All language subtitles for What.on.Earth.S09E04.1080p.DSCP.WEB-DL.AAC2.0.H.264-BTN_track3_[eng]

NARRATOR:
They're watching you.

More than 5,000 satellites
circle the Earth.

Every day,
they uncover new

mysterious phenomena
that defy explanation.

Discovered from the skies,

code of the Norse gods.

This is, without a doubt,
the strangest thing I've seen

in archaeology.

NARRATOR: Something big
and weird over Missouri.

If I was in St. Louis,
I would be worried

NARRATOR: And America's
toxic time bomb.

This place is so polluted
that even

the rabbit droppings are
radioactive.

NARRATOR:
Baffling phenomena.

Mysteries from space.

What on Earth are they?

**

**

Aerial archaeologists
take to the skies

over remote wooded hills
in central Norway,

an on-board camera fires

laser pulses at the ground to
produce a LIDAR image of what

lies hidden beneath
the icy landscape.

This LIDAR image
really reveals

some incredible structures
on the ground here.

RUBEN: We're seeing all
these strange formations,

circles and what look like
three-pointed stars.

The whole thing looks
so weird.

It looks like something out of
a cell biology textbook.

NARRATOR: The aerial image
has uncovered

dozens of structures
lost to history.

They're clearly manmade,

and so that makes me wonder,
how old are these things?

And who made them and why?

NARRATOR: Archaeologist David
Hill is heading to the site

to investigate.

HILL: I'm very excited
about the structures

that you can see on
the LIDAR image.

Some of them I really
can't explain.

I haven't seen them before.

NARRATOR: Hill thinks some of
the structures

in the image are longhouses,

timber buildings built
over 1,000 years ago.

It suggests the mystery shapes
our legacies of

the Norse warriors who rose

from these lands at the end
of the eighth century A.D.

I suspect
they might be Viking.

The thing that I'm really
unsure about, though,

is their star-shaped
formations.

I honestly don't know
what they are.

We seem to be
getting up to the site.

NARRATOR:
According to the LIDAR data,

deep beneath
this undulating land

lies a vast array of circles
and stars.

Absolutely fantastic.

Many,

many sites have been altered,
have been plowed over,

but not here.
What we're seeing is intact.

Several of the circular
structures are poking

through the Earth,

more evidence, Hill believes,
that this is a Viking site.

It seems to be quite
a well-defined ditch.

I think this is
a burial mound.

Ditches were very important.

They delineate the sacred area.

Within the grave mound,
it's the realm of the dead.

Outside, it's the realm
of the living.

So I'm now stepping into
the realm of the dead.

What we're seeing is a burial
site from the Viking period.

NARRATOR: The image suggests
this realm of

the dead contains the remains
of over 100 Vikings.

I can see 1, 2,

3, 4,

5, 6.

I can't even count them.

This site is incredible.

Fiercely pagan,

the Norsemen would often
cremate their dead in

the belief that the smoke
would carry them to

the afterlife.

For others,
burial mounds are

seen as gateways to
another world,

one inhabited by those
who had died before them

and the gods
they worshiped yet also feared.

HILL: What
these mounds represent is

the cosmology of the Vikings.

This is where the living

would commune with
the ancestors and the gods.

Wow! Look at that.

Up there on the ridge.

NARRATOR: Two carved slabs
of granite crown

the largest of
the burial mounds.

This is enormous.

Stone of this size would have

been certainly for somebody
very important.

NARRATOR: The Norsemen would
often inscribe

gravestones like this
with runes,

mystical symbols,
which they believed were

originally discovered
by the great god, Odin.

They could be used as a means
of communication between this

world and the next,
or as spells.

This stone was built to
convene with the gods,

the spirit world.

It was raised as a gift
to them.

NARRATOR:
According to Norse beliefs,

half the warriors killed in
battle go to Valhalla.

The rest head to Folkvangr,

ruled over by the goddess of
sex and war, Freya.

And recent research suggests
the Vikings' desire to appease

their gods as they prepare for

these journeys has its origins
in a really historical event.

JANULIS: We've got a lot of
tantalizing clues that

at the end of 535 A.D.,

there was a massive famine,

and millions of people died
all across Europe.

