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In 1979, a robotic spacecraft
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flew by the Planet Jupiter.
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Completely unexpectedly, it
found a mysterious object
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the size of our Moon.
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The craft had observed
something almost unbelievable.
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We live on a remarkable planet.
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The rock itself is alive.
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The Earth spits out hot
lava, creating new land.
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It is a sight we can only watch in awe.
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Well, I find it absolutely
overwhelming to look
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inside a volcano like this and
see the hot lava oozing out.
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You can see that the Earth is active.
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It's like the lifeblood of the planet.
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For a geologist, like Jim Head,
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the Earth is an inspiration
to look into other worlds.
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How does all this play out
on the other planets?
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What does it look like there?
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Would there be hot lava
like this, volcanoes?
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Would we see things like ocean basins?
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We have absolutely no clue.
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The history of this planet
is written in its rocks.
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Over hundreds of millions of years,
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mountain ranges have risen up,
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entire continents have drifted apart.
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Is this how other worlds would be?
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Earth's satellite, the Moon,
could hardly be more different.
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Nothing has happened on this dusty world
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for billions of years.
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Its surface shows only the scars
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of countless impacts by asteroids.
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The surfaces of the other planets
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must also reveal clues about their past.
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But they are so far away,
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they appear just as dots
of light in the sky.
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Astronomers gazed at those dots;
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but only on one of them could
they make out anything
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that looked remotely like
the landforms of the Earth.
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It was the Red Planet of Mars.
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Over a century ago, an Italian astronomer,
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Giovanni Schiaparelli, began to chart
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the dark and light regions of Mars.
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His maps were the best we had
until space probes came along.
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In 1964, NASA launched Mariner 4.
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Its mission was to fly past Mars
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and try to send back closeup pictures.
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The mission was a technical success.
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But the fuzzy images showed
nothing particularly
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interesting, just craters,
like those on the Moon.
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But astronomers were convinced
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that the probe had looked
in the wrong place.
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Brad Smith had spent years
gazing at the Red Planet.
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He thought he knew where the
next probe should look.
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For the next mission,
NASA asked him for help.
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I have been observing
Mars for quite some time
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with ground-based telescopes,
and we had noticed
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that there were certain regions
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that were very changeable,
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they change with the seasons,
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they seem to have colors to them.
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And we thought that those would
be particularly interesting,
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so I set up the targeting
so that Mariner 6 and 7
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would look at these particular
areas during the approach.
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As Mariner 6 and 7 raced towards Mars,
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they saw what appeared to be mountains,
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dark plains, deep canyons.
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But when the closeups came back,
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Brad and NASA were once again disappointed.
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Unfortunately the surface was
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very heavily-cratered.
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There were dark and light
areas, to be sure,
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but it was still a lot
like looking at the Moon.
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Convinced that there had to be more
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than just craters on Mars,
NASA went back again.
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This time, they planned to give
the probe longer to search.
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Mariner 9 was not a quick flyby;
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it was designed to go
into orbit around Mars
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and photograph every
square foot of the Planet.
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But as the probe closed in, disaster.
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A large dust storm began to stir.
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I was watching the Planet,
hoping that it wouldn't
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be a bad one, but within
just a matter of days
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a brilliant brilliant
yellow cloud developed
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and we knew it was a bad dust storm,
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and it spread out over the entire Planet,
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covering up everything.
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But Mariner sat out the storm,
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and then, miraculously,
saw something poking up
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through the dust.
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We saw these four dark spots
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and we weren't really quite
sure what they were.
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And one of our team members had pointed out
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that there were things that looked like
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the tops of volcanoes; and
he suggested that in fact
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these were volcanoes that were so high
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that they were actually
poking up through the dust.
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As the dust began to recede,
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the four spots showed themselves.
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They were volcanoes,
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giant ones.
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The biggest of them was
christened Olympus Mons.
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It was 15 miles high,
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three times the size of Everest.
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Mars was not just another Moon;
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it was a real world;
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and geologists were eager to
compare it with the Earth.
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Jim Head went straight to the
biggest volcanoes he knew
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on the Island of Hawaii.
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I remember when Olympus Mons
first came out of the clouds
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on Mariner 9; it was
absolutely spectacular,
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this gigantic volcano.
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And I couldn't wait to
get back here to Hawaii
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to get some sense of the
perspective and scale
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from something that I knew about.
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And here we are on the
edge of this volcano,
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this incredibly large volcano,
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one of the largest on the Earth,
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and in fact it's like tiny
compared to Olympus Mons.
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To travel right across the crater
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of Olympus Mons would mean
a journey of 600 miles,
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an area the size of France.
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It's covered with crumbling red lava.
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The volcanoes were just the start.
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As the dust withdrew, Mariner 9's cameras
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snapped thousands more pictures.
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A whole new world was taking shape.
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NASA called in scientists
with a new expertise:
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planetary geologists.
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When this thing began to shape up
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and we began to see all these
features, that was the first
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time that this whole Planet Mars
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had ever really begun to
take shape in the sense
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of knowing what the physical
features were, the geology.
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None of that stuff had
ever been seen before.
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It was a historical moment,
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when you finally start,
like with an orange,
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peeling the peel off and exposing
a planet for what it is.
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As Mariner's cameras tracked across
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the Red Planet, a giant crevice appeared.
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Each day we'd get a new set of images,
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and as they mosaic, then we
say: "My god, look at that!
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"Where's it going?"
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And stretch clear across roughly
an eighth of the Planet.
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They had discovered the
biggest canyon ever seen.
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Valles Marineris is 4,000 miles across
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and maybe 100 miles at its widest
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and as much as six miles deep.
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Scale of the United States
is something like that.
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The scale of the United States I think is,
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over there would be San Francisco
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and over here would be New
York, something like that.
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So it would span the United States.
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And this little canyon right here
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is the size of the Grand Canyon.
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The Valles Marineris probably cracked open
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when the four giant volcanoes
to its north pushed up,
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breaking open the surface of the Planet.
