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What if JWST fails?!

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#1 Lucullus

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Posted 22 August 2019 - 05:55 PM

For several times the launch of the James Webb Space Telescope, Hubble's successor, had been postponed and is now forseen to happen in 2021. Obviously the engineers need this time to make sure everything works as it should and the primary mirror and truss structure holding the secondary mirror unfold (- to what sigma certainty are they probably required to "guarantee" that what they send up will work grin.gif ??? Any insights here as to what's the rule in space flight? The more expensive the more sigma?)

Anyway, as the JWST has now eaten roughly around almost 9 billion $ over the length of the entire project there is surely a huge pressure on NASA to make sure that it works.

Now my big question:

 

What if anything goes wrong leaving the spacecraft in a state not able to conduct useful science, e.g. if the truss structure does not unfold as planned? What hellish fanfares will hail down from Concress and sponsors?

How might the NASA and it's science program look like if the 9-billion-$ JWST mission was in vain besides the technological research conducted?


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#2 DaveC2042

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Posted 22 August 2019 - 06:44 PM

It's worth remembering that these projects tend to build in a lot of redundancy and fail-safes.  Remember the Hubble initially 'didn't work', but was fixed remotely.

 

I'm not even remotely an expert, but I suspect that short of blowing it up on the launchpad, any amount of stuff going wrong will still result in some level of success.



#3 Frank Otsuka

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Posted 22 August 2019 - 07:17 PM

If it fails, it will not matter - just money lost.

 

The problem is in the overall project assumption. It assumes the package must be lifted in

one piece. The constraints of weight and nose cone size is 1960's thinking. This matches the

idea of throw-away boosters - something that SpaceX has shown to be a waste of money.

 

We can launch the whole thing in pieces and assemble in place as we have come a long way in

robotics. Done in pieces, there is no size limit to the final scope. It can even be

put into service before completion. Initial perfection (6 sigma?) is less of a problem since

the original constructor robots are on site to act as maintenance robots.
Finally, given the speed of tech, there will be new electronics and optics to add in the

future.  Again, robot crew.

 

I think this will be the last of large scopes done this way. Things have changed.

 

Next stop - Lagrange points outside of Earth's. Venus, Mars and beyond. Better have reservations!


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#4 iwannabswiss

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Posted 22 August 2019 - 07:19 PM

It's worth remembering that these projects tend to build in a lot of redundancy and fail-safes.  Remember the Hubble initially 'didn't work', but was fixed remotely.

 

I'm not even remotely an expert, but I suspect that short of blowing it up on the launchpad, any amount of stuff going wrong will still result in some level of success.

Unfortunately it'll be too far away to send someone up to repair so it has to work the first time.



#5 Bean614

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Posted 22 August 2019 - 07:46 PM

DaveC2042 wrote--- "but was fixed remotely.".  WRONG!!  Please do not spread misinformation!  The Hubble was fixed twice, BOTH times by sending astronauts to it in the space shuttle!  Both fixes were long, grueling affairs.  If the same type of flaw befalls the JWST, it would require a similar trip, which unfortunately, would not be possible.  The JWST will be in a far higher and different type of orbit.


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#6 Sleep Deprived

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Posted 22 August 2019 - 07:55 PM

Anyway, ALL of our space probes/satellites are subject to the possibility of failure, whether it is a failure of the payload, or of the rocket.  We've had failures (and successes, of course) in the past, and we will have them in the future.  I doubt there are any launches that happen where NASA thinks it will fail.  Luckily, nowadays, they are pretty good at getting these things to work as designed.   Or spectacularly exceed the design requirements (Remember Spirit and Opportunity?  They were only supposed to last 90 days).  Like someone upthread said, if it fails miserably, it is probably just money lost.  If it happens, I expect they would re-evaluate the need to spend that money again and decide whether to give it another go.  NASA has been known to say after a failure that even a failure is an opportunity to learn how to do better.  If they decide (and can get the funding, which is probably the biggest constraint) to give it a second try, they will darn-tootin' do what they can to prevent a repeat performance.  For astronomers around the world, it would suck, big time, but to everyone else, it would just be another spectacular and expensive thud ---- they probably wonder why we are spending the money on such a thing in the first place.

 

If you want a real answer (and not opinions) to your question, you should ask NASA.  Good luck getting an honest, straight-forward, reply.


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#7 Joe1950

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Posted 22 August 2019 - 08:22 PM

There are hundreds of electronic and mechanical procedures that must go perfectly for the JWST to be fully operational.

 

I recall somewhere reading that it isn't good for the mechanical elements to sit for too long without being used. The longer they sit idle, the more likely is possible failure.

 

Anyone know if that is true? I would think NASA would be aware of such a situation. Most of the components have been finished and ready to go for several years. Can they check every single operation right before launch?

 

I hope they didn't use any of that Asian telescope grease to lubricate anything.

 

And, why couldn't the thing be positioned in a geostationary earth orbit in the earth's shadow. At least close enough for a manned repair to be possible at some point.

 

It just seems like a roll of the dice with an extremely complicated machine and no contingency possible.



