesoamericans, the
Aztecs, the Maya, the Toltecs.
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For those cultures, Venus
was this male macho warrior
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with a spear going down
into the underworld
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and doing battle against
the enemies of humanity.
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(light music)
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We think of Venus as Botticelli's Venus,
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the feminine figure in our culture.
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But, around the world,
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Venus has had a lot of very
different manifestations.
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- [Narrator] In time, the Venus of myth
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gave way to the scrutiny of science.
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(soft upbeat music)
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In 1610, Galileo Galilei
observed crescent Venus
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changing through phases like the moon.
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Yet another clue that
planets orbit the sun.
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But even through his telescope,
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Galileo could not discern its features.
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Finally, in May 1761,
thanks to a rare alignment,
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the Russian astronomer, Mikhail Lomonosov,
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glimpsed its distinctive character.
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(shimmering music)
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- About once every 100 years or so,
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Venus actually passes in
between the sun and the Earth,
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and you can see that little dot of Venus
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moving across the face of the sun.
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(dramatic music)
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At the moment when the dot of Venus
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starts to cross the disk of the sun,
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the very first moment
and the very last moment
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when the dot of Venus moves
off the disk of the sun,
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something weird happens.
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There's a distortion, what
is called the black drop.
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(mystical music)
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It's almost like the edge of the sun
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kinda leaps off towards it,
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and then is distorted inwards.
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And Lomonosov realized
that that would make sense
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if Venus had an atmosphere.
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Once you know that,
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then you can deduce the diameter of Venus.
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And they said, "Oh, wow!
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"It's basically the same size as Earth.
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"It's the size of Earth,
and yet it's so bright.
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"Why is it so bright?
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"Oh, because it must
be covered in clouds."
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And they were right about that, as well.
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And the assumption at that
time, which was reasonable,
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was that the clouds are made out of water.
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(intense music)
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- [Narrator] The idea
that Venus was like Earth
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sparked the imaginations
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of fantasy and science fiction writers.
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(dramatic music)
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(singers vocalizing)
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- I remember seeing a
book when I was a kid
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that said that Venus might
have prehistoric jungles
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and dinosaur-type animals.
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I thought that would be really exciting,
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but turned out to be nothing like that.
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(engines roaring)
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- [Astronaut] (indistinct)
be advised, three.
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- [Dispatcher] 30 seconds,
this is programming, over.
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- [Narrator] At the dawn of the Space Age,
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Mariner 2 was the first successful mission
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to another planet.
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- Way back in 1962, Mariner
2 became the first spacecraft
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to explore Venus on a flyby.
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And it made a fantastic discovery
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that the Venus surface was very hot.
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Unfortunately, that was not
very good for Venus exploration
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because all the classical ideas
about Venus being habitable
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with people and forests
living on the surface
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just went out the door.
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(intense music)
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- [Narrator] Stranger still,
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NASA's Mariner 2 found that
the planet rotates very slowly
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and backwards compared to Earth.
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Americans celebrated the triumph.
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(soft music)
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Not to be out done,
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the Soviet Union attempted
at least 16 missions to Venus
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between 1961 and 1984.
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(air whooshing)
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December 1970, Venera 7 made
the first successful landing
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and the first transmission
of data from its surface.
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Nearly five years later,
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Venera 9 and Venera 10
captured the first images
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of Venus's tormented landscape.
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In December 1978,
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the American Pioneer Venus Orbiter
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began a 13-year radar mapping mission.
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It was followed by a
separate Pioneer MultiProbe
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dropped into the atmosphere.
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- [Dispatcher] Atlantis, Houston.
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Sunnyvale had a good direct check
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and their command is complete.
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- [Narrator] And a decade later,
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NASA's flagship, Magellan,
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was deployed from the Space Shuttle
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on an unusually long 15-month
journey inward to Venus.
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- [Command Control] Okay,
Peter, we copy checkout.
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(intense music)
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- [Narrator] Looping pole to
pole more than 4,000 times,
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Magellan's imaging radar
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mapped more than 97% of Venus's landforms.
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Among Magellan's findings,
the volcanic surface of Venus
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overlies a surprisingly thick crust.
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(mystical music)
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Remarkably, about three billion years ago,
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Venus was probably much more like Earth.
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(gas hissing)
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Each one nurtured the promise of life.
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(water bubbling)
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- They're the same size.
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They formed in roughly the same place.
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There's a lot of circumstantial evidence
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that Venus had a more
Earth-like environment
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when it was young.
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So they may have both had warm oceans
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and all the other conditions
necessary for an origin of life
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at the time when Earth
apparently had an origin of life.
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- Our biggest problem with Venus
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is that we have so little information
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about its ancient past.
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The surface of a planet,
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and to some extent the
atmosphere of a planet,
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are like a crime scene.
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Venus is the worst crime scene imaginable
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because it's been almost
completely disrupted over time.
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And the big question for those of us
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who are trying to study Venus
and understand its history
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is, when did Venus's
evolution really diverge
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from Earth's evolution?
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(mysterious music)
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- Venus and Earth are the twin planets.
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It's the only planet
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that is likely to be
still geologically active
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in some of the same ways as the Earth.
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It's really a huge laboratory
for understanding the Earth
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because of its many similarities,
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as well as some differences.
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(lava sloshing)
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- So Venus is kind of the
Earth's evil twin sister.
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It shows how two worlds of
similar size, similar density,
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not that far apart in terms
of distance to the sun,
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evolved very differently.
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(mysterious music)
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- [Narrator] Early on,
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Venus was on a path similar
to its sister planet, Earth.
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The radar data hold intriguing
clues to a watery past,
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including vast plateaus
made up of granite rocks
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that likely formed at
the bottom of an ocean.
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- There are areas on Venus
that look like continents.
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They're high-standing.
They're kinda wrinkly.
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They are also the oldest rocks on Venus
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because Venus has had this weird history
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where much of the surface is new.
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So these rocks are the only rocks
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from the first 80% of
the history of Venus.
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That's where we want to go.
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That's where I wanted
to go is to these areas,
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which are called tessera terrain
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because of their tile-like appearance.
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Whatever it is that spurred
the formation of life,
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in my mind, why wouldn't it
have happened everywhere?
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And that's the record
that we're looking for
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in the rocks of the tessera.
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Were there evidence of
ancient environments
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that would support life?
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(gas hissing)
(mystical music)
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(light music)
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- [Narrator] Venus is close to Earth
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in size, mass, and rocky composition,
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but that's where the similarities end.
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- Now, one thing we've learned in general
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about the formation of the planets
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is that the final stages
of planetary formation
250
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were characterized by a small number
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of really huge collisions.
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(planets sizzling)
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Those last few violent
collisions happened on Earth
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in just such a way as
to leave it with a moon
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and on Venus, through
a different combination
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of impact size and impact angles,
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it may have had been left with no moon,
258
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but with its very slow rotation.
259
00:15:47,840 --> 00:15:50,490
- [Narrator] Compared to our 24 hour day,
260
00:15:50,490 --> 00:15:53,430
it takes more than 243 Earth days
261
00:15:53,430 --> 00:15:56,090
for Venus to rotate just once,
262
00:15:56,090 --> 00:15:58,250
the longest day in the solar system.
263
00:15:59,540 --> 00:16:01,900
- And it rotates in
the opposite direction,
264
00:16:01,900 --> 00:16:03,960
so that if you were on
the surface of Venus
265
00:16:03,960 --> 00:16:05,180
and could see the sun,
266
00:16:05,180 --> 00:16:09,260
it would rise in the
west and set in the east.
