[ExI] Webb Space Telescope Mirror Alignment Continues Successfully

BillK pharos at gmail.com
Mon Feb 28 09:30:05 UTC 2022

By NASA February 27, 2022

Webb continues on its path to becoming a focused observatory. The team
has successfully worked through the second and third out of seven
total phases of mirror alignment. With the completion of these phases,
called Segment Alignment and Image Stacking, the team will now begin
making smaller adjustments to the positions of Webb’s mirrors.


Although Image Stacking put all the light from a star in one place on
NIRCam’s detector, the mirror segments are still acting as 18 small
telescopes rather than one big one. The segments now need to be lined
up to each other with an accuracy smaller than the wavelength of the

The team is now starting the fourth phase of mirror alignment, known
as Coarse Phasing, where NIRCam is used to capture light spectra from
20 separate pairings of mirror segments. This helps the team identify
and correct vertical displacement between the mirror segments, or
small differences in their heights. This will make the single dot of
starlight progressively sharper and more focused in the coming weeks.

So far, everything seems to be working as expected!   :)


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