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(bright music)

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I've always been really fascinated by Venus.

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because it's kind of an alternate Earth.

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Some people consider Venus

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to be a sister planet to the Earth.

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or perhaps a twin, but if it is,

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it's really an evil twin.

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I don't think it's evil,

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but it's a remarkably different twin.

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Earth's nearest planetary neighbor

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is an enigma.

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Venus has these incredibly thick clouds

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that you can't really see through.

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This is what makes it shine like a beacon in the sky.

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Actually, sometimes people think it's a UFO

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because it's so bright in the sky.

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Humans have looked at Venus

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and been drawn to it for millennia.

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To me, it's very haunting, very rich with lessons,

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and creates this desire to really understand that planet.

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But to begin to understand Venus,

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we have to go there.

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(dramatic music)

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It's definitely mysterious,

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and it's, of course, important for science.

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(people chatting)

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But it became clear that Venus is a little bit easier

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for the Soviet Union to explore for propaganda success.

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(man speaks in foreign language)

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And understanding Venus,

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could be key to our very survival.

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It's about the same radius as Earth.

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It was formed, more or less, the same place

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in the solar system than Earth.

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Perhaps our evolution is going

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to look like Venus in the future.

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We can't claim to understand Earth really

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if we don't understand Venus.

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(bright theatrical music)

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(gentle music)

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For centuries people wondered if this

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was what the surface of Venus looked like.

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Once we realized that the other planets

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were, in fact, planets, the natural assumption

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was that, well, they're probably similar,

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(gentle music)

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Venus was one of the first objects

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of scientific exploration for Russian science.

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Lomonosov, who is kind of father of Russian science,

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was the first astronomer

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who actually studied the atmosphere of Venus.

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We figured out the reason why Venus is so bright,

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and, apparently, featureless,

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is because it's completely covered in clouds.

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Naturally, we assume these are clouds of water

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like on the Earth, in which case,

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Venus would be a great swampy paradise,

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lots of water on the surface,

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and water in the atmosphere,

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totally covered by clouds.

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People imagine great lizards

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and dinosaurs living and swimming in the lakes

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and oceans the tropical forests of Venus.

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(dramatic music)

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Svante Arrhenius who was a brilliant Swedish chemist,

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was one of the first people to actually model

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scientifically what the climate of Venus was like.

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But he also had ideas about the life on Venus

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and the vegetation.

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He made observations that he thought confirmed this,

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so he actually had a kind of scientific view,

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but with a lot of imagination filling in the blanks

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that promoted this idea of Venus

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as a planet with a lot of vegetation

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and a lot of life that was similar to Earth.

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But maybe also Earth sort of stuck in the past,

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in an earlier age when Earth was sort of a swamp planet.

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(dramatic music)

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(birds chirping)

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The only way to tell actually whether Venus was

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a sort of living world with jungles on the surface

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was to actually go there with spacecraft.

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(dramatic music)

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(thunder roaring)

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But before 1975,

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no human had ever seen an image

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from the surface of another planet, let alone Venus.

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However, a Russian mission called Venera 9 was on its way.

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On 20th of October of 1975,

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this joint stock of spacecraft,

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of Lander and the Orbiter approached Venus

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and separated from each other.

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Immediately they started their separate missions,

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which were culminating at the same time.

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The Orbiter approached Venus

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and started a breaking maneuver

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with its entrance to slow down at speeds just enough

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that the gravity field of Venus would capture it

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and leave it in a highly-stretched elliptical orbit

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around the planet.

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This components of the Venera 9 spacecraft

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had become the first manmade object

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to enter orbit around Venus.

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(bright theatrical music)

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But the mission was far from over.

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And at the same time,

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the Lander started going into the atmosphere

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of Venus on the side of the planet,

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which was not visible from Earth,

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but sensed to the Orbiter,

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which was so high in the sky over Venus,

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it would later act as a lay station for the Lander

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to send pictures back to mission control on Earth.

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The Lander was a bowl-shaped capsule

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covered with a special ablative surface,

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and once it entered the atmosphere of Venus

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and started breaking, layer by layer,

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burning ablative surface,

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and at the same time slowing down

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tremendously from its initial entry speed.

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The searing heat shield decelerated the Lander

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from 10.7 kilometers per second

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to around 250 meters per second.

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(bright theatrical music)

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Then once it's slowed down enough,

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it was safe enough to open small opening

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at the top of the capsule

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and release two small breaking parachutes.

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One of those two parachutes was then used

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to release the top part of the capsule

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and reveal the top of the Lander,

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which was inside of that cocoon.

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(bright theatrical music)

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The speed dropped from 250 meters per second

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to 150 meters per second

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before a third parachute was deployed.

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And once that happened, there was an antenna,

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a transmission antenna exposed,

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and that allowed it to immediately start transmitting

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data to the Orbiter, which in turn,

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relayed back to the ground control.

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The third parachute brought the velocity

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of the Lander down to just 50 meters per second.

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And then that parachute was separated,

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and it pulls out three canopy main parachute system,

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which allows the Lander really slow and gentle descent.

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After all the drama of it's journey so far,

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the Lander would then spend 20 minutes

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calmly taking measurements of the atmosphere,

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but its brutal voyage was not over yet.

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When the probe is around 50 kilometers over the surface,

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the command is sent to cut the main lines of the parachute.

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(gentle dramatic music)

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Venus has always been a special object of fascination

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as long as we've been observing the sky,

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which is probably longer than we've been people,

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and there's a reason for that.

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It's so bright.

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It's the brightest object

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other than the full moon at night.

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For much of human history,

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we've mistaken Venus for a star or two stars to be precise,

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the morning star and the evening star.

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It appears as an evening star

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for a little while near the horizon

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and then disappears and then reappears

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as a morning star near the horizon.

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Does this intricate little dance in the sky

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and then disappears again.

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So it bounces from evening to morning.

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It's never up in the middle of the night.

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It's always at the dusk and dawn,

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which are the most evocative times.

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That has led it to be an object of mythology,

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and folklore, and with gods and goddesses.

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The association of Venus with femininity

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really comes out of the fact

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that we're still very dominated

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by Greek and Roman Western traditions.

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But, in fact, that's just one tradition,

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and if you look around the world,

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for instance, the Meso Americans

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who were probably the greatest Venus observers

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in terms of what they figured out

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about how to predict the motions and everything,

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for those civilizations,

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Venus was this macho warrior dude,

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and it was very much a male character.

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So why assign a gender to a planet?

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Planet's are at least as complex as people.

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So, I think, it maybe does do it a bit of a disservice

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just to say Venus is the female planet.

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(gentle music)

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After the II World War,

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it wasn't long before the Soviet Union stunned the world

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with the launch of Sputnik in 1957.

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A year later the U.S. launched its first spacecraft.

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The space race had begun.

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(dramatic music)

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The space race was driven by several major factors.

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First of all, it was a military competition

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of two superpowers which emerged after World War II,

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the United States and the Soviet Union,

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and the second is this ideological competition

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between two systems, socialism in the Soviet Union,

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and capitalism, as at least Soviet Union saw it.

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That competition included scientific pursuit.

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In the world of science probably the best way

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to prove that superiority would be with victories in space,

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and the Soviet government understood this.

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Space exploration has a dark side.

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We can't deny that we rode to the moon

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and to the other planets on the wings of war.

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That the reason we have these rockets

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that can launch payloads into orbit and beyond

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is because they were developed to destroy cities.

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(bomb explodes)

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The emergence of rocket technology immediately gives

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scientists this idea that you can put

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scientific instruments on the rocket

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and fly them first to the upper atmospheres, then to space,

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and then into deep space all across the solar system.

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But within the Soviet Union,

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it was in the framework of testing

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intercontinental ballistic missiles and weapons systems.

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It was absolutely under the same level of secrecy.

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There was absolutely no public.

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This was absolutely top secret.

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We didn't use the term spacecraft in those days.

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We called the payloads because

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everything went on top of a launch vehicle.

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Main thing you put on top of the launch vehicle

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was the warhead, which was the payload.

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The idea was we're really

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trying to develop a launch vehicle.

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The payload was sort of insignificant addition

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back in those days.

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What happened early on in

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the space race is we began to say,

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"Hey, the solar system let's explore it,"

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and our competitors, the former Soviet Union,

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was doing the same thing.

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Now they happened to have set their sights on Venus

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really, really hard.

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(dramatic music)

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The initial motivation for the

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Soviet space program was propaganda success.

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The ideas about Venus as a tropical paradise

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were not at play in a process of decision

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to fly spacecraft to Venus.

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Its definitely mysterious,

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and it's, of course, important for science.

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But the most important factor was

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that it's easier to reach than Mars.

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The rocket scientists in the early space race

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concluded that in order to get to Venus there's a window

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of time in which the planets are closest.

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This occurs every 19 months.

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From the moment the race to Venus began in 1961,

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only three opportunities were missed until 1986.

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First off the mark was the Soviets'

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Tyazhely Sputnik in February 1961.

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It failed to leave low-Earth orbit.

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Venera 1 became the first spacecraft to fly past Venus.

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But due to a communications failure, no data were received.

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(dramatic music)

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The early history of trying to get to Venus

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is full of failure.

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There were a lot more failures than successes.

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Within weeks of the first two attempts

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00:12:06,710 --> 00:12:08,780
to send a spacecraft to Venus,

272
00:12:08,780 --> 00:12:12,380
a discovery from an Earth-based radio telescope

273
00:12:12,380 --> 00:12:15,730
increased the intrigue about our mysterious twin.

274
00:12:15,730 --> 00:12:16,880
(dramatic music)

275
00:12:16,880 --> 00:12:20,810
Venus was found to have a very odd rotation.

276
00:12:20,810 --> 00:12:25,300
The planets seemed to be rotating backwards very slowly.

277
00:12:25,300 --> 00:12:29,500
A day on Venus is longer than its year.

278
00:12:29,500 --> 00:12:32,350
You could say why does Venus rotate backwards?

279
00:12:32,350 --> 00:12:33,720
But you can also say why do all

280
00:12:33,720 --> 00:12:35,570
the other planets rotate forwards?

