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NARRATOR:
Our planet: Earth.

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You may think you know it well.

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But a startling new picture
is emerging

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of a world shaped by forces

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more dynamic and intertwined
than we ever imagined,

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raising possibilities
that defy common sense.

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How can sandstorms
in the Sahara Desert

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transform the Amazon rainforest
over 5,000 miles away?

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In the frigid ocean
beneath Antarctica,

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how can a vast
undersea waterfall

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500 times bigger
than Niagara Falls

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lead to a gigantic
feeding frenzy near the equator?

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And how can warm water streaming
past the coast of Africa

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trigger a weather catastrophe

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half a world away
in the southern United States?

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Scientists have begun to find
surprising answers

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to these and other
profound questions

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thanks to a network
of satellites

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orbiting high above the earth.

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Ever watchful,

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their senses extend far beyond
what our eyes can see.

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EMILY SHUCKBURGH:
It's really the last bastion of human discovery.

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We're discovering new things
every day.

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NARRATOR:
What are these hidden forces that rule our world?

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How are the oceans,
the continents, the atmosphere

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and even the sun
bound together,

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and how do they affect
all living things?

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For the first time,
we can understand

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how earth, fire, wind and water
join together

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to create the dynamic
environments

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that shape life
in all its forms.

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WALEED ABDALATI:
Their interaction

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is what has created
the environment, the diversity,

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the kind of life
we see on earth today.

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NARRATOR:
With astonishing images

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created from a wealth of new
information from satellites,

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this is our planet
as never seen before.

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"Earth from Space,"
right now on <i>NOVA.</i>

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Major funding for <i>NOVA</i> is
provided by the following:

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Supporting <i>NOVA</i> and promoting
public understanding of science.

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And the Corporation
for Public Broadcasting,

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and by:

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And Millicent Bell, through:

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Major funding for "Earth
from Space" is provided by:

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Furthering the values that
contribute to a healthy planet.

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NARRATOR:
Since humans first ventured into space,

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some of the greatest gifts
of exploration

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have been the new views
of our home.

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Who can forget the iconic
"earthrise" images

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of the Apollo era?

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And now from the International
Space Station,

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we have these spectacular
vistas.

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The blue marble is finally
revealing its secrets.

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It's a planet alive with
activity and constant change,

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its ace transformed
by humans

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yet still ruled by powerful
natural forces

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that we are only beginning
to understand.

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ABDALATI:
It's just spectacular when you view it from space.

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It's teeming with diversity,
with beauty.

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Amazing colors, you know,

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the blues and the greens
and the whites.

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PIERS SELLERS:
You see the world

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as one huge system

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all linked through
the atmosphere and the oceans,

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rolling its way
around the sun.

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NARRATOR:
So what is it that shapes Earth's dynamic face?

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What are the essential
ingredients,

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and how do they combine to
generate and sustain all life?

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How do the natural forces
that surround us work together

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to create an engine
powerful enough

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to nourish and drive life
forward in all its diversity?

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Our best hope for answers
may come from above.

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Orbiting over our heads
are 120 satellites

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keeping watch from space.

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Most operate at altitudes

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ranging from a few hundred miles
above the surface of the planet

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to as high as 25,000 miles.

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Each one of these
Earth-observing satellites

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reveals a different piece
of the puzzle.

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Each carries an array of
exquisitely sensitive detectors,

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designed to reveal
what would otherwise

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be hidden fr our view.

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The satellites are
absolutely amazing

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because not only can we see
visible things from space,

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but also we can see things that
aren't visible to the human eye.

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So satellites are enabling us

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to turn what are
invisible processes

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into visible things we can see
and then understand.

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NARRATOR:
To see how our world works, in this program

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we have taken information
provided by satellites,

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combined it with
computer models,

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and rendered the results

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in these scientifically
accurate graphics.

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With the invisible
now revealed,

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we can see Earth as
an endlessly changing system.

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These images will show
in great detail

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how sunlight, moisture,
land and atmosphere interact

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in unexpected ways,

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with seemingly local events

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often triggered by forces
far away in space and time.

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And with these new insights,
for the first time,

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scientists can begin
to understand

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the intimate relationship
between the planet

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and all the living things
it supports.

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ABDALATI:
It's really the thrill,

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because it matters so much,

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of piecing together the story
of what the earth is doing,

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how it's changing,
why it's changing

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and how ultimately
that affects humans.

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NARRATOR:
The first piece of the puzzle

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is in understanding
the massive influence the sun,

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from 93 million miles away,
has on our planet.

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The world's continuously bathed

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in a flow of energy
from the sun.

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That warms the earth.

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Everything that you can see
that lives and breathes

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and moves on the earth
is pushed by the sun.

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NARRATOR:
Now an electronic eye in space

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can measure the impact
of the sun's energy

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all around the earth.

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One of NASA's newest satellites,

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named for a meteorologist,
polar-orbiting <i>Suomi,</i>

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launched in 2011,
provides the view.

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The spacecraft is the size
of a small school bus.

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It orbits 500 miles up, circling
the planet 14 times a day.

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On board, it carries
five separate sensors

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that enable it to see things
invisible to human eyes.

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The light that we can see

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is confined to a narrow band
of electromagnetic radiation,

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just a tiny portion of what
the satellite can pick up.

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Electromagnetic radiation
spans a spectrum

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that goes far beyond the
familiar colors of the rainbow.

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ABDALATI:
If you were to consider the full spectrum to be a line

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that stretched from New York
City to Los Angeles,

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the piece that our eyes
could see

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would be about
the size of a dime.

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There is so much other
information out there

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available to us,

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and that's in large part
what these satellites do.

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NARRATOR:
One of this satellite's key instruments is called CERES,

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an acronym for Clouds and
Earth's Radiant Energy System.

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It detects a broad range
of the spectrum,

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including the very short and
very long wavelengths of light

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in the ultraviolet and infrared
that we can't see.

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This is a CERES-eye view
of the planet.

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Anything that emits heat
gives off infrared radiation,

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so the CERES data shows
the earth in shades of heat,

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accurate to a fraction
of a degree.

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It reveals how the planet
as a whole reacts to sunlight,

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both absorbing and reflecting
the radiation

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coming from our local star.

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At the poles, the sun strikes
at an oblique angle,

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and what little light there is

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gets reflected back out to space
by the ice and clouds.

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These are the primary reasons
why the poles remain cool.

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At the equator,
it's a very different story.

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Not only does the planet receive
more direct sunlight here,

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the lack of ice means that

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less of the sun's energy
is reflected back into space.

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And at the equator,

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the sun's concentrated energy
fuels a heat engine

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that can trigger weather events
around the world.

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Perhaps the best place to see
the impact of the sun's heat

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is an area in the Atlantic

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just north of the equator
and west of Africa:

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the coastal waters
of the Cape Verde islands.

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Here, the sea provides a living.

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The local fishermen keep
a careful eye on the weather.

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They know that storms
can bring a good catch.

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Turbulent weather stirs up
nutrients from the deep,

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attracting great shoals of fish.

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It's the hottest time
of the year,

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and the sun beats down
relentlessly.

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By late afternoon,
the huge inflow of heat energy

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has led to the buildup
of large cloud formations.

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Sometimes, these formations
develop into massive storms.

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It's a process that satellites
are revealing in fine detail.

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Circling above the fishermen is
a NASA satellite called <i>Aqua--</i>

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Latin for "water."

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It orbits the poles.

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One of its key tasks is to
monitor the complex interaction

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between sunlight and water.

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JEFFREY HALVERSON:
<i>Aqua</i> satellite is one of NASA's flagship satellites.

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Its primary function is to study
the hydrologic cycle on Earth:

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vapor in the atmosphere,
liquid ocean,

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the temperature of that ocean
and the ice.

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NARRATOR:
One of <i>Aqua's</i> instruments

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looks down at the sea
around Cape Verde,

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again in infrared,
sensing heat.

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Highlighted here in yellow,

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over one million
square miles of ocean

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reaches a critical temperature:
80 degrees.

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At this temperature,
the sea is evaporating fast,

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producing an invisible gas:
water vapor.

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SHUCKBURGH:
By looking at the infrared, the <i>Aqua</i> satellite

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is able to measure the amount
of water vapor evaporating

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from the surface of the ocean.

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NARRATOR:
<i>Aqua</i> shows that this area

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is producing millions of tons
of water vapor every hour.

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Based on that data,
it's possible to create an image

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of what the vapor
might look like

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if these fishermen
could actually see it

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in the air around them.

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Water vapor is much lighter
than air,

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and vast columns rise upward,

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directly from the surface
of the sea.

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The water vapor carries with it
heat, the energy of the sun.

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HALVERSON:
Well, water vapor is like invisible energy.

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It's like molecules
escaping the ocean,

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taking heat energy with them,

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and they're like little
mobile solar collectors

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that are zipping
around the atmosphere.

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NARRATOR:
Half a mile up, as the air cools,

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the water vapor condenses
back into liquid water--

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tiny droplets
that form vast clouds.

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The vapor releases
the sun's energy,

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the heat it received earlier.

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The result is a storm.

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HALVERSON:
Molecules condense in the atmosphere

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and become liquid again,

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and when that happens,

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that heat is given off
into the atmosphere

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and it warms the atmosphere,

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and that's the heat
that powers storm systems.

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NARRATOR:
In the worst storms, the heat captured by the water vapor

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is equivalent to up to 200 times

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the global production of
electricity at any given moment.

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The process of evaporation
results in something

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we don't need special
instruments to see.

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The rising heat drives
the clouds up to ten miles high.

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As the clouds rise upward,

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the earth's rotation
causes them to spin.

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The thunderclouds merge
into a vast vortex.

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This is the birth
of a hurricane.

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(loud winds blowing)

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It is 2005, the busiest
hurricane season on record.

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On August 27,
a meteorological satellite

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is tracking
a category three hurricane

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that started in the Bahamas.

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Its name is Hurricane Katrina.

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Throughout the region,

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there is one question
on everyone's mind:

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will the hurricane hit land,
or will it blow itself out?

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The answer may come from
a NASA satellite called <i>TRMM,</i>

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the Tropical Rainfall
Measuring Mission.

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00:16:51,577 --> 00:16:55,314
<i>TRMM</i> is equipped with a radar
and imager

247
00:16:55,347 --> 00:16:58,183
that operate in the microwave
range of the spectrum.

248
00:16:58,217 --> 00:17:00,386
These are higher in energy

249
00:17:00,419 --> 00:17:04,223
and shorter in wavelength
than other radio waves.

250
00:17:06,625 --> 00:17:08,327
The instruments
bounce microwaves

251
00:17:08,360 --> 00:17:10,562
off raindrops in the clouds,

252
00:17:10,596 --> 00:17:14,266
allowing scientists to build
a three-dimensional model

253
00:17:14,299 --> 00:17:18,270
of the internal structure
of a hurricane.

254
00:17:20,372 --> 00:17:22,307
HALVERSON:
We can actually look at microwave energy

255
00:17:22,341 --> 00:17:25,110
which is generated
within the clouds

256
00:17:25,144 --> 00:17:27,346
and coming from
the ocean's surface.

257
00:17:27,379 --> 00:17:29,314
It's almost as if the clouds
are now invisible to us;

258
00:17:29,348 --> 00:17:31,884
we can see right through them
like taking a CAT scan

259
00:17:31,917 --> 00:17:33,118
to look inside those clouds.

260
00:17:33,152 --> 00:17:38,390
NARRATOR:
This satellite is a powerful tool,

261
00:17:38,424 --> 00:17:43,429
and now its sensors reveal
something ominous.

262
00:17:43,462 --> 00:17:47,066
Huge, vertical columns
of warm water vapor

263
00:17:47,099 --> 00:17:50,002
burst up from near the center
of the storm.

264
00:17:50,035 --> 00:17:53,439
Almost like hurricanes
within hurricanes,

265
00:17:53,472 --> 00:17:57,743
these climbing vortices deliver
added infusions of energy

266
00:17:57,776 --> 00:18:02,648
into the heart of the storm,
fueling its growth even more.

267
00:18:02,681 --> 00:18:07,486
These new sources of energy
are called hot towers.

268
00:18:07,519 --> 00:18:10,389
HALVERSON:
If they occur in the right place at the right time,

269
00:18:10,422 --> 00:18:12,024
near the very center
of the system,

270
00:18:12,057 --> 00:18:13,659
they can be like
a giant spark plug

271
00:18:13,692 --> 00:18:15,694
that gets that
whole engine running

272
00:18:15,727 --> 00:18:17,563
at very, very high speed.

273
00:18:22,234 --> 00:18:27,272
NARRATOR:
The hot towers draw more and more water vapor off the ocean.

274
00:18:27,306 --> 00:18:31,343
This triggers a feedback loop

275
00:18:31,376 --> 00:18:34,246
that leads to
a runaway reaction.

276
00:18:34,279 --> 00:18:36,081
In just 24 hours,

277
00:18:36,115 --> 00:18:40,686
Hurricane Katrina grows
into a category five monster.

278
00:18:48,560 --> 00:18:51,897
(loud winds blowing)

279
00:18:51,930 --> 00:18:53,632
(screaming)

280
00:18:53,665 --> 00:18:57,336
NARRATOR:
All this violence is a direct result

281
00:18:57,369 --> 00:18:59,304
of the power of the sun
on the ocean.

282
00:18:59,338 --> 00:19:03,709
Ferocious winds blow
for two days straight,

283
00:19:03,742 --> 00:19:09,781
reaching 175 miles an hour,

284
00:19:09,815 --> 00:19:11,817
twisting steel like paper

285
00:19:11,850 --> 00:19:14,786
and ripping apart homes
and buildings.

286
00:19:22,594 --> 00:19:24,763
Over three trillion gallons
of rain a day

287
00:19:24,796 --> 00:19:29,635
and a massive tidal surge
from the Gulf of Mexico

288
00:19:29,668 --> 00:19:34,373
combine to inundate whole areas
of the Gulf Coast.

289
00:19:44,883 --> 00:19:49,154
Katrina leaves its mark
across 90,000 square miles.

290
00:19:49,188 --> 00:19:53,959
Over a million people
are displaced.

291
00:19:53,992 --> 00:19:56,795
Katrina becomes the standard

292
00:19:56,828 --> 00:19:59,798
by which future hurricanes
will be assessed.

293
00:19:59,831 --> 00:20:02,768
But even this extreme hurricane

294
00:20:02,801 --> 00:20:07,005
is just a tiny brushstroke
in a much bigger picture:

295
00:20:07,039 --> 00:20:13,111
a picture of how the sun drives
water around the entire planet

296
00:20:13,145 --> 00:20:16,582
with radically different effects
in different places,

297
00:20:16,615 --> 00:20:21,620
all under the watchful gaze
of our eyes in space.

298
00:20:28,860 --> 00:20:30,696
Take just a single day in July.

299
00:20:30,729 --> 00:20:34,967
In New York, commuters swelter
in 95 degree heat.

300
00:20:35,000 --> 00:20:39,104
Searing winds pump hot air
into the region from the south,

301
00:20:39,137 --> 00:20:42,441
creating oppressive,
humid conditions.

302
00:20:42,474 --> 00:20:48,146
7,000 miles away,
in Mumbai, India,

303
00:20:48,180 --> 00:20:51,984
commuters here struggle
to cope with torrential rain.

