James Webb telescope launch info

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Re: James Webb telescope launch info

#41  Postby BlackBart » Dec 28, 2021 10:35 am

OK... I'm stressing about whether some origami a million miles away will work... as if I don't have enough stress in my life. :nono:
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Re: James Webb telescope launch info

#42  Postby newolder » Dec 28, 2021 11:01 am

Here's a NASA blog with yesterday's post, "More Than You Wanted to Know About Webb’s Mid-Course Corrections!" Think again, NASA.

Anyhoo, that link includes reports of the various stages in JWST deployment, with more to come, obviously...
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Re: James Webb telescope launch info

#43  Postby i have no avatar » Dec 30, 2021 5:58 am

newolder wrote:Where is Webb? A handy tool to track the mission after the successful launch:
https://jwst.nasa.gov/content/webbLaunc ... sWebb.html


The hot and cold side temperature data is now available at the link site.
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Re: James Webb telescope launch info

#44  Postby aufbahrung » Dec 30, 2021 9:05 am

Something will tear. They combined fragile and robust materials along with the energies/temperatures involved from all directions. My rabbits foot of engineering luck tells me something will break. I've no data, this feeling of doom is based purely on my engineering intuitions.
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Re: James Webb telescope launch info

#45  Postby BlackBart » Dec 30, 2021 9:13 am

Wow. I got to get me some oven gloves made out of that stuff. :awesome:
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Re: James Webb telescope launch info

#46  Postby TopCat » Dec 30, 2021 10:57 am

aufbahrung wrote:Something will tear. They combined fragile and robust materials along with the energies/temperatures involved from all directions.

OMG, wow. I bet you're right, as they probably never thought of that in all the decades of design and planning that went into the mission. :ask:

My rabbits foot of engineering luck tells me something will break. I've no data, this feeling of doom is based purely on my engineering intuitions.

Having read this post, I now have yet another reason (not that I needed any more) to really, really hope that the telescope is a roaring success for the next 10+ years.
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Re: James Webb telescope launch info

#47  Postby BlackBart » Dec 30, 2021 11:55 am

Engineering intuitions. LOL.
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Re: James Webb telescope launch info

#48  Postby hackenslash » Dec 30, 2021 12:23 pm

TopCat wrote:OMG, wow. I bet you're right, as they probably never thought of that in all the decades of design and planning that went into the mission. :ask:


I assumed it was a joke, but they have indeed. The heat shield, which is really the only thing prone to tearing, has been constructed in segments precisely to limit tears, and in such a way that a tear in one layer will have minimal impact overall, as any additional heat is channelled away between the layers.

Not entirely without risk, especially during transit to L2, but not entirely unmitigated either.
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Re: James Webb telescope launch info

#49  Postby newolder » Dec 30, 2021 4:13 pm

i have no avatar wrote:
newolder wrote:Where is Webb? A handy tool to track the mission after the successful launch:
https://jwst.nasa.gov/content/webbLaunc ... sWebb.html


The hot and cold side temperature data is now available at the link site.


Indeed. A graphic for the sensor placements:
Image
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Re: James Webb telescope launch info

#50  Postby TopCat » Dec 30, 2021 7:01 pm

hackenslash wrote:
TopCat wrote:OMG, wow. I bet you're right, as they probably never thought of that in all the decades of design and planning that went into the mission. :ask:


I assumed it was a joke

Well sarcasm, yes :)

To be fair, it's not impossible, of course, that despite decades of planning, they make a stupendous cock-up. Hubble being a case in point. But my Bayesian prior, as Sean Carroll is forever banging on about, on Auf's engineering intuitions, is quite low.

The heat shield, which is really the only thing prone to tearing, has been constructed in segments precisely to limit tears, and in such a way that a tear in one layer will have minimal impact overall, as any additional heat is channelled away between the layers.

