Obviously Hubble the person is already dead, but the Hubble telescope will die one day.

And we have to both be mentally and astronomically prepared.

Something will wear out on Hubble space telescope basically.

Either calibration lamps or ...

...some of the fuel to change which direction it's pointing in, it will eventually stop working.

We will no longer be able to get images from Hubble.

[Sunrise over the Hubble space telescope...

...illuminating the golden solar arrays, those arrays to be retracted for the final time a few hours from now.]

Nasa, ESA, as a new space telescope, have got a new Hubble in the pipeline.

It's called James Webb Space Telescope and...

...this is what it looks like. It's infrared not optical, unlike Hubble so it's not really a true follow-up...

...because Hubble looks in the UV and the optical and an infrared, whereas James Webb will look out the very far...

...infrared. James Webb will be at the Lagrange 2 point, so I know that Sixty Symbols is done a...

...Lagrangian video before but basically a Lagrange point is a stable point in a two-body system.

So we have the sun and we have the Earth...

...going around the sun and basically there are five points in those orbits at which, if you put something...

...it wouldn't move relative to the Earth and Sun.

So it would stay where it was. So L2 is sort of beyond Earth, away from the Sun. And basically it will have a...

...365-day year, the same as the Earth, but it will be orbiting further around. It will be...

...launched in an Ariane 5, which is a really really successful ESA Rocket.

[Allumage EAP, décollage]

And then they're gonna give it a little bust. And then they'll get it enough energy to get to L2...

...but really really slowly. So what they'll do is...

...is kind of like going up a hill, if you will. So they'll give it enough energy to boost it up the hill...

...but so much so it will slow down, slow down, slow down,...until it reaches the very top, at which point it will stop.

Just like it was a really good putt?

Yeah! Like a really, really good putt, yeah.

And it'll just sort of stop at the edge and then just fall in.

In that time, the antenna will fold out, so it can talk to Earth. And then the whole thing moves upwards as well...

...and it's called a spacecraft "bus", they call it.

The whole thing will move up and make room for all of the equipment down below.

The sun shield will all fold out as well.

This is this huge tennis-court sized, five-layer, intricate sun shield.

This, which we call the secondary mirror, ...

...so as light comes in here, bounces off here, bounces onto the secondary and then...

...into the center, where it's detected. That will also be up here during launch and will get folded down to the right position.

The mirror itself, so this segmented array, ...

...will also fold out from being folded up inside the rocket.

So what they've had to do is they had to design the shape of the mirror...

...so that it is the wrong shape at room temperature...

...but by the time that it gets to, like, the vacuum of space it will cool and warp to the right shape.

It feels like they've made this too complicated, like they seem, like, they've been too ambitious. Am I wrong?

I get that feeling as well, but I think it's because I...

...I'm not an engineer, a space scientist engineer, so I can't...

...comprehend what is too complicated, you know. Let's leave it for the rocket scientists to tell us...

...you know, what's too complicated. They have such belief that this will work.

So the astronomical community, you know, has faith in them and says...

"OK, well, this is what I want to do with it". There's...

...a huge long list of things that could go wrong. It could...

...just blow up being... trying to be launched.

The antenna couldn't even fold out. The sun shields might not deploy properly.

The mirror might not fold out properly, the secondary mirror might not fold out properly, the whole thing might not move up, it might jam.

Like, the cryostat, to cool everything, might not come on.

The electronics might be fried, it might get shook up too much than it might not work.

I mean, it's kind of terrifying trying to list everything that might go wrong, but also exciting.

Because they've had to...

...think about "how can we stop that from happening?"

There's about 10...

...brand new technologies that've gone into the JWST that haven't been tested before.

Everything's already built. You know, everything's being tested repeatedly...

...at NASA Goddard, which is in the Washington DC area.

They're vibration testing, they are testing the solar shields, how they pull out.

Someone said to me that, the test they've seen, it happened through the day, but it took two weeks for the solar shields to fully...

...open up, they said it was like watching paint dry. Okay, you'd go for lunch, come back, and they were like they haven't moved at all.

It's going, undergoing, so much rigorous testing to make sure that everything can stand up to the launch and...

...fold out in the, y'know, the sort of situation that it needs to.

Hubble was optical and UV. It had...

...stuff that it could specifically do. But it's limited. It can only see so far, and that's because, obviously...

...if you imagine stars and galaxies are always giving us optical light, ...

