Original subtitles

NARRATOR: In 1972, NASA starts work

on a radical new reusable spacecraft.

Its innovative design pushes engineering to the limit.

BOB CRIPPEN: They had to be light, they had to be reusable,

and they had to be very powerful.

NARRATOR: The space shuttle challenges engineers

to create a vehicle that must withstand

the explosive rigors of launch.

MATT: Just that main engine, to get that to work

is mind-boggling.

NARRATOR: Just as incredible:

the incinerating temperatures of reentry.

STORY: You’re like in the middle of a blowtorch.

NARRATOR: Not once -- but time and time again.

TOM: A lot of sleepless nights over that.

NARRATOR: Against all odds, engineers must strive

to make spaceflight routine.

BOB CRIPPEN: Flying in space is tough and it’s dangerous.

NARRATOR: This is the remarkable story of the unsung heroes

who designed, built and flew the space shuttle.

[♪ theme music ♪]

NARRATOR: April 12th, 1981. The Kennedy Space Center, Florida.

Astronauts John Young and Bob Crippen

are about to risk their lives in a vehicle

that’s never flown before.

Space Shuttle Columbia.

BOB CRIPPEN: It was a test flight.

We didn’t know exactly what it was gonna do.

MISSION CONTROL: We’ve gone for main engine start.

NARRATOR: The shuttle’s three main engines roar into life,

followed by two giant solid rocket boosters...

and the shuttle leaps from the pad.

BOB CRIPPEN: That’s when my heart rate went up

to about 130 beats per minute!

NARRATOR: As Columbia thunders skywards,

it’s the moment thousands of engineers

have dedicated their lives to --

the launch of the first-ever reusable spacecraft.

♪ ♪

The space shuttle is an engineering marvel.

For thirty years it was the workhorse

of America’s space program,

responsible for some of its most memorable achievements.

ASTRONAUT: We’ve separated about one foot per second.

NARRATOR: Launching satellites.

Delivering and servicing the Hubble Space Telescope.

And assembling humanity’s largest permanent

outpost in space -- the International Space Station.

The shuttle’s unrivaled array of space firsts

rests with an extraordinary feature

and an incredible engineering challenge:

the ability to fly in space time and time again.

♪ ♪

For years the idea of a reusable spacecraft

is the dream of early space pioneers.

ARCHIVE: The capability to launch, maneuver in orbit,

and then maneuver inside the atmosphere

so that a landing can be made at will.

ANDY: If you go back and you look at the old

science fiction films of the 50’s,

spaceships were reusable. It was accepted.

And that dream was very much alive

in the minds of the engineers at NASA.

NARRATOR: By the end of the 1960s NASA has put men on the moon.

But it’s come at a vast cost.

Each multimillion-dollar moon rocket

is discarded after launch.

DON: In the case of the rocket engines and the rocket vehicles,

they didn’t come back. They were throwaways.

They burned up in the atmosphere,

and those vehicles were expensive.

NARRATOR: With budgets for space exploration falling,

NASA must find a new solution.

One which promises to make spaceflight routine --

and ultimately cheaper.

ANDY: So you are saying to the engineers you have a chance

to build the world’s first reusable spaceship,

and it’s going to be amazing.

NARRATOR: It’s a hugely ambitious project.

And NASA must persuade the US Government to fund it.

That means recruiting a powerful ally

with a vested interest in space:

the US Department of Defense.

An eye in orbit is the perfect place

to keep watch on America’s adversaries.

ANDY: NASA understood that in order to get

the shuttle approved they had to make

the shuttle attractive to the Department of Defense.

NARRATOR: Seeing the shuttle’s potential, the DoD

agrees to join forces with NASA.

But not without two important stipulations.

First, the shuttle must be able to return

to a specific landing site after just one orbit.

ANDY: The DoD guys say launch,

take classified reconnaissance photos, and come back down

at the end of one orbit and land back at the launch site.

The problem is that while you’re doing that one orbit

in that 90 minutes the Earth is turning underneath you.

NARRATOR: Meaning the shuttle’s launch site shifts

over 1,000 miles eastward.

ANDY: That means you’ve got to launch it like a rocket

and land it like an airplane

where you can steer to the proper landing point.

NARRATOR: Such versatility is something that’s never been

attempted before with a spacecraft

but is critical in making it reusable.