281
00:12:35,570 --> 00:12:36,560
I mean, it's a mystery.

282
00:12:36,560 --> 00:12:39,030
We don't really understand Venus' rotation rate,

283
00:12:39,030 --> 00:12:40,800
but we don't really understand the rotation rates

284
00:12:40,800 --> 00:12:42,281
of the planets in general.

285
00:12:42,281 --> 00:12:43,630
(dramatic music)

286
00:12:43,630 --> 00:12:45,430
Eighteen months after the discovery

287
00:12:45,430 --> 00:12:47,860
of Venus' peculiar rotation,

288
00:12:47,860 --> 00:12:51,163
the next opportunity to get to Venus was approaching.

289
00:12:52,153 --> 00:12:53,500
(gentle dramatic music)

290
00:12:53,500 --> 00:12:56,420
In the second half of summer of 1962,

291
00:12:56,420 --> 00:12:58,890
all these forces finally came together.

292
00:12:58,890 --> 00:13:01,780
Both sides finally had the rockets necessary to launch.

293
00:13:01,780 --> 00:13:03,350
They had the spacecraft,

294
00:13:03,350 --> 00:13:06,067
which was sophisticated enough to go to Venus,

295
00:13:06,067 --> 00:13:08,220
and they had this motivation, money,

296
00:13:08,220 --> 00:13:10,860
and all the political rationale to do this.

297
00:13:10,860 --> 00:13:13,290
So within this short period of time,

298
00:13:13,290 --> 00:13:15,690
from July to beginning of September,

299
00:13:15,690 --> 00:13:18,630
there were five missions launched, two Mariner probes

300
00:13:18,630 --> 00:13:21,623
and three Russian MV probes as they were called.

301
00:13:22,780 --> 00:13:25,210
Mariners 1 and 2 were identical,

302
00:13:25,210 --> 00:13:27,500
and they were both modified Ranger spacecraft

303
00:13:27,500 --> 00:13:29,330
taken off the product line

304
00:13:29,330 --> 00:13:32,410
and converted for a mission to Venus

305
00:13:32,410 --> 00:13:35,431
rather than a Ranger mission to the moon.

306
00:13:35,431 --> 00:13:36,860
(gentle dramatic music)

307
00:13:36,860 --> 00:13:38,730
They were hexagonal in the shape

308
00:13:38,730 --> 00:13:41,230
about six boxes bolted onto a frame.

309
00:13:41,230 --> 00:13:43,200
There was a high-gain antenna,

310
00:13:43,200 --> 00:13:44,690
and there was a tower structure

311
00:13:44,690 --> 00:13:46,750
bolted on top of this hexagonal.

312
00:13:46,750 --> 00:13:47,993
We called it a bus.

313
00:13:49,100 --> 00:13:53,810
It wasn't at all unusual to be working 56 hours a week,

314
00:13:53,810 --> 00:13:56,000
and if that meant everybody had to work weekends

315
00:13:56,000 --> 00:13:59,810
or something like that or 16-hour days,

316
00:13:59,810 --> 00:14:02,150
we did it for the time that it took

317
00:14:02,150 --> 00:14:03,939
to get back on that schedule.

318
00:14:03,939 --> 00:14:05,140
(dramatic music)

319
00:14:05,140 --> 00:14:08,290
On the 22nd of July 1962,

320
00:14:08,290 --> 00:14:10,400
Mariner 1 launched,

321
00:14:10,400 --> 00:14:12,730
buts the spacecraft malfunctioned,

322
00:14:12,730 --> 00:14:15,653
and flight control had to manually destroy it.

323
00:14:16,650 --> 00:14:20,329
A month later, the first Soviet spacecraft called

324
00:14:20,329 --> 00:14:25,310
2MV-1 Number One succeeded in getting into orbit.

325
00:14:25,310 --> 00:14:27,910
But it's upper stage rocket booster failed,

326
00:14:27,910 --> 00:14:30,556
and it never left low Earth orbit.

327
00:14:30,556 --> 00:14:32,490
(dramatic music)

328
00:14:32,490 --> 00:14:35,140
Two days later, Mariner 2

329
00:14:35,140 --> 00:14:38,116
blasted off successfully from Cape Canaveral,

330
00:14:38,116 --> 00:14:39,520
(dramatic music)

331
00:14:39,520 --> 00:14:42,670
followed by the final two Soviet spacecraft

332
00:14:42,670 --> 00:14:45,193
on the 1st and 12th of September.

333
00:14:46,220 --> 00:14:49,253
Both failed to leave Earth's orbit.

334
00:14:49,253 --> 00:14:50,580
(dramatic music)

335
00:14:50,580 --> 00:14:54,934
Three months later on the 14th of December 1962,

336
00:14:54,934 --> 00:14:58,170
(bright music)

337
00:14:58,170 --> 00:15:01,053
Mariner 2 arrived safely at Venus.

338
00:15:04,119 --> 00:15:06,410
Mariner 2 became the first spacecraft

339
00:15:06,410 --> 00:15:09,210
to explore another planet in the solar system

340
00:15:09,210 --> 00:15:12,150
and actually return useful scientific data

341
00:15:12,150 --> 00:15:14,122
from the vicinity of another planet.

342
00:15:14,122 --> 00:15:16,705
(bright music)

343
00:15:20,670 --> 00:15:21,840
(gentle music)

344
00:15:21,840 --> 00:15:24,170
The measurement that Mariner 2 made

345
00:15:24,170 --> 00:15:28,430
suggested that the upper atmosphere of Venus was very hot

346
00:15:28,430 --> 00:15:32,030
in the region of 500 degrees celsius.

347
00:15:32,030 --> 00:15:33,810
Perhaps Venus wasn't quite

348
00:15:33,810 --> 00:15:36,167
the paradise everyone had hoped for.

349
00:15:37,860 --> 00:15:40,040
There was an editorial in the New York Times

350
00:15:40,040 --> 00:15:43,530
when the Mariner 2 results were reported,

351
00:15:43,530 --> 00:15:46,387
and it was titled "Venus Says No",

352
00:15:47,460 --> 00:15:51,230
and it talks about the grand romantic dreams

353
00:15:51,230 --> 00:15:53,563
of mankind being dashed.

354
00:15:56,330 --> 00:15:57,840
Mariner 2 also made

355
00:15:57,840 --> 00:16:00,220
another startling discovery.

356
00:16:00,220 --> 00:16:03,623
It could be a hint that all was not well with Earth's twin.

357
00:16:04,850 --> 00:16:06,200
Unlike our planet,

358
00:16:06,200 --> 00:16:08,830
with its North and South magnetic poles,

359
00:16:08,830 --> 00:16:12,043
Venus doesn't have any significant magnetic field.

360
00:16:13,980 --> 00:16:16,010
It's about the same radius as Earth.

361
00:16:16,010 --> 00:16:18,720
It's roughly the same rotation, right?

362
00:16:18,720 --> 00:16:21,870
Maybe it's a hundred times slower,

363
00:16:21,870 --> 00:16:24,790
but that's not that different, fluid dynamics wise.

364
00:16:24,790 --> 00:16:26,870
These are still rapidly rotating bodies.

365
00:16:26,870 --> 00:16:28,500
It's got a big core we believe.

366
00:16:28,500 --> 00:16:29,810
We believe it's molten.

367
00:16:29,810 --> 00:16:32,513
Something's funny that Venus has no dynamo.

368
00:16:34,290 --> 00:16:38,287
Mariner 2 took measurements of high temperatures on Venus,

369
00:16:38,287 --> 00:16:41,420
and there was a dispute about those temperatures,

370
00:16:41,420 --> 00:16:43,830
perhaps being only high in the atmosphere

371
00:16:43,830 --> 00:16:46,710
or the temperatures really showing an unbearably

372
00:16:46,710 --> 00:16:50,560
hot environment everywhere around the planet.

373
00:16:50,560 --> 00:16:53,390
So, of course, the immediate challenge was after this,

374
00:16:53,390 --> 00:16:56,290
both for the Soviet Union and for the American scientists

375
00:16:56,290 --> 00:16:59,210
was to launch more probes, more sophisticated ones,

376
00:16:59,210 --> 00:17:02,930
but design them based on all of the available information

377
00:17:02,930 --> 00:17:06,282
and continue this pursuit of what Venus is all about.

378
00:17:06,282 --> 00:17:08,227
(dramatic music)

379
00:17:08,227 --> 00:17:10,240
Mariner 2s distant flyby

380
00:17:10,240 --> 00:17:13,820
hadn't settled the score for supremacy over Venus,

381
00:17:13,820 --> 00:17:16,840
but the USA and the USSR were about to begin

382
00:17:16,840 --> 00:17:20,780
an even more intense battle for Earth's twin.

383
00:17:20,780 --> 00:17:24,070
From now on once Mariner 2 did the job,

384
00:17:24,070 --> 00:17:27,200
it was absolutely paramount for the Soviet Union

385
00:17:27,200 --> 00:17:29,630
to land on the surface of Venus first

386
00:17:29,630 --> 00:17:31,990
and preferably to do imagery

387
00:17:31,990 --> 00:17:34,660
and science on the surface of Venus.

388
00:17:34,660 --> 00:17:36,440
Over the next 11 years,

389
00:17:36,440 --> 00:17:39,141
there was a frenzy of missions to Venus

390
00:17:39,141 --> 00:17:42,808
(dramatic theatrical music)

391
00:17:48,271 --> 00:17:51,938
(bright lighthearted music)

392
00:17:54,870 --> 00:17:57,400
Venera 9 is plangently increasingly

393
00:17:57,400 --> 00:17:59,093
dense atmosphere of Venus.

394
00:17:59,093 --> 00:18:00,590
(bright theatrical music)

395
00:18:00,590 --> 00:18:03,610
About 50 kilometers up from the surface of Venus,

396
00:18:03,610 --> 00:18:07,670
you pass through a region that is about

397
00:18:07,670 --> 00:18:11,200
the surface temperature and pressure of Earth,

398
00:18:11,200 --> 00:18:13,850
so there's a region in the upper atmosphere of Venus

399
00:18:13,850 --> 00:18:17,300
that would feel pretty much like it feels in this room.