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Martian geology is written on a scale
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that dwarfs the Earth's.
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Giant features, like Valles
Marineris and Olympus Mons,
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have been steadily growing
in the same place
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for billions of years.
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This suggested that the surface
of the Planet did not move,
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unlike the drifting
continents of the Earth.
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Mariner 9 had gone in
search of geological life
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and had found it.
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So it was a very active Planet;
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it was a planet that had
real geology, active geology
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going on even in modern geologic history.
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But was it all history?
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Was Mars a graveyard of geology
from the distant past?
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Or were the volcanoes still alive?
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To find out, a probe needed to
land on the Planet's surface.
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Jerry Soffurn was the mission's scientist.
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The whole point of Viking
is to be the first time
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you really explored the
surface of the Planet.
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The Mariners had actually
orbited, or flown by, the Planet,
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but the idea of actually getting
a lander on the surface
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of Mars, it was as important
as Columbus' voyage.
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I was absolutely terrified that we wouldn't
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land successfully because I
had spent so much of my life
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aimed at this great moment in history.
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14,000 feet.
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15,480 feet per second.
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3,000 feet.
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On July the 20th, 1976,
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Viking dropped into Mars' upper atmosphere
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and began its descent.
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8.4 Gs.
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ATS is green, 1.5 degrees per second max.
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0.2 Gs.
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Eight feet per second.
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When the landing took place,
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it was like it was two minutes ago.
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I can see every single
face and the expectation.
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The signals from Viking took 18 minutes
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to travel back to Mission Control.
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The scientists could do nothing but wait.
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And when the touchdown came,
I just exploded inside.
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Touchdown! We have touchdown!
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Yeah!
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We have touchdown.
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We're looking good.
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That is a treat.
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Copy, power.
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We're out of sync.
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The idea of being there in history
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when the first landing on Mars
took place was thrilling.
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And now, what everyone wanted to know:
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What would the surface of Mars look like?
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Was it gonna be like someplace on the US?
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Was it gonna be a desert?
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Was it gonna be sandy, or dusty?
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But all we knew is that
it was gonna be red.
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An hour after Viking landed,
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the first black-and-white
pictures began to be sent back.
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Line by line, the surface
of Mars was revealed.
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Then came color pictures.
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The surface was littered with rocks,
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some of them dark and
porous, clearly volcanic.
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They must have been hurled
there by volcanoes.
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We knew there were volcanoes on Mars but
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actually see a piece of the
volcano was just astonishing.
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But when had the pieces landed there?
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Viking carried a device to find out
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whether Mars was still active,
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a seismometer, to tell if
the ground was shaking.
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Viking listened and
waited, but felt nothing.
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For all its spectacular volcanoes
and canyons, it seemed
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that geological activity on
Mars was a thing of the past.
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While the Americans were putting
all their efforts into Mars
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the Russians headed for Venus.
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This world is almost as large as the Earth,
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and geologists had always
thought it would be our twin.
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But Venus was no easy target.
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The surface was hidden by
a thick blanket of cloud;
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but below that serene exterior
were hellish conditions.
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The pressure of the atmosphere had already
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crushed three Soviet probes.
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The Russians had found to their
cost that the temperature
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on the surface was nearly
500 degrees centigrade.
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In 1975 they tried again,
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and equipped their probe with a camera.
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They hoped it would cling on long enough
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to send back just one
picture of the surface.
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The mission chiefs didn't want anyone
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to know that it might fail.
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Seconds after landing, signals showed
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00:18:55,800 --> 00:18:58,217
Venera 9 systems were intact.
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But on the surface the temperature
was hotter than an oven.
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Would the probe survive long
enough to send back an image?
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The camera had captured a
blurred view of some rocks.
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00:19:48,273 --> 00:19:52,440
It was the first-ever image
of the surface of Venus.
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00:19:53,695 --> 00:19:56,862
But it was only a tantalizing glimpse.
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00:20:09,972 --> 00:20:11,411
With their next probe,
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00:20:11,412 --> 00:20:14,579
the Russians hoped for something more.
256
00:20:16,218 --> 00:20:19,793
On landing, all systems radioed back OK,
257
00:20:19,794 --> 00:20:22,556
but there was no image of the surface.
258
00:20:22,557 --> 00:20:24,577
Sasha Basilevski was on the team
259
00:20:24,578 --> 00:20:28,025
that tried to work out what had gone wrong.
260
00:20:28,026 --> 00:20:31,113
We had technical meeting
and there was discussion
261
00:20:31,114 --> 00:20:34,651
and chief designer that time told:
262
00:20:34,652 --> 00:20:38,401
"You know, I have an
idea that we have landed
263
00:20:38,402 --> 00:20:41,652
"in something very sticky and viscous."
264
00:20:42,686 --> 00:20:44,853
And then nasty voice told:
265
00:20:47,016 --> 00:20:49,016
"Yes, sir, in the shit."
266
00:20:51,471 --> 00:20:53,769
But Venera had not sunk.
267
00:20:53,770 --> 00:20:56,323
The intense heat on the surface had melted
268
00:20:56,324 --> 00:20:58,741
the lens cap onto the camera.
269
00:21:00,573 --> 00:21:04,740
Three years later, another pair
of probes headed for Venus.
270
00:21:07,400 --> 00:21:09,675
This time, they took beautiful pictures
271
00:21:09,676 --> 00:21:12,960
of a patch of ground filled with lava.
272
00:21:12,961 --> 00:21:16,153
But when the probe tried to
sample the newzean rock,
273
00:21:16,154 --> 00:21:19,957
that lens cap came back to haunt them.
274
00:21:19,958 --> 00:21:24,180
Venera 14S, Venera 13,
they had special device
275
00:21:24,181 --> 00:21:25,910
to measure electric properties
276
00:21:25,911 --> 00:21:27,762
and mechanical properties of the surface.
