Before the Hubble Space Telescope launched in 1990, we didn’t know how old the universe

was.

We had never seen a planet outside of our solar system.

We didn’t even know about dark energy!

Hubble taught us a lot, but it can only see so far, and in so much detail.

To see farther, all the way back to the formation of the very first stars and galaxies (what’s

known as the universe’s first light) we’re going to need a bigger telescope.

And that is exactly what started the largest, most expensive, and most challenging space

engineering project humans have ever attempted: the James Webb Space Telescope.

It’s been over 30 years since work on this massive machine began, so when will it be

ready?

And how close are we to using it to see the universe’s first light?

Since its beginning, the James Webb Space Telescope has involved thousands of scientists

and engineers all over the globe.

But all this work raises the question, what’s so important about creating a telescope that’s

able to see the universe’s first galaxies?

The Hubble Space Telescope has been absolutely revolutionary in changing the way that we

understand the universe.

But we're really missing a key piece of the puzzle.

We're missing the very start of how galaxies got started

When you know how they formed, when you understand the situation

that this galaxy arised from, you understand the evolution, the forces at work, and a better

picture of what the universe was like back then.

It'll help us do things like predict what will happen to the stars and galaxies in our

universe further on.

What's going to happen at the end of everything?

And if finding out how the world ends isn’t enough for you, Webb will be able to do a

whole lot more.

The search for life is one of the big things that we're doing at NASA right now.

And it's really exciting.

And Webb is going to make, I think, really groundbreaking discoveries in exoplanet science.

One never knows.

We could get lucky.

Now, personally, do I hope we find signs of life with the Webb Telescope?

Yes, of course.

It would be awesome.

Really Webb is a multi-purpose observatory.

It will observe everything from the planets in our own solar system out to the most distant

objects we can see, and everything in-between.

And step one in building this, it turns out, starts with these.

If you've ever been with a bunch of engineering-type folks, when you sit in a meeting where you

want to talk about some kind of structure, people grab whatever's nearest to them.

I got a water bottle and I'm sticking it on top of my phone and, "Hey, here's a telescope,

and this..."

It's crazy.

So I just decided to build my own silly little model of JWST and brought it in and said,

"Look.

Instead of a cup and a phone, can we please just use this model?"

So how do we engineer THIS to see back in time?

Well, it has to see in infrared.

I’ll let Dr. Straughn explain.

So if you think about, for example, the Hubble Ultra Deep Field.

In this deepest image of the universe that we've ever had, we're able to see very very

distant galaxies, and if you pick out what the most distant ones are you'll

see that they're these little tiny red blips.

They're so far away that the expansion of the universe has caused the light from those

galaxies to literally be stretched into longer wavelengths.

And longer wavelengths mean redder light.

That's why we built the James Webb Space Telescope to be sensitive to the infrared: so that it

can pick up where Hubble left off and really complete that very first picture to look at

the very first stars and very first galaxies. And Webb’s ability to see in infrared really

relies on 3 main things.

Its mirror, its sunshield, and its orbit.

Let’s start with the mirror.

It may not look big here, but that mirror is HUGE.

6 and 1/2 meters in diameter to be precise.

The reason why it's so big is really because the very first stars and very first galaxies

that were ever formed, they're very far away and they're very dim.

We're trying to collect one photon approximately every second.

We're counting individual photons.

So we need to be able to collect all of that light.

Now, the reason the mirror is gold is that it reflects infrared, making it easier to

focus that distant light down to the instruments.

But there’s a problem, the sun also emits infrared.

Which brings us to the sunshield.

This part is also huge, about the size of a tennis court.

So part of the job of the sun shield is literally to block the light from the sun from reaching

the telescope and messing up all of the good work that it's going to do.

It allows the telescope to operate at a temperature that is about 30 degrees kelvin.

Room temperature is about 300-ish kelvin.

So we are going very, very cold.

And finally, the orbit.

The James Webb Space Telescope is going far.

Really far.

1.5 million km away from earth, to a place called the second lagrange point, or L2.

So here's the sun.

You have the Earth here.

L2 is here.

When you go out to L2, you don't have the Earth and the sun filling half your sky.

That's why we can use the sun shield to kind of cover them up so that all Webb sees is

the dark of space and be able to do its mission.

So, we need to launch all of this enormous, sensitive equipment on a rocket into space,

over a million kilometers away.

Which complicates things further because rocket launches are basically well-controlled explosions.

In order to survive that explosion, it has to be designed to be very robust and strong.

That coupled with the fact that JWST is also fairly large means we have to design it very

carefully to fit inside the rocket, then deploy it.

It has to be right when we launch it.

We have to test everything to make sure that it works correctly once it's in space because

we can't go fix it.

That’s what makes this project so unique; they won’t get a second chance–unlike

Hubble, which was serviced by astronauts 5 separate times.

Webb has to be perfect on the first try, so understandably, that’s taken some time to

achieve.

The James Webb Space Telescope was first scheduled to be launched in 2007, and was budgeted at

500 million dollars.

But as construction progressed and testing began, that launch date and budget have changed.

A lot.

This really is engineering at the extreme.

It's pushing the edge of what's possible.

As a scientist that's going to depend on this telescope for my future research, to hear

of another delay was sad, it was disappointing.

But that's the reason we test because we don't want these things to happen once we're in

space.

And that brings us to where we are today.

With construction mostly complete, all that’s left are the final testing stages leading

up to the launch.

The sun shield and the spacecraft element are currently undergoing thermal vacuum testing.

And then after that we'll undergo some more tests, and then we will ship the whole observatory

down to South America in French Guiana to prep it for launch.

Once the telescope launches and is on its way to L2, it will start to unfold in space.

The entire process will take about two to three weeks.

I don't expect any of us are going to be getting much sleep for that time.

The thing for me that is maybe the most scary is the deployment of sun-shield.

There are 100s of different individual sort of movable parts that have to happen during

that deployment.

Between it deploying and being fully tensioned up, the position requirement that it has to hold

on orbit in space is about this much.

My job is to make sure that this thing, through its manufacturing, through installation, through

all the testing, and whatever happens to it on orbit, that it holds to this much slop.

After the telescope is fully deployed there's still a few key things we have to do.

We're going to tweak the mirror in order to make it perfect.

And then we have science instruments, cameras, and spectrographs that we turn on one at a

time, and we bring those up to working order.

This whole process takes a few months after launch to get ready.

Only then, after testing, launch, and deployment, can we discover the mysteries of our beginnings.

So, how close are we to seeing the universe’s first light?

Well, JWST will be launching in spring of 2021.

So about the summer to fall of 2021 is when we'll start getting those very first pictures

back, first light.

Our current theories in astrophysics tell us that we should be able to see those first

galaxies with Webb.

Of course we don't know yet, we won't know until we look.

But if the theories are right, then I think we should see the very first galaxies something

like a couple years from now after Webb is launched and starts taking its first data.

Astronomy really gets to the heart of what it means to be human.

It's asking these big questions that humans have always asked, you know, "Where do we

come from?

How did we get here?

And are we alone?"

I think we'll answer questions that we haven't even thought to ask yet, and that is one of

the most exciting things about any big telescope like this.

We are creatures of curiosity and of wonder.

This is an expression of it, I think, the highest level that we can achieve.

For more episodes of how close are we make sure to check out this playlist, and let us

know in the comments what you want to see us investigate next!

Thanks for watching!