Original subtitles

Today, on Impossible Engineering, China's biggest construction.

One breaks the sky. Look at this super power.

The other extends beyond them. It can pick up radio waves from billions of

years away.

Relying on pioneering innovations of the past.

Believe it or not, these are sound mirrors.

It took revolutionary engineering to make the impossible possible.

Since the dawn of time, humanity has sought to unravel the mysteries of the

universe. And in Guizhou province in southwest China is a massive instrument

that will further this quest.

Tucked into a natural basin sits one of the world's newest and most advanced

space exploration devices.

The 500 -meter Aperture Spherical Radio Telescope, or FAST for short, is the

largest and most sensitive single -dish radio telescope in the world.

It can pick up radio waves from billions of light -years away.

This massive 1 ,600 -foot diameter antenna consists of a spider's web of 10

steel cables, weighing nearly 1 ,800 tons.

These support a sprawling 4 ,450 triangular panels, which form the dish

And at the center, suspended from six 330 -foot high towers, hangs a 33 -ton

receiver cabin.

This incredible device collects data from billions of light years away.

This is the most amazing telescope in the world.

When we propose such a big telescope,

nobody believes this big dish can be built.

The first problem engineers had when constructing this thing is its sheer

Fast is vast.

So how can fast engineers build a receiving dish of such epic proportions?

This would be impossible without history's greatest innovators.

During America's post -war housing shortage, architect Richard Buckminster

Fuller bucked the traditional house.

He developed the geodesic dome house.

The Eden Project in Cornwall, England, uses the geodesic concept on a massive

scale to house plants from different climates, including the tropics.

Measuring 55 metres high, 100 metres wide and 200 metres long, surrounding an

area the size of 34 football pitches, the rainforest biome is actually large

enough to house the Tower of London.

So how can a geodesic dome cover such a vast amount of space?

The real strength of Bolo's design was that it was made with a series of

triangles. Now the triangle, with its fixed angles, is actually the strongest

two -dimensional shape. Now I want to show you exactly how this works by

building one of these using only these.

As I'm joining the triangles together, they begin to form the shell of my

structure, and the rigidity of each triangle begins to form a tremendous

strength.

It's only when the final piece gets added that the strength comes together.

The bigger the dome gets, the stronger it becomes.

The only human -made structure to do such a thing.

It's very strong.

So we see, Fuller's design definitely works, just like the biomes behind me.

Oh, amazing.

Even more incredibly, when a sphere's diameter is doubled, its surface area

quadruples, creating eight times the volume with very little surface area.

This results in less materials and less expensive homes.

FAST's engineers are supersizing Fuller's geodesic dome concept and

on its head.

Workers construct a one -mile -long steel girder ring, forming the outer

perimeter of the dish.

Six 300 -foot -high towers surround it and support a 33 -ton feed cabin.

This houses the all -important receiver, designed to capture even the faintest

of galactic radio waves.

So, in order to build such a giant spherical reflector, a GeoDC

triangular design is the best choice.

After just five years of construction, on July 3rd, 2016, the engineers lowered

the last aluminum triangular panel into place.

is massive and that's ideal for collecting those weak radio signals from

billions of light years across the universe.

But it also presents engineers with a big problem.

Fast is so huge it has to be fixed to the ground.

Smaller radio telescopes have a receiver fixed at the center of the dish to

collect reflected radio waves.

The dish rotates to point at the exact area under observation.

But the FAST dish is too enormous to do that.

As you can see from this rather nifty little scale model, you can't just tilt

the whole landscape to point fast at a particular galaxy you might be

in studying.

So how do you make a telescope the size of FAST point at different places in the

sky?

To resolve this, the team must draw on history's greatest innovations.

They find inspiration in these monolithic structures, which once

shorelines of Great Britain.

Believe it or not, these are sound mirrors.

During the First World War, pioneering acoustic physicist William Sansom Tucker

designed these sound mirrors not to see, but to hear approaching enemy aircraft.

Here at Denj is some of the finest examples of Tucker's work, and they're

slightly different size and have different structures.

They're all based on a curved surface known as a paraboloid.

Sound waves hit a parabolic reflector at different places. When those reflected

rays meet at the focal point, the sound amplifies.

I'm going to attempt to recreate an early warning scenario.

So I'm going to place this microphone at the focal point.

So about there.

And all the sound waves are going to bounce off that reflector and be

by that microphone.

And that's represented by the blue curve here. And the red trace is a control

microphone that's placed off to one side. The curves are the same.

I can't really see any difference.

But as aircraft approach from many miles away, the parabolic sound mirrors let

sound technicians hear the engines in time to alert air defenses.

