Webb Telescope reaches major milestone: All its light is in one place

Enlarge (credit: NASA/STSci)

Today, NASA shared an image indicating that it had successfully completed the image alignment stage of commissioning the Webb Space telescope. The Webb's primary mirror is composed of 18 individual segments and, as of today's update, all of those segments are aligned so that a single star shows up as a single object. While there are still several more focusing steps required, the path to commissioning the telescope keeps getting shorter.

Immediately after launch, the focus was on unfolding all the pieces of the telescope that had to be held in a compact configuration to fit in the launch vehicle. This process included reorienting and extending the primary mirror, lowering the secondary mirror into place, and stretching out the multi-layered sunscreen that helps keep the imaging hardware cold.

To the surprise and delight of many people, that all went incredibly smoothly. Since then, the focus has shifted to... well, focus. The Webb's primary mirror consists of 18 separate mirrors in a hexagonal array, each of which can be controlled separately. Initially, when the mirror was first unfolded, these produced 18 individual smears scattered across the secondary mirror.

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