NARRATOR: Our planet: Earth.
You may think you know it well.
But a startling new picture is emerging
of a world shaped by forces
more dynamic and intertwined than we ever imagined,
raising possibilities that defy common sense.
How can sandstorms in the Sahara Desert
transform the Amazon rainforest over 5,000 miles away?
In the frigid ocean beneath Antarctica,
how can a vast undersea waterfall
500 times bigger than Niagara Falls
lead to a gigantic feeding frenzy near the equator?
And how can warm water streaming past the coast of Africa
trigger a weather catastrophe
half a world away in the southern United States?
Scientists have begun to find surprising answers
to these and other profound questions
thanks to a network of satellites
orbiting high above the earth.
Ever watchful,
their senses extend far beyond what our eyes can see.
EMILY SHUCKBURGH: It's really the last bastion of human discovery.
We're discovering new things every day.
NARRATOR: What are these hidden forces that rule our world?
How are the oceans, the continents, the atmosphere
and even the sun bound together,
and how do they affect all living things?
For the first time, we can understand
how earth, fire, wind and water join together
to create the dynamic environments
that shape life in all its forms.
WALEED ABDALATI: Their interaction
is what has created the environment, the diversity,
the kind of life we see on earth today.
NARRATOR: With astonishing images
created from a wealth of new information from satellites,
this is our planet as never seen before.
"Earth from Space," right now on NOVA.
♪ NOVA 40x11 ♪ Earth From Space Original Air Date on February 13, 2013
== sync, corrected by elderman ==
Major funding for NOVA is provided by the following:
NARRATOR: Since humans first ventured into space,
some of the greatest gifts of exploration
have been the new views of our home.
Who can forget the iconic "earthrise" images
of the Apollo era?
And now from the International Space Station,
we have these spectacular vistas.
The blue marble is finally revealing its secrets.
It's a planet alive with activity and constant change,
its surface transformed by humans
yet still ruled by powerful natural forces
that we are only beginning to understand.
ABDALATI: It's just spectacular when you view it from space.
It's teeming with diversity, with beauty.
Amazing colors, you know,
the blues and the greens and the whites.
PIERS SELLERS: You see the world
as one huge system
all linked through the atmosphere and the oceans,
rolling its way around the sun.
NARRATOR: So what is it that shapes Earth's dynamic face?
What are the essential ingredients,
and how do they combine to generate and sustain all life?
How do the natural forces that surround us work together
to create an engine powerful enough
to nourish and drive life forward in all its diversity?
Our best hope for answers may come from above.
Orbiting over our heads are 120 satellites
keeping watch from space.
Most operate at altitudes
ranging from a few hundred miles above the surface of the planet
to as high as 25,000 miles.
Each one of these Earth-observing satellites
reveals a different piece of the puzzle.
Each carries an array of exquisitely sensitive detectors,
designed to reveal what would otherwise
be hidden from our view.
The satellites are absolutely amazing
because not only can we see visible things from space,
but also we can see things that aren't visible to the human eye.
So satellites are enabling us
to turn what are invisible processes
into visible things we can see and then understand.
NARRATOR: To see how our world works, in this program
we have taken information provided by satellites,
combined it with computer models,
and rendered the results
in these scientifically accurate graphics.
With the invisible now revealed,
we can see Earth as an endlessly changing system.
These images will show in great detail
how sunlight, moisture, land and atmosphere interact
in unexpected ways,
with seemingly local events
often triggered by forces far away in space and time.
And with these new insights, for the first time,
scientists can begin to understand
the intimate relationship between the planet
and all the living things it supports.
ABDALATI: It's really the thrill,
because it matters so much,
of piecing together the story of what the earth is doing,
how it's changing, why it's changing
and how ultimately that affects humans.
NARRATOR: The first piece of the puzzle
is in understanding the massive influence the sun,
from 93 million miles away, has on our planet.
The world's continuously bathed
in a flow of energy from the sun.
That warms the earth.
Everything that you can see that lives and breathes
and moves on the earth is pushed by the sun.
NARRATOR: Now an electronic eye in space
can measure the impact of the sun's energy
all around the earth.
One of NASA's newest satellites,
named for a meteorologist, polar-orbiting Suomi,
launched in 2011, provides the view.
The spacecraft is the size of a small school bus.
It orbits 500 miles up, circling the planet 14 times a day.
On board, it carries five separate sensors
that enable it to see things invisible to human eyes.
The light that we can see
is confined to a narrow band of electromagnetic radiation,
just a tiny portion of what the satellite can pick up.
Electromagnetic radiation spans a spectrum
that goes far beyond the familiar colors of the rainbow.
ABDALATI: If you were to consider the full spectrum to be a line
that stretched from New York City to Los Angeles,
the piece that our eyes could see
would be about the size of a dime.
There is so much other information out there
available to us,
and that's in large part what these satellites do.
NARRATOR: One of this satellite's key instruments is called CERES,
an acronym for Clouds and Earth's Radiant Energy System.
It detects a broad range of the spectrum,
including the very short and very long wavelengths of light
in the ultraviolet and infrared that we can't see.
This is a CERES-eye view of the planet.
Anything that emits heat gives off infrared radiation,
so the CERES data shows the earth in shades of heat,
accurate to a fraction of a degree.
It reveals how the planet as a whole reacts to sunlight,
both absorbing and reflecting the radiation
coming from our local star.
At the poles, the sun strikes at an oblique angle,
and what little light there is
gets reflected back out to space by the ice and clouds.
These are the primary reasons why the poles remain cool.
At the equator, it's a very different story.
Not only does the planet receive more direct sunlight here,
the lack of ice means that
less of the sun's energy is reflected back into space.
And at the equator,
the sun's concentrated energy fuels a heat engine
that can trigger weather events around the world.
Perhaps the best place to see the impact of the sun's heat
is an area in the Atlantic
just north of the equator and west of Africa:
the coastal waters of the Cape Verde islands.
Here, the sea provides a living.
The local fishermen keep a careful eye on the weather.
They know that storms can bring a good catch.
Turbulent weather stirs up nutrients from the deep,
attracting great shoals of fish.
It's the hottest time of the year,
and the sun beats down relentlessly.
By late afternoon, the huge inflow of heat energy
has led to the buildup of large cloud formations.
Sometimes, these formations develop into massive storms.
It's a process that satellites are revealing in fine detail.
Circling above the fishermen is a NASA satellite called Aqua--
Latin for "water."
It orbits the poles.
One of its key tasks is to monitor the complex interaction
between sunlight and water.
JEFFREY HALVERSON: Aqua satellite is one of NASA's flagship satellites.
Its primary function is to study the hydrologic cycle on Earth:
vapor in the atmosphere, liquid ocean,
the temperature of that ocean and the ice.
