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James Webb Space Telescope (JWST)

Discussion in 'SpaceX' started by Grendal, Sep 28, 2017.

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  1. Grendal

    Grendal Active Member

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    More general space oriented rather than anything SpaceX. Delayed until 2019.

    JWST launch slips to 2019 - SpaceNews.com

    To bring this back to SpaceX, the new BFR could launch something even bigger than JWST very easily.
     
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  2. swaltner

    swaltner Member

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    Bummer on the delay. I'm anxious to see what mysteries can be uncovered once the JWST sees first light.
     
  3. jkn

    jkn Member

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    I want to see those pictures also. But I don't like design. It is very complex automatically unfolding origami. Mirror part has to get into place with accuracy better than wavelength of light. It is non serviceable, so it must be perfect. I think there is a limit how complex unserviceable mechanism should be.

    I read interesting discussion and I agree with author Dick Eagleson:
    evp (thank you) posted a link: The Space Review: SpaceX prepares to eat its young

    From article and discussion:
    "The next major space telescope after the James Webb Space Telescope, for example, might cost as little as two to five percent of the Webb's $9 billion budget. This could also allow it to have a sizable family of siblings. BFR can put things almost 9 meters across and massing up to 150 tonnes into LEO. Refueling allows such a payload to be dispatched from LEO to pretty much anywhere. The Steward Mirror Lab at the University of Arizona has been making one-piece, 18-ton (16.4 tonne) 8.4-meter telescope mirrors for two decades. Each one costs in the low tens of millions of dollars. I’m sure the folks at Steward could make some consortium of academic institutions, foundations, and philanthropists who like their names on things a nice quantity discount deal on enough mirrors to pepper the whole solar system with instruments each having over a dozen times the light-gathering power of Hubble. Need I say more?"


    "Two to five percent of JWST's $9 billion sunk cost is $180 million to $450 million. Structure, optics and instruments for large space-based and terrestrial telescopes are expensive, but they don't have to be JWST-style expensive. "


    James Webb Space Telescope - Wikipedia
    "With the combined U.S. and international funding, the overall cost not including extended operations is projected to be over $10 billion when completed"

    That's before latest delay.


    "It is more complicated and expensive to build a folding mirror than a fixed one and it is more expensive to build a segmented mirror than a unitary one. That said, the mirror was, indeed, not the source of most of JWST's preposterous overruns. One rather considerable source of delays and cost, as I understand it, was the refrigeration unit needed to keep the focal plane array cooled to ca. 3 K. A lot of that problem, in turn, was driven by the limited amount of mass budget available for radiators."

    "Beryllium mirrors were also a response to limited mass budget. They are not mandatory for IR astronomy - JWST's specialty. Aluminized glass also works. But beryllium is very strong and rigid in thin sections. To get comparable stiffness with glass would require much more mass. BFR has so much throw weight, though, that one could straightforwardly take a glass mirror, originally designed for terrestrial telescopes, and just build a space telescope around it. "

    Then some discussion about beryllium being poisonous. Which didn't lower costs.
     
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