View Poll Results: Will the James Webb Space Telescope successfully deploy?
|
Yes, first time.
|
|
99 |
88.39% |
Nope, and too far away to fix.
|
|
2 |
1.79% |
Not the first time, but we'll figure out a way to get to L2 for a fix
|
|
11 |
9.82% |
|
|
Poll: Will James Webb Telescope successfully deploy?
12-28-2021, 10:16 AM
|
#1
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Jun 2006
Location: Boise
Posts: 7,882
|
Poll: Will James Webb Telescope successfully deploy?
I read yesterday that there are 344 single points of failure. While I'd like to see it succeed, based on that one fact I'm guessing it won't.
__________________
"At times the world can seem an unfriendly and sinister place, but believe us when we say there is much more good in it than bad. All you have to do is look hard enough, and what might seem to be a series of unfortunate events, may in fact be the first steps of a journey." Violet Baudelaire.
|
|
|
|
Join the #1 Early Retirement and Financial Independence Forum Today - It's Totally Free!
Are you planning to be financially independent as early as possible so you can live life on your own terms? Discuss successful investing strategies, asset allocation models, tax strategies and other related topics in our online forum community. Our members range from young folks just starting their journey to financial independence, military retirees and even multimillionaires. No matter where you fit in you'll find that Early-Retirement.org is a great community to join. Best of all it's totally FREE!
You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with our members, see fewer ads, upload photographs, create a retirement blog, send private messages and so much, much more!
|
12-28-2021, 10:31 AM
|
#2
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Mar 2017
Location: City
Posts: 10,351
|
I used to be peripherally in the spacecraft business, with JPL and NASA as customers for circuit chips. Spacecraft reliability calculations are incredibly complex. There are literally thousands and thousands of single point failure vulnerabilities ranging from individual wire connections to the mechanical actuators that cause physical things to happen. In many cases their failure rates are well understood, possibly from actual on-orbit histories. In many others, the failure rates are projected from extensive testing that simulates the physical conditions that they will see from pre-launch transport at 1G, to launch G-force and vibration conditions, to operation on-orbit. The bottom line for any bird is that the reliability predictions have been judged to justify a launch. And the predictions are complex, as some failures would jeopardize the mission, while others might simply prevent some kind of function from being done.
Short answer: "344" is a public-relations number, and the bird is more likely to work than not. Further, your affiant sayeth naught.
__________________
Ignoramus et ignorabimus
|
|
|
12-28-2021, 10:32 AM
|
#3
|
Thinks s/he gets paid by the post
Join Date: Jan 2012
Posts: 2,593
|
I read recently that construction of the JWST was essentially completed by late 2016, and they spent the next several years testing it (and fixing any problems). It suspect that in the five years prior to launch they managed to find and fix everything that could reasonably go wrong.
If anything does happen to fail, however, it won't get fixed. There is no way a manned mission could be developed and sent to the L2 point within the planned lifetime of the telescope. The L2 point is nearly 1,000,000 miles from Earth! That's four times farther than the moon. IMHO, the third poll option is a nonstarter.
|
|
|
12-28-2021, 10:41 AM
|
#4
|
Thinks s/he gets paid by the post
Join Date: Mar 2012
Posts: 3,931
|
You have to put a little faith in our technology. I mean, seriously, who would have ever thought we could send rovers to Mars that would survive for a year or more, and be autonomous for the most part. And then how about sending a drone helicopter along with it, and actually flying it in the Mars atmosphere...and sending high res color photos back to us 220 million miles away! There had to be at least as many single points of failure with those Mars missions. Performance of these things has far exceeded what NASA had hoped to get out of them. I suspect we'll see similar success with James Webb.
|
|
|
12-28-2021, 11:27 AM
|
#5
|
Thinks s/he gets paid by the post
Join Date: Mar 2012
Posts: 3,931
|
Quote:
Originally Posted by Sojourner
If anything does happen to fail, however, it won't get fixed. There is no way a manned mission could be developed and sent to the L2 point within the planned lifetime of the telescope. The L2 point is nearly 1,000,000 miles from Earth! That's four times farther than the moon. IMHO, the third poll option is a nonstarter.
|
How about SpaceX sending a Starship, capture it, ferry it back to the ISS for repair, then ferrying it back out? Sure, it couldn't do all of that today, but I would imagine they'd have the capability within the next few years.
|
|
|
12-28-2021, 11:40 AM
|
#6
|
Thinks s/he gets paid by the post
Join Date: Jan 2012
Posts: 2,593
|
Quote:
Originally Posted by njhowie
How about SpaceX sending a Starship, capture it, ferry it back to the ISS for repair, then ferrying it back out? Sure, it couldn't do all of that today, but I would imagine they'd have the capability within the next few years.
|
I suppose just about anything is possible... but I wouldn't hold my breath. Are the sunshields even retractable? I wouldn't imagine that retractability was part of the design specs, and I doubt it could be ferried back with the sunshields fully deployed. In any event, it would be an extraordinarily complex retrieve-and-repair mission.
|
|
|
12-28-2021, 11:40 AM
|
#7
|
Administrator
Join Date: Apr 2006
Posts: 23,036
|
I have confidence that it will work. Who would guess that the Voyager 1 spacecraft, launched in 1977, could respond to commands from mission control and fire its thrusters to conduct a trajectory correction maneuver 40 years later, when it was over 14 billion miles from Earth? But it did, and it's still motoring along today and communicating back to us here.
