Original subtitles

Earth.

Over 8 billion people live here, but not all of them are home.

Since the turn of the century, a few have been living here.

In the most hazardous scientific outpost ever built.

The International Space Station.

Altogether, over 280 people have ridden a controlled

explosion 250 miles into space,

risking their lives to maintain a continuous

human presence off planet.

One day, we may be getting ready for a spacewalk,

and the next day we were doing some world class science.

Its unique environment provides a research laboratory like no other.

But conducting science in space brings its own challenges.

Very quickly, you can have an out of control situation

from a very innocuous start.

As astronauts push the boundaries

of science and exploration, they face daily threats.

You are constantly at risk of dying for a multitude of reasons.

You've got orbital debris that can hit your module and put a hole in it.

In the military, we say that problems happen at the fold of

a map and at night.

And that's exactly how this was shaping up.

How do we respond to that unknown?

Understanding situations may have the ultimate consequences.

This is the story of innovation

and scientific exploration aboard the ISS.

June 2024.

The world is gripped by a drama playing out far above Earth.

NASA astronauts Butch Wilmore and Suni Williams

had been scheduled to spend just eight days aboard

the International Space Station while testing

a new commercial spacecraft, the Boeing Starliner.

Into the spacecraft.

Instead, when the vehicle encounters technical issues,

their mission stretches into months.

Despite the difficulties, the pair pivots

to become routine crew members,

drawing from their years of training

and a deep love of the job to embrace their extended mission.

Because this job is like no other.

We're still pioneers in space,

so there's still a lot that we have to learn.

Space is incredibly risky.

The safest thing to do is to not go anywhere.

But that's not going to really teach you much

about your species or the planet you live on.

You have to take risks to get reward.

Butch and Suni's extended stay is just the latest in a long

line of unexpected challenges faced in orbit.

Since the space station's first module

was launched in 1998,

there have been countless moments of risk and uncertainty.

Requiring calm and quick thinking to resolve.

All to create a unique research laboratory,

a platform for international science and discovery through cooperation.

Uniting humanity in the pursuit of knowledge beyond our planet.

From monitoring hurricanes on Earth to cultivating plants in space.

From detecting X-rays released by neutron stars

to developing cancer therapeutics.

We have taken technologies, people, systems from all over the world,

and we've put it together into this amazing laboratory.

The research that we've been able to do has directly benefited

life on planet Earth, and we're only just getting started.

Every minute of an astronaut's day on the station is carefully planned,

and life on board might even come to feel routine.

But it's always just a matter of time

before the universe finds a way

to remind the crew of just how vulnerable they are.

In 2013, plans are underway to further extend

the International Space Station's scientific footprint.

A new module called Nauka, Russian for science,

is to be added to the station the following year.

Created to conduct materials science and biotechnology research,

Nauka includes a base for the European robotic arm,

and will also feature a specially designed airlock

to carry out experiments in the vacuum of space.

But to unlock this groundbreaking science,

astronauts must brave the most unforgiving extremes.

In my personal operational experience in the military,

in the Seal teams, the bad guys were the enemy

that's shooting at you.

In a space mission, the bad guy is the environment.

The environment is trying to kill you.

Space is not really made for life.

It's very cold and very hot at the same time.

It doesn't have an atmosphere.

It really doesn't want to keep you alive.

A spacewalk, also known

as an extravehicular activity or EVA, is especially dangerous.

Astronauts usually go through the airlock in pairs

so that once outside, they can assist each other if needed.

But still, they are isolated and vulnerable

to hazards like radiation,

micrometeoroid impacts, and equipment malfunctions.

On July 16th, 2013,

American astronaut Chris Cassidy and flight engineer

Luca Parmitano donned their spacesuits.

Spacewalks are not something that you just willy nilly do.

Hey, it's Tuesday. You want to go out and knock out a spacewalk?

No, it doesn't work like that.

It takes about four hours to go through

the oxygen pre-breathe process and all of the checks.

Leading up to opening the hatch.

All spacewalkers are tethered to the space station with a retractable

metal cable that pays out to 85ft.

And just like if you walk a pair of dogs on dog leashes,

those leashes get all tangled up.

On my waist.

Safety tethers are no different.

So oftentimes we intentionally take separate routes

so the safety tethers don't tangle up on themselves.