So I can start to hear something.

I can definitely hear a plane propeller.

So I can definitely see that the blue curve is above the red one in this

region here.

And historically, we could use these sound mirrors to detect airplanes about

or 20 miles away.

To detect radio waves from different areas in the sky without moving the

telescope, FAST engineers are revolutionizing the concept of multiple

sound mirrors.

with a single but dynamic 1 ,600 -foot diameter dish.

From down here, you can really see what's unique about FAST.

It uses these actuators to distort the dish.

They use 2 ,000 of these actuators to pull that dish down into that perfect

parabolic shape to get the sharpest possible images of the sky.

This system of actuators lets astronomers point each individual panel

area of the sky they wish, transforming this big, apparently static dish into a

dynamic moving reflector.

That is the sound of this actuator starting up, and believe it or not, it

actually is moving very, very slowly, about a millimeter every second.

So rather than just looking straight up, FAST can actually scan a region 40

degrees either side of that so -called zenith.

This really is an incredibly innovative solution they come up with here at FAST.

But distorting the dish into a paraboloid is just the first step toward

unveiling the mysteries of the universe.

To make the most powerful radio telescope on Earth, engineers must look

past. Oh, my God.

I just took off an airplane.

To create more impossible engineering.

In China, engineers have created the country's biggest radio telescope.

And it's the most powerful terrestrial tool in space exploration, the FAST

telescope.

Engineers can alter FAST's enormous parabolic dish surface to collect radio

waves from different areas of the sky.

But as the reflectors change angles, the central focal point also changes.

This is the sensor cabin, and it's right at the heart of FAST.

Now, in order to track a galaxy moving across the sky, you're going to have to

keep moving this to keep it in exactly the right spot to look at the object

you're interested in.

So, how do you move a 33 -ton receiver cabin dangling around 300 feet high and

still capture radio waves with pinpoint accuracy?

To accomplish the impossible, fast engineers must look to the past.

They turned to an innovation from 1964 when American engineer Klaus Kappel was

developing a realistic flight simulator.

And here they are.

These cutting -edge machines are some of the most advanced flight sims available

today.

You can see here there are six hydraulic jacks or actuators. They're positioned

in pairs and move independently from each other.

Using these hydraulic jacks, Capel created what's called a motion platform,

forerunner to modern flight simulators.

Oh, my God.

I just took off an airplane.

I can't see. What do you do?

Just like a real plane, these jacks allow the motion platform to move the

in what's known as six degrees of freedom.

With

its

dynamic range of movements... and its pinpoint accuracy, these motion

have opened up a world of possibility across a diverse range of applications.

The engineering team at FAST is raising this innovative motion platform

technology to astronomical height.

to search the sky with unbelievable precision.

Engineers created this.

A lightweight cabin that can be moved anywhere across the surface of the dish.

real innovation.

In here, we've got receivers sucking all that data and sending it back to the

control room.

But in order to keep those in exactly the right spot, we've got two different

mechanisms at play.

First, we've got those six towers out there, which tug the cabin to

approximately the right position using the servo mechanisms and those six huge

steel cables.

Computers control each cable and position the cabin as high as 450 feet

anywhere along a 675 -foot trajectory.

And like Capel's flight simulator, the cabin pivots by using a motion platform.

For that final bit of precision, we've got those six hydraulic pistons

controlling this platform, which allows the position to be located to within one

centimeter in this 500 -meter dish.

But truly precise astronomy also depends on the location itself.

Human beings make a lot of electronic noise, such as cell phone, microwave.

All the electronic devices make magnetic waves.

So all these devices generate interference to our telescope.

To avoid any such radio interference, engineers scope out a quiet, remote

of southwest China in the Guizhou province, 105 miles from its capital,

But even out here, gathering highly sensitive astronomical observations,

have been impossible without one major breakthrough from the past.

At Green Bank Observatory in West Virginia is an iconic device that

one engineer's accidental discovery unveiled a hidden universe.

For most of the history of astronomy, everything that we learned about the

distant cosmos came from studying optical light, the kind of light that we

with our eyes.

But in the 1930s, the dedication of one man changed all of that.

Bell Telephone Laboratories engineer Carl Jansky was trying to eliminate

interference in shortwave radio communications across the Atlantic.

To trace this interference, Jansky built a large antenna.

The antenna was mounted on a platform sitting on tires that allowed it to

rotate, taking a full 360 -degree scan of the sky once every 20 minutes.

His initial findings revealed a faint but persistent hiss that would rise and

fall throughout the course of the day.

The signal was strongest in the direction of the center of our galaxy.

Jansky concluded that what he was actually picking up... It was radiation

the Milky Way galaxy itself.

