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Webb flies Ariane 5: watch the launch live on 25 December

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Re: Webb flies Ariane 5: watch the launch live on 25 December

#121

Post by akiselev »

GekkePrutser wrote: post #116
throw0101a wrote: post #60

Earlier quoted context omitted.

> Is JWST as brittle as the news want to make us think? Or are there technical reasons or acceptable failure modes that gives confidence that those steps are not as critical as the news let us people know? There is no room for redundancy in many aspects of the design, unlike, say a Boeing 777 or Airbus A350. How can you have a redundant heat shield, or primary mirror (two parts of which swing)? I'm sure some computer…

Does this have a heat shield? It won't re-enter right? It's far too far away for that.

It's actually a sunshield [1]

[1] https://webb.nasa.gov/content/observatory/sunshield.html

Re: Webb flies Ariane 5: watch the launch live on 25 December

#123

Post by [deleted] »

soperj wrote: post #96
rrss wrote: post #44

Earlier quoted context omitted.

How about planning around the single most celebrated holiday in the US, religious or not: https://en.m.wikipedia.org/wiki/Public_holidays_in_the_Unite...

If you worked on something since 1996, do you think you would give two flying figs what day it launches on?

[deleted]

Re: Webb flies Ariane 5: watch the launch live on 25 December

#124

Post by Teknoman117 »

mastax wrote: post #108
throw0101a wrote: post #60

Earlier quoted context omitted.

> Is JWST as brittle as the news want to make us think? Or are there technical reasons or acceptable failure modes that gives confidence that those steps are not as critical as the news let us people know? There is no room for redundancy in many aspects of the design, unlike, say a Boeing 777 or Airbus A350. How can you have a redundant heat shield, or primary mirror (two parts of which swing)? I'm sure some computer…

Better helicopter example is the Jesus Nut.

"Because it it comes off that’s who you’re seeing next"

Re: Webb flies Ariane 5: watch the launch live on 25 December

#125

Post by gfodor »

daenney wrote: post #27
gfodor wrote: post #22

Interesting they found a way to add a hidden risk variable to the launch, by sending it up on a day people are having to choose to not be with their families. Have a bad feeling about this :/

“They” didn’t find anything. It wasn’t originally planned for tomorrow. The weather found a way. There’s only so much wiggle room and launch windows.

I didn’t imply they did it on purpose. The they here is in the spirit of Murphy’s Law. Seriously: launching on Christmas seems like a bad and unnecessary source of entropy.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#126

Post by dimtion »

jcims wrote: post #63
dimtion wrote: post #42

I do have a question about JWST that I wasn't able to find a fine answer in other forums. A lot of people and engineers are saying that the JWST is a marvel of engineering, with truly inovative technical solutions and a giant step up compared to Hubble Telescope. And it does seems like so! However, I'm always baffled how everyone seems proud that the telescope has something like 200 SPOF during deployment, and if eve…

I think this is your earnest attempt at it but its a good place to apply the story from yesterday 'be curious, not judgemental'.

I'd like to apologize if this sounded judgmental. English is not my main language, and perhaps my phrasing sounded like I assumed my domain specific opinion is better than the actual people working on the the project.

Reading the other comments, and maybe to contextualize to my question better, I'm more surprised by how the project is presented as marvelous to the public, rather than thinking that any technical part were overlooked.

While I'm sure that engineering teams at NASA and ESA have countless contingency plans, procedures and failure models. Medias around the project seem to focus on how fragile the deployment procedure is. Great engineering is an act of finding the best balance between opposing constrains, by building technically sound systems but also more importantly designing robust human or automated procedures.

In this story, in my opinion, the media presents a skewed explanation of why the project is incredible by highlighting that it would be incredible that such a brittle deployment procedure would even work.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#127

Post by rrss »

soperj wrote: post #96
rrss wrote: post #44

Earlier quoted context omitted.

How about planning around the single most celebrated holiday in the US, religious or not: https://en.m.wikipedia.org/wiki/Public_holidays_in_the_Unite...

If you worked on something since 1996, do you think you would give two flying figs what day it launches on?

my personal preference is irrelevant. my comment was regarding whether it is tractable to plan around Christmas, or unreasonable because there are too many holidays of comparable significance.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#128

Post by gfodor »

myself248 wrote: post #113
rrss wrote: post #51

Earlier quoted context omitted.

They did though. It was delayed, they chose to delay it from October to December 18 to December 22 to Christmas instead of like the first week of January or whatever. It’s not like this thing is launching to Mars and they’d have to wait a couple years if they miss this week - it could launch on 210 days of each year. https://jwst.nasa.gov/content/about/faqs/faq.html#launchWind... I don’t mind at all, I just think it’…

what's funny about it? You think there's anyone working on this project who isn't super excited to see it go up on Christmas? No better gift than a successful launch. The folks working on preparations overnight surely see themselves as Santa's Elves in some fashion.

Exactly - you highlight the problem. Launching on Christmas introduces unique situational entropy. They should do it later.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#129

Post by kaashif »

ultramegachurch wrote: post #111
BurningFrog wrote: post #105

Earlier quoted context omitted.

We had the capability in 1993, and could of course develop it again. A broken JWT could wait a few years in orbit.

That may be true, but designing a mission based off that hypothetical is a bad idea. The reality is we currently don’t have the capability for humans to service satellites, and developing that capability would probably take years and cost >$100 million. And NASA can’t just decide to take on that endeavor, it would require congress and months of political bickering. JWST was designed for what is currently feasible and…

> developing that capability would probably take years and cost >$100 million. And NASA can’t just decide to take on that endeavor

So what you're saying is, this could easily be funded by some billionaire, e.g. Jeff Bezos who already sells billions of dollars in Amazon stock per year to fund Blue Origin?

Not saying this should be done privately, but if funding is the problem, that problem can be solved.

Space travel is less expensive than most people think, it just isn't very high up on our list of priorities.

Re: Webb flies Ariane 5: watch the launch live on 25 December

#130

Post by yk »

dimtion wrote: post #42

I do have a question about JWST that I wasn't able to find a fine answer in other forums. A lot of people and engineers are saying that the JWST is a marvel of engineering, with truly inovative technical solutions and a giant step up compared to Hubble Telescope. And it does seems like so! However, I'm always baffled how everyone seems proud that the telescope has something like 200 SPOF during deployment, and if eve…

I hope it's just badly thought through marketing. There is currently a AWS spot during nfl games, that shows a spectacular catch and then proclaims that the catch probability is only 3.6% or something. You are meant to be somehow impressed by the unlikelihood I believe, but that their model thought the catch is unlikely and the guy caught it implies a rejection of their model with p=3.6% The JWST marketing seems to work under a similar premise, they proudly proclaim that they couldn't mitigate hundreds of single points of failure, and you're supposed the be impressed by how difficult their task is. Hopefully the engineering did a reasonable job and the marketing is just playing up the wrong thing.
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