304
00:20:55,454 --> 00:20:57,422
The deluge comes so fast

305
00:20:57,456 --> 00:20:59,625
that the streets
are flooded in hours.

306
00:21:03,028 --> 00:21:05,330
Meanwhile, in Chile,

307
00:21:05,364 --> 00:21:08,934
the desert of the Atacama
is almost totally dry.

308
00:21:12,304 --> 00:21:13,905
There are places here

309
00:21:13,939 --> 00:21:16,908
where rainfall
has never been recorded.

310
00:21:18,944 --> 00:21:23,949
Such diverse environments,
thousands of miles apart,

311
00:21:23,982 --> 00:21:26,752
appear totally unrelated.

312
00:21:26,785 --> 00:21:29,488
But by pulling back
for a wider view,

313
00:21:29,521 --> 00:21:33,725
we can see that they are in fact
intimately connected.

314
00:21:42,868 --> 00:21:45,470
Orbiting 22,000 miles
from Earth's surface

315
00:21:45,504 --> 00:21:49,941
is a chain of five
weather-tracking spacecraft,

316
00:21:49,975 --> 00:21:52,978
including this one:
NASA's <i>GOES East.</i>

317
00:21:56,682 --> 00:21:59,217
<i>GOES</i> is an acronym

318
00:21:59,251 --> 00:22:03,288
for Geostationary Operational
Environmental Satellite.

319
00:22:03,322 --> 00:22:07,459
Each moves in a fixed position
relative to the earth,

320
00:22:07,492 --> 00:22:09,995
called a geostationary orbit.

321
00:22:10,028 --> 00:22:13,298
They always look down
on the same parts of the planet.

322
00:22:13,332 --> 00:22:16,668
The combined data
from these five satellites

323
00:22:16,702 --> 00:22:20,372
gives scientists a unique
perspective on the earth.

324
00:22:20,405 --> 00:22:22,874
SHUCKBURGH:
By having several of them

325
00:22:22,908 --> 00:22:25,977
located at different positions
around the equator,

326
00:22:26,011 --> 00:22:28,714
we're able to get a view
of the whole earth

327
00:22:28,747 --> 00:22:30,382
24 hours a day.

328
00:22:33,685 --> 00:22:37,189
NARRATOR:
By observing the entire earth, these satellites reveal

329
00:22:37,222 --> 00:22:40,525
how energy moves
throughout the globe,

330
00:22:40,559 --> 00:22:44,763
beginning with the impact
of the sun on water.

331
00:22:44,796 --> 00:22:47,532
The process is the same
everywhere,

332
00:22:47,566 --> 00:22:53,071
but the outcome will be very
different in different places.

333
00:22:53,105 --> 00:22:56,208
Converted from
the numerical data,

334
00:22:56,241 --> 00:22:58,977
these five circles
graphically depict

335
00:22:59,010 --> 00:23:01,680
what the satellites
actually sense.

336
00:23:01,713 --> 00:23:05,250
They reveal the total picture
of water vapor produced on earth

337
00:23:05,283 --> 00:23:08,019
in a single frame.

338
00:23:13,592 --> 00:23:19,731
Seen here in fast forward,
one second is equal to a day.

339
00:23:19,765 --> 00:23:23,735
It shows how water vapor
produced at the equator

340
00:23:23,769 --> 00:23:28,774
continuously transports the
sun's energy towards the poles.

341
00:23:31,176 --> 00:23:34,746
Local landscapes and topography
affect the vapor's impact,

342
00:23:34,780 --> 00:23:38,850
with results unique
to each region.

343
00:23:47,192 --> 00:23:49,594
In India at the end of July,

344
00:23:49,628 --> 00:23:53,698
the warm water vapor is drawn
from over the ocean

345
00:23:53,732 --> 00:23:57,903
by the difference in temperature
between land and sea.

346
00:24:02,474 --> 00:24:05,177
Rising to high altitude,

347
00:24:05,210 --> 00:24:09,948
the vapor cools over the land
and condenses back into water.

348
00:24:09,981 --> 00:24:14,019
We call the result
the Asian Monsoon.

349
00:24:24,663 --> 00:24:29,000
Nearly a trillion tons of rain
falls out of the sky,

350
00:24:29,034 --> 00:24:32,704
transforming parched land
into fertile plains.

351
00:24:44,783 --> 00:24:49,154
The monsoon eventually moves
to the east, reaching China,

352
00:24:49,187 --> 00:24:53,124
where it floods the paddies
that are ideal for growing rice.

353
00:25:02,934 --> 00:25:08,540
This process helps provide food
for three billion people,

354
00:25:08,573 --> 00:25:10,742
almost half the world's
population.

355
00:25:17,949 --> 00:25:22,020
Meanwhile, on the other side
of the world in South America,

356
00:25:22,053 --> 00:25:24,155
westbound winds
drive water vapor

357
00:25:24,189 --> 00:25:27,759
across the high peaks
of the Andes.

358
00:25:27,792 --> 00:25:30,562
The altitude strips the air
of its moisture,

359
00:25:30,595 --> 00:25:33,765
which falls as snow
on the mountains,

360
00:25:33,798 --> 00:25:36,768
creating on the far side
in central Chile

361
00:25:36,801 --> 00:25:39,070
the arid desert of the Atacama.

362
00:25:50,849 --> 00:25:54,619
That same July day
in the eastern United States,

363
00:25:54,653 --> 00:25:57,255
hot, moist air surges north

364
00:25:57,289 --> 00:26:01,326
straight from
the Gulf of Mexico.

365
00:26:01,359 --> 00:26:03,194
With no natural barrier
in the way,

366
00:26:03,228 --> 00:26:08,667
more than 100 million Americans,
from Memphis to New York,

367
00:26:08,700 --> 00:26:11,603
swelter in the summer heat.

368
00:26:14,539 --> 00:26:16,775
This graphic,

369
00:26:16,808 --> 00:26:19,878
based on information
provided by satellites,

370
00:26:19,911 --> 00:26:23,582
depicts the interaction between
the atmosphere and the oceans

371
00:26:23,615 --> 00:26:26,184
as they connect in a global
pattern of circulation

372
00:26:26,217 --> 00:26:30,288
that results in our
local weather.

373
00:26:30,322 --> 00:26:32,591
SHUCKBURGH:
The satellite data shows that

374
00:26:32,624 --> 00:26:34,960
it's all one
interconnected system,

375
00:26:34,993 --> 00:26:36,795
but that in different parts
of the world,

376
00:26:36,828 --> 00:26:38,496
different processes
are happening.

377
00:26:38,530 --> 00:26:40,999
We can see the monsoons
and their effect.

378
00:26:49,040 --> 00:26:52,410
We can see the effects
on deserts

379
00:26:52,444 --> 00:26:55,113
in a different part
of the world.

380
00:26:59,651 --> 00:27:02,487
And that together shows us

381
00:27:02,520 --> 00:27:05,323
how water vapor is connecting
with life on earth.

382
00:27:17,302 --> 00:27:21,206
NARRATOR:
But this vast cycle of sunlight, water and land

383
00:27:21,239 --> 00:27:26,511
is just one pattern among many
on this planet we call home.

384
00:27:33,551 --> 00:27:37,989
A cycle with even
greater consequences

385
00:27:38,023 --> 00:27:42,827
for the long-term climate
involves extreme cold.

386
00:27:45,997 --> 00:27:50,301
To see how that works, we have
to turn the earth upside down

387
00:27:50,335 --> 00:27:52,337
and look at it from below.

388
00:28:03,248 --> 00:28:08,119
Antarctica remains the earth's
last great wilderness,

389
00:28:08,153 --> 00:28:11,923
a vast frozen continent
plunged in darkness

390
00:28:11,956 --> 00:28:16,127
for almost six months
of each year.

391
00:28:23,334 --> 00:28:25,070
In winter,
temperatures can drop

392
00:28:25,103 --> 00:28:28,873
below minus 110 degrees
Fahrenheit,

393
00:28:28,907 --> 00:28:32,310
and an incessant
100-mile-an-hour gale blows.

394
00:28:36,781 --> 00:28:39,451
It's hard to believe
that anything life-giving

395
00:28:39,484 --> 00:28:43,988
could start here
in this bleak place.

396
00:28:44,022 --> 00:28:48,326
But that's exactly
what happens.

397
00:28:54,966 --> 00:28:58,169
Antarctica's ice
plays a vital part

398
00:28:58,203 --> 00:29:00,405
in maintaining global climate,

399
00:29:00,438 --> 00:29:04,743
sustaining life even in lush,
warm jungles

400
00:29:04,776 --> 00:29:06,511
thousands of miles away.

401
00:29:12,751 --> 00:29:16,921
ABDALATI:
Antarctica is a fundamental element of the climate system.

402
00:29:16,955 --> 00:29:22,127
And while it may sit silently
and majestically

403
00:29:22,160 --> 00:29:26,097
at the edge of the planet
for very few to see,

404
00:29:26,131 --> 00:29:29,634
things go on there

405
00:29:29,667 --> 00:29:31,669
that spread out
all over the world,

406
00:29:31,703 --> 00:29:33,138
that affect the world
as a whole.

407
00:29:40,378 --> 00:29:43,848
NARRATOR:
It's a paradox that such a bleak and barren place

408
00:29:43,882 --> 00:29:46,751
is so critical
to life on our planet.

409
00:29:46,785 --> 00:29:53,024
On average, it's 43 degrees
colder than the North Pole.

410
00:29:53,057 --> 00:29:58,263
Why should Antarctica
be so much colder,

411
00:29:58,296 --> 00:30:02,467
and how does that affect
the rest of the world?

412
00:30:14,012 --> 00:30:17,048
The detectors on NASA's
polar-orbiting satellite <i>Suomi</i>

413
00:30:17,081 --> 00:30:19,651
provide part of the answer.

414
00:30:22,253 --> 00:30:23,721
The instruments sense

415
00:30:23,755 --> 00:30:27,025
in the infrared and ultraviolet
parts of the spectrum.

416
00:30:27,058 --> 00:30:30,795
They show that the poles receive
little of the sun's energy

417
00:30:30,829 --> 00:30:33,398
and reflect most of it
back out into space.

418
00:30:35,700 --> 00:30:39,137
That's one reason why the poles
stay cold.

419
00:30:39,170 --> 00:30:43,241
But there's another factor that
makes Antarctica colder still.

420
00:30:48,680 --> 00:30:50,715
This image has been
pieced together

421
00:30:50,748 --> 00:30:53,051
from 17 different satellites

422
00:30:53,084 --> 00:30:55,954
that sense the infrared,
or heat.

423
00:30:55,987 --> 00:30:58,823
The continental mass
of Antarctica

424
00:30:58,857 --> 00:31:02,527
lies beneath this swirling
maelstrom of cloud.

425
00:31:14,472 --> 00:31:18,009
A computer model of the data
shows what happens

426
00:31:18,042 --> 00:31:21,446
as the warm moist air
arriving from the tropics

427
00:31:21,479 --> 00:31:26,017
collides with the cold air
over the South Pole.

428
00:31:26,050 --> 00:31:32,323
The result is
a massive storm system.

429
00:31:32,357 --> 00:31:34,359
And just like a hurricane,

430
00:31:34,392 --> 00:31:38,196
it rotates as a result
of the spin of the earth.

431
00:31:38,229 --> 00:31:41,633
Only this is much larger
than a hurricane,

432
00:31:41,666 --> 00:31:45,770
4,000 miles in diameter.

433
00:31:50,141 --> 00:31:53,344
Where that cold air and warm air
meet high up in the atmosphere,

434
00:31:53,378 --> 00:31:56,648
the air starts to rotate
around Antarctica.

435
00:31:59,450 --> 00:32:01,286
The winds can be up
in the atmosphere

436
00:32:01,319 --> 00:32:04,188
as much as 200 miles an hour.

437
00:32:05,456 --> 00:32:08,960
NARRATOR:
This circulation pattern is called the polar jet,

438
00:32:08,993 --> 00:32:13,564
a ceaseless circle
of wind and storms.

439
00:32:13,598 --> 00:32:17,235
The relentless clockwise wind,
seen here in yellow,

440
00:32:17,268 --> 00:32:21,439
drives the seawater below,
shown in light blue.

441
00:32:25,677 --> 00:32:29,213
DAVID ADAMEC:
Those strong winds are sending a jet around in the ocean,

442
00:32:29,247 --> 00:32:30,748
and it's driving
an ocean circulation

443
00:32:30,782 --> 00:32:34,619
that is felt almost all the way
to the bottom of the ocean,

444
00:32:34,652 --> 00:32:36,120
two and a half miles deep.

445
00:32:41,025 --> 00:32:43,928
NARRATOR:
The Southern Ocean rings the continent

446
00:32:43,962 --> 00:32:48,599
with no land to interrupt
a vast body of moving water.

447
00:32:52,937 --> 00:32:57,976
This is the Antarctic
Circumpolar Current.

448
00:32:58,009 --> 00:33:01,379
And these are
the "Screaming Sixties,"

449
00:33:01,412 --> 00:33:05,249
the roughest, most dangerous
seas on the planet.

450
00:33:17,895 --> 00:33:22,500
Here, storms rage almost
every day of the year,

451
00:33:22,533 --> 00:33:25,503
whipping hundreds of trillions
of gallons of water

452
00:33:25,536 --> 00:33:28,740
into a ceaseless frenzy.

453
00:33:45,256 --> 00:33:48,826
Now the infrared instrument
on the <i>Aqua</i> satellite

454
00:33:48,860 --> 00:33:51,129
which senses atmospheric
temperature

455
00:33:51,162 --> 00:33:54,499
puts the pieces
of this puzzle together.

456
00:33:54,532 --> 00:33:56,434
The winds of the polar jet

457
00:33:56,467 --> 00:33:59,070
and the water
of the circumpolar current

458
00:33:59,103 --> 00:34:03,374
together form an impenetrable
barrier around Antarctica,

459
00:34:03,408 --> 00:34:06,010
isolating it from the rest
of the planet

460
00:34:06,044 --> 00:34:09,013
and depriving it of warmth.

461
00:34:09,047 --> 00:34:11,482
That is why the whole region

462
00:34:11,516 --> 00:34:15,753
remains exceptionally cold
all year round.

463
00:34:23,661 --> 00:34:27,565
ABDALATI:
What's incredible about what the satellites tell us

464
00:34:27,598 --> 00:34:29,534
is that the movement of air

465
00:34:29,567 --> 00:34:31,235
and actually the movement
of ocean current

466
00:34:31,269 --> 00:34:33,905
around the perimeter
of Antarctica

467
00:34:33,938 --> 00:34:39,544
isolates the continent
from the rest of the world.

468
00:34:39,577 --> 00:34:43,815
NARRATOR:
So why is this relentless cold so important to the planet

469
00:34:43,848 --> 00:34:46,784
way beyond Antarctica?

470
00:34:46,818 --> 00:34:50,855
The answer lies in a remarkable
property of water:

471
00:34:50,888 --> 00:34:53,524
what happens when it freezes.

472
00:34:58,863 --> 00:35:02,934
The <i>Aqua</i> satellite reveals
the start of the process.

473
00:35:02,967 --> 00:35:06,137
It sweeps the surface
with its microwave scanner,

474
00:35:06,170 --> 00:35:08,306
looking through the clouds

475
00:35:08,339 --> 00:35:13,845
to detect the distinct
signature of ice.

