All language subtitles for How the Universe Works s09e04 Aliens of the Microcosmos.eng

ROWE: The universe...

Vast, dynamic, and explosive.

[explosion blasts]

But this huge cosmos,
with its billions of galaxies

and countless stars,

isn't the only one...
We share our lives with

another universe.

The world of the small,

of the viruses, of the bacteria.

ROWE: We call this strange
hidden kingdom the microcosmos.

LANZA: The microcosmos
is incredibly important.

Even though we can't see it,
it's everywhere.

It's almost like
another universe

or another world all in its own.

ROWE: It guided our evolution...

We wouldn't be here
without the microcosmos.

...and it keeps us alive.

The microcosmos
is responsible for

the very oxygen that we breathe.

ROWE: And it will influence
our future as we venture out

into space.

OLUSEYI: And if we were ever
to find a place where

there is life, potentially
a new microcosmos,

we would have no immunity
if they're bad.

ROWE: We share our world
with the microcosmos.

Will we coexist in
an uneasy peace,

or will it destroy us?

[explosion blasts]

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A strange invisible
assassin stalks its prey.

It attacks and hijacks the cell,

forcing it to produce hundreds
of new raiders.

This is what happens when
the microcosmos turns on us.

In 2020, we experienced
this invasion

of the body snatchers
first-hand.

A tiny virus caused
a global pandemic... COVID-19.

This pandemic makes
me see the world completely

differently, because there was
an invisible universe,

one that covers me and is
within me

that I pretty much ignored
for the most part.

ROWE: Maybe we ignore
this other universe

because it's invisible
to the naked eye.

PLAIT: We live in a largely
invisible universe.

We can't see everything
that's going on.

Some of the biggest stuff
we can't see very well,

and, in fact, a lot of the
littlest stuff we can't either.

Just because something
is too small to see

doesn't mean it's not important.

In fact, very, very tiny things

have a huge impact on our lives.

ROWE: Some of these impacts
are beneficial,

but they're overshadowed by
the devastating effects

of disease.

The longest-running conflict
that humanity has been

engaged in is that against

the microcosmos, our
long running battle against

the bacteria and viruses

that are trying to kill us.

ROWE: A century ago,
we faced the Spanish flu.

HOWETT: This absolutely
annihilated Europe at the time.

It caused millions upon
millions of death.

So this is definitely
not the first pandemic,

quite frankly, probably isn't
the last one.

In a way, the coronavirus has
forced us to come

to a greater understanding
of the microscopic world.

ROWE:
The microcosmos is complex.

While some parts kill us,
others keep us alive.

Microcosmos is important for
us to survive,

in order for us to do
all of the things

that our body does,
in order for us to live

and grow and thrive.

Our lives depend
on the microcosmos.

The air we breathe and
the surface of the Earth around

us has been profoundly
affected by the microcosmos.

ROWE: Three invisible
microcosmos operates

in every part of the world.

This world that you can't see
is everywhere,

from geothermal hot springs
to glaciers

to deep sea hydrothermal
vent systems.

ROWE: We have discovered
that every cubic foot of

Earth's atmosphere and its
oceans contain millions

of viruses.

There are more viruses here
on Earth

than there are stars in
the universe.

That's incredible.

ROWE: Even though
they're around 1/400th

the thickness of human hair,
stuck end to end,

all the viruses on Earth
would stretch

100 million light-years.

That's 40 times the distance
to our neighboring

galaxy, Andromeda.

RADEBAUGH:
That really makes us ask,

"Whose planet is this anyway?"

If you just added this up
by sheer numbers,

you would say,
"This is the virus planet."

ROWE: The microcosmos
has also taken over

our bodies...
We're only partly human.

The fact that so little of
my own body, of everyone's body,

is human cells
kind of leaves you wondering

what's the rest of it
made of, right?

It is astonishing that we
share our bodies with over

380 trillion viruses.

ROWE: And over 39
trillion bacterial cells.

OLUSEYI: The average human
has more bacterial cells

inside their body than there are
human cells inside their body.

So what are we really?

There are moments in the history
of science that I actually

remember where I was
when they happened... when,

for example, we detected
two colliding black holes

or something like that.

But another one was when
I realized that

almost half our body
is actually not human.

- I mean, that is crazy.
- For people that are

scared of bacteria,
that's a really interesting

thing to know, right?