Jansky's extraordinary breakthrough revealed a new corridor to the cosmos.

Radio telescopes soon yielded groundbreaking discoveries.

And in 1964, astronomers used them to actually record the faint echoes

from the distant origin of the universe, the Big Bang.

Jansky's work offered definitive proof that radio waves could be detected

from the cosmos.

Engineers at FAST are taking this revolutionary radio technology even

and are attempting to detect radio waves emitted by advanced extraterrestrial

life.

But how do you assemble all the signals from space?

and transform them into usable data?

I'm going to take that phenomenal amount of data and turn it into a picture.

To do this, the team must make the impossible possible.

In China, the fastest... Telescope is the largest and most powerful single

radio telescope on the planet.

And this is where the action happens.

This horn is part of a beam receiver.

It slurps up those radio waves and detects how strong they are.

But this poses a huge challenge for the engineers and scientists here at FAST.

You've got to take that phenomenal amount of data and turn it into a

So how do astronomers and engineers transform radio waves into images?

Through the dramatic advances in computer processing, the FAST team can

transform faint radio wave signals into otherworldly images.

The modern radio telescope always tries to visualize the radio signals you

detect from the telescope.

With a computer, you can display these signals with different light curves.

Astronomers use computer software to label each individual wave with a color

code. The buildup of color forms a recognizable visual pattern.

But to create such radio images, astronomers must process a lot of data.

We expect a fast can generate 40 terabytes per night, so we need a

huge amount of storage system.

So here we have a lovely 1 .6 petabyte storage, and also we have a high

-performance computing system to process the data.

This is very exciting for each other, also I think for the human being,

they all know some new knowledge about the unknown, about the universe.

Officially completed in September 2016, FAST is now searching the skies further

and deeper than ever before.

Also scraping the Chinese sky... Look at this superpower.

...is China's tallest building and the most technologically advanced skyscraper

on Earth.

I still feel like it's a dream.

Still unbelievable.

Shanghai is a megacity with 24 million inhabitants and rising.

The only place left to build is up.

Over 2 ,000 feet high, the Shanghai Tower is the tallest building in China

the tallest skyscraper ever built in a seismic zone.

Building a super high -rise building in Shanghai is quite unique because you

have to deal with the wind low and also the earthquake low.

It's the most technologically advanced skyscraper on the planet.

With 128 floors and nine indoor gardens, where 16 ,000 people work,

sleep, and play.

Structural engineer Dennis Poon has to take on many challenges, but must first

start at the building's foundations.

That's because the land under this massive metropolis is sinking.

Its shallow water table is collapsing under the tremendous weight of the

modern buildings.

With its weight of 850 ,000 tons, how do you support it? In the soft soil

condition, which is locally in Shanghai.

The engineers only have one shot, with a skyscraper over 2 ,000 feet tall.

For a supertower, of course, the whole design challenge is to do the foundation

right, so you don't have future problems, because you can't fix it

To bolster these foundations, engineers must look to the great innovators of the

past.

Chicago is home to some of the world's most iconic skyscrapers.

But just over a century ago, building anything taller than just a few stories

was thought to be impossible.

We've got soil here that is incredibly squishy.

This is a really difficult thing to build a skyscraper on, of course,

when you load the building, the building's going to sink.

As Chicago began to boom, the demand to grow higher and maximize space posed a

problem for city planners.

In 1889, the 236 -foot -tall auditorium building at Roosevelt University was the

tallest in the city. To overcome its weak foundation, Engineer Dankmar Adler

something extraordinary.

We're headed down to see Adler's specially designed foundations to deal

soil here in Chicago.

Adler's idea was to use wood and steel crossbeams encased in concrete to create

a reinforced concrete raft for the 110 ,000 -ton building to sit on.

The method that we're standing on here, it's sort of the equivalent of...

kind of penny that I'm going to illustrate.

So this pad or this raft is put down, and then the building, the column on top

of that is put on top of that. And you can see that I can push it down a little

bit into the clay, but not really that far.

This is distributing the load.

Adler's revolutionary solution showed how soft, substandard soil could support

heavy buildings.

To make the impossible possible, engineers in China are taking Adler's

raft design and supersizing it. If the building does not settle uniformly, it

will tilt.

Because the building is so tall, a slight tilting will cause a big

the top.

In 2008, the two -year operation to build the Shanghai Towers Foundation

First, workers sink hundreds of deep supporting piles into the soil.

For 60 hours, and with 450 concrete trucks, 2 ,000 workers pour continuously

create the concrete raft.

You can see the sheer scale of this tower, and you can imagine how big the

foundation we need to support this tower in a soft soil condition.

