The James Webb telescope – the largest and most powerful device of its kind ever launched into space – has already provided breathtaking images of the early universe.
While the telescope itself is a technological marvel, one of its most aesthetically appealing elements is the 6.5-meter primary mirror, made of 18 hexagonal mirrors, coated in gold.
And yes, that’s real gold – about five men’s wedding bands worth of the metal.
We had a question: why? What is the reason the mirror is gold plated? Well, we have the answer.
Mirrors on a telescope are often covered with some kind of metal to reflect as much light as possible.
The type of metal depends on the type of light a telescope is looking at, and in James Webb’s case, gold was the ideal choice.
The telescope observes infrared – the type of light that comes from the deep cosmos.
From Paul Geithnerdeputy project manager for the James Webb Space Telescope at NASA, there are two main reasons why observing the infrared spectrum is crucial:
One of the reasons is that the ultraviolet and visible light emitted by the very first luminescent objects formed in the universe when it was young has been stretched by the expansion of the universe, so that it is visible to us today, more than 13 billion years later. , reached as infrared light. .
Another reason is that stars and planets form in clouds of gas and dust, and this dust obscures our view. Infrared light penetrates these clouds and allows us to see inside.
To support the telescope’s mission to observe infrared light, the mirrors are designed to reflect as much of the light as possible.
According to NASA’s Elements of the Webb series, there are a number of metals that perform exceptionally well at reflecting infrared light.
Aluminum reflects 85%, silver up to 95% and gold up to 99%.
Gold is also one of the most unreactive metals, meaning it is too durable to oxidize and decay in space.
To maximize the reflective properties of the metal, the gold coating is applied to the mirrors using a process called ‘vacuum vapor deposition’. Basically, the mirrors are placed in a vacuum chamber and a small amount of gold is vaporized and deposited on the mirror.
You can see how this fascinating process works in the video below:
So there you have it! Now you know why the mirrors of the James Webb Telescope are gold plated.