476
00:35:13,878 --> 00:35:15,980
SHUCKBURGH:
The microwave instruments on the satellite

477
00:35:16,013 --> 00:35:18,082
enable us to see through
the clouds

478
00:35:18,116 --> 00:35:20,952
to the sea ice around Antarctica
throughout the year.

479
00:35:20,985 --> 00:35:22,687
What's particularly incredible
about that is

480
00:35:22,720 --> 00:35:24,655
we're able to take measurements
of the sea ice

481
00:35:24,689 --> 00:35:27,792
in places where as scientists,
as humans, we can't even go.

482
00:35:27,825 --> 00:35:32,263
NARRATOR:
This satellite gives us an accurate picture

483
00:35:32,296 --> 00:35:35,066
of the extent of sea ice
around Antarctica

484
00:35:35,099 --> 00:35:37,935
over the course of a year.

485
00:35:48,079 --> 00:35:50,748
Seen here in summer,
Antarctica is nearly

486
00:35:50,781 --> 00:35:54,318
one and a half times the size
of the United States,

487
00:35:54,352 --> 00:35:56,721
covered in ice.

488
00:36:03,361 --> 00:36:07,532
But in winter,
it grows even more.

489
00:36:07,565 --> 00:36:11,435
Over five and a half million
square miles of ice form

490
00:36:11,469 --> 00:36:13,738
around the continent.

491
00:36:13,771 --> 00:36:17,675
It grows to the size
of all of Africa.

492
00:36:24,448 --> 00:36:27,418
This vast ice formation
has a profound effect

493
00:36:27,451 --> 00:36:29,854
on life across the planet.

494
00:36:29,887 --> 00:36:33,658
How can its impact
extend so far?

495
00:36:40,998 --> 00:36:45,002
One of the best places
to understand the power of ice

496
00:36:45,036 --> 00:36:47,104
is the huge bay

497
00:36:47,138 --> 00:36:51,142
along the northwestern coast
of Antarctica: the Weddell Sea.

498
00:36:55,179 --> 00:36:59,650
Here, a constant gale blows
and cools the seawater

499
00:36:59,684 --> 00:37:02,353
to freezing temperatures.

500
00:37:02,386 --> 00:37:05,323
Once the upper layer of ocean

501
00:37:05,356 --> 00:37:08,392
falls below 29 degrees
Fahrenheit,

502
00:37:08,426 --> 00:37:12,530
a critical threshold is crossed.

503
00:37:12,563 --> 00:37:17,568
The surface of the ocean
begins to freeze.

504
00:37:26,110 --> 00:37:32,383
(crackling)

505
00:37:44,662 --> 00:37:48,666
At a microscopic level,
tiny crystals start to grow,

506
00:37:48,699 --> 00:37:51,702
knitting themselves together.

507
00:37:51,736 --> 00:37:56,407
As the crystals bond,
they expel salt into the water.

508
00:38:01,012 --> 00:38:05,616
The salt forms brine that drips
down long, narrow tubes

509
00:38:05,650 --> 00:38:09,186
and holes in the ice
as it forms.

510
00:38:09,220 --> 00:38:15,059
The brine is denser than regular
seawater and it sinks downwards.

511
00:38:15,092 --> 00:38:16,727
As winter's grip tightens,

512
00:38:16,761 --> 00:38:20,398
the formation of ice
speeds up and spreads.

513
00:38:31,909 --> 00:38:35,012
Soon, large slicks appear
on the surface

514
00:38:35,046 --> 00:38:38,149
and thicken into a solid mass.

515
00:38:38,182 --> 00:38:40,685
What started as
a microscopic process

516
00:38:40,718 --> 00:38:44,288
can soon be seen from space.

517
00:38:52,496 --> 00:38:56,634
Each year, more than
200 billion tons of ice form

518
00:38:56,667 --> 00:38:58,869
in the Weddell Sea alone,

519
00:38:58,903 --> 00:39:02,907
releasing tens of trillions
of tons of dense brine

520
00:39:02,940 --> 00:39:05,209
into the ocean.

521
00:39:05,242 --> 00:39:08,346
The fate of all this brine
is a mystery.

522
00:39:13,918 --> 00:39:17,822
The crucial question is
where does it all go?

523
00:39:28,065 --> 00:39:30,434
A satellite called <i>Jason,</i>

524
00:39:30,468 --> 00:39:33,804
jointly operated by NASA
and the French space agency,

525
00:39:33,838 --> 00:39:36,707
is providing new answers.

526
00:39:36,741 --> 00:39:40,344
<i>Jason</i> bounces radar signals
off the surface of the ocean

527
00:39:40,378 --> 00:39:42,780
to measure its height.

528
00:39:42,813 --> 00:39:46,250
The instrument also reveals

529
00:39:46,283 --> 00:39:50,388
the shape of the sea floor
far below.

530
00:39:53,457 --> 00:39:57,161
We can make very accurate maps
of submarine bathymetry.

531
00:39:57,194 --> 00:39:58,829
But we don't do that directly;

532
00:39:58,863 --> 00:40:02,433
we do that by measuring the
surface of the sea from space,

533
00:40:02,466 --> 00:40:06,003
very, very accurately
and over time.

534
00:40:06,036 --> 00:40:09,273
NARRATOR:
<i>Jason's</i> radar is so precise

535
00:40:09,306 --> 00:40:11,709
that it can detect
minute changes

536
00:40:11,742 --> 00:40:13,444
in the level of the sea surface

537
00:40:13,477 --> 00:40:17,681
produced by the peaks and
valleys of the terrain below.

538
00:40:17,715 --> 00:40:21,519
The data makes it possible
to map the ocean floor.

539
00:40:21,552 --> 00:40:25,089
ADAMEC:
You have a satellite that's up there, 500 miles up in space,

540
00:40:25,122 --> 00:40:27,525
and it's returning an accuracy

541
00:40:27,558 --> 00:40:30,194
of a little less
than half an inch.

542
00:40:30,227 --> 00:40:31,896
What that means is, you know,

543
00:40:31,929 --> 00:40:36,934
I've stuck this instrument
in Washington, D.C., say,

544
00:40:36,967 --> 00:40:39,970
and I'm looking at a crowd
of people in Boston

545
00:40:40,004 --> 00:40:42,840
and I can tell you
whether or not their toes

546
00:40:42,873 --> 00:40:44,909
are over the curb or not.

547
00:40:44,942 --> 00:40:46,710
That's what this satellite
is doing.

548
00:40:54,018 --> 00:40:55,486
NARRATOR:
The satellite data

549
00:40:55,519 --> 00:40:58,155
allows scientists to make
a three-dimensional map

550
00:40:58,189 --> 00:41:01,692
of the ocean floor
beneath the Weddell Sea.

551
00:41:01,725 --> 00:41:06,697
It reveals a vast chasm,
two miles deep,

552
00:41:06,730 --> 00:41:10,167
off Antarctica's
continental shelf.

553
00:41:10,201 --> 00:41:13,871
As the brine descends
into the ocean,

554
00:41:13,904 --> 00:41:17,875
it eventually falls over
this precipice.

555
00:41:17,908 --> 00:41:20,845
Other sensors attached
to the sea floor

556
00:41:20,878 --> 00:41:24,548
track the flow of the brine
as it sinks.

557
00:41:29,553 --> 00:41:32,423
SHUCKBURGH:
What we're really excited about is that

558
00:41:32,456 --> 00:41:34,225
we're able to take that data

559
00:41:34,258 --> 00:41:36,794
that shows us what the bottom
of the ocean looks like

560
00:41:36,827 --> 00:41:39,697
and combine it with data
from sensors under the water.

561
00:41:39,730 --> 00:41:43,667
And that enables us
to look at the dense water

562
00:41:43,701 --> 00:41:46,103
and where it goes.

563
00:41:48,572 --> 00:41:52,109
NARRATOR:
Combining data from satellites and undersea instruments,

564
00:41:52,142 --> 00:41:54,945
scientists can reconstruct
what is happening

565
00:41:54,979 --> 00:41:57,381
hidden beneath the ice.

566
00:41:57,414 --> 00:41:59,116
What they learn is astounding.

567
00:42:09,727 --> 00:42:12,496
One trillion gallons
of salty brine

568
00:42:12,530 --> 00:42:16,200
plunge down through
the Weddell Sea every hour

569
00:42:16,233 --> 00:42:21,639
a torrent equivalent to the
volume of 500 Niagara Falls.

570
00:42:28,846 --> 00:42:30,915
The brine spreads out
towards the edge

571
00:42:30,948 --> 00:42:33,517
of the Antarctic
continental shelf

572
00:42:33,551 --> 00:42:38,455
and then falls into the chasm
revealed by <i>Jason.</i>

573
00:42:38,489 --> 00:42:44,094
A vast submarine waterfall
plummets downward.

574
00:42:52,236 --> 00:42:54,171
The cold, dense brine

575
00:42:54,204 --> 00:42:58,042
falls slowly, silently,
into the abyss,

576
00:42:58,075 --> 00:43:03,547
two miles down
to the ocean floor below.

577
00:43:03,581 --> 00:43:08,385
It will not resurface
for hundreds of years.

578
00:43:34,178 --> 00:43:38,582
What happens to the brine next
is still being investigated.

579
00:43:38,616 --> 00:43:41,919
But computer models
combined with satellite data

580
00:43:41,952 --> 00:43:45,522
are helping scientists
to figure out where it goes.

581
00:43:50,661 --> 00:43:56,333
This animation shows the
undersea current in action.

582
00:43:56,367 --> 00:43:58,902
The purple area is the brine.

583
00:43:58,936 --> 00:44:01,205
The outflow from Antarctica

584
00:44:01,238 --> 00:44:04,341
drives the salty water
towards the equator,

585
00:44:04,375 --> 00:44:07,244
along the sea floor.

586
00:44:15,719 --> 00:44:20,257
ADAMEC:
All the water in the bottom of every ocean around the globe

587
00:44:20,290 --> 00:44:26,096
has its start within six miles
of the Antarctic continent.

588
00:44:30,834 --> 00:44:37,007
It creates the coldest, densest
water that's on the planet.

589
00:44:44,048 --> 00:44:46,750
NARRATOR:
The cold, salty liquid

590
00:44:46,784 --> 00:44:50,454
becomes part of a worldwide
circulation system,

591
00:44:50,487 --> 00:44:55,125
stirring and cooling
all the world's oceans.

592
00:44:55,159 --> 00:44:59,797
Leaving Antarctica,
it has embarked on a journey

593
00:44:59,830 --> 00:45:04,001
that could take 1,000 years
to complete.

594
00:45:04,034 --> 00:45:07,871
As it migrates
towards the equator,

595
00:45:07,905 --> 00:45:11,308
the cold bottom current mixes
with fresher and warmer water

596
00:45:11,341 --> 00:45:13,510
and slowly rises.

597
00:45:13,544 --> 00:45:17,581
It then joins
other ocean currents

598
00:45:17,614 --> 00:45:22,486
and eventually returns south,
where it cools once more.

599
00:45:22,519 --> 00:45:25,089
Finally, returning
to Antarctica,

600
00:45:25,122 --> 00:45:29,493
the seawater freezes
and releases its salt again,

601
00:45:29,526 --> 00:45:31,528
completing the cycle.

602
00:45:31,562 --> 00:45:37,601
It's an endless loop that is
critical to the whole planet.

603
00:45:40,370 --> 00:45:43,941
ABDALATI:
The importance of dense water in Antarctica is that

604
00:45:43,974 --> 00:45:50,114
it really forms the basis
of global ocean circulation.

605
00:45:50,147 --> 00:45:52,750
The temperature
and the salt combine

606
00:45:52,783 --> 00:45:55,486
to cause sinking and rising
in different parts,

607
00:45:55,519 --> 00:45:58,388
which sets up
this conveyor belt,

608
00:45:58,422 --> 00:46:02,960
this interaction of
all of the ocean water.

609
00:46:08,966 --> 00:46:13,337
NARRATOR:
In the Arctic, frigid winter winds cause the ocean to freeze.

610
00:46:13,370 --> 00:46:17,207
The North Atlantic currents
cool and sink to the bottom,

611
00:46:17,241 --> 00:46:20,210
then head south again.

612
00:46:20,244 --> 00:46:24,381
All over the world, slow-moving
currents of seawater like this

613
00:46:24,414 --> 00:46:27,718
regulate the average
temperatures of the oceans

614
00:46:27,751 --> 00:46:29,486
to whin one degree.

615
00:46:32,723 --> 00:46:35,793
This stability has
a profound effect on life

616
00:46:35,826 --> 00:46:38,929
all across the world.

617
00:46:46,270 --> 00:46:50,274
This NASA simulation shows
the surface of the entire ocean,

618
00:46:50,307 --> 00:46:53,977
a web of currents
in constant motion.

619
00:47:00,317 --> 00:47:04,755
But satellites show us that
the oceans don't work alone.

620
00:47:04,788 --> 00:47:10,160
The currents affect the air,
the atmosphere,

621
00:47:10,194 --> 00:47:13,630
that sits above them.

622
00:47:13,664 --> 00:47:17,201
The ocean and atmosphere
are intimately connected.

623
00:47:21,872 --> 00:47:25,275
For instance,
the Gulf Stream

624
00:47:25,309 --> 00:47:28,178
takes warm water
from the Gulf of Mexico

625
00:47:28,212 --> 00:47:30,981
north to the eastern
United States and Europe,

626
00:47:31,014 --> 00:47:34,985
generating warm air.

627
00:47:35,018 --> 00:47:37,254
On the other side
of the world,

628
00:47:37,287 --> 00:47:39,690
another current
called the Kuroshio

629
00:47:39,723 --> 00:47:43,594
carries heat from China
north to Japan.

630
00:47:47,564 --> 00:47:49,499
It's a global process,

631
00:47:49,533 --> 00:47:54,371
ocean currents distributing heat
around the planet.

632
00:47:56,373 --> 00:47:58,642
The climate we live in

633
00:47:58,675 --> 00:48:02,179
is a result of ocean
circulation patterns.

634
00:48:02,212 --> 00:48:04,648
The reason in the United States

635
00:48:04,681 --> 00:48:07,618
that North Carolina
and South Carolina are warm

636
00:48:07,651 --> 00:48:09,753
is because there is
the Gulf Stream.

637
00:48:09,786 --> 00:48:11,488
And the reason there's
a Gulf Stream

638
00:48:11,521 --> 00:48:13,757
really takes root in Antarctica.

639
00:48:16,793 --> 00:48:20,764
NARRATOR:
As a major engine driving the world's ocean currents,

640
00:48:20,797 --> 00:48:23,700
Antarctica helps protect
Earth's climate

641
00:48:23,734 --> 00:48:26,470
from wild swings
in temperature.

642
00:48:26,503 --> 00:48:28,572
The constant,
dependable circulation

643
00:48:28,605 --> 00:48:30,874
of the oceans around the globe

644
00:48:30,908 --> 00:48:33,810
and the relatively stable
temperatures it produces

645
00:48:33,844 --> 00:48:37,114
have made Earth
a hospitable planet.

646
00:48:37,147 --> 00:48:42,386
Long-term stability provided
time for life to flourish

647
00:48:42,419 --> 00:48:47,557
and complex animals
and plants to evolve.

