NASA - James Webb Space Telescope - Discussion Thread 2

[Zed_Noir]

Out of curiosity. How much will it cost to build a similar version of the JWST? Presuming the infrastructure exists to make new parts.

[LouScheffer]

Last post on a hypothetical Webb refueling mission:

It's certainly true that such a mission is entirely hypothetical, Webb was not designed for refueling, and it's not even launched and we don't know how well it will work. or what it might find.

But in about 10 years, assuming it's working well but running out of fuel, the exact same question will come up.  After all, it's a hugely expensive asset, and the question will be refuel or let it die and plan for a replacement. This is exactly what happened with the Hubble, when crewed servicing looked impossible for safety reasons.  A robot maintenance mission was seriously considered, as was letting it die, but in the end a crewed mission was used. 

Assuming Webb works as designed, it should have as spectacular a scientific career as the Hubble, and the pressure to keep it going will be high.  So let's revisit this in about 10 years.  The issues will be exactly those we are discussing now.

[AS_501]

Out of curiosity. How much will it cost to build a similar version of the JWST? Presuming the infrastructure exists to make new parts.

Good question.  Taking Ariane 5 out of the equation, it might be cheaper to build a performance-equivalent telescope with a much simpler (thus less costly) 6m monolithic mirror.  Perhaps the wider payload fairings on FH or SLS* would permit this?

*This a purely technical question, not meant to stir up anyone's wrath on SLS costs, etc. 

[AS_501]

Two additional points:

-  Since JWST will have a 5 to 10 year lifespan, it won't turn out the shear volume of observations generated by HST.  Many interesting objects and phenomena will have to be ignored for the sake of time.

-  Since JWST is not astronaut-serviceable, it won't benefit from new-technology upgrades as was possible with HST.

[niwax]

Out of curiosity. How much will it cost to build a similar version of the JWST? Presuming the infrastructure exists to make new parts.

Good question.  Taking Ariane 5 out of the equation, it might be cheaper to build a performance-equivalent telescope with a much simpler (thus less costly) 6m monolithic mirror.  Perhaps the wider payload fairings on FH or SLS* would permit this?

*This a purely technical question, not meant to stir up anyone's wrath on SLS costs, etc. 

Same problem as reusing Shuttle hardware now, the project has been so long and convoluted that there isn't a warehouse full of assembly jigs and a trained workforce that could just knock another few out. Ideally, we'd set up a small production run anytime these complex projects are attempted, possibly even with a staggered launch so faults can be fixed. But that's not possible using a government budget, a big reason JWST and other programs run off course is the yearly budgeting.

[ttle2]

Out of curiosity. How much will it cost to build a similar version of the JWST? Presuming the infrastructure exists to make new parts.

Good question.  Taking Ariane 5 out of the equation, it might be cheaper to build a performance-equivalent telescope with a much simpler (thus less costly) 6m monolithic mirror.  Perhaps the wider payload fairings on FH or SLS* would permit this?

*This a purely technical question, not meant to stir up anyone's wrath on SLS costs, etc. 

I'm not at all sure a monolithic mirror would be that much (if at all) simpler and cheaper to build. No one has built a 6 m monolithic mirror operating at cryogenic temperatures. Herschel is the largest at 3.5 m, but because it operated at longer wavelengths, its surface accuracy requirements etc. are much lower.

[Jim]

Good question.  Taking Ariane 5 out of the equation, it might be cheaper to build a performance-equivalent telescope with a much simpler (thus less costly) 6m monolithic mirror.  Perhaps the wider payload fairings on FH or SLS* would permit this?

Not true. 
a. A monolithic mirror would be too heavy.  And it would be more complex to fly.
b.  Even large follow ons to JWST are planned to be segmented.

[Jim]

Ideally, we'd set up a small production run anytime these complex projects are attempted, possibly even with a staggered launch so faults can be fixed. But that's not possible using a government budget, a big reason JWST and other programs run off course is the yearly budgeting.

not true.  It has nothing to do with gov't budgets.  Just no need for many of them.

[AS_501]

Good question.  Taking Ariane 5 out of the equation, it might be cheaper to build a performance-equivalent telescope with a much simpler (thus less costly) 6m monolithic mirror.  Perhaps the wider payload fairings on FH or SLS* would permit this?

Not true. 
a. A monolithic mirror would be too heavy.  And it would be more complex to fly.
b.  Even large follow ons to JWST are planned to be segmented.

"Monolithic" is obviously the wrong term.  Perhaps a segmented-mirror telescope that does not have to be unfurled?  Like Keck, albeit smaller.  You eliminate all those complex unfurling steps involving each segment.  I guess my fear is based on Galileo's high gain antenna, Lucy's solar array, etc.

PS:  I read somewhere that one of the designs of a JWST follow-on would have much larger aperture (segmented of course) and be robotically serviceable.

Thanks for the clarifications.

[Jim]

  I guess my fear is based on Galileo's high gain antenna, Lucy's solar array, etc.

Not remotely related.  Especially Galileo's antenna.  See MGS solar array.

So counter your irrational fear, I give you MER A & B, MSL, M2020, Inspiration, TDRS A-G, TDRS H-M, Phoenix, Insight, O-Rex, HEXAGON, GAMBIT, CORONA, (and supposably RHYOLITE/MAGNUM/ORION, CANYON/VORTEX, LACROS/ONYX).  Spacecraft with very complex mechanisms and deployments.

[libra]

A pretty apt name; it is quite logical to perform LUL during the.. lull between launch and arrival to SEL-2. (runs for cover).