NARRATOR: Geological records
reveal that in that year,

dust from a massive volcanic
eruption plunges Europe into

months of darkness,

causing crops to fail
and killing

a third of the entire
population of Scandinavia.

All those natural
phenomena that

we today understand
by science,

back in the Viking age,

they would understand
by relating the gods to them.

NARRATOR: As stories of this
catastrophe are passed down

over generations,

it inspires the tales of
destruction and vengeful gods

that dominate Viking myths
and sagas.

JANULIS: In mythology, this is
described as Ragnarok

or the apocalypse.

And when that happens,
things go dark, and it takes

several hundred years for
the population to build back up.

NARRATOR: What puzzles Hill is
how the giant star shapes in

the image are connected
to the Vikings'

beliefs in their gods
and the afterlife.

This is, without doubt,
the strangest thing

I've seen an archeology.

I'm walking down one of
the arms of the star-shaped

structure --
remarkable.

Absolutely remarkable.

NARRATOR:
Hill knows that three was

a magical number
for the Vikings.

The arms

have to mean something.

Odin, the God who created

the first humans,
was one of three brothers.

And before the Viking
apocalypse, Ragnarok,

there were three winters
without summers.

NARRATOR: What's more, the God
Loki has three children,

Thor, three weapons,
and Fenrir,

the monstrous wolf of
the apocalypse,

is bound by three chains.

This is clearly a link
between the world in

which we live and the realm of
the gods.

What went through the...

the minds of the people
who built this?

NARRATOR: Coming up,
decoding the Viking cipher.

If I'm right, it connected
the Earth to the spirit world.

NARRATOR:
And teleporting ships.

They are 60 miles inland,
so why are they there?

NARRATOR: An aerial laser
survey in Norway

has revealed what appears to
be a vast Viking burial ground.

Mystery star-shaped structures
sit in its midst...

..perhaps symbolizing
the sacred number

three found in
Viking mythology.

David Hill is investigating.

I've just discovered

some images and some
documents that relate to

the burial, and this material
is absolutely spectacular.

NARRATOR: Hill has learned that
several years ago, a vessel

was recovered from a grave
near the star-shaped mounds.

It originates from
the northeast of England,

a favorite hunting ground
for Viking raiders.

Yet what puzzles
the archaeologist isn't where

the object comes from,
but its age.

HILL: This is actually very,
very interesting.

It was produced
at least 40 years before

the Viking Age began --
that I really wasn't expecting.

NARRATOR:
According to historical texts,

the Viking Age
begins in 793 A.D.,

when warriors attack
the Lindisfarne Monastery in

northeastern England.

They wrought
absolute destruction.

The monastery was burned
and broken down.

It's a complete bloodbath.

NARRATOR: A raid spurs a wave
of pillage and slaughter

through Europe's churches
and monasteries that will last

270 years.

Because the Vikings got such

a reputation of brutalizing
their victims,

the fear of them spread
throughout the land.

We see this appeal across
the Christian monasteries.

"Save us, oh, Lord,
from the Norsemen."

NARRATOR: The age of the vessel
is hugely significant,

because it means those buried
at the site played a key

role in the rise of one of

the greatest warrior races
the world has seen.

This means that they were out
navigating the seas

over 20 years before
the Viking Age officially began.

NARRATOR: The years leading up
to the Viking Age are shrouded

in mystery.

It is a time when much of
Scandinavia is ruled

by groups of warrior peoples
known as the Vendals.

JANULIS: The history of
the pre-Vikings is fascinating.

We don't exactly know what
was going on.

It was sort of a dark time,

not a lot of communication,
not a lot of travel.

NARRATOR: What is known from
historical records is that

the Vendals were renowned
horse-mounted warriors

and traders.

But during
the eighth century A.D.,

something happens,
which transforms

them into seafaring raiders.

The Vendals move
more than

25 to 50 miles away from home.

They are not adventurous.

But the Vikings, the very word
"vikingr" means

sea traveler and wanderer.

NARRATOR: Some academics believe
the Norsemen's transformation

was fueled by the desire

to protect
their pagan beliefs.