277
00:21:27,763 --> 00:21:31,094
It's some arm, this arm
goes and puts device
278
00:21:31,095 --> 00:21:33,044
on the surface, it measures.
279
00:21:33,045 --> 00:21:36,086
And Venera 14 did it in a perfect way,
280
00:21:36,087 --> 00:21:38,087
but it just get the cap.
281
00:21:39,500 --> 00:21:42,042
So we measured mechanical properties
282
00:21:42,043 --> 00:21:45,420
and the electrical properties of that thing
283
00:21:45,421 --> 00:21:47,421
they brought from Earth.
284
00:21:57,635 --> 00:21:59,709
On the Planet's surface, the probes
285
00:21:59,710 --> 00:22:02,797
could only survive for
an hour or two at most.
286
00:22:02,798 --> 00:22:05,421
Somehow another way had to be found
287
00:22:05,422 --> 00:22:07,589
to see through the clouds.
288
00:22:20,550 --> 00:22:23,217
In 1989, NASA launched Magellan.
289
00:22:33,692 --> 00:22:36,617
Magellan wouldn't take pictures
but would scan the planet
290
00:22:36,618 --> 00:22:39,949
with radar to make out the
contours of the surface,
291
00:22:39,950 --> 00:22:44,117
cutting through the clouds
as if they weren't there.
292
00:22:45,093 --> 00:22:46,904
We were able to actually
come around the globe
293
00:22:46,905 --> 00:22:49,226
every day many times and build up a picture
294
00:22:49,227 --> 00:22:51,810
of the global geology of Venus.
295
00:22:57,574 --> 00:22:59,802
Magellan began to send back reams
296
00:22:59,803 --> 00:23:02,693
and reams of data, and
a whole new generation
297
00:23:02,694 --> 00:23:05,361
of geologists set to work on it.
298
00:23:08,453 --> 00:23:10,669
When the first image data
came back from Magellan,
299
00:23:10,670 --> 00:23:12,562
I went in about four in the morning,
300
00:23:12,563 --> 00:23:15,159
looked at the first strip of Magellan data,
301
00:23:15,160 --> 00:23:17,910
this first track down the Planet.
302
00:23:23,403 --> 00:23:26,162
To see the Planet's surface being revealed
303
00:23:26,163 --> 00:23:28,334
in such incredible detail and to say:
304
00:23:28,335 --> 00:23:30,760
"I'm one of the first
people who's ever looked
305
00:23:30,761 --> 00:23:33,512
"at this piece of ground on Venus."
306
00:23:33,513 --> 00:23:36,054
You felt like such an explorer.
307
00:23:36,055 --> 00:23:38,330
The first images showed that Venus had
308
00:23:38,331 --> 00:23:41,302
many similarities to Earth.
309
00:23:41,303 --> 00:23:43,183
There were large mountain ranges;
310
00:23:43,184 --> 00:23:45,853
some of them almost
similar to the Himalayas.
311
00:23:45,854 --> 00:23:48,605
There were long faults on
the Planet that looked
312
00:23:48,606 --> 00:23:51,403
maybe sort of similar to
faults we see on the Earth.
313
00:23:51,404 --> 00:23:53,841
There were volcanoes, lots
and lots of volcanoes
314
00:23:53,842 --> 00:23:55,559
on the surface, very large ones,
315
00:23:55,560 --> 00:23:56,906
much larger than some on the Earth,
316
00:23:56,907 --> 00:23:59,074
others on a similar scale.
317
00:24:05,324 --> 00:24:09,697
But then, an alien
landscape began to emerge.
318
00:24:09,698 --> 00:24:11,749
There were these huge circular features.
319
00:24:11,750 --> 00:24:15,371
And by huge, I mean about
250, 300 kilometers across.
320
00:24:15,372 --> 00:24:18,366
They were encircled by
ridges and they were high,
321
00:24:18,367 --> 00:24:20,595
they were sort of mountainous,
and they tended to have
322
00:24:20,596 --> 00:24:22,534
volcanoes all over the surfaces of 'em,
323
00:24:22,535 --> 00:24:24,137
"What are these features?
324
00:24:24,138 --> 00:24:25,286
"How could they have formed?"
325
00:24:25,287 --> 00:24:27,045
We've never seen anything like them.
326
00:24:31,608 --> 00:24:34,893
The 3D images revealed giant blisters
327
00:24:34,894 --> 00:24:37,853
that had oozed lava from every crack.
328
00:24:37,854 --> 00:24:39,618
And the surface of Venus seemed
329
00:24:39,619 --> 00:24:42,242
to have channels running through it.
330
00:24:42,243 --> 00:24:44,100
They looked like long rivers going across
331
00:24:44,101 --> 00:24:45,446
the surface of the Planet.
332
00:24:45,447 --> 00:24:48,836
But we know with Venus'
incredibly-high surface temperatures
333
00:24:48,837 --> 00:24:50,973
there's no way that water could
have formed those channels
334
00:24:50,974 --> 00:24:53,481
so they had to have been formed by lava.
335
00:25:04,441 --> 00:25:07,319
There are other volcanic features
that look like pancakes;
336
00:25:07,320 --> 00:25:09,653
they have very steep
sides and very flat tops
337
00:25:09,654 --> 00:25:11,124
and it literally looks like somebody threw
338
00:25:11,125 --> 00:25:14,909
a bunch of pancakes out onto
the surface of the Planet.
339
00:25:14,910 --> 00:25:17,092
There were other kinds of
volcanoes that looked like
340
00:25:17,093 --> 00:25:19,843
little squashed bugs, like ticks.
341
00:25:21,001 --> 00:25:23,329
Everywhere you look you see
some sort of volcanic feature:
342
00:25:23,330 --> 00:25:25,999
a flow, a small volcano, a weird channel.
343
00:25:26,000 --> 00:25:28,391
It's just dominated by volcanism
and that's just something
344
00:25:28,392 --> 00:25:31,283
we weren't prepared for really at all.
