The James Webb Space Telescope’s Near Infrared Camera instrument used a specialized pupil imaging lens to take this “selfie” of the 18 segments of the primary mirror. Credit: NASA

Over the last week, the James Webb Space Telescope began detecting its first photons of light as it begins a three-month process to align its mirror segments.

On Feb. 3, 2022, starlight was detected by the Near Infrared Camera, or NIRCam, which NASA said was the first of many steps to perfectly align the 18 hexagon segments that make up the 21-foot (6.5-meter) diameter primary mirror.

Teams have rehearsed and practiced algorithms for alignment with a 1/16 scale model of the space telescope with completion of that process expected in seven sequential phases over the next three months.

The telescope’s 18 primary mirror segments are required to match one-another within a wavelength of light approximately 50 nanometers. Teams will work with images during this timeframe strictly for the purpose of preparation of scientific investigations, comprehensive aesthetically pleasing detailed images are expected later this summer.

Now that the deployment of the James Webb Space Telescope mirror segments are complete, instruments on and fully operational, Scott Acton and Chanda Walker of Ball Aerospace and Lee Feinberg of NASA’s Goddard Space Flight Center identified further steps that will be taken to prepare and calibrate the telescope to do its job.

This image mosaic was created by pointing the telescope toward a bright star. Because the 18 segments of the primary mirror are not yet aligned, there are 18 individual, and blurry, images of the same star. Credit: NASA

The steps needed in the aligning process are:

Segment image identification
Segment alignment
Image stacking
Coarse phasing
Fine phasing
Telescope alignment over instrument fields of view
Iterate alignment for final correction

On Feb. 11, NASA released images of the first star the telescope was pointed toward. It appeared as “18 randomly organized dots of starlight” as the photons made their way into NIRCam.

NASA said the team will need to identify dots of starlight in all of the 18 primary mirror segments — part of the mosaic created by pointing the telescope at an isolated star in the constellation Ursa Major known as HD 84406 — with the corresponding primate mirror segment that captured it.

Technicians will need to focus and align the blurry starlight until the images become a single star, a task that is expected to be completed over the next few months.

“The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam,” Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy for the University of Arizona, said in a NASA news release.

The James Webb Space Telescope is the most powerful and largest space telescope ever built and is designed to help solve mysteries of our universe and solar system. It launched on Christmas Day, 2021, and is now in its final orbit at the Earth-Sun Lagrange point about 1 million miles (1.5 million kilometers) away from our planet.

Video courtesy of NASA

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