NARRATOR: One of Aqua's instruments
looks down at the sea around Cape Verde,
again in infrared, sensing heat.
Highlighted here in yellow,
over one million square miles of ocean
reaches a critical temperature: 80 degrees.
At this temperature, the sea is evaporating fast,
producing an invisible gas: water vapor.
SHUCKBURGH: By looking at the infrared, the Aqua satellite
is able to measure the amount of water vapor evaporating
from the surface of the ocean.
NARRATOR: Aqua shows that this area
is producing millions of tons of water vapor every hour.
Based on that data, it's possible to create an image
of what the vapor might look like
if these fishermen could actually see it
in the air around them.
Water vapor is much lighter than air,
and vast columns rise upward,
directly from the surface of the sea.
The water vapor carries with it heat, the energy of the sun.
HALVERSON: Well, water vapor is like invisible energy.
It's like molecules escaping the ocean,
taking heat energy with them,
and they're like little mobile solar collectors
that are zipping around the atmosphere.
NARRATOR: Half a mile up, as the air cools,
the water vapor condenses back into liquid water--
tiny droplets that form vast clouds.
The vapor releases the sun's energy,
the heat it received earlier.
The result is a storm.
HALVERSON: Molecules condense in the atmosphere
and become liquid again,
and when that happens,
that heat is given off into the atmosphere
and it warms the atmosphere,
and that's the heat that powers storm systems.
NARRATOR: In the worst storms, the heat captured by the water vapor
is equivalent to up to 200 times
the global production of electricity at any given moment.
The process of evaporation results in something
we don't need special instruments to see.
The rising heat drives the clouds up to ten miles high.
As the clouds rise upward,
the earth's rotation causes them to spin.
The thunderclouds merge into a vast vortex.
This is the birth of a hurricane.
(loud winds blowing)
It is 2005, the busiest hurricane season on record.
On August 27, a meteorological satellite
is tracking a category three hurricane
that started in the Bahamas.
Its name is Hurricane Katrina.
Throughout the region,
there is one question on everyone's mind:
will the hurricane hit land, or will it blow itself out?
The answer may come from a NASA satellite called TRMM,
the Tropical Rainfall Measuring Mission.
TRMM is equipped with a radar and imager
that operate in the microwave range of the spectrum.
These are higher in energy
and shorter in wavelength than other radio waves.
The instruments bounce microwaves
off raindrops in the clouds,
allowing scientists to build a three-dimensional model
of the internal structure of a hurricane.
HALVERSON: We can actually look at microwave energy
which is generated within the clouds
and coming from the ocean's surface.
It's almost as if the clouds are now invisible to us;
we can see right through them like taking a CAT scan
to look inside those clouds.
NARRATOR: This satellite is a powerful tool,
and now its sensors reveal something ominous.
Huge, vertical columns of warm water vapor
burst up from near the center of the storm.
Almost like hurricanes within hurricanes,
these climbing vortices deliver added infusions of energy
into the heart of the storm, fueling its growth even more.
These new sources of energy are called hot towers.
HALVERSON: If they occur in the right place at the right time,
near the very center of the system,
they can be like a giant spark plug
that gets that whole engine running
at very, very high speed.
NARRATOR: The hot towers draw more and more water vapor off the ocean.
This triggers a feedback loop
that leads to a runaway reaction.
In just 24 hours,
Hurricane Katrina grows into a category five monster.
(loud winds blowing)
(screaming)
NARRATOR: All this violence is a direct result
of the power of the sun on the ocean.
Ferocious winds blow for two days straight,
reaching 175 miles an hour,
twisting steel like paper
and ripping apart homes and buildings.
Over three trillion gallons of rain a day
and a massive tidal surge from the Gulf of Mexico
combine to inundate whole areas of the Gulf Coast.
Katrina leaves its mark across 90,000 square miles.
Over a million people are displaced.
Katrina becomes the standard
by which future hurricanes will be assessed.
But even this extreme hurricane
is just a tiny brushstroke in a much bigger picture:
a picture of how the sun drives water around the entire planet
with radically different effects in different places,
all under the watchful gaze of our eyes in space.
Take just a single day in July.
In New York, commuters swelter in 95 degree heat.
Searing winds pump hot air into the region from the south,
creating oppressive, humid conditions.
7,000 miles away, in Mumbai, India,
commuters here struggle to cope with torrential rain.
The deluge comes so fast
that the streets are flooded in hours.
Meanwhile, in Chile,
the desert of the Atacama is almost totally dry.
There are places here
where rainfall has never been recorded.
Such diverse environments, thousands of miles apart,
appear totally unrelated.
But by pulling back for a wider view,
we can see that they are in fact intimately connected.
Orbiting 22,000 miles from Earth's surface
is a chain of five weather-tracking spacecraft,
including this one: NASA's GOES East.
GOES is an acronym
for Geostationary Operational Environmental Satellite.
Each moves in a fixed position relative to the earth,
called a geostationary orbit.
They always look down on the same parts of the planet.
The combined data from these five satellites
gives scientists a unique perspective on the earth.
SHUCKBURGH: By having several of them
located at different positions around the equator,
we're able to get a view of the whole earth
24 hours a day.
NARRATOR: By observing the entire earth, these satellites reveal
how energy moves throughout the globe,
beginning with the impact of the sun on water.
The process is the same everywhere,
but the outcome will be very different in different places.
Converted from the numerical data,
these five circles graphically depict
what the satellites actually sense.
They reveal the total picture of water vapor produced on earth
in a single frame.
Seen here in fast forward, one second is equal to a day.
It shows how water vapor produced at the equator
continuously transports the sun's energy towards the poles.
Local landscapes and topography affect the vapor's impact,
with results unique to each region.
In India at the end of July,
the warm water vapor is drawn from over the ocean
by the difference in temperature between land and sea.
Rising to high altitude,
the vapor cools over the land and condenses back into water.
We call the result the Asian Monsoon.
Nearly a trillion tons of rain falls out of the sky,
transforming parched land into fertile plains.
The monsoon eventually moves to the east, reaching China,
where it floods the paddies that are ideal for growing rice.
This process helps provide food for three billion people,
almost half the world's population.
Meanwhile, on the other side of the world in South America,
westbound winds drive water vapor
across the high peaks of the Andes.
The altitude strips the air of its moisture,
which falls as snow on the mountains,
creating on the far side in central Chile
the arid desert of the Atacama.
That same July day in the eastern United States,
hot, moist air surges north
straight from the Gulf of Mexico.
With no natural barrier in the way,
more than 100 million Americans, from Memphis to New York,
swelter in the summer heat.
This graphic,
based on information provided by satellites,
depicts the interaction between the atmosphere and the oceans
as they connect in a global pattern of circulation
that results in our local weather.