400
00:18:17,300 --> 00:18:19,320
I think to any individual

401
00:18:19,320 --> 00:18:22,670
who reads the description of the landing sequence,

402
00:18:22,670 --> 00:18:24,230
thinks that it's really irrational

403
00:18:24,230 --> 00:18:26,610
and a really bizarre way to get

404
00:18:26,610 --> 00:18:28,660
equipment to the surface of Venus,

405
00:18:28,660 --> 00:18:31,530
But after a little bit close examination,

406
00:18:31,530 --> 00:18:33,420
we understand that each steps of the sequence

407
00:18:33,420 --> 00:18:35,860
there's actually logic and behind it.

408
00:18:35,860 --> 00:18:38,020
And, in fact, it's counterintuitive,

409
00:18:38,020 --> 00:18:41,100
but part of the problem with a lot of designs

410
00:18:41,100 --> 00:18:43,740
when you're designing an entry probe for Venus

411
00:18:43,740 --> 00:18:45,500
is that you fall too slowly,

412
00:18:45,500 --> 00:18:47,540
Meaning that, it takes too long,

413
00:18:47,540 --> 00:18:48,850
and you're gonna heat up too much

414
00:18:48,850 --> 00:18:50,350
before you get to the surface.

415
00:18:54,100 --> 00:18:55,330
Then you keep falling,

416
00:18:55,330 --> 00:18:57,270
and the atmosphere gets hotter and hotter

417
00:18:57,270 --> 00:19:00,570
and more and more dense to the point where

418
00:19:00,570 --> 00:19:04,850
it's a hundred times as dense as the atmosphere on Earth.

419
00:19:04,850 --> 00:19:07,100
That means that you're falling through.

420
00:19:07,100 --> 00:19:09,190
It's not quite a liquid, but it's a gas

421
00:19:09,190 --> 00:19:11,400
that is approaching the properties of a liquid,

422
00:19:11,400 --> 00:19:13,117
and that would slow your fall.

423
00:19:13,117 --> 00:19:15,840
(voice chattering on radio)

424
00:19:15,840 --> 00:19:16,960
Then when you get to the surface,

425
00:19:16,960 --> 00:19:18,913
it's almost like going through the ocean.

426
00:19:18,913 --> 00:19:20,470
(gentle music)

427
00:19:20,470 --> 00:19:22,540
Venera 9 wasn't the first Lander

428
00:19:22,540 --> 00:19:24,313
to get to the surface of Venus,

429
00:19:25,278 --> 00:19:27,913
but it was the first to send back pictures.

430
00:19:29,580 --> 00:19:31,805
It was a colossal achievement.

431
00:19:31,805 --> 00:19:35,222
(gentle dramatic music)

432
00:19:37,420 --> 00:19:40,240
Venera 9 returned the first pictures

433
00:19:40,240 --> 00:19:43,000
from the surface of another planet,

434
00:19:43,000 --> 00:19:45,650
and the fact that, that was done first for Venus

435
00:19:45,650 --> 00:19:50,160
before the Americans did it with a Viking in 1976 at Mars

436
00:19:50,160 --> 00:19:52,990
is really remarkable because it's much harder to land

437
00:19:52,990 --> 00:19:56,410
on Venus and photograph it than it is on Mars.

438
00:19:56,410 --> 00:19:58,370
Not that Mars is a picnic,

439
00:19:58,370 --> 00:20:00,880
but just to get something to survive

440
00:20:00,880 --> 00:20:03,330
in those conditions and take a photograph

441
00:20:03,330 --> 00:20:06,730
and send the results back is really challenging.

442
00:20:06,730 --> 00:20:10,770
That achievement in 1975 by the Soviet Union

443
00:20:10,770 --> 00:20:13,886
that was a real triumph of exploration.

444
00:20:13,886 --> 00:20:16,640
(gentle music)

445
00:20:16,640 --> 00:20:19,900
What we have from the Russian is just unbelievable

446
00:20:19,900 --> 00:20:23,030
because it was really a challenge to land there.

447
00:20:23,030 --> 00:20:25,460
So even if the images are not perfect,

448
00:20:25,460 --> 00:20:27,397
it's still wonderful.

449
00:20:29,157 --> 00:20:33,300
But the ideas of Venus as a verdant lovely environment,

450
00:20:33,300 --> 00:20:35,400
possibly with jungles on the surface

451
00:20:35,400 --> 00:20:39,223
and a water rich environment, were immediately taken away.

452
00:20:41,685 --> 00:20:43,610
It wasn't really until Venera 9

453
00:20:43,610 --> 00:20:45,660
operated at the surface for some time

454
00:20:45,660 --> 00:20:48,450
and returned data that we were sure that we had

455
00:20:48,450 --> 00:20:50,870
solid data that told us, yes, this is how hot

456
00:20:50,870 --> 00:20:52,240
and this is what the pressure.

457
00:20:52,240 --> 00:20:54,543
Wow, that's really pretty intense.

458
00:20:54,543 --> 00:20:56,164
(dramatic music)

459
00:20:56,164 --> 00:20:57,640
(thunder roaring)

460
00:20:57,640 --> 00:21:01,030
After Venera 9, we had a sense

461
00:21:01,030 --> 00:21:05,520
of what some individual places on Venus were like.

462
00:21:05,520 --> 00:21:07,270
If you send a probe in one place

463
00:21:07,270 --> 00:21:08,240
and you measure the temperature

464
00:21:08,240 --> 00:21:09,750
and pressure on the way down,

465
00:21:09,750 --> 00:21:14,130
it gives you one slice from space to the surface.

466
00:21:14,130 --> 00:21:16,620
But the more we learned about Venus,

467
00:21:16,620 --> 00:21:18,370
the more we realize that

468
00:21:18,370 --> 00:21:20,920
like Earth it's a complex changing planet

469
00:21:20,920 --> 00:21:22,910
with different things going on in the day side

470
00:21:22,910 --> 00:21:25,750
and the night side and this latitude and that latitude,

471
00:21:25,750 --> 00:21:29,050
and that to really understand what's going on,

472
00:21:29,050 --> 00:21:32,070
you have to measure multiple places at once.

473
00:21:32,070 --> 00:21:34,370
If you have this probe on the night side,

474
00:21:34,370 --> 00:21:35,650
and this probe on the day side,

475
00:21:35,650 --> 00:21:36,920
and this probe at high latitude,

476
00:21:36,920 --> 00:21:38,380
and this probe at low latitude

477
00:21:38,380 --> 00:21:40,680
and you're able to do them all at once,

478
00:21:40,680 --> 00:21:44,010
then you can put together more of a 3D picture

479
00:21:44,010 --> 00:21:45,830
of the way the atmosphere is behaving

480
00:21:45,830 --> 00:21:47,313
and changing over time.

481
00:21:48,710 --> 00:21:51,080
In 1974, NASA approved

482
00:21:51,080 --> 00:21:53,480
a double mission to explore Venus,

483
00:21:53,480 --> 00:21:58,030
both from orbit and from multiple places around the planet.

484
00:21:58,030 --> 00:22:01,923
This ambitious mission was called Pioneer Venus,

485
00:22:03,340 --> 00:22:06,210
The Pioneer Venus mission included an Orbiter

486
00:22:06,210 --> 00:22:09,460
and four probes, three small probes

487
00:22:09,460 --> 00:22:11,040
and one large probe to look

488
00:22:11,040 --> 00:22:13,900
at different parts of the global Venus

489
00:22:13,900 --> 00:22:17,193
and to make measurements as they descended to the surface.

490
00:22:18,320 --> 00:22:20,110
The Pioneer Venus Orbiter

491
00:22:20,110 --> 00:22:22,810
launched in May in 1978,

492
00:22:22,810 --> 00:22:25,050
and the spacecraft carrying the probes

493
00:22:25,050 --> 00:22:26,940
followed it in August.

494
00:22:26,940 --> 00:22:30,160
The Orbiter had arrived at Venus a few days earlier

495
00:22:30,160 --> 00:22:33,300
and inserted itself into orbit in preparation

496
00:22:33,300 --> 00:22:37,180
to relay data back from atmospheric probes.

497
00:22:37,180 --> 00:22:41,270
The probes were not designed to survive the landing,

498
00:22:41,270 --> 00:22:43,730
but fortunately one did

499
00:22:43,730 --> 00:22:46,170
and continued to send back information

500
00:22:46,170 --> 00:22:49,853
until the heat of the surface destroyed its electronics.

501
00:22:51,290 --> 00:22:52,123
The results from the

502
00:22:52,123 --> 00:22:54,550
Pioneer Venus mission were clear.

503
00:22:54,550 --> 00:22:56,710
No matter where you went on Venus,

504
00:22:56,710 --> 00:22:58,840
the night side, the day side,

505
00:22:58,840 --> 00:23:01,470
the equator, or the higher latitudes,

506
00:23:01,470 --> 00:23:05,463
its surface was uniformly hot and at high pressure.

507
00:23:07,690 --> 00:23:09,210
So Venus is all bad.

508
00:23:09,210 --> 00:23:11,170
The temperature only varies by a degree

509
00:23:11,170 --> 00:23:12,960
or two over the whole globe,

510
00:23:12,960 --> 00:23:15,940
day to night, pole to equator,

511
00:23:15,940 --> 00:23:19,740
and the thick atmosphere acts like a blanket,

512
00:23:19,740 --> 00:23:24,000
which keeps the entire surface of Venus very hot,

513
00:23:24,000 --> 00:23:26,140
and so there's no place,

514
00:23:26,140 --> 00:23:29,150
no hospitable place on the surface of Venus,

515
00:23:29,150 --> 00:23:31,623
where we might imagine humans living.

516
00:23:33,060 --> 00:23:34,980
It's not just the temperature.

517
00:23:34,980 --> 00:23:37,390
The atmospheric pressure on the surface

518
00:23:37,390 --> 00:23:40,480
is so high that it would crush almost

519
00:23:40,480 --> 00:23:42,903
every military submarine ever built.