267
00:16:09,259 --> 00:16:12,209
(light music)
268
00:16:12,210 --> 00:16:15,300
On Earth, the sun moves
along in the sunrise
269
00:16:15,300 --> 00:16:17,120
at hundreds of miles per hour.
270
00:16:17,120 --> 00:16:18,900
So you have to be up in a jet airplane
271
00:16:18,900 --> 00:16:21,280
if you wanted the sunset to last forever.
272
00:16:21,280 --> 00:16:25,080
On Venus though, it's four
or five miles per hour.
273
00:16:25,080 --> 00:16:27,990
So you could kind of
walk along at a good clip
274
00:16:27,990 --> 00:16:30,920
and keep the sunset going
275
00:16:30,920 --> 00:16:34,070
or the sunrise going
as long as you wanted.
276
00:16:34,070 --> 00:16:39,070
The pace of the planetary
rotation is a human walking pace.
277
00:16:41,090 --> 00:16:44,320
- [Narrator] Even that slow
pace may be winding down.
278
00:16:45,590 --> 00:16:47,810
- The very thick atmosphere of Venus
279
00:16:47,810 --> 00:16:50,300
is actually being pushed and pushing back
280
00:16:50,300 --> 00:16:51,340
from the typography
281
00:16:51,340 --> 00:16:53,500
and changing its rotation rate very slowly
282
00:16:53,500 --> 00:16:55,760
and very slightly over the decades.
283
00:16:55,760 --> 00:16:58,670
And that has been measured
by ground-based units
284
00:16:58,670 --> 00:17:00,770
and by Magellan, and
even by Venus Express,
285
00:17:00,770 --> 00:17:02,460
the most recent European mission.
286
00:17:02,461 --> 00:17:03,291
(wind whooshing)
287
00:17:03,294 --> 00:17:05,464
(mystical music)
288
00:17:05,460 --> 00:17:08,310
- [Narrator] Though the surface
creeps along without hurry,
289
00:17:08,310 --> 00:17:12,360
the clouds move quickly
and their speeds change.
290
00:17:15,550 --> 00:17:17,600
The Japanese Akatasuki probe,
291
00:17:17,600 --> 00:17:20,480
also known as the Venus Climate Orbiter,
292
00:17:20,480 --> 00:17:23,440
recently found that the
atmosphere spins much faster
293
00:17:23,440 --> 00:17:25,260
than the planet itself,
294
00:17:25,260 --> 00:17:27,820
a phenomenon called superrotation.
295
00:17:30,300 --> 00:17:32,790
This movement is driven by heat
296
00:17:32,790 --> 00:17:34,970
rising continually from the surface.
297
00:17:36,456 --> 00:17:37,336
(gentle music)
298
00:17:37,340 --> 00:17:40,060
Mysteriously, the planet
lacks a key feature
299
00:17:40,060 --> 00:17:42,170
that protects Earth and its atmosphere,
300
00:17:43,270 --> 00:17:45,800
a strong magnetic field.
301
00:17:45,800 --> 00:17:48,290
(intense music)
302
00:17:48,290 --> 00:17:50,450
Without this protective shield,
303
00:17:50,450 --> 00:17:52,930
intense ultraviolet rays from the sun
304
00:17:52,930 --> 00:17:55,910
split water molecules apart
in the high atmosphere.
305
00:17:58,900 --> 00:18:01,950
Then the sun's intense
stream of charged particles,
306
00:18:01,950 --> 00:18:06,170
the solar wind carries much of
the hydrogen away into space.
307
00:18:07,880 --> 00:18:10,510
- In the very early solar system,
308
00:18:10,510 --> 00:18:14,290
When the sun was not quite
as bright as it was now,
309
00:18:14,290 --> 00:18:15,860
Venus was much more habitable.
310
00:18:16,850 --> 00:18:20,100
But just a little bit of
increase in solar brightness
311
00:18:20,100 --> 00:18:23,200
kicked off a runaway greenhouse effect
312
00:18:23,200 --> 00:18:25,280
where the oceans evaporated,
313
00:18:25,280 --> 00:18:27,130
put water vapor into the atmosphere
314
00:18:27,130 --> 00:18:29,070
that increased the greenhouse,
315
00:18:29,070 --> 00:18:32,780
and it ran away to become
the very hot, very dry planet
316
00:18:32,780 --> 00:18:33,640
we see today.
317
00:18:34,980 --> 00:18:38,790
- We definitely believe that
Venus had much more water
318
00:18:38,790 --> 00:18:41,410
at the surface than it does today.
319
00:18:41,410 --> 00:18:44,470
Potentially, a shallow
ocean's worth of water.
320
00:18:44,470 --> 00:18:45,970
We really have no information
321
00:18:45,970 --> 00:18:48,290
about when that water was lost.
322
00:18:49,280 --> 00:18:51,240
- That water could have persisted
323
00:18:51,240 --> 00:18:55,030
for billions of years, billions.
324
00:18:55,030 --> 00:18:59,730
And, on Earth, life evolved
incredibly quickly, actually,
325
00:18:59,730 --> 00:19:04,010
considering the meteorites
that were hitting the Earth.
326
00:19:04,010 --> 00:19:05,910
So why not Venus?
327
00:19:05,910 --> 00:19:08,060
And if the answer is, "It
didn't happen on Venus,"
328
00:19:08,060 --> 00:19:09,510
that tells us something, too.
329
00:19:12,295 --> 00:19:13,605
(eruptions rumbling)
330
00:19:13,610 --> 00:19:16,200
- [Narrator] As Venus lost its water,
331
00:19:16,200 --> 00:19:17,710
its atmosphere gave way
332
00:19:17,710 --> 00:19:20,460
to the noxious outpourings of volcanoes,
333
00:19:21,600 --> 00:19:24,230
the primary source of carbon dioxide.
334
00:19:24,232 --> 00:19:27,262
(soft music)
335
00:19:27,260 --> 00:19:30,470
But Venus lost its ability
to recapture that carbon,
336
00:19:31,970 --> 00:19:34,840
trapping itself in a terrifying loop.
337
00:19:36,770 --> 00:19:38,300
- Ultimately, the oceans boiled off
338
00:19:38,300 --> 00:19:40,860
partly because of the greenhouse property
339
00:19:40,860 --> 00:19:42,420
of water vapor itself,
340
00:19:42,420 --> 00:19:44,100
leading to this positive feedback
341
00:19:44,100 --> 00:19:46,620
where the more water that evaporates,
342
00:19:46,620 --> 00:19:47,760
the more the planet heats up
343
00:19:47,760 --> 00:19:50,340
because of the greenhouse
effect of the water vapor.
344
00:19:50,340 --> 00:19:52,330
And then, once the oceans boil off
345
00:19:52,330 --> 00:19:54,230
and Venus loses its oceans,
346
00:19:54,230 --> 00:19:57,180
then that destroys the carbon cycle
347
00:19:57,180 --> 00:20:01,960
because you still have CO2
coming out of volcanoes on Venus,
348
00:20:01,960 --> 00:20:04,100
but there's no way to remove that CO2.
349
00:20:04,100 --> 00:20:07,510
The sink disappeared when
the water disappeared
350
00:20:07,510 --> 00:20:11,470
and then the thermostat sorta
gets pegged in the red zone
351
00:20:11,470 --> 00:20:13,370
because you're just
adding more and more CO2
352
00:20:13,370 --> 00:20:15,060
to the atmosphere from volcanoes.
