After decades of work,

NASA's James Webb Space Telescope or JWST

is about to start its million-mile journey.

The Hubble Space Telescope, launched in 1990,

opened up new windows on the universe.

But scientists expect that JWST

will reveal even more,

revolutionizing our understanding of the cosmos,

and perhaps bringing us closer

to answering the age-old question are we alone?

The whole launch date is gonna to be filled with emotions.

It's an engineering marvel

that we as humans, we have never done this before.

I feel very nervous but excited

and just ready to go.

- I mean, there's so much riding on this telescope.

It's been decades of work

that's gone into it.

It's taken us a long time to get here

but man, we're so excited,

we're so ready for this to go.

This will be a transformative facility,

and it will show us so many things

that we just haven't seen.

JWST is the most powerful

space telescope ever constructed.

With a mirror almost three times wider than Hubble's,

it'll be able to see objects 10

or even 100 times fainter.

This is the biggest telescope

that has been built in space,

and because of the complexity of the design,

this is no doubt the most complex machine.

And it is magnificent.

JWST's mirror is 21 feet wide,

and made up of 18 different sections

that fold up tightly for launch like origami,

and will need to unfold perfectly once in space.

We're not just talking about having to develop

lightweight mirrors, but we need 18 of them.

They all have to match each other

such that they can be aligned

to a degree of accuracy

that's about a 10,000th of a human hair.

While humans see the world

through visible light,

there are many wavelengths invisible to the human eye,

such as X-rays, and infrared.

Sensing infrared light,

which can be detected in the form of heat,

JWST will be able to peer through dense clouds

of space dust that block visible light

so it can reveal previously hidden secrets

of the universe, like early galaxies

over 13.5 billion years old,

and the formation of stars and planets.

And because JWST

is an incredibly sensitive infrared telescope,

its scientific instruments and detectors need

to be kept at extremely cold temperatures

to suppress infrared background noise,

and function properly.

To help JWST keep its cool,

scientists built a sun shield

about the size of a tennis court,

nearly 70 feet across when deployed.

Radiation from the sun travels through space.

It doesn't care about the fact

that the telescope is far away.

And so we have to keep the mirrors

and the instruments in constant shade

and that's what the sun shield is for.

About five days after launch,

they'll start to expand the sun shield.

Once that's complete,

about 10 days after launch,

they'll start to unfold the mirror.

It'll take 30 days

and a million miles for JWST to reach its destination.

Then, it'll start the six-month cool-down

and calibration process.

If all goes according to plan,

JWST will commence its scientific operations

in June 2022.

And scientists are excited to see what it finds out

about the early universe and the first galaxies.

We're gonna see so many points of light

from different distances,

and that is in itself going to be a revealing moment

in how rich the universe truly is,

and how much is actually going on out there.

With Hubble, we pushed the boundaries

to a few hundreds million years

after the Big Bang.

JWST will look past that

and will be able to cover the very, very early phases

when the first stars appear,

when the first galaxies are assembled,

and the universe that we see today is shaped.

It should also reveal the evolution

of stars and planets.

JWST's infrared instruments will be able to peer

through the kinds of dense dust clouds

where star and planet formation begins.

So if we can understand how other planetary systems

out there form and where they form,

it's gonna be totally revolutionary.

We can track its history.

So this has profound implications

to understanding how our solar system came to be.

And sense the atmosphere of exoplanets.

With JWST, the infrared light allows us

to see water vapor in the atmospheres of exoplanets

but also, we can see things like methane

and carbon dioxide.

And depending on the type of planet

that we're looking at,

we can actually measure how much of these molecules

are in the atmosphere.

And that composition can tell us

whether there's any indications

of the elements of life

that could be possible on these exoplanet atmospheres.

I think we'll be surprised how strange

and different those planetary systems are.

Will we even recognize life?

We don't know.

I think that the whole point of going

to all the trouble of building a telescope

as big as JWST is because it provides us

with a brand new way to look at the universe

and every time humanity has looked at the universe

in a new way,

it has been transformative

as it has been surprising.

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