520
00:23:43,990 --> 00:23:47,830
Now we see Venus is just awful environment.

521
00:23:47,830 --> 00:23:49,460
I mean the atmosphere is only

522
00:23:49,460 --> 00:23:52,993
CO2 is 90 bars on the surface and 500 degrees.

523
00:23:54,350 --> 00:23:55,800
By the end of the '70s,

524
00:23:55,800 --> 00:23:58,760
we really understood how Venus looked.

525
00:23:58,760 --> 00:24:01,830
I mean, it was not gonna be habitable.

526
00:24:01,830 --> 00:24:04,680
And to me that had sort of a lingering effect

527
00:24:04,680 --> 00:24:07,190
that Venus was like not as exciting

528
00:24:07,190 --> 00:24:08,500
as it was supposed to be,

529
00:24:08,500 --> 00:24:10,850
and, therefore, it was sort of not as cool

530
00:24:10,850 --> 00:24:13,560
and maybe not as worthy of our attention.

531
00:24:13,560 --> 00:24:15,060
I think that was really unfortunate

532
00:24:15,060 --> 00:24:17,020
because it was an outcome of those

533
00:24:17,020 --> 00:24:19,510
false expectations that we had for it.

534
00:24:19,510 --> 00:24:23,840
So instead of Venus being a sort of tropical paradise,

535
00:24:23,840 --> 00:24:26,400
it's hell things have gone terribly bad.

536
00:24:26,400 --> 00:24:29,530
Temperature on the surface is hot enough to melt lead

537
00:24:29,530 --> 00:24:32,430
and the atmosphere is full of poisonous gases

538
00:24:32,430 --> 00:24:33,905
and carbon dioxide.

539
00:24:33,905 --> 00:24:36,488
(gentle music)

540
00:24:38,020 --> 00:24:40,180
It sets up this huge mystery.

541
00:24:40,180 --> 00:24:43,600
Why do you have these twin planets so nearby,

542
00:24:43,600 --> 00:24:45,752
and one of them ends up like this,

543
00:24:45,752 --> 00:24:49,320
this paradise for Earthly life.

544
00:24:49,320 --> 00:24:53,564
This other one right here ends up in such a different state.

545
00:24:53,564 --> 00:24:56,270
What happened there,

546
00:24:56,270 --> 00:24:57,933
and can that happen here?

547
00:24:58,930 --> 00:25:00,770
If we don't know the answer to that,

548
00:25:00,770 --> 00:25:03,093
how much do we really know about our planet?

549
00:25:03,093 --> 00:25:05,676
(gentle music)

550
00:25:07,570 --> 00:25:09,600
In order to answer these questions,

551
00:25:09,600 --> 00:25:14,112
we must go back to the formation of Venus and Earth.

552
00:25:14,112 --> 00:25:16,862
(dramatic music)

553
00:25:19,110 --> 00:25:21,720
Earth and Venus form this set of twins

554
00:25:21,720 --> 00:25:23,960
that, as far as we can tell, started out more similar,

555
00:25:23,960 --> 00:25:25,960
and then diverged.

556
00:25:25,960 --> 00:25:27,770
Understanding that divergence

557
00:25:27,770 --> 00:25:29,480
is an important scientific puzzle,

558
00:25:29,480 --> 00:25:31,550
but it's also just sort of compelling

559
00:25:31,550 --> 00:25:32,770
because Earth is our home,

560
00:25:32,770 --> 00:25:34,320
and here's this other planet

561
00:25:34,320 --> 00:25:36,570
that could have been like Earth, that should have been,

562
00:25:36,570 --> 00:25:39,680
and yet it's so different.

563
00:25:39,680 --> 00:25:41,880
(dramatic music)

564
00:25:41,880 --> 00:25:43,067
The formation of Venus and Earth

565
00:25:43,067 --> 00:25:44,553
was probably pretty similar.

566
00:25:44,553 --> 00:25:47,740
It's made of the same type of stuff.

567
00:25:47,740 --> 00:25:50,280
It seems as though the original rocky stuff

568
00:25:50,280 --> 00:25:52,820
that fell together and made Earth

569
00:25:52,820 --> 00:25:55,480
probably had a lot of water bound up in it,

570
00:25:55,480 --> 00:25:58,880
and Venus because it seems to have been made out of

571
00:25:58,880 --> 00:26:02,650
the same stuff in the same process at the same time,

572
00:26:02,650 --> 00:26:05,490
then likely got a similar admixture of water

573
00:26:05,490 --> 00:26:08,690
just chemically bound up in that rocky material

574
00:26:08,690 --> 00:26:10,190
that made the original planet.

575
00:26:11,330 --> 00:26:12,850
About 600 million years

576
00:26:12,850 --> 00:26:14,490
after the beginning of the solar system,

577
00:26:14,490 --> 00:26:16,850
there was a very large period of collisions

578
00:26:16,850 --> 00:26:18,800
when the collision rate was very high,

579
00:26:18,800 --> 00:26:20,850
and that's what we call the late heavy bombardment.

580
00:26:20,850 --> 00:26:22,240
So during that time,

581
00:26:22,240 --> 00:26:24,750
there were both comets and asteroids moving around

582
00:26:24,750 --> 00:26:28,458
both bringing even more water to the Earth and Venus.

583
00:26:28,458 --> 00:26:31,320
(gentle music)

584
00:26:31,320 --> 00:26:32,850
After all the brutal drama

585
00:26:32,850 --> 00:26:34,520
of the initial formation

586
00:26:34,520 --> 00:26:37,283
and the violence of the late heavy bombardment,

587
00:26:38,720 --> 00:26:41,660
things would have settled down for Earth and Venus.

588
00:26:41,660 --> 00:26:44,243
(gentle music)

589
00:26:45,230 --> 00:26:48,580
Venus might've been much more hospitable,

590
00:26:48,580 --> 00:26:49,970
very similar to the Earth.

591
00:26:49,970 --> 00:26:53,027
Maybe there were oceans and even life on Venus.

592
00:26:53,027 --> 00:26:55,610
(gentle music)

593
00:27:05,170 --> 00:27:09,420
So why is it that Earth today is an oceanic planet

594
00:27:09,420 --> 00:27:12,830
and Venus is not if they both started out similar?

595
00:27:12,830 --> 00:27:15,190
The one obvious difference is that Venus

596
00:27:15,190 --> 00:27:17,300
is significantly closer to the Sun.

597
00:27:17,300 --> 00:27:18,530
It's about three quarters

598
00:27:18,530 --> 00:27:20,180
of the distance from the Sun to Earth,

599
00:27:20,180 --> 00:27:23,060
which means it gets about twice the amount of sunlight.

600
00:27:23,060 --> 00:27:24,690
When the planets were young,

601
00:27:24,690 --> 00:27:27,100
the Sun was much less bright than it is now.

602
00:27:27,100 --> 00:27:29,080
So there was a time when the ocean of Venus

603
00:27:29,080 --> 00:27:30,203
was probably stable.

604
00:27:32,150 --> 00:27:36,190
What happened we think was that as the Sun heated up,

605
00:27:36,190 --> 00:27:39,063
it triggered something we call the runaway greenhouse,

606
00:27:41,230 --> 00:27:44,130
and the way that works has to do with evaporation.

607
00:27:44,130 --> 00:27:46,420
So if you're evaporating the oceans of a planet,

608
00:27:46,420 --> 00:27:48,447
you're getting more water vapor in the atmosphere.

609
00:27:48,447 --> 00:27:51,720
But water vapor itself is a strong greenhouse gas,

610
00:27:51,720 --> 00:27:53,270
really as strong as CO2,

611
00:27:53,270 --> 00:27:56,450
meaning that it's a gas that absorbs infrared radiation.

612
00:27:56,450 --> 00:27:58,170
It lets the visible through.

613
00:27:58,170 --> 00:27:59,950
It absorbs infrared.

614
00:27:59,950 --> 00:28:02,260
So you get more water vapor,

615
00:28:02,260 --> 00:28:03,300
you're absorbing more infrared.

616
00:28:03,300 --> 00:28:06,710
You have a stronger greenhouse that heats up the surface.

617
00:28:06,710 --> 00:28:09,570
so you get more evaporation and more evaporation,

618
00:28:09,570 --> 00:28:11,680
gives you more water vapor in the atmosphere

619
00:28:11,680 --> 00:28:15,330
a stronger greenhouse, hotter surface, more evaporation.

620
00:28:15,330 --> 00:28:17,450
So you can see it's what we call positive feedback

621
00:28:17,450 --> 00:28:19,200
because the hotter the surface is,

622
00:28:19,200 --> 00:28:20,817
the more water vapor you're getting in the atmosphere.

623
00:28:20,817 --> 00:28:23,160
The more water vapor, the hotter the surface is,

624
00:28:23,160 --> 00:28:25,640
so that each part of the cycle reinforces the other.

625
00:28:25,640 --> 00:28:27,930
That's a positive feedback and that's unstable.

626
00:28:27,930 --> 00:28:29,328
It runs away.

627
00:28:29,328 --> 00:28:32,090
(gentle music)

628
00:28:32,090 --> 00:28:35,130
So water in the oceans evaporated

629
00:28:35,130 --> 00:28:37,060
to make a blanket around the planet,

630
00:28:37,060 --> 00:28:39,970
which made the planet hotter, but worse than that,

631
00:28:39,970 --> 00:28:42,876
carbon dioxide was baked out of rocks.

632
00:28:42,876 --> 00:28:45,330
(dramatic music)

633
00:28:45,330 --> 00:28:47,440
The idea that carbon dioxide

634
00:28:47,440 --> 00:28:50,910
could create a powerful greenhouse effect goes all

635
00:28:50,910 --> 00:28:54,723
the way back to the Swedish pioneer Svante Arrhenius.

636
00:28:55,870 --> 00:28:58,380
Svante Arrhenius correctly deduced

637
00:28:58,380 --> 00:29:01,420
that there was a lot of carbon dioxide in the atmosphere.

