All language subtitles for How.The.Universe.Works.S09E05.Aliens.Of.The.Microcosmos.1080p.AMZN.WEB-DL.DDP2.0.H.264-alfaHD_track4_[eng]

The universe.

Vast, dynamic and explosive.

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.

We call this strange hidden kingdom
the microcosmos.

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.

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.

And it will influence our future
as we venture out into space.

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.

We share our world
with the microcosmos.

Will we coexist
in an uneasy peace...

..or will it destroy us?

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.

Maybe we ignore this other universe

because it's invisible
to the naked eye.

We live in a largely
invisible universe.

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

Some of the bigger 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.

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.

A century ago,
we faced the Spanish flu.

This absolutely annihilated Europe
at the time.

It caused million upon millions
of deaths.

So this is definitely not
the first pandemic.

It 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.

The microcosmos is complex.

While some parts kill us,
others keep us alive.

The 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.

The 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.

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.

Even though they're around one 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 neighbouring galaxy,

Andromeda.

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.

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
kinda 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.

And over 39 trillion
bacterial cells.

The average human
has more bacterial cells

inside their body

than their 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 realised

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?

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

and given me goosebumps.

And strangely enough,
one of them is viruses.

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.

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 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?

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.

Inside a host's body,

viruses latch on to
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 sailor level
horror movie.

This method of replicating
is chilling.

It doesn't answer the question of
whether they're alive.

That uncertainty may influence
our search for life in space.

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?

We don't know.

But space viruses could be a sign of
other extra-terrestrial life forms.

Viruses have to have a host cell
to replicate.

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

Viruses might lead us
to extra-terrestrial 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.

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.

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.

The idea of hitchhiking bugs
sounds a bit wild.

But we have found chunks of Mars
on Earth.

Perhaps these space rocks
brought life.

It's not completely ridiculous.

We know that rocks, for example,
could come form Mars

and land on Earth.

A giant asteroid impact on Mars

could blow shrapnel into space
that could land on Earth.

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.

The early solar system
was like a pinball machine.

Stuff was hitting,
knocking stuff off,

that would land somewhere
and knock stuff off.

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

travelling through our solar system
had some hitchhikers on board.

If there's some microbe
riding on an asteroid

that got blasted off of Mars,
I kinda 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.

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 around the galaxy on asteroids
poses a lot of different challenges.

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.

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 neighbour planet,

and then was transferred here
inside a meteorite.

Maybe we are immigrants from Mars.

Hitchhiking bugs
may have arrived on Earth

and kickstarted 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.

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 lynchpin
of every cell.

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.

The Rosetta Mission

found another building block
for life out in space.

A form of phosphorous
on the comet 67P.

This was astounding.

- Comet 67
- P 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.

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

So these forms of phosphorous
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.

The early solar system
contained many chemicals

needed for life.

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.

These discoveries not only show that
essential chemicals came to Earth,

but that they exist
throughout the solar system.

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.

We got evidence

for the widespread distribution of
these building blocks in 2017.

A strange space rock called Oumuamua
raced through the solar system.

The weird thing about Oumuamua

is that it's clearly on a trajectory
that came from deep space,

interstellar space.

That it literally came from
another star.

Even weirder, its colour.
Its surface is red.

And so that raised
a lot of questions

about what its composition could be.

And one possibility

is that it's actually filled with
organic materials

which tend to have those colours,

especially when exposed to
the space environment.

This suggests organic materials

may travel through
interstellar space.

I think it's entirely reasonable

that we could be getting
organic materials

that are the building blocks of life
from outside of our solar system.

There may be
a molecular transport system

throughout the galaxy.

We could be receiving stuff

from other bodies
in our solar system

and from bodies
outside our solar system,

because stuff is moving around.

Oumuamua is just
the tip of the iceberg.

There are probably
lots of interstellar visitors

passing through our solar system
all the time.

Comets and asteroids
may have brought chemicals

to kickstart 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.

How did the microcosmos
and life on Earth start?

Did asteroids and comets
deliver the building blocks,

phosphorous, 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.

The energy from the impact
breaks down and reforms molecules

into new compounds.

You can actually strip apart atoms
and molecules,

recombine them in more complex ways,

and make the stuff of life
in an impact.

Over millions of years,

complex organic materials
fill Earth's oceans.

Then, around 3.5 billion years ago,

the process that kickstarted life
began.

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.

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 phosphorous.

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.

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 are 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?

How can we investigate if viruses
helped life on Earth develop?

They don't leave many clues
about their past.

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."

We don't know when viruses entered
the evolutionary game of life.

Was it near the beginning
or a little bit later?

There is this crazy idea
that viruses

might actually have come first
in the tree of life.

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 three-and-a-half
billion year old oceans

formed a shell of protein
around some simple genetic material.

But did viruses evolve
before anything else?

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.

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 benefitted 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.

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.

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
widely different organisms

and therefore help drive
evolution itself.

Now, probably almost all of
these injections did nothing useful

and 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.

