The James Webb Telescope

For all chat about the things in the sky without a central nervous system
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RoGeorge
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The James Webb Telescope

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Last time I've read about this 10 billion telescope, it was to be launched this month, on 24th of December 2021.

I hope the launching trajectory was calculated such that it won't hit Santa. :D
Last edited by RoGeorge on Tue Mar 01, 2022 10:52 am, edited 2 times in total.
Tony0945
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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Santa is a Commie! He wears a red suit and gives free stuff to people that don't for it! /snark
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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#controlgroup
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RoGeorge
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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Tony0945 wrote: Sun Dec 19, 2021 7:27 pm Santa is a Commie!
Santa is anagram for Satan!
:mrgreen:
...71...
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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RoGeorge wrote: Sat Dec 25, 2021 4:41 pm
Tony0945 wrote: Sun Dec 19, 2021 7:27 pm Santa is a Commie!
Santa is anagram for Satan!
:mrgreen:
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RoGeorge
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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JWST's mirror actuators are AMAZING!
Breaking Taps




Yeah well! I'm gonna go build my own telescope...

:D
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RoGeorge
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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https://www.eevblog.com/forum/chat/james-webb-space-telescope-cooling-its-jets/msg4023442/#msg4023442 wrote:
Current status: https://jwst.nasa.gov/content/webbLaunc ... its=metric

The temperature in French Guiana (launch site) is virtually all year around the value of 30°C 303°K 86°F
If Webb was not cooled on the pad then when the fairings exposed Webb to space, the Instrument Radiator would radiate 468W/m²

Now almost two months later it has cooled to 43°K -231°C and radiates 172mW/m²
Dropping another 6.68° photon radiation will drop by 50% This is why it will take months to cool.
At 20°K it will radiate 9mW/m²

Instrument Radiator Temp(K) 42
Space Temp (K) 4
Area m² 1
Emissivity 0.98
Stefan Boltzmann constant 5.6702E-08
Watts of Photon radiation 0.17289

Emissivity*Stefan Boltzmann constant*Area m²*((Instrument Radiator Temp (K)E4)-(Space Temp (K)E4))

The mirrors are gold and almost do not radiate, emissivity 0.02, they cool from the back non-gold side.
Radiators become thousands of times less effective in outer space.
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Henry Crunn
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Re: URGENT: Somebody please notify Santa about the James Webb Telescope!

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Well radiation is about all there is in space.

The alternatives convection and conduction, don't work very well.
Convection requires gravity and a fluid. Conduction ... but to where?

I suppose Webb could use a heat pump of sorts, bet that generates heat and may have moving parts.
Better to just wait.
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You can't get the 'shiver me timbers' wood' you know.
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RoGeorge
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Re: The James Webb Telescope

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When your dad is a metrologist working at the James Webb telecope. :D
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Re: The James Webb Telescope

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A Briefly Famous Star (and calibrating the JWST) - Sixty Symbols
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Re: The James Webb Telescope

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What does the James Webb Use to See the Universe?
Curious Droid
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