638
00:29:01,420 --> 00:29:02,840
So it was probably hot.

639
00:29:02,840 --> 00:29:04,620
In fact, he was also one of the first people

640
00:29:04,620 --> 00:29:07,890
that considered greenhouse warming on Earth.

641
00:29:07,890 --> 00:29:10,280
Interestingly, and that partly came out of his work

642
00:29:10,280 --> 00:29:12,470
on thinking about what Venus was like.

643
00:29:12,470 --> 00:29:14,130
So this is one of the ways, in which,

644
00:29:14,130 --> 00:29:15,720
our knowledge of Earth climate

645
00:29:15,720 --> 00:29:18,590
and global warming is actually connected to thought

646
00:29:18,590 --> 00:29:20,970
about Venus because Arrhenius put this together.

647
00:29:20,970 --> 00:29:23,739
He said a planet with a lot of CO2 has to be warm.

648
00:29:23,739 --> 00:29:25,500
(bright music)

649
00:29:25,500 --> 00:29:28,440
So how did Earth escape the same fate

650
00:29:28,440 --> 00:29:32,230
as Venus with a runaway greenhouse effect?

651
00:29:32,230 --> 00:29:34,703
The answer begins with rain.

652
00:29:35,760 --> 00:29:39,380
So on Earth the CO2 gets pulled out of the atmosphere

653
00:29:39,380 --> 00:29:41,270
by what we call weathering reactions,

654
00:29:41,270 --> 00:29:43,520
where water is raining out

655
00:29:43,520 --> 00:29:45,470
and makes a sort of carbonic acid,

656
00:29:45,470 --> 00:29:49,410
which when it runs over rocks, leaches the ions out

657
00:29:49,410 --> 00:29:52,010
and it ends up in the ocean as carbonate ions

658
00:29:52,010 --> 00:29:53,903
and forms carbonate rocks.

659
00:29:55,210 --> 00:29:56,710
When you see the White Cliffs of Dover

660
00:29:56,710 --> 00:30:00,100
or any massive deposit of carbonates,

661
00:30:00,100 --> 00:30:01,610
you're seeing carbon that has been

662
00:30:01,610 --> 00:30:03,890
pulled out of the atmosphere.

663
00:30:03,890 --> 00:30:05,650
Those carbonate rocks get pulled

664
00:30:05,650 --> 00:30:07,520
into the interior by plate tectonics,

665
00:30:07,520 --> 00:30:10,270
and when you have subduction of oceanic crust

666
00:30:10,270 --> 00:30:13,010
down deep into the interior where they're melted

667
00:30:13,010 --> 00:30:17,020
and ultimately then the CO2 is released under pressure

668
00:30:17,020 --> 00:30:18,760
and becomes a dissolved gas,

669
00:30:18,760 --> 00:30:20,740
which then comes back out those volcanoes

670
00:30:20,740 --> 00:30:22,190
and that completes the cycle.

671
00:30:23,210 --> 00:30:26,590
But that is facilitated by water in rain

672
00:30:26,590 --> 00:30:28,070
and in these chemical reactions.

673
00:30:28,070 --> 00:30:29,270
If you don't have water,

674
00:30:29,270 --> 00:30:31,361
you sort of break that part of the carbon cycle.

675
00:30:31,361 --> 00:30:33,687
(gentle dramatic music)

676
00:30:33,687 --> 00:30:35,390
But if the process that removes

677
00:30:35,390 --> 00:30:38,710
carbon dioxide from the atmosphere is rain,

678
00:30:38,710 --> 00:30:41,200
what happened to Venus' water.

679
00:30:41,200 --> 00:30:43,760
The answer is due to a complex interaction

680
00:30:43,760 --> 00:30:47,290
of the planet's atmosphere and the stream of particles

681
00:30:47,290 --> 00:30:50,623
that constantly come off the Sun called the solar wind.

682
00:30:53,460 --> 00:30:55,480
When the water on a planet evaporates

683
00:30:55,480 --> 00:30:57,430
and is in the atmosphere as water vapor

684
00:30:57,430 --> 00:31:01,130
as opposed to condensed on the surface in liquid water,

685
00:31:01,130 --> 00:31:03,947
then it's much more vulnerable being lost to space,

686
00:31:03,947 --> 00:31:05,800
and the main way that happens

687
00:31:05,800 --> 00:31:09,440
is the water gets broken up by ultraviolet light

688
00:31:09,440 --> 00:31:11,090
in what we call photo dissociation,

689
00:31:11,090 --> 00:31:13,690
which is that these energetic photons of sunlight

690
00:31:13,690 --> 00:31:16,990
breaks hydrogens off from the oxygen.

691
00:31:16,990 --> 00:31:18,900
Then when you have a free floating hydrogen,

692
00:31:18,900 --> 00:31:21,080
it's easy for that to escape into space.

693
00:31:21,080 --> 00:31:22,720
In fact, all planets are losing hydrogen

694
00:31:22,720 --> 00:31:24,200
all the time into space,

695
00:31:24,200 --> 00:31:26,027
and when you have a steam atmosphere

696
00:31:26,027 --> 00:31:28,790
and a lot of water photo dissociating,

697
00:31:28,790 --> 00:31:30,530
then you're gonna have a stream of hydrogen

698
00:31:30,530 --> 00:31:32,200
escaping off into space.

699
00:31:32,200 --> 00:31:33,480
Then after a period of time,

700
00:31:33,480 --> 00:31:34,710
you're left with less hydrogen,

701
00:31:34,710 --> 00:31:36,350
and, therefore, less water on the planet.

702
00:31:36,350 --> 00:31:37,680
The solar wind is a stream

703
00:31:37,680 --> 00:31:40,060
of charged particles coming out of the Sun.

704
00:31:40,060 --> 00:31:41,920
That is what is stripping away

705
00:31:41,920 --> 00:31:43,860
the atmospheres of the planets.

706
00:31:43,860 --> 00:31:46,540
All this means that you're sort of losing water,

707
00:31:46,540 --> 00:31:49,130
and so Venus is becoming drier and drier.

708
00:31:49,130 --> 00:31:51,340
So Earth has a magnetic field which protects it

709
00:31:51,340 --> 00:31:54,000
to some extent from the onslaught of the solar wind.

710
00:31:54,000 --> 00:31:56,010
Whereas, Venus we have no magnetic field

711
00:31:56,010 --> 00:31:57,560
to protect the planet.

712
00:31:57,560 --> 00:31:59,830
A decade or so ago people used to think

713
00:31:59,830 --> 00:32:02,940
that the big difference between Earth and Venus

714
00:32:02,940 --> 00:32:05,250
was that the Earth had a magnetic field,

715
00:32:05,250 --> 00:32:07,560
and then we looked at Venus and we said

716
00:32:07,560 --> 00:32:08,810
it's lost all its water

717
00:32:08,810 --> 00:32:10,910
because solar wind strips it away.

718
00:32:10,910 --> 00:32:13,230
We are finding it's more subtle now.

719
00:32:13,230 --> 00:32:14,950
Pretty much all of the planets

720
00:32:14,950 --> 00:32:18,600
lose their atmosphere right now at about the same rate,

721
00:32:18,600 --> 00:32:20,470
so everything's scrambled.

722
00:32:20,470 --> 00:32:22,080
We're back to the drawing board

723
00:32:22,080 --> 00:32:26,360
to really try to understand how atmospheric escape what,

724
00:32:26,360 --> 00:32:27,870
and what role, if any,

725
00:32:27,870 --> 00:32:30,213
the magnetic field plays in that process.

726
00:32:31,500 --> 00:32:33,910
Whether or not the lack of a magnetic field

727
00:32:33,910 --> 00:32:36,970
had accelerated the loss of Venus' water.

728
00:32:36,970 --> 00:32:39,070
The planet became dry

729
00:32:39,070 --> 00:32:41,737
and had no chance to mop up all the CO2.

730
00:32:43,740 --> 00:32:45,387
(gentle music)

731
00:32:45,387 --> 00:32:48,085
But where did all this gas come from?

732
00:32:48,085 --> 00:32:49,470
(gentle music)

733
00:32:49,470 --> 00:32:51,790
Why was the atmosphere of Venus

734
00:32:51,790 --> 00:32:54,350
so much thicker than our own?

735
00:32:54,350 --> 00:32:56,410
To find out, scientists would need

736
00:32:56,410 --> 00:32:59,203
to find a way to see what was going on.

737
00:33:01,090 --> 00:33:02,440
One of the fantastic things

738
00:33:02,440 --> 00:33:04,450
about Venus is its cloud layer.

739
00:33:04,450 --> 00:33:07,130
This is what makes it shine like a beacon in the sky.

740
00:33:07,130 --> 00:33:09,900
At the same time, it's one of the most frustrating things

741
00:33:09,900 --> 00:33:12,320
because it stops us seeing the surface.

742
00:33:12,320 --> 00:33:14,470
So what we need to do is not look with our eyes

743
00:33:14,470 --> 00:33:16,260
but look with different wavelengths

744
00:33:16,260 --> 00:33:17,790
that can peer through these clouds

745
00:33:17,790 --> 00:33:20,910
and get down to the surface, such as radar wave lengths,

746
00:33:20,910 --> 00:33:23,210
and then we can certainly see what's going on.

747
00:33:25,870 --> 00:33:29,893
After the success of Venera 9 and 10 in 1975,

748
00:33:31,590 --> 00:33:33,510
the Soviets continued to send

749
00:33:33,510 --> 00:33:35,573
a variety of missions to Venus.

750
00:33:36,538 --> 00:33:39,121
(gentle music)

751
00:33:48,557 --> 00:33:51,400
But NASA was determined to try and find out

752
00:33:51,400 --> 00:33:54,483
what much of the surface of Venus actually looked like,

753
00:33:55,686 --> 00:33:57,020
and in the early '80s,

754
00:33:57,020 --> 00:33:59,633
they started to develop a mission to do that,

755
00:34:00,890 --> 00:34:04,140
called the Venus Orbiting Imaging Radar.