#8 EJN

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Posted 22 August 2019 - 08:38 PM

I recall somewhere reading that it isn't good for the mechanical elements to sit for too long without being used. The longer they sit idle, the more likely is possible failure.

Anyone know if that is true? I would think NASA would be aware of such a situation. Most of the components have been finished and ready to go for several years.

 

The Galileo probe to Jupiter was delayed 3 years by the Space Shuttle Challenger disaster

(it had been designed to be deployed by the shuttle).

 

When it was finally deployed, the high-gain antenna failed to properly unfold, severely impacting the

bitrate of sending data back because only the low-gain antenna was useable.

 

The cause was traced to the lubricant used becoming gummy during the 3 year storage period.


Edited by EJN, 22 August 2019 - 08:47 PM.

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#9 Joe1950

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Posted 22 August 2019 - 09:08 PM

That may have been what initiated the article I read a couple years ago. Lubricants sitting for extended periods of time. I hope that's been considered and addressed for this mission. 


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#10 DaveC2042

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Posted 22 August 2019 - 09:23 PM

DaveC2042 wrote--- "but was fixed remotely.".  WRONG!!  Please do not spread misinformation!  The Hubble was fixed twice, BOTH times by sending astronauts to it in the space shuttle!  Both fixes were long, grueling affairs.  If the same type of flaw befalls the JWST, it would require a similar trip, which unfortunately, would not be possible.  The JWST will be in a far higher and different type of orbit.

I stand corrected.



#11 Joe1950

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Posted 22 August 2019 - 09:28 PM

Have a seat. We all make mistakes and I'm sure you were not spreading misinformation.

 

C'mon Bean. Lighten up! grin.gif


Edited by Joe1950, 22 August 2019 - 09:28 PM.


#12 EJN

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Posted 23 August 2019 - 09:17 AM

That may have been what initiated the article I read a couple years ago. Lubricants sitting for extended periods of time. I hope that's been considered and addressed for this mission.

NASA has implemented a strategy to prevent issues like that in future missions: if it is supposed to move, WD-40. If it is not supposed to move, duct tape.
:yay:

Edited by EJN, 23 August 2019 - 03:08 PM.

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#13 BillP

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Posted 25 August 2019 - 09:32 PM

How might the NASA and it's science program look like if the 9-billion-$ JWST mission was in vain besides the technological research conducted?

 

$9B does sound like a lot.  But in terms of overall spending of the country it is not really.  A Nimitz class aircraft carrier costs about $37B in comparison.  So from the Congressional standpoint $9B probably not going to do any major harm for NASA funding.

 

The JWST's primary scientific mission has four key goals: 1) to search for light from the first stars and galaxies that formed in the Universe after the Big Bang, 2) to study the formation and evolution of galaxies, 3) to understand the formation of stars and planetary systems, and 4) to study planetary systems and the origins of life.

 

The bigger question in my mind, is that given other priorities we need here on Earth, is $9B for cosmological pure science worth it at all?  Kind of silly wasting all that money just to peer further back in cosmological time to try to figure out what might have happened is the distant past!  Now some may say the 4th goal has some practicality as we might find another planet that can really support human life.  But big deal as we can never get there in any practical amount of time nor move the world's population there in an emergency.  So a fruitless endeavor given more pressing matters here at home.

 

Really, I would have liked NASA to nix this idea for wasting $9B on JWST and put it toward something more practical, like planetary defense against asteroids.  Would make a good cartoon image showing one scientist looking at their new JWST data as another scientist looks at their NEO data and turning to the JWST scientist letting them know they will not have enough time to analyze any of their JWST mission data!


Edited by BillP, 25 August 2019 - 09:34 PM.

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#14 CygnuS

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Posted 25 August 2019 - 10:26 PM

The public seems to like looking back at the earliest galaxies so this is a bargain compared to CERN considering that it cost more than that to find the Higgs Boson, something the public is not much interested in at all. Don't kill the messenger. I'm not saying Higgs is less exciting but if you asked 100 people on the street what a galaxy is 80 of them would probably know (the rest would confuse it with the Solar System or Universe) but you'd be lucky to find one who knew the Higgs Boson. 


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#15 EJN

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Posted 26 August 2019 - 11:56 AM

Bottom line, if JWST fails the suicide hotline will be getting a lot of calls.
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#16 Alien Observatory

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Posted 26 August 2019 - 01:09 PM

My thoughts are JWST will fail to some degree...its is Large and Complex and will be a long way from home at L2... so for me it is just a question of how much data NASA will get before it becomes unusable and how much data is collected before they call it "Successful"...of course if could just work perfectly as planned (maybe)...Pat Utah :)



#17 llanitedave

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Posted 26 August 2019 - 02:56 PM

I'll go out on a limb and predict it will be an amazing success.

 

That's a prediction, not a prophecy.  I don't actually know what I'm talking about.


