Encouraging Webb Telescope Image Shows a Single Star in a Familiar Pattern

Encouraging Webb Telescope Image Shows a Single Star in a Familiar Pattern
Engineers have brought 18 dots of starlight into a coherent pattern. (Image: NASA/STScI/J. DePasquale)

A major milestone in the commissioning of the James Webb Space Telescope has been met, as engineers continue to bring the observatory’s view of the universe into focus.

Annotated view of the new mosaic image, matching the mirror to each dot.  (Image: NASA/STScI/J. DePasquale)Annotated view of the new mosaic image, matching the mirror to each dot. (Image: NASA/STScI/J. DePasquale)

We’ve seen these 18 dots before, but now they’re organised. Oh, how beautifully organised.

The $US10 ($14) billion Webb telescope is currently fixated on this single star, designated HD 84406, as engineers work to align its 18 gold mirrors. Eventually, these 18 dots will merge together to form a single image. At first, these dots were seen as 18 scattered, quasi-random spots, but now they’re oriented to match the honeycomb shape of the primary mirror, in a process known as Segment Image Identification, according to a NASA statement.

“We steer the segment dots into this array so that they have the same relative locations as the physical mirrors,” Matthew Lallo, systems scientist at the Baltimore-based Space Telescope Science Institute, said in the statement.

A selfie taken by the Webb Telescope, showing the hexagonal pattern of the primary mirrors.  (Image: NASA)A selfie taken by the Webb Telescope, showing the hexagonal pattern of the primary mirrors. (Image: NASA)

With the dots oriented into a hexagonal formation, the team will now go about Segment Alignment in which large positioning errors will be corrected for each segment. The team will also update the secondary mirror alignment, which will make each dot appear more focused; it’ll basically be like giving each mirror a pair of glasses. The third phase is called Image Stacking, and it’s exactly how it sounds: the team will bring all 18 spots of light on top of each other to form a single dot.

The current orientation of the mirrors should make the second and third steps more manageable. As Lallo explained, once the Image Stacking process gets underway, the “familiar arrangement” of the 18 mirrors will give the team an “intuitive and natural way of visualising changes in the segment spots in the context of the entire primary mirror.” The commissioning team “can now actually watch the primary mirror slowly form into its precise, intended shape,” he added.

The alignment stage began on February 2, and it should be completed by the end of the month. Launched on Christmas Day 2021, Webb is expected to enter into the science phase of the mission in June, at which time it will explore some of the most distant regions of the universe, the evolution of galaxies over time, and the atmospheres of extrasolar planets, among other celestial phenomena.