James Webb Space Telescope

Discussion in 'Astronomy, Exobiology, & Cosmology' started by geordief, Dec 24, 2021.

  1. foghorn Valued Senior Member

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  3. geordief Valued Senior Member

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    Last edited: Jan 26, 2022
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  5. sculptor Valued Senior Member

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    I find it amazing that way out in space, with no atmosphere: The hot side of the heat shield is 130 degrees F.

    Is that accurate?
     
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  7. James R Just this guy, you know? Staff Member

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  8. James R Just this guy, you know? Staff Member

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    Yes. Photons from the Sun that aren't reflected from the telescope can only be absorbed, and their energy has to go somewhere; it heats the telescope.

    The lack of an atmosphere means that the only way the telescope can lose heat is to radiate it away (as lower-energy photons). That process is far slower than the conduction/convection processes that happen in air.

    The 5-layer heat shield is supposed to capture the light from the sun and radiate it away, including by reflecting light emitted from each layer back and forth and channelling it down the layers and out into space, away from the telescope's mirrors and instruments.

    Once the telescope reaches equilibrium it will be radiating solar energy at the same rate that it receives it, which means the temperatures on the front and back of the shields will be approximately stable.
     
  9. billvon Valued Senior Member

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    Yep. No atmosphere to conduct away the heat. It would get conducted (and radiated away) on the other side - but the designers were very careful to add a LOT of insulation to prevent that.
     
  10. foghorn Valued Senior Member

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    Sorry if I'm misunderstanding you again, but do you mean this:

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    https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
     
  11. geordief Valued Senior Member

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  12. geordief Valued Senior Member

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    Now it is c=-352F
    d=-344F

    So it seems c and d have gone down by 4 and 11 degrees Fahrenheit respectively over the last 6 days.
     
  13. DaveC426913 Valued Senior Member

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    Bomb cyclone.
     
  14. geordief Valued Senior Member

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    Well it's just as much fun as the daily Covid statistics.

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  15. geordief Valued Senior Member

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  16. geordief Valued Senior Member

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    "The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam," said Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy at University of Arizona, in a statement."
     
  17. psikeyhackr Live Long and Suffer Valued Senior Member

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  18. Write4U Valued Senior Member

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    This may be of interest as to the various tasks the Webb telescope can perform.

     
  19. geordief Valued Senior Member

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  20. DaveC426913 Valued Senior Member

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    Ah. Answered before I had a chance to ask:
     
  21. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    According to the text this would be the 3rd interloper from another star system dicovered and the first by the James Webb Telescope

    Well done all those people involved

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    I spy with my big eye something beginning with interloper

    I spy with my little eye - Dueling Banjos with a violin getting into the action

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    Last edited: Mar 25, 2022
  22. geordief Valued Senior Member

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    Don't think Webb has started work yet,has it?

    Can't have discovered anything,surely?
     
  23. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Still in the process of focusing the mirror, without going back to check think about another 6 weeks to go

    But yes it has checked the focus already on a star and apparently found this inter star system interloper

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    Last edited: Mar 25, 2022

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