James Webb Space Telescope Delivers Splendid Star Image as Mirrors Align

NASA reports Webb's critical mirror alignment process is coming along beautifully.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
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The "image stacking" phase of the Webb telescope alignment involves the creation of a single unified image out of multiple images. This is 18 segments stacked to show a single star.


When we saw one of the James Webb Space Telescope's first images earlier this month, it was made up of 18 versions of the same star coming from 18 different mirrors. On Friday, NASA shared a view of that star again, but this time as a single, shining object.

It's one thing to build and launch a big, complex, next-gen space telescope. It's another to shepherd it through a complicated deployment so it can take a proper look at the universe. Webb is in the middle of a multi-phase mirror alignment and it's going swimmingly so far. The goal is to get all of Webb's many mirrors working together as one.

The two most recent phases involved making minor adjustments in the alignment of the telescope's mirrors. "The completion of this process, known as segment alignment, was a key step prior to overlapping the light from all the mirrors so that they can work in unison," NASA said in a statement on Friday.

The Webb team posted a GIF showing the before and after images from the segment alignment. You can see how the star comes into sharper focus.

The next phase was "image stacking," which is pretty much what it sounds like. "The team activated sets of six mirrors at a time and commanded them to repoint their light to overlap, until all dots of starlight overlapped with each other," NASA said. That's how we got to the single-star shot.

The Webb team will continue to fine-tune the mirrors to "make the single dot of starlight progressively sharper and more focused in the coming weeks." The mirror-alignment process started in early February and is expected to last three months. Each successful step brings Webb closer to full operation.

Webb is a joint project from NASA, the European Space Agency and the Canadian Space Agency. It's getting ready to stare into the heart of the early universe. It was a long journey to get Webb off the ground and into space, one filled with delays and eventually capped by a dramatic launch in late 2021.

The space telescope has a star twinkling in its eyes, and that star will continue to be a guiding light as Webb's mirrors come together.