ROWE:
Bacteria help us digest food,

produce vitamins,
and even influence our mood.

But what are they?

Bacteria are single-celled
organisms with a cell wall

and a central nucleus
containing genetic material,

RNA or DNA.

They can move
around and replicate.

Viruses are
completely different.

In the universe,

there are some mysteries that
have actually personally made

me kind of pause,

give me goosebumps,
and strangely enough,

one of them is viruses.

ROWE: The mystery is
how viruses can

have so much impact
on the world,

despite their tiny size
and apparent simplicity.

Most are just a strand of
genetic material,

sometimes encased
in a shell of protein.

I mean, compared to bacteria,

which behave kind of like
other normal cells that we're

used to, to some degree,
viruses are very strange.

We don't really
understand viruses.

We... we don't even know
if they're alive or not.

The question are viruses alive
is actually

more difficult to answer
than you might think.

What is the definition of life?

What does it mean to be alive?

ROWE: NASA's definition
of life is a self-sustained

chemical system
capable of Darwinian evolution.

Entities that feed
make energy and reproduce.

Viruses can't do that
on their own.

They have to have
a host cell to do that.

They have the genetic material
that they need,

but none of the machinery.

So they really have
to infect a host.

If not, they're useless.

ROWE: Inside a host's body,
viruses latch

onto the surface of cells

and then take control.

A virus's life cycle is
effectively to hack

another cell.

They have to inject that
genetic material

into a living cell.

And then the cell is hijacked
and starts making copies of

the virus.

Which then have to burst out
of this cell almost literally

like that gory,
grotesque scene in "Aliens."

They burst out from the inside.

That's like
a cellular level horror movie.

ROWE: This method of
replicating is chilling

and doesn't answer
the question of whether

they're alive.

That uncertainty may influence
our search for life in space.

BYWATERS: One of the interesting
things to think about is

if we found a virus on
another planetary surface,

would we classify that as life?

Would we say that
we have found life?

ROWE: We don't know,
but space viruses could be

a sign of other
extraterrestrial life forms.

BYWATERS: Viruses have to have
a host cell to replicate,

so if you find a virus,
in essence, you've found life.

ROWE: Viruses might lead us
to extraterrestrial life.

Now, new research suggests
that life

on Earth may have come
from space,

brought to us
in a cosmic bombardment

when our planet was young.

ROWE: We find the microcosmos
in every feature of Earth.

But where did this strange
kingdom of the very small

come from?

Some of its members are so
weird, they look like aliens.

Could they have come from space?

There's this idea that
microbes could have hitched

a ride on a chunk of an asteroid

that would fall to Earth.

HOWETT: They could form
on a different planet.

Something hits that planet.

The rock that
they're sitting on gets lifted

and then hits the Earth
as a meteorite.

ROWE: The idea of hitchhiking
bugs sounds a bit wild,

but we have found chunks
of Mars on Earth.

Perhaps these space rocks
brought life.

PLAIT: It's not
completely ridiculous.

We know that rocks, for example,

could come from Mars
and land on Earth.

A giant asteroid impact
on Mars could blow

shrapnel into space
that could land on Earth.

ROWE: To learn how we must
return to the early

solar system,
4.5 billion years ago.

Many infant planets orbit
a new star,

our sun... this infant
solar system is chaotic.

Collisions between planets
are inevitable.

OLUSEYI: The early solar system
was like a pinball machine.

Stuff was hitting,

knocking stuff off,
that would land somewhere

and knock stuff off.

ROWE: The young Mars is
in the line of fire.

It already has primitive
oceans and perhaps

primitive life.

A huge space rock smashes
into the surface.

We call the event
the Borealis Impact.

It blows quadrillion tons
of rock into space.

It's not crazy to think that
one of these chunks of

rock traveling through
our solar system has some

hitchhikers on board.

If there's some microbe riding
on an asteroid that got blasted

off of Mars, kind of
feel sorry for it, right?

It's just living there on Mars,

doing whatever little
Martian microbes do.

And then a giant impact
ejects this thing into space.

DARTNELL: In order to get
from one planet to another,

a cell would have
to run a gauntlet.

It's almost like winning
a survival game show.

You've got to survive being
blasted off your home world.

You've then got to survive
the interplanetary journey

inside a small lump of rock,

being exposed to the vacuum of
outer space, to cosmic rays,

to UV radiation,
being dried out and frozen.