SHUCKBURGH: The satellite data shows that
it's all one interconnected system,
but that in different parts of the world,
different processes are happening.
We can see the monsoons and their effect.
We can see the effects on deserts
in a different part of the world.
And that together shows us
how water vapor is connecting with life on earth.
NARRATOR: But this vast cycle of sunlight, water and land
is just one pattern among many on this planet we call home.
A cycle with even greater consequences
for the long-term climate involves extreme cold.
To see how that works, we have to turn the earth upside down
and look at it from below.
Antarctica remains the earth's last great wilderness,
a vast frozen continent plunged in darkness
for almost six months of each year.
In winter, temperatures can drop
below minus 110 degrees Fahrenheit,
and an incessant 100-mile-an-hour gale blows.
It's hard to believe that anything life-giving
could start here in this bleak place.
But that's exactly what happens.
Antarctica's ice plays a vital part
in maintaining global climate,
sustaining life even in lush, warm jungles
thousands of miles away.
ABDALATI: Antarctica is a fundamental element of the climate system.
And while it may sit silently and majestically
at the edge of the planet for very few to see,
things go on there
that spread out all over the world,
that affect the world as a whole.
NARRATOR: It's a paradox that such a bleak and barren place
is so critical to life on our planet.
On average, it's 43 degrees colder than the North Pole.
Why should Antarctica be so much colder,
and how does that affect the rest of the world?
The detectors on NASA's polar-orbiting satellite Suomi
provide part of the answer.
The instruments sense
in the infrared and ultraviolet parts of the spectrum.
They show that the poles receive little of the sun's energy
and reflect most of it back out into space.
That's one reason why the poles stay cold.
But there's another factor that makes Antarctica colder still.
This image has been pieced together
from 17 different satellites
that sense the infrared, or heat.
The continental mass of Antarctica
lies beneath this swirling maelstrom of cloud.
A computer model of the data shows what happens
as the warm moist air arriving from the tropics
collides with the cold air over the South Pole.
The result is a massive storm system.
And just like a hurricane,
it rotates as a result of the spin of the earth.
Only this is much larger than a hurricane,
4,000 miles in diameter.
Where that cold air and warm air meet high up in the atmosphere,
the air starts to rotate around Antarctica.
The winds can be up in the atmosphere
as much as 200 miles an hour.
NARRATOR: This circulation pattern is called the polar jet,
a ceaseless circle of wind and storms.
The relentless clockwise wind, seen here in yellow,
drives the seawater below, shown in light blue.
DAVID ADAMEC: Those strong winds are sending a jet around in the ocean,
and it's driving an ocean circulation
that is felt almost all the way to the bottom of the ocean,
two and a half miles deep.
NARRATOR: The Southern Ocean rings the continent
with no land to interrupt a vast body of moving water.
This is the Antarctic Circumpolar Current.
And these are the "Screaming Sixties,"
the roughest, most dangerous seas on the planet.
Here, storms rage almost every day of the year,
whipping hundreds of trillions of gallons of water
into a ceaseless frenzy.
Now the infrared instrument on the Aqua satellite
which senses atmospheric temperature
puts the pieces of this puzzle together.
The winds of the polar jet
and the water of the circumpolar current
together form an impenetrable barrier around Antarctica,
isolating it from the rest of the planet
and depriving it of warmth.
That is why the whole region
remains exceptionally cold all year round.
ABDALATI: What's incredible about what the satellites tell us
is that the movement of air
and actually the movement of ocean current
around the perimeter of Antarctica
isolates the continent from the rest of the world.
NARRATOR: So why is this relentless cold so important to the planet
way beyond Antarctica?
The answer lies in a remarkable property of water:
what happens when it freezes.
The Aqua satellite reveals the start of the process.
It sweeps the surface with its microwave scanner,
looking through the clouds
to detect the distinct signature of ice.
SHUCKBURGH: The microwave instruments on the satellite
enable us to see through the clouds
to the sea ice around Antarctica throughout the year.
What's particularly incredible about that is
we're able to take measurements of the sea ice
in places where as scientists, as humans, we can't even go.
NARRATOR: This satellite gives us an accurate picture
of the extent of sea ice around Antarctica
over the course of a year.
Seen here in summer, Antarctica is nearly
one and a half times the size of the United States,
covered in ice.
But in winter, it grows even more.
Over five and a half million square miles of ice form
around the continent.
It grows to the size of all of Africa.
This vast ice formation has a profound effect
on life across the planet.
How can its impact extend so far?
One of the best places to understand the power of ice
is the huge bay
along the northwestern coast of Antarctica: the Weddell Sea.
Here, a constant gale blows and cools the seawater
to freezing temperatures.
Once the upper layer of ocean
falls below 29 degrees Fahrenheit,
a critical threshold is crossed.
The surface of the ocean begins to freeze.
(crackling)
At a microscopic level, tiny crystals start to grow,
knitting themselves together.
As the crystals bond, they expel salt into the water.
The salt forms brine that drips down long, narrow tubes
and holes in the ice as it forms.
The brine is denser than regular seawater and it sinks downwards.
As winter's grip tightens,
the formation of ice speeds up and spreads.
Soon, large slicks appear on the surface
and thicken into a solid mass.
What started as a microscopic process
can soon be seen from space.
Each year, more than 200 billion tons of ice form
in the Weddell Sea alone,
releasing tens of trillions of tons of dense brine
into the ocean.
The fate of all this brine is a mystery.
The crucial question is where does it all go?
A satellite called Jason,
jointly operated by NASA and the French space agency,
is providing new answers.
Jason bounces radar signals off the surface of the ocean
to measure its height.
The instrument also reveals
the shape of the sea floor far below.
We can make very accurate maps of submarine bathymetry.
But we don't do that directly;
we do that by measuring the surface of the sea from space,
very, very accurately and over time.
NARRATOR: Jason's radar is so precise
that it can detect minute changes
in the level of the sea surface
produced by the peaks and valleys of the terrain below.
The data makes it possible to map the ocean floor.
ADAMEC: You have a satellite that's up there, 500 miles up in space,
and it's returning an accuracy
of a little less than half an inch.
What that means is, you know,
I've stuck this instrument in Washington, D.C., say,
and I'm looking at a crowd of people in Boston
and I can tell you whether or not their toes
are over the curb or not.
That's what this satellite is doing.
NARRATOR: The satellite data
allows scientists to make a three-dimensional map
of the ocean floor beneath the Weddell Sea.
It reveals a vast chasm, two miles deep,
off Antarctica's continental shelf.
As the brine descends into the ocean,
it eventually falls over this precipice.
Other sensors attached to the sea floor
track the flow of the brine as it sinks.
SHUCKBURGH: What we're really excited about is that
we're able to take that data
that shows us what the bottom of the ocean looks like
and combine it with data from sensors under the water.