345
00:25:35,323 --> 00:25:37,714
It's intriguing to look at this surface
346
00:25:37,715 --> 00:25:40,465
that you say: "It should
be so much like the Earth;
347
00:25:40,466 --> 00:25:42,474
"it's not; how did it get this way?"
348
00:25:42,475 --> 00:25:43,600
It's just a puzzle.
349
00:25:43,601 --> 00:25:47,394
And to me, that's what makes
Venus so interesting.
350
00:25:57,333 --> 00:26:00,710
But when had this volcanic surface formed?
351
00:26:00,711 --> 00:26:03,914
Geologists hoped that by
counting impact craters,
352
00:26:03,915 --> 00:26:06,271
they could find out.
353
00:26:06,272 --> 00:26:07,882
When we got the global picture together,
354
00:26:07,883 --> 00:26:09,844
we started counting craters
and looking for areas
355
00:26:09,845 --> 00:26:11,702
that had a high density
of craters and an area
356
00:26:11,703 --> 00:26:14,372
that would have low density,
indicating old and young ages.
357
00:26:14,373 --> 00:26:16,102
When we look at the Moon, we look at Mars,
358
00:26:16,103 --> 00:26:17,692
we look at Mercury, you
have areas where you say:
359
00:26:17,693 --> 00:26:19,585
"OK, this area has more
craters, it's older;
360
00:26:19,586 --> 00:26:21,431
"this area has fewer
craters, it's younger."
361
00:26:21,432 --> 00:26:23,439
But the amazing part was
it looked like the craters
362
00:26:23,440 --> 00:26:25,959
were almost randomly distributed
across the surface.
363
00:26:25,960 --> 00:26:27,642
And you say: "Wait a
minute, the whole Planet,
364
00:26:27,643 --> 00:26:28,742
"it can't be the same age."
365
00:26:28,743 --> 00:26:29,576
It's the size of the Earth.
366
00:26:29,577 --> 00:26:31,437
How could you have a planet
the size of the Earth
367
00:26:31,438 --> 00:26:33,527
where the entire surface
formed at the same time.
368
00:26:33,528 --> 00:26:36,028
It just didn't make any sense.
369
00:26:37,835 --> 00:26:40,307
So what possible theory could explain
370
00:26:40,308 --> 00:26:42,808
how Venus' surface was formed?
371
00:26:47,355 --> 00:26:49,174
Well, it was really mystifying
because nobody could
372
00:26:49,175 --> 00:26:51,319
really be sure, since we hadn't
seen anything like this,
373
00:26:51,320 --> 00:26:52,596
what was going on.
374
00:26:52,597 --> 00:26:54,639
One of the main ideas that
came out was the idea
375
00:26:54,640 --> 00:26:57,045
that Venus' may have actually
been catastrophically
376
00:26:57,046 --> 00:26:59,531
resurfaced just a few
hundred million years ago.
377
00:27:07,019 --> 00:27:09,398
The idea that Venus boiled over
378
00:27:09,399 --> 00:27:13,566
in a planetwide flood of lava
is still fiercely debated.
379
00:27:29,380 --> 00:27:32,351
But if it did, and has now cooled down,
380
00:27:32,352 --> 00:27:34,519
could it ever erupt again?
381
00:27:36,961 --> 00:27:38,736
The most exciting thing would be to find
382
00:27:38,737 --> 00:27:42,219
an erupting volcano on Venus
to say: "Here we have proof
383
00:27:42,220 --> 00:27:44,123
"Venus is still geologically active.
384
00:27:44,124 --> 00:27:46,741
"It really is the Planet
most like the Earth
385
00:27:46,742 --> 00:27:48,137
"and here's proof of it.
386
00:27:48,138 --> 00:27:49,415
"It's not a dead planet;
387
00:27:49,416 --> 00:27:51,342
"it's still alive; it's still active."
388
00:27:51,343 --> 00:27:53,443
And that's something that I would
389
00:27:53,444 --> 00:27:56,444
give a awful lot to be able to find.
390
00:28:00,039 --> 00:28:02,975
Magellan scans the Planet for four years,
391
00:28:02,976 --> 00:28:05,476
but found no fresh lava flows.
392
00:28:06,482 --> 00:28:08,536
Venus may well be alive,
393
00:28:08,537 --> 00:28:11,037
but there's no sign of it yet.
394
00:28:12,392 --> 00:28:15,038
Of course if you were in orbit
around Earth for a year,
395
00:28:15,039 --> 00:28:16,765
you might not see any
volcanic activity at all;
396
00:28:16,766 --> 00:28:19,226
so it's really hard to tell
whether it's actually going.
397
00:28:19,227 --> 00:28:20,793
It's like trying to find the smoking gun
398
00:28:20,794 --> 00:28:24,627
or the smoking volcano;
it's not easy to find.
399
00:28:25,807 --> 00:28:28,194
Despite the discoveries of Magellan,
400
00:28:28,195 --> 00:28:31,778
Venus remains a Planet shrouded in mystery.
401
00:28:36,589 --> 00:28:39,177
Was Earth the only place where geologists
402
00:28:39,178 --> 00:28:42,138
would find active volcanoes?
403
00:28:42,139 --> 00:28:44,972
It was beginning to look that way.
404
00:28:47,479 --> 00:28:50,578
The only other rocky planet is Mercury.
405
00:28:50,579 --> 00:28:54,363
But it's a small world,
barely bigger than our Moon,
406
00:28:54,364 --> 00:28:58,531
and its surface is just as
dead and full of craters.
407
00:29:00,422 --> 00:29:04,647
No geological activity has
ever been found on Mercury.
408
00:29:04,648 --> 00:29:07,328
The outside of the Planet is baking hot;
409
00:29:07,329 --> 00:29:09,746
but inside, it is stone cold.
410
00:29:28,657 --> 00:29:31,254
There was no hope of finding
anything on Jupiter
411
00:29:31,255 --> 00:29:33,308
or the other giant planets
412
00:29:33,309 --> 00:29:36,226
because they have no solid surface.
