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How much gold is in the James Webb Space Telescope? (Synopsis) [Starts With A Bang]
“Hey, if our eyes could access the infrared part of the light spectrum, the sky would be green and trees would be red. Some animals see in completely different ways, so who knows what colors look like to them. Nothing is really how we perceive it.” -Wendy Mass
If you take a look at the James Webb Space Telescope, the most visually striking feature of all is the gold mirrors. Yet gold would make an absolutely terrible material for constructing these mirrors! For very sound scientific reasons, the vast majority of these mirrors are made out of beryllium, not gold, and gold doesn’t even enter the equation until after the first and second polishings.
Only after being machined, polished, cooled, re-polished and thoroughly tested will the gold coating be applied over the beryllium mirror. Image credit: Ball Aerospace.
But gold is a fantastic material for reflecting infrared light, and so getting a uniformly thick gold coating on these mirrors in imperative. When all is said and done, a surface area of 25 square meters — the equivalent of 269 square feet — must be coated in this thin gold coating, which itself must be protected from the environment.
The 18 segments of James Webb in the laboratory, after completed assembly and all coatings have been applied. The gold is visually striking, but there’s very little of it. Image credit: NASA / Chris Gunn.
How much gold does this take? The scientific story of the mirrors holds the answer!
Source: http://scienceblogs.com/startswithabang/2017/04/05/how-much-gold-is-in-the-james-webb-space-telescope-synopsis/