And that enables us to look at the dense water
and where it goes.
NARRATOR: Combining data from satellites and undersea instruments,
scientists can reconstruct what is happening
hidden beneath the ice.
What they learn is astounding.
One trillion gallons of salty brine
plunge down through the Weddell Sea every hour,
a torrent equivalent to the volume of 500 Niagara Falls.
The brine spreads out towards the edge
of the Antarctic continental shelf
and then falls into the chasm revealed by Jason.
A vast submarine waterfall plummets downward.
The cold, dense brine
falls slowly, silently, into the abyss,
two miles down to the ocean floor below.
It will not resurface for hundreds of years.
What happens to the brine next is still being investigated.
But computer models combined with satellite data
are helping scientists to figure out where it goes.
This animation shows the undersea current in action.
The purple area is the brine.
The outflow from Antarctica
drives the salty water towards the equator,
along the sea floor.
ADAMEC: All the water in the bottom of every ocean around the globe
has its start within six miles of the Antarctic continent.
It creates the coldest, densest water that's on the planet.
NARRATOR: The cold, salty liquid
becomes part of a worldwide circulation system,
stirring and cooling all the world's oceans.
Leaving Antarctica, it has embarked on a journey
that could take 1,000 years to complete.
As it migrates towards the equator,
the cold bottom current mixes with fresher and warmer water
and slowly rises.
It then joins other ocean currents
and eventually returns south, where it cools once more.
Finally, returning to Antarctica,
the seawater freezes and releases its salt again,
completing the cycle.
It's an endless loop that is critical to the whole planet.
ABDALATI: The importance of dense water in Antarctica is that
it really forms the basis of global ocean circulation.
The temperature and the salt combine
to cause sinking and rising in different parts,
which sets up this conveyor belt,
this interaction of all of the ocean water.
NARRATOR: In the Arctic, frigid winter winds cause the ocean to freeze.
The North Atlantic currents cool and sink to the bottom,
then head south again.
All over the world, slow-moving currents of seawater like this
regulate the average temperatures of the oceans
to within one degree.
This stability has a profound effect on life
all across the world.
This NASA simulation shows the surface of the entire ocean,
a web of currents in constant motion.
But satellites show us that the oceans don't work alone.
The currents affect the air, the atmosphere,
that sits above them.
The ocean and atmosphere are intimately connected.
For instance, the Gulf Stream
takes warm water from the Gulf of Mexico
north to the eastern United States and Europe,
generating warm air.
On the other side of the world,
another current called the Kuroshio
carries heat from China north to Japan.
ocean currents distributing heat around the planet.
The climate we live in
is a result of ocean circulation patterns.
The reason in the United States
that North Carolina and South Carolina are warm
is because there is the Gulf Stream.
And the reason there's a Gulf Stream
really takes root in Antarctica.
NARRATOR: As a major engine driving the world's ocean currents,
Antarctica helps protect Earth's climate
from wild swings in temperature.
The constant, dependable circulation
of the oceans around the globe
and the relatively stable temperatures it produces
have made Earth a hospitable planet.
Long-term stability provided time for life to flourish
and complex animals and plants to evolve.
And this is how a process that began with Antarctic ice
continues to sustain our world.
ABDALATI: When you put it all together, you get a story
of how ocean circulation affects climate and weather
and what that means today, tomorrow
and 20 years out into the future.
(rumbling)
NARRATOR: But ocean currents and the atmosphere
are not the only players.
Beneath the sea floor,
forces inside the earth are a crucial source
for the basic materials that nurture life.
This hidden mechanism is driven by ceaseless,
often violent activity.
Two recent examples:
A magnitude nine earthquake strikes Japan in 2011.
An entire section of the country
moves eight feet towards North America.
A year earlier, 2,500 miles to the south in Papua New Guinea,
the volcano Rabaul erupts.
It fires a vast plume of ash high into the atmosphere.
These are catastrophic, hugely destructive events
with an enormous cost in human lives.
But the natural forces behind these disasters
also provide the materials
we and other living organisms need to survive.
And satellites help show us how this happens.
Canada's RADARSAT is one of several satellites
that use highly sensitive radar
to map the earth's surface in three dimensions.
Bouncing radio waves off the terrain below,
these satellites continually sweep the surface of the globe.
They can measure the height of the earth's surface every day
to an accuracy of less than a quarter of an inch.
When the data is plotted over time,
we can see in fine detail
how the earth's crust is constantly moving.
This is the surface of the crater
atop Mount St. Helens in Washington state.
Animation reveals how it swells over the course of three weeks,
driven by a surge of molten magma beneath the crater.
Satellites can actually see the crustal plates moving now.
We can see bulges and dips
where the magma is moving around underneath the crust.
NARRATOR: This animation shows the swelling of Mount Etna in Italy
as magma accumulates beneath it over nine years.
When the volcano erupts, the land sinks back.
SELLERS: So we're getting a picture now
of what the world looks like under the crust
and how that affects the other dynamic processes
of the so-called solid earth.
NARRATOR: Every day, dozens of volcanoes around the world are erupting,
while 4,000 earthquakes shake the ground.
Our earth is dynamic,
constantly ejecting gases and magma from its depths.
And some of this activity has a vital impact on life.
The secret to understanding how
lies deep beneath the ocean's surface.
Here, a crucial chemical reaction takes place
between molten rock and deep ocean water.
The Jason satellite's sea surface-mapping radar
reveals a chain of active volcanoes
a mile and a half down, at the bottom of the Pacific Ocean.
This is where that critical interaction
between molten rock and freezing water takes place.
This footage was taken with a remotely operated submarine,
also called Jason.
Lava and superheated gases
spill out of cracks in the ocean floor,
known as hydrothermal vents.
Jason reveals what happens
when cold ocean water penetrates into the cracks.
A magma chamber below heats the water
to up to 750 degrees Fahrenheit.
In the pressure-cooker environment inside the cracks,
the dense salty water actually dissolves the solid rock.
Complex chemical reactions take place,
producing minerals containing sulfur and iron.
These are nutrients that living organisms need to survive.
The seawater, now loaded with minerals from inside the earth,
streams out of the hydrothermal vents.
These nutrients feed a thriving ecosystem
that includes shrimp and exotic creatures like tubeworms.
The deep ocean currents carry the leftover nutrients away.
Over thousands of years, they circulate through the oceans,
ultimately rising to the surface
and contributing to an amazing explosion of life.
And we can see this activity with NASA's Aqua satellite,
which is equipped with instruments
that observe the earth
in many wavelengths of the electromagnetic spectrum.
One tool is called MODIS.
MODIS is pretty much the crown jewel of the Aqua satellite.
It's an enormous scanner.
So it basically covers the whole world every day.