353
00:20:15,060 --> 00:20:16,830
And it can't lose it anymore
354
00:20:16,830 --> 00:20:18,740
without that mediating effect of water,
355
00:20:18,740 --> 00:20:21,600
and it ends up in that
runaway greenhouse state.
356
00:20:21,595 --> 00:20:24,885
(eruptions rumbling)
357
00:20:24,891 --> 00:20:28,351
(dramatic music)
358
00:20:28,350 --> 00:20:31,370
- [Narrator] Why did
volcanic CO2 runaway on Venus
359
00:20:33,710 --> 00:20:36,000
while Earth kept it at trace levels?
360
00:20:39,400 --> 00:20:41,510
One reason is a basic difference
361
00:20:41,510 --> 00:20:43,680
in the geology of the two planets.
362
00:20:44,670 --> 00:20:48,650
Earth, like Venus, harbors
a core of molten iron.
363
00:20:50,240 --> 00:20:54,400
Over time, the radioactive
decay of uranium, thorium,
364
00:20:54,400 --> 00:20:56,490
and potassium generates heat.
365
00:20:59,720 --> 00:21:02,030
Hot liquid rock punches through
366
00:21:02,030 --> 00:21:06,030
where Earth's crust is thinnest,
in the middle of oceans,
367
00:21:06,030 --> 00:21:08,370
and floods the seafloor with lava.
368
00:21:10,060 --> 00:21:12,590
In a process called plate tectonics,
369
00:21:13,460 --> 00:21:16,000
growing undersea mountains push aside
370
00:21:16,000 --> 00:21:19,320
raft-like sections of
the crust, the plates.
371
00:21:19,323 --> 00:21:22,533
(plates rumbling)
372
00:21:22,530 --> 00:21:25,720
When they collide with
thicker continental crust,
373
00:21:25,720 --> 00:21:27,410
they can dive beneath them.
374
00:21:29,940 --> 00:21:34,940
As they do, grinding friction
causes rocks to melt,
375
00:21:34,950 --> 00:21:39,950
hasten by oceanic water,
forming reservoirs of magma.
376
00:21:42,710 --> 00:21:45,030
The pressure increases,
377
00:21:45,030 --> 00:21:48,260
until finally, a volcano erupts.
378
00:21:48,259 --> 00:21:53,259
(intense music)
(eruption booming)
379
00:21:53,350 --> 00:21:54,900
Plate tectonics generates
380
00:21:54,900 --> 00:21:57,790
up to 80 volcanic eruptions each year.
381
00:21:59,430 --> 00:22:02,470
Sometimes, this process can release energy
382
00:22:02,470 --> 00:22:04,720
on such a large scale
383
00:22:04,720 --> 00:22:07,780
that it changes the
course of Earth's history.
384
00:22:07,778 --> 00:22:10,448
(lava sizzling)
385
00:22:15,280 --> 00:22:19,080
Today, Yellowstone National
Park in North America
386
00:22:19,080 --> 00:22:22,750
is an open laboratory of
Earth's remarkable geology.
387
00:22:22,754 --> 00:22:25,594
(geyser rumbling)
388
00:22:26,770 --> 00:22:30,720
The rich mix of organic
chemicals and geothermal energy
389
00:22:30,720 --> 00:22:33,510
in places like this may have given rise
390
00:22:33,510 --> 00:22:36,440
to living organisms billions of years ago.
391
00:22:38,950 --> 00:22:42,270
The hot springs and geysers
we come here to admire
392
00:22:42,270 --> 00:22:44,900
are fueled by a dome of magma
393
00:22:44,900 --> 00:22:47,260
that is building deep below ground.
394
00:22:47,256 --> 00:22:50,416
(soft dramatic music)
395
00:22:51,870 --> 00:22:55,640
At intervals of roughly
every 600,000 years,
396
00:22:55,640 --> 00:22:59,540
this dome pushes the land
up into a broad plateau.
397
00:23:01,230 --> 00:23:04,630
Inevitably, hot gas and lave explode
398
00:23:04,630 --> 00:23:06,180
through the cracks in the land.
399
00:23:07,490 --> 00:23:10,490
The plateau suddenly
and violently collapses,
400
00:23:10,490 --> 00:23:12,740
triggering eruptions so large,
401
00:23:12,740 --> 00:23:15,240
they'd blanket the continent with ash.
402
00:23:15,236 --> 00:23:20,236
(eruptions booming)
(intense music)
403
00:23:23,550 --> 00:23:27,230
- Plate tectonics is really
what makes Earth tick.
404
00:23:27,230 --> 00:23:31,300
Plate tectonics is the sort of
overall organizing principle,
405
00:23:31,300 --> 00:23:32,520
almost, of Earth's behavior.
406
00:23:32,520 --> 00:23:34,520
Not just the obvious continental drift
407
00:23:34,520 --> 00:23:35,920
and the movement of the continents,
408
00:23:35,920 --> 00:23:38,260
but even the carbon cycle
and the climate cycle
409
00:23:38,260 --> 00:23:40,060
and all of these other aspects of Earth
410
00:23:40,060 --> 00:23:41,920
that have to do with the way things cycle
411
00:23:41,920 --> 00:23:44,360
between the interior and the surface
412
00:23:44,360 --> 00:23:45,730
come down to plate tectonics.
413
00:23:45,730 --> 00:23:47,940
And Venus doesn't have plate tectonics.
414
00:23:47,937 --> 00:23:50,577
(slow music)
415
00:23:50,580 --> 00:23:51,650
- [Narrator] You can see why
416
00:23:51,650 --> 00:23:54,420
by cutting into the crust
of these sister planets.
417
00:23:56,320 --> 00:23:58,510
Earth has only about eight kilometers
418
00:23:58,510 --> 00:24:00,430
of hard crust under the oceans
419
00:24:00,430 --> 00:24:02,930
and no more than 30 kilometers under land.
420
00:24:04,170 --> 00:24:07,560
But the skin of Venus
is about twice as thick,
421
00:24:07,560 --> 00:24:12,080
acting as a rigid lid,
locking the surface in place.
422
00:24:13,720 --> 00:24:15,490
- If Earth did not have volatile cycling
423
00:24:15,490 --> 00:24:17,020
throughout most of its history,
424
00:24:17,020 --> 00:24:19,460
and we had a stagnant plate mode,
425
00:24:19,460 --> 00:24:21,350
like we have on Venus today,
426
00:24:21,350 --> 00:24:23,650
then all of the nitrogen
and all the carbon dioxide
427
00:24:23,650 --> 00:24:25,080
that we see in Venus's atmosphere
428
00:24:25,080 --> 00:24:27,000
would be in our atmosphere
in the same way.
429
00:24:26,999 --> 00:24:30,289
(soft dramatic music)
430
00:24:30,290 --> 00:24:31,840
- [Narrator] The dense shell of Venus
431
00:24:31,840 --> 00:24:34,470
may never have separated
into continental plates,
432
00:24:35,520 --> 00:24:37,890
but the heat must still find a way out.
433
00:24:37,887 --> 00:24:40,797
(foreboding music)
434
00:25:09,900 --> 00:25:13,290
- Venus is a really volcanic planet.
435
00:25:14,250 --> 00:25:17,300
Most of the surface of
Venus is actually covered
436
00:25:17,300 --> 00:25:22,010
by volcanoes and several
different types of volcanoes.