413
00:29:37,210 --> 00:29:40,205
But there is some solid rock out here.
414
00:29:40,206 --> 00:29:44,373
On its way past Jupiter, Voyager
flew by the Planet's moons.
415
00:29:45,976 --> 00:29:48,645
No one expected to see much going on at all
416
00:29:48,646 --> 00:29:50,396
in these tiny worlds.
417
00:29:51,348 --> 00:29:55,260
We expected small objects the
size of the Moon or smaller
418
00:29:55,261 --> 00:29:57,350
to be pretty lifeless geologically
419
00:29:57,351 --> 00:29:59,268
and expected them to be
420
00:30:00,961 --> 00:30:03,674
holding records of the
very early Solar System.
421
00:30:03,675 --> 00:30:07,842
The impact processes and fairly
esoteric kinds of questions
422
00:30:09,318 --> 00:30:12,567
that solar system geologists
might be interested in
423
00:30:12,568 --> 00:30:14,367
but not something the general public
424
00:30:14,368 --> 00:30:16,785
would care a whole lot about.
425
00:30:19,209 --> 00:30:22,250
The first thing we ran
into course was Callisto
426
00:30:22,251 --> 00:30:25,745
and that was pretty much
what we had thought
427
00:30:25,746 --> 00:30:29,019
one of these moons would look like.
428
00:30:29,020 --> 00:30:31,573
Callisto is dark and icy.
429
00:30:31,574 --> 00:30:34,742
Like Mercury, its cratered
surface hasn't changed
430
00:30:34,743 --> 00:30:36,576
for billions of years.
431
00:30:40,061 --> 00:30:44,506
The next moon, Ganymede, is the
largest in the Solar System.
432
00:30:44,507 --> 00:30:46,674
It had little of interest.
433
00:30:56,164 --> 00:30:58,554
As Voyager reached the Moon lo,
434
00:30:58,555 --> 00:31:02,722
it was about to discover
something completely unexpected.
435
00:31:10,665 --> 00:31:13,880
As we looked at it from great distance
436
00:31:13,881 --> 00:31:17,943
we saw a lot of dark spots on the surface,
437
00:31:17,944 --> 00:31:20,904
which we thought maybe were
gonna be impact craters.
438
00:31:20,905 --> 00:31:25,048
But Voyager took a few
pictures and sailed past lo.
439
00:31:25,049 --> 00:31:28,624
The scientists wanted to focus on Jupiter.
440
00:31:28,625 --> 00:31:31,469
Meanwhile, one of the
engineers busied herself
441
00:31:31,470 --> 00:31:34,870
with some routine spacecraft maintenance.
442
00:31:34,871 --> 00:31:36,891
I came in about nine o'clock that morning
443
00:31:36,892 --> 00:31:40,362
to the navigation area and
the tape with the pictures
444
00:31:40,363 --> 00:31:44,054
the spacecraft had taken the
day before was on my desk.
445
00:31:44,055 --> 00:31:47,177
I put them on the computer
system and I displayed them.
446
00:31:47,178 --> 00:31:50,915
And I could see that the
Moon of lo was a crescent,
447
00:31:50,916 --> 00:31:54,491
as very often our own Moon is
a crescent in the night sky.
448
00:31:54,492 --> 00:31:57,614
I went and enhanced the
brightness and there appeared
449
00:31:57,615 --> 00:32:00,935
beside lo an object, a huge object
450
00:32:00,936 --> 00:32:03,895
that looked like something
I couldn't recognize
451
00:32:03,896 --> 00:32:05,916
and could never have expected
452
00:32:05,917 --> 00:32:09,250
and it completely captured my attention.
453
00:32:10,677 --> 00:32:12,986
I wanted to know so badly what that was
454
00:32:12,987 --> 00:32:14,542
that I just had to ask myself:
455
00:32:14,543 --> 00:32:16,190
"My goodness, what is that?"
456
00:32:16,191 --> 00:32:18,501
And the answer that occurred to me first
457
00:32:18,502 --> 00:32:22,791
was it looked like another
moon peaking out behind lo.
458
00:32:24,811 --> 00:32:27,033
But there was no other moon,
459
00:32:27,034 --> 00:32:29,492
and no fault in the camera.
460
00:32:29,493 --> 00:32:33,660
Linda Hyder decided that this
object had to be part of lo.
461
00:32:34,845 --> 00:32:38,129
And in fact that was very hard to accept
462
00:32:38,130 --> 00:32:41,090
because the size of this
object was enormous
463
00:32:41,091 --> 00:32:43,674
with respect to the size of lo.
464
00:32:53,572 --> 00:32:56,334
And when I explored it I was able to find
465
00:32:56,335 --> 00:32:58,842
that this large strange object,
466
00:32:58,843 --> 00:33:00,458
it was exactly coincident
467
00:33:00,459 --> 00:33:03,604
and fell over a heart-shaped feature on lo.
468
00:33:03,605 --> 00:33:06,762
What I had discovered was the huge plume
469
00:33:06,763 --> 00:33:10,756
of a volcanic eruption
arising 270 kilometers
470
00:33:10,757 --> 00:33:14,924
over the surface of lo and
raining back down onto it.
471
00:33:17,096 --> 00:33:20,508
So I had discovered the
first-ever volcanic eruption
472
00:33:20,509 --> 00:33:24,259
ever seen on another
world besides the Earth.
473
00:33:35,633 --> 00:33:40,606
We didn't really expect to
find active volcanic eruptions
474
00:33:40,607 --> 00:33:43,458
throwing material from a volcanic vent
475
00:33:43,459 --> 00:33:46,755
to an altitude of a couple hundred miles,
476
00:33:46,756 --> 00:33:49,149
300 kilometers above the surface.