756
00:34:04,140 --> 00:34:06,030
(gentle music)

757
00:34:06,030 --> 00:34:09,960
It had multiple instruments and multiple antennas

758
00:34:09,960 --> 00:34:13,090
and NASA said there's no money.

759
00:34:13,090 --> 00:34:18,090
And so, this great thing narrowed down to one instrument,

760
00:34:18,570 --> 00:34:20,400
and we were a spare parts mission.

761
00:34:20,400 --> 00:34:22,550
We used a Voyager spare antenna,

762
00:34:22,550 --> 00:34:26,710
and a Voyager spare bus, and Galileo computers,

763
00:34:26,710 --> 00:34:29,520
but the radar itself was a new design.

764
00:34:29,520 --> 00:34:31,310
It had this parabolic antenna,

765
00:34:31,310 --> 00:34:34,530
so the signal would ping off Venus and come back,

766
00:34:34,530 --> 00:34:36,230
and you'd have to capture it.

767
00:34:36,230 --> 00:34:38,010
You synthesize an image from that.

768
00:34:38,010 --> 00:34:39,380
You do it over, and over, and over again,

769
00:34:39,380 --> 00:34:43,730
and you gradually build up radar images of the surface.

770
00:34:43,730 --> 00:34:45,390
The budget version of the mission

771
00:34:45,390 --> 00:34:49,163
made from old spare parts was renamed Magellan,

772
00:34:51,410 --> 00:34:54,570
and on the 4th of May 1989,

773
00:34:54,570 --> 00:34:55,807
it was delivered to low Earth orbit.

774
00:34:55,807 --> 00:34:57,620
12, 11.
(funky music)

775
00:34:57,620 --> 00:34:59,590
By space shuttle Atlantis.

776
00:34:59,590 --> 00:35:01,579
Zero, and lift off.

777
00:35:01,579 --> 00:35:04,616
(funky electric music)

778
00:35:04,616 --> 00:35:07,520
There's the Orbiter going by the launch tower.

779
00:35:07,520 --> 00:35:10,390
The last one seems to be throttle down.

780
00:35:11,630 --> 00:35:15,430
So the design of Magellan was to get into an orbit.

781
00:35:15,430 --> 00:35:18,370
If Venus is here, it would go by really close

782
00:35:18,370 --> 00:35:20,930
for an hour and radar image,

783
00:35:20,930 --> 00:35:22,580
and then it would turn back to the Earth

784
00:35:22,580 --> 00:35:25,250
and relay back its data for another hour.

785
00:35:25,250 --> 00:35:28,520
And then it would correct its wheels and get a star scan,

786
00:35:28,520 --> 00:35:31,420
and then turn back and then radar image again,

787
00:35:31,420 --> 00:35:35,673
and we did this 24 seven for a Venus day.

788
00:35:37,577 --> 00:35:38,770
(gentle music)

789
00:35:38,770 --> 00:35:42,880
This is 1989, 1990, 1991.

790
00:35:42,880 --> 00:35:45,420
We're dealing with reel to reel tapes,

791
00:35:45,420 --> 00:35:47,160
and they're running these tapes

792
00:35:47,160 --> 00:35:48,840
back and forth from Goldstone.

793
00:35:48,840 --> 00:35:52,560
And then the data from Canberra and from Madrid

794
00:35:52,560 --> 00:35:56,530
would actually be flown in in overseas packages.

795
00:35:56,530 --> 00:35:58,610
The extreme efforts that the scientists

796
00:35:58,610 --> 00:36:02,980
and engineers made to acquire this data was worth it.

797
00:36:02,980 --> 00:36:05,860
Magellan provided an unprecedented view

798
00:36:05,860 --> 00:36:07,653
of the Venusian surface.

799
00:36:09,230 --> 00:36:11,407
They mapped near to the entire surface of Venus

800
00:36:11,407 --> 00:36:13,520
and that was a huge revelation

801
00:36:13,520 --> 00:36:16,040
because that was our first global look at

802
00:36:16,040 --> 00:36:18,090
what the geology of Venus is really like.

803
00:36:20,500 --> 00:36:23,250
The Magellan data was indisputable.

804
00:36:23,250 --> 00:36:28,163
Venus is or was a world of volcanoes of all kinds.

805
00:36:29,520 --> 00:36:31,940
It told us, yes, this is a world that's dominated

806
00:36:31,940 --> 00:36:34,810
by vulcanism has been through much of its history.

807
00:36:34,810 --> 00:36:35,643
(dramatic music)

808
00:36:35,643 --> 00:36:37,680
It's a world that has been

809
00:36:37,680 --> 00:36:40,514
resurfaced by volcanism over time.

810
00:36:40,514 --> 00:36:42,060
(dramatic music)

811
00:36:42,060 --> 00:36:43,750
There's a huge abundance

812
00:36:43,750 --> 00:36:46,733
and variety of volcanism on Venus.

813
00:36:47,570 --> 00:36:49,640
There are these huge areas of flood basalts

814
00:36:49,640 --> 00:36:52,160
where this running lava has come out from the interior,

815
00:36:52,160 --> 00:36:54,091
and a lot of Venus is covered with that.

816
00:36:54,091 --> 00:36:56,146
(suspenseful music)

817
00:36:56,146 --> 00:36:58,010
But then there are other volcanic features,

818
00:36:58,010 --> 00:37:00,020
these things nicknamed pancake domes,

819
00:37:00,020 --> 00:37:01,080
which are much smaller.

820
00:37:01,080 --> 00:37:03,120
They're about 10 kilometers across

821
00:37:03,120 --> 00:37:05,650
because they're much more sticky,

822
00:37:05,650 --> 00:37:08,264
less runny, more viscous magma.

823
00:37:08,264 --> 00:37:10,040
(suspenseful music)

824
00:37:10,040 --> 00:37:13,200
So it's been a volcanically active planet massively

825
00:37:13,200 --> 00:37:15,390
with all different kinds of volcanism

826
00:37:15,390 --> 00:37:17,050
going through many different phases.

827
00:37:17,050 --> 00:37:18,300
Now it doesn't mean that it's current.

828
00:37:18,300 --> 00:37:19,363
It could be ancient.

829
00:37:22,680 --> 00:37:25,110
All of this activity means that Venus

830
00:37:25,110 --> 00:37:28,520
has been belching carbon dioxide into its atmosphere

831
00:37:28,520 --> 00:37:30,263
for billions of years,

832
00:37:31,400 --> 00:37:34,520
and with no rain to absorb the CO2,

833
00:37:34,520 --> 00:37:37,599
the atmosphere has become thicker and thicker.

834
00:37:37,599 --> 00:37:39,869
(gentle music)

835
00:37:39,869 --> 00:37:42,950
(thunder roars)

836
00:37:42,950 --> 00:37:46,430
The atmosphere on Venus today is almost all CO2

837
00:37:46,430 --> 00:37:47,850
and here on Earth we're concerned

838
00:37:47,850 --> 00:37:51,070
about 300, 400 parts per million CO2.

839
00:37:51,070 --> 00:37:52,020
It's a trace gas.

840
00:37:52,020 --> 00:37:53,336
It's a minor gas.

841
00:37:53,336 --> 00:37:55,919
(gentle music)

842
00:37:59,890 --> 00:38:02,990
If we assume that Venus and Earth started out similar,

843
00:38:02,990 --> 00:38:04,120
which I think is likely,

844
00:38:04,120 --> 00:38:06,230
although we still wanna gather the data to prove it,

845
00:38:06,230 --> 00:38:09,380
that Venus had early oceans more like Earth

846
00:38:09,380 --> 00:38:11,330
and had some kind of a tectonic cycle

847
00:38:11,330 --> 00:38:13,240
and probably a carbon cycle with carbonates

848
00:38:13,240 --> 00:38:16,738
and volcanoes like Earth has today, then what happened?

849
00:38:16,738 --> 00:38:18,720
(dramatic music)
(thunder rumbling)

850
00:38:18,720 --> 00:38:20,440
Why is the solid part of the planet

851
00:38:20,440 --> 00:38:22,700
the geology apparently so different from Earth's?

852
00:38:22,700 --> 00:38:25,290
And in my view, it probably has to do

853
00:38:25,290 --> 00:38:27,770
with the losing of the water.

854
00:38:27,770 --> 00:38:31,610
That if you lose the water from the surface of the planet,

855
00:38:31,610 --> 00:38:34,580
then over time you're going to also dry out the crust

856
00:38:34,580 --> 00:38:36,080
and the interior of the planet

857
00:38:36,080 --> 00:38:38,650
because you are also out gassing water.

858
00:38:38,650 --> 00:38:40,530
You're losing water through that cycle,

859
00:38:40,530 --> 00:38:43,640
and on Earth you're in gassing water too,

860
00:38:43,640 --> 00:38:46,270
in the sense that, you're pulling water into the interior

861
00:38:46,270 --> 00:38:48,740
all the time through that tectonic cycle.

862
00:38:48,740 --> 00:38:51,230
If you lose that ability to do that

863
00:38:51,230 --> 00:38:53,090
because you don't have any water on the surface,

864
00:38:53,090 --> 00:38:54,390
you're not going to right away

865
00:38:54,390 --> 00:38:56,310
dry out the interior of the planet.

866
00:38:56,310 --> 00:38:58,720
But after a billion, two billion years,

867
00:38:58,720 --> 00:39:00,330
you're going to ultimately end up with

868
00:39:00,330 --> 00:39:02,680
a dried out interior and a dried out crust,

869
00:39:02,680 --> 00:39:05,550
and that's going to have different material properties.

870
00:39:05,550 --> 00:39:08,920
And, in fact, if you take an Earth model of plate tectonics

871
00:39:08,920 --> 00:39:12,540
and mantle convection and you dry it out,

872
00:39:12,540 --> 00:39:14,927
you change the properties of the rocks and say,

873
00:39:14,927 --> 00:39:16,217
"Well, what if these were dry rocks

874
00:39:16,217 --> 00:39:18,500
"instead of hydrated rocks,"

875
00:39:18,500 --> 00:39:21,260
these models will start behaving more like Venus.