437
00:25:23,900 --> 00:25:26,940
- From the smallest
things that we can measure
438
00:25:26,940 --> 00:25:28,370
in the radar data,
439
00:25:28,370 --> 00:25:31,200
which is about a hundred meters per pixel,
440
00:25:31,200 --> 00:25:34,570
to huge lava flows,
441
00:25:34,570 --> 00:25:39,180
just lava flows that stretch
for thousands of kilometers.
442
00:25:39,177 --> 00:25:41,587
(slow music)
443
00:25:46,793 --> 00:25:49,543
(mystical music)
444
00:25:51,800 --> 00:25:53,090
- [Narrator] The Magellan Mission
445
00:25:53,090 --> 00:25:55,320
documented a zoo of volcano types.
446
00:26:00,240 --> 00:26:02,920
- Venus has some shield volcanoes.
447
00:26:02,920 --> 00:26:05,370
Shield volcanoes have low slopes,
448
00:26:05,371 --> 00:26:10,131
and they look like warrior
shields laid on the ground.
449
00:26:10,130 --> 00:26:11,690
That's where the name came from.
450
00:26:11,690 --> 00:26:13,530
In fact, it came from Iceland.
451
00:26:15,300 --> 00:26:20,180
Venus also has several
other types of volcanoes
452
00:26:20,180 --> 00:26:24,700
that we don't see in other
places in the solar system.
453
00:26:24,700 --> 00:26:27,910
For example, one very unusual type
454
00:26:27,910 --> 00:26:31,730
are some domes that we call pancake domes,
455
00:26:31,730 --> 00:26:35,350
and that's because they
really look like pancakes.
456
00:26:35,350 --> 00:26:36,960
They are flat on top.
457
00:26:36,960 --> 00:26:38,930
They have steep sides.
458
00:26:43,800 --> 00:26:47,970
Some of these domes have some
fractured and jagged edges,
459
00:26:48,810 --> 00:26:50,880
and they are known as ticks
460
00:26:50,880 --> 00:26:53,750
because they look like squashed bugs.
461
00:26:55,870 --> 00:26:59,250
Arachnoids because they
have a fracture pattern
462
00:26:59,250 --> 00:27:01,610
similar to a spider's web,
463
00:27:01,610 --> 00:27:05,850
with some concentric fractures
and some radial fractures.
464
00:27:10,550 --> 00:27:14,200
- [Narrator] The enormous
volcanic features called coronae
465
00:27:14,200 --> 00:27:16,750
hint that Venus may be subducting rocks
466
00:27:16,750 --> 00:27:18,970
back into its interior, after all.
467
00:27:20,400 --> 00:27:23,790
- [Rosaly] Corona on
Venus are in a way similar
468
00:27:23,790 --> 00:27:25,240
to calderas on Earth,
469
00:27:25,240 --> 00:27:28,630
where you have a pattern
of concentric fractures.
470
00:27:28,630 --> 00:27:31,560
There is a collapse or
successive collapses.
471
00:27:33,810 --> 00:27:35,790
- A plume of hot stuff comes up,
472
00:27:35,790 --> 00:27:38,260
pushes up the surface, breaks the surface,
473
00:27:38,260 --> 00:27:40,470
and a bunch of vulcanism
forms at the surface,
474
00:27:40,470 --> 00:27:42,260
much like what we see at Hawaii.
475
00:27:44,980 --> 00:27:47,240
- [Narrator] The two volcanoes
that built the Big Island
476
00:27:47,240 --> 00:27:50,980
are, together, about
150 kilometers across.
477
00:27:52,690 --> 00:27:57,050
But a few of the coronae on
Venus have grown much larger.
478
00:27:58,430 --> 00:28:00,940
- [Sue] There are a couple
of very big features.
479
00:28:00,940 --> 00:28:04,060
One is 2,600 kilometers across.
480
00:28:06,830 --> 00:28:08,980
- On Venus, where we don't see
481
00:28:08,980 --> 00:28:10,820
evidence of plate tectonics,
482
00:28:10,820 --> 00:28:12,810
volcanoes are really the primary way
483
00:28:12,810 --> 00:28:14,950
that we believe Venus is
trying to lose its heat
484
00:28:14,950 --> 00:28:16,260
or has lost its heat.
485
00:28:16,260 --> 00:28:19,710
And so that record that we see
of volcanism on the surface
486
00:28:19,710 --> 00:28:23,580
is essentially telling us how
Venus is trying to cool off,
487
00:28:23,580 --> 00:28:25,540
how its interior is losing heat
488
00:28:25,540 --> 00:28:28,970
and moving that hot magma and
hot lava onto the surface.
489
00:28:28,969 --> 00:28:30,969
(eruption rumbling)
(sinister music)
490
00:28:30,970 --> 00:28:33,190
- [Tony] About 500 million years
491
00:28:33,190 --> 00:28:36,090
to a billion years or so ago,
492
00:28:36,090 --> 00:28:38,780
something catastrophic happened.
493
00:28:38,780 --> 00:28:42,680
When you look at Venus's
surface from satellites
494
00:28:42,680 --> 00:28:46,000
and you count the craters
that you see on the surface,
495
00:28:46,000 --> 00:28:49,100
we find out that the vast
majority of Venus's surface
496
00:28:49,100 --> 00:28:51,580
is geologically very young.
497
00:28:51,581 --> 00:28:53,181
(lava sloshing)
498
00:28:53,180 --> 00:28:54,720
- Half a billion years ago,
499
00:28:54,720 --> 00:28:59,720
Venus had cause to erupt
volcanoes over its entire surface,
500
00:29:00,630 --> 00:29:03,040
its entire Earth-sized surface.
501
00:29:03,040 --> 00:29:05,390
And we're still trying to figure out
502
00:29:05,390 --> 00:29:07,060
how that happened and why.
503
00:29:07,055 --> 00:29:12,055
(lava sloshing)
(mysterious music)
504
00:29:12,460 --> 00:29:15,310
- [Narrator] With its steadily
declining stores of water,
505
00:29:16,200 --> 00:29:17,650
lack of magnetic field,
506
00:29:19,090 --> 00:29:22,660
no plate tectonics to drag
carbon down into its crust,
507
00:29:23,750 --> 00:29:27,370
but hordes of volcanoes
blasting CO2 into its skies,
508
00:29:28,680 --> 00:29:32,020
Venus sentenced its
surface to climatic death.
509
00:29:34,300 --> 00:29:36,630
A planet turned inside out.
510
00:29:36,631 --> 00:29:39,381
(dramatic music)
511
00:29:46,682 --> 00:29:49,862
(light music)
512
00:29:49,860 --> 00:29:53,810
Meanwhile, its sister planet,
Earth, managed to survive,
513
00:29:53,810 --> 00:29:56,800
to nurture a complex
and evolving biosphere.
514
00:29:59,740 --> 00:30:02,400
The contrasting stories of Earth and Venus
515
00:30:02,400 --> 00:30:05,820
are central to one of the
greatest quests in science today.
516
00:30:07,200 --> 00:30:09,320
The search for solar systems
517
00:30:09,320 --> 00:30:12,380
and life-bearing worlds out in the galaxy.
518
00:30:17,630 --> 00:30:20,150
That search, conducted by a growing array
519
00:30:20,150 --> 00:30:23,100
of ground and space-based observatories,
520
00:30:23,100 --> 00:30:25,960
has so far turned up over 4,000 planets
521
00:30:25,960 --> 00:30:28,970
with thousands more detected,
but not yet confirmed.
522
00:30:28,965 --> 00:30:32,225
(mystical music)
523
00:30:32,230 --> 00:30:34,710
Increasing numbers of these exoplanets
524
00:30:34,710 --> 00:30:36,850
are close in size to Earth and Venus.