477
00:33:49,150 --> 00:33:52,899
This stuff goes up with a
velocity of a high-powered rifle,
478
00:33:52,900 --> 00:33:55,163
and of course it comes
back onto the surface
479
00:33:55,164 --> 00:33:59,319
with the same velocity, so
a healthy place to stand
480
00:33:59,320 --> 00:34:01,903
would not be the surface of lo.
481
00:34:03,616 --> 00:34:07,690
The entire surface of lo
is covered with volcanoes,
482
00:34:07,691 --> 00:34:11,108
so volcanoes are not unique to our Earth.
483
00:34:17,963 --> 00:34:20,760
But why is lo volcanically active?
484
00:34:20,761 --> 00:34:22,873
It's only the size of our Moon.
485
00:34:22,874 --> 00:34:24,957
It should be cold inside.
486
00:34:27,205 --> 00:34:30,199
Head of the Voyager camera
team was Brad Smith.
487
00:34:30,200 --> 00:34:33,984
Up to this point, he'd concentrated
on Jupiter's atmosphere.
488
00:34:33,985 --> 00:34:36,068
Now he took a look at lo.
489
00:34:37,178 --> 00:34:38,950
Io is a very small body.
490
00:34:38,951 --> 00:34:42,572
It doesn't have enough of
the radioactive materials
491
00:34:42,573 --> 00:34:45,364
that heat up the rock,
as happens on the Earth,
492
00:34:45,365 --> 00:34:49,532
and so we didn't expect any
kind of volcanism on lo.
493
00:34:53,245 --> 00:34:57,445
The explanation was to be
found in our own Moon.
494
00:35:05,015 --> 00:35:09,182
And a NASA scientist in
California had predicted it.
495
00:35:11,772 --> 00:35:14,812
Well, as you can see, the
power of the Moon's gravity
496
00:35:14,813 --> 00:35:16,902
can move oceans on the Earth.
497
00:35:16,903 --> 00:35:20,176
Imagine what the power of Jupiter,
498
00:35:20,177 --> 00:35:22,963
which is 300 times the mass of the Earth,
499
00:35:22,964 --> 00:35:24,936
can have on lo.
500
00:35:24,937 --> 00:35:27,514
Now, lo, as it circles Jupiter,
501
00:35:27,515 --> 00:35:31,484
approaches Jupiter closer at
one point than at another.
502
00:35:31,485 --> 00:35:35,432
What this does is it changes
the gravitational force
503
00:35:35,433 --> 00:35:39,539
from Jupiter and results
in a giant squeeze.
504
00:35:39,540 --> 00:35:42,032
Physicist Ray Reynolds had realized
505
00:35:42,033 --> 00:35:44,830
that Jupiter's huge gravitational force
506
00:35:44,831 --> 00:35:47,082
was causing the interior of lo
507
00:35:47,083 --> 00:35:50,250
to heat up to incredible temperatures.
508
00:35:51,948 --> 00:35:54,489
We plugged in the numbers
into our equations
509
00:35:54,490 --> 00:35:57,763
and lo and behold, we
come out with thousands
510
00:35:57,764 --> 00:36:00,967
of degrees near the surface
of this satellite.
511
00:36:00,968 --> 00:36:02,895
Well, this immediately raised visions
512
00:36:02,896 --> 00:36:05,813
in our mind of volcanoes going off.
513
00:36:07,656 --> 00:36:10,116
But nobody could have
predicted the ferocity
514
00:36:10,117 --> 00:36:14,284
of the sulfur-spewing
volcanoes that Voyager found.
515
00:36:23,674 --> 00:36:27,818
Io is just enormously volcanically active,
516
00:36:27,819 --> 00:36:29,966
and more active than the Earth
517
00:36:29,967 --> 00:36:32,250
and any other body in the Solar System.
518
00:36:32,251 --> 00:36:34,209
There's nothing that
even comes close to it.
519
00:36:34,210 --> 00:36:38,377
Its surface is completely
covered with volcanic debris.
520
00:36:42,305 --> 00:36:44,893
Finally, geologists had found a world
521
00:36:44,894 --> 00:36:48,144
that was alive yet constantly changing.
522
00:36:49,770 --> 00:36:53,937
Draw a map of lo, and it will
be obsolete by the next day.
523
00:36:59,371 --> 00:37:03,062
But lo wasn't the only
surprise Voyager found.
524
00:37:03,063 --> 00:37:05,814
Next to it lay the Jupiter Moon Europa,
525
00:37:05,815 --> 00:37:07,815
a bright dazzling world.
526
00:37:12,630 --> 00:37:15,590
Europa was surprisingly smooth;
527
00:37:15,591 --> 00:37:19,154
that is, there was little or
no topography on it at all.
528
00:37:19,155 --> 00:37:22,161
Scaled down it would have been
as smooth as a billiard ball.
529
00:37:22,162 --> 00:37:26,480
And why it should be, why
there was no topography
530
00:37:26,481 --> 00:37:28,279
we could only guess.
531
00:37:28,280 --> 00:37:32,598
Close up, scientists were
baffled by its surface.
532
00:37:32,599 --> 00:37:34,398
When we looked at Europa, we see
533
00:37:34,399 --> 00:37:38,508
a startling lack of craters and we also see
534
00:37:38,509 --> 00:37:40,725
that there are large linear features
535
00:37:40,726 --> 00:37:43,809
that look like cracks on the surface.
536
00:37:48,075 --> 00:37:50,048
Reynolds thought the cracks might be
537
00:37:50,049 --> 00:37:51,801
a result of the constant pressure
538
00:37:51,802 --> 00:37:55,135
from Jupiter's huge gravitational force.
539
00:37:58,373 --> 00:38:01,298
And there was an intriguing possibility.
540
00:38:01,299 --> 00:38:04,375
Europa's surface is made of ice.
541
00:38:04,376 --> 00:38:08,322
Could that mean that there
might be water beneath?
542
00:38:08,323 --> 00:38:10,621
Our calculations indicated that there was
543
00:38:10,622 --> 00:38:13,291
a good possibility that there could be
544
00:38:13,292 --> 00:38:16,042
a ocean beneath a thin ice layer.