876
00:39:21,260 --> 00:39:22,520
The rocks get harder.

877
00:39:22,520 --> 00:39:24,270
It gets harder to subduct.

878
00:39:24,270 --> 00:39:26,400
Plate tectonics gets sort of choked off,

879
00:39:26,400 --> 00:39:28,670
and it's like the engine runs out of lubrication

880
00:39:28,670 --> 00:39:32,630
and it gets stuck and then starts going in spurts

881
00:39:32,630 --> 00:39:34,626
rather than running smoothly.

882
00:39:34,626 --> 00:39:35,800
(gentle dramatic music)

883
00:39:35,800 --> 00:39:38,040
And this drying up of the crust

884
00:39:38,040 --> 00:39:39,960
could be responsible for the lack of

885
00:39:39,960 --> 00:39:42,600
what's known as an internal dynamo,

886
00:39:42,600 --> 00:39:45,144
which is what produces a magnetic field.

887
00:39:45,144 --> 00:39:48,160
(gentle music)

888
00:39:48,160 --> 00:39:50,030
I think the easiest explanation

889
00:39:50,030 --> 00:39:52,320
for why Venus doesn't have a dynamo

890
00:39:52,320 --> 00:39:56,400
is probably that heat is trapped within the core.

891
00:39:56,400 --> 00:39:57,810
It appears right now

892
00:39:57,810 --> 00:40:00,180
that there's no plate tectonics on Venus.

893
00:40:00,180 --> 00:40:03,150
There's probably convection occurring within the mantle,

894
00:40:03,150 --> 00:40:06,170
but it's not very efficient at getting heat out,

895
00:40:06,170 --> 00:40:08,880
and so that probably traps heat within the core.

896
00:40:08,880 --> 00:40:10,650
If heat can't get out,

897
00:40:10,650 --> 00:40:14,010
then I can't cool that fluid at the surface.

898
00:40:14,010 --> 00:40:16,700
I can't release those dense blobs

899
00:40:16,700 --> 00:40:19,450
into the interior falling and convecting.

900
00:40:19,450 --> 00:40:22,330
If it's not convecting and there's none of that

901
00:40:22,330 --> 00:40:25,363
turbulent convection to stir up a magnetic field,

902
00:40:26,200 --> 00:40:29,470
I think you should then see what you do see.

903
00:40:29,470 --> 00:40:30,610
(gentle music)

904
00:40:30,610 --> 00:40:32,120
Magellan orbited Venus

905
00:40:32,120 --> 00:40:36,143
from August 1990 until October 1994.

906
00:40:37,950 --> 00:40:41,320
The mission mapped 98% of the surface

907
00:40:41,320 --> 00:40:44,010
and greatly increased our understanding

908
00:40:44,010 --> 00:40:45,700
of the geological processes

909
00:40:45,700 --> 00:40:47,772
that have shaped the planet's history.

910
00:40:47,772 --> 00:40:48,960
(gentle music)

911
00:40:48,960 --> 00:40:52,070
And by that time, it was done.

912
00:40:52,070 --> 00:40:54,160
The computers were resetting.

913
00:40:54,160 --> 00:40:55,610
We were out of fuel,

914
00:40:55,610 --> 00:40:57,280
and then you gotta update

915
00:40:57,280 --> 00:40:59,010
because now your timing's off

916
00:40:59,010 --> 00:41:00,850
because you've got slightly out of orbit

917
00:41:00,850 --> 00:41:02,830
because of your thrusters.

918
00:41:02,830 --> 00:41:06,090
It was always an engineering challenge

919
00:41:06,090 --> 00:41:08,580
because I was just scrambling every day

920
00:41:08,580 --> 00:41:10,270
just to keep it going.

921
00:41:10,270 --> 00:41:14,030
But it was a great spacecraft to be your first spacecraft

922
00:41:14,030 --> 00:41:17,662
because it was a hell of a learning experience for me.

923
00:41:17,662 --> 00:41:20,440
(gentle music)

924
00:41:20,440 --> 00:41:22,130
The last communication with

925
00:41:22,130 --> 00:41:26,360
Magellan was on the 13th of October 1994,

926
00:41:26,360 --> 00:41:28,880
before the spacecraft disintegrated

927
00:41:28,880 --> 00:41:31,927
deep in Venus's thick atmosphere.

928
00:41:31,927 --> 00:41:33,440
In the aftermath of Magellan,

929
00:41:33,440 --> 00:41:36,160
there was a lot of desire for more Venus missions,

930
00:41:36,160 --> 00:41:39,690
and a lot of frustration in the community of the inability

931
00:41:39,690 --> 00:41:42,520
to get NASA to send another mission to Venus,

932
00:41:42,520 --> 00:41:44,520
which is a effort that continues.

933
00:41:44,520 --> 00:41:45,890
But the European sort of came

934
00:41:45,890 --> 00:41:48,130
to our rescue with Venus Express.

935
00:41:48,130 --> 00:41:51,010
It's called Venus Express because

936
00:41:51,010 --> 00:41:53,640
it was a mission that was put together very quickly.

937
00:41:53,640 --> 00:41:55,850
There was a spare spacecraft from another mission,

938
00:41:55,850 --> 00:41:58,350
and they had a couple of years to propose

939
00:41:58,350 --> 00:42:00,600
and fly a spacecraft, and the Venus Express Mission

940
00:42:00,600 --> 00:42:02,410
was the one that won.

941
00:42:02,410 --> 00:42:04,750
What Venus Express really is, I think of it

942
00:42:04,750 --> 00:42:07,374
as our first weather satellite at another planet.

943
00:42:07,374 --> 00:42:10,290
(gentle dramatic music)

944
00:42:10,290 --> 00:42:13,280
And as the first Venusian weather satellites

945
00:42:13,280 --> 00:42:16,040
Venus express gave us a much greater insight

946
00:42:16,040 --> 00:42:20,190
into what was really going on with Venus's atmosphere.

947
00:42:20,190 --> 00:42:22,700
(dramatic music)

948
00:42:22,700 --> 00:42:26,880
So Venus Express made these movies of the motions

949
00:42:26,880 --> 00:42:28,520
of the atmosphere at different depths,

950
00:42:28,520 --> 00:42:30,380
and indeed it's quite dynamic.

951
00:42:30,380 --> 00:42:31,840
The atmosphere of Venus does this,

952
00:42:31,840 --> 00:42:33,830
what we call four days super rotation,

953
00:42:33,830 --> 00:42:35,830
where the atmosphere is whipping around.

954
00:42:37,540 --> 00:42:40,320
These high altitude zonal winds

955
00:42:40,320 --> 00:42:42,840
can zip around the equator of Venus

956
00:42:42,840 --> 00:42:46,120
at 360 kilometers per hour.

957
00:42:46,120 --> 00:42:47,400
But above the poles,

958
00:42:47,400 --> 00:42:50,840
the rotational speeds drop almost to zero.

959
00:42:50,840 --> 00:42:53,440
(dramatic music)

960
00:42:53,440 --> 00:42:55,870
The intense heat on the surface of Venus

961
00:42:55,870 --> 00:42:58,620
creates powerful convection currents

962
00:42:58,620 --> 00:43:01,780
that drive a separate lower altitude circulation

963
00:43:01,780 --> 00:43:04,830
of heat from the equator to the poles.

964
00:43:04,830 --> 00:43:07,370
(dramatic music)

965
00:43:07,370 --> 00:43:10,790
With Venus Express we saw these vortices near the poles,

966
00:43:10,790 --> 00:43:12,480
in particular the South Pole of Venus,

967
00:43:12,480 --> 00:43:14,073
which had not been seen before.

968
00:43:14,073 --> 00:43:16,020
There's a little bit of like water down a bath plug,

969
00:43:16,020 --> 00:43:18,673
so seeing that for the first time was very exciting.

970
00:43:20,420 --> 00:43:22,840
Venus is entirely covered by clouds.

971
00:43:22,840 --> 00:43:26,390
These clouds are made up of droplets of sulfuric acid,

972
00:43:26,390 --> 00:43:28,770
so it's arguably the case that Venus

973
00:43:28,770 --> 00:43:33,320
has the worst case of acid rain in the whole solar system.

974
00:43:33,320 --> 00:43:36,020
The acid rain of Venus is created by the

975
00:43:36,020 --> 00:43:39,690
vast amounts of sulfur released through the vulcanism

976
00:43:39,690 --> 00:43:42,023
that has dominated the planet's evolution.

977
00:43:43,630 --> 00:43:46,770
Acid rain is in an extreme state on Venus.

978
00:43:46,770 --> 00:43:49,540
Acid rain has been a problem on Earth downwind of factories,

979
00:43:49,540 --> 00:43:52,430
and by studying it in an extreme case on another planet,

980
00:43:52,430 --> 00:43:53,760
it helps us understand more of the

981
00:43:53,760 --> 00:43:56,630
interaction of acid with water clouds.

982
00:43:56,630 --> 00:43:59,060
But down at the surface of Venus,

983
00:43:59,060 --> 00:44:03,751
things are altogether much calmer and deeply weird.

984
00:44:03,751 --> 00:44:05,630
(gentle music)

985
00:44:05,630 --> 00:44:08,850
Here the wind speeds are very low.

986
00:44:08,850 --> 00:44:10,720
The acid rain has evaporated

987
00:44:10,720 --> 00:44:13,321
long before it gets this far down.

988
00:44:13,321 --> 00:44:16,010
(gentle music)

989
00:44:16,010 --> 00:44:18,330
If you could go to the surface of Venus,

990
00:44:18,330 --> 00:44:19,990
not that we can right now,

991
00:44:19,990 --> 00:44:22,713
I think it would be an incredibly strange experience.

992
00:44:23,550 --> 00:44:24,820
The first thing you would notice is that

993
00:44:24,820 --> 00:44:26,580
the quality of light would be very different

994
00:44:26,580 --> 00:44:28,540
from the quality of light on Earth,

995
00:44:28,540 --> 00:44:31,010
and that's mostly because the light is being filtered

996
00:44:31,010 --> 00:44:33,040
through that incredibly thick atmosphere

997
00:44:33,040 --> 00:44:36,160
and also through the globally extensive clouds.