NARRATOR: MODIS scans the ocean in the infrared
and the visible portions of the spectrum.
It can detect extremely subtle changes in the temperature
and color of the water.
So what we have in space is an instrument
that looks at very, very small parts of the spectrum,
and we measure how much light comes back
in each part of the spectrum.
NARRATOR: Looking down at the west coast of South America,
MODIS detects an upwelling of cold water
150 miles west of Peru.
Then it detects a particular shade of green.
This identifies the source as chlorophyll,
a sign of plant life.
It's clear that the satellite has spotted a massive bloom
of tiny organisms called phytoplankton.
Just below the surface, these phytoplankton are absorbing
the rich soup of minerals that have come from the deep ocean.
And with light from the Sun,
and carbon from the carbon dioxide in the air,
they multiply by the billions.
As MODIS shows, the plankton multiply so quickly
that in just 24 hours, 500 square miles of ocean
have turned to this distinctive green color.
GENE FELDMAN: They replicate very, very fast.
So you can have a plankton bloom
that doubles over the course of a day
and can cover hundreds or thousands of kilometers
of the ocean surface.
NARRATOR: It's the minerals from beneath the earth's crust
that have helped fuel this vast explosion of plankton--
over 800 thousand tons of living material.
And that's only the beginning.
This plankton is the base of the food chain for marine life.
The bloom triggers one of the largest feeding frenzies
on earth.
Trillions of anchovies and sardines
feast on the tiny organisms.
They, in turn, attract larger predators
to one of the densest concentrations
of marine life anywhere.
Sharks converge.
And even birds, flying above, dive down to join the feast.
And up above, humans are here, too, taking advantage
of one of the world's most productive fishing grounds.
The satellite data reveals similar upwellings
all around the world, delivering nutrients, seen here in pink,
into the surface waters.
Each upwelling triggers a plankton bloom.
FELDMAN: Phytoplankton provide that key link
between this energy out here,
the raw materials that this planet holds
and the food engine that allows life to flourish.
NARRATOR: These vast green ribbons of plankton
can cover as much as a fifth of the world's ocean surfaces,
about 45 billion tons of biomass every year.
The plankton are one link in a chain of life
that begins deep beneath the seafloor.
The most important plant life on this planet
are these microscopic little green plants
that float in the ocean.
NARRATOR: Plankton may be key to life,
but they themselves don't live long.
MODIS shows how, in just 72 hours,
a bloom can rapidly weaken and fade.
All the plankton that have not been eaten
die and sink into the abyss.
They take their precious minerals with them
all the way back to the ocean floor.
Here they will remain for millennia,
a thick carpeting of tiny carcasses half a mile deep.
Some of the minerals may ultimately be recycled.
Some may emerge through hydrothermal vents again,
millions of years from now.
But some plankton,
through yet another extraordinary chain of events,
will deliver their precious cargo of nutrients
not just to life in the ocean, but also to life on land.
Half a world away from the coast of Peru, where plankton bloom,
lies the Sahara Desert in North Africa.
The Sahara is enormous--
it makes up a tenth of the African continent.
It's one of the driest and dustiest places on earth.
Surprisingly, the remains of ancient plankton are here,
hidden in this arid landscape.
It is May, the hottest month of all.
Camel herders travel through one of the most exposed regions
of the Sahara: the Bodele Depression.
Six thousand years ago,
this was covered by the world's largest freshwater lake.
The floor of the lake is covered with the ancient remains
of plankton-- called diatomite-- laid down in a much earlier age,
when an ocean covered the region.
With its eye on the earth from 400 miles above,
NASA's Landsat 7 is one of the latest generation of satellites
studying the composition of rocks that make up our planet.
It sweeps the Bodele, producing these high resolution pictures
in multiple wavelengths of visible light.
The white expanse is the diatomite
on the bed of the lake.
The size of the lake is over a thousand kilometers long
and 600 kilometers wide.
But with a satellite image, we can see the whole extent
of the basin on a series of images
and visualize that on a computer in a matter of minutes.
NARRATOR: The satellite image analysis
shows over 24,000 square miles of sediment,
all of it diatomite.
We can map where the diatomite sediment is
on the floor of the lake.
NARRATOR:The diatomite from the plankton is a rich source of phosphorous,
an element needed by all living things to produce energy.
But for this nutrient to re-enter the chain of life,
it must first embark on a long journey
that can be seen from space.
The journey begins here on the ancient lakebed in the Sahara.
The wind sweeps up a few flakes of diatomite into the air.
The flakes fracture into a fine powder
and are carried off by the wind.
A dust storm builds.
22,000 miles above, the European weather satellite Meteosat 8
looks down from its geostationary orbit.
It records a daily pulse of dust
rising off the Bodele Depression.
Here it's visible as a whitish dust cloud
lifting from the desert with clockwork regularity
at noon each day.
BRISTOW: Although the individual particles of dust are minute--
they're hundredths or thousandths of a millimeter
in diameter-- there are such vast clouds of this dust
that you can see it on satellite images.
NARRATOR: The dust cloud is over a hundred stories high
and 200 miles wide.
From here it will head west on an epic journey.
Seen from space, the dust is blown across Africa.
At the Atlantic coast, it's drawn up high into the sky.
This simulation, based on satellite data,
shows how prevailing winds carry the dust cloud west and south
3,000 miles across the Atlantic.
As much as 7,000 tons of dust are airborne at any one time.
The destination is set by the winds:
South America and the Amazon.
We're taking literally thousands of tons of this dust,
which is containing phosphate,
and exporting that from the Bodele.
The wind is carrying it out
across the Atlantic to fertilize the Amazon.
NARRATOR: Here in these clouds high above the rainforest,
what was once living plankton reaches the end of its journey.
The minerals in the dust,
which include energy-giving phosphorous,
dissolve into water droplets
and fall to the Amazon in rain.
BRISTOW: Areas like the Amazon jungle, although they appear very rich,
the soils are actually very depleted, they've been leached.
And one of the things that they're short on is phosphate.
NARRATOR: Rain falls incessantly
throughout the Amazon's wet season,
delivering thousands of tons of phosphate into the forest below.
It passes into the soil and the roots of the trees,
nourishing the rain forest.
The effect of all this natural fertilizer
can be seen clearly from orbit.
Terra is the twin of the Aqua satellite.
It circles the earth every 99 minutes,
monitoring how fast vegetation is growing.
SELLERS: We can see all the green vegetation on earth--
wall to wall, every day--
and it tells you almost everything you want to know
about the state of life on earth.
NARRATOR: With its color scanner,
Terra can see the effect of the Sahara dust on the Amazon
at the end of the rainy season.
It observes an increase in the distinctive green color
of chlorophyll.
