[volcano erupting]
- [host, Joe Hanson] It was one of the most cataclysmic
natural disasters in American history,
destruction on an unimaginable scale.
But today, Mount Saint Helens volcano
is experiencing a rebirth.
It's the site of Earth's newest glacier,
a glacier that is awe-inspiring from both above
and below.
Why are these scientists here?
Because they hope the secrets within these frozen caves
will help reveal the mysteries of far-off planets
in our solar system and beyond.
[upbeat music]
It's spring 1980.
Mount Saint Helens stands tall,
the fifth highest peak in Washington state.
But on the morning of May 18th,
all of that changes in an instant.
[volcano erupting]
The volcano explodes
with 500 times the force of the Hiroshima bomb.
It's the most destructive eruption in US history.
57 people and thousands of animals die.
230 square miles of forest are leveled.
Devastation is widespread.
The blast creates a yawning crater
about the size of downtown Seattle.
Not long ago, lava flowed through here,
but now this massive caldera holds something wondrous,
the world's youngest glacier.
It's known as Crater Glacier
and has largely remained out of sight of the public.
Even more surprising than its location on an active volcano
is the fact that the glacier continues to grow
while most others around the world are in fast retreat.
What's driving its growth?
To understand it,
you need to know how the crater formed.
The 1980 explosion caused the mountain's
north side to collapse.
What remained was a crescent-shaped husk.
The steep crater walls shade the glacier from sunlight
most of the year.
These walls are so steep, in fact,
that masses of snow, ice and rock
slough off the rim and pile at the base.
Combine that with a large annual snowfall
and it provides a steady diet of raw materials
to feed a hungry little glacier.
Over the decades,
this baby glacier grew into the Hulk it is today,
and it's growing in thickness by up to 15 meters per year.
This crater and its glacier
have become a scientific curiosity.
This international team of scientists
will spend a week up here researching it.
- [Andreas] This is a very, very special place,
to be in the middle of a crater which was a mountain,
and then you're sitting in the middle of it, that's awesome.
- [Joe] The glacier on which this camp sits
is more than 200 meters thick in some places.
That's close to the length of two football fields.
- [Kalind] It is definitely, definitely a dangerous place
where you constantly have to be vigilant.
We woke up one day and a crevasse was forming,
basically a break in the snow.
And we were worried our tent was just gonna go down
with some of the glacier.
- [Joe] Just getting to the research site
is an adventure.
Boulders thunder down the steep walls of the crater
with such frequency and speed
that one area has been dubbed the shooting gallery.
- [Carl] It's a little scary,
especially the first few times
while we were out on the glacier,
having the rocks come down.
- [Michael] It's an inherently dangerous place
so we have to carry a lot of safety gear with us.
And then we have to haul all the gear up a mile hike.
- [Joe] Although this glacier looks solid,
it's actually riddled with cavities.
These caverns are a sign that the volcano remains active.
Vents in the crater known as fumaroles
belch scalding hot steam and gases.
This hot steam and gas melts holes in the glacier.
- [Christian] The fact that they're caused by volcanic gas
and steam just makes them totally unique.
There's actually not many places like this in the world.
- [Roberto] There is only that we know of, for sure,
maybe four or five sites around the world.
- [Joe] Some of the caves can wind a mile or more
through the glacier.
Inside, it's an alien landscape of dripping ice.
- [Roberto] It's not a very welcoming environment.
You don't really know what's gonna happen
because there are dangers everywhere.
- [Andreas] Sometimes it's really foggy.
You don't know where you really are and where to go.
- [Christian] Nothing is stable in these caves.
So anywhere you step could be a boulder
that can roll down slope.
You could easily twist an ankle or hurt yourself.
And if you did, because of the difficulty of the terrain,
it would be very hard to get you out.
- [Joe] But to these scientists,
the opportunity to study this unique environment
is worth the risks.
Mount Saint Helens is the most active volcano
in the continental US.
And this glacier could serve
as an early warning system of sorts.
- [Andreas] This is a great laboratory up there
because everything what's going on under a glacier
is in a time-lapse.
So driven by the fumaroles, these caves are really active.
If the melting is getting stronger
and the glacier would retreat,
this could be a sign for the next eruption.
- [Joe] While Saint Helen's big features like glaciers
might hog the spotlight,
some of these researchers are focused on smaller mysteries.
- [Richard] I am an astrobiologist
and one of the things you try to do as an astrobiologist
is you try to find an analog here on Earth
that is similar to an environment in space.
Mount Saint Helens is a very extreme environment,
especially in these glacier caves because it's dark
and nothing has ever grown in these environments.
But this is a very difficult environment
for microorganisms live in,
and any kind of organism to live in.
- [Roberto] Mount Saint Helens is particularly unique
because it's a fairly new system.
The eruption in 1980 basically sterilized the volcano.
So anything that we find here allows us to look at the ways
that life can inhabit a new system.
- [Joe] In this blank slate of life,
they're finding extreme bacteria,
recolonizing and growing beneath the ice,
feeding off of the gases in these caves.
By learning about how the smallest forms of life
develop in extreme environments on Earth,
the scientists are hoping to gain a deeper understanding
of what to hunt for on places like Mars.
So by looking inward at this volcano,
we're actually looking out into our solar system.
- [Richard] The more we learn about these sort of systems,
the easier it will be for us
to explore surfaces of other planets.
- [Joe] Before you go, I want to tell you about
a new documentary series on PBS Voices,
American Veteran: Keep it Close.
Each episode tells the story of a US military veteran
and a special object they have from their time in service,
and how these mementos helped keep them grounded
through extreme circumstances.
Check it out at the link in our description
and let them know that Overview sent you.
[upbeat music]
♪