648
00:48:52,129 --> 00:48:56,700
And this is how a process
that began with Antarctic ice

649
00:48:56,733 --> 00:49:00,671
continues to sustain our world.

650
00:49:00,704 --> 00:49:06,076
ABDALATI:
When you put it all together, you get a story

651
00:49:06,109 --> 00:49:08,745
of how ocean circulation affects
climate and weather

652
00:49:08,779 --> 00:49:11,982
and what that means today,
tomorrow

653
00:49:12,015 --> 00:49:14,952
and 20 years out
into the future.

654
00:49:30,067 --> 00:49:32,202
(rumbling)

655
00:49:40,677 --> 00:49:43,213
NARRATOR:
But ocean currents and the atmosphere

656
00:49:43,246 --> 00:49:45,482
are not the only players.

657
00:49:45,515 --> 00:49:47,484
Beneath the sea floor,

658
00:49:47,517 --> 00:49:50,921
forces inside the earth
are a crucial source

659
00:49:50,954 --> 00:49:54,725
for the basic materials
that nurture life.

660
00:49:54,758 --> 00:49:58,362
This hidden mechanism
is driven by ceaseless,

661
00:49:58,395 --> 00:50:01,598
often violent activity.

662
00:50:11,475 --> 00:50:15,212
Two recent examples:

663
00:50:15,245 --> 00:50:20,083
A magnitude nine earthquake
strikes Japan in 2011.

664
00:50:20,117 --> 00:50:23,153
An entire section
of the country

665
00:50:23,186 --> 00:50:25,422
moves eight feet
towards North America.

666
00:50:35,065 --> 00:50:41,071
A year earlier, 2,500 miles to
the south in Papua New Guinea,

667
00:50:41,104 --> 00:50:44,574
the volcano Rabaul erupts.

668
00:50:44,608 --> 00:50:49,246
It fires a vast plume of ash
high into the atmosphere.

669
00:51:00,690 --> 00:51:06,229
These are catastrophic,
hugely destructive events

670
00:51:06,263 --> 00:51:09,299
with an enormous cost
in human lives.

671
00:51:09,332 --> 00:51:12,035
But the natural forces
behind these disasters

672
00:51:12,069 --> 00:51:15,105
also provide the materials

673
00:51:15,138 --> 00:51:19,543
we and other living organisms
need to survive.

674
00:51:22,312 --> 00:51:27,484
And satellites help show us
how this happens.

675
00:51:31,922 --> 00:51:35,058
Canada's <i>RADARSAT</i> is
one of several satellites

676
00:51:35,092 --> 00:51:37,694
that use highly sensitive radar

677
00:51:37,727 --> 00:51:41,898
to map the earth's surface
in three dimensions.

678
00:51:41,932 --> 00:51:46,303
Bouncing radio waves off
the terrain below,

679
00:51:46,336 --> 00:51:50,574
these satellites continually
sweep the surface of the globe.

680
00:51:58,949 --> 00:52:02,652
They can measure the height
of the earth's surface every day

681
00:52:02,686 --> 00:52:07,858
to an accuracy of less
than a quarter of an inch.

682
00:52:07,891 --> 00:52:10,260
When the data is plotted
over time,

683
00:52:10,293 --> 00:52:12,529
we can see in fine detail

684
00:52:12,562 --> 00:52:15,465
how the earth's crust
is constantly moving.

685
00:52:19,970 --> 00:52:22,372
This is the surface
of the crater

686
00:52:22,405 --> 00:52:24,975
atop Mount St. Helens
in Washington state.

687
00:52:25,008 --> 00:52:29,513
Animation reveals how it swells
over the course of three weeks,

688
00:52:29,546 --> 00:52:34,251
driven by a surge of molten
magma beneath the crater.

689
00:52:39,589 --> 00:52:42,526
Satellites can actually see
the crustal plates moving now.

690
00:52:42,559 --> 00:52:45,061
We can see bulges and dips

691
00:52:45,095 --> 00:52:47,631
where the magma is moving around
underneath the crust.

692
00:52:47,664 --> 00:52:53,637
NARRATOR:
This animation shows the swelling of Mount Etna in Italy

693
00:52:53,670 --> 00:52:57,707
as magma accumulates beneath it
over nine years.

694
00:52:57,741 --> 00:53:01,745
When the volcano erupts,
the land sinks back.

695
00:53:01,778 --> 00:53:03,947
SELLERS:
So we're getting a picture now

696
00:53:03,980 --> 00:53:06,850
of what the world looks like
under the crust

697
00:53:06,883 --> 00:53:09,619
and how that affects
the other dynamic processes

698
00:53:09,653 --> 00:53:11,288
of the so-called solid earth.

699
00:53:16,159 --> 00:53:21,164
NARRATOR:
Every day, dozens of volcanoes around the world are erupting,

700
00:53:21,198 --> 00:53:24,668
while 4,000 earthquakes
shake the ground.

701
00:53:24,701 --> 00:53:27,204
Our earth is dynamic,

702
00:53:27,237 --> 00:53:30,874
constantly ejecting gases
and magma from its depths.

703
00:53:30,907 --> 00:53:35,512
And some of this activity
has a vital impact on life.

704
00:53:35,545 --> 00:53:37,814
The secret to understanding how

705
00:53:37,847 --> 00:53:41,117
lies deep beneath
the ocean's surface.

706
00:53:43,153 --> 00:53:46,823
Here, a crucial chemical
reaction takes place

707
00:53:46,856 --> 00:53:50,427
between molten rock
and deep ocean water.

708
00:54:06,409 --> 00:54:09,746
The <i>Jason</i> satellite's
sea surface-mapping radar

709
00:54:09,779 --> 00:54:12,515
reveals a chain
of active volcanoes

710
00:54:12,549 --> 00:54:17,654
a mile and a half down, at the
bottom of the Pacific Ocean.

711
00:54:17,687 --> 00:54:19,823
This is where
that critical interaction

712
00:54:19,856 --> 00:54:23,727
between molten rock
and freezing water takes place.

713
00:54:25,996 --> 00:54:30,367
This footage was taken with
a remotely operated submarine,

714
00:54:30,400 --> 00:54:33,403
also called <i>Jason.</i>

715
00:54:33,436 --> 00:54:35,639
Lava and superheated gases

716
00:54:35,672 --> 00:54:38,141
spill out of cracks
in the ocean floor,

717
00:54:38,174 --> 00:54:40,677
known as hydrothermal vents.

718
00:54:40,710 --> 00:54:43,880
<i>Jason</i> reveals what happens

719
00:54:43,913 --> 00:54:47,784
when cold ocean water
penetrates into the cracks.

720
00:54:47,817 --> 00:54:51,921
A magma chamber below
heats the water

721
00:54:51,955 --> 00:54:55,592
to up to 750 degrees
Fahrenheit.

722
00:54:55,625 --> 00:54:59,896
In the pressure-cooker
environment inside the cracks,

723
00:54:59,929 --> 00:55:06,870
the dense salty water actually
dissolves the solid rock.

724
00:55:06,903 --> 00:55:10,607
Complex chemical reactions
take place,

725
00:55:10,640 --> 00:55:14,377
producing minerals
containing sulfur and iron.

726
00:55:14,411 --> 00:55:19,349
These are nutrients that living
organisms need to survive.

727
00:55:19,382 --> 00:55:24,721
The seawater, now loaded with
minerals from inside the earth,

728
00:55:24,754 --> 00:55:27,757
streams out of the
hydrothermal vents.

729
00:55:27,791 --> 00:55:31,494
These nutrients feed
a thriving ecosystem

730
00:55:31,528 --> 00:55:36,099
that includes shrimp and exotic
creatures like tubeworms.

731
00:55:42,339 --> 00:55:47,677
The deep ocean currents carry
the leftover nutrients away.

732
00:55:47,711 --> 00:55:53,383
Over thousands of years, they
circulate through the oceans,

733
00:55:53,416 --> 00:55:55,919
ultimately rising to the surface

734
00:55:55,952 --> 00:56:01,758
and contributing to an amazing
explosion of life.

735
00:56:05,662 --> 00:56:09,032
And we can see this activity
with NASA's <i>Aqua</i> satellite,

736
00:56:09,065 --> 00:56:10,834
which is equipped
with instruments

737
00:56:10,867 --> 00:56:12,836
that observe the earth

738
00:56:12,869 --> 00:56:16,439
in many wavelengths
of the electromagnetic spectrum.

739
00:56:16,473 --> 00:56:22,078
One tool is called MODIS.

740
00:56:22,112 --> 00:56:26,349
MODIS is pretty much the crown
jewel of the <i>Aqua</i> satellite.

741
00:56:26,383 --> 00:56:27,984
It's an enormous scanner.

742
00:56:28,017 --> 00:56:30,320
So it basically covers
the whole world every day.

743
00:56:35,358 --> 00:56:38,294
NARRATOR:
MODIS scans the ocean in the infrared

744
00:56:38,328 --> 00:56:41,064
and the visible portions
of the spectrum.

745
00:56:44,134 --> 00:56:48,304
It can detect extremely subtle
changes in the temperature

746
00:56:48,338 --> 00:56:50,240
and color of the water.

747
00:56:54,310 --> 00:56:57,480
So what we have in space
is an instrument

748
00:56:57,514 --> 00:57:01,518
that looks at very, very small
parts of the spectrum,

749
00:57:01,551 --> 00:57:03,987
and we measure how much light
comes back

750
00:57:04,020 --> 00:57:06,156
in each part of the spectrum.

751
00:57:10,994 --> 00:57:13,763
NARRATOR:
Looking down at the west coast of South America,

752
00:57:13,797 --> 00:57:16,533
MODIS detects an upwelling
of cold water

753
00:57:16,566 --> 00:57:20,136
150 miles west of Peru.

754
00:57:20,170 --> 00:57:23,773
Then it detects a particular
shade of green.

755
00:57:23,807 --> 00:57:27,076
This identifies the source
as chlorophyll,

756
00:57:27,110 --> 00:57:30,313
a sign of plant life.

757
00:57:30,346 --> 00:57:33,716
It's clear that the satellite
has spotted a massive bloom

758
00:57:33,750 --> 00:57:37,954
of tiny organisms
called phytoplankton.

759
00:57:37,987 --> 00:57:41,591
Just below the surface, these
phytoplankton are absorbing

760
00:57:41,624 --> 00:57:45,862
the rich soup of minerals that
have come from the deep ocean.

761
00:57:57,474 --> 00:57:59,576
And with light from the Sun,

762
00:57:59,609 --> 00:58:02,278
and carbon from the carbon
dioxide in the air,

763
00:58:02,312 --> 00:58:05,014
they multiply by the billions.

764
00:58:10,954 --> 00:58:14,958
As MODIS shows, the plankton
multiply so quickly

765
00:58:14,991 --> 00:58:20,063
that in just 24 hours,
500 square miles of ocean

766
00:58:20,096 --> 00:58:23,600
have turned to this
distinctive green color.

767
00:58:32,642 --> 00:58:34,377
GENE FELDMAN:
They replicate very, very fast.

768
00:58:34,410 --> 00:58:37,647
So you can have a plankton bloom

769
00:58:37,680 --> 00:58:40,350
that doubles over the course
of a day

770
00:58:40,383 --> 00:58:43,820
and can cover hundreds or
thousands of kilometers

771
00:58:43,853 --> 00:58:46,523
of the ocean surface.

772
00:58:50,193 --> 00:58:52,395
NARRATOR:
It's the minerals from beneath the earth's crust

773
00:58:52,428 --> 00:58:57,000
that have helped fuel this
vast explosion of plankton--

774
00:58:57,033 --> 00:59:02,071
over 800 thousand tons of living
material.

775
00:59:02,105 --> 00:59:05,275
And that's only the beginning.

776
00:59:05,308 --> 00:59:10,079
This plankton is the base of
the food chain for marine life.

777
00:59:10,113 --> 00:59:13,583
The bloom triggers one of
the largest feeding frenzies

778
00:59:13,616 --> 00:59:15,552
on earth.

779
00:59:28,765 --> 00:59:31,267
Trillions of anchovies
and sardines

780
00:59:31,301 --> 00:59:33,336
feast on the tiny organisms.

781
00:59:41,210 --> 00:59:44,047
They, in turn,
attract larger predators

782
00:59:44,080 --> 00:59:45,949
to one of the densest
concentrations

783
00:59:45,982 --> 00:59:47,817
of marine life anywhere.

784
00:59:51,387 --> 00:59:54,324
Sharks converge.

785
00:59:54,357 --> 01:00:00,296
And even birds, flying above,
dive down to join the feast.

786
01:00:04,467 --> 01:00:08,771
And up above, humans are here,
too, taking advantage

787
01:00:08,805 --> 01:00:12,308
of one of the world's most
productive fishing grounds.

788
01:00:13,843 --> 01:00:16,412
The satellite data reveals
similar upwellings

789
01:00:16,446 --> 01:00:21,017
all around the world, delivering
nutrients, seen here in pink,

790
01:00:21,050 --> 01:00:23,453
into the surface waters.

791
01:00:23,486 --> 01:00:27,056
Each upwelling triggers
a plankton bloom.

792
01:00:30,827 --> 01:00:32,428
FELDMAN:
Phytoplankton provide that key link

793
01:00:32,462 --> 01:00:35,765
between this energy out here,

794
01:00:35,798 --> 01:00:41,037
the raw materials
that this planet holds

795
01:00:41,070 --> 01:00:45,842
and the food engine
that allows life to flourish.

796
01:00:50,413 --> 01:00:53,282
NARRATOR:
These vast green ribbons of plankton

797
01:00:53,316 --> 01:00:58,521
can cover as much as a fifth
of the world's ocean surfaces,

798
01:00:58,554 --> 01:01:02,825
about 45 billion tons of biomass
every year.

799
01:01:02,859 --> 01:01:06,295
The plankton are one link
in a chain of life

800
01:01:06,329 --> 01:01:09,632
that begins deep beneath
the seafloor.

801
01:01:15,738 --> 01:01:17,874
The most important plant life
on this planet

802
01:01:17,907 --> 01:01:20,209
are these microscopic
little green plants

803
01:01:20,243 --> 01:01:21,944
that float in the ocean.

804
01:01:26,916 --> 01:01:29,285
NARRATOR:
Plankton may be key to life,

805
01:01:29,318 --> 01:01:32,221
but they themselves
don't live long.

806
01:01:35,358 --> 01:01:38,294
MODIS shows how,
in just 72 hours,

807
01:01:38,327 --> 01:01:41,998
a bloom can rapidly weaken
and fade.

808
01:01:55,111 --> 01:01:57,580
All the plankton
that have not been eaten

809
01:01:57,613 --> 01:02:01,150
die and sink into the abyss.

810
01:02:01,184 --> 01:02:04,620
They take their precious
minerals with them

811
01:02:04,654 --> 01:02:07,423
all the way back
to the ocean floor.

812
01:02:17,100 --> 01:02:19,769
Here they will remain
for millennia,

813
01:02:19,802 --> 01:02:24,774
a thick carpeting of tiny
carcasses half a mile deep.

814
01:02:27,977 --> 01:02:31,881
Some of the minerals may
ultimately be recycled.

815
01:02:31,914 --> 01:02:35,118
Some may emerge through
hydrothermal vents again,

816
01:02:35,151 --> 01:02:38,187
millions of years from now.