But good to know.. :cheers:
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Re: James Webb telescope launch info

#51  Postby newolder » Jan 01, 2022 9:49 am

Both port and starboard shield booms are reported to be in place and now the tension of tensioning the five layers ramps up over the next few days. I was surprised to note the reported temperatures haven't changed much yet and the differentials worry me a bit but this could be thermal inertial or something other and I should keep calm get another brew. Onwards and upwards (to L2) ! ...
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Re: James Webb telescope launch info

#52  Postby i have no avatar » Jan 04, 2022 3:54 am

First three layers of the shield have been fully tightened.

https://blogs.nasa.gov/webb/2022/01/03/ ... tightened/
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Re: James Webb telescope launch info

#53  Postby TopCat » Jan 04, 2022 6:50 pm

All five now, apparently.

https://webb.nasa.gov/content/webbLaunc ... lorer.html

https://www.nasa.gov/press-release/suns ... -telescope

Oh, and 75% of the 344 single points of failure have not failed...

https://twitter.com/NASAWebb/status/147 ... 59553?s=20

344???? WTAF???? :cheers: :cheers:
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Re: James Webb telescope launch info

#54  Postby newolder » Jan 05, 2022 11:14 am

Live coverage of the secondary mirror deployment is due around 1445 UT (9:45 AM ET), depending on schedule timings, at nasa.gov/live and https://www.youtube.com/watch?v=21X5lGlDOfg

Another nerve-shredding session ahead...

ETA Whoop! Another fine job by all concerned!
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Re: James Webb telescope launch info

#55  Postby TopCat » Jan 05, 2022 5:11 pm

Ah good, they got the SMSS locked in place then? Annoyingly I had to miss the last few minutes.
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Re: James Webb telescope launch info

#56  Postby newolder » Jan 07, 2022 2:36 pm

Coverage of the port wing mirror deployment has begun. Tomorrow for the starboard and then individual segment tweaks and cool-down to operating temperatures begins before final insertion into L2 orbit. So, just a few remaining hurdles then...

https://www.youtube.com/watch?v=21X5lGlDOfg



ETA
1611 UT and no coverage yet. Sigh...

ETA
My mistake - Coverage is set to begin TOMORROW for the starboard wing deployment :doh:

Get ready for @NASAWebb's final unfolding!

We'll have live coverage on social media and NASA TV as Webb deploys its second and final primary mirror wing, with our broadcast beginning no earlier than 9am ET (14:00 UTC) Sat., Jan. 8: https://go.nasa.gov/3eZLxRy


ETA Port side completed! Starboard tomorrow...

The process of deploying the port side mirror wing began at approximately 8:36 a.m. EST. At approximately 2:11 p.m. EST, engineers confirmed that the panel was fully secured and locked into place, and the deployment was complete.
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Re: James Webb telescope launch info

#57  Postby newolder » Jan 08, 2022 3:30 pm

Starboard wing deployed. Latching into place... (same link ^ for live coverage)

More congratulations to the teams. Yay!
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Re: James Webb telescope launch info

#58  Postby TopCat » Jan 08, 2022 7:00 pm

And now fully latched:

https://twitter.com/NASAWebb/status/147 ... 60609?s=20

I was watching some of the nasa.tv footage earlier, and they were talking about the mirror manufacture.

They got it roughly machined to shape, then cooled it right down to temperature (33K or something like that), and then measured how it deformed as it cooled. And then sent it away to get it machined again to compensate for the change in shape so that it would be right when it was at operating temperature.

They also had to compensate in the machining for the fact that it was under gravity during manufacture, but wouldn't be while operating.

And the actuators.... don't even get me started on the actuators. 7 per hexagon. With stepping motors that can move the mirror in increments of 1/20,000 of the width of a human hair, I think he said. So as to resolve to about a wavelength in operation.

Unbelievable. And it's all worked perfectly so far. Just amazing.
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Re: James Webb telescope launch info

#59  Postby hackenslash » Jan 08, 2022 7:04 pm

TopCat wrote:They got it roughly machined to shape, then cooled it right down to temperature (33K or something like that), and then measured how it deformed as it cooled.


Lessons learned from Hubble. When they were defining the lens curvature, the gauge they relied on was calibrated for the wrong temperature, which led to the wrong dimensions in the grinding of the lens, which in turn buggered up alignment with the sensor array.

ETA: Meant to say, I came across a decent doco the other day made by Discovery entitled 'Beyond Hubble'. It's one of those breathless pop-sci jobbies, but quite approachable and a decent explanation of the design decisions and tech behind the mirror asembly, etc.
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Re: James Webb telescope launch info

#60  Postby Macdoc » Jan 09, 2022 10:40 am

The change in technology over the 30 years this was in development was astonishing and I guess at this point perhaps the delays and overruns can be considered worthwhile. :cheers:
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