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#18 rutherfordt

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Posted 26 August 2019 - 04:37 PM

You know, people who complain about the spending on the space program often seem to think that the money spent by NASA is being put into a rocket and launched to to space to be forever lost-- that's not how it works.  The money spent on this (or any other space project) goes to pay wages and buy raw materials from suppliers.  Those people in turn spend that money on housing, clothing, food and lots of other things-- all of which is exactly what the detractors say that the money should be spent on-- I don't get it at all.


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#19 CygnuS

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Posted 26 August 2019 - 10:36 PM

I'll go out on a limb and predict it will be an amazing success.

 

That's a prediction, not a prophecy.  I don't actually know what I'm talking about.

I'm going to join you on that limb. I hope the weight of all our optimism doesn't break it. 



#20 llanitedave

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Posted 26 August 2019 - 10:52 PM

Don't they read everything that gets posted?

Not if they want to remain sane.


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#21 CygnuS

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Posted 28 August 2019 - 11:19 AM

Not if they want to remain sane.

LOL You're right. It's sorta like a mother with a son who's bad all the time. If she watched everything the boy did she'd go crazy so often she never looks. My mom never paid any attention to me. 


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#22 t_image

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Posted 28 August 2019 - 02:32 PM

There are hundreds of electronic and mechanical procedures that must go perfectly for the JWST to be fully operational.

 

I recall somewhere reading that it isn't good for the mechanical elements to sit for too long without being used. The longer they sit idle, the more likely is possible failure.

 

Anyone know if that is true? I would think NASA would be aware of such a situation. Most of the components have been finished and ready to go for several years. Can they check every single operation right before launch?

 

I hope they didn't use any of that Asian telescope grease to lubricate anything.

 

And, why couldn't the thing be positioned in a geostationary earth orbit in the earth's shadow. At least close enough for a manned repair to be possible at some point.

 

It just seems like a roll of the dice with an extremely complicated machine and no contingency possible.

Although it may seem easy to just armchair quarterback how the JWST team should do things,

I'm more confident with their ideas than random forum posters on the internet who think they have a better way.

 

For example:

the idea that something in geostationary orbit will stay (or even regularly be) in the Earth's shadow is quite misinformed. Remember the "seasons" of the year? Only on the Equinoxes is the Sun planar with the Earth for the Earth's shadow to even hit the Geobelt.

And if you are trying to conceive of some complex inclined geosynchronous orbit which would chase the Earth's shadow, you've violated the goal of your intended point: simplicity and cost reduction.

 

As to parts going bad,

I think we are sensitized in daily lives to crappy workmanship consumer mechanical parts and electronics shipped from elsewhere.

A well-built device,even if complex, can be more reliable that one would think....


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#23 t_image

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Posted 28 August 2019 - 02:45 PM

If it fails, it will not matter - just money lost.

 

The problem is in the overall project assumption. It assumes the package must be lifted in

one piece. The constraints of weight and nose cone size is 1960's thinking. This matches the

idea of throw-away boosters - something that SpaceX has shown to be a waste of money.

 

We can launch the whole thing in pieces and assemble in place as we have come a long way in

robotics. Done in pieces, there is no size limit to the final scope. It can even be

put into service before completion. Initial perfection (6 sigma?) is less of a problem since

the original constructor robots are on site to act as maintenance robots.
Finally, given the speed of tech, there will be new electronics and optics to add in the

future.  Again, robot crew.

 

I think this will be the last of large scopes done this way. Things have changed.

 

Next stop - Lagrange points outside of Earth's. Venus, Mars and beyond. Better have reservations!

The concept of modular construction isn't new, it is just there are design and technology challenges to realize it.

The JWST is about how we know how to do things now.

 

One assumption your idea misses "the whole thing in pieces and assemble in place,"

is that "up there" isn't a necessarily friendly place like hollywood portrays. You have shifting thermodynamics and things whizzing around at high speeds like micrometeorites, Solar winds, inertia issues, etc.....

So any of the bits have to be self-contained, tethered and protected modules. That's not really how we build something on the ground.

I'm sure someday the "space construction" industry will be booming business, but it's still primordial.

Interestingly you never see movies or tv shows that show things being built in space, (except maybe the Death Star)......

I think we assume it'd be easy....


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#24 HouseBuilder328

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Posted 01 September 2019 - 11:01 AM

I'll go out on a limb and predict it will be an amazing success.

 

That's a prediction, not a prophecy.  I don't actually know what I'm talking about.

I'm going to join you on that limb. I hope the weight of all our optimism doesn't break it. 

 

I'll be the 3rd to just join you - I have a lot of optimism that this will work and we will see amazing photos of new places with this telescope!


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#25 figurate

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Posted 04 September 2019 - 08:09 PM

It would certainly be a magnificent achievement for them to pull it off, although from the beginning I found myself somewhat in disbelief as to the workability of the transformer-put-into-orbit nature of the design, done to optical tolerances to boot (and anyway, that's so 2010!). I'm hopeful.

 

And as to the robots/modular assembly idea, just remember how telescope optics are coated: in a vacuum chamber with carefully monitored vaporized deposits. That would seem to rule out the use of maneuvering reaction jets for fear of contaminating optical surfaces, and reaction wheels might not be an effective substitute in such a scenario.  




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