Like the plankton blooms in the ocean,
the forest is kicking into overdrive...
watered by rain and nourished by the minerals
borne across the Atlantic by the dust cloud.
For every leaf that exists now, three more will grow in a week.
It's the culmination of a chain of events
that began far back in time and halfway around the world.
SELLERS: Ancient sediments laid down by other organisms
millions of years ago get eroded, make dust,
the winds bring them across the Atlantic,
fertilize the tropical forest in the Amazon.
NARRATOR: The migration of Bodele dust to the Amazon
is just one of many ways that vital minerals spread
to living habitats all over the world.
Every landscape has its own story
and its own way of entering the chain of life.
BRISTOW: The exchange of nutrients from the land
is going on all over the globe every day.
NARRATOR: And in certain areas, this is what accounts
for the special productivity of the soil.
The Great Plains of North America are rich in minerals
eroded from the Rocky Mountains.
These are vital ingredients for growing wheat and corn.
In Bangladesh, the Ganges delta is rich in iron
washed down from the Himalayas in river sediments,
ideal for growing rice.
The hidden transport of minerals creates fertile soils
that enable plants to thrive.
These minerals are the basis of the food chain
for all life on land, including us.
SELLERS: All of this reminds you
how interconnected the earth system is...
...that no living thing lives in isolation from processes
that may happen a long way away
in both space and time from itself.
NARRATOR: Satellites provide a vivid new perspective on the links
between land, sea, air and life.
This new perspective helps us see
how the natural forces of our planet fit together,
and that includes the atmosphere
and something as basic as the air we breathe.
Less than a quarter of the air around us
is comprised of oxygen, but that oxygen is essential to life.
It's what all animals need to burn fuel in their bodies.
Oxygen is vital to metabolism.
It provides the energy
that allows even the most active creatures to survive and thrive
and to master their environments.
Scientists believe that the abundance of oxygen
in the atmosphere was essential for the evolution of large,
intelligent mammals like us.
The human brain alone uses about 20% of the oxygen we breathe.
But where does all this oxygen come from?
Satellites can help us answer that question.
NASA's Aura satellite is one of several spacecraft
that are helping scientists study the earth's atmosphere.
Along with ground instruments,
it can analyze the atmosphere and pinpoint its composition.
It builds a picture of the nitrogen,
oxygen and carbon dioxide
that together make up 99% of the air we breathe.
This computer visualization shows
how the earth's atmosphere changes over 24 hours.
During the day, oxygen-- seen here in blue--
rises all over the planet.
At night, carbon dioxide-- shown in orange--
is on the rise.
And the oxygen we need is given to us by plants.
Before plants, there was no oxygen in the atmosphere.
So plants did all the hard work
of allowing the atmospheric concentration
to build up over time, allowing all other life to develop.
They made the place habitable for us.
NARRATOR: Plants breathe in carbon dioxide and expel oxygen.
They produce so much that the vast Amazon rainforest
is often called the lungs of the earth.
But the real picture is more complex.
The verdant wilderness of plants and animals
is one of the oldest, most abundant living systems
on earth.
Over two million square miles of lush rainforest
teem with half the world's living species.
SELLERS: The Amazon is
the largest natural preserve of life on the continents
that's left in the world.
Thousands of miles of almost virgin forest,
thousands of species that have been there
for an awfully long time.
NARRATOR: So dense is the Amazon jungle that it has a dramatic impact
on the air above it.
It starts in the trillions of leaves far below.
We can use animation to show what this invisible process,
known as photosynthesis, might look like.
During the day, the leaf takes up carbon dioxide from the air,
seen here in orange.
It converts the carbon into sugar for energy and growth
and releases oxygen, seen in blue.
Each one of these trees will release
hundreds of thousands of cubic meters of oxygen
in the course of its life.
And as for the Amazon as a whole,
a fifth of the world's oxygen is produced here.
But there's a surprising twist:
we will breathe almost none of it.
Satellite data and ground measurements reveal
that almost all the oxygen the Amazon produces during the day
remains there and is reabsorbed into the forest at night.
SELLERS: With the advantage of the satellites,
we can now see that the Amazon
basically uses all its own oxygen
and uses all its own carbon dioxide.
It is, as far as we can tell,
almost a closed system in itself-- almost.
NARRATOR: But the Amazon still plays a vital part
in generating the oxygen that we breathe.
What satellites now make clear is
producing the oxygen that benefits us takes an extra step.
The process begins with rain,
which falls up to 250 days a year in the Amazon.
The soil of the rainforest
is continually washed into the Amazon river system,
taking with it nutrients and organic material.
An average of two million tons of this sediment
is released every 24 hours.
The sediment flows eastward,
traveling 4,000 miles into the Amazon delta.
Here, microscopic plankton near the surface thrive
on the nutrients and their population explodes.
As they spread further out to sea,
some of these tiny organisms act like plants,
absorbing carbon dioxide and releasing oxygen.
Again the Aqua satellite shows us how a giant plankton bloom
grows to cover 25,000 square miles.
This vast area translates into a huge boom in oxygen production,
made available to the entire planet.
FELDMAN: When plankton grow, they release oxygen.
That oxygen ultimately finds its way into the atmosphere.
NARRATOR: The massive scale of this impact
is revealed when the satellite data is visualized.
This animation shows the oxygen produced by plankton blooms,
seen here in bright blue.
The Amazon plankton bloom releases billions of gallons
of oxygen into the atmosphere every day.
Within a few days the plankton die,
leaving most of the oxygen they produced in the air
as they sink to the bottom of the ocean.
Similar explosions of microscopic life
happen all over the world.
Plankton's major role in replenishing oxygen
in the atmosphere is something we've only fully grasped
with the help of satellites.
FELDMAN: Satellites gave us
that very first global picture,
global assessment of what the ocean's plants were doing.
NARRATOR: And what plankton are doing is providing life-giving oxygen
for us.
FELDMAN: Plankton in the ocean are responsible for over half
of the oxygen that we breathe,
and it's what most creatures on this planet rely on to survive.
NARRATOR: Microscopic organisms as well as rainforests
are the lungs of the earth.
So what other secrets of life can satellites--
our eyes in space-- reveal?
It turns out that another surprising way life is sustained
is through a violent force: lightning.
From orbit, the whole earth buzzes with electricity.
Astronauts are often amazed by the intensity
of the electrical storms raging far beneath them.
SELLERS: You can see a thousand miles' worth
of lightning flashes left and right as you're looking down,
and they seem to set each other off like fireworks,
bang, bang, bang, bang, bang.
It's really quite amazing.
NARRATOR: But to understand lightning's global impact,
we need more than just observation.
NASA's TRMM satellite carries a high-speed camera
that can detect individual lightning bolts.
From this information it's possible to build a picture
showing the distribution of lightning all across the globe.