817
01:02:38,221 --> 01:02:39,522
But some plankton,

818
01:02:39,555 --> 01:02:42,425
through yet another
extraordinary chain of events,

819
01:02:42,458 --> 01:02:45,728
will deliver their precious
cargo of nutrients

820
01:02:45,762 --> 01:02:51,467
not just to life in the ocean,
but also to life on land.

821
01:02:59,342 --> 01:03:04,213
Half a world away from the coast
of Peru, where plankton bloom,

822
01:03:04,247 --> 01:03:10,353
lies the Sahara Desert
in North Africa.

823
01:03:10,386 --> 01:03:12,088
The Sahara is enormous--

824
01:03:12,121 --> 01:03:15,725
it makes up a tenth
of the African continent.

825
01:03:15,758 --> 01:03:20,229
It's one of the driest
and dustiest places on earth.

826
01:03:20,263 --> 01:03:24,267
Surprisingly, the remains
of ancient plankton are here,

827
01:03:24,300 --> 01:03:26,803
hidden in this arid landscape.

828
01:03:34,243 --> 01:03:37,713
It is May,
the hottest month of all.

829
01:03:37,747 --> 01:03:41,350
Camel herders travel through
one of the most exposed regions

830
01:03:41,384 --> 01:03:46,122
of the Sahara:
the Bodele Depression.

831
01:03:46,155 --> 01:03:48,491
Six thousand years ago,

832
01:03:48,524 --> 01:03:52,895
this was covered by the world's
largest freshwater lake.

833
01:03:52,929 --> 01:03:58,100
The floor of the lake is covered
with the ancient remains

834
01:03:58,134 --> 01:04:03,940
of plankton-- called diatomite--
laid down in a much earlier age,

835
01:04:03,973 --> 01:04:06,075
when an ocean covered
the region.

836
01:04:15,885 --> 01:04:19,288
With its eye on the earth
from 400 miles above,

837
01:04:19,322 --> 01:04:24,060
NASA's <i>Landsat 7</i> is one of the
latest generation of satellites

838
01:04:24,093 --> 01:04:28,064
studying the composition of
rocks that make up our planet.

839
01:04:31,868 --> 01:04:35,972
It sweeps the Bodele, producing
these high resolution pictures

840
01:04:36,005 --> 01:04:40,109
in multiple wavelengths
of visible light.

841
01:04:40,142 --> 01:04:42,378
The white expanse
is the diatomite

842
01:04:42,411 --> 01:04:44,480
on the bed of the lake.

843
01:04:47,783 --> 01:04:50,519
The size of the lake is over
a thousand kilometers long

844
01:04:50,553 --> 01:04:52,455
and 600 kilometers wide.

845
01:04:52,488 --> 01:04:56,459
But with a satellite image,
we can see the whole extent

846
01:04:56,492 --> 01:04:58,761
of the basin on a series
of images

847
01:04:58,794 --> 01:05:01,697
and visualize that on a computer
in a matter of minutes.

848
01:05:04,333 --> 01:05:06,135
NARRATOR:
The satellite image analysis

849
01:05:06,168 --> 01:05:10,673
shows over 24,000 square miles
of sediment,

850
01:05:10,706 --> 01:05:15,511
all of it diatomite.

851
01:05:15,544 --> 01:05:17,413
We can map where the diatomite
sedime is

852
01:05:17,446 --> 01:05:18,514
on the floor of the lake.

853
01:05:23,486 --> 01:05:27,523
NARRATOR:
The diatomite from the plankton is a rich source of phosphorous,

854
01:05:27,556 --> 01:05:35,865
an element needed by all living
things to produce energy.

855
01:05:35,898 --> 01:05:38,901
But for this nutrient to
re-enter the chain of life,

856
01:05:38,935 --> 01:05:41,504
it must first embark
on a long journey

857
01:05:41,537 --> 01:05:43,706
that can be seen from space.

858
01:05:56,652 --> 01:06:01,357
The journey begins here on the
ancient lakebed in the Sahara.

859
01:06:01,390 --> 01:06:06,762
The wind sweeps up a few flakes
of diatomite into the air.

860
01:06:06,796 --> 01:06:10,066
The flakes fracture
into a fine powder

861
01:06:10,099 --> 01:06:14,070
and are carried off by the wind.

862
01:06:14,103 --> 01:06:16,272
A dust storm builds.

863
01:06:26,949 --> 01:06:32,989
22,000 miles above, the European
weather satellite <i>Meteosat 8</i>

864
01:06:33,022 --> 01:06:36,125
looks down from its
geostationary orbit.

865
01:06:43,199 --> 01:06:45,434
It records a daily pulse of dust

866
01:06:45,468 --> 01:06:50,973
rising off the Bodele
Depression.

867
01:06:51,007 --> 01:06:53,776
Here it's visible
as a whitish dust cloud

868
01:06:53,809 --> 01:06:56,779
lifting from the desert
with clockwork regularity

869
01:06:56,812 --> 01:06:58,647
at noon each day.

870
01:07:02,418 --> 01:07:06,122
BRISTOW:
Although the individual particles of dust are minute--

871
01:07:06,155 --> 01:07:08,657
they're hundredths or
thousandths of a millimeter

872
01:07:08,691 --> 01:07:12,628
in diameter-- there are such
vast clouds of this dust

873
01:07:12,661 --> 01:07:15,631
that you can see it
on satellite images.

874
01:07:23,339 --> 01:07:26,542
NARRATOR:
The dust cloud is over a hundred stories high

875
01:07:26,575 --> 01:07:31,080
and 200 miles wide.

876
01:07:32,948 --> 01:07:36,552
From here it will head west
on an epic journey.

877
01:07:43,759 --> 01:07:49,031
Seen from space,
the dust is blown across Africa.

878
01:07:53,335 --> 01:07:58,407
At the Atlantic coast, it's
drawn up high into the sky.

879
01:08:01,277 --> 01:08:05,047
This simulation,
based on satellite data,

880
01:08:05,081 --> 01:08:09,819
shows how prevailing winds carry
the dust cloud west and south

881
01:08:09,852 --> 01:08:13,289
3,000 miles across the Atlantic.

882
01:08:21,363 --> 01:08:28,270
As much as 7,000 tons of dust
are airborne at any one time.

883
01:08:28,304 --> 01:08:31,974
The destination is set
by the winds:

884
01:08:32,007 --> 01:08:35,044
South America and the Amazon.

885
01:08:38,114 --> 01:08:42,118
We're taking literally thousands
of tons of this dust,

886
01:08:42,151 --> 01:08:43,652
which is containing phosphate,

887
01:08:43,686 --> 01:08:46,122
and exporting that
from the Bodele.

888
01:08:46,155 --> 01:08:48,457
The wind is carrying it out

889
01:08:48,491 --> 01:08:52,394
across the Atlantic
to fertilize the Amazon.

890
01:08:56,999 --> 01:08:59,902
NARRATOR:
Here in these clouds high above the rainforest,

891
01:08:59,935 --> 01:09:05,875
what was once living plankton
reaches the end of its journey.

892
01:09:05,908 --> 01:09:07,610
The minerals in the dust,

893
01:09:07,643 --> 01:09:10,746
which include energy-giving
phosphorous,

894
01:09:10,779 --> 01:09:12,781
dissolve into water droplets

895
01:09:12,815 --> 01:09:16,085
and fall to the Amazon in rain.

896
01:09:23,459 --> 01:09:27,830
BRISTOW:
Areas like the Amazon jungle, although they appear very rich,

897
01:09:27,863 --> 01:09:32,034
the soils are actually very
depleted, they've been leached.

898
01:09:32,067 --> 01:09:35,504
And one of the things that
they're short on is phosphate.

899
01:09:41,110 --> 01:09:43,546
NARRATOR:
Rain falls incessantly

900
01:09:43,579 --> 01:09:45,748
throughout the Amazon's
wet season,

901
01:09:45,781 --> 01:09:50,553
delivering thousands of tons of
phosphate into the forest below.

902
01:09:54,490 --> 01:09:58,227
It passes into the soil
and the roots of the trees,

903
01:09:58,260 --> 01:10:01,463
nourishing the rain forest.

904
01:10:02,932 --> 01:10:05,634
The effect of all this
natural fertilizer

905
01:10:05,668 --> 01:10:08,270
can be seen clearly from orbit.

906
01:10:13,976 --> 01:10:18,247
<i>Terra</i> is the twin
of the <i>Aqua</i> satellite.

907
01:10:18,280 --> 01:10:21,617
It circles the earth
every 99 minutes,

908
01:10:21,650 --> 01:10:24,820
monitoring how fast vegetation
is growing.

909
01:10:27,089 --> 01:10:30,059
SELLERS:
We can see all the green vegetation on earth--

910
01:10:30,092 --> 01:10:32,027
wall to wall, every day--

911
01:10:32,061 --> 01:10:34,797
and it tells you almost
everything you want to know

912
01:10:34,830 --> 01:10:38,200
about the state of life
on earth.

913
01:10:40,903 --> 01:10:42,905
NARRATOR:
With its color scanner,

914
01:10:42,938 --> 01:10:46,442
<i>Terra</i> can see the effect of
the Sahara dust on the Amazon

915
01:10:46,475 --> 01:10:48,110
at the end of the rainy season.

916
01:10:50,279 --> 01:10:53,482
It observes an increase
in the distinctive green color

917
01:10:53,515 --> 01:10:55,784
of chlorophyll.

918
01:10:55,818 --> 01:10:58,120
Like the plankton blooms
in the ocean,

919
01:10:58,153 --> 01:11:01,423
the forest is kicking
into overdrive...

920
01:11:03,392 --> 01:11:07,630
watered by rain
and nourished by the minerals

921
01:11:07,663 --> 01:11:10,899
borne across the Atlantic
by the dust cloud.

922
01:11:13,969 --> 01:11:18,707
For every leaf that exists now,
three more will grow in a week.

923
01:11:18,741 --> 01:11:21,810
It's the culmination
of a chain of events

924
01:11:21,844 --> 01:11:28,117
that began far back in time
and halfway around the world.

925
01:11:30,886 --> 01:11:33,889
SELLERS:
Ancient sediments laid down by other organisms

926
01:11:33,922 --> 01:11:37,126
millions of years ago
get eroded, make dust,

927
01:11:37,159 --> 01:11:39,295
the winds bring them
across the Atlantic,

928
01:11:39,328 --> 01:11:42,665
fertilize the tropical forest
in the Amazon.

929
01:11:53,642 --> 01:11:56,712
NARRATOR:
The migration of Bodele dust to the Amazon

930
01:11:56,745 --> 01:11:59,782
is just one of many ways
that vital minerals spread

931
01:11:59,815 --> 01:12:03,986
to living habitats
all over the world.

932
01:12:04,019 --> 01:12:07,222
Every landscape has
its own story

933
01:12:07,256 --> 01:12:10,959
and its own way of entering
the chain of life.

934
01:12:16,598 --> 01:12:19,768
BRISTOW:
The exchange of nutrients from the land

935
01:12:19,802 --> 01:12:23,105
is going on
all over the globe every day.

936
01:12:27,843 --> 01:12:30,546
NARRATOR:
And in certain areas, this is what accounts

937
01:12:30,579 --> 01:12:33,148
for the special productivity
of the soil.

938
01:12:37,219 --> 01:12:40,689
The Great Plains of North
America are rich in minerals

939
01:12:40,723 --> 01:12:43,125
eroded from the Rocky Mountains.

940
01:12:43,158 --> 01:12:47,363
These are vital ingredients
for growing wheat and corn.

941
01:12:52,000 --> 01:12:56,405
In Bangladesh, the Ganges delta
is rich in iron

942
01:12:56,438 --> 01:12:59,308
washed down from the Himalayas
in river sediments,

943
01:12:59,341 --> 01:13:03,011
ideal for growing rice.

944
01:13:04,913 --> 01:13:08,817
The hidden transport of minerals
creates fertile soils

945
01:13:08,851 --> 01:13:11,253
that enable plants to thrive.

946
01:13:11,286 --> 01:13:13,889
These minerals are the basis
of the food chain

947
01:13:13,922 --> 01:13:18,494
for all life on land,
including us.

948
01:13:18,527 --> 01:13:19,762
SELLERS:
All of this reminds you

949
01:13:19,795 --> 01:13:23,699
how interconnected
the earth system is...

950
01:13:26,835 --> 01:13:30,773
...that no living thing lives
in isolation from processes

951
01:13:30,806 --> 01:13:33,242
that may happen a long way away

952
01:13:33,275 --> 01:13:36,245
in both space and time
from itself.

953
01:13:40,015 --> 01:13:43,152
NARRATOR:
Satellites provide a vivid new perspective on the links

954
01:13:43,185 --> 01:13:48,957
between land, sea,
air and life.

955
01:13:48,991 --> 01:13:51,593
This new perspective
helps us see

956
01:13:51,627 --> 01:13:54,997
how the natural forces
of our planet fit together,

957
01:13:55,030 --> 01:13:57,766
and that includes the atmosphere

958
01:13:57,800 --> 01:14:01,670
and something as basic
as the air we breathe.

959
01:14:05,808 --> 01:14:08,110
Less than a quarter
of the air around us

960
01:14:08,143 --> 01:14:14,416
is comprised of oxygen, but that
oxygen is essential to life.

961
01:14:14,450 --> 01:14:19,087
It's what all animals need
to burn fuel in their bodies.

962
01:14:20,923 --> 01:14:24,726
Oxygen is vital to metabolism.

963
01:14:24,760 --> 01:14:26,261
It provides the energy

964
01:14:26,295 --> 01:14:29,298
that allows ev the most active
creatures to survive and thrive

965
01:14:29,331 --> 01:14:31,500
and to master
their environments.

966
01:14:36,472 --> 01:14:38,907
Scientists believe
that the abundance of oxygen

967
01:14:38,941 --> 01:14:42,478
in the atmosphere was essential
for the evolution of large,

968
01:14:42,511 --> 01:14:44,813
intelligent mammals like us.

969
01:14:44,847 --> 01:14:50,986
The human brain alone uses about
20% of the oxygen we breathe.

970
01:14:51,019 --> 01:14:55,824
But where does
all this oxygen come from?

971
01:14:55,858 --> 01:14:59,661
Satellites can help us answer
that question.

972
01:15:02,998 --> 01:15:06,768
NASA's <i>Aura</i> satellite
is one of several spacecraft

973
01:15:06,802 --> 01:15:12,274
that are helping scientists
study the earth's atmosphere.

974
01:15:12,307 --> 01:15:14,443
Along with ground instruments,

975
01:15:14,476 --> 01:15:20,549
it can analyze the atmosphere
and pinpoint its composition.

976
01:15:20,582 --> 01:15:22,851
It builds a picture
of the nitrogen,

977
01:15:22,885 --> 01:15:25,254
oxygen and carbon dioxide

978
01:15:25,287 --> 01:15:29,892
that together make up 99%
of the air we breathe.

979
01:15:37,833 --> 01:15:40,469
This computer
visualization shows

980
01:15:40,502 --> 01:15:45,107
how the earth's atmosphere
changes over 24 hours.

981
01:15:45,140 --> 01:15:48,744
During the day, oxygen--
seen here in blue--

982
01:15:48,777 --> 01:15:53,248
rises all over the planet.

