The James Webb Space Telescope takes a selfie and takes a big step towards its first “real” image – TechCrunch


A device as complex as the James Webb Space Telescope takes a bit of time to get up and running, so although it entered orbit late last month, it’s still working through its start-up process. Today’s milestone is a big one, with Webb spotting his first star, 18 times more. And it took a selfie to celebrate.

As you probably know if you’ve taken a look at the coverage of this massive orbiting telescope over the many years of its development, assembly and deployment, the Webb is essentially a nest-shaped collection. bee has 18 mirrors, which help it capture large amounts of infrared light. of his chosen target.

But each of these mirrors (along with the secondary mirror in front and many other components) must be fine-tuned so that the image reflected in it matches and overlaps that of the others.

“We know that the primary mirror segments aren’t aligned, so they’re actually acting like 18 separate telescopes, and we’re expecting to see 18 separate images, one for each mirror, which are a bit blurry at this point because we we haven’t lined up for anything targeted,” Lee Feinberg, head of optics at the Webb, said in a NASA video that explains it all better than I ever could.

Think of it like cartoons where a character wakes up after being knocked out and sees the world double or quadruple, then gradually aligns those images. In this case, of course, the telescope is in the middle of space, so the best (and pretty much the only) thing to look at safely is the stars.

The team needed a star that was distinct and not surrounded by other stars of similar brightness. They chose one called HD 84406 in the constellation Ursa Major, on the cosmic bear’s neck frill. For those of us more familiar with the Big Dipper, if you look at the two stars that make up the top of the dipper itself, HD 84406 is roughly equidistant to the right along that line.

Pointed in the general direction of the HD 84406, the Webb took 10 frames each in 156 slightly different directions, resulting in 1,560 shots and 54 gigabytes of raw data.

Picture credits: Nasa

“This initial search covered an area the size of the full Moon, as the segment points could have been so scattered across the sky,” Marshall Perrin, a scientist with the Webb team, said in a press release. Nasa. “And we found the 18-segment light very close to the center early in this search! That’s a great starting point for mirror alignment.

After six hours of processing, they were able to locate the same star in each of the telescope’s 18 mirrors and stitch them together into a single image (top) that shows how the array should be realigned. As noted by Perrin, it’s entirely possible that one or more of them were much farther from center, requiring a longer and more intense mirror correction procedure. But they’re all clustered near the center, which means the mirror deployment went very well.

It’s not the only camera system on board the Webb, and not the only setup process by any means either. It will still take some time to get the first “real” image, but today’s success shows that the infrared camera and primary mirrors are working as expected, but not yet at full capacity.

Fortunately, another instrument was functional enough to obtain the most crucial content: a selfie.

"Selfies" of the Webb Telescope showing its 18 mirrors.

Picture credits: Nasa

We’ll cover major milestones like this, but if you want to follow the Webb’s every move, keep an eye on the dedicated mission blog.

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