Aerospace engineer Tom Moser

is tasked with the engineering challenge.

TOM: As the requirements evolved,

we knew we had to have a delta wing

like some of the fighter jets.

NARRATOR: A delta wing will give the shuttle

more controllability when returning to Earth.

At the Smithsonian Air and Space Museum,

it’s possible to see this distinctive shape

with Space Shuttle Discovery.

VALERIE: The delta wing gave this vehicle

maneuverability to move to the left, move to the right,

and it also gave it maneuverability during reentry

to make these big sweeping S turns

as it was descending to bring this vehicle home.

The wings are doing all the work.

NARRATOR: The shuttle’s delta wing design

promises the flying versatility the military requires.

But NASA must also fulfill the second major requirement

from the Department of Defense --

launching large spy satellites.

TOM: We had to carry a very large payload.

It weighed like 65,000 pounds, 15 feet in diameter

and 60 feet long.

NARRATOR: The strict military requirements

dictate the design and shape of the spacecraft,

called the orbiter.

To launch it, engineers must build three revolutionary

rocket engines fueled by a giant external tank, along with

two solid rocket boosters, giant reusable rockets,

and then combine them to provide the immense thrust

needed to lift the heavy payloads into orbit.

TOM: So it was huge. The DoD requirements were a big driver.

A huge driver in the design of the shuttle.

NARRATOR: The military’s demands create

a huge engineering challenge.

But having them on board checks the boxes on Capitol Hill.

And in January 1972 President Nixon green-lights funding

for the shuttle program.

ANDY: But this was a new idea,

and it was one thing to say it,

and it’s another thing to actually do it.

NARRATOR: Now NASA, and the engineers it will employ,

face the enormity of constructing

one of the most complex machines ever built.

♪ ♪

California, 1972.

With the space shuttle’s design determined,

engineers at Rocketdyne begin work

on a critical element of getting the orbiter into space:

its three main engines.

Fresh out of college, Dan Hausman is challenged

to help create a revolutionary rocket engine.

DAN: It was very exciting because it was

a brand new engine program,

and we called it the white truck to space.

Once a week we would take the space shuttle to orbit

and life would be good.

That’s really not how it ended up.

It was a big challenge to get that system to work.

NARRATOR: The space shuttle main engines

will be the most sophisticated ever built, and,

most importantly, reliable enough

to be used time and time again --

a demand that’s never been made of a rocket engine before.

BOB CRIPPEN: They had to be light.

They had to be reusable and they had to be very powerful.

All those factors combined to make

an extreme engineering challenge.

♪ ♪

NARRATOR: Rocket engines produce thrust by burning propellants.

Simply put, the more propellant burned each second,

the more powerful the rocket.

To increase the flow of propellant,

rockets use a spinning pump called a turbopump

to increase the fuel pressure, ultimately increasing thrust.

To lift heavy payloads, the shuttle’s engines must deliver

well over a million pounds of thrust -- a staggering amount.

MATT: Think of the engineering that is required

to make that system alone work.

Forget about everything else that’s on the vehicle.

Just that main engine, to get that to work is mind-boggling.

NARRATOR: Dan Hausman and his colleagues know

it requires a quantum leap in turbopump technology --

engineering one with a phenomenal spin rate

of up to 600 revolutions -- every second.

DAN: Your car engine runs at 3,000 rpm.

A high-pressure fuel turbopump ran at 33,000 rpm,

and the balance of that has to be perfect.

NARRATOR: But Dan’s team have an engineering solution.

Place a small rocket inside the main engine

and use its powerful exhaust to rapidly spin the turbopumps.

It’s called a preburner. It looks good on paper...

[Explosion]

... but on the test stand the engines catastrophically fail

in a fraction of a second.

BOB CRIPPEN: Those initial tests, the engines came apart quite often,

which is not a pretty thing to watch,

especially if you plan on using that to go fly.

NARRATOR: The problem is a balancing act.

If the preburner spins the pumps too slowly,

the engines won’t get enough fuel.

Too fast, and the pumps spin to destruction.

DAN: It just has to be perfect, a jewel watch;

and if it’s not it’ll just come apart,

and that’s where the issues were, was in turbopumps,

and that’s why the turbopumps have been redesigned

a number of times.

