James Webb Telescope Launch (finally)

@eg2505 , my own question about these issues weeks ago was why they couldn't first do all the deployments in Earth orbit before moving on.

The answer seemed to be that an extra booster to continue the trip later would have added a lot to the cost and that they must have been confident enough to risk it, but that was mostly our interest groups' educated guesses AFAIK.
 
Brian_G said:
@eg2505 , my own question about these issues weeks ago was why they couldn't first do all the deployments in Earth orbit before moving on.

The answer seemed to be that an extra booster to continue the trip later would have added a lot to the cost and that they must have been confident enough to risk it, but that was mostly our interest groups' educated guesses AFAIK.
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thats also a good question, I thought at 10 Billion USD, being cheap and having it deploy on the move is risky, should something go hilariously wrong.
what is their backup plan? steer it back to Earth? work with degraded systems? or does the option to re-flash and send an entire new Operating system actually exist.

also, do they have a backup Telescope down on Earth? a flight spare should the need present itself? maybe without the Gold plated Mirror, but identical in every single way, that could be flight readied in a short time.
or was that never a consideration?
 
eg2505 said:
what is their backup plan? steer it back to Earth? work with degraded systems? or does the option to re-flash and send an entire new Operating system actually exist.
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Only one that's been mentioned by them, but they really are past most serious failure risks.

eg2505 said:
also, do they have a backup Telescope down on Earth?
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Nothing that could come close

eg2505 said:
a flight spare should the need present itself? maybe without the Gold plated Mirror, but identical in every single way, that could be flight readied in a short time.
or was that never a consideration?
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Never considered, not economically etc. practical.


It is what it is.
 
Brian_G said:
Nothing that could come close
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so there is a Dummy one down on Earth? or they never built it, they just assumed its gonna work with the amount of cash they paid for it.
even the Mars Rovers have Twins down on Earth, that could conceivably be flight readied and sent out should something catastrophic happen.

Like a Rocket blowing up or a comma in the code somewhere crashes the entire system.
 
eg2505 said:
so there is a Dummy one down on Earth?
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They have some sort of models. The massive complexity makes other considerations impractical, but I can't tell you more - maybe read more of their FAQs.
Bottom line is they got through the main risk period.
 
Brian_G said:
Bottom line is they got through the main risk period.
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Outer space is a dangerous place, what if a micrometeroid crashes into a vital system?
or they finally turn on this Billion Dollar science experiment and it never works properly, due to some issue they never saw coming.

I mean what is their plan B? do they even have one?
 
eg2505 said:
I mean what is their plan B? do they even have one?
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Okay I've got time now so let's kick this ball around a bit more..

Let's say you're going from SA to New Zealand.
You know there's a disproportionately small chance that your plane could crash, but you can't take any precautions... so what do you do?

You go.

And don't say you'll rather take a ship, they give you covid / smash into things / sink.
 
eg2505 said:
Outer space is a dangerous place, what if a micrometeroid crashes into a vital system?
or they finally turn on this Billion Dollar science experiment and it never works properly, due to some issue they never saw coming.

I mean what is their plan B? do they even have one?
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What would be your suggestion for a plan B given where the telescope is going to reside?
 
Redundancy for all systems just isn't possible at the cost...

https://www.space.com/james-webb-space-telescope-deployment-points-of-failure

344 points of failure​


"There are 344 single-point-of-failure items on average," Menzel said about the Webb mission, adding that "approximately 80% of those are associated with the deployment … It's hard to avoid when you have a release mechanism. It's hard to put full redundancy into that."

Webb has 144 release mechanisms "which all must work perfectly," Krystal Puga, Webb spacecraft systems engineer for Northrop Grumman, which built the spacecraft, said during the briefing.

"Like an origami object, proper folding and unfolding is necessary in order to achieve a specific shape," Alphonso Steward, Webb deployment systems lead for NASA Goddard, said during the briefing.
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That's why it was tested for so long and why the launch was delayed multiple times, they had to make sure that things just worked..
 
Brian_G said:
Okay I've got time now so let's kick this ball around a bit more..

Let's say you're going from SA to New Zealand.
You know there's a disproportionately small chance that your plane could crash, but you can't take any precautions... so what do you do?

You go.

And don't say you'll rather take a ship, they give you covid / smash into things / sink.
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this isnt NZ where there are options, this is in the most Hostile, Cold, Dangerous place imaginable,
where anything that can go wrong, however small, could result in a Gigantic piece of space junk.

yes, you can do everything imaginable to mitigate it, but at some point even the best laid plans can/do go wrong,
what I want to know are what are their contingencies? what can they do?

or is all of that classified? or not shared with the rest of the public.
 
eg2505 said:
this isnt NZ where there are options...
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Again, what options?

eg2505 said:
yes, you can do everything imaginable to mitigate it, but at some point even the best laid plans can/do go wrong,
what I want to know are what are their contingencies? what can they do?

or is all of that classified? or not shared with the rest of the public.
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We've answered as best we can. They either make it or they fail, and a lot of science behind this so not sure why you think it hasn't been thought through as best as possible all these decades it's been in preparation.

