[HN Gopher] Ask HN: Why can't Webb take (suboptimal) photos as s...
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       Ask HN: Why can't Webb take (suboptimal) photos as soon as it gets
       to L2?
        
       I don't understand why there's a five month wait after getting to
       L2. Why not release some suboptimal photos until then?
        
       Author : amichail
       Score  : 8 points
       Date   : 2022-01-10 22:14 UTC (47 minutes ago)
        
       | MisterBiggs wrote:
       | A large part of the wait is for the telescope to cool down, many
       | of the instruments are likely to not function at all until they
       | reach extremely cold temperatures. The other issue is that the
       | complexity of the instruments means that without rigorous
       | calibration any data gathered is likely to be completely useless
       | noise. The calibration isn't as simple as turning a blurry image
       | into a clear one.
       | 
       | Here's a whole list of calibration challenges that needs to be
       | overcome: https://www.stsci.edu/~INS/2010CalWorkshop/mather.pdf
        
       | dondt21 wrote:
       | The individuals mirrors need to be adjust and that can take
       | months
        
       | geoah wrote:
       | > It will take the JWST team three months to very slowly and
       | carefully align the 18 mirror segments. How slow? One of the
       | telescope scientists described it to me this way: "the mirror
       | segments move at the same rate that a blade of grass grows." This
       | delicate but time-consuming process brings the 18 separate images
       | together to create one sharp image.
       | 
       | > The first round of focusing will be for just one instrument,
       | the Near-Infrared Camera. Remember, though, that JWST has four
       | separate instruments (more on that below), and they are not all
       | looking at exactly the same point on the sky. The focusing
       | process must then be repeated in what is called a "Multi-
       | Instrument Multi-Field" (MIMF) sequence, which may be done more
       | than once to achieve perfect focus for all the instruments.
       | 
       | > By the time JWST is four months out from launch, the telescope
       | should be aligned, and all the instruments focused. After that,
       | the JWST team turns its attention to the science instruments
       | themselves.
       | 
       | From https://www.planetary.org/articles/jwst-first-images
       | 
       | ---
       | 
       | I can only assume (fyi I have no real idea what I'm talking about
       | here) that since JWST is designed to see so far into space that
       | trying to take a picture without aligning any of the instruments
       | and while in transit would result in something more incoherent
       | than just a suboptimal picture.
        
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       (page generated 2022-01-10 23:01 UTC)