In the late eighth century, the
King of the Franks, Charlemagne,

is pushing his Catholic forces
into Scandinavia,

slaughtering thousands.

This propels the Norsemen to

seek Christian blood
and riches overseas,

aided by an unusual
climatic event.

It's called
the Viking Warm Period,

and a lot of the Arctic Sea
starts to melt,

and as a result,

the Vikings start
going further

and further away from land
in their ships.

They became the most
famous seafaring

pirates in the history of
the world.

HORTON: They extended
right away across Russia,

to Greenland, and eventually
into North America itself.

NARRATOR: Before embarking on
these long, perilous voyages,

the Viking warriors would need
all the protection and strength

their pagan gods
could afford them.

They must also prepare for

the afterlife should
they perish in battle.

For these reasons,
Hill thinks the three-limbed

structures likely represent

the most important and venerated
symbol in all Norse mythology.

If I'm right,

this makes the site very
sacred place for the Viking.

The number three has
special significance,

but the one I think that has
the most significance for

this site is the Viking
world tree, Yggdrasill.

It had three roots,
and it connected the Earth to

the spirit world.

NARRATOR: The great world tree,
Yggdrasill,

supports the nine realms
of the Norse cosmos.

It connects the mortal
and immortal worlds,

and its three routes are
pathways to Asgard,

the land of the gods

and Helheim, the underworld.

1,200 years after the Viking
age of plunder began,

these extraordinary ritual
structures are rediscovered

from the heavens,
surrounded by

the graves of the warriors
who once worshiped here.

I am convinced that this was
a site where the clan

convened with the gods

and their ancestors
and the spirit world.

But until a full
archaeological investigation

takes place, the stars are gonna
hold on to their secrets.

NARRATOR: Coming up,
Hitler's ghost ships.

HEIMLER:
These are giant.

Why are they here in
the middle of a field?

And a mutant craft
in the Mojave.

I'm no pilot,
but there seems

to be something wrong
with this image.

NARRATOR:
May 4th, 2018,

the WorldView-2
satellite scans

the province of North Brabant
in the Netherlands.

At first glance,
this aerial image

of the Netherlands looks like
regular farmland.

But zooming in,

there are unusual shapes
here in this field.

They definitely
look like boats.

It makes no sense at all.

NARRATOR: The ghostly vessels
are almost 200 feet in length.

These are not rowboats,
they're ships,

and if you zoom out
a little bit,

they are 60 miles inland.

So why are they there?

NARRATOR:
Anywhere else,

ships buried this far inland
would be an unlikely discovery.

But the unique geography of

the Netherlands makes it
a real possibility.

About a third of the Netherlands
is actually below sea level.

We know that huge amounts
of land reclamation

has taken place.

Dams were created to hold back

the North Sea,
and the land was drained.

And people are always finding
remains of medieval boats

that really sank out in
the open sea

in these open fields.

NARRATOR: Historic images of
the same location reveal

the mystery craft have
a different origin.

They appear for the first time
in aerial photographs taken

during the Nazi occupation of
the country

during World War II.

Another big clue is the fact
that, within the immediate

vicinity of these shapes,

there are craters, and that's
suggestive of it having been

a bombing practice range.

But it doesn't really
make sense.

I mean, I could think of
boats for targets,

but on the water
and not inland.

In the run-up to World War II,
the Netherlands attempts

to remain neutral
on and is ill-equipped

to resist
the Nazi threat,

possessing just one tank to
repel 2,400 invading German

war machines.

The destruction was total.

The victory was swift,
and it was astonishing.

CADDICK-ADAMS:
The battle is over

by the end of May 1940,
the Germans

have taken just days to
overrun the entire country.

NARRATOR:
Declassified Nazi files

reveal the role
the mystery ships played

in the extraordinary events
which followed.

MORGAN: After the 1940 campaign,
Germans began to

stage up for an invasion of
the United Kingdom.

WALTERS: Of course,
the British aren't gonna

roll over to Hitler,

so he's gonna have to do
the really tough job of invading

a massively strong
and well-defended island.

What Hitler's trying to do is
something that

hasn't succeeded since
William the Conqueror in 1066,

and that's what these shapes
and shadows are all about.

