Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

What if JWST fails?!

  • Please log in to reply
35 replies to this topic

#26 llanitedave

llanitedave

    Humble Megalomaniac

  • *****
  • Posts: 29381
  • Joined: 25 Sep 2005
  • Loc: Amargosa Valley, NV, USA

Posted 26 August 2019 - 10:52 PM

Don't they read everything that gets posted?

Not if they want to remain sane.


  • Joe1950 likes this

#27 CygnuS

CygnuS

    Apollo

  • -----
  • Posts: 1365
  • Joined: 11 Jul 2011
  • Loc: The Great Rift

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. 


  • llanitedave and Joe1950 like this

#28 t_image

t_image

    Gemini

  • -----
  • Posts: 3229
  • Joined: 22 Jul 2015

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....


  • Joe1950 likes this

#29 t_image

t_image

    Gemini

  • -----
  • Posts: 3229
  • Joined: 22 Jul 2015

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....


  • Joe1950 and HouseBuilder328 like this

#30 HouseBuilder328

HouseBuilder328

    Explorer 1

  • -----
  • Posts: 72
  • Joined: 24 Apr 2019
  • Loc: Raleigh, NC

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!


  • Joe1950 and Sleep Deprived like this

#31 figurate

figurate

    Apollo

  • *****
  • Posts: 1055
  • Joined: 09 Feb 2013
  • Loc: Metro North Texas

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.  



#32 sg6

sg6

    Fly Me to the Moon

  • *****
  • Posts: 5949
  • Joined: 14 Feb 2010
  • Loc: Norfolk, UK.

Posted 05 September 2019 - 01:41 PM

If it fails someone will have to identify the reason(s).

And it could well become a case of find a suitable person/company. I somehow suspect that "time" will not be identified as a cause.

 

It does seem to have become a "hot potato" as the saying goes. If I were an insurer I think I would pass on covering this one.

 

Will the opening of the mirrors be "close" to earth or out at the Legrange point? Either I expect means no maintenance option - no shuttle. Wonder if someone should have pulled the plug and made a decision to put the resources into the next generation of shuttle craft. Outcry at wasted time and money up until that point but could have delivered greater benefits.

 

Is James Webb still around?



#33 EJN

EJN

    Skylab

  • *****
  • Posts: 4400
  • Joined: 01 Nov 2005
  • Loc: Between what is and what's not there

Posted 05 September 2019 - 03:09 PM

Will the opening of the mirrors be "close" to earth or out at the Legrange point?


The mirrors will not unfold until it reaches the LaGrange point.

#34 Mister T

Mister T

    Surveyor 1

  • *****
  • Posts: 1773
  • Joined: 01 Feb 2008
  • Loc: Upstate NY

Posted 06 September 2019 - 05:51 AM

 

 

 

Is James Webb still around?

He's the pilot smirk.gif


  • physik and happylimpet like this

#35 Joe1950

Joe1950

    Cosmos

  • *****
  • Posts: 9678
  • Joined: 22 Aug 2015

Posted 09 September 2019 - 12:08 PM

James E Webb. 1906-1992.

 

I read that the entire telescope, that is the upper part with the mirrors, sensors et al, and the lower assembly, that being the light/heat shields, has now been assembled, and the entire scope is complete. However, interconenctive wiring, etc must be done and tested. Then complete systems testing will begin on the entire assembled spacecraft.

 

Launch is scheduled  for March 30, 2021.


  • Sleep Deprived likes this

#36 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 82974
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 10 September 2019 - 01:09 AM

The costly saga of the JWST...

 

https://ecogirlcosmo...story-of-costs/

 

https://www.scientif...ronomy-suffers/

https://www.gao.gov/...ucts/GAO-19-189

 

https://www.science2...assembly-241299


  • Joe1950 likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics