Original subtitles

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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