Author Topic: JWSTelescope  (Read 2512 times)

Beardy

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Re: JWSTelescope
« Reply #50 on: 03 January, 2022, 09:15:53 pm »
Apropos to the above; I was recent;h looking at a British canal route finder on the interwebs and all the distances were giving in miles and furlongs. I had heard that the canals were a bastion of gammons, but the more research I do into thE possibility of obtaining g a live aboard the less I feel like doing so because my potential neighbours are going to be racing ranting gibbonous gammons.
Sorting my life out, one shed at a time.

Cudzoziemiec

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Re: JWSTelescope
« Reply #51 on: 03 January, 2022, 09:23:45 pm »
Might it be that canals were originally built in miles and furlongs and have never really been surveyed since? Just as railways still use miles and chains cos that's what the Victorian engineers used and the cost of resurveying (simply converting would introduce all sorts of errors) isn't worth it? Similar rules apply to cricket, horse racing and whatever...
Riding a bike through a city is like navigating the collective neural pathways of a vast global mind.

Re: JWSTelescope
« Reply #52 on: 03 January, 2022, 09:33:15 pm »
Apropos to the above; I was recent;h looking at a British canal route finder on the interwebs and all the distances were giving in miles and furlongs. I had heard that the canals were a bastion of gammons, but the more research I do into thE possibility of obtaining g a live aboard the less I feel like doing so because my potential neighbours are going to be racing ranting gibbonous gammons.

The reason for that is because all the bridge and tunnel markings will be in chains, furlongs and miles. Just historical, no gammon conspiracy.

There are a fair number of bigoted old gits to be found on the waterways, but also a lot of hippy types and lots of other sorts too. Don't be put off by the minority that post loudly on canal forums. If you want to discuss practicalities start a new thread - I'm moving on to my new boat tomorrow after a gap of over 20 years.
Quote from: tiermat
that's not science, it's semantics.

Kim

  • Timelord
Re: JWST
« Reply #53 on: 03 January, 2022, 09:43:41 pm »
TI actually L: I was wondering whether it was getting a bit crowded at the L2 "point" and how big a point it actually is, but it turns out that the various telescopes do not just orbit the sun but also orbit the L2 point. How they orbit something that's not actually there and so doesn't have any gravity is some kind of magic to do with gravitational wells or something.

They're only not there in the sense that a hilltop isn't there:  Think of gravity like a contour map, with the Earth and Sun as holes of appropriate depth.  L1, L2 and L3 are 'saddles'[1], and L4 and L5 are ridges.  If you place an object near L1, L2 or L3 it will tend to drift away, but if you put it in orbit around the point, you can keep it there with the occasional burst of thrust.  That's why the JWST's lifetime is limited by its fuel supply; eventually it will run out and go wandering off into heliocentric orbit.

You'd expect the same to be true of L4 and L5, but it turns out the contour map is rotating (I dunno, it's in the hands of a car passenger who's a frequent perpetrator of terms like "other left" or something), and inertia pulls it back into place.




[1] In the horse rather than bicycle sense.

Re: JWSTelescope
« Reply #54 on: 04 January, 2022, 05:55:11 pm »
Huzzah !! Sunshield deployment complete.

I would think that the engineers were more concerned about this stage than any of the others.
Rust never sleeps

Re: JWST
« Reply #55 on: 04 January, 2022, 09:02:35 pm »
I bet the sensors are reading in Celsius/Kelvin and it's being converted from degrees SCIENCE to degrees Frankenstein and back.

TIL: according to that website, the opposite of "Metric" is "English"  :facepalm:

TI actually L: I was wondering whether it was getting a bit crowded at the L2 "point" and how big a point it actually is, but it turns out that the various telescopes do not just orbit the sun but also orbit the L2 point. How they orbit something that's not actually there and so doesn't have any gravity is some kind of magic to do with gravitational wells or something.
Need to allow space for the alien monolith/stargate, too.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Kim

  • Timelord
Re: JWSTelescope
« Reply #56 on: 05 January, 2022, 06:12:11 pm »
Secondary mirror appears to have deployed successfully.   :thumbsup:

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: JWSTelescope
« Reply #57 on: 05 January, 2022, 06:22:36 pm »
Huzzah!

Although not previously posting here i am quietly excited about this, if only from a difficulty pov
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: JWSTelescope
« Reply #58 on: 05 January, 2022, 06:32:30 pm »
Indeed. Great news. Though I have to question this blurb on the update website : -

Quote
The secondary mirror plays an important role in reflecting the light from the primary mirror to where the instruments sit, behind the primary mirror.

An important role ??  It's the only thing doing the reflecting.
Rust never sleeps

Re: JWSTelescope
« Reply #59 on: 05 January, 2022, 06:43:28 pm »
And here's a thought. If the side bits of the main mirror fail to deploy then they have at least got two thirds of the main mirror in place, so, barring other possible disasters, they are guaranteed to have a working telescope.
Rust never sleeps

Jaded

  • The Codfather
  • Formerly known as Jaded
Re: JWSTelescope
« Reply #60 on: 05 January, 2022, 07:28:28 pm »
Indeed. Great news. Though I have to question this blurb on the update website : -

Quote
The secondary mirror plays an important role in reflecting the light from the primary mirror to where the instruments sit, behind the primary mirror.

An important role ??  It's the only thing doing the reflecting.

Let's have a think about that.
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yorkie

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Re: JWSTelescope
« Reply #61 on: 06 January, 2022, 03:29:21 pm »
Born to ride my bike, forced to work! ;)

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Re: JWST
« Reply #62 on: 08 January, 2022, 07:34:15 pm »
JWST status page:

https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html


For sensible units: https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?units=metric

...with improbable accuracies  ::-)

I bet the sensors are reading in Celsius/Kelvin and it's being converted from degrees SCIENCE to degrees Frankenstein and back.

Probably mV, mA or something like that.

It just bugged me that the temperatures were quoted in integer degF (but to two DP  ::-)) then converted to degC with the same 2DP.

They have now changed both Celsius and arcane to the nearest whole number. They also admit that the temperatures are only updated daily, as they don't expect fast changes.
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Pingu

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woollypigs

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Re: JWSTelescope
« Reply #64 on: 08 January, 2022, 09:46:55 pm »
\o/ for space origami
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Giraffe

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Re: JWSTelescope
« Reply #65 on: 09 January, 2022, 08:42:50 am »
Now, if it hadn't all unfurled:
'Oh what a tangled Webb we wove'
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