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we're at the high bay at northrop

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grumman where we are about to get a

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bird's eye view of the sun shield

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to tell us more about the sunshield

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which is actually made up of five layers

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of a material called captain we have

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andy tau he's the chief engineer for the

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sunshield

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andy tell us first of all what is the

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sunshield for well the sunshield's main

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purpose is to keep the energy from the

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sun from getting to the telescope j west

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looks for very faint basically thermal

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objects out in space it's important to

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keep things really cold so if we were to

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allow the telescope to heat up the

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warmth of the telescope itself would

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just swamp out the sensors and it

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wouldn't be able to see anything except

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its own heat

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the second thing is just to keep out the

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visible light also the visible light can

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get inside the optical train and cause

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all kinds of interference so we want to

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keep that out too

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now andy i mentioned before it has five

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layers of a material called campton

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before i ask you why five capped on

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cap time half done is essentially a

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space age plastic film material it's

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something that's been developed for a

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number of years and we actually use it

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in our thermal insulation material okay

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and five layers why is that five layers

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well

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six would be too many and four would be

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too few you've got this down yeah well

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it's actually uh has to do with

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the amount of energy that we need to

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reject from the sun the sun is putting

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in a certain amount of energy and we

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need to reject that and make sure it

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doesn't get to the telescope the

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sunshield is built so that there's an

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angle between each one of the layers so

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heat that comes off of layer one gets

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bounced out and actually gets rejected

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out the sides

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so if the spacecraft was down here we

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actually have a couple of holes in the

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sunshield that allow heat to come up

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from the spacecraft and get pumped out

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through the sides so the sunshield is

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sort of like a giant heat pump passive

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heat pump this is the not the flight

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hardware right this is actually just the

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test article that's right this is uh one

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of our series of development articles

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and a very important one it's full size

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and it's pretty close to flight but

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there's some important differences

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all right ready to come down

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oh boy

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these layers that you see right now

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actually will be coated with a vapor

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deposited aluminum okay and that

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aluminum which you see here on the

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underside of the thermal covers

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is uh

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99.99 reflective so that helps a lot

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when we're trying to bounce all that

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thermal energy out of the sunshield okay

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now the the kind of pinkish purplish

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part is actually a silicon layer and

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that's the one that's exposed to the sun

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that's right but we use the aluminum the

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super highly reflected aluminum

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everywhere else that we can to reject

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this silicon layer actually protects the

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sun shield during launch and when the

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james webb space telescope observatory

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reaches its destination one million

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miles from earth

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this silicone cover gets deployed thanks