983
01:15:53,282 --> 01:15:57,085
At night, carbon dioxide--
shown in orange--

984
01:15:57,119 --> 01:15:58,921
is on the rise.

985
01:15:58,954 --> 01:16:03,659
And the oxygen we need
is given to us by plants.

986
01:16:06,562 --> 01:16:09,631
Before plants, there was
no oxygen in the atmosphere.

987
01:16:09,665 --> 01:16:11,700
So plants did all the hard work

988
01:16:11,733 --> 01:16:13,368
of allowing the atmospheric
concentration

989
01:16:13,402 --> 01:16:17,673
to build up over time, allowing
all other life to develop.

990
01:16:17,706 --> 01:16:21,109
They made the place habitable
for us.

991
01:16:21,143 --> 01:16:26,148
NARRATOR:
Plants breathe in carbon dioxide and expel oxygen.

992
01:16:26,181 --> 01:16:29,685
They produce so much
that the vast Amazon rainforest

993
01:16:29,718 --> 01:16:33,255
is often called the lungs
of the earth.

994
01:16:33,288 --> 01:16:35,924
But the real picture
is more complex.

995
01:16:46,001 --> 01:16:48,437
The verdant wilderness
of plants and animals

996
01:16:48,470 --> 01:16:51,873
is one of the oldest,
most abundant living systems

997
01:16:51,907 --> 01:16:53,175
on earth.

998
01:16:55,978 --> 01:16:59,581
Over two million square miles
of lush rainforest

999
01:16:59,615 --> 01:17:03,785
teem with half the world's
living species.

1000
01:17:08,924 --> 01:17:10,258
SELLERS:
The Amazon is

1001
01:17:10,292 --> 01:17:16,098
the largest natural preserve
of life on the continents

1002
01:17:16,131 --> 01:17:17,265
that's left in the world.

1003
01:17:18,967 --> 01:17:23,372
Thousands of miles
of almost virgin forest,

1004
01:17:23,405 --> 01:17:25,507
thousands of species
that have been there

1005
01:17:25,540 --> 01:17:28,510
for an awfully long time.

1006
01:17:28,543 --> 01:17:33,849
NARRATOR:
So dense is the Amazon jungle that it has a dramatic impact

1007
01:17:33,882 --> 01:17:36,351
on the air above it.

1008
01:17:36,385 --> 01:17:41,423
It starts in the trillions
of leaves far below.

1009
01:17:46,261 --> 01:17:49,898
We can use animation to show
what this invisible process,

1010
01:17:49,931 --> 01:17:52,968
known as photosynthesis,
might look like.

1011
01:17:56,071 --> 01:18:00,409
During the day, the leaf takes
up carbon dioxide from the air,

1012
01:18:00,442 --> 01:18:04,346
seen here in orange.

1013
01:18:04,379 --> 01:18:08,417
It converts the carbon
into sugar for energy and growth

1014
01:18:08,450 --> 01:18:11,887
and releases oxygen,
seen in blue.

1015
01:18:31,339 --> 01:18:33,341
Each one of these trees
will release

1016
01:18:33,375 --> 01:18:36,578
hundreds of thousands of cubic
meters of oxygen

1017
01:18:36,611 --> 01:18:38,447
in the course of its life.

1018
01:18:42,784 --> 01:18:45,120
And as for the Amazon
as a whole,

1019
01:18:45,153 --> 01:18:49,458
a fifth of the world's oxygen
is produced here.

1020
01:18:50,959 --> 01:18:54,329
But there's a surprising twist:

1021
01:18:54,362 --> 01:18:57,866
we will breathe
almost none of it.

1022
01:19:05,640 --> 01:19:08,443
Satellite data and ground
measurements reveal

1023
01:19:08,477 --> 01:19:12,547
that almost all the oxygen the
Amazon produces during the day

1024
01:19:12,581 --> 01:19:18,720
remains there and is reabsorbed
into the forest at night.

1025
01:19:18,754 --> 01:19:21,022
SELLERS:
With the advantage of the satellites,

1026
01:19:21,056 --> 01:19:22,724
we can now see that the Amazon

1027
01:19:22,758 --> 01:19:25,127
basically uses
all its own oxygen

1028
01:19:25,160 --> 01:19:27,095
and uses all its own
carbon dioxide.

1029
01:19:27,129 --> 01:19:30,599
It is, as far as we can tell,

1030
01:19:30,632 --> 01:19:33,368
almost a closed system
in itself-- almost.

1031
01:19:37,072 --> 01:19:39,608
NARRATOR:
But the Amazon still plays a vital part

1032
01:19:39,641 --> 01:19:43,912
in generating the oxygen
that we breathe.

1033
01:19:45,680 --> 01:19:48,416
What satellites
now make clear is

1034
01:19:48,450 --> 01:19:52,721
producing the oxygen that
benefits us takes an extra step.

1035
01:19:55,323 --> 01:19:57,926
The process begins with rain,

1036
01:19:57,959 --> 01:20:03,198
which falls up to 250 days
a year in the Amazon.

1037
01:20:03,231 --> 01:20:04,699
The soil of the rainforest

1038
01:20:04,733 --> 01:20:08,270
is continually washed
into the Amazon river system,

1039
01:20:08,303 --> 01:20:11,873
taking with it nutrients
and organic material.

1040
01:20:11,907 --> 01:20:16,745
An average of two million tons
of this sediment

1041
01:20:16,778 --> 01:20:20,282
is released every 24 hours.

1042
01:20:20,315 --> 01:20:22,851
The sediment flows eastward,

1043
01:20:22,884 --> 01:20:26,655
traveling 4,000 miles
into the Amazon delta.

1044
01:20:29,925 --> 01:20:34,229
Here, microscopic plankton
near the surface thrive

1045
01:20:34,262 --> 01:20:37,499
on the nutrients and
their population explodes.

1046
01:20:39,367 --> 01:20:41,536
As they spread further
out to sea,

1047
01:20:41,570 --> 01:20:45,207
some of these tiny organisms
act like plants,

1048
01:20:45,240 --> 01:20:49,311
absorbing carbon dioxide
and releasing oxygen.

1049
01:20:53,748 --> 01:20:58,286
Again the <i>Aqua</i> satellite shows
us how a giant plankton bloom

1050
01:20:58,320 --> 01:21:03,158
grows to cover 25,000
square miles.

1051
01:21:06,361 --> 01:21:12,601
This vast area translates into a
huge boom in oxygen production,

1052
01:21:12,634 --> 01:21:15,971
made available
to the entire planet.

1053
01:21:21,877 --> 01:21:25,180
FELDMAN:
When plankton grow, they release oxygen.

1054
01:21:25,213 --> 01:21:28,550
That oxygen ultimately finds
its way into the atmosphere.

1055
01:21:31,553 --> 01:21:34,055
NARRATOR:
The massive scale of this impact

1056
01:21:34,089 --> 01:21:37,626
is revealed when the satellite
data is visualized.

1057
01:21:44,766 --> 01:21:48,970
This animation shows the oxygen
produced by plankton blooms,

1058
01:21:49,004 --> 01:21:52,540
seen here in bright blue.

1059
01:21:52,574 --> 01:21:56,278
The Amazon plankton bloom
releases billions of gallons

1060
01:21:56,311 --> 01:21:59,180
of oxygen into the atmosphere
every day.

1061
01:21:59,214 --> 01:22:02,183
Within a few days
the plankton die,

1062
01:22:02,217 --> 01:22:05,887
leaving most of the oxygen
they produced in the air

1063
01:22:05,921 --> 01:22:08,456
as they sink to the bottom
of the ocean.

1064
01:22:14,930 --> 01:22:17,565
Similar explosions
of microscopic life

1065
01:22:17,599 --> 01:22:19,768
happen all over the world.

1066
01:22:19,801 --> 01:22:23,705
Plankton's major role
in replenishing oxygen

1067
01:22:23,738 --> 01:22:27,275
in the atmosphere is something
we've only fully grasped

1068
01:22:27,309 --> 01:22:29,411
with the help of satellites.

1069
01:22:36,151 --> 01:22:37,552
FELDMAN:
Satellites gave us

1070
01:22:37,585 --> 01:22:39,888
that very first global picture,

1071
01:22:39,921 --> 01:22:47,662
global assessment of what
the ocean's plants were doing.

1072
01:22:47,696 --> 01:22:52,000
NARRATOR:
And what plankton are doing is providing life-giving oxygen

1073
01:22:52,033 --> 01:22:53,601
for us.

1074
01:22:59,641 --> 01:23:02,610
FELDMAN:
Plankton in the ocean are responsible for over half

1075
01:23:02,644 --> 01:23:06,281
of the oxygen that we breathe,

1076
01:23:06,314 --> 01:23:09,317
and it's what most creatures on
this planet rely on to survive.

1077
01:23:11,820 --> 01:23:15,824
NARRATOR:
Microscopic organisms as well as rainforests

1078
01:23:15,857 --> 01:23:18,093
are the lungs of the earth.

1079
01:23:26,334 --> 01:23:29,671
So what other secrets of life
can satellites--

1080
01:23:29,704 --> 01:23:32,007
our eyes in space-- reveal?

1081
01:23:34,042 --> 01:23:38,146
It turns out that another
surprising way life is sustained

1082
01:23:38,179 --> 01:23:41,950
is through a violent force:
lightning.

1083
01:23:51,960 --> 01:23:57,799
From orbit, the whole earth
buzzes with electricity.

1084
01:23:59,067 --> 01:24:01,903
Astronauts are often amazed
by the intensity

1085
01:24:01,936 --> 01:24:06,207
of the electrical storms raging
far beneath them.

1086
01:24:08,209 --> 01:24:10,578
SELLERS:
You can see a thousand miles' worth

1087
01:24:10,612 --> 01:24:18,053
of lightning flashes left and
right as you're looking down,

1088
01:24:18,086 --> 01:24:19,721
and they seem to set each other
off like fireworks,

1089
01:24:19,754 --> 01:24:20,755
bang, bang, bang, bang, bang.

1090
01:24:20,789 --> 01:24:23,825
It's really quite amazing.

1091
01:24:25,393 --> 01:24:28,563
NARRATOR:
But to understand lightning's global impact,

1092
01:24:28,596 --> 01:24:30,598
we need more than just
observation.

1093
01:24:37,872 --> 01:24:41,376
NASA's TRMM satellite carries
a high-speed camera

1094
01:24:41,409 --> 01:24:45,013
that can detect individual
lightning bolts.

1095
01:24:48,817 --> 01:24:52,854
From this information it's
possible to build a picture

1096
01:24:52,887 --> 01:24:57,058
showing the distribution of
lightning all across the globe.

1097
01:25:04,566 --> 01:25:09,704
Astonishingly, 40 strikes occur
every second.

1098
01:25:13,074 --> 01:25:18,213
That's more than three million
strikes a day.

1099
01:25:18,246 --> 01:25:21,382
So how is all this lightning
created?

1100
01:25:21,416 --> 01:25:24,652
And what is the effect
of all this energy

1101
01:25:24,686 --> 01:25:27,622
streaking through
the earth's atmosphere?

1102
01:25:33,294 --> 01:25:36,631
Each day, the combined force
of sunlight and water vapor

1103
01:25:36,664 --> 01:25:42,103
creates 40,000 thunderclouds.

1104
01:25:42,137 --> 01:25:45,840
The rising columns of moist air
generate powerful updrafts

1105
01:25:45,874 --> 01:25:48,510
that turn water vapor
into ice particles

1106
01:25:48,543 --> 01:25:50,111
inside the clouds.

1107
01:25:52,547 --> 01:25:57,385
As ice and water droplets smash
into each other at great speed,

1108
01:25:57,418 --> 01:26:01,589
vast charges of static
electricity build up.

1109
01:26:09,164 --> 01:26:12,200
An average thundercloud contains
enough energy

1110
01:26:12,233 --> 01:26:17,472
to power a city the size
of Denver for ten hours.

1111
01:26:20,675 --> 01:26:23,311
Eventually the charge builds
to a point

1112
01:26:23,344 --> 01:26:26,548
where air molecules
are torn apart

1113
01:26:26,581 --> 01:26:28,650
and a lightning bolt is born.

1114
01:26:34,856 --> 01:26:38,293
A bolt is no thicker
than a human thumb,

1115
01:26:38,326 --> 01:26:40,728
yet it's five times
the temperature

1116
01:26:40,762 --> 01:26:43,431
of the surface of the sun.

1117
01:26:43,464 --> 01:26:45,800
As it burns through
the atmosphere,

1118
01:26:45,833 --> 01:26:49,337
the electricity breaks apart
the molecules of nitrogen

1119
01:26:49,370 --> 01:26:51,072
contained in the air.

1120
01:26:52,907 --> 01:26:54,008
ADAMEC:
A lightning stroke,

1121
01:26:54,042 --> 01:26:56,711
it actually splits the nitrogen

1122
01:26:56,744 --> 01:26:59,314
into single nitrogen molecules.

1123
01:27:02,116 --> 01:27:03,518
Nitrogen doesn't like that.

1124
01:27:03,551 --> 01:27:05,119
It's desperately looking
for something

1125
01:27:05,153 --> 01:27:08,423
to connect back to with and it
often does it with oxygen.

1126
01:27:11,192 --> 01:27:13,962
NARRATOR:
When oxygen bonds with nitrogen,

1127
01:27:13,995 --> 01:27:18,433
it creates a vital nutrient
called nitrate.

1128
01:27:27,575 --> 01:27:30,178
Satellites show the extent
of nitrate--

1129
01:27:30,211 --> 01:27:31,980
simulated here in yellow--

1130
01:27:32,013 --> 01:27:34,716
produced by the more than three
million lightning bolts

1131
01:27:34,749 --> 01:27:37,852
that strike every day.

1132
01:27:37,885 --> 01:27:43,858
This creates about 13,000 tons
of nitrate.

1133
01:27:43,891 --> 01:27:46,728
It dissolves in water droplets
in the clouds

1134
01:27:46,761 --> 01:27:50,531
and falls to the ground in rain.

1135
01:28:01,976 --> 01:28:03,378
Most people are familiar
with nitrates

1136
01:28:03,411 --> 01:28:04,545
because they're fertilizers.

1137
01:28:05,913 --> 01:28:08,750
So when it rains
in a thunderstorm,

1138
01:28:08,783 --> 01:28:11,152
in a way you're getting a free
fertilizing,

1139
01:28:11,185 --> 01:28:12,887
because the water will have
nitrates in it.

1140
01:28:15,423 --> 01:28:18,192
NARRATOR:
Nitrate is absorbed through the roots of plants

1141
01:28:18,226 --> 01:28:19,727
and enters the food chain.

1142
01:28:19,761 --> 01:28:24,966
When we eat these plants, the
nitrates become available to us.

1143
01:28:27,602 --> 01:28:29,837
And so this vital nutrient
enters the cells

1144
01:28:29,871 --> 01:28:32,607
of every living organism
on earth,

1145
01:28:32,640 --> 01:28:37,812
where it is critical for
building the structure of plants

1146
01:28:37,845 --> 01:28:41,816
and helps make proteins and DNA
in our bodies as well.

1147
01:28:44,619 --> 01:28:49,490
It is essential for the survival
of all living things.