525
00:30:38,580 --> 00:30:40,420
With orbits within the habitable zones
526
00:30:40,420 --> 00:30:42,430
of their solar systems,
527
00:30:42,430 --> 00:30:45,460
where water can exist in all three states,
528
00:30:45,460 --> 00:30:47,220
liquid, ice, and steam,
529
00:30:48,610 --> 00:30:52,500
statistical studies indicate
there could be billions of them
530
00:30:52,500 --> 00:30:54,950
tucked into the nooks and
crannies of our galaxy.
531
00:30:59,706 --> 00:31:01,566
(gentle music)
532
00:31:01,570 --> 00:31:04,700
Is life, even intelligent life,
533
00:31:05,870 --> 00:31:08,330
a natural product of the laws of nature?
534
00:31:11,960 --> 00:31:13,490
Or is it a fluke?
535
00:31:14,680 --> 00:31:16,900
Its chances mostly killed off
536
00:31:16,900 --> 00:31:20,050
by all that can go wrong
with planetary evolution.
537
00:31:24,570 --> 00:31:28,000
So far, Venus has not told us
538
00:31:28,000 --> 00:31:29,650
all it can about these questions.
539
00:31:32,740 --> 00:31:34,140
- For years and years,
540
00:31:34,140 --> 00:31:37,820
after we began to really understand Venus,
541
00:31:37,820 --> 00:31:40,280
all of the scientists
and the space advocates
542
00:31:40,280 --> 00:31:42,390
were saying, "Oh, no,
Venus is the one place
543
00:31:42,387 --> 00:31:47,387
"we don't want to go to because
it's so hot on the surface.
544
00:31:47,797 --> 00:31:50,227
"It's hot enough to melt land."
545
00:31:50,230 --> 00:31:52,750
But it turns out that, like Earth,
546
00:31:52,750 --> 00:31:55,400
as you get higher in the atmosphere,
547
00:31:55,400 --> 00:31:57,170
the temperature gets cooler.
548
00:31:57,170 --> 00:31:59,020
And there's a region where Venus
549
00:31:59,020 --> 00:32:01,040
is very, very much like the conditions
550
00:32:01,040 --> 00:32:01,950
at the sea level on Earth.
551
00:32:01,945 --> 00:32:04,265
(wind whooshing)
(gentle music)
552
00:32:04,270 --> 00:32:06,240
- [Narrator] The presence
of hospitable conditions
553
00:32:06,240 --> 00:32:08,000
in Venus's upper atmosphere
554
00:32:08,940 --> 00:32:11,460
led to one of the most
innovative mission ideas
555
00:32:11,460 --> 00:32:12,420
on the books.
556
00:32:14,060 --> 00:32:16,190
Imagine an entry vehicle penetrating
557
00:32:16,190 --> 00:32:18,770
the outer most layers
of Venus's atmosphere.
558
00:32:20,140 --> 00:32:22,020
Instead of continuing to the surface,
559
00:32:23,340 --> 00:32:25,250
it deploys an inflating envelope.
560
00:32:25,253 --> 00:32:28,773
(balloon flapping)
561
00:32:28,770 --> 00:32:32,360
An airship up to 130 meters in length.
562
00:32:33,732 --> 00:32:36,032
(soft dramatic music)
563
00:32:36,030 --> 00:32:37,410
This platform,
564
00:32:37,410 --> 00:32:41,890
called the High-Altitude Venus
Operational Concept, HAVOC,
565
00:32:41,890 --> 00:32:44,560
would host a series of
experiments and sensors.
566
00:32:44,558 --> 00:32:48,348
(low intense music)
567
00:32:48,350 --> 00:32:49,950
And its most far-ranging.
568
00:32:51,200 --> 00:32:53,730
It's the start of a
permanent human outpost.
569
00:32:58,230 --> 00:33:01,620
A science city built
in the clouds of Venus.
570
00:33:03,725 --> 00:33:06,225
(light music)
571
00:33:07,710 --> 00:33:09,130
The concept takes advantage
572
00:33:09,130 --> 00:33:11,720
of the unique profile
of Venus's atmosphere.
573
00:33:13,690 --> 00:33:17,300
At ground level, the pressure
is like being 900 meters deep
574
00:33:17,300 --> 00:33:18,890
in Earth's oceans.
575
00:33:18,890 --> 00:33:21,620
It's hotter than anywhere
else in the solar system,
576
00:33:21,620 --> 00:33:22,800
except the sun.
577
00:33:24,130 --> 00:33:27,660
But 50 kilometers up, among the clouds,
578
00:33:27,660 --> 00:33:31,090
the pressure has dropped to
that of sea level on Earth.
579
00:33:31,090 --> 00:33:34,540
It's no warmer than a day in
June in Europe or the U.S.
580
00:33:35,682 --> 00:33:37,462
(propellers clicking)
581
00:33:37,460 --> 00:33:40,970
That's where balloon-born
habitats could perpetually float.
582
00:33:40,973 --> 00:33:43,563
(gentle music)
583
00:33:48,570 --> 00:33:52,960
Consider a crew of scientist
astronauts aboard an airship.
584
00:33:52,962 --> 00:33:54,572
(thunder rumbling)
585
00:33:54,570 --> 00:33:57,590
Making their way through
the sulfuric acid clouds,
586
00:33:58,980 --> 00:34:01,820
their ships' electric
motors powered by the sun,
587
00:34:03,600 --> 00:34:06,610
on their way home from a survey mission.
588
00:34:13,450 --> 00:34:15,710
- [Geoff] The nice
thing about the balloons
589
00:34:15,710 --> 00:34:19,190
in the atmosphere of Venus,
if they're very, very large,
590
00:34:19,190 --> 00:34:21,790
is that they'd be riding
with the inside pressure
591
00:34:21,790 --> 00:34:24,050
about the same as the outside pressure.
592
00:34:25,140 --> 00:34:28,360
It wouldn't burst like a balloon
in a catastrophic failure.
593
00:34:30,100 --> 00:34:32,760
- [Narrator] These sequences
show a well-developed version
594
00:34:32,760 --> 00:34:34,390
of a Venus cloud city.
595
00:34:36,080 --> 00:34:39,230
The construction of stations
this large and complex
596
00:34:39,230 --> 00:34:42,040
depends on our ability
to harvest materials,
597
00:34:42,040 --> 00:34:45,090
like carbon fiber, directly
from the atmosphere.
598
00:34:46,645 --> 00:34:49,805
(propellers clicking)
599
00:34:51,430 --> 00:34:54,640
Its core mission to
serve as a field station
600
00:34:54,640 --> 00:34:57,140
for deploying research
probes around the planet
601
00:34:58,820 --> 00:35:00,720
and down to its hostile terrain.
602
00:35:06,050 --> 00:35:08,190
From their floating platforms,
603
00:35:08,190 --> 00:35:10,330
these experimenters would investigate
604
00:35:10,330 --> 00:35:13,400
the deep history of Venus's surface
605
00:35:13,400 --> 00:35:15,960
and how land and atmosphere connect.
606
00:35:17,260 --> 00:35:18,620
(lava sloshing)
607
00:35:18,620 --> 00:35:21,310
They would check for
signatures of live volcanoes
608
00:35:22,456 --> 00:35:25,976
and the interaction of the
atmosphere's physical, chemical,
609
00:35:25,980 --> 00:35:28,860
and possibly biological components.