Luca and Chris come together on top of

the tranquillity module to carry out their task.

Connecting data and Ethernet cables for when the new module arrives.

38 minutes into the EVA,

a warning alarm is triggered in Luca Parmitano's spacesuit.

The carbon dioxide levels are too high.

Ordinarily, exhaled carbon dioxide would be controlled

and removed by the portable life support system

in Luca's backpack.

The alarm could signal a dangerous build-up of the gas inside

his spacesuit, which could lead to severe headaches,

impaired judgement, and even death.

We have a checklist telling us to check different parts of the suit,

to understand whether it is an actual alarm,

or whether the sensor itself is at fault.

It said, did the reading go from normal to ludicrous instantly?

If that happened, then it's probably the sensor's bad.

Doubtful of the carbon dioxide reading

and satisfied that Luca has no symptoms,

mission control concludes

that the sensor is faulty and the EVA can continue as planned.

But six minutes later, Luca calls mission control again.

There's another issue.

There should never be any water inside your spacesuit,

especially not in the helmet area.

And so I communicated that to the ground and I said,

I don't think it's a big deal.

I just wanted to keep going with the EVA.

On Earth, water falls under the force of gravity.

In space, it's much less predictable.

It's surface tension that drives the behaviour of water.

That surface tension is a pretty strong force.

And the water just wants to stick to whatever it's stuck to.

In Luca's case, the unexplained

ball of water is sticking to the back of his head

and threatening to creep around toward his face.

My biggest concern was the water getting inside my ears,

because if it did, it's really hard to get it out.

You cannot tap your head. There's nothing you can do.

I finished what I was doing and got over close to him,

and I remember I could see it looked like half of a grapefruit

just kind of jiggling on his head.

And then little bitty pieces of water droplets moving around inside.

At the European Space Agency,

astronaut instructor Herve Stevenin watches a live feed of the mission.

But the situation doesn't improve.

More water collects in Luca's helmet.

The LCVG, or liquid cooling and ventilation garment

circulates cold water in the spacesuit

via a system of tubes

to prevent astronauts from overheating.

As Chris and Luca correctly suspect,

Luca's LCVG has malfunctioned and is leaking water into his helmet.

The very suit designed to protect him from the dangers

of space may now be putting him in mortal danger.

That's the moment, I think, where it solidified in everybody's mind.

Okay, we're done for today.

Mission control terminates the spacewalk.

Luca needs to get back inside

the space station and remove his helmet.

He begins retracing his route back to the airlock

while Chris clears away their tools.

I remember leaving Chris

and as I made the corner and disappeared from sight,

I remember thinking that I really wished

that Chris could come with me because that's how we train.

We train to be together.

That's why we go outside as a team so that we have each other's back.

Before I saw Luca disappearing behind the Z1 truss...

..and I wanted to say outloud, Luca, stop!

Hold on, I'm coming with you.

It just felt like that's what we should do.

But as tempting as it is to hurry, Chris follows orders

and forces himself to move deliberately.

In the military, we say that problems happen at the fold of

a map at the junction of grid squares and at night.

And that's exactly how this was shaping up.

As soon as he started to move, the sun set.

And everything turns gold. Bright gold for one split second.

Incredibly beautiful. And then it's lights out.

The ISS takes around 90 minutes to orbit the Earth.

For half this time, the space station is in total darkness.

Now, once Luca started to move.

Well, what happened to his motion?

It gets transferred into the water too.

So that stationary, jiggly ball of jello

starts flushing around his head.

I felt it coming closer and closer to my forehead and I thought,

okay, this might cover both of my ears at the same time.

Maybe more than a simple hindrance.

It may be an actual problem.

When I just completed a manoeuvre where I put myself upside down.

So all my terms of reference had completely switched 180 degrees.

That's when the water really completely covered my nose.

And I found myself isolated, unable to see anything,

unable to breathe through my nose.

I didn't really know how much time I had

before the water reached my mouth.

If too much water covers both Luca's nose and mouth,

he'll be unable to breathe or drink his way out of trouble.

And to make matters worse,

water enters Luca's comms, causing it to malfunction.

My memories are of just trying to feel around making sure

that I would grab the correct handles in a pressurised glove,

which gives you no feedback, no tactile feedback.

