NASA Releases Progress Photos of James Webb Mirror Alignment
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Yesterday, NASA released images showing the progress that Webb engineers have made in aligning the telescopes 18 hexagonal mirror segments. There are seven total phases in the mirror alignment process that must be completed over the next few months before James Webb is ready to begin making science observations, and the team has just completed the first three of them.
The first phase of mirror alignment for JWST after instruments onboard detected first light involved determining which mirror segments corresponded with points of light detected by the telescope. Since the mirror segments were all essentially facing different directions, rather than focusing the light into a single point, the first image of a single star appeared to be 18 points of light randomly scattered across the picture. The team then had to determine the mirror segment that each point of light come from so they could begin alignment.
After segment image identification was complete, the team began working on phases two and three, segment alignment and image stacking. Once Webb’s team identified each segment, they began moving each segment until they roughly formed the shape of the telescope. This rough image, known as an image array, was released by NASA last week.
After the image array had been created, JWST’s team made fine adjustments until the blurry initial image became 18 defined points of light. This marked the end of phase two. The team then began image stacking, which involves slowly moving all the segments until they combine into a single image of the star. While the picture appears to show a completed, aligned image, Webb’s mirror segments are still acting as 18 individual telescopes rather than a single big one. This is where the next four phases of mirror alignment come in, and why alignment is set to take several months.