1148
01:29:03,204 --> 01:29:05,640
But nitrate production
is not the only way

1149
01:29:05,673 --> 01:29:08,409
in which lightning
promotes life on earth.

1150
01:29:14,415 --> 01:29:16,417
In the Canadian Yukon,

1151
01:29:16,451 --> 01:29:20,521
a massive wildfire devastates
over ten square miles of forest

1152
01:29:20,555 --> 01:29:21,823
in less than a week.

1153
01:29:29,097 --> 01:29:32,633
Such blazes often start with
a random bolt of electricity

1154
01:29:32,667 --> 01:29:33,935
from the sky.

1155
01:29:43,878 --> 01:29:48,683
In distant Siberia, over 1,500
square miles of forest

1156
01:29:48,716 --> 01:29:51,652
burn to the ground,
sparked by a lightning bolt.

1157
01:30:04,966 --> 01:30:08,770
These flames may seem
purely destructive,

1158
01:30:08,803 --> 01:30:11,305
but thanks in part
to satellites,

1159
01:30:11,339 --> 01:30:15,376
we see that they can
also be life-giving.

1160
01:30:22,083 --> 01:30:25,720
The <i>Terra</i> satellite can detect
the location of every fire

1161
01:30:25,753 --> 01:30:33,027
on earth by looking at its heat
signature in infrared.

1162
01:30:33,060 --> 01:30:37,398
SELLERS:
<i>Terra</i> basically gives us a map of all the fires

1163
01:30:37,432 --> 01:30:41,302
in all the forests and
grasslands of the world

1164
01:30:41,335 --> 01:30:42,470
every day.

1165
01:30:45,706 --> 01:30:48,976
NARRATOR:
This sped-up visualization of <i>Terra's</i> data

1166
01:30:49,010 --> 01:30:52,647
shows a year's worth of fire
all around the world.

1167
01:30:54,715 --> 01:31:00,688
The vast swaths of orange are
actually thousds of tiny dots.

1168
01:31:00,721 --> 01:31:04,759
Each one represents
a half square mile of land

1169
01:31:04,792 --> 01:31:07,395
where a fire has burned,

1170
01:31:07,428 --> 01:31:12,233
over 19 million square miles
in total.

1171
01:31:12,266 --> 01:31:17,038
The <i>Terra</i> data also reveal
fire's role in renewing life.

1172
01:31:20,608 --> 01:31:22,076
SELLERS:
The observations have shown us

1173
01:31:22,109 --> 01:31:25,112
how important fire is
as an element of change.

1174
01:31:27,648 --> 01:31:30,017
NARRATOR:
The benefits of change can be witnessed

1175
01:31:30,051 --> 01:31:34,922
in the forests
of northern Canada.

1176
01:31:38,392 --> 01:31:40,661
This is a vibrant forest,

1177
01:31:40,695 --> 01:31:44,832
but it has its share of dead
and diseased trees.

1178
01:31:47,802 --> 01:31:51,572
Locked inside them are
ingredients that are essential

1179
01:31:51,606 --> 01:31:58,145
for new life: elements like
carbon, sulfur and phosphorous.

1180
01:31:58,179 --> 01:32:01,616
Yet in a cold environment
like this,

1181
01:32:01,649 --> 01:32:05,052
trees take decades to decompose

1182
01:32:05,086 --> 01:32:09,023
and return these elements
back to the soil.

1183
01:32:11,092 --> 01:32:15,563
Fire can shorten the cycle
to a matter of hours.

1184
01:32:26,107 --> 01:32:31,178
The pine tree
is highly flammable.

1185
01:32:31,212 --> 01:32:35,850
It's full of sap and resins
that burn easily.

1186
01:32:35,883 --> 01:32:39,754
The oxygen in the atmosphere
fuels the flames.

1187
01:32:46,060 --> 01:32:47,361
ADAMEC:
When you're looking at fire,

1188
01:32:47,395 --> 01:32:49,597
you're looking at
a rapid oxidation.

1189
01:32:49,630 --> 01:32:50,665
That's what fire is.

1190
01:32:52,733 --> 01:32:54,569
NARRATOR:
Within a matter of hours,

1191
01:32:54,602 --> 01:32:57,872
what may have started as a spark
from a single lightning bolt

1192
01:32:57,905 --> 01:33:01,776
turns acres of forest to flames.

1193
01:33:06,547 --> 01:33:10,251
The nutrients these trees
have stored for so long

1194
01:33:10,284 --> 01:33:13,955
end up in the ash.

1195
01:33:17,391 --> 01:33:20,261
Fires also consume
the dead animals

1196
01:33:20,294 --> 01:33:22,863
whose bodies litter the forest,

1197
01:33:22,897 --> 01:33:27,201
returning the nutrients they
contain back to the soil.

1198
01:33:27,234 --> 01:33:30,705
The smoke climbs into the sky,

1199
01:33:30,738 --> 01:33:32,840
and the ultimate impact
of this nutrient-rich ash

1200
01:33:32,873 --> 01:33:37,278
can eventually be seen
from space.

1201
01:33:41,916 --> 01:33:43,851
With its infrared sensor,

1202
01:33:43,884 --> 01:33:47,188
<i>Terra</i> can pick out the heat
given off by the leaves

1203
01:33:47,221 --> 01:33:51,092
of healthy new vegetation
that grows after fire.

1204
01:33:54,528 --> 01:33:58,666
A pulse of new growth
follows every blaze.

1205
01:34:02,737 --> 01:34:04,972
Huge areas of forest get burned
down quite regularly

1206
01:34:05,006 --> 01:34:09,310
and they're followed almost
immediately by rapid regrowths.

1207
01:34:12,413 --> 01:34:14,649
NARRATOR:
In forests all over the world,

1208
01:34:14,682 --> 01:34:18,319
the data from <i>Aqua</i> and <i>Terra</i>
show that within months,

1209
01:34:18,352 --> 01:34:23,491
large areas devastated
by fire are rejuvenated.

1210
01:34:24,792 --> 01:34:26,894
From a global perspective,

1211
01:34:26,927 --> 01:34:30,231
wildfires are essential
to the cycle of life.

1212
01:34:37,805 --> 01:34:40,741
Fire's like a great blender
for all the materials

1213
01:34:40,775 --> 01:34:44,412
in the earth system, so when you
get dead living material,

1214
01:34:44,445 --> 01:34:45,713
particularly in the forests,

1215
01:34:45,746 --> 01:34:50,284
fire will rip through there
and decompose that stuff

1216
01:34:50,317 --> 01:34:53,654
very quickly into its basic
minerals and compounds

1217
01:34:53,688 --> 01:34:57,625
that new life can use
almost immediately.

1218
01:34:57,658 --> 01:35:01,228
NARRATOR:
Fire is such an intrinsic part of nature

1219
01:35:01,262 --> 01:35:06,367
that many plants have evolved
to make active use of it.

1220
01:35:09,103 --> 01:35:13,040
The pine tree drops its seeds in
the ashen aftermath of a blaze

1221
01:35:13,074 --> 01:35:15,209
to make the most
of the nutrients

1222
01:35:15,242 --> 01:35:16,310
that have been released.

1223
01:35:20,081 --> 01:35:22,717
Wildfires are essential
to maintaining the health

1224
01:35:22,750 --> 01:35:25,986
of many of the world's
ecosystems.

1225
01:35:26,020 --> 01:35:27,521
It's a mechanism by which

1226
01:35:27,555 --> 01:35:31,392
habitats that are no longer
productive regenerate.

1227
01:35:31,425 --> 01:35:34,995
We can now follow this process
over decades.

1228
01:35:37,264 --> 01:35:40,067
SELLERS:
When you look 30 years of satellite data,

1229
01:35:40,101 --> 01:35:43,838
you see this continuous, dynamic
rearrangement of the biosphere.

1230
01:35:43,871 --> 01:35:46,574
The nutrients that that tree
has pulled up from the soil

1231
01:35:46,607 --> 01:35:48,509
are being dropped back down
again on the soil

1232
01:35:48,542 --> 01:35:49,810
to feed the next generation.

1233
01:35:51,145 --> 01:35:53,280
The effect of all this is
to allow the biosphere

1234
01:35:53,314 --> 01:35:56,117
to turn over far more quickly
and efficiently.

1235
01:36:05,126 --> 01:36:07,561
NARRATOR:
By looking at the world from orbit,

1236
01:36:07,595 --> 01:36:10,664
we see our home planet anew.

1237
01:36:10,698 --> 01:36:16,203
We discover countless hidden
connections, all linked to life.

1238
01:36:16,237 --> 01:36:19,206
The circulation of weather
and ocean currents

1239
01:36:19,240 --> 01:36:22,143
affects the ebb and flow of ice
at the poles.

1240
01:36:30,217 --> 01:36:32,453
Originating
in the earth's crust,

1241
01:36:32,486 --> 01:36:36,791
erupting magma interacts
with cold ocean water,

1242
01:36:36,824 --> 01:36:39,660
producing nutrients that rise
to the surface

1243
01:36:39,693 --> 01:36:43,531
and nourish aquatic life.

1244
01:36:43,564 --> 01:36:45,466
Eventually, airborne in dust,

1245
01:36:45,499 --> 01:36:47,868
nutrients travel
around the planet,

1246
01:36:47,902 --> 01:36:53,374
finally enabling tiny plankton
to fill the air with oxygen.

1247
01:36:53,407 --> 01:36:57,378
That allows complex animals
like us to survive.

1248
01:37:00,114 --> 01:37:03,350
Oxygen also allows fire to burn,

1249
01:37:03,384 --> 01:37:07,454
which, in turn, accelerates
the pace of death and rebirth

1250
01:37:07,488 --> 01:37:09,123
in the forest.

1251
01:37:16,997 --> 01:37:20,234
Above all, life's major driver

1252
01:37:20,267 --> 01:37:24,505
is the energy we receive
from the sun.

1253
01:37:26,874 --> 01:37:30,678
As the earth rotates
over 24 hours,

1254
01:37:30,711 --> 01:37:34,481
the planet responds to the
incredible power of the sun,

1255
01:37:34,515 --> 01:37:36,750
our local star.

1256
01:37:40,054 --> 01:37:41,956
Each day more than
a million terawatts--

1257
01:37:41,989 --> 01:37:45,860
over 7,000 times our global
energy consumption--

1258
01:37:45,893 --> 01:37:48,062
strike earth.

1259
01:37:49,296 --> 01:37:54,168
This triggers a wave of activity
around the globe.

1260
01:37:55,502 --> 01:37:59,406
At dawn, plants on land
and plankton at sea

1261
01:37:59,440 --> 01:38:02,076
begin to photosynthesize
and grow.

1262
01:38:05,646 --> 01:38:06,947
At the same time,

1263
01:38:06,981 --> 01:38:10,084
sunlight drives wind and weather
around the globe.

1264
01:38:13,787 --> 01:38:16,991
We are also a part
of this cycle,

1265
01:38:17,024 --> 01:38:18,926
as our bodies respond

1266
01:38:18,959 --> 01:38:22,129
to the daily inflow of energy
from above.

1267
01:38:25,399 --> 01:38:31,705
Our skin cells use sunlight
to create essential vitamins.

1268
01:38:31,739 --> 01:38:35,876
Even the flight paths of planes
reveal our intimate relationship

1269
01:38:35,910 --> 01:38:38,445
with the rhythms
of day and night.

1270
01:38:38,479 --> 01:38:42,816
Aircraft travel west in
the morning to extend the day

1271
01:38:42,850 --> 01:38:47,755
and east in the evening
to reduce the night.

1272
01:38:50,457 --> 01:38:53,827
But while the sun nurtures
all life on earth,

1273
01:38:53,861 --> 01:38:56,330
it also has the power
to destroy.

1274
01:38:59,433 --> 01:39:01,869
And with the help of a very
different kind of satellite,

1275
01:39:01,902 --> 01:39:08,142
we are coming to understand just
how great a threat it can pose.

1276
01:39:13,280 --> 01:39:15,883
Orbiting 22,000 miles
above the earth

1277
01:39:15,916 --> 01:39:19,053
is the Solar Dynamics
Observatory.

1278
01:39:19,086 --> 01:39:24,692
This satellite looks not at
the earth, but away from it.

1279
01:39:24,725 --> 01:39:29,897
Its task is to observe the
radiation released by the sun--

1280
01:39:29,930 --> 01:39:33,167
what scientists call
space weather.

1281
01:39:36,403 --> 01:39:37,938
We have this wonderful
new satellite

1282
01:39:37,972 --> 01:39:42,176
that is up in space, looking
at the sun 24 hours a day

1283
01:39:42,209 --> 01:39:45,980
and is providing unprecedented
images of the sun

1284
01:39:46,013 --> 01:39:48,382
and where space weather is born.

1285
01:39:53,087 --> 01:39:55,255
NARRATOR:
These striking images are produced

1286
01:39:55,289 --> 01:39:58,125
by the SDO's ultraviolet sensor,

1287
01:39:58,158 --> 01:40:01,829
detecting light frequencies
beyond the blue end

1288
01:40:01,862 --> 01:40:03,430
of the visible spectrum.

1289
01:40:03,464 --> 01:40:07,301
The sun emits constant light,

1290
01:40:07,334 --> 01:40:11,205
heat and other forms
of radiation,

1291
01:40:11,238 --> 01:40:16,343
along with occasional dangerous
bursts of charged particles.

1292
01:40:23,083 --> 01:40:24,718
GILBERT:
Most people don't realize

1293
01:40:24,752 --> 01:40:27,021
that the earth is exposed
to charged particles

1294
01:40:27,054 --> 01:40:28,922
that are constantly coming away
from the sun

1295
01:40:28,956 --> 01:40:31,158
at about a million miles
an hour.

1296
01:40:32,993 --> 01:40:36,330
NARRATOR:
Sometimes a massive pulse of those charged particles

1297
01:40:36,363 --> 01:40:39,033
erupts from the sun's surface.

1298
01:40:39,066 --> 01:40:42,803
It's called
a coronal mass ejection

1299
01:40:42,836 --> 01:40:46,206
and it contains billions of tons
of charged particles

1300
01:40:46,240 --> 01:40:50,277
superheated to tens of millions
of degrees

1301
01:40:50,310 --> 01:40:56,083
and blasted out at millions
of miles per hour.

1302
01:40:56,116 --> 01:41:00,454
It has the potential to wreak
havoc on our planet.

1303
01:41:03,891 --> 01:41:07,795
This supercomputer visualization
shows what happens

1304
01:41:07,828 --> 01:41:11,298
when a coronal mass ejection
occurs.

1305
01:41:13,300 --> 01:41:19,406
The explosion is equivalent
to 14 million Hiroshima bombs.

1306
01:41:20,941 --> 01:41:25,913
It sends a cloud of charged
particles millions of miles wide

1307
01:41:25,946 --> 01:41:28,415
racing towards earth.

1308
01:41:30,017 --> 01:41:32,119
Without some kind of protection,

1309
01:41:32,152 --> 01:41:37,291
these enormous blasts would
strip away the atmosphere,

1310
01:41:37,324 --> 01:41:43,864
destroy our fragile ecosystems
and scorch the earth.

1311
01:41:43,897 --> 01:41:48,702
Over time, repeated coronal mass
ejections would even cause

1312
01:41:48,735 --> 01:41:51,905
the oceans to dry up,

1313
01:41:51,939 --> 01:41:57,111
leaving behind a planet
as barren and bleak as Mars.