NARRATOR: Calculating something as complex as

the performance of a rocket engine is a breeze

with today’s computing power.

But with the limiting technology of the 1970s,

it’s a painfully slow process.

DAN: And all of our engineering was done on slide rules.

There was no such thing as computers.

We calculated that all by hand.

NARRATOR: Dan’s team persist,

precisely fine-tuning the turbopumps,

allowing each rocket engine to fire without a hitch.

DAN: And when those three engines actually all lit

and behaved nicely, we all said, wow, that was amazing.

NARRATOR: Getting astronauts into orbit requires

a remarkable feat of engineering.

But getting them safely back is an even greater challenge.

ANDY: Yeah, you’ve gotta have a lot of power

to get a spaceship into orbit,

but the tricky part turns out to be getting it back

through the atmosphere in that process that we call reentry.

NARRATOR: To orbit Earth requires a speed

of around 17,500 miles an hour.

But landing a shuttle safely means shedding

almost all of that energy to touch down

at around 200 miles an hour.

As astronaut Story Musgrave can testify,

this huge deceleration creates a fiery problem.

STORY: It’s just outrageous.

You think you should evaporate in a second, you are engulfed,

you’re like in the middle of a blowtorch.

NARRATOR: Early astronauts returned in capsules

with heat shields designed to survive

only one blistering reentry.

But the space shuttle must fly multiple missions,

which produces a critical engineering problem.

ANDY: How do you create a heat shield

that can withstand that searing heat and be unscathed

so that you can use it again?

NARRATOR: For the engineers this forces a radical rethink.

The Holy Grail is a material that can withstand temperatures

of up to 2,300 degrees Fahrenheit.

Eventually engineers discover a breakthrough.

ANDY: In the 1960s, Lockheed, working with the help of NASA,

came up with a new technology.

And that new technology was made out of silica,

just like beach sand.

NARRATOR: It’s discovered that silica can be used

to create a hard, lightweight ceramic

with amazing thermal properties,

providing an extremely good barrier against heat,

as thermal protection systems engineer Martin Wilson

demonstrates.

MARTIN: If you heat it up, it tends to cool off very rapidly.

So you can hit it with a lot of heat.

It gets very hot very quickly,

but it also sheds heat very, very rapidly also.

And the back is just cold to the touch.

NARRATOR: Silica ceramics fit the bill as a reusable heat shield.

But the engineers aren’t out of the woods yet.

Now they must find a way of covering

the shuttle’s aluminum airframe.

But it’s much larger and more complex

than conical reentry capsules.

Engineers plan to clad it with thousands of custom-made tiles.

BOB CRIPPEN: The tiles were essentially all different.

Every one had to be manufactured specifically

for a particular spot on the vehicle.

NARRATOR: It’s a painstaking task.

Over 33,000 tiles must be cut, fired and precisely glued.

But in March 1979,

with its maiden flight just one year away,

orbital assembler Rockwell International

are falling behind schedule.

They transport the orbiter from their plant in California

to Florida, where the remaining tiles will be attached.

♪ ♪

But the trip reveals a design flaw which requires

a radical rethink if the shuttle is to make it into space.

When Columbia arrives at the Kennedy Space Center

on the back of a specially modified 747 Jumbo Jet,

engineers like Bob Sieck can hardly believe their eyes.

BOB SIECK: It didn’t look as nice as

the advertising brochure would’ve indicated.

There was lots of exposed skin.

NARRATOR: Thousands of tiles are missing.

Many have fallen off in transit.

It’s a shocking realization.

TOM: The tiles didn’t have sufficient strength to stay on.

Means we can’t fly. Pure and simple. Could not fly.

ANDY: So suddenly the engineers had to stop and say,

oh my God, how are we gonna prevent this from happening

to a shuttle in flight?

NARRATOR: The shuttle is grounded.

NASA scrambles to understand why so many tiles have fallen off.

The answer lies with something as small as stitching.

The shuttle is designed to flex

during the stresses and strains of flight.

But attaching tiles to a flexing airframe

is a recipe for disaster.

So the tiles are glued onto stitched felt pads

that absorb the forces, keeping the tiles from cracking.

TOM: The tiles are very rigid and very fragile,

so the pad allows the tile to move relative to the aluminum.