And we get it done right.

Look, I even cannot believe it.

But the foundation of the Shanghai Tower is just the beginning.

For a super tall building, you have enormous forces to support.

We're not building a house, we're building a 128 -story building.

To design China's tallest skyscraper with the strength to support over 800

tons, engineers look to breakthroughs of the pact to make the impossible

possible.

The Shanghai Tower, China's tallest skyscraper.

To design an epic building weighing over 800 ,000 tons, engineers must look to

the past.

They find inspiration, strangely enough, in this crumbling mill in England.

This incredible but rather sad and dilapidated building in Shrewsbury is

arguably the world's first skyscraper, the first time that iron was used in a

multi -story frame construction.

Built in 1796, Ditherington Flax Mill was the brainchild of engineer Charles

Beige.

Instead of relying on the wall, the weight of the building is held together

its iron frames, making the sky the limit for the first time.

This main building had five floors, including this attic, which was

unheard of. It had a working area of over 2 ,800 square meters or 31 ,000

feet. And these narrow, relatively lightweight metal beams would be able to

support much more weight than the solid brick walls of previous buildings.

What Beige achieved in this building was truly remarkable.

In China, the engineers are taking Beige's revolutionary multi -story frame

higher. Not with iron, but with steel.

Because the external walls don't need to be load -bearing, they don't even need

to be straight.

And they can be made with glass.

The building looks different shape.

The movement looks different.

You feel like it's alive, something alive organism.

You know, because I don't feel like it's a dead, just a cold object.

With the internal steel frames holding it, the glass forms a giant curtain.

This distinctive architectural feature gives the building its sense of breadth.

Here we are. We are standing on the 8th floor of the building.

You don't want to block too much sunlight to a massive structure. It

every feeling.

But elegant design aside... How do you build a giant skyscraper that can safely

transport 16 ,000 people daily?

Who wants to come up to a 100 -story building and work up there?

This engineering feat would have been impossible just a few centuries ago.

In 1852, Elisha Otis pioneered a simple mechanism that changed the elevator

forever.

So we're here in Bristol, Connecticut at the Otis Elevator Company test

facility. So I think it's important to remember that Otis didn't invent the

elevator. But what Otis did do was to recognize that people were afraid of

into an elevator. So at the 1853 -1854 World's Fair, he built this device to

provide a break, a safety in case the rope broke.

At the World Fair, he stepped onto the platform, rose above the crowd, and gave

the signal for the rope of his elevator to be cut.

So let's see if Mr. Otis' invention still works.

Ready whenever you are, Rich.

Otis' system features a wagon spring.

It's held up by a rope, keeping the spring in a state of constant tension.

When the rope is cut, the tension in the spring releases.

causing pins fixed to the side of the spring to lock into a ratchet located in

the wood frame.

This brings the falling elevator to a complete stop.

And all these years later, every single elevator today around the world has a

similar safety device that is allowing passengers to feel safe in tall

buildings. And I didn't flunge to my death.

Otis's first passenger elevator traveled 8 inches a second. At that speed, it

would take nearly an hour to reach the top of the Shanghai Tower.

For this tower, we are using the world fastest elevator traveling at 18 meters

per second, which is faster than the speed of a car traveling at normal

speed.

The Shanghai Tower boasts 106 elevators. including one that travels a world

record -breaking 1 ,898 feet.

But at 128 stories, the Shanghai Tower must brace against powerful

winds. Even worse, Shanghai is in a typhoon zone.

which is almost 4 kPa.

So it's a huge wind pressure.

How do we resist this wind pressure?

For China's tallest skyscraper to overcome this force of nature, engineers

brace it for the storm.

We start to get this low pressure, low pressure, low pressure, low pressure,

that causes this oscillation back and forth.

And make the impossible possible.

At over 2 ,000 feet high, the Shanghai Tower is the tallest in China.

But to brace this skyscraper for typhoon -level winds, engineers must rely on a

far -reaching innovation from the past.

In 1959, engineer Jack Cermak pioneered the first wind tunnel designed for

buildings.

At wind engineering firm RWDI, engineers test multiple architectural shapes

against a variety of wind currents.

A scale model of New York's former World Trade Center is being placed into a

model of the London skyline to see what effect wind can have on tall buildings.

So the wind is coming in here, it's hitting the side, and then as it comes

around the corner, it produces a low pressure region here.

And that causes the movement, the building, to move this way. But then

means that the wind coming around this end starts to cause a little bit of

movement this side and low pressure. So we start to get this low pressure, low

pressure, low pressure, low pressure, and that causes this oscillation back

forth.