NARRATOR: In June 1940, Hitler
commences Operation Sea Lion,

the code name for his plan to
invade the island nation.

But Britain presents a very
different challenge from

the European countries who had

fallen so quickly to the Nazi
tactic of blitzkrieg,

or lightning war.

MORGAN: At the heart
of blitzkrieg

was the idea that
an attack would come

without warning
and would involve

the close coordination
of mechanized units on

the ground that could range
over vast distances.

Hitler's plans for invading
other countries

worked really well
across land,

but you can't drive a tank
across the English Channel.

NARRATOR: In order for Operation
Sea Lion to succeed,

Hitler plans to neutralize
the Royal Air Force and launch

an amphibious invasion of
England's south coast.

But the fuhrer
knows that Royal Navy ships

outnumber Germany's
2 to 1.

So if Germany is gonna
defend her invading fleet,

her aircraft have got to take
out the boats of the Royal Navy

that's gonna attack
the German fleet.

The Luftwaffe is the most
powerful air force in

the world,

but only around 10% of
the bombs they drop

hit their targets
and much less

against moving ones.

You gotta remember,
you are in a German plane

traveling around 200 miles
an hour,

shuddering and shaking
in the sky,

and you're trying to drop
a bomb on a boat no more than

the width of a couple of houses.

That is incredibly
hard to hit.

HEIMLER: In order for
Operation Sea Lion to work,

the Luftwaffe is going to have
to increase their accuracy on

hitting ships tremendously.

NARRATOR:
The Nazis' solution is to build

a replica harbor and ships
next to an inland airfield

and use it to prepare
the bomber crews for their

assault on the Royal Navy.

CADDICK-ADAMS: When we look
at the image closely,

there's a mock port there,

and there's actually two
submarines, as well, and this is

all being crafted
so they get it right,

but away from
the stress of combat.

NARRATOR:
Munitions cost money,

so practice runs are carried out

with concrete bombs filled
with phosphor.

They're exactly the same
size and weight as a high

explosive bomb -- when they drop
and they hit the target,

they crack open,
and the phosphor reacts

and sends off smoke.

NARRATOR: Yet the Luftwaffe
pilots never get

the chance to put
their training to the test.

During the Battle of Britain,
the Royal Air Force

deals a hammer blow
to Operation Sea Lion,

destroying 1,800 German planes

and killing 2,500 airmen.

WALTERS: There's no way
that you could

launch on invading force
across the channel

if the RAF and the Royal Navy
could just take them out.

It would be slaughter.

The English Channel would have
run red with Nazi blood.

NARRATOR:
Today, the ships remain as

a chilling memorial to the great
invasion that never was.

These are
kind of a metaphor, because

they're built at a time
when Nazi Germany had grand

ambitions, and all of those

grand ambitions would
ultimately fall into ruin,

sort of like these ships.

NARRATOR: Coming up,
the mystery mega plane.

This thing is super-sized.

It doesn't even fit
on the runway.

And the experiment
that changed the world.

This is not your ordinary
military site.

This place has
an extraordinary history.

NARRATOR:
January 9th, 2019.

Flying high above the barren
expanses of the Mojave Desert,

the GeoEye-1
satellite captures

something weird sitting
on a remote runway.

I'm no pilot,
but there seems

to be something wrong
with this image.

It almost looks like
two airplanes sort of

smushed together.

MORAN: It actually looks like
the love child

of, like, a 747
and a catamaran.

NARRATOR: Ken Joyce
scans the strange craft

using Maxar's SecureWatch
technology.

JOYCE:
I started to think that

this image had been
somehow manipulated.

I can see a single shadow
with two fuselages.

I don't think that it's
an error in the image.

I think that this is just
one giant aircraft.

NARRATOR:
Joyce's analysis reveals

the monster plane has
a 38-foot wingspan,

twice that of a 747,

And the largest in the history
of aviation.

KOUROUNIS:
This thing is super-sized.

It doesn't even fit
on the runway.

The wingtips extend
over the sides.

MORAN: It doesn't look
like it could be

a passenger plane or even
a cargo plane.