And I called Chris, telling him, Hey Chris,

I think I'm a bit lost, but nothing came out

and I didn't have any return in my earphones,

so I knew that he couldn't hear me.

And at the time my thoughts were, okay,

um, I don't think Chris is going to come and get me right away.

How much time do I have? That was my thought in my head.

How much time do I have

before this helmet fills up with water?

There was a risk that if the water increased dramatically,

I would drown in space.

For the next five minutes,

Luca will be completely silent and alone.

He had the amazing presence about himself

when everything kind of went dark and silent to just stop.

At that point,

Luca remembers he is tethered to the space station's airlock.

That tether has a little 3 or 5Ib pull to it,

and he waited to feel the direction of that pull.

And then he just put his hand over and grabbed the next piece of metal

that he could find, and inched his way back that way.

Unbelievable awareness by Luca.

The gentle tug of the waist tether leads Luca back to the airlock.

But he's not safe yet.

Before he can take his helmet off,

the airlock must be sealed and repressurized.

With no time to waste, the ISS crew runs through their checklist.

Five minutes later, Chris joins Luca, squeezing in feet first.

The only thing that mattered at that point

was the hatch being closed,

because if we couldn't close the hatch,

we couldn't get good air pressure.

If we couldn't get air pressure, we couldn't get Luca's helmet off.

And if we can't get Luca's helmet off,

pretty soon, he's not going to have air in his helmet to breathe.

With Luca's comms malfunctioning and water now obscuring his vision,

Chris must ready the airlock

before crewmate Karen Nyberg can repressurize it.

As they speed through the normally 15-minute long airlock procedure,

ground control attempts to check in with Luca.

But there's still no response.

The pair are positioned head to foot,

making it difficult for Chris to see into Luca's helmet.

Right about then, I grabbed his hand.

And we had never pre-briefed this. Never talked about it.

But I squeezed his hand.

Sorry to my wife, but there had been never

a more comforting squeeze back of a hand.

That sensation of feeling his hand squeeze back

in a nice, controlled way was like, okay, we're going to be all right.

As my crewmates from the inside were opening the hatch,

I looked up and I could see Karen,

Karen Nyberg's face, and Fyodor.

The whole crew had come into the airlock to help me

and their faces.

They were so worried.

The sense of friendship, camaraderie.

It's a form of love that we should explore more, I think.

I could feel it. I could sense it. I could see it on their faces.

And I was moved.

I was obviously relieved.

I knew that the ordeal was just about to end

when they took the helmet off.

I was all smiles, and I started cracking jokes.

They were certainly happy to see me,

and I was certainly happy to see them.

A thorough investigation reveals

that a clogged filter led to the leak in Luca's suit.

To ensure that astronauts can keep breathing

if such a thing happens again,

NASA has an absorbent pad and even

a makeshift snorkel installed into each helmet.

The way water behaves in space is just one aspect of microgravity,

which is one millionth the gravitational pull

experienced on Earth.

And it's what helps keep the space station in orbit.

It's a challenge to live and work in microgravity,

but it also allows for groundbreaking studies

to be carried out on the ISS.

Biomedical experiments in space reveal that in microgravity,

protein crystals form more uniformly with fewer defects.

They tend to be higher quality. They tend to be purer and larger.

And so this is really been a great application

for the pharmaceutical industry.

A team of Japanese researchers has taken advantage of

the ISS's Kibo laboratory to investigate

proteins associated with Duchenne muscular dystrophy.

A severe genetic disorder causing progressive muscle weakness.

That series of experiments were really successful

in finding some of the crystals associated with those proteins

that they weren't able to do on the ground

and develop drugs to target those.

Other experiments focus on the astronauts themselves

and the impact the microgravity environment has on their bodies.

A vital area of research

if humanity is to venture farther out into space.

And we give periodic samples of blood and urine and saliva,

and in some cases, number two,

to test all of the different outcomes on the body.

We are both the conductors and the test subjects.

We don't like the term guinea pigs because we're not.

But we are subjects of the same, of the same kind of experiments.

In the end, we are interested in what can we glean

from performing science on the human body

in space that we cannot on the ground?

Every part of the space station is crucial

to conduct this science and maintain the lives of its inhabitants.

All the things we might take for granted here on Earth -

air, water, food - have to be designed,

calculated and engineered to work properly in microgravity.