1314
01:41:57,144 --> 01:42:01,882
Fortunately the earth has
an invisible shield,

1315
01:42:01,915 --> 01:42:04,751
a magnetic field that satellites
are now enabling us

1316
01:42:04,785 --> 01:42:07,888
to better understand.

1317
01:42:07,921 --> 01:42:13,293
Orbiting between 40,000 and
120,000 miles above the earth,

1318
01:42:13,327 --> 01:42:17,865
NASA has a network of satellites
called THEMIS.

1319
01:42:17,898 --> 01:42:21,201
Each is equipped with highly
sensitive instruments

1320
01:42:21,235 --> 01:42:25,472
that can detect the strength
of magnetic fields.

1321
01:42:25,506 --> 01:42:26,940
GILBERT:
THEMIS is a series

1322
01:42:26,974 --> 01:42:31,945
of probes that are aligned along
the earth's magnetosphere

1323
01:42:31,979 --> 01:42:36,216
and they detect variations
in the magnetic fields.

1324
01:42:36,250 --> 01:42:39,820
NARRATOR:
This computer model, using THEMIS data,

1325
01:42:39,853 --> 01:42:42,456
shows how an invisible
magnetic force field

1326
01:42:42,489 --> 01:42:45,993
called the magnetosphere
protects the earth.

1327
01:42:46,026 --> 01:42:49,429
It's generated by the rotation
of the earth's core.

1328
01:42:51,431 --> 01:42:54,968
GILBERT:
THEMIS allows us to build a overall picture

1329
01:42:55,002 --> 01:42:56,904
of the structure
of the magnetosphere

1330
01:42:56,937 --> 01:42:58,105
and how it operates.

1331
01:43:06,413 --> 01:43:08,615
NARRATOR:
THEMIS reveals how the magnetic field

1332
01:43:08,649 --> 01:43:10,984
is constantly blasted
by the sun.

1333
01:43:13,854 --> 01:43:18,025
The wave of charged particles
called the solar wind

1334
01:43:18,058 --> 01:43:23,030
distorts the magnetosphere into
a gigantic teardrop shape,

1335
01:43:23,063 --> 01:43:26,300
120,000 miles across.

1336
01:43:41,348 --> 01:43:44,151
As wave after wave
of solar particles

1337
01:43:44,184 --> 01:43:48,155
strike the outer magnetosphere,
most are deflected.

1338
01:43:52,993 --> 01:43:55,829
But when a coronal mass ejection
arrives,

1339
01:43:55,862 --> 01:43:58,632
it tears open the magnetosphere,

1340
01:43:58,665 --> 01:44:01,735
allowing a vast number
of charged particles

1341
01:44:01,768 --> 01:44:04,972
to breach the magnetic field's
first layer.

1342
01:44:12,079 --> 01:44:16,149
The particles are free to rush
in towards the planet.

1343
01:44:16,183 --> 01:44:20,220
But the earth has a second line
of defense.

1344
01:44:21,788 --> 01:44:24,791
Inner magnetic fields steer
the radiation

1345
01:44:24,825 --> 01:44:28,228
down towards the poles.

1346
01:44:28,262 --> 01:44:31,999
GILBERT:
This process is extremely energetic.

1347
01:44:32,032 --> 01:44:34,968
Particles get accelerated
and then they travel down

1348
01:44:35,002 --> 01:44:38,572
along the magnetic field lines
towards the polar regions.

1349
01:44:41,008 --> 01:44:44,411
NARRATOR:
The radiation streams downward,

1350
01:44:44,444 --> 01:44:48,248
encircling both
the North and South poles,

1351
01:44:48,282 --> 01:44:51,785
and triggers something we can
see with our own eyes,

1352
01:44:51,818 --> 01:44:54,688
one of nature's true wonders:

1353
01:44:54,721 --> 01:44:58,125
the Northern and Southern
lights, or the aurora.

1354
01:45:07,034 --> 01:45:10,003
As the radiation strikes
the upper atmosphere

1355
01:45:10,037 --> 01:45:14,508
at extreme speed, it excites
the air molecules.

1356
01:45:14,541 --> 01:45:17,210
This makes them glow.

1357
01:45:20,681 --> 01:45:25,052
The oxygen in the air radiates
red and green.

1358
01:45:25,085 --> 01:45:27,454
The nitrogen, red and blue.

1359
01:45:29,990 --> 01:45:31,925
These charged particles
that originated from the sun

1360
01:45:31,958 --> 01:45:34,061
get trapped and then
interact directly

1361
01:45:34,094 --> 01:45:37,431
with the earth's atmosphere,
causing these beautiful colors.

1362
01:45:37,464 --> 01:45:40,434
So when we're looking
at the aurora,

1363
01:45:40,467 --> 01:45:41,935
basically we're looking
at the fact

1364
01:45:41,968 --> 01:45:44,137
that the sun and the earth
are intimately connected.

1365
01:45:46,306 --> 01:45:49,076
NARRATOR:
The aurora is a vivid reminder

1366
01:45:49,109 --> 01:45:53,280
of how potentially lethal energy
from the sun is dissipated

1367
01:45:53,313 --> 01:45:54,848
in the upper atmosphere.

1368
01:45:57,918 --> 01:46:01,188
The earth's magnetic field has
shielded the planet

1369
01:46:01,221 --> 01:46:05,659
from the sun's deadly radiation
for billions of years,

1370
01:46:05,692 --> 01:46:09,529
enabling life to take hold
and flourish.

1371
01:46:14,835 --> 01:46:17,704
Satellites are revealing
one final piece

1372
01:46:17,738 --> 01:46:22,342
of this incredible puzzle--
the role that humanity plays.

1373
01:46:25,879 --> 01:46:28,915
Our human footprint
has grown so large

1374
01:46:28,949 --> 01:46:33,253
that we have become a major
global force in our own right.

1375
01:46:33,286 --> 01:46:36,256
Our impact is the consequence
of a system

1376
01:46:36,289 --> 01:46:38,792
that has created
and sustained life

1377
01:46:38,825 --> 01:46:42,195
for three and a half billion
years.

1378
01:46:45,966 --> 01:46:48,802
Our success as a species
has resulted

1379
01:46:48,835 --> 01:46:51,772
in rapid population growth.

1380
01:46:51,805 --> 01:46:54,107
And today our presence
can be seen

1381
01:46:54,141 --> 01:46:57,377
across 80% of the landmass.

1382
01:46:57,411 --> 01:47:01,782
Now we, in turn, are affecting
the many natural cycles

1383
01:47:01,815 --> 01:47:03,283
that govern our planet.

1384
01:47:07,354 --> 01:47:09,956
Looking for signs of pollution,

1385
01:47:09,990 --> 01:47:13,860
the environmental satellite
<i>Aura's</i> infrared sensor reveals

1386
01:47:13,894 --> 01:47:16,530
the atmosphere's chemical
fingerprint

1387
01:47:16,563 --> 01:47:21,568
and shows us how we are
affecting the entire globe.

1388
01:47:21,601 --> 01:47:25,005
We already manufacture more
than twice the nitrate produced

1389
01:47:25,038 --> 01:47:30,644
by lightning, much of it used
for fertilizer and explosives.

1390
01:47:30,677 --> 01:47:32,879
Our factories release
more sulfur

1391
01:47:32,913 --> 01:47:37,050
than all the earth's volcanoes.

1392
01:47:37,083 --> 01:47:41,154
Our industry and transportation
produce more carbon dioxide

1393
01:47:41,188 --> 01:47:45,192
than the Amazon rainforest
captures.

1394
01:47:45,225 --> 01:47:47,727
Our cities generate dust,

1395
01:47:47,761 --> 01:47:51,998
trigger electrical storms
and affect rainfall.

1396
01:47:52,032 --> 01:47:54,568
And these are just a few
of our impacts

1397
01:47:54,601 --> 01:47:56,703
on earth's natural cycles.

1398
01:48:02,509 --> 01:48:03,944
Our earth is changing.

1399
01:48:03,977 --> 01:48:06,046
We're on a path to somewhere

1400
01:48:06,079 --> 01:48:09,583
and our ability to understand
that path is crucial

1401
01:48:09,616 --> 01:48:12,052
to success in the future.

1402
01:48:12,085 --> 01:48:13,787
And satellites help us answer

1403
01:48:13,820 --> 01:48:16,523
some of the most fundamental
questions

1404
01:48:16,556 --> 01:48:19,860
needed to understand
how our planet behaves.

1405
01:48:24,731 --> 01:48:26,399
NARRATOR:
But there is one key difference

1406
01:48:26,433 --> 01:48:30,370
between the impact
of nature and our own.

1407
01:48:30,403 --> 01:48:34,541
Unlike volcanoes,
the motion of ocean currents,

1408
01:48:34,574 --> 01:48:38,411
or the oxygen produced by
forests and plankton blooms,

1409
01:48:38,445 --> 01:48:42,549
we make conscious decisions
about what we do.

1410
01:48:42,582 --> 01:48:46,086
And here satellites
are crucial once more.

1411
01:48:46,119 --> 01:48:49,055
The information they provide
can help us meet

1412
01:48:49,089 --> 01:48:51,691
the challenges of the future.

1413
01:49:01,968 --> 01:49:05,372
SELLERS:
The real power of satellite observations

1414
01:49:05,405 --> 01:49:07,340
is they represent
objective truth.

1415
01:49:07,374 --> 01:49:10,710
They tell us about what
the world actually is doing,

1416
01:49:10,744 --> 01:49:12,679
not what we would like it
to be doing,

1417
01:49:12,712 --> 01:49:14,314
not what we might fear it
to be doing,

1418
01:49:14,347 --> 01:49:15,982
but what it's actually doing.

1419
01:49:16,016 --> 01:49:19,719
And it's that that allows us
to see change,

1420
01:49:19,753 --> 01:49:21,421
real change, for what it is.

1421
01:49:27,127 --> 01:49:31,565
NARRATOR:
Satellites are telling us that the oceans are slowly warming.

1422
01:49:31,598 --> 01:49:33,633
In the past 30 years,

1423
01:49:33,667 --> 01:49:37,137
the average temperature
of the ocean's surface has risen

1424
01:49:37,170 --> 01:49:38,605
by half a degree.

1425
01:49:38,638 --> 01:49:42,609
Models suggest this extra heat

1426
01:49:42,642 --> 01:49:44,778
could be increasing the
intensity of hurricanes

1427
01:49:44,811 --> 01:49:47,514
and violent storms
all around the world.

1428
01:49:52,953 --> 01:49:56,089
Satellite data shows
that in Antarctica,

1429
01:49:56,122 --> 01:49:59,726
ice shelves that took many
thousands of years to form

1430
01:49:59,759 --> 01:50:02,996
are collapsing year after year.

1431
01:50:03,029 --> 01:50:08,668
And in the Arctic, sea ice is
diminishing at an alarming rate.

1432
01:50:08,702 --> 01:50:12,072
Many factors play a part
in these dramatic changes,

1433
01:50:12,105 --> 01:50:13,807
but most scientists agree

1434
01:50:13,840 --> 01:50:18,411
that human activity through
our release of greenhouse gases

1435
01:50:18,445 --> 01:50:20,981
is the main driving force.

1436
01:50:24,751 --> 01:50:28,355
All around the globe, satellites
are recording change,

1437
01:50:28,388 --> 01:50:30,323
but there is a problem.

1438
01:50:30,357 --> 01:50:34,427
Just as we are able to capture
and measure these changes,

1439
01:50:34,461 --> 01:50:36,830
many of the current fleet
of satellites

1440
01:50:36,863 --> 01:50:40,500
are coming to the end
of their lives.

1441
01:50:40,533 --> 01:50:44,738
Satellites need fuel
to stay in their orbits.

1442
01:50:44,771 --> 01:50:46,506
When their time is up,

1443
01:50:46,539 --> 01:50:49,843
they must either use the last of
their fuel to boost themselves

1444
01:50:49,876 --> 01:50:51,911
far away from the earth

1445
01:50:51,945 --> 01:50:55,382
or descend and burn up
on reentry.

1446
01:50:59,152 --> 01:51:01,054
It's predicted that the number

1447
01:51:01,087 --> 01:51:05,392
of NASA's earth-observing
satellite systems will go

1448
01:51:05,425 --> 01:51:09,796
from 20 down to fewer than ten
within the next decade.

1449
01:51:15,435 --> 01:51:18,405
The constant stream
of information

1450
01:51:18,438 --> 01:51:22,742
from these vital instruments
in space will fade.

1451
01:51:22,776 --> 01:51:25,478
If we fail to replace
these satellites,

1452
01:51:25,512 --> 01:51:29,015
we could lose our ability to
track the web of connections

1453
01:51:29,049 --> 01:51:31,484
that is fundamental to life.

1454
01:51:34,287 --> 01:51:42,662
ADAMEC:
The complex interactions would be absolutely invisible to us

1455
01:51:42,696 --> 01:51:46,633
without a larger view
of the earth.

1456
01:51:46,666 --> 01:51:50,804
It's the consistency and the
amount of data that they provide

1457
01:51:50,837 --> 01:51:53,773
that allows us to understand
the processes that are going on

1458
01:51:53,807 --> 01:51:56,042
in the earth that are important
to maintaining life

1459
01:51:56,076 --> 01:51:57,143
as we know it.

1460
01:51:59,779 --> 01:52:01,715
NARRATOR:
Little more than half a century

1461
01:52:01,748 --> 01:52:04,584
after the birth
of satellite technology,

1462
01:52:04,617 --> 01:52:08,922
we are still only beginning
to realize its possibilities.

1463
01:52:08,955 --> 01:52:12,659
Our planet harbors mysteries
beneath its white clouds,

1464
01:52:12,692 --> 01:52:16,262
blue oceans
and verdant landscapes.

1465
01:52:16,296 --> 01:52:18,231
And they can only be solved
with the help

1466
01:52:18,264 --> 01:52:25,138
of these eyes in the sky looking
down at earth from space.

1467
01:52:40,954 --> 01:52:45,391
Major funding for <i>NOVA</i>
is provided by:

1468
01:52:45,425 --> 01:52:48,928
Supporting <i>NOVA</i> and promoting
public understanding of science.

1469
01:52:50,797 --> 01:52:52,966
And the Corporation
for Public Broadcasting,

1470
01:52:52,999 --> 01:52:54,067
and by:

1471
01:52:55,802 --> 01:52:58,271
And Millicent Bell, through:

1472
01:53:01,107 --> 01:53:04,077
Major funding for "Earth
from Space" is provided by:

1473
01:53:06,112 --> 01:53:08,848
Furthering the values that
contribute to a healthy planet.

1474
01:53:26,533 --> 01:53:30,103
<i>This</i> NOVA <i>program is available</i>
<i>on DVD and Blu-ray.</i>

1475
01:53:30,136 --> 01:53:35,441
<i>To order, visit shoppbs.org</i>
<i>or call 1-800-PLAY-PBS.</i>

1476
01:53:35,475 --> 01:53:38,311
NOVA <i>is also available</i>
<i>for download on iTunes.</i>

1477
01:53:42,682 --> 01:53:38,311
Captioned by
Media Access Group at WGBH access.wgbh.org

1478
01:53:41,311 --> 01:53:45,311
Preuzeto sa www.titlovi.com