545
00:38:19,260 --> 00:38:21,337
Voyager's images were too crude
546
00:38:21,338 --> 00:38:26,259
to prove or disprove the idea
of a subterranean ocean.
547
00:38:26,260 --> 00:38:30,091
But 16 years later, another
spacecraft, Galileo,
548
00:38:30,092 --> 00:38:32,342
returned for a closer look.
549
00:38:34,898 --> 00:38:37,359
Close up, Europa's surface looks
550
00:38:37,360 --> 00:38:39,878
like a crazy paving of ice.
551
00:38:39,879 --> 00:38:42,374
There are giant icebergs.
552
00:38:42,375 --> 00:38:44,673
It seems that hot water has welled up
553
00:38:44,674 --> 00:38:47,099
through a network of cracks from below
554
00:38:47,100 --> 00:38:49,804
and then frozen instantly in place,
555
00:38:49,805 --> 00:38:53,888
just like lava from a
volcanic eruption on Earth.
556
00:38:57,375 --> 00:38:59,383
Instead of hot rock that's coming out,
557
00:38:59,384 --> 00:39:01,147
it's water, it's liquid water.
558
00:39:01,148 --> 00:39:03,353
But the principle is the same.
559
00:39:03,354 --> 00:39:06,175
There's a fluid down underneath the crust
560
00:39:06,176 --> 00:39:09,054
and from time to time
this pushes up and flows
561
00:39:09,055 --> 00:39:11,306
onto the surface much in the same way
562
00:39:11,307 --> 00:39:15,474
that hot lava flows onto
the surface of the Earth.
563
00:39:25,088 --> 00:39:28,501
No actual eruption of ice
has yet been spotted
564
00:39:28,502 --> 00:39:30,927
but Europa has opened up the possibility
565
00:39:30,928 --> 00:39:34,678
of completely new kinds
of geological worlds.
566
00:40:02,170 --> 00:40:04,967
As space probes ventured further out,
567
00:40:04,968 --> 00:40:07,551
they found other frozen worlds.
568
00:40:20,363 --> 00:40:23,033
Among the moons of Saturn and Uranus
569
00:40:23,034 --> 00:40:26,867
there were signs of strange
geological events.
570
00:40:30,209 --> 00:40:34,376
But it all seemed to have
occurred millions of years ago.
571
00:40:41,142 --> 00:40:44,682
Then, a decade after its
encounter with Jupiter,
572
00:40:44,683 --> 00:40:47,683
Voyager met Triton, Moon of Neptune.
573
00:40:52,253 --> 00:40:54,713
Triton, as we got closer and closer,
574
00:40:54,714 --> 00:40:59,020
became evident that it was
gonna be a very tiny object
575
00:40:59,021 --> 00:41:02,152
and that was covered with
very very bright material.
576
00:41:02,153 --> 00:41:04,161
That made it very cold,
577
00:41:04,162 --> 00:41:06,332
the coldest thing we've encountered
578
00:41:06,333 --> 00:41:09,250
so far throughout the Solar System.
579
00:41:10,327 --> 00:41:12,531
Triton is so cold that even
580
00:41:12,532 --> 00:41:15,283
its thin atmosphere of nitrogen freezes
581
00:41:15,284 --> 00:41:18,685
into a solid icecap every winter.
582
00:41:18,686 --> 00:41:23,085
To have expected geologic
activity on such a surface
583
00:41:23,086 --> 00:41:25,169
would be insane, frankly.
584
00:41:28,798 --> 00:41:30,887
But when Voyager got close,
585
00:41:30,888 --> 00:41:35,055
it saw there were dark streaks
all over the fresh icecap.
586
00:41:38,794 --> 00:41:41,847
Those dark markings had to be
sitting on top of that ice.
587
00:41:41,848 --> 00:41:44,819
They had to be laid down
there in the recent past.
588
00:41:44,820 --> 00:41:48,429
That meant something had to
be going on to make them,
589
00:41:48,430 --> 00:41:49,930
an active process.
590
00:41:52,993 --> 00:41:54,966
Larry Sodablom spent two months
591
00:41:54,967 --> 00:41:57,392
looking at pictures of Triton.
592
00:41:57,393 --> 00:42:00,280
He examined images taken from
slightly different angles
593
00:42:00,281 --> 00:42:03,810
to try and build up a
3D view of the surface.
594
00:42:03,811 --> 00:42:05,818
All of a sudden, he saw something
595
00:42:05,819 --> 00:42:09,707
that seemed to stand up from the ice.
596
00:42:09,708 --> 00:42:12,958
One afternoon we were stunned to find
597
00:42:14,852 --> 00:42:19,019
active geysers shooting up
above the Triton icecap.
598
00:42:21,179 --> 00:42:25,938
Geysers, fountains of material
rising five, 10 kilometers
599
00:42:25,939 --> 00:42:28,189
or miles above the surface.
600
00:42:47,093 --> 00:42:50,249
Even in this dark corner
of the Solar System,
601
00:42:50,250 --> 00:42:52,467
the faint heat of the Sun manages
602
00:42:52,468 --> 00:42:54,885
to penetrate Triton's icecap.
603
00:43:03,241 --> 00:43:06,642
It warms liquid nitrogen
trapped beneath the surface
604
00:43:06,643 --> 00:43:10,334
up to the point where it bursts
out and rises up into space
605
00:43:10,335 --> 00:43:14,502
before turning 90 degrees into
Triton's high-altitude winds.
606
00:43:19,228 --> 00:43:22,583
It's almost as if Triton
was the last sentence
607
00:43:22,584 --> 00:43:26,402
in the message that we got
from the Voyager Mission,
608
00:43:26,403 --> 00:43:28,666
that no matter where you
go in the universe,
609
00:43:28,667 --> 00:43:30,667
expect the unexpectable.