Even using the toilet.

Close the lid.

You got to be able to use all of your facilities,

whether it's the bathroom

or the air conditioning or the water processor.

All of those systems are there for a reason because you need them.

Let's take a peek at the process.

With so little gravity, space toilets use airflow to pull urine

and faeces away from the body and into the proper receptacles.

And this valve is what activates the whole system.

Going number one, you feel pretty confident with that.

You're effectively just turning on a fan, opening a valve and peeing.

In good Nasa fashion, we have a checklist.

This is called procedure 2.301.

And in case things go wrong...

Going number two is a little bit more...

You really reread every little line.

There is a plastic liner in there where your deposit goes.

If you make the mess, you got to clean up the mess.

So you don't want to be that one.

You take this red tab,

you pull it off the rim and we do have a stick

and you push it down in there.

And then it's time to put a new bag on.

Ready to go.

But the toilets are vital to the International Space Station

in more ways than one.

Water is life. Water is life on Earth.

Water is life on the International Space Station.

Every drop of water, whether it's your urination,

whether it's your sweaty t-shirt from exercise,

the moisture in our breath as we exhale,

all of that moisture gets captured by

the environmental control system

and put back into the water processor.

This fundamental part of the space station's environmental control

and life support system allows the ISS to recycle 98%

of the water that a crew brings along at the start of a mission.

Every now and then as you're filling your coffee bag,

you think, wait a minute, this was yesterday's coffee.

And it's also today's coffee.

But the system works really well and you get alarms long before

it is anything but pure water.

While the systems on board are designed

to keep the crew alive, it is the responsibility of

the crew to maintain the space station itself,

a fundamentally symbiotic relationship.

Neither could survive for long periods in space without the other.

The ISS is the largest human-made structure in orbit ever built,

with a surface area of well over 100,000 sq ft,

exposed to the hostile environment of space.

One of the dangers in space that's outside

the vehicle are what we call micrometeoroids.

So those can come from a number of sources.

Bits of cosmic dust travelling at a tremendously high speed can hit

the shell of your module and put a hole in it.

Impact tests conducted on the ground reveal the destructive

force of high-velocity particles, some no larger than a grain of sand.

Incoming particles can reach speeds of up to 162,000mph,

up to 50 times faster than a speeding bullet.

The ISS has survived several direct hits

to its solar panels and to the Canadarm2.

The smaller pieces cause problems because they're going very fast.

So you multiply a very small number,

which is a mass times a very big number, which is the velocity.

That's where you get the problem.

The result is that even the tiniest particles can pack a huge punch.

To defend the space station,

more than 100 shields protect the critical components.

A common kind is a stuffed Whipple shield.

A multi-layered system of metal and synthetic materials

which can break up smaller meteoroids, dispersing their energy.

Russian modules tend to have thicker ribs and thinner skin,

so from a probabilistic perspective,

the Russian modules are much more susceptible

to small micrometeoroid penetrations.

On the flip side, the US modules have very,

very thick skin, so smaller micrometeoroids

are not likely to penetrate the US module.

But micrometeoroids aren't the only threat.

Increasingly, it's orbital debris

that comes from something human made.

So a screw, a paint fleck, a rocket body.

I mean, it could be anything, right?

There are so many more objects in space.

There may be bits of derelict satellites that approach your orbit.

With low Earth orbit becoming more crowded by the day,

the probability of catastrophic collision increases.

The good thing about low Earth orbit is we've seen this huge boom

of private companies and commercialisation,

and it's everywhere.

The bad thing is there's lots of old pieces of stuff out there,

whether it's spent launch vehicles, whether it's dead satellites.

Protecting the ISS now poses a unique challenge.

Today, more than 15,000 pieces of space debris

are tracked in low Earth orbit where the ISS resides.

Including fragments of used rockets and decommissioned satellites that,

with no way to regulate their temperature,

repeatedly expand and contract

until they break up or sometimes even explode.

And these are just the objects we are able to track,

those larger than four inches.

Add in smaller fragments,

and the total number of debris particles is estimated to be

in the millions.

Each fragment can go on to hit more objects,

creating exponentially more fragments and more collisions.

A potential nightmare for Mission Control.