610
00:35:28,864 --> 00:35:32,864
(lava sloshing)
(light music)
611
00:35:32,864 --> 00:35:34,324
(air whooshing)
612
00:35:34,320 --> 00:35:36,340
All in a quest to discover
613
00:35:36,340 --> 00:35:39,510
what went so terribly wrong on Venus.
614
00:35:41,352 --> 00:35:44,592
(soft dramatic music)
615
00:35:44,590 --> 00:35:47,700
Soviet researchers first
demonstrated balloon science
616
00:35:47,700 --> 00:35:50,750
with the 1985 Vega 2 probe,
617
00:35:50,750 --> 00:35:53,400
riding turbulent
hurricane-force thermal currents
618
00:35:53,400 --> 00:35:55,390
at 240 kilometers per hour.
619
00:35:59,960 --> 00:36:03,040
Vega 2's three and a half
meter diameter balloon
620
00:36:03,040 --> 00:36:06,630
found a stable altitude
at about 54 kilometers.
621
00:36:06,634 --> 00:36:07,704
(lightning clapping)
622
00:36:07,700 --> 00:36:11,340
In the most active of the
planet's three cloud layers,
623
00:36:11,340 --> 00:36:14,150
it traveled more than 7,400 kilometers
624
00:36:14,150 --> 00:36:16,260
around to the day side of Venus.
625
00:36:16,261 --> 00:36:18,501
(thunder rumbling)
626
00:36:18,501 --> 00:36:23,501
(propellers clicking)
(gentle music)
627
00:36:25,830 --> 00:36:29,020
Vega 2's descendants
may deploy from airships
628
00:36:29,020 --> 00:36:30,900
to sample specific altitudes.
629
00:36:37,346 --> 00:36:39,106
Triangulating their positions,
630
00:36:39,110 --> 00:36:41,960
they could form a global sensor network
631
00:36:41,960 --> 00:36:44,260
to pick up signs of seismic activity.
632
00:36:46,503 --> 00:36:50,053
(ground rumbling)
633
00:36:50,050 --> 00:36:53,490
- So our balloon can
listen for earthquakes
634
00:36:53,490 --> 00:36:55,660
as it floats around Venus,
635
00:36:55,660 --> 00:36:57,030
taking advantage of the fact
636
00:36:57,030 --> 00:36:59,610
that the Venus atmosphere is so thick
637
00:36:59,610 --> 00:37:02,580
that sound waves from
earthquakes will propagate up
638
00:37:02,580 --> 00:37:03,410
through the atmosphere
639
00:37:03,413 --> 00:37:06,983
and can be measured from
balloon or from orbit.
640
00:37:06,980 --> 00:37:07,910
It's astounding.
641
00:37:08,848 --> 00:37:11,678
(ground rumbling)
642
00:37:12,863 --> 00:37:15,613
(dramatic music)
643
00:37:16,500 --> 00:37:17,330
- [Narrator] Though it may appear
644
00:37:17,333 --> 00:37:20,073
as a featureless planet-wide cloud bank,
645
00:37:20,070 --> 00:37:23,710
Venus's atmosphere has its
own complex stories to tell.
646
00:37:25,360 --> 00:37:26,960
- One of the most important things
647
00:37:26,960 --> 00:37:29,080
in the atmosphere of Venus that we need
648
00:37:29,080 --> 00:37:32,980
is to understand some
of the molecular fossils
649
00:37:32,980 --> 00:37:35,260
that are left in Venus's atmosphere.
650
00:37:35,260 --> 00:37:40,260
The noble gases of argon,
neon, xenon, krypton,
651
00:37:40,370 --> 00:37:43,910
those gases that don't
react with anything else.
652
00:37:43,910 --> 00:37:46,090
They've been in the
atmosphere since Venus formed,
653
00:37:46,090 --> 00:37:47,660
since the atmosphere formed.
654
00:37:47,660 --> 00:37:48,920
And if we can measure those,
655
00:37:48,920 --> 00:37:51,120
they provide us these fossil evidence
656
00:37:51,120 --> 00:37:54,100
of what that original
atmosphere on Venus looked like.
657
00:37:54,097 --> 00:37:56,827
(gases hissing)
658
00:37:56,830 --> 00:37:59,140
- [Narrator] A profile
of the early atmosphere
659
00:37:59,140 --> 00:38:02,320
would tell us whether Venus
once held lakes and rivers
660
00:38:02,320 --> 00:38:03,380
on its surface.
661
00:38:08,766 --> 00:38:13,766
(propellers ticking)
(intense music)
662
00:38:14,030 --> 00:38:17,940
If humans do someday visit
the acidic clouds of Venus,
663
00:38:17,940 --> 00:38:22,610
they may find, strictly
speaking, that they're not alone.
664
00:38:23,580 --> 00:38:25,490
For more than 100 years,
665
00:38:25,490 --> 00:38:29,310
astronomers on Earth have
noticed enigmatic dark patches
666
00:38:29,310 --> 00:38:31,930
that appear only at
ultraviolet wavelengths.
667
00:38:33,420 --> 00:38:36,330
- My Venus atmosphere friends talk about
668
00:38:36,330 --> 00:38:39,600
the fact that there is a
signature in the atmosphere
669
00:38:39,600 --> 00:38:40,900
that they can't explain.
670
00:38:41,750 --> 00:38:43,640
And there is something in the clouds
671
00:38:43,640 --> 00:38:48,100
that absorbs UV radiation and
they don't know what it is.
672
00:38:48,100 --> 00:38:53,100
That signature may be due
to absorption by biota,
673
00:38:54,130 --> 00:38:56,360
by cloud creatures.
674
00:38:58,200 --> 00:39:01,310
- There are nutrients. There's liquid.
675
00:39:01,310 --> 00:39:02,820
There are a lot of the elements
676
00:39:02,820 --> 00:39:06,200
that we think of being
requirements for life.
677
00:39:06,200 --> 00:39:08,460
The one impediment to life
678
00:39:08,460 --> 00:39:10,800
may be the strong acid in the clouds,
679
00:39:10,800 --> 00:39:12,490
but we've learned more recently
680
00:39:12,490 --> 00:39:15,000
of all these extremophile
organisms on Earth,
681
00:39:15,000 --> 00:39:17,730
including what we call
acidophilic organisms
682
00:39:17,730 --> 00:39:20,150
or organisms that love
living in strong acid.
683
00:39:20,145 --> 00:39:22,835
(dramatic music)
684
00:39:22,840 --> 00:39:24,220
- There are bacteria on Earth,
685
00:39:24,219 --> 00:39:27,709
Thiobacillus ferroxidans, for example,
686
00:39:27,710 --> 00:39:29,040
which have an absorption spectrum
687
00:39:29,040 --> 00:39:31,790
which is very similar
to what we see on Venus.
688
00:39:33,890 --> 00:39:36,510
- [Narrator] Could life have
developed and migrated upward
689
00:39:36,510 --> 00:39:38,050
as the surface became lethal?
690
00:39:39,690 --> 00:39:40,720
In Earth's atmosphere,
691
00:39:40,720 --> 00:39:43,940
microbes have been found at
altitudes up to 40 kilometers.
692
00:39:43,941 --> 00:39:48,091
(air whooshing)
(light music)
693
00:39:48,090 --> 00:39:49,390
- [Mike] Earth has had 4 billion years
694
00:39:49,390 --> 00:39:52,520
for life to fill every
ecological niche possible.
695
00:39:52,520 --> 00:39:54,420
And we find life everywhere we go.