NARRATOR: But on inspection a startling discovery is made.

The orientation of stitching within the felt pads means

that instead of absorbing the forces of flexing,

the pads are amplifying them.

It’s why so many tiles were lost in transit.

For the engineers, the fix is a daunting realization.

TOM: So we had to make the tiles stronger.

That kept us awake at night.

A lot of sleepless nights over that.

NARRATOR: Engineers experiment with how to strengthen

the tiles so they’ll remain attached to the felt pads.

Their breakthrough is painting the bottom

with a mix of silica, water and ammonia and then baking them.

The solution soaks into the tiles, adding extra silica,

which sets hard when heated.

It’s a process called densification.

TOM: It doubled the strength of the tile

and essentially did not increase the weight a bit.

Did not change the thermal performance. It was a miracle.

Well, it was not a miracle, but it was good engineering.

NARRATOR: It might be good engineering,

but the implications are massive.

Thousands of tiles must be stripped from Columbia

and strengthened.

TOM: We had to take them off the vehicle, densify them

and put them back on the vehicle.

NARRATOR: Desperate to have the shuttle ready for launch,

NASA must expand its tile workforce from 200 to 3,000.

ANDY: Now you have to call in an army of technicians.

This is like a mobilization in wartime.

It’s gotta happen for just this one problem.

TOM: It was a schedule nightmare.

And we literally counted tiles. How many we’d put on?

How many did we take off? How many do we have left to go?

NARRATOR: More than a year is spent working round the clock

to complete Columbia’s thermal protection system.

♪ ♪

The astronauts know their lives depend

on the quality of this work.

BOB CRIPPEN: John Young and I spent a lot of time

with the people that were doing the tile work

telling them how much we appreciated the effort

they were going through, how important it was.

It was your body that was going to be strapped into that thing,

and you wanted to make sure it would work.

NARRATOR: Fixing Columbia’s heat shield ranks as

one of the crowning engineering achievements

responsible for certifying the space shuttle ready to fly.

♪ ♪

April 12th, 1981.

Columbia finally stands poised for its first test flight.

Preparing to board are Commander John Young

and Pilot Bob Crippen.

BOB CRIPPEN: Flying in space is tough and it’s dangerous.

It was a test flight.

We didn’t know exactly what it was gonna do.

NARRATOR: Chief shuttle engineer Bob Sieck is in the firing room.

BOB SIECK: There was tension, apprehension;

but on the other hand there was confidence saying,

hey, we’ve done the best we can.

TOM: The anxiety was high, extremely high,

because we had two of our, two of our colleagues on board.

MISSION CONTROL: T minus 10, 9...

NARRATOR: The astronauts ready themselves

for the flight of a lifetime.

BOB CRIPPEN: I turned to John and I said,

"I think we might do it."

NARRATOR: At T minus 6 seconds, the shuttle’s fuel pumps

spin into life as the engines ignite.

MISSION CONTROL: We’ve gone for main engines start.

♪ ♪

BOB CRIPPEN: And that’s when my heart rate went up

to about 130 beats per minute. I was pretty excited.

TOM: It was like something being born saying,

"Look, I’m ready to go!"

NARRATOR: Finally, as the shuttle’s two

solid rocket boosters ignite, Columbia surges from the pad.

♪ ♪

BOB CRIPPEN: I mean you get up and move, you clear the tower

in a couple of seconds!

[Engines roaring]

♪ ♪

NARRATOR: The engineers in the firing room

can hardly contain their excitement.

BOB SIECK: There’s this initial shout of joy from the control room,

big roar, and then we all remembered our discipline

and it was immediately quiet.

NARRATOR: After a bone-jarring two minutes,

the mighty solid rocket boosters are spent.

MISSION CONTROL: This is the SRV-7 flight...

BOB SIECK: Another big roar, and then another,

"Oops, remember our discipline." Quiet.

MISSION CONTROL: Negative [inaudible]. Columbia, you’re negative [inaudible].

BOB CRIPPEN: At that point it gets really quiet.

You’re not shaking anymore.

It’s about as calm as me sitting here in this chair.

NARRATOR: Finally, eight and a half minutes after launch,

Columbia’s three main engines shut down,

having performed perfectly.

[Laughing]

BOB SIECK: Euphoria reined. High five, hugs, handshakes,

tears, flag-waving.

