Unveiling the Engineering Marvel Behind the James Webb Space Telescope

It’s been almost two years since we first marveled at the breathtaking images captured by the James Webb Space Telescope (JWST).  As the mission progresses, we continue to unravel the intricate engineering behind this groundbreaking telescope. At the heart of its design lies a remarkable feat of precision and innovation – the hexagonal mirrors coated with gold, a symbol of excellence and ingenuity in space exploration.

Crafted by some of the best aerospace companies in the world, including Coherent, these hexagonal mirrors are not merely a decorative feature but a crucial component that enables the JWST to peer deep into the cosmos with unprecedented clarity.  While the shimmering gold coating adds to its iconic allure, the real magic lies in the meticulous craftmanship and cutting-edge technology employed in their creation.

Contrary to popular belief, the mirrors themselves are not made of gold, but of beryllium, a lightweight and resilient metal capable of withstanding the harsh, cold conditions of space without becoming brittle. Coherent undertook the monumental task of polishing these 18 mirrors to near perfection.

The Evolution of the Mirrors

The journey of these mirrors from raw material to space-ready components involved a series of intricate processes. Initially, the mirrors were precisely polished to achieve a curvature accurate to one millionth of an inch.  Subsequently they were subjected to the extreme cold temperatures resembling the environment of deep space, to measure how much the shape changed when cold. The measurements were used to calculate changes to the mirror on Earth that would result in a perfect shape in deep cold space.

A second round of polishing was then meticulously carried out to compensate for these alterations, a testament to the Coherent commitment to precision engineering. This deliberate deviation from Earth temperature underscores the meticulous foresight and planning required to ensure optimal performance in the unforgiving environment of space.

The choice of gold for the mirror was not arbitrary but a strategic decision rooted in its exceptional ability to reflect infrared light.  Through a process known as vapor deposition, Coherent applied a thin layer of gold coating measuring only a few atoms thick – a mere fraction of a human hair.

Due to the delicate nature of pure gold, the coating was fortified with a protective layer to overcoat and safeguard the mirror against potential micrometeorites, highlighting the unwavering dedication by Coherent to support the longevity and durability of the James Webb Space Telescope.