Astonishingly, 40 strikes occur every second.
That's more than three million strikes a day.
So how is all this lightning created?
And what is the effect of all this energy
streaking through the earth's atmosphere?
Each day, the combined force of sunlight and water vapor
creates 40,000 thunderclouds.
The rising columns of moist air generate powerful updrafts
that turn water vapor into ice particles
inside the clouds.
As ice and water droplets smash into each other at great speed,
vast charges of static electricity build up.
An average thundercloud contains enough energy
to power a city the size of Denver for ten hours.
Eventually the charge builds to a point
where air molecules are torn apart
and a lightning bolt is born.
A bolt is no thicker than a human thumb,
yet it's five times the temperature
of the surface of the sun.
As it burns through the atmosphere,
the electricity breaks apart the molecules of nitrogen
contained in the air.
ADAMEC: A lightning stroke,
it actually splits the nitrogen
into single nitrogen molecules.
Nitrogen doesn't like that.
It's desperately looking for something
to connect back to with and it often does it with oxygen.
NARRATOR: When oxygen bonds with nitrogen,
it creates a vital nutrient called nitrate.
Satellites show the extent of nitrate--
simulated here in yellow--
produced by the more than three million lightning bolts
that strike every day.
This creates about 13,000 tons of nitrate.
It dissolves in water droplets in the clouds
and falls to the ground in rain.
Most people are familiar with nitrates
because they're fertilizers.
So when it rains in a thunderstorm,
in a way you're getting a free fertilizing,
because the water will have nitrates in it.
NARRATOR: Nitrate is absorbed through the roots of plants
and enters the food chain.
When we eat these plants, the nitrates become available to us.
And so this vital nutrient enters the cells
of every living organism on earth,
where it is critical for building the structure of plants
and helps make proteins and DNA in our bodies as well.
It is essential for the survival of all living things.
But nitrate production is not the only way
in which lightning promotes life on earth.
In the Canadian Yukon,
a massive wildfire devastates over ten square miles of forest
in less than a week.
Such blazes often start with a random bolt of electricity
from the sky.
In distant Siberia, over 1,500 square miles of forest
burn to the ground, sparked by a lightning bolt.
These flames may seem purely destructive,
but thanks in part to satellites,
we see that they can also be life-giving.
The Terra satellite can detect the location of every fire
on earth by looking at its heat signature in infrared.
SELLERS: Terra basically gives us a map of all the fires
in all the forests and grasslands of the world
every day.
NARRATOR: This sped-up visualization of Terra's data
shows a year's worth of fire all around the world.
The vast swaths of orange are actually thousands of tiny dots.
Each one represents a half square mile of land
where a fire has burned,
over 19 million square miles in total.
The Terra data also reveal fire's role in renewing life.
SELLERS: The observations have shown us
how important fire is as an element of change.
NARRATOR: The benefits of change can be witnessed
in the forests of northern Canada.
This is a vibrant forest,
but it has its share of dead and diseased trees.
Locked inside them are ingredients that are essential
for new life: elements like carbon, sulfur and phosphorous.
Yet in a cold environment like this,
trees take decades to decompose
and return these elements back to the soil.
Fire can shorten the cycle to a matter of hours.
The pine tree is highly flammable.
It's full of sap and resins that burn easily.
The oxygen in the atmosphere fuels the flames.
ADAMEC: When you're looking at fire,
you're looking at a rapid oxidation.
That's what fire is.
NARRATOR: Within a matter of hours,
what may have started as a spark from a single lightning bolt
turns acres of forest to flames.
The nutrients these trees have stored for so long
end up in the ash.
Fires also consume the dead animals
whose bodies litter the forest,
returning the nutrients they contain back to the soil.
The smoke climbs into the sky,
and the ultimate impact of this nutrient-rich ash
can eventually be seen from space.
With its infrared sensor,
Terra can pick out the heat given off by the leaves
of healthy new vegetation that grows after fire.
A pulse of new growth follows every blaze.
Huge areas of forest get burned down quite regularly
and they're followed almost immediately by rapid regrowths.
NARRATOR: In forests all over the world,
the data from Aqua and Terra show that within months,
large areas devastated by fire are rejuvenated.
From a global perspective,
wildfires are essential to the cycle of life.
Fire's like a great blender for all the materials
in the earth system, so when you get dead living material,
particularly in the forests,
fire will rip through there and decompose that stuff
very quickly into its basic minerals and compounds
that new life can use almost immediately.
NARRATOR: Fire is such an intrinsic part of nature
that many plants have evolved to make active use of it.
The pine tree drops its seeds in the ashen aftermath of a blaze
to make the most of the nutrients
that have been released.
Wildfires are essential to maintaining the health
of many of the world's ecosystems.
It's a mechanism by which
habitats that are no longer productive regenerate.
We can now follow this process over decades.
SELLERS: When you look 30 years of satellite data,
you see this continuous, dynamic rearrangement of the biosphere.
The nutrients that that tree has pulled up from the soil
are being dropped back down again on the soil
to feed the next generation.
The effect of all this is to allow the biosphere
to turn over far more quickly and efficiently.
NARRATOR: By looking at the world from orbit,
we see our home planet anew.
We discover countless hidden connections, all linked to life.
The circulation of weather and ocean currents
affects the ebb and flow of ice at the poles.
Originating in the earth's crust,
erupting magma interacts with cold ocean water,
producing nutrients that rise to the surface
and nourish aquatic life.
Eventually, airborne in dust,
nutrients travel around the planet,
finally enabling tiny plankton to fill the air with oxygen.
That allows complex animals like us to survive.
Oxygen also allows fire to burn,
which, in turn, accelerates the pace of death and rebirth
in the forest.
Above all, life's major driver
is the energy we receive from the sun.
As the earth rotates over 24 hours,
the planet responds to the incredible power of the sun,
our local star.
Each day more than a million terawatts--
over 7,000 times our global energy consumption--
strike earth.
This triggers a wave of activity around the globe.
At dawn, plants on land and plankton at sea
begin to photosynthesize and grow.
At the same time,
sunlight drives wind and weather around the globe.
We are also a part of this cycle,
as our bodies respond
to the daily inflow of energy from above.
Our skin cells use sunlight to create essential vitamins.
Even the flight paths of planes reveal our intimate relationship
with the rhythms of day and night.
Aircraft travel west in the morning to extend the day
and east in the evening to reduce the night.
But while the sun nurtures all life on earth,
it also has the power to destroy.
And with the help of a very different kind of satellite,
we are coming to understand just how great a threat it can pose.
Orbiting 22,000 miles above the earth
is the Solar Dynamics Observatory.
This satellite looks not at the earth, but away from it.
Its task is to observe the radiation released by the sun--
what scientists call space weather.