610
00:43:37,293 --> 00:43:39,716
Changed that whole concept
of what volcanism is.
611
00:43:39,717 --> 00:43:42,723
Our classical concept of
course before Voyager
612
00:43:42,724 --> 00:43:44,975
was volcanism was hot rock coming out
613
00:43:44,976 --> 00:43:47,193
of the interior of a planet.
614
00:43:47,194 --> 00:43:50,374
But Voyager showed us that
there are other materials
615
00:43:50,375 --> 00:43:53,334
as well that produce volcanism.
616
00:43:53,335 --> 00:43:56,918
On lo we saw molten sulfur, sulfur dioxide.
617
00:43:58,466 --> 00:44:01,883
On Europa, water is an important element.
618
00:44:03,038 --> 00:44:06,776
And on Triton, liquid
nitrogen may actually be
619
00:44:06,777 --> 00:44:10,027
the fluid that's involved in volcanism.
620
00:44:12,036 --> 00:44:14,369
After so many amazing discoveries
621
00:44:14,370 --> 00:44:18,061
across the Solar System,
geologists are now returning
622
00:44:18,062 --> 00:44:20,979
to the Earth's neighboring planets.
623
00:44:25,550 --> 00:44:28,050
In 1997, NASA returned to Mars
624
00:44:29,008 --> 00:44:31,844
with a new orbiting
spacecraft that's providing
625
00:44:31,845 --> 00:44:34,512
greater detail than ever before.
626
00:44:40,309 --> 00:44:43,512
Mars Global Surveyor can
pick out individual boulders
627
00:44:43,513 --> 00:44:45,602
on the ground and can spot places where
628
00:44:45,603 --> 00:44:48,353
they've rolled down into gullies.
629
00:44:49,341 --> 00:44:52,258
Could these be evidence of tremors?
630
00:44:55,007 --> 00:44:57,386
And a new probe, Mars Express,
631
00:44:57,387 --> 00:45:01,795
has now discovered evidence
of methane on the Red Planet.
632
00:45:01,796 --> 00:45:05,963
Could all this point to
geological activity on Mars?
633
00:45:07,189 --> 00:45:10,754
What we're seeing now
on Mars is like a shot
634
00:45:10,755 --> 00:45:14,748
from a helicopter compared to
a shot from a space shuttle.
635
00:45:14,749 --> 00:45:19,102
The whole sense of Mars
is a little bit different
636
00:45:19,103 --> 00:45:22,605
when you get down to the size
of detail that we can see.
637
00:45:22,606 --> 00:45:24,576
And we're just beginning to get into that
638
00:45:24,577 --> 00:45:27,943
and get a sense of what's
really going on on Mars.
639
00:45:27,944 --> 00:45:30,253
Soon we will have a map of Mars
640
00:45:30,254 --> 00:45:33,671
that's as detailed as those of the Earth.
641
00:45:43,048 --> 00:45:44,925
Now when I come out to Hawaii,
642
00:45:44,926 --> 00:45:47,769
my whole perspective has changed.
643
00:45:47,770 --> 00:45:49,581
I walk around on the surface here,
644
00:45:49,582 --> 00:45:51,020
and in fact I'm beginning to see things
645
00:45:51,021 --> 00:45:52,948
that are the same scale
that I'm seeing on Mars
646
00:45:52,949 --> 00:45:54,747
and it's incredibly exciting.
647
00:45:54,748 --> 00:45:56,930
It's bridged the gap;
it's brought it together
648
00:45:56,931 --> 00:46:00,479
so it's almost like I'm
walking around on Mars.
649
00:46:00,480 --> 00:46:02,372
I think this is the way it's
worked with all the planets.
650
00:46:02,373 --> 00:46:04,218
They initially were alien objects
651
00:46:04,219 --> 00:46:06,354
that you had little knowledge about.
652
00:46:06,355 --> 00:46:08,374
But particularly from the
geology you begin to see
653
00:46:08,375 --> 00:46:10,580
old friends: volcanoes and lava flows,
654
00:46:10,581 --> 00:46:12,194
sand dunes and so on.
655
00:46:12,195 --> 00:46:15,305
And then little by little you
transport yourself there,
656
00:46:15,306 --> 00:46:16,174
you think about there.
657
00:46:16,175 --> 00:46:18,945
I wake up in the night, I have
a dream about being on Mars.
658
00:46:18,946 --> 00:46:20,292
It's just amazing.
659
00:46:29,868 --> 00:46:33,849
One day soon, a probe may
also return to Venus
660
00:46:33,850 --> 00:46:36,426
and perhaps survive for
long enough in its hostile
661
00:46:36,427 --> 00:46:39,844
atmosphere to observe a volcano erupting.
662
00:46:52,951 --> 00:46:56,056
We now know that the Earth is just one
663
00:46:56,057 --> 00:46:58,974
in a Solar System of active worlds.
664
00:47:03,127 --> 00:47:05,960
Every year brings new discoveries.
665
00:47:15,329 --> 00:47:17,464
The Galileo Probe was one of the most
666
00:47:17,465 --> 00:47:20,216
ambitious projects so far.
667
00:47:20,217 --> 00:47:24,988
It gave us a unique insight into
Io, one of Jupiter's moons.
668
00:47:24,989 --> 00:47:28,471
We now know it is the most
volcanically-active world
669
00:47:28,472 --> 00:47:30,139
in the Solar System.
670
00:47:54,362 --> 00:47:57,356
But the Galileo is no more.
671
00:47:57,357 --> 00:48:01,211
With its fuel spent and suffering
critical radiation damage,
672
00:48:01,212 --> 00:48:05,295
it dived headlong into
Jupiter's vast atmosphere.
673
00:48:06,390 --> 00:48:09,223
It was the end for the spacecraft;
674
00:48:11,359 --> 00:48:15,720
but this is just the start of
our new voyage of discovery
675
00:48:15,721 --> 00:48:17,554
into the Solar System.
54164
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