So what is the purpose of
this thing?

NARRATOR: Analysts turn to
historical aircraft designs

for clues to the monster
plane's purpose.

There's a really deep
history in aviation of

building gigantic aircraft

that push the limits
of what we think is possible.

And the most iconic of these
is the Spruce Goose,

built by the billionaire
Howard Hughes.

NARRATOR: The colossal 320-foot
wingspan Spruce Goose is

followed three decades later
by the Antonov 225,

which holds the world record
for the biggest ever payload,

280 tons, equivalent to
45 African elephants.

But the aircraft
in the image has

a very different design
from these monster planes.

The Antonov has a very large

fuselage to carry
large amounts of stuff.

When we look at our mystery
aircraft, it has two fuselages,

both of which are very skinny.

It looks more like it's built

to carry something
underneath the aircraft.

NARRATOR: Experts consider
if the plane's location

could shed some light.

KOUROUNIS: This is
the Mojave Air and Space Port

in California --
this is a facility that's used

to test all kinds of
experimental spacecraft.

LINSELL: And that gives us
a clue that this plane

is probably designed
to haul rockets

into the air
and then launch them into space.

NARRATOR: By carrying a rocket
between the two fuselages

and launching it high up
into the atmosphere,

engineers could solve
a problem that has plagued

the aerospace industry since
before the Apollo program --

how to reduce the cost of
reaching orbit.

The United States spent
tens of billions of dollars on

the Apollo program,

and if you count for
inflation today, that would be

hundreds of billions of dollars.

NARRATOR: To get the Apollo
astronauts into orbit,

their Saturn V rocket
burns a large

swimming pool's worth of fuel
every nine seconds

to reach speeds four times
faster than a bullet.

And even today,
it costs $10,000 to

get just one pound
of payload into orbit.

KOUROUNIS: Any edge that
the aerospace industry can get

in terms of getting
payloads up,

out of our atmosphere
and into space,

whether it's people,
satellites, who knows what,

well, that's the Holy Grail

of the space industry.

The plane in the image,
called

the Stratolaunch,
is custom-built

to overcome this challenge.

MOSHER: The airplane
takes off from the runway

with the rocket in the middle,
goes up to altitude,

drops the rocket, which then
fires and takes a payload

all the way to orbit.

LINSELL: If you launch
the rocket from high altitude,

the air resistance
is much lower,

and this means that
you need less fuel,

and the rockets
can therefore be cheaper.

NARRATOR: The Stratolaunch's
maximum take-off weight is

1.3 million pounds, the same
as 110 Apache helicopters.

To carry a rocket
towards space,

it needs six turbo fan jet
engines and wings so big

they're nine times
the distance

of the Wright Brothers'
first flight.

This airplane is
so mind-bogglingly large,

they had to create
a custom-built hangar

to just house the thing.

The megaplane requires
a two-mile-long runway to

get airborne.

By carrying a rocket to 35,000
feet before releasing it,

engineers hope to reduce
the cost

of getting hardware
into orbit by 50%,

transforming the future of
space travel.

It's very rare that we catch

a glimpse of
this extraordinary plane,

and there's a bit of,
I guess, poetic irony

if you consider that we're
looking at something from space

that one day could bring us

into space and give us
that seemed vantage.

NARRATOR: Coming up,
the long-buried secrets

of the Manhattan Project.

What we're actually looking at
here is a nuclear graveyard.

NARRATOR: And the invisible
monster blob.

Something seems to be moving
across the terrain,

but nobody can see it.

NARRATOR:
July 31st, 2019 --

flying over
Washington State,

an aerial survey plane
scanning the 600-square-mile

Hanford military facility
captures something out of place.

Sitting right in the middle,

there is some kind of strange
arrangement of objects.

These structures are almost
like the keyboard

on the computer.

NARRATOR:
The weird keyboard consists of

more than 120 monster barrels,

each 40 feet long
and 30 feet wide.

These barrels are literally
the size of a house.

They appear to be storing
something, but what could it be?

NARRATOR: Elsewhere, a line of
supersized storage cylinders

would be a strange anomaly,

but because this is Hanford,
they could be evidence of

something much more disturbing.