We have this wonderful new satellite
that is up in space, looking at the sun 24 hours a day
and is providing unprecedented images of the sun
and where space weather is born.
NARRATOR: These striking images are produced
by the SDO's ultraviolet sensor,
detecting light frequencies beyond the blue end
of the visible spectrum.
The sun emits constant light,
heat and other forms of radiation,
along with occasional dangerous bursts of charged particles.
GILBERT: Most people don't realize
that the earth is exposed to charged particles
that are constantly coming away from the sun
at about a million miles an hour.
NARRATOR: Sometimes a massive pulse of those charged particles
erupts from the sun's surface.
It's called a coronal mass ejection
and it contains billions of tons of charged particles
superheated to tens of millions of degrees
and blasted out at millions of miles per hour.
It has the potential to wreak havoc on our planet.
This supercomputer visualization shows what happens
when a coronal mass ejection occurs.
The explosion is equivalent to 14 million Hiroshima bombs.
It sends a cloud of charged particles millions of miles wide
racing towards earth.
Without some kind of protection,
these enormous blasts would strip away the atmosphere,
destroy our fragile ecosystems and scorch the earth.
Over time, repeated coronal mass ejections would even cause
the oceans to dry up,
leaving behind a planet as barren and bleak as Mars.
Fortunately the earth has an invisible shield,
a magnetic field that satellites are now enabling us
to better understand.
Orbiting between 40,000 and 120,000 miles above the earth,
NASA has a network of satellites called THEMIS.
Each is equipped with highly sensitive instruments
that can detect the strength of magnetic fields.
GILBERT: THEMIS is a series
of probes that are aligned along the earth's magnetosphere
and they detect variations in the magnetic fields.
NARRATOR: This computer model, using THEMIS data,
shows how an invisible magnetic force field
called the magnetosphere protects the earth.
It's generated by the rotation of the earth's core.
GILBERT: THEMIS allows us to build a overall picture
of the structure of the magnetosphere
and how it operates.
NARRATOR: THEMIS reveals how the magnetic field
is constantly blasted by the sun.
The wave of charged particles called the solar wind
distorts the magnetosphere into a gigantic teardrop shape,
120,000 miles across.
As wave after wave of solar particles
strike the outer magnetosphere, most are deflected.
But when a coronal mass ejection arrives,
it tears open the magnetosphere,
allowing a vast number of charged particles
to breach the magnetic field's first layer.
The particles are free to rush in towards the planet.
But the earth has a second line of defense.
Inner magnetic fields steer the radiation
down towards the poles.
GILBERT: This process is extremely energetic.
Particles get accelerated and then they travel down
along the magnetic field lines towards the polar regions.
NARRATOR: The radiation streams downward,
encircling both the North and South poles,
and triggers something we can see with our own eyes,
one of nature's true wonders:
the Northern and Southern lights, or the aurora.
As the radiation strikes the upper atmosphere
at extreme speed, it excites the air molecules.
This makes them glow.
The oxygen in the air radiates red and green.
The nitrogen, red and blue.
These charged particles that originated from the sun
get trapped and then interact directly
with the earth's atmosphere, causing these beautiful colors.
So when we're looking at the aurora,
basically we're looking at the fact
that the sun and the earth are intimately connected.
NARRATOR: The aurora is a vivid reminder
of how potentially lethal energy from the sun is dissipated
in the upper atmosphere.
The earth's magnetic field has shielded the planet
from the sun's deadly radiation for billions of years,
enabling life to take hold and flourish.
Satellites are revealing one final piece
of this incredible puzzle-- the role that humanity plays.
Our human footprint has grown so large
that we have become a major global force in our own right.
Our impact is the consequence of a system
that has created and sustained life
for three and a half billion years.
Our success as a species has resulted
in rapid population growth.
And today our presence can be seen
across 80% of the landmass.
Now we, in turn, are affecting the many natural cycles
that govern our planet.
Looking for signs of pollution,
the environmental satellite Aura's infrared sensor reveals
the atmosphere's chemical fingerprint
and shows us how we are affecting the entire globe.
We already manufacture more than twice the nitrate produced
by lightning, much of it used for fertilizer and explosives.
Our factories release more sulfur
than all the earth's volcanoes.
Our industry and transportation produce more carbon dioxide
than the Amazon rainforest captures.
Our cities generate dust,
trigger electrical storms and affect rainfall.
And these are just a few of our impacts
on earth's natural cycles.
Our earth is changing.
We're on a path to somewhere
and our ability to understand that path is crucial
to success in the future.
And satellites help us answer
some of the most fundamental questions
needed to understand how our planet behaves.
NARRATOR: But there is one key difference
between the impact of nature and our own.
Unlike volcanoes, the motion of ocean currents,
or the oxygen produced by forests and plankton blooms,
we make conscious decisions about what we do.
And here satellites are crucial once more.
The information they provide can help us meet
the challenges of the future.
SELLERS: The real power of satellite observations
is they represent objective truth.
They tell us about what the world actually is doing,
not what we would like it to be doing,
not what we might fear it to be doing,
but what it's actually doing.
And it's that that allows us to see change,
real change, for what it is.
NARRATOR: Satellites are telling us that the oceans are slowly warming.
In the past 30 years,
the average temperature of the ocean's surface has risen
by half a degree.
Models suggest this extra heat
could be increasing the intensity of hurricanes
and violent storms all around the world.
Satellite data shows that in Antarctica,
ice shelves that took many thousands of years to form
are collapsing year after year.
And in the Arctic, sea ice is diminishing at an alarming rate.
Many factors play a part in these dramatic changes,
but most scientists agree
that human activity through our release of greenhouse gases
is the main driving force.
All around the globe, satellites are recording change,
but there is a problem.
Just as we are able to capture and measure these changes,
many of the current fleet of satellites
are coming to the end of their lives.
Satellites need fuel to stay in their orbits.
When their time is up,
they must either use the last of their fuel to boost themselves
far away from the earth
or descend and burn up on reentry.
It's predicted that the number
of NASA's earth-observing satellite systems will go
from 20 down to fewer than ten within the next decade.
The constant stream of information
from these vital instruments in space will fade.
If we fail to replace these satellites,
we could lose our ability to track the web of connections
that is fundamental to life.
ADAMEC: The complex interactions would be absolutely invisible to us
without a larger view of the earth.
It's the consistency and the amount of data that they provide
that allows us to understand the processes that are going on
in the earth that are important to maintaining life
as we know it.
NARRATOR: Little more than half a century
after the birth of satellite technology,
we are still only beginning to realize its possibilities.
Our planet harbors mysteries beneath its white clouds,
blue oceans and verdant landscapes.
And they can only be solved with the help
of these eyes in the sky looking down at earth from space.
== sync, corrected by elderman ==
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