But @Cray 's post above probably sums it up best, I'll leave it there.
 
Brian_G said:
Again, what options?


We've answered as best we can. They either make it or they fail, and a lot of science behind this so not sure why you think it hasn't been thought through as best as possible all these decades it's been in preparation.

But @Cray 's post above probably sums it up best, I'll leave it there.
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on Earth there are plenty of options, not always feasible ones, but there are always options

but out in the cosmos, if something goes wrong, what can/will they do, just seems to me a lot riding on a few systems that could fail and never work right.
big gamble.
 
Brian_G said:
Again, what options?


We've answered as best we can. They either make it or they fail, and a lot of science behind this so not sure why you think it hasn't been thought through as best as possible all these decades it's been in preparation.

But @Cray 's post above probably sums it up best, I'll leave it there.
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on Earth there are plenty of options, not always feasible ones, but there are always options

but out in the cosmos, if something goes wrong, what can/will they do, just seems to me a lot riding on a few systems that could fail and never work right.
big gamble, but happy it all worked out in the end,
 
eg2505 said:
on Earth there are plenty of options, not always feasible ones, but there are always options
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So could jump out near-supersonic ultra high airplane, pity it isn't feasible. Yeah, okay.. :notworthy:

Why am I back? To discuss scientists and their work, something you don't seem to believe in even though literally thousands of them have been involved along with plenty of engineers and all sorts of official bodies of note.

Now with covid I can understand, the science was hijacked early on by politicians. But why such deep mistrust of expert effort in this well established line of discipline and success?
 
Brian_G said:
So could jump out near-supersonic ultra high airplane, pity it isn't feasible. Yeah, okay.. :notworthy:

Why am I back? To discuss scientists and their work, something you don't seem to believe in even though literally thousands of them have been involved along with plenty of engineers and all sorts of official bodies of note.

Now with covid I can understand, the science was hijacked early on by politicians. But why such deep mistrust of expert effort in this well established line of discipline and success?
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why such a mistrust, because things, can and do happen especially when so many things all have to work in harmony,
your sending a finely crafted spacecraft into the great unknown, sure you've designed X,Y and Z for it to survive, but something can still crop up nobody foresaw.

all I want to know is if something goes wrong, what can they do?
only software fixes from this point forward, and nothing else? so if a Micrometeorite smashes into the mirror, and renders the entire thing worthless?

what then? whats the backup plan?
 
eg2505 said:
why such a mistrust, because things, can and do happen especially when so many things all have to work in harmony,
your sending a finely crafted spacecraft into the great unknown, sure you've designed X,Y and Z for it to survive, but something can still crop up nobody foresaw.

all I want to know is if something goes wrong, what can they do?
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Okay, I get you now.
Bottom line is mostly about money.

eg2505 said:
only software fixes from this point forward, and nothing else? so if a Micrometeorite smashes into the mirror, and renders the entire thing worthless?

what then? whats the backup plan?
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There are plans for that if only partial damage as it so happens - single pieces of the mirror can be disabled, some of it surprisingly done by software changes.

Another example - if (or rather when) the sunshield is punctured, they've built in a kind of ridge throughout that stops it from tearing too far.

They've put in lots of effort, one thing on their side in the end was time. But it's a lot to read - if you want to I can give you a link to their massive press release "book".
 
Brian_G said:
@eg2505 , my own question about these issues weeks ago was why they couldn't first do all the deployments in Earth orbit before moving on.

The answer seemed to be that an extra booster to continue the trip later would have added a lot to the cost and that they must have been confident enough to risk it, but that was mostly our interest groups' educated guesses AFAIK.
Click to expand...

There are numerous practical difficulties with deployment in earth orbit, and no plausible benefits. If you over-boost the telescope with the shade unfurled, it could buckle. Also heat radiation from the earth could damage sensitive instruments.
 
eg2505 said:
so there is a Dummy one down on Earth? or they never built it, they just assumed its gonna work with the amount of cash they paid for it.
even the Mars Rovers have Twins down on Earth, that could conceivably be flight readied and sent out should something catastrophic happen.

Like a Rocket blowing up or a comma in the code somewhere crashes the entire system.
Click to expand...

Yeah, lets spend 10 billion dollars on a stand-by that might not be needed.....

Have you not read how long and how complex building just one was?
 
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