This is not your ordinary
military site.

This place has
an extraordinary history.

Some say this is actually
the most polluted place

in America, so maybe this
has something to do

with these shapes
we're seeing in this image.

NARRATOR:
Declassified government files

reveal that
Hanford's deadly legacy

has its origins in
the most secretive and pivotal

military experiment of
the 20th century.

It was actually established
in World War II as part of

the Manhattan Project.

That was the U.S. development

of the world's
first nuclear bomb.

It was here that the world's

first big nuclear reactor
was built.

NARRATOR: Such is
the secrecy surrounding

the Manhattan Project that of
the 120,000 people working

on it, less than 1% know that
they are developing the most

catastrophically powerful
weapon in history.

ANNOUNCER: At Hanford,
Washington, is produced one of

the explosive materials
used in the atomic bomb.

[explosion blasts]

It's the same plutonium
that ends up going into

the Fat Man atomic bomb that's
dropped on Nagasaki.

So you cannot overestimate
how important this site is.

NARRATOR: During the Cold War,
the military installs

an additional eight atomic
reactors at Hanford,

which produce enough plutonium
to arm 60,000 nuclear weapons.

More than 56 million
gallons of

toxic waste seeps into
the soil,

enough to fill 85
Olympic-sized swimming pools.

This place is so polluted that

even the rabbit droppings
are radioactive.

So maybe these giant
cylindrical barrels are

a way of storing
this radioactive waste.

NARRATOR: Journalist Carlo Munoz
suspects the giant

cylinders are part of
a cleanup program,

but one dealing with radiation
from an unexpected source.

MUNOZ: If you count
the number of structures,

it's about 120 -- now,

interestingly enough,
the United States has

decommissioned roughly
120 nuclear submarines.

NARRATOR: The size of each
giant cylinder also

corresponds to that of
a submarine's nuclear core.

For all the benefits of
nuclear submarines,

their service life really
runs about 25 to 30 years.

At that point, they have to
be decommissioned.

The problem with that is,

what do you do with
the nuclear core

used to power these boats?

NARRATOR: It's a challenge
that has been facing

the military since 1959,

when they decided to replace
the nuclear reactor on the

USS Seawolf.

The Navy's solution is to
simply tow the old reactor

out to sea and drop it to
the ocean floor.

And you don't even have to be
the most concerned

environmentalist to think that
could be a really bad idea.

You're gonna slowly turn

the world's oceans radioactive
with obviously

devastating consequences.

LINSELL: Pressure mounted
to find a better solution,

and the practice was
eventually banned,

and what replaced it
was this facility at Hanford.

NARRATOR: Before the cores
arrive at Hanford,

the Navy begins
the decommissioning process

at the Puget Sound
Naval Shipyard,

160 miles to the west.

They basically take the sub
out the water,

and they chop it like
a sausage into three.

You've got the middle section,

which is gonna house
the reactor.

That's the bit you've gotta deal
with in order to make it safe.

The first thing
they do is remove

the actual nuclear fuel rods
from the reactor core.

Then you have what's left
is the reactor core itself.

NARRATOR: The core's medals,
after years of

neutron bombardment,
are still highly radioactive.

After arriving at Hanford,

the cores are lined up at
the site in the image,

code-named Trench 94.

What we're actually looking at
here is a nuclear graveyard.

At some point,
the U.S. government

is going to have
to bury this

in order to prevent nuclear
radiation from seeping out.

NARRATOR: When buried, these
barrels will join 24 million

cubic feet of radioactive
waste already entombed

at Hanford,

enough to create
1,800 bombs the size

that destroyed Nagasaki.

They claimed that
this is a safe way

of storing and getting rid of
nuclear waste.

But we've seen accidents
happen in the past.

For now,
the only thing we can do

is cross our fingers and hope
that nothing happens.

NARRATOR: Coming up,

a monster over the Midwest.

We're having some kind of
an explosion out of the central

St. Louis area.

NARRATOR: Satellites play
a vital role in

tracking severe weather
systems around the globe.

By combining
their data with

the technology known
as Doppler radar,

meteorologists create images
that map the speed

and intensity of
an approaching storm in

astonishing detail.

