There is a lot of hustle and bustle because the integration is in full process.
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Just look at NASA's James Webb space telescope.
Its gold mirrors are definitely
its most stunning feature. And yeah, that's real gold.
Humans have long history of searching for gold
and using it in their most prized possessions. These mirrors weren't gilded
to make them pretty. There isn’t’ even all that much gold
about 5 men's wedding rings-worth over the 18 mirrors.
So I wanted to see for myself, why does it make sense to use a
microscopic layer of gold on these mirrors?
Why Does Webb have Gold Mirrors?
So our everyday mirrors tend to use silver or aluminum
as their reflective material. One of the major differences
between our earthly mirrors and these fancy optical mirrors is the position
of the reflective material. Look at the side of this this small mirror.
It has the glass on the front, and the metal
coating behind it. That glass actually traps a tiny amount of light
and creates what we call a ghosting effect. So the clearest reflection
we can get actually have that metal coating on the front.
Dentists and hygienists also front-surface mirrors
to get an accurate look at your teeth.
The position of the reflective coating might make a sharp observation, but the kind of metal also matters too.
There are a couple of reflective materials that really excel at reflecting
infrared light, which is how Webb will observe.
Aluminum reflects 85% of that wavelength of light
, silver up to 95% and gold up
up to 99% of all the infrared light that it encounters.
But gold is special, and I can show you using
the rings that I typically wear. This one is gold.
And this one is made out of silver.
And in the presence of the right chemicals, these two chemicals react differently.
I think, actually, it's a little easier to
show you, all of this with this spoon. My mom
surprised me by pulling out this whole tub of silver! Not tub, it came out of a box
so I'm able to demonstrate sort of on a bigger surface, how silver can react
differently using an egg.
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Smoosh that in.
We've got nothing. We've got nothing.
So what we have is a really fast reaction between the sulfur in the egg
and the silver, and it creates a new thin layer
on the spoon of silver sulfide.
Silver might be great at reflecting infrared light, but it tarnishes so easily.
Not only does gold reflect more infrared light,
but it is also one of the most unreactive metals.
It is too durable to oxidize and decay in space.
And it is certainly
Webb's best chance at seeing the cosmos!