696
00:39:54,420 --> 00:39:56,580
We dig deep wells, we
find life down there.
697
00:39:56,580 --> 00:39:58,020
We find life in the clouds.
698
00:40:00,420 --> 00:40:02,760
- If we have the
opportunity to go to Venus
699
00:40:02,760 --> 00:40:04,830
and float in the Venus clouds,
700
00:40:04,830 --> 00:40:06,990
we should at least think about
701
00:40:06,990 --> 00:40:09,350
if we can measure the conditions
702
00:40:09,350 --> 00:40:12,430
that might be reasonable for life today
703
00:40:12,430 --> 00:40:15,860
and also any signature of life
in the clouds of Venus today.
704
00:40:15,859 --> 00:40:19,029
(soft dramatic music)
705
00:40:22,669 --> 00:40:25,369
(intense music)
706
00:40:25,370 --> 00:40:28,240
- [Narrator] Though the
cloud tops may be temperate,
707
00:40:28,240 --> 00:40:30,740
the hot surface is merciless.
708
00:40:32,420 --> 00:40:35,800
Venus engineers must take
a mechanical approach
709
00:40:35,800 --> 00:40:38,160
because even the most robust electronics
710
00:40:38,160 --> 00:40:39,820
developed for the military
711
00:40:39,820 --> 00:40:43,320
stop working at about 125 degrees Celsius.
712
00:40:45,430 --> 00:40:46,770
- Let me show you something.
713
00:40:46,770 --> 00:40:47,730
So this it's a clock
714
00:40:47,730 --> 00:40:49,660
that is fully made out of stainless steel.
715
00:40:49,660 --> 00:40:53,160
It's been baked out at 460 degrees Celsius
716
00:40:53,160 --> 00:40:55,610
and has been operated in an oven.
717
00:40:55,610 --> 00:40:58,460
And our goal with this was
to start to understand,
718
00:40:58,460 --> 00:41:01,180
what are the challenges
when you build mechanisms
719
00:41:01,180 --> 00:41:03,580
to operate in Venus conditions?
720
00:41:03,580 --> 00:41:06,010
First of all, the spring
material was really important.
721
00:41:06,010 --> 00:41:07,760
We have a clock spring here,
722
00:41:07,760 --> 00:41:09,600
as well as also a balance
spring right here,
723
00:41:09,600 --> 00:41:11,560
that is built out of Inconel.
724
00:41:11,560 --> 00:41:13,610
Even when you're going
to extreme temperatures,
725
00:41:13,610 --> 00:41:16,460
like Venus, 462 degrees Celsius,
726
00:41:16,460 --> 00:41:19,170
the entire assembly would just
expand and contract together
727
00:41:19,170 --> 00:41:20,700
and you wouldn't get jamming.
728
00:41:20,700 --> 00:41:22,630
And we were able to
demonstrate and show that
729
00:41:22,630 --> 00:41:23,750
by operating this clock.
730
00:41:23,745 --> 00:41:26,865
(clock clicking)
731
00:41:26,870 --> 00:41:29,620
(dramatic music)
732
00:41:32,065 --> 00:41:34,015
- [Narrator] As on Mars,
733
00:41:34,020 --> 00:41:37,360
exploring the surface of
Venus will require mobility.
734
00:41:39,980 --> 00:41:42,030
But strategies that work for other worlds
735
00:41:43,050 --> 00:41:44,520
don't work on Venus.
736
00:41:46,490 --> 00:41:48,100
Not even solar power.
737
00:41:50,140 --> 00:41:53,030
- Venus does have some
solar power on the surface.
738
00:41:53,030 --> 00:41:57,020
Although, it's a fraction of
what is available here on Earth
739
00:41:57,020 --> 00:41:59,280
is actually available
on the surface of Venus
740
00:41:59,280 --> 00:42:01,200
due to the thick cloud layers,
741
00:42:01,200 --> 00:42:03,000
due to also the red shifting of the light,
742
00:42:03,000 --> 00:42:05,800
and that solar panels
don't work as efficiently.
743
00:42:05,800 --> 00:42:08,190
The other big challenge
with using solar on Venus
744
00:42:08,190 --> 00:42:12,780
is that Venus has a very
long night, about 60 days.
745
00:42:12,780 --> 00:42:15,710
Therefore, one of the places
we're looking to get energy
746
00:42:15,710 --> 00:42:16,540
is from the wind.
747
00:42:16,543 --> 00:42:19,333
The idea is you have
low-speed, high-density wind
748
00:42:19,330 --> 00:42:21,760
coming at you, collect
that with a wind turbine,
749
00:42:21,760 --> 00:42:23,850
and then directly transfer
that to the wheels
750
00:42:23,850 --> 00:42:28,000
to drive you at low speed, high torque.
751
00:42:28,000 --> 00:42:30,850
You want to directly use that wind energy
752
00:42:30,850 --> 00:42:34,220
to move yourself mechanically
around the surface of Venus.
753
00:42:35,120 --> 00:42:38,010
- We have the sensors on the surface.
754
00:42:38,010 --> 00:42:39,840
We have the radio on the surface.
755
00:42:39,840 --> 00:42:43,630
But most of the processing
power, most of the computers,
756
00:42:43,630 --> 00:42:45,880
most of the things that run the mission
757
00:42:45,880 --> 00:42:47,750
would be high overhead.
758
00:42:47,750 --> 00:42:50,100
We could either put them
perhaps in an airplane
759
00:42:50,100 --> 00:42:53,980
flying 50 kilometers above,
or maybe in a satellite.
760
00:42:53,982 --> 00:42:56,262
(propellers clicking)
761
00:42:56,260 --> 00:42:58,570
The winds of Venus are pretty ferocious.
762
00:42:58,570 --> 00:43:02,280
The winds of Venus are
going 100 meters per second.
763
00:43:02,280 --> 00:43:04,970
Well, one thing we could
do is just fly around
764
00:43:04,970 --> 00:43:07,670
and let the wind take us
where the wind takes us,
765
00:43:07,670 --> 00:43:10,590
as long as we can fly
faster than that wind
766
00:43:10,590 --> 00:43:12,140
so we can stay in the sunlight.
767
00:43:15,111 --> 00:43:18,641
(dramatic music)
(singers vocalizing)
768
00:43:18,640 --> 00:43:21,270
- [Narrator] Venus's extreme surface heat
769
00:43:21,270 --> 00:43:25,050
drives a blustery atmosphere
of toxic acid rain.
770
00:43:25,051 --> 00:43:27,621
(lightning clapping)
(thunder rumbling)
771
00:43:27,620 --> 00:43:29,100
But the planet lies within
772
00:43:29,100 --> 00:43:32,450
what astronomers would think
of as the habitable zone.
773
00:43:34,400 --> 00:43:35,940
- Venus is a really interesting case
774
00:43:35,940 --> 00:43:40,440
because it forces us to think
of where is the inner edge
775
00:43:40,440 --> 00:43:41,820
of the habitable zone.
776
00:43:41,820 --> 00:43:43,780
Presumably now, in our solar system,
777
00:43:43,780 --> 00:43:47,050
it's somewhere between Earth and Venus.
778
00:43:47,050 --> 00:43:49,500
And yet, there was a time earlier
779
00:43:49,500 --> 00:43:51,630
in the life of our solar system
780
00:43:51,630 --> 00:43:54,260
when Venus was within the habitable zone,
781
00:43:54,260 --> 00:43:56,920
when there probably was an ocean on Venus.