LEE: There probably wasn’t a dry eye in Firing Room 2.

I mean, it was just an emotional experience.

NARRATOR: After almost a decade of engineering toil,

Space Shuttle Columbia arrives in orbit.

Engineers and astronauts are ecstatic. But it’s short lived.

♪ ♪

As the astronauts open the shuttle’s payload bay doors,

they’re greeted by an alarming sight.

Missing protective tiles -- which could spell disaster

for their safe return to Earth.

BOB CRIPPEN: When I opened up the payload bay doors,

I saw that we had some tiles missing.

It did cause a lot of consternation on the ground.

ASTRONAUT: We do have a few tiles missing.

MISSION CONTROL: Roger Cripp, we can see that good.

NARRATOR: Unmistakable black patches reveal where

tiles from the spacecraft’s heat shield have torn off.

Luckily, they’re missing from a noncritical area

on the topside of the vehicle.

ANDY: Now, that part of the shuttle is not a real cause

for concern because it does not experience

the really intense heating during reentry.

But what no one knows is, are we also missing tiles

underneath the shuttle,

where a missing tile could be catastrophic?

NARRATOR: During reentry, Columbia’s underside

will experience searing temperatures

of up to 2,300 degrees Fahrenheit.

Tiles lost from here pose a significant threat

to the astronauts’ survival.

TOM: If a tile was missing, there was no way to repair it.

There was nothing to do.

NARRATOR: The fate of Columbia’s astronauts

will only become clear when they reenter the atmosphere.

♪ ♪

April 14th, 1981.

After a near-textbook two days in orbit,

Columbia begins the final critical part

of its maiden flight,

slamming into the atmosphere at over 17,000 miles an hour

as it returns to Earth.

BOB CRIPPEN: It’s about Mach 25 when you hit

the Earth’s atmosphere at around 400,000 feet.

NARRATOR: As Columbia begins to experience the blazing heat

of reentry, all thoughts are on the orbiter’s

thermal protection system.

TOM: That was a scary moment.

ANDY: You know, who knew if this thing

was actually surviving reentry?

TOM: We didn’t know if it would burn through or what.

NARRATOR: Enveloped in a searing shroud of plasma,

radio communications with Columbia are lost

for a nail-biting 16 minutes.

ASTRONAUT: Houston, Columbia’s here.

MISSION CONTROL: Columbia, Houston’s here. How do you read?

NARRATOR: But right on schedule, communications are restored.

And the relief in Mission Control is palpable.

ANDY: It was only when that call came through

that everybody could breathe a sigh of relief.

NARRATOR: Columbia’s heat shield survives reentry,

and, escorted by two chase planes, the orbiter glides

toward a landing at Edwards Air Force Base

in California’s Mohave Desert.

BOB CRIPPEN: No rattling or shaking. Just as smooth as can be.

Bit like you coming in a commercial airliner somewhere.

♪ ♪

TOM: It was an "ahh" moment.

BOB CRIPPEN: Wow, this thing works. It’s great. It’s a super machine.

[Cheers and applause]

NARRATOR: For the first time in history, a spacecraft

has been launched as a rocket and returned as a glider --

a reusable vehicle ready to fly in space again.

♪ ♪

The success of Columbia paves the way

for a new era in space flight.

NASA rolls out three more orbiters,

Challenger, Discovery and Atlantis,

deftly demonstrating the shuttle’s ability

to carry a wealth of scientific experiments, satellites

and commercial payloads into orbit.

♪ ♪

For a while it seems spaceflight has become almost routine.

MISSION CONTROL: T minus 4 minutes and counting.

NARRATOR: January 28th, 1986.

MISSION CONTROL: We have main engines start, 4, 3, 2, 1 and liftoff.

Liftoff of the 25th space shuttle mission,

and it has cleared the tower.

ASTRONAUT: Roger that, Challenger.

MISSION CONTROL: God, no!

MISSION CONTROL: Fight controllers here looking very carefully at the situation,

obviously a major malfunction.

LEE: Immediately we know there’s been a tragedy.

We know that seven lives have been lost.

NARRATOR: Just 73 seconds after launch,

Space Shuttle Challenger disintegrates

in a devastating fireball.

LEE: You can’t help but think, what happened? What did we do?