So the idea of
moving life around

the solar system or through...
Around the galaxy on asteroids

poses a lot of
different challenges.

ROWE: Events like the Borealis
Impact ejected so much rock

from Mars, there were lots of
opportunities for hitchhiking

bugs to run
the gauntlet of space.

But could they survive
the journey?

To find out, astronauts on
the International

Space Station grew simple
bacteria outside in space.

After a year of being
in open space, miraculously,

some of these microbes survived.

It's incredible.
These microbes just could not

be killed, even though
they were in the worst possible

environment for life.

DARTNELL: The mission,
therefore, shows us that

life can survive
the environment in outer space.

Life could be transferred
between planets.

Maybe life did get started
on Mars,

on our next door
neighbor planet,

and then was transferred here

inside a meteorite.

Maybe we
are immigrants from Mars.

ROWE: Hitchhiking bugs
may have arrived on

Earth and kick-started
the microcosmos.

But now, recent studies of
meteorites suggest that

even if living microbes
didn't make the journey,

the building blocks
that made them did.

[explosion blasts]

In November 2019,
an international research team

found an organic molecule

called ribose in meteorites
that had crashed on Earth.

Ribose is a sugar.

It's a simple sugar,

but it is a sugar that is

absolutely crucial to all life
on Earth.

Ribose is the sugar that
makes up RNA, and RNA

sits right in the linchpin
of every cell.

ROWE: RNA is a simple form of

genetic material that controls
cellular function.

It's found in most
primitive creatures.

Finding ribose on a meteorite
is so important for us to

understand the origins of

the microcosmos,
because these are

the building blocks, these are
the things that it needs to

get started,

so understanding where these
building blocks come from

allows us to understand how
the microcosmos might have

evolved and started.

ROWE: The Rosetta Mission
found another building block

for life out in space...

A form of phosphorus
on the comet,

67P.

SHIELDS: This was astounding.

Comet 67P was formed at
the birth of the solar system,

4.67 billion years ago,

and it hasn't changed
since then.

It's a time capsule
from the birth

of the sun and the planets.

DARTNELL: And it's been in
the deep freeze ever since.

So these forms of phosphorus
that we found on comet 67P

tell us what was available at

the time the Earth
was forming and then

when life was getting started
on primordial Earth.

ROWE: The early solar system

contained many chemicals
needed for life.

BYWATERS:
It's an important discovery,

because it means
that these compounds

were around when
the solar system was forming,

so they would have been
readily available for life to

tap into and use to start
forming cellular structure.

ROWE: These discoveries not only
show that essential chemicals

came to Earth,

but that they exist
throughout the solar system.

LANZA: We tend to think of
the microcosmos as only

existing on Earth in the sense
that only Earth

has these building blocks,

but now, these new observations
suggest that a microcosmos,

at least the building blocks
for one, could exist

beyond Earth and throughout
the solar system.

ROWE: Comets and asteroids
may have brought

chemicals to kick-start
the microcosmos.

Now, explosive new research
suggests that

space rocks hitting Earth
did even more.

Could the violent
impacts themselves

have helped life get started?

[explosion blasts]

ROWE: How did the microcosmos
and life on Earth start?

Did asteroids and comets
deliver the building

blocks, phosphorus,

ribose, and other
organic compounds?

Or did they start life
in other ways?

New research suggests
the impact of crashing

space rocks could have provided
the spark for life.

The force of the impact
actually triggered the creation

of these molecules that are
the building blocks of life.

ROWE: The energy
from the impact breaks down

and reforms molecules
into new compounds.

You can actually strip apart
atoms and molecules,

re-combine them in more
complex ways, and make the stuff

of life in an impact.

ROWE: Over millions of years,

complex organic materials
fill Earth's oceans.

Then, around
3.5 billion years ago,

the process that
kick-started life began.

THALLER: Going back to
the origins of life on Earth,

it was a process... you began
with large molecules

that almost accidentally began
to make copies of themselves.

These became the first genetic
material... some of these larger

molecules bound together
and became the first sort of

protocells.

A protocell could represent

this earliest pre-life
stage of evolution.

ROWE: Protocells lack the full
chemical machinery of

modern cells.

They're a simple cell membrane
surrounding a glob of

genetic material like RNA,
built from ribose

and phosphorus.

Now you have a barrier.

Now you can actually control
which chemicals come into

the cell and which go out,
and you protect the genetic

code intact, inside the cell.