The bigger pieces we track pretty well

and we do debris avoidance manoeuvres

sometimes because we know that there's a potential collision.

In 2021, Russia launched an anti-satellite missile,

deliberately destroying one of its own defunct satellites.

The impact created a massive cloud of high velocity debris

hurtling through low Earth orbit.

Although the initial pass missed the station,

the danger was far from over.

Subsequent orbits of the wreckage required mission control

to carry out avoidance manoeuvres to keep the ISS out of harm's way.

But rogue impactors aren't always the problem.

Every manoeuvre, every docking is painstakingly planned

and monitored by the folks at Mission Control.

And during these tightly coordinated movements

of the space station, controllers must be ready for the unexpected.

After years of delays, the uncrewed Multi-Purpose Laboratory Module,

or MLM Nauka, docks with the International Space Station.

It marks the first major expansion to

the Russian segment in over ten years.

Once docking to the Zvezda service module is complete,

at Mission Control in Houston,

Zebulon Scoville takes over flight director duties.

I did a quick handover and plugged in,

thinking that we were just going to be doing some minor

reconfigurations and stabilisations of opening hatches,

equalising the atmospheres and so forth.

It didn't quite go that way.

About 1.5 minutes after plugging in my headset,

a small yellow stripe lit up across the caution warning board

in the front of Mission Control.

My altitude control officer notifies me that we have

a loss of altitude control or low altitude.

For reasons unknown, the ISS has begun to spin out of control.

We saw on the front screens the video cameras coming from ISS,

almost a snowstorm of particles around the outside of the ISS,

and it wasn't entirely clear what the source of this was.

This could be a coolant fluid that had vented.

It could be a fuel or propellant that was leaking overboard,

or it could be thrusters firing.

The fact of the matter is we didn't know.

And so this is where we had to very quickly try to understand

what is this venting overboard?

What is it doing to ISS?

How will we first make sure this crew is going to be safe?

And second, get the vehicle under control.

French astronaut Thomas Pesquet

and his six crewmates are on board at the time.

If a space station spins too fast,

this could introduce several potential hazards.

If it were to flip upside down, now our antennas,

which are normally pointing towards our communication satellites,

are no longer pointing up,

so we risk losing communication with the space station.

We have docking mechanisms with the crew vehicles

that are used as lifeboats.

If we spin too fast, if we had to undock in an emergency,

those hooks might jam.

The advantage of building a station in the vacuum of space is

that you don't have to fight things like wind and gravity,

so the structure can be less sturdy.

The problem is,

any unexpected twisting could break it into pieces.

Ground control desperately needs to understand

what is causing the ISS to turn.

So one of my first questions was to my life support officer.

Are you maintaining cabin atmosphere?

Cabin atmosphere stable, flight.

Okay, what about cooling systems?

Thermal systems are stable, flight. We're looking good.

The team ticks off a checklist of possible causes.

Until a plausible suspect emerges.

One of the main and most likely candidates was

that the Nauka module was firing thrusters.

A software error on the Nauka means that it doesn't recognise

it has successfully connected to the ISS.

Nauka's thrusters start firing,

trying to pull away from the space station

it is now securely docked to.

Four huge gyroscopes on board the ISS keep the station in position.

As the Russian thrusters fight with the space station's gyros,

there's concern that the joints of the ageing ship

can't take the strain.

So the decision is made to shut the gyros down,

reducing the stress on the attachment points

that connect the station's modules together.

The ISS is now in free drift.

And there's an added complication.

Unfortunately, the Nauka module can only communicate with the ground

if the station was physically over the Russian ground sites.

As it was, we were just heading off of the eastern coast of Russia

over the Pacific.

And so we had no insight, no telemetry,

no data, and no ability to command it or turn it off.

We weren't going to get that back for about 90 minutes.

In Houston, flight controllers listen to real time translations of

the communications between Moscow's mission control

and the cosmonauts on board the station.

We've got 1.5 hours to ride this thing out

before we're going to be able to completely stabilise the system.

At this point, in order to assure we had every advantage we could,

I declared a spacecraft emergency.

A spacecraft emergency ensures

that all attention is focussed on the operation at hand.

All available ground antennas across the US

now attempt to make contact with the ISS.

But still, the connection between the ground and space is patchy

and unpredictable.