If virally-enhanced cells thrived
in the primeval oceans,

over time, they might have evolved
into more complex creatures,

and eventually into us.

What's so crazy
is to think about the fact

that we actually could 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 descendent from a virus.

Just coming from something
that simple

and evolving into something
this complex

is just a feat of nature.

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.

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.

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.

Planet Earth, 2.5 billion years ago.

The microcosmos
colonises Earth's oceans.

This is not a world
we would recognise 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.

It was just bare rock.

So, to think about it,

a human going back in time to visit
the really early Earth,

they would find
an utterly inhospitable planet.

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 spacesuit.

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.

But this tranquil existence
was about to change.

For a long time, conditions on Earth
were fairly static.

But then about two-and-a-half
billion years ago,

an evolutionary glitch
changed everything.

A clue to that glitch
rests in strange rocky mounds.

Stromatolites.

Stromatolites are almost like
microbial cities.

If you zoom down on to their scale,

you'll see layer
upon layer of bacteria,

almost like
the high-rise skyscrapers

of one of our cities.

The microcosmic high-rises
are full of cyanobacteria.

These bacteria can photosynthesise.

Photosynthesis is a chemical reaction

that takes place inside a plant,
producing food.

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

Two-and-a-half 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.

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 produce.

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

transforming Earth's atmosphere
over millions of years.

This by-product, oxygen,
is extremely toxic.

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.

The new oxygen builds 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've 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.

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 kickstart of energy

and gave 'em a huge advantage
over other organisms.

It supplied enough energy that
organisms could become more complex,

larger, multi-cellular.

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've been possible

without cyanobacteria.

Simple organisms
became more complex.

Single-celled creatures
became multicellular.

This gradual accumulation of oxygen
into the atmosphere of the Earth

was huge for the multi-cellular
animal and life explosion

that occurred as a result,

and was one of
the most important events

in Earth's history.

This would've been
a complete transformation

of the Earth's atmosphere
and physical setting.

This is when the green Earth
started to evolve.

The great oxidation event
changed the course of evolution,

leading to our complex world.

It is really hard to overemphasise
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.

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?

Siberia, present day.

Rising temperatures are melting
the Arctic permafrost

revealing land sealed under ice
for tens of thousands of years.

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.

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.

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.

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.

Bringing this ancient virus
back to life

was sort of waking up the undead.

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.

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.

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.

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?

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.

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.

These viruses could potentially be
a threat to us.

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
at 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.

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 that these were
outbreaks of anthrax.

The defrosted reindeer died
nearly a century ago.

The anthrax that killed it
was safely locked away in the ice.

The thawing out of regions
like the Siberian permafrost

could be almost like
the inadvertent opening

of Pandora's box.

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

It could be releasing
ancient preserved microbes,

bacteria or viruses
that have been laying dormant

for hundreds,
if not thousands, of years.

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.

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 neighbourhood?

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 ten movies
where people go to another planet

and some disease,
some alien lifeform,

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.

As we launch more and more missions
into space,

we risk sending Earth's microcosmos
with them,

endangering the health of
the solar system.

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.

It's serious because
we're looking at places like Mars,

like Titan, Saturn's moon,
like comets,

where life, or at least
pre-biotic life, could've existed,

or in the past, there could've 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.

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.

Is it possible that we've already
sent pathogens out among the stars,

hitching rides on our spacecraft?

We've sent missions to other worlds,

and it could be that
during those exploration periods,

when we didn't really understand
the microcosmos,

we have already sent bacteria,

we've already sent viruses
to those worlds,

so we could've already
infected them.

We are absolutely sure

that we have already delivered
some aspects of our own microcosmos

to different worlds out there.

Every spacecraft we send,

we cannot get rid of
every tiny little bacterium,

every tiny little virus.

Bits of us already are on Mars.

You're looking good.

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.

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.

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.

NASA does care.

Before launching a new probe,

a planetary protection team
deep cleans every inch.

You try to bake the space craft,
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.

It's even more difficult to kill
microcosmic stowaways

if they're travelling
inside an astronaut.

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 sterilise a human.
You can't remove all bacteria.

We have to realise that

we are bringing the microcosmos
with us.

And we may change worlds entirely
without even noticing it.

Planetary protection continues
once the mission has landed.

So, thinking about
planetary protection

means we really have to think about
our actions in a whole new way.

For example, if the rover
were to find a pool of water,

we really couldn't get that close,

because we could not guarantee
that even after all of this time,

there wasn't some kind of microbe

that could jump ship
into that pool of water

and then live happily on Mars
and reproduce.

Potentially our impact
could be absolutely devastating

on worlds that 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.

Humans bear a responsibility
for the safety of the cosmos.

Our track record on Earth
isn't good.

When we look at the pattern of
exploration or colonisation

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 colonise 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.

Our relationship
with the microcosmos is complicated.

It's killed millions of people,
but without it, we wouldn't be here.

This time we're living in

is really causing us to reflect on
the microcosmos.

And the better we understand
these micro organisms,

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

The coronavirus crisis reminds us

we need to respect the world
we cannot see,

and recognise 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.

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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