What did we not do? What step did we miss in a procedure?

NARRATOR: Immediately after the disaster,

many engineers suspect the failure lies

with one of the shuttle’s most complex components --

its main engines.

But engineer Dan Hausman knows it’s too early

to jump to conclusions.

DAN: We were told it was an engine failure.

Then I said, it could have been.

Until we look at the data, we don’t know.

NARRATOR: Hausman and his colleagues meticulously pore

over every millisecond of data returned from each engine.

DAN: Those engines, they were working

just like they were supposed to.

NARRATOR: Leading them to a more surprising conclusion.

DAN: I quickly realized that it was an SRB issue.

NARRATOR: The two solid rocket boosters -- SRBs for short --

help lift the shuttle off the pad.

Firing for just over two minutes,

they’re the largest of their type ever built.

They draw on tried and tested technology, and,

compared to the main engines,

their design is relatively simple.

STEVE: I never considered that the booster

would ever cause us a problem.

Because the booster really had no moving parts.

NARRATOR: But analyzing film footage of Challenger’s launch

suggests otherwise.

STEVE: The first indication that we had

was a film of the launch.

You see a puff of smoke when they ignite the boosters.

NARRATOR: The footage provides investigators with a vital clue.

BOB CRIPPEN: Hardware talks to you.

STEVE: It was trying to tell us we had a bad joint design.

From the very beginning.

NARRATOR: The solid rocket boosters are stacked

from a number of segments joined together.

Inside each joint are flexible rubber bands called O-rings.

On ignition, pressure inside pushes on

the flexible rubber O-rings, forcing them to seal each joint.

But the black smoke caught on camera

suggests an O-ring seal has failed.

Engineers need to understand why

a catastrophic failure occurs during this launch

compared to the previous 24 successful launches.

The team redoubles their efforts.

BOB SIECK: On the morning that we actually launched Challenger,

it was cold.

STEVE: If you go look, it was, there was ice on the pad.

NARRATOR: The night before launch, temperatures plummet

into the low 20s -- almost unheard of in Florida.

Investigations discover that at these freezing temperatures,

the rubber-like O-rings become brittle and

fail to seal the solid rocket booster joints as designed.

This leads to the devastating chain of events with Challenger.

STEVE: So what you actually have is something

that looks like a blowtorch.

You’ve got 6,000-degree gas going over both O-rings

and out into the environment.

NARRATOR: A little over a minute after launch,

searing exhaust from the breached O-ring

burns through the SRB’s lower strut,

causing it to pivot into the giant external fuel tank,

which ruptures, cascading tens of thousands of gallons

of fuel into white-hot exhaust.

BOB CRIPPEN: It was certainly not a day we should’ve gone flying.

NARRATOR: The loss of Challenger is a huge blow for NASA

and the engineers.

DAN: After Challenger there’s a lot of us wanted to quit.

We didn’t want to be part of a program

that cost people their lives.

We didn’t want to be a party to that.

And so they brought people in to talk to us and said,

"You know, we need you guys to help work

so that doesn’t happen again."

And so some people quit. They just couldn’t handle that.

And so the rest of us just worked very hard

to make sure it wouldn’t happen again.

NARRATOR: Engineers redesign the SRB joints and O-rings,

adding triple redundancy, with heaters that will keep them

at a constant temperature.

BOB CRIPPEN: Some people felt that was a belt and suspenders,

but it made me feel a lot better to go fly.

♪ ♪

NARRATOR: September 29th, 1988.

After a comprehensive engineering review

and with hundreds of safety modifications,

Space Shuttle Discovery heralds a return to flight

of America’s manned space program.

♪ ♪

The next 15 years sees the shuttle once again prove itself

as an engineering marvel.

But its sheer complexity means the odds are stacked against it.

February 1st, 2003.

After 16 days in orbit, Columbia and its crew

are on their way home,

blazing through the atmosphere at 25 times the speed of sound.

Then, just 15 minutes from landing,

Mission Control are unable to establish radio contact.

Unknown to them, Space Shuttle Columbia has disintegrated

in the skies above Texas.

MISSION CONTROL: Columbia, Houston, UHF comm check.

NARRATOR: Eventually NASA’s worst fears are realized --

the loss of the orbiter and another seven astronauts.

For NASA, losing a second shuttle is devastating.