Once that happened,
evolution began to run with it.

ROWE: These simple cells
grew more and more complicated

until shazam,

you get all life on Earth...

All cellular life, anyway.

Unlike bacteria,
viruses are not cells.

Scientists debate if
they're even living things.

So how, then, do viruses fit
into the birth of life?

Viruses aren't really thought
of as playing a role

in our evolutionary history,

but we're just beginning to
understand that

that's simply not the case.

What if viruses themselves were

an essential cog in
the machinery of life?

ROWE: How can we investigate if

viruses helped life
on Earth develop?

They don't leave many clues
about their past.

BYWATERS: The hard thing
with understanding

the evolutionary history

of viruses is they don't leave
a fossil record.

There's no geology that we can
go back and dig up and say,

Aha! This is when viruses
first came about.

ROWE: We don't know
when viruses entered

the evolutionary game of life.

Was it near the beginning,
or a little bit later?

There's this crazy idea that
viruses might actually

have come first
in the tree of life.

THALLER: When you think about
the real origins of life,

it had to start with
something that simple,

something that was just
a molecule that could

start replicating.

A virus may be our best
example of that

transition from just
complex chemistry

to the beginnings of life.

In this scenario,
chemicals floating

in the 3.5-billion-year-old

oceans formed a shell of
protein around some simple

genetic material.

But did viruses evolve
before anything else?

BYWATERS: The flaw in the virus
first hypothesis is that

a virus has to have a host
organism to replicate.

So without a host,
how does the virus replicate?

And this is the question
we have to ask ourselves

when we think of viruses
coming first on

the evolutionary tree.

ROWE: Modern viruses can't
replicate without a host.

It's likely that ancient
viruses couldn't either,

but could early cells
and viruses have joined

forces in a way
that benefited them both?

Some new theories are
suggesting that viruses

and cellular life co-evolved and
actually helped each other out,

and potentially even helped
out the evolution of

human life.

ROWE: How did
this co-evolution work?

We know that viruses today
inject their genetic material

into cells to manipulate them.

Perhaps early viruses
manipulated the genes

of the first cells the same way.

Think of this primordial soup
and the genes, the RNA, that's

in this primordial soup being
swapped between organisms,

kind of like a swap meet.

You bring something
you don't need any more,

and you pass it along
to somebody else.

So in this way, organisms
sharing their genetic material

back and forth offers
a competitive advantage

to each one.

ROWE: The virus might
break off bits of

the host's genetic material
and mix it with their own.

When the virus attacks
another cell,

it could pass on the mixed
genes to its next host.

In this sense, then,

viruses help stir things up.

They shuttle genes
between wildly different

organisms and therefore help
drive evolution itself.

Now, probably almost all
of these injections did

nothing useful or maybe even
killed the cell.

But if one in a million
injection changed

something for the better,

made it more complex,
made it more able to survive,

then that cell reproduced
even more.

ROWE: If virally enhanced cells
thrived in the primeval oceans,

over time,

they might have evolved into
more complex creatures

and eventually, into us.

RADEBAUGH: What's so crazy
is to think about

the fact that we could
actually be descended

from viruses.

I am sure that a lot of
my genetic

code originally came from
the injection of a virus.

I love the idea that I might
be descendant from a virus,

just coming from something
that simple

and evolving into something

this complex is just
a feat of nature.

ROWE: Viruses played a major
part in human evolution.

Around 8% of human DNA came
from ancient viral infections.

In fact, without them,

we wouldn't be human.

BYWATERS: In our brains, we
actually have relic viral DNA.

So DNA that came from a virus,

but this helps us.

Without this, we don't think
we would have consciousness.

ROWE: We also think that viral
DNA helped us develop

an immune system

to fight off infection
and gave us the ability to

digest starch.

The microcosmos
has guided our evolution.

It even created
the air we breathe.

But in doing so,
it also triggered

the largest mass extinction
the Earth has ever seen.

ROWE: Planet Earth,
2.5 billion years ago.

The microcosmos
colonizes Earth's oceans.

This is not a world
we would recognize today.

If you were to travel back in
time, just on Earth, to see what

it was like 2.5 billion
years ago,

it would look really different
in many ways.

There were oceans, and they had
life in those oceans.

But there weren't any land
plants or land animals.

There was just bare rock.