Doppler radar works by sending
pulses up into the atmosphere

and seeing whether the pulses
bounce off anything

on their way.

CERVENY: Doppler radar is
a fascinating tool

for meteorologists,
because it becomes almost

an X-ray machine that
we can use to examine

the inside of storms.

NARRATOR:
On September 19th, 2014,

Doppler data captures
what appears to be

a colossal weather front in
the skies over Missouri.

It almost looks like
we're having some kind of

an explosion
that is taking place

out of
the central St. Louis area.

If I was in St. Louis,
I would be worried.

NARRATOR:
The blob's location fuels fears

that the city's 300,000
inhabitants are about

to face the wrath of one of
the planet's most destructive

weather phenomenon.

Missouri sits in
the middle of several

states that comprise what's
called Tornado Alley.

That's where most of
the tornadoes

in the U.S. take place.

NARRATOR: Yet accounts from
local residents reveal

that the mystery blob is
no tornado.

Here's the weird twist.

There's absolutely no reports
of any bad weather in the area.

Something seems to be shifting
and changing and moving across

the terrain,
but nobody can see it.

So what's going on?

NARRATOR: Biologist Adam Ruben
studies the data in more detail.

The low signal strength shows
that we're dealing with a mass

of very small things,
all moving together.

Things seems like it has
to be some kind of swarm.

NARRATOR: If this is a swarm,
it's a monster,

around 300 miles wide.

Ruben thinks the images have

captured one of the most
incredible events in nature.

RUBEN: Not only is Missouri
right in the middle

of Tornado Alley,

it's also on the path of
one of the most impressive

migrations of any animal on

the planet,
the monarch butterfly.

NARRATOR: Every fall, vast
numbers of the monarch butterfly

migrate up to 30 miles
southward across the U.S.

to escape the freezing winters
of the Great Plains and Canada.

These amazing insects
travel all the way down

to Mexico on wings that are
thinner than paper.

The monarch migration is

the longest insect migration
in the world.

It is truly remarkable.

NARRATOR: The monarch butterfly
has a bizarre life cycle.

Between April and September,
four generations

of the critters live and die

in their North American
summer homes.

But as winter looms,
something weird happens.

Most monarch butterflies,
when they emerge from

the chrysalis,
live only 2 to 6 weeks.

But there is this super
generation of monarchs that

live up to eight months,

and these ones make
this annual migration.

NARRATOR:
Triggered by decreasing

day length and temperatures,

the super generation head
towards the Mexican border,

covering up to 100 miles a day.

SCHUTTLER: They're traveling
from one end

to the continent to the other.

This would be
a long flight for us,

even on an airline,
and these are just

these little tiny insects.

And they're making it
all on their own.

NARRATOR:
Flying up to two miles high,

battling storms, predators,
and starvation,

it takes months to reach
their destination,

but for those
that make it here,

the danger is far from over.

RUBEN: Monarch butterflies
face a lot of threats,

but there's a new one that's
a little bit unexpected.

Monarch butterflies are being
killed by Mexican drug cartels.

NARRATOR: Before flying back
to North America in the spring,

the monarchs spend five months
clustered around oyamel

fir trees in the mountains of
Central Mexico,

and that puts them in
the firing line

of the local narcos.

The butterflies specifically
need the trees in this one place

in Michoacan province,

and the drug cartels have
moved in, because the wood in

these forests has become
incredibly valuable.

SZULGIT: Drug cartels are
branching out now into other

illicit activities,

be it kidnapping, land theft,
illegal mining,

and now, illegal logging.

[chainsaw revs]

In Mexico alone,
illegal logging is worth

$15 billion a year
to criminal enterprises.

After slaughtering
an estimated 150,000

people over the past
two decades,

the cartels may be about
to add

another grim statistic to
their reign of terror.

If you destroy
the wintering range,

the fate of the monarch
butterfly is

basically doomed throughout
much of North America.

RUBEN: There's that old saying
that if a butterfly flaps

its wings in Central Park that
there's snow in Siberia.

But what if millions
of butterflies

all stopped flapping
their wings?

We don't know
what could happen.