782
00:43:56,923 --> 00:43:59,803
(dramatic music)
(singer vocalizing)
783
00:43:59,800 --> 00:44:01,130
- [Lori] Mars, we think at some point,
784
00:44:01,130 --> 00:44:02,690
used to have more atmosphere
785
00:44:02,690 --> 00:44:05,230
and was potentially warmer and wetter.
786
00:44:06,250 --> 00:44:08,660
And Venus probably had less atmosphere,
787
00:44:08,660 --> 00:44:09,850
at some point in the past,
788
00:44:09,850 --> 00:44:13,390
and had significantly more
water than we see today,
789
00:44:13,390 --> 00:44:15,850
which today it seems very, very dry.
790
00:44:15,850 --> 00:44:18,640
And so it's possible, when
Venus did have less atmosphere,
791
00:44:18,640 --> 00:44:21,660
it was habitable when it
had more water available
792
00:44:21,660 --> 00:44:23,100
and less atmosphere.
793
00:44:23,100 --> 00:44:25,440
We very definitely think that
it has changed over time.
794
00:44:25,444 --> 00:44:30,444
(soft dramatic music)
(lava crackling)
795
00:44:31,770 --> 00:44:34,750
- [Narrator] Looking out
in our Milky Way galaxy,
796
00:44:34,750 --> 00:44:37,490
astronomers are seeking
a broader understanding
797
00:44:37,490 --> 00:44:41,290
of how planets form and
what conditions can nurture
798
00:44:41,290 --> 00:44:42,540
an Earth-like world.
799
00:44:44,330 --> 00:44:46,900
All other exoplanets lie too far away
800
00:44:46,900 --> 00:44:48,460
for us to know much about them.
801
00:44:50,040 --> 00:44:52,350
But Venus is giving scientists a chance
802
00:44:52,350 --> 00:44:56,070
to understand the alien planet next door.
803
00:44:59,997 --> 00:45:02,007
(gentle music)
(singer vocalizing)
804
00:45:02,005 --> 00:45:04,755
(water sloshing)
805
00:45:06,780 --> 00:45:10,930
- There's probably millions,
likely billions, of planets
806
00:45:10,930 --> 00:45:13,700
that are like Earth and like Venus.
807
00:45:13,700 --> 00:45:15,260
And we'd like to understand
808
00:45:15,260 --> 00:45:19,160
what made the one turn into a hot desert.
809
00:45:24,740 --> 00:45:26,000
And Earth, on the other hand,
810
00:45:26,000 --> 00:45:29,500
turn into a planet with liquid
water and habitable for life.
811
00:45:29,498 --> 00:45:32,668
(soft dramatic music)
812
00:45:36,090 --> 00:45:38,740
- Different aspects of
Venus's evolutionary history
813
00:45:38,740 --> 00:45:40,970
would put it into the habitable zone.
814
00:45:40,970 --> 00:45:42,900
Then that tells the exoplanet astronomers
815
00:45:42,900 --> 00:45:44,800
that they should not
just discard these worlds
816
00:45:44,800 --> 00:45:46,670
as hot inhospitable planets,
817
00:45:46,670 --> 00:45:49,060
and that they should
go take a look at them.
818
00:45:49,060 --> 00:45:51,550
And that would expand the
idea of the habitable zone
819
00:45:51,550 --> 00:45:53,450
to much closer reaches to the star
820
00:45:53,450 --> 00:45:55,340
than we would otherwise think.
821
00:45:55,338 --> 00:46:00,338
(gentle music)
(water sloshing)
822
00:46:01,650 --> 00:46:03,000
- When we look out in the galaxy
823
00:46:03,000 --> 00:46:04,630
and we see all these Earth-like planets,
824
00:46:04,630 --> 00:46:06,250
we're looking for another Earth, right?
825
00:46:06,250 --> 00:46:11,250
We're looking for another
place that is like our own.
826
00:46:11,750 --> 00:46:14,350
We're looking at Earth-sized planets
827
00:46:14,350 --> 00:46:16,400
and the closest Earth-sized planet
828
00:46:16,400 --> 00:46:18,220
happens to be the closest planet to Earth.
829
00:46:18,223 --> 00:46:21,553
(laughs) It's Venus. It's right there.
830
00:46:21,550 --> 00:46:25,800
So it tells us about how
Earth-sized planets form
831
00:46:25,800 --> 00:46:27,250
and whether or not they're habitable.
832
00:46:27,247 --> 00:46:32,247
(gentle music)
(singer vocalizing)
833
00:46:35,780 --> 00:46:38,950
(soft dramatic music)
834
00:46:40,690 --> 00:46:44,610
- [Narrator] Two planets born together,
835
00:46:46,230 --> 00:46:48,680
nearly the same size and mass.
836
00:46:48,676 --> 00:46:51,486
(lava crackling)
837
00:46:51,490 --> 00:46:53,160
Built of the same stuff.
838
00:46:57,800 --> 00:47:01,540
At the start of their
lives, each harbored oceans,
839
00:47:04,280 --> 00:47:06,830
and atmospheres laden with water vapor.
840
00:47:16,570 --> 00:47:20,880
Over time, one increasingly draped itself
841
00:47:20,880 --> 00:47:22,850
in the greens and blues of life.
842
00:47:28,410 --> 00:47:32,340
While the other became
enshrouded in a toxic haze.
843
00:47:37,430 --> 00:47:40,920
Its surface paved over
with volcanic outpourings.
844
00:47:48,820 --> 00:47:53,260
Which type of world is
most common in the cosmos?
845
00:47:58,620 --> 00:48:00,520
- We know a lot about Mars.
846
00:48:00,520 --> 00:48:02,640
We've sent a dozen probes to Mars.
847
00:48:02,640 --> 00:48:05,370
We've sent rovers across the surface.
848
00:48:05,370 --> 00:48:07,920
But Venus, we have very
little knowledge of,
849
00:48:09,210 --> 00:48:12,480
so we need to start
learning how to go to Venus.
850
00:48:12,480 --> 00:48:14,270
Learn about the circulation of Venus,
851
00:48:14,270 --> 00:48:17,480
learn about the climate,
learn about the weather.
852
00:48:18,770 --> 00:48:21,210
Venus needs to be not the forgotten planet
853
00:48:21,210 --> 00:48:22,530
in the solar system.
854
00:48:24,130 --> 00:48:27,940
If we understand Venus,
we learn about the Earth.
855
00:48:27,940 --> 00:48:31,110
(soft dramatic music)
856
00:48:34,010 --> 00:48:38,050
- I imagine, imaged with the
right kind of whatever drone
857
00:48:38,050 --> 00:48:41,840
or spacecraft or even humans
ultimately going there
858
00:48:41,840 --> 00:48:44,140
in very well-protected suits,
859
00:48:44,140 --> 00:48:46,540
when we get to see it in the right way,
860
00:48:46,540 --> 00:48:48,610
we're gonna be like, "Wow, nobody told us.
861
00:48:48,607 --> 00:48:51,507
"This place is beautiful
and it's massive."
862
00:48:51,510 --> 00:48:53,840
Remember, there's much
more land area on Venus
863
00:48:53,840 --> 00:48:57,030
than there is on Earth since
Earth is two-thirds ocean,
864
00:48:57,030 --> 00:49:00,290
and it's going to be just a
thrilling place to explore fully
865
00:49:00,290 --> 00:49:01,400
when we get the opportunity.
866
00:49:01,398 --> 00:49:04,568
(soft dramatic music)
867
00:49:11,785 --> 00:49:14,285
(light music)
63887
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