So to think about a human
going back in time to visit

the really early Earth,

they would find an utterly
inhospitable planet.

LANZA: As a human, you'd be
out of luck because there was

no oxygen in the atmosphere
at that time,

so hopefully,
you brought a space suit.

ROWE:
The atmosphere was fine for

the billions of inhabitants
of the early microcosmos.

They were very slow-paced,
and they did

everything they did without
any oxygen in the air.

ROWE: But this tranquil
existence was about to change.

PLAIT: For a long time,
conditions on Earth were

fairly static, but then,
about 2.5 billion years ago,

an evolutionary glitch
changed everything.

ROWE: A clue to that glitch

rests in strange rocky mounds,

stromatolites.

DARTNELL: Stromatolites are
almost like microbial cities.

If you zoom down onto their
scale, you'll see layer

upon layer of bacteria,

almost like the high-rise
skyscrapers in one of

our cities.

ROWE: The microcosmic high rises
are full of cyanobacteria.

These bacteria
can photosynthesize.

Photosynthesis is
a chemical reaction that

takes place inside
a plant, producing food.

Today, it's an important part
of our planet's existence.

2.5 billion years ago,
it was revolutionary.

And it happened when ancient
cyanobacteria similar to those

in the stromatolites mutated.

This mutation
allowed cyanobacteria

to take the energy from
sunlight and use it to make

sugars out of water
and carbon dioxide.

ROWE: This gave cyanobacteria
a huge evolutionary edge.

They could now make more
energy for

themselves so they could grow
and reproduce faster.

For everything else,
it was a catastrophe.

It produced oxygen
as a waste product.

Oxygen was no use to them,
so they released it into

the air,
transforming Earth's atmosphere

over millions of years.

ROWE: This by-product, oxygen,
is extremely toxic.

THALLER: The reason oxygen is
so dangerous is that

it's very reactive.

It loves to combine
with everything,

so think about something
rusting... iron rusts because

oxygen is actually combining
with the molecules.

It's called oxidation.

So when oxygen was
first released,

it was tremendously dangerous.

ROWE: The new oxygen built up
in the atmosphere,

killing off species of microbes
everywhere on the planet.

Right when this happened,
you would have had

a mass extinction.

This would have been a global
mass extinction event.

This was an unprecedented
environmental disaster,

probably in the entire history
of the Earth up to that point.

And I'm not even sure
it's been paralleled,

even up to today.

This may have been the single

biggest catastrophe
in our planet's history.

This was the Great Oxidation
Event, and it changed

our atmosphere,
it changed our planet,

and it didn't just end there.

Something changed again.

Another mutation allowed some
of these bacteria to use that

oxygen in their own metabolism,

and that was a huge change.

ROWE: The ability to use oxygen
was an incredible leap forward.

The beauty of oxygen
is that it allows

the metabolism to process
nutrients much more rapidly.

It basically helps bodies burn
these materials so that

they can generate a lot more
energy a lot more quickly.

Organisms that figured out how
to use oxygen for respiration

ended up getting
a huge kick-start

of energy
and gave them a huge advantage

over other organisms.

It supplied enough energy that
organisms could become

more complex,

larger, multicellular,
really the tapping into

oxygen and being able to use
oxygen in our metabolism meant

that it was a game changer,

that we could evolve
in ways that never would

have been possible
without cyanobacteria.

ROWE: Simple organisms
became more complex.

Single-celled creatures
became multicellular.

SHIELDS: This gradual
accumulation of oxygen

into the atmosphere of the Earth

was huge for the multicellular
animal and life explosion,

um, that occurred
as a result and was

one of the most important
events in Earth's history.

BYWATERS: This would have been
a complete transformation

of the Earth's atmosphere
and physical setting.

This is when the green Earth
started to evolve.

ROWE: The Great Oxidation Event
changed the course of evolution,

leading to our complex world.

It is really hard
to overemphasize

the importance
of the microcosmos.

Just the fact that
I'm speaking to you,

I'm breathing in and out,

I wouldn't be doing that without

the tiniest organisms
on the planet.

ROWE:
The microcosmos gave us life.

Now, it could wipe us out.

Global warming is releasing

potentially lethal bacteria
and viruses.

Are we facing a microcosmic
zombie apocalypse?

ROWE: Siberia, present day.

Rising temperatures are melting
the Arctic permafrost,

revealing land sealed under
ice for tens

of thousands of years.