__________________
Living an analog life in the Digital Age.
|
|
|
12-28-2021, 11:43 AM
|
#8
|
Thinks s/he gets paid by the post
Join Date: Aug 2007
Posts: 2,872
|
I’m an optimist and believe it will work.
__________________
Eat, Drink and Be Merry.
|
|
|
12-28-2021, 11:52 AM
|
#9
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Mar 2017
Location: City
Posts: 10,351
|
Quote:
Originally Posted by Sojourner
I suppose just about anything is possible... but I wouldn't hold my breath. Are the sunshields even retractable? I wouldn't imagine that retractability was part of the design specs, and I doubt it could be ferried back with the sunshields fully deployed. In any event, it would be an extraordinarily complex retrieve-and-repair mission.
|
Yeah. Start with: "Is there even a hard point where a tow rope could be attached?" Then, "How much acceleration could the now-deployed structure be subjected to without damage?" My guess is that the small acceleration that would be permissible would result in an excruciatingly slow trip home.
__________________
Ignoramus et ignorabimus
|
|
|
12-28-2021, 12:18 PM
|
#10
|
Thinks s/he gets paid by the post
Join Date: Feb 2014
Location: Syracuse
Posts: 3,502
|
I'm optimistic it will work.
But I also think there are way more than 344 possible points of failure.
Screenshot_2021-12-28-14-15-45.jpg
__________________
“No, not rich. I am a poor man with money, which is not the same thing"
|
|
|
12-28-2021, 12:18 PM
|
#11
|
Thinks s/he gets paid by the post
Join Date: Mar 2012
Posts: 3,931
|
Quote:
Originally Posted by OldShooter
Yeah. Start with: "Is there even a hard point where a tow rope could be attached?" Then, "How much acceleration could the now-deployed structure be subjected to without damage?" My guess is that the small acceleration that would be permissible would result in an excruciatingly slow trip home.
|
When it was sent up, it was attached within the rocket fairing at some point on the structure, wasn't it? There's your hard point. I'd imagine it wouldn't be a tow rope - it would likely be captured/mated.
Regardless, I'm confident that at some point in the future, it will be a routine activity.
|
|
|
12-28-2021, 12:45 PM
|
#12
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Mar 2017
Location: City
Posts: 10,351
|
Quote:
Originally Posted by njhowie
When it was sent up, it was attached within the rocket fairing at some point on the structure, wasn't it? There's your hard point. ...
|
Oops! Blocked by the sun shield. Or the mirror. Or the secondary mirror. Or by the primary antenna ... Who knows?
__________________
Ignoramus et ignorabimus
|
|
|
12-28-2021, 12:52 PM
|
#13
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Jun 2006
Location: Boise
Posts: 7,882
|
Quote:
Originally Posted by GravitySucks
I'm optimistic it will work.
But I also think there are way more than 344 possible points of failure.
Attachment 41287
|
I should clarify - the 344 were single points of failure, meaning - approximately - that there are 344 different spots where if something goes wrong, there is no backup or alternative, and the result of the failure is catastrophic, meaning - approximately - that the thing won't work.
There are presumably thousands upon thousands of ways for things to go wrong that might have a workaround or will allow it to work somewhat.
__________________
"At times the world can seem an unfriendly and sinister place, but believe us when we say there is much more good in it than bad. All you have to do is look hard enough, and what might seem to be a series of unfortunate events, may in fact be the first steps of a journey." Violet Baudelaire.
|
|
|
12-28-2021, 01:00 PM
|
#14
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Jun 2006
Location: Boise
Posts: 7,882
|
I find it interesting that normally I am quite an optimist in general and about scientific stuff specifically.
I did some quick math. If each of those 344 points has an independent 50% chance of success, there's essentially zero chance of overall success. At 99% chance of success for each, it's about 3% overall. At 99.9% chance, it's about 70% overall. At 99.99% chance, it's about 96% overall.
As @OldShooter implies, I'm sure the NASA folks have done more and better math than me, and at $10B I'm sure they have some pretty high standards for deciding to launch the thing.
OTOH, the 344 items are ones we know about. Most failures on projects like this are due to things we didn't expect / predict / anticipate / test for / understand well enough. That input won't be over 16 bits. We know the units of measure. Soft foam couldn't damage a tough wing. Etc.
It'll be interesting to see. So far the second poll option has zero votes.