But the most likely cause makes it even more unbelievable.

MISSION CONTROL: Okay, everybody.

No data, no phone calls, no transmission anywhere outside.

NARRATOR: Film footage reviewed after launch

reveals a piece of foam insulation falling

from the external fuel tank.

It strikes the leading edge of Columbia’s wing.

VALERIE: This is the leading edge of the delta wing.

It’s made of a reinforced carbon-carbon,

and it’s actually a cap that fits over the edge of the wing.

It takes the highest heat of all during reentry.

NARRATOR: And it’s during reentry that Columbia is lost --

suggesting its protective heat shield

of reinforced carbon-carbon or RCC may have been breached.

MATT: We really didn’t think something that was

as light as a feather could break something as tough as RCC

in half.

NARRATOR: But as engineers begin their investigations,

the truth behind Columbia’s disintegration

will become tragically clear.

♪ ♪

Space Shuttle Columbia’s destruction

leaves engineers dumbfounded.

How could a seemingly harmless piece of foam

smash a hole in the orbiter’s critical heat shield?

Ballistics expert Matt Melis is one of the engineers

tasked with finding out.

MATT: We got a phone call from one of the folks

at Johnson Space Center, and they said,

"We think that this is an impact problem,

and we think we’re going to need your help."

NARRATOR: What they find is disturbing.

MATT: So this is a little piece of foam, it weighs two grams.

This is an example of the test specimens that we shot.

It weighs what a sheet of paper weighs.

The reinforced carbon-carbon -- and this is test sample of that

-- this is what the leading edge of the wings are made out of.

And our tests showed that, if going fast enough,

500 miles an hour, which is not that fast in aerospace terms,

this little piece of foam can cause critical damage

to this material, which is as tough as nails.

So it’s an amazing lesson that we learned from that.

NARRATOR: The team examines the launch footage

to determine exactly where the foam struck.

They narrow it down to a specific area --

between carbon panels 6 and 9 of Columbia’s left wing.

Building a replica,

they focus on this part of the leading edge.

Using a powerful airgun, they first fire foam at Panel 6.

It remains intact -- leaving the engineers puzzled --

but a vital clue helps their next test.

In the search for debris, investigators find

fragments of Columbia’s leading edge panels

belonging to the wing that was struck.

MATT: They began to piece these tiles together

and these fragments of the leading edge together,

and they showed molten material in the area of Panel 8.

NARRATOR: Most metals melt at extremely high temperatures,

the kind experienced during reentry.

Discovering so much melted metal around Panel 8

is the breakthrough the engineers need.

MATT: That really provided supporting evidence

that this foam strike took place in the region of Panel 8.

NARRATOR: The final piece of evidence comes from

the foam firing tests.

Engineers now focus on Panel 8.

And the results are shocking.

TEST FACILITY: 5, 4, 3, 2, 1, 0. Whoa!

MATT: A piece of foam ultimately caused the loss of the vehicle

and the loss of seven lives.

NARRATOR: Engineers learn from the tragic lessons.

But with the loss of two orbiters and 14 astronauts,

the shuttle program’s days are numbered.

ANDY: The Columbia accident,

like the Challenger accident before it,

was a very painful reminder that there was nothing routine

about flying the space shuttle.

NARRATOR: July 8th, 2011.

♪ ♪

Space Shuttle Atlantis lifts off on the program’s final flight.

Over three decades, 135 shuttle missions chalk up

a combined three and a half years in orbit, carrying

355 individual astronauts from 16 different countries.

and delivering over three and a half million pounds of payload.

But ultimately the shuttle’s complexity means

the running costs -- and risks --

are too high to continue flying.

Today the shuttles reside

in the Smithsonian’s National Air and Space Museum

and other exhibits around America,

an inspiration to all who come to see them.

BOB CRIPPEN: You can’t fly a vehicle like this

and not appreciate the handiwork of everyone

that was involved in it.

MATT: The accolades that those people deserve,

it’s just an absolutely incredible amazing feat.

VALERIE: They did what it took to keep this

remarkable flying machine in service as the icon

of American’s aspirations in space.

NARRATOR: The shuttle’s work is now complete.

But its engineering legacy will outlast those who built it.

Of all things with wings, the shuttle has to be

the most magnificent flying machine of all.