DARTNELL: As that permafrost
begins thawing out

and melting with climate change,

maybe that will release
pathogens that have

been locked up for potentially
thousands of years.

ROWE: In 2014,

researchers investigated
melting Siberian tundra,

a region larger than the USA.

I've seen a lot of science
fiction movies where scientists

are digging around in the ice
and find something bad

from a long time ago.

ROWE: Scientists took samples of

tundra soil to the lab
and examined the contents.

They found a frozen
ancient virus.

A virus locked in ice
from over 30,000 years ago.

Isn't this the start of,

like, every horror movie?
A scientist uncovers some deep

secret of nature and then just

open it up and unleash it
on the world?

ROWE: Just like in a B movie,

The team fed the virus to

living single-celled creatures
called amoebas

to see if the virus
still functioned

after being frozen for
thousands of years.

The virus woke up, attacked
the amoebas, and replicated.

BYWATERS: Bringing this ancient
virus back to life

was sort of waking up
the undead.

ROWE: Scientists had no idea how
this zombie virus would behave.

Something about it was
very, very different.

It was huge compared
to normal viruses.

It was substantially
larger than any

virus that we had seen before.

This is the Goliath of
Goliaths among viruses.

ROWE: So large it looks more
like bacteria than a virus.

We call these kinds of
giant viruses mimiviruses,

because they mimic
other creatures, like bacteria.

ROWE: One way the virus
mimics bacteria is

in the amount of
its genetic material.

It has 900 genes, eight times
as many as a regular virus.

SUTTER: Viruses are very simple.

They don't require a lot of
genes to function,

but this virus has more genes
than necessary.

What is it doing with
all these extra genes?

ROWE: We have now found
other mimiviruses.

20 years ago, we had no idea

that this complex type of
virus even existed.

We still don't know what
all the extra genes do.

This type of virus might even
be able to generate

its own energy,

making it closer to bacteria
than other viruses.

Because it has
so many extra genes,

this is a virus that is not
acting like a virus.

ROWE: We can't be sure how

the Siberian mimivirus will
behave if released,

and even if it only attacks
amoebas, there could be

other large, complex viruses
buried in the ice.

They may not be so safe.

We know that there are large
regions of

the Earth that are locked
in ice right now.

There could be viruses that
live inside that ice that if

the Earth gets too warm,
could reactivate.

And these viruses could
potentially be a threat to us.

ROWE: Recently, other
dangerous frozen zombies

have reanimated,
hidden in the dead.

We tend to think of people
who died in

the past as not being able to
affect us all, right?

They're gone,
their germs are gone.

Unfortunately,
this isn't exactly true.

So for people who are buried
in tundra that's been frozen,

they never really disappeared.

And now, unfortunately,
as the climate warms,

these tundra environments are
releasing frozen people

and animals who died thousands
of years ago.

ROWE: But it's not
the dead people and animals

that threaten us...
It's the microbes inside them.

In 2016, that threat became real

when another area of
Siberia thawed.

A 12-year-old boy died,

and dozens of people
needed medical treatment.

2,000 reindeer also perished.

The culprit?
Reanimated bacteria called

anthrax inside
a melting reindeer.

Anthrax is a common microbe
found in soil.

In medieval times,

sometimes farmers would come
back to find entire fields

of dead animals.

They didn't understand at
the time what was going on.

They attribute it
to cursed fields.

But we now know these
are outbreaks of anthrax.

ROWE: The defrosted reindeer
died nearly a century ago.

The anthrax that killed it
was safely locked away in

the ice.

DARTNELL: The thawing out
of regions

like the Siberian permafrost

could be almost like
the inadvertent opening of

Pandora's box.

Once you open it, you don't
know what's gonna come out.

DARTNELL: It could be releasing
ancient preserved microbes,

bacteria, or viruses

that have been laying dormant
for hundreds,

if not thousands of years.

LANZA: If these microbes
are actually very different

from what we have
on Earth today,

if we encountered these
microbes, it's not really clear

what would happen
with our immune systems.

You know, it could be
totally fine,

but it could also wreak
complete havoc on us.

ROWE: It's also not clear
if modern drugs would

help us beat any ancient
microbes we unleash.

Now, as humanity expands
beyond Earth to new worlds,

will we carry our microcosmos
with us into space?

Or have we already infected

our cosmic neighborhood?

ROWE: Space is no longer the
final frontier of the future.

