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[MUSIC PLAYING]

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Mirrors on a telescope are often
coated with some kind of metal

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in order to reflect as
much light as possible.

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Now the type of metal depends
upon the kind of light

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the telescope is looking at.

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The James Webb Space Telescope
is looking at infrared light.

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And for that, gold
is the ideal choice.

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To find out how the gold is put
onto the mirrors of the James

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Webb Space Telescope,
we are here

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at Quantum Coating in
Moorestown, New Jersey.

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So, Ian, how much gold
are we talking about?

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Enough for a ring?

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Not even that.

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Well, it depends on how big
your ring is, of course.

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But the thickness of the coating
is almost unimaginably small.

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To give an example,
this piece of paper

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is about one
thousandth of an inch.

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We could take 1,000
gold coatings,

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stack them all side
by side, and they

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would be the thickness
of this piece of paper.

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In terms of the amount
of gold that we need,

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it comes to three
grams of material.

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And three grams looks like--

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Three grams-- I have it here.

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--this.

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Wow, that's amazing considering
how big the mirror is.

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That in mind, when it's
spread out thin enough,

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it covers the whole
surface of the hexagon.

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When you apply the coating, are
we talking about a paint job?

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No, this is all
vacuum deposition.

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It happens in a chamber
where all of the air

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has been sucked out
to create a vacuum.

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Then we vaporize the gold.

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We create a cloud of vapor.

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And that vapor condenses on
the surface to form the film.

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And why do you choose to
apply the gold that way?

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That's the way to get
the maximum reflection.

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Spray painting or
other techniques

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wouldn't give us
enough reflection.

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And can we actually see the
gold being applied to a mirror?

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Sure.

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Ty is the guy who operates
the cutting machine.

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He'd be happy to show
you how that works.

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Hey, Ty.

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Hey, how are you doing, Mary?

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I was told that a coating
process is about to start.

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Sure, we're about to
start the coating soon.

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Can we tag along?

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Sure.

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OK, see, what we're
doing here now-- we're

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preparing the
mirror for coating.

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Cleaning the mirror of any
contaminants or any particles

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that could be on the mirror.

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So, Ty, what's
going on here now?

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OK, well, now we're putting
on the shield and the mask

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for the mirror.

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A coating can not be beyond
a certain area on the mirror.

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So you want the gold to
just be on the surface.

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Nothing on the
sides or anything.

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Right.

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There's a bevel also on
the edge of the mirror.

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We don't want any coating
on the bevel either.

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How long is it's going to take?

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Maybe an hour in total.

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But I understand there are
no cameras in the chamber.

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Can we see what's going on?

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We can take a look
inside our viewport.

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We see the part rotating and
we can see the glow dispersed

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right now.

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So, Ty, we couldn't
show the actual company

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specific equipment that was
used to apply the coating,

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but we get to see the
gold-coated mirror,

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fresh out of the chamber.

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Yeah, that's neat.

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Look at it.

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The mirror is coated.

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Now we're all complete.

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And we're ready to ship
it off to the customer.

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And they can begin
their testing.

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Well, thanks so
much for guiding us

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through your coating process.

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It was fascinating.

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Well, not a problem at all.

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Well, as you can
see, gold isn't just

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a fashion accessory for the
James Webb Space Telescope

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but a critical addition
to making the telescope

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work its very best.

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Thanks for joining us
for another edition

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of Behind the Webb.

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[MUSIC PLAYING]

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