For architect, the challenge is to come up with a shape that reduces those

vortices.

Okay, let's try this one.

This time the building is tapered like an elongated pyramid.

We're running at three times the wind speed of that very first model that we

saw. And the building's just not moving anything like this violently.

Because of the tapered shape of the building, the wind creates vortices of

different sizes at different heights.

Different parts of the building are trying to shake at different rates,

canceling each other out.

Jack Cermak's wind tunnel allowed city skylines around the world to grow taller

and more safely.

Because of the wind, the Shanghai Tower is tapered, but it also has a

distinctive twist, one that reduces wind loads on the building by 24%. The

twisting of the building is a great example for engineers that can combine

creative architectural design with good engineering.

To accentuate this, architects implement a notched V across the entire length of

the building.

Once you have this brick, the V, you can actually read.

But the tapering, the twist, and the notch also brace the building against

wind.

of the building helps the aerodynamic the twisting helps and the notch helps

at the same time the tapering also lowers the center of gravity of the

that gives us more stability the lower the center of gravity the more stable

building is but the shanghai tower faces a natural force

even more destructive than high winds earthquakes

Of course, we're not only designing this building for typhoon, we know up to 120

miles per hour, we know. We also have to design it for significant and severe

earthquakes.

So, how do you build China's tallest building to withstand an earthquake in a

level 3 seismic zone?

Engineers look to neighboring Japan to make the impossible possible.

China's tallest skyscraper is the Shanghai Tower.

Built in a level 3 seismic zone, engineers must design a building 2 ,000

high that's also able to withstand Mother Nature's most brutal force,

earthquakes.

To overcome this daunting task, engineers look to neighboring Japan for

inspiration.

As the most seismically active country on the planet, Japan's earthquakes have

collapsed countless buildings, but traditional pagodas somehow remain

The secret to the pagoda's survival is hidden inside.

The typical pagoda consists of five floors.

Its floors have the ability to move independently of each other.

When an earthquake strikes, its snake -like pattern keeps the center of

more upright than a rigid building wood.

And the wooden joints that support each floor are made up of several separate

components. so each part can slide and move. The friction the parts create acts

like a shock absorber and softens any movement.

Today's engineers are taking the Pagoda's innovative earthquake -proof

and giving it a 21st century spin.

The Shanghai Tower's structure is divided into nine vertical zones around

central composite steel and concrete core.

To further strengthen the tower, huge perimeter columns and outriggers have

attached to the central core.

The core is just like the main chunk of your body, and the two whole columns,

the exterior column outside is like the steeple. And this steel truss member is

connecting your body.

and the column giving you a much better stability for the building to resist

earthquakes. The earthquake -proofing measures extend from the base of the

to its tip.

Here we are, coming up to the 125th floor of the tower, which is one of the

important rooms in the building.

You can see we have 1 ,200 tons of steel blocks.

being hung four stories above us.

So why are engineers taking up valuable floor space with a steel block that

weighs the equivalent of 600 four -door sedans?

Engineers look to a groundbreaking building in Boston.

The John Hancock Tower was completed in 1976.

But immediately upon completion, The building perilously swayed with the

Engineer William LeMessure came up with an ingenious solution.

What I've got here is a very simple model of a skyscraper. It's a beam

structure going up several stories.

Turning a handle at the base of the structure mimics an earthquake.

You do have this problem with sway.

Le Mejure tried to counteract the building's sway with two steel boxes

the 58th floor, each filled with several hundred tons of lead.

You have to imagine this is an 800 -ton weight that I'm lifting up onto my

skyscraper now, and I'm just going to tie it to the top of my structure.

The tuned mass damper, or TMD as it became known, had a dramatic effect.

It's amazing.

The structure is hardly moving.

I mean, it's quite phenomenal.

The principle is simple.

As the building starts to sway, the damper travels in the opposite

balancing the overall building.

It's amazing how much of an impact it has.

Without tuned mass dampers today, we just wouldn't have any of the kind of

structures that we have. The Shanghai Tower's engineers have taken LeMessure's

damping system to a whole new level.

Without these two mass damper, we have to use a lot more structural steel and

material to stiffen up the building.

Despite taking up five floors and weighing over 1 ,000 tons, the Shanghai

Tower's tuned mass damper actually makes the building cheaper and lighter to

construct.

After 15 years of planning and seven years of construction, engineers

China's tallest skyscraper in 2016 with the 2 ,000 -foot -high Shanghai Tower.

By drawing on innovations of the past and making groundbreaking discoveries of

their own, the engineers of the FAST telescope and the Shanghai Tower have

created China's biggest structures and some of the largest on the planet.

They've made the impossible possible.

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