__________________
"At times the world can seem an unfriendly and sinister place, but believe us when we say there is much more good in it than bad. All you have to do is look hard enough, and what might seem to be a series of unfortunate events, may in fact be the first steps of a journey." Violet Baudelaire.
|
|
|
12-28-2021, 01:34 PM
|
#15
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Mar 2017
Location: City
Posts: 10,351
|
Quote:
Originally Posted by SecondCor521
... I did some quick math. If each of those 344 points has an independent 50% chance of success, there's essentially zero chance of overall success. At 99% chance of success for each, it's about 3% overall. At 99.9% chance, it's about 70% overall. At 99.99% chance, it's about 96% overall. ...
|
In the spacecraft world, numbers like 99.99% are do not come up in conversation. That number would be referred to as "four nines" and not considered to be particularly outstanding.
Of course, there are many difficulties in coming up and validating a probability number that small.
For context, the popular "Six Sigma" quality goal in manufacturing is coincidentally about six nines.
__________________
Ignoramus et ignorabimus
|
|
|
12-28-2021, 01:44 PM
|
#16
|
Recycles dryer sheets
Join Date: Jun 2021
Location: Centennial
Posts: 419
|
For another two months I am still employed at a Major Aerospace contractor and Program Manager for a Spacecraft program
What you are talking about with the single points of failure are the result of a Failure Modes and Effects Analysis (FMEA). The purpose of this analysis is to drive out all these potential failures and define work arounds for as many as are possible. On one mission I was involved with we lost a Horizon sensor which looks for the earth curvature for navigation. That caused the spacecraft to tumble and we developed a work around with Magnetometers (Reading Earths Magnetic Field). Other single point failures may have autonomous more simple work arounds. Still some can be mission ending like if Solar Panels don't deploy you have no power. Spacecraft are very complex and sophisticated systems. This is why they tend to take years and $$ to develop to work through and then test all the potential modes.
__________________
FIRE'd March 2022
|
|
|
12-28-2021, 01:55 PM
|
#17
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Jun 2006
Location: Boise
Posts: 7,882
|
Quote:
Originally Posted by Romer
For another two months I am still employed at a Major Aerospace contractor and Program Manager for a Spacecraft program
What you are talking about with the single points of failure are the result of a Failure Modes and Effects Analysis (FMEA).
|
A company I used to work for attempted to apply FMEA to our embedded firmware for a tech product with several hundred KNCSS. It didn't work very well for us because management considered it too time consuming and, quite frankly, we weren't very well trained in the methodology. We also found it somewhat hard to translate the ideas from the automotive industry to ours. Overall I think it would be a good technique if applied rigorously and thoroughly, but at the end of the day it still requires engineers to predict all the ways things could go wrong. And engineers are good at that but not perfect at it.
We had multiple other techniques that found most, but not all, of our bugs. One in particular caused a 100% field failure that we identified after shipping about 50K units but before customers found it. Knowing about the Intel Pentium bug history, I helped us navigate ours much better than Intel did theirs. Thankfully we had field upgradeable firmware and the bug fix was straightforward (change one variable name in one line of code).
__________________
"At times the world can seem an unfriendly and sinister place, but believe us when we say there is much more good in it than bad. All you have to do is look hard enough, and what might seem to be a series of unfortunate events, may in fact be the first steps of a journey." Violet Baudelaire.
|
|
|
12-28-2021, 01:58 PM
|
#18
|
Thinks s/he gets paid by the post
Join Date: Aug 2005
Location: Crownsville
Posts: 3,745
|
They finally launched that thing? I was actually on that project, back in the late 90s/early '00s. I'd forgotten about it. It used to be called "Next Generation Space Telescope" or NGST...partly because the project manager at the time was a big fan of "Star Trek: The Next Generation".
I remember he was also a big fan of the Comic Sans font...which as a result we used in a lot of monthly reports and presentations and such! Not the most professional look, in the world!
|
|
|
12-28-2021, 02:03 PM
|
#19
|
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
Join Date: Mar 2007
Posts: 14,328
|
It probably has a can of WD-40 in the cargo bay, so no worries.
|
|
|
12-29-2021, 12:32 PM
|
#20
|
Recycles dryer sheets
Join Date: Jun 2021
Location: Centennial
Posts: 419
|
From a post by the Chief Engineer at NASA JPL. I would bet those additional steps were to address many of the single point failures defined
The James Webb Space Telescope has successfully completed deploying both pallet structures of its sunshield, notching another milestone in the five-day-long process of unfurling the massive sunshield.
After deploying the forward pallet earlier today, the aft pallet finished deploying at approximately 7:27 p.m. EST on Tuesday, Dec. 28 (0027 GMT on Dec. 29).
"While the actual motion to lower the forward pallet from its stowed to its deployed position took only 20 minutes, and the lowering of the aft pallet took only 18 minutes, the overall process took several hours for each because of the dozens of additional steps required," NASA officials said in a statement.
"These include closely monitoring structural temperatures, maneuvering the observatory with respect to the sun to provide optimal temperatures, turning on heaters to warm key components, activating release mechanisms, configuring electronics and software, and ultimately latching the pallets into place."
__________________
FIRE'd March 2022
|
|
|
|
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
|
|
Thread Tools |
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Threads
|
|
|
|
|
|
|
|
|
|
|
|
|
» Quick Links
|
|
|