We're already exploring
the solar system.

We've sent probes to the planets

and put boots on the moon.

Now, NASA plans to land
astronauts on Mars

by the 2030s.

As a science fiction nerd
myself, without even breaking

a sweat, I could name 10 movies

where people go to another
planet, and some disease,

some alien life form, is
unleashed on humans

and kills us all.

I think that has it
exactly backwards.

If we try to settle on other
planets, we have to be really,

really careful and really,
really think about

how we are affecting them.

ROWE: As we launch more and more
missions into space, we risk

sending Earth's microcosmos
with them, endangering

the health of the solar system.

LANZA: And if we find
a planet that actually has

its own biosphere,
that has life of its own,

we need to be very careful
about how we introduce

our microbes to their microbes,

because it could really be
catastrophic for them.

PLAIT: It's serious, because
we're looking at places

like Mars, like Titan,

Saturn's moon, like comets
where life or at least

prebiotic life
could have existed.

Or, in the past, there could

have been a much more
habitable environment.

So it's entirely possible
that we are polluting,

we are infecting these other
objects with our own bacteria.

ROWE: If we contaminate
a pristine world,

we won't know which microbes
were there first.

Our bugs could even kill off
the native ones.

It may have already happened.

OVER RADIO: You're looking good.

ROWE: The Apollo 12 mission
brought back bits of the lunar

robotic probe Surveyor 3
it found on the moon.

Analysis of the probe found
a bacterial contamination.

We don't know
where it came from.

PLAIT: If that thing was
infected before we sent it

to the moon, and it sat
on the moon's surface

for two years in
a vacuum, changing temperatures,

radiation from space,
that really is telling us that

we can infect other planets
and we should

take this very seriously.

SUTTER: We're ramping up
our space missions,

we're sending probe after probe

to planets all
throughout the solar system.

Taking care to not send
our own diseases out onto

other planets is something
we actually have to care about.

ROWE: NASA does care.

Before launching a new probe,
a planetary protection team

deep cleans every inch.

You try to bake the spacecraft,
you try to disinfect things.

You build everything and keep
everything within a clean room,

which has a pressure
that blows dust out.

Everybody wears what are
called bunny suits,

so nobody touches
anything directly.

But then,
that's still not enough,

because microbes are
incredibly hardy.

ROWE: It's even more difficult
to kill microcosmic

stowaways if they're traveling
inside an astronaut.

DARTNELL:
In the not too distant future,

we'll start sending not robot
explorers, not probes to Mars,

but people, an inherently
dirty, mucky organism

like myself.

You can't sterilize a human.

You can't remove all bacteria.

We have to realize that we are
bringing the microcosmos

with us, and we may change
worlds entirely

without even noticing it.

Potentially, our impact could
be absolutely devastating on...

On worlds that are either have
life or emerging life,

and so we just need to take
that responsibility seriously

and be careful with the way
in which we explore them.

ROWE: Humans
bear a responsibility

for the safety of the cosmos.

Our track record
on Earth isn't good.

RADEBAUGH: When we look at
the pattern of exploration

or colonization that we use as
humans, we are really invasive.

We see a lot of destruction
in our path,

and we have to wonder if that's
what we're going to do

when we start to really
explore and colonize

outside of Earth.

Like viruses,
we also insist on spreading.

We insist on spreading around

our world,
around our solar system.

There is a great chance

that we will cause utter
destruction wherever we go.

ROWE: Our relationship with
the microcosmos is complicated.

It's killed millions of people,

but without it,
we wouldn't be here.

RADEBAUGH: This time we're
living in is really causing us

to reflect on
the microcosmos, and the better

we understand
these microorganisms,

the better able we are to deal
with what's happening today.

ROWE: The coronavirus crisis
reminds us

we need to respect the world
we cannot see

and recognize
that the microcosmos is

every bit as important to us
as the greater universe.

It's so easy, especially
right now in history,

to hear the word virus
and think about how harmful they

are, how dangerous they are.

But remember that you are
actually a creature built

of viruses yourself.

As far as we know, we've never
been without the microcosmos.

Microbes were here before us.

They'll probably be here after
us, and we need them to live.

BYWATERS: The microcosmos...
It's absolutely essential.

We couldn't function.
We wouldn't survive.

We wouldn't be here without it.

But it's also our greatest ally,

and it's also
our greatest enemy.

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