998
00:44:36,160 --> 00:44:39,763
So it would be kind of a red murky light.

999
00:44:40,620 --> 00:44:41,720
When you look at things,

1000
00:44:41,720 --> 00:44:45,500
you're looking through this massively convective medium

1001
00:44:45,500 --> 00:44:47,827
where because of the temperature you're looking at,

1002
00:44:47,827 --> 00:44:51,749
and the swells and stuff, you see the refraction of light.

1003
00:44:51,749 --> 00:44:54,560
(dramatic music)

1004
00:44:54,560 --> 00:44:56,840
You probably would see that sort of shimmery

1005
00:44:56,840 --> 00:44:59,640
kind of effect that you get in desert areas on Earth

1006
00:44:59,640 --> 00:45:02,020
just because there is a lot of infrared radiation

1007
00:45:02,020 --> 00:45:02,997
coming up out of the surface,

1008
00:45:02,997 --> 00:45:04,690
and that is going to be affecting

1009
00:45:04,690 --> 00:45:07,603
the stability of the atmosphere near the surface.

1010
00:45:10,857 --> 00:45:13,660
You're in this really, really strange environment.

1011
00:45:13,660 --> 00:45:15,890
Any movement you feel resistance,

1012
00:45:15,890 --> 00:45:19,300
and it becomes this viscous fluid-like thing

1013
00:45:19,300 --> 00:45:21,840
that you're having to move through.

1014
00:45:21,840 --> 00:45:23,990
It wouldn't be quite like running through water,

1015
00:45:23,990 --> 00:45:25,210
but you'd be approaching that.

1016
00:45:25,210 --> 00:45:26,200
You'd be somewhere in between

1017
00:45:26,200 --> 00:45:28,470
what we feel running through the air

1018
00:45:28,470 --> 00:45:31,020
and that resistance of trying to run

1019
00:45:31,020 --> 00:45:32,670
through something really viscous.

1020
00:45:32,670 --> 00:45:34,932
It'd be a good workout that's for sure.

1021
00:45:34,932 --> 00:45:37,970
(dramatic music)

1022
00:45:37,970 --> 00:45:40,030
So in the future,

1023
00:45:40,030 --> 00:45:42,250
will there ever be a time when Venus

1024
00:45:42,250 --> 00:45:44,690
might've cleared its dense atmosphere

1025
00:45:44,690 --> 00:45:47,963
and cold enough for humans to live on its surface?

1026
00:45:49,220 --> 00:45:51,370
Some have proposed that Venus might

1027
00:45:51,370 --> 00:45:54,600
once again be hospitable, and potentially

1028
00:45:54,600 --> 00:45:58,410
after volcanic eruptions cease on the surface of Venus.

1029
00:45:58,410 --> 00:45:59,840
I don't buy that.

1030
00:45:59,840 --> 00:46:02,930
I think, the escape rate of the Venus atmosphere

1031
00:46:02,930 --> 00:46:06,670
over time is infinitesimally slow

1032
00:46:06,670 --> 00:46:09,140
compared to the magnitude of the atmosphere.

1033
00:46:09,140 --> 00:46:11,910
The time it might take for the Venus atmosphere

1034
00:46:11,910 --> 00:46:13,540
to be cured in that way,

1035
00:46:13,540 --> 00:46:16,230
would probably match the time that the Sun

1036
00:46:16,230 --> 00:46:18,920
would take to see out the rest of its lifetime,

1037
00:46:18,920 --> 00:46:22,793
swelling into a red giant and engulfing the whole planet.

1038
00:46:25,240 --> 00:46:28,610
So there's really no future time that I can imagine

1039
00:46:28,610 --> 00:46:31,250
where the atmosphere would be lost enough

1040
00:46:31,250 --> 00:46:34,150
so the greenhouse effect would be small enough

1041
00:46:34,150 --> 00:46:37,710
so the surface temperature of Venus would be cool enough

1042
00:46:37,710 --> 00:46:39,557
that life could exist there.

1043
00:46:39,557 --> 00:46:40,720
(thunder rumbles)

1044
00:46:40,720 --> 00:46:42,930
So if Venus is never destined to become

1045
00:46:42,930 --> 00:46:46,993
the paradise we once imagined through natural processes,

1046
00:46:46,993 --> 00:46:48,610
(gentle music)

1047
00:46:48,610 --> 00:46:51,143
what about through deliberate manipulation?

1048
00:46:52,110 --> 00:46:55,020
Can we terraform Venus?

1049
00:46:55,020 --> 00:46:57,630
Terraforming is an interesting concept.

1050
00:46:57,630 --> 00:47:00,030
It's certainly a valuable thought experiment.

1051
00:47:00,030 --> 00:47:02,810
I don't necessarily condone trying this,

1052
00:47:02,810 --> 00:47:04,070
but that's okay cause we're not gonna

1053
00:47:04,070 --> 00:47:06,180
have the ability for a long time.

1054
00:47:06,180 --> 00:47:08,090
We have millennia to sort that out,

1055
00:47:08,090 --> 00:47:09,700
whether we think it's a good idea.

1056
00:47:09,700 --> 00:47:11,340
So maybe the way to do it would be

1057
00:47:11,340 --> 00:47:13,560
to throw a lot of comets at Venus

1058
00:47:13,560 --> 00:47:16,090
where you would both raise up the dust

1059
00:47:16,090 --> 00:47:17,840
from the comet impact to cool it off,

1060
00:47:17,840 --> 00:47:18,810
and then you'd also be sort of

1061
00:47:18,810 --> 00:47:21,060
sprinkling it back with water.

1062
00:47:21,060 --> 00:47:23,070
If you start to have liquid water on the surface,

1063
00:47:23,070 --> 00:47:25,500
then that's gonna restart the cycle

1064
00:47:25,500 --> 00:47:27,120
where you're gonna then be removing

1065
00:47:27,120 --> 00:47:29,790
CO2 out of the atmosphere by weathering.

1066
00:47:29,790 --> 00:47:33,310
It would take awhile it'd build longterm renovation project,

1067
00:47:33,310 --> 00:47:36,560
but there's nothing physically impossible about it.

1068
00:47:36,560 --> 00:47:39,050
The problem with terraforming ideas is that

1069
00:47:39,050 --> 00:47:40,320
right now we're in a situation

1070
00:47:40,320 --> 00:47:42,720
where we're rapidly Venura-forming Earth,

1071
00:47:42,720 --> 00:47:44,410
that is turning it to be more Venus like,

1072
00:47:44,410 --> 00:47:46,820
and so we can't even imagine any of these futures

1073
00:47:46,820 --> 00:47:48,390
unless we get to the point where we're doing a much

1074
00:47:48,390 --> 00:47:52,235
better job of controlling our own actions on Earth.

1075
00:47:52,235 --> 00:47:55,070
(gentle music)

1076
00:47:55,070 --> 00:47:57,480
People talk about us colonizing the solar system,

1077
00:47:57,480 --> 00:48:00,890
escaping from the problems that we have on the planet Earth.

1078
00:48:00,890 --> 00:48:03,550
Maybe there's an asteroid heading towards us,

1079
00:48:03,550 --> 00:48:05,250
which one day will hit the surface

1080
00:48:05,250 --> 00:48:07,710
of the planet and cause extinction,

1081
00:48:07,710 --> 00:48:09,590
and, I think, these are things which are important.

1082
00:48:09,590 --> 00:48:11,620
We're studying them, and we really need to understand

1083
00:48:11,620 --> 00:48:14,450
what the possible longterm dangers are.

1084
00:48:14,450 --> 00:48:16,133
But there's a short-term danger,

1085
00:48:17,540 --> 00:48:18,690
which is climate change,

1086
00:48:18,690 --> 00:48:20,253
and it's happening today.

1087
00:48:21,610 --> 00:48:23,240
What worries me sometimes is this idea

1088
00:48:23,240 --> 00:48:24,920
that we can take human beings away

1089
00:48:24,920 --> 00:48:27,250
from all of the mess that we've created here.

1090
00:48:27,250 --> 00:48:29,860
Sociologically, it seems unlikely that we're just going to

1091
00:48:29,860 --> 00:48:32,520
become the perfect citizen once we crossed

1092
00:48:32,520 --> 00:48:34,900
the 100 kilometer line and go into space.

1093
00:48:34,900 --> 00:48:37,690
But also there's nowhere in the solar system

1094
00:48:37,690 --> 00:48:40,570
that's any better to live than the very worst

1095
00:48:40,570 --> 00:48:42,220
that we could ever do to the planet Earth.

1096
00:48:42,220 --> 00:48:43,930
Whatever we do here,

1097
00:48:43,930 --> 00:48:47,450
it won't be as bad as living on Mars or on Venus

1098
00:48:47,450 --> 00:48:49,190
or anywhere else in the solar system.

1099
00:48:49,190 --> 00:48:51,700
So at the same time as we're looking outwards and exploring,

1100
00:48:51,700 --> 00:48:55,440
we should never forget that this is where we come from,

1101
00:48:55,440 --> 00:48:57,670
and there is no planet B.

1102
00:48:57,670 --> 00:48:59,560
This place has to be looked after as well

1103
00:48:59,560 --> 00:49:02,643
as much as we're looking outwards and beyond.

1104
00:49:03,648 --> 00:49:04,730
(gentle music)

1105
00:49:04,730 --> 00:49:08,150
So perhaps one day, far in the future,

1106
00:49:08,150 --> 00:49:11,730
humankind will not only have the scientific ability

1107
00:49:11,730 --> 00:49:14,617
to make Venus into a paradise,

1108
00:49:14,617 --> 00:49:16,860
but the wisdom to realize

1109
00:49:16,860 --> 00:49:20,381
that we already have a paradise of our own

1110
00:49:20,381 --> 00:49:24,048
(gentle lighthearted music)

1111
00:49:26,466 --> 00:49:29,133
(bright music)