...the further away they are the more that light is redshifted and so Hubble can't actually see the very distant galaxies.

Because there's nothing really in the optical...

...wavelengths that it can see anymore.

So we have to look in the infrared.

I've printed out these to show you... So this is...

...the optical image of the Eagle Nebula, taken by Hubble. It is my favorite Hubble image, it is beautiful.

It's of a star forming region in the Milky Way. You can see all the dust clouds. It's absolutely beautiful.

On your...right?... yeah, OK...

...is the infrared image from Hubble as well.

And although the optical one is more sort of visually spectacular...

...the infrared one is more scientifically spectacular...

...because you can see through all the dust and the gas that's in this nebula, and so you can...

...learn more from the infrared image than you can from the optical.

Obviously, to get enough light from an object you have to stare at it incessantly and...

...the idea with James Webb is that it's got such a big mirror...

...(6.5m, as opposed to, you know, Hubble's 2.4)...

...that you don't have to stare for very long at all. So that, uh... one of the...

...quotes I remember was that if you took the Spitzer Space Telescope, which is...

...infrared as well... it did an entire survey of...

...galaxies, and it took something like 550 hours of observing time...

...that's just actually staring at the sky, that's not including all the time it takes to repoint the telescope.

If you end up doing the exact same survey again with James Webb, it would take 30 minutes!

The other thing it's gonna be able to do...

...or people hope it will be able to do, is to detect the first signs of life in our universe...

...y'know, beyond our own planet, obviously.

I mean, I'm not talking about sort of you know contacting ET or little green men here.

What I'm talking about is...

...biosignatures.

Y'know, this is the idea that you will be able to detect in that atmosphere, say, water or oxygen or...

...carbon dioxide.

Something that, we know, on Earth...

...is a signature that life is here.

The way that they've detected exoplanets in the past is to have...

...the exoplanet's star here... if you're sort of the Kepler Spacecraft, which is the one that's been detecting exoplanets...

...and I am the star... then what happens is, you're observing light from me, and you're like "Yep...

...there's a star there, there's definitely a star there". And then a planet moves across...

...my face and basically it will produce a tiny little dip...

....in my brightness.

In which case you'd be like "Oh! A planet there!"

What they do now is they'll wait for it to transit...

...and they'll wait for the the light from the star to pass through a teeny tiny bit of the atmosphere of that planet...

...and then they will take that light and split it into its rainbow, into its spectra.

They'll take off the light from the star and they'll be left with the absorption spectra of the atmosphere of that planet.

Even if we were very confident that we had detected signs of life in an atmosphere...

...and we said "OK, this is definitely, sort of, like Earth"... the most Earth-like we could possibly ever find.

Say it's a star exactly like the sun, and it's at Earth's size and at Earth's, y'know, radius planet and everything...

...and it's got ozone, and it's got hydrogene, it's got CO2, everything...

...it might be 10,000 light years away.

And if we were ever gonna have a conversation with these people...

... I call them people... with this life...

...if they were intelligent life...

...it would take us 10.000 years to send a signal and for them to receive it, and 10.000 years to come back.

So it would be a 20-thousand-year wait for the other side of the conversation.

In the paper, there's, you know, the most Earth-like planet every six months.

And that'd be the most Earth-like from its mass or from its radius or from the distance it orbits around its star...

I that'll be the most earth-like from its mass or from its radius or from the distance it orbits around its star or the fact

...or for the fact that the star is the same as the sun.

We've never really found one that fits all of those...

...criteria at once. It's pretty scary because it won't launch till October 2018...

...but they already have science proposals in. If you want to do something very specific...

...that's your science, the call for proposals is November, this year!

So everybody is already starting to think...

"What will I do? How will I observe this? How long will it take me?"...

...'cause you have to put all that in the proposal before someone decides "Yes or no, you don't get time"...

...before it's even launched.

Before it's even gone to the launch site, like, it won't even be in French Guiana before people put in...

...telescope proposals.

I bet those people are going to be nervous when they'll launch it, too?

Yes! Definitely! If your, sort of, scientific career future prospects of...

...you know, depend on you getting the James Webb Space Telescope time, ...

...you need that thing to work.

...portion of the spectrum.

We feel right now that there's probably no real science that we can do with the wide-field camera at this time.

And I'll stop there.

The thing about Hubble is that it was launched into low Earth orbit and...

...it was always intended that it would be visited by astronauts. And so a few years later one of five...