And with the whole ISS structure now turning away

from its communications satellites,

US operations are about to lose contact with the crew.

We were tracking the space station spin,

and we could predict we had minutes to communicate several steps

of procedure to the crew before we were going to run out of time.

The crew are instructed to lock the station's radiators,

which are at risk of shearing off,

while the solar panels are repositioned.

Meanwhile, at Mission Control...

..the team formulates a plan

to fight back against Nauka's thrusters.

We want you to run the procedure.

We knew as the Nauka module's thrusters were firing,

that we had to bring a bigger lever arm,

a more powerful force to bear against these thrusters.

For that extra muscle,

ground control turns to the Zvezda service module,

primary source for the ISS's propulsion systems.

At this time, a cargo ship, Progress 78,

is also docked to the station

on the opposite side to the misfiring Nauka.

Crucially, both Progress 78 and the Zvezda have thrusters.

Now, typically there will be days of analysis.

In this specific case, this was unexpected, and so there was a little

bit of engineering judgement that had to be applied.

Recognising that the alternative

and indecision would have been worse.

Mission control makes the decision

to fire up the Zvezda and Progress 78 thrusters to set up an orbital

wrestling match with the Nauka that they have to win.

For nearly 45 minutes, the ISS drifts out of control.

A combined effort of the Zvezda and Progress 78 modules

pushes back against Nauka.

It's putting huge strain on the space station structure.

This is like riding a bucking bronco,

and we've got to make it the full eight seconds.

Except this time it was an orbit around the entire Earth.

It will be another 45 minutes before Russian controllers

can regain command of Nauka's thrusters.

But then all of a sudden...

Nauka's thrusters fall silent.

Its fuel tanks have run dry.

The tug of war is over.

As we brought the space station back to normal altitude,

I think we all took a deep sigh of relief.

After rotating one and a half times around 540 degrees,

mission controllers can finally bring

the station to a halt

and begin a controlled return to its correct attitude.

The team that I had working in the control centre that day

was an example of performance that to this day I will always remember.

Not because we did everything perfect,

but because of how we came together.

Since its launch in 1998,

the ISS has been humanity's laboratory in the sky.

Over the past 25 years,

we have served over 5000 researchers on the International Space Station.

Conducted over 4000 different experiments.

And published right around 4000 papers.

The fact that we've learned so much, not just about technology,

but about ourselves as a result of the ISS.

That's a legacy that's not to be denied or discounted in any way.

For many, the value of the ISS goes far beyond the physical.

It's about perspective,

hope, and the shared pursuit of something greater.

The space station is not just a place where we produce science,

but it's a place of emotions.

It is a place of humanity.

A place where we brought with us our own dreams.

A quarter century of peaceful cooperation,

multiple countries, multiple organisations,

all working with the focus of trying to make humanity better.

To me, that seems like a pretty powerful and lasting legacy.

But with ageing technology and the advent of new,

more efficient space platforms, the station's days are numbered.

The ISS was never meant to be a permanent structure in space.

The International Space Station is scheduled to begin

its final chapter in 2030.

About a year and a half before the space station de-orbits,

we will launch a crew that will stay there for a year.

They will be in charge of getting the last bits of science

and engineering we can out of this facility.

About six months prior to the deorbit process,

that crew will come home,

leaving the space station uncrewed as its altitude starts to lower.

A deorbit vehicle will attach to the ISS

and gently guide the station into a slow, deliberate descent,

where it will enter the thick layers of Earth's atmosphere

at speeds over 17,000mph.

Experiencing temperatures close to 3000 degrees Fahrenheit.

We know some of it will burn up,

but large pieces of it will survive through the atmospheric re-entry.

That's why we want to make sure that it's a controlled process.

So we safely hit the Pacific Ocean.

The ISS's fiery disintegration will be the final act

in its incredible journey.

But the lessons we learned from its time in space,

the technologies developed and the unity it represents

will echo in future space exploration for generations to come.

The ISS is not just a international laboratory that's orbiting in space.

It's much, much more than that.

No matter where we come from,

no matter the differences in political systems

and the leaders that we have, we really can work together.

We have that ability.

It's just really fun to think about the future of space exploration,

and to know that I was, in a small way,

part of the International Space Station story.

The International Space Station is the crowning

achievement of human ingenuity so far.