[deadman1204]

Good question.  Taking Ariane 5 out of the equation, it might be cheaper to build a performance-equivalent telescope with a much simpler (thus less costly) 6m monolithic mirror.  Perhaps the wider payload fairings on FH or SLS* would permit this?

Not true. 
a. A monolithic mirror would be too heavy.  And it would be more complex to fly.
b.  Even large follow ons to JWST are planned to be segmented.

"Monolithic" is obviously the wrong term.  Perhaps a segmented-mirror telescope that does not have to be unfurled?  Like Keck, albeit smaller.  You eliminate all those complex unfurling steps involving each segment.  I guess my fear is based on Galileo's high gain antenna, Lucy's solar array, etc.

JWST must be folded so that it can fit on the rocket. That is the real limiting factor. Anything beyond what can fit inside the rocket faring must be folded up.

I also think you're confusing/combining two different things. The mirror must be expanded, but so must the sunshield. They are 2 different systems, though both must be folded up to fit on the rocket. JWST has the big folded up heat shield so that it can be passively cooled. Otherwise it would only have a few years of coolant, and then be unable to work at those temperatures.

[AS_501]

  I guess my fear is based on Galileo's high gain antenna, Lucy's solar array, etc.

Not remotely related.  Especially Galileo's antenna.  See MGS solar array.

So counter your irrational fear, I give you MER A & B, MSL, M2020, Inspiration, TDRS A-G, TDRS H-M, Phoenix, Insight, O-Rex, HEXAGON, GAMBIT, CORONA, (and supposably RHYOLITE/MAGNUM/ORION, CANYON/VORTEX, LACROS/ONYX).  Spacecraft with very complex mechanisms and deployments.

Per Jim's point, you can add Gaia, the galaxy imaging probe.  It also had a complex sunshade deployment (successful).

PS:  Imagine being the Lead Design, Assembly and Test Engineers when a spacecraft of probe suffers a critical deployment failure.  "Did I miss something?"  "Did a do something wrong during a procedure?"  Occupational hazard, I guess.

[bolun]

https://twitter.com/daily_hopper/status/1455253490360590336

[Blackstar]

PS:  Imagine being the Lead Design, Assembly and Test Engineers when a spacecraft of probe suffers a critical deployment failure.  "Did I miss something?"  "Did a do something wrong during a procedure?"  Occupational hazard, I guess.

Back around 2007 or so I was in a briefing where we saw some proposals from Northrop Grumman (builder of the JWST) for much bigger optical telescope designs. They had even more unfolding parts. Many deployments. They had some video animations of these (which might be on the internet somewhere). I think this was before the Advanced Technology Large-Aperture Space Telescope (ATLAST) which then led to LUVOIR. Anyway, the NG people were asked some questions about the deployments and they were rather dismissive about it. Yeah, they know what they're doing, they've done lots of deployments before, etc., hinting that they've done this kind of stuff with classified spacecraft and it's not a big deal, don't worry about it.

I don't think this went over well with our experts. There's a kind of game that some of these contractors play where they imply that they've solved all the problems doing classified stuff, so you don't have to worry about it when they get hired to build a civilian system like Webb--ignoring the fact that the civilian system might be much more complicated and challenging in some ways than the classified system.* They use their classified experience as a tool to shut down discussion and to reassure. Don't worry your pretty little head...

It wasn't much later after that than Webb ran into technical and cost and schedule problems. I'm sure that the Northrop Grumman people would insist that none of that was their fault. But I can still remember the arrogance of those engineers.

By the way, ATLAST is here, and if anybody finds those videos for even larger telescope deployments, you should post them:

https://asd.gsfc.nasa.gov/ATLAST/






*Examples: Hubble had much higher pointing requirements than any NRO satellite. And JWST has much higher cryo requirements than any other spacecraft.

[baldusi]

PS:  Imagine being the Lead Design, Assembly and Test Engineers when a spacecraft of probe suffers a critical deployment failure.  "Did I miss something?"  "Did a do something wrong during a procedure?"  Occupational hazard, I guess.

Back around 2007 or so I was in a briefing where we saw some proposals from Northrop Grumman (builder of the JWST) for much bigger optical telescope designs. They had even more unfolding parts. Many deployments. They had some video animations of these (which might be on the internet somewhere). I think this was before the Advanced Technology Large-Aperture Space Telescope (ATLAST) which then led to LUVOIR. Anyway, the NG people were asked some questions about the deployments and they were rather dismissive about it. Yeah, they know what they're doing, they've done lots of deployments before, etc., hinting that they've done this kind of stuff with classified spacecraft and it's not a big deal, don't worry about it.

I don't think this went over well with our experts. There's a kind of game that some of these contractors play where they imply that they've solved all the problems doing classified stuff, so you don't have to worry about it when they get hired to build a civilian system like Webb--ignoring the fact that the civilian system might be much more complicated and challenging in some ways than the classified system.* They use their classified experience as a tool to shut down discussion and to reassure. Don't worry your pretty little head...

It wasn't much later after that than Webb ran into technical and cost and schedule problems. I'm sure that the Northrop Grumman people would insist that none of that was their fault. But I can still remember the arrogance of those engineers.

By the way, ATLAST is here, and if anybody finds those videos for even larger telescope deployments, you should post them:

https://asd.gsfc.nasa.gov/ATLAST/






*Examples: Hubble had much higher pointing requirements than any NRO satellite. And JWST has much higher cryo requirements than any other spacecraft.

NG failed to differentiate "will" from "shall" in the JWST specifications, they justified because "younger engineers are not aware of the difference" and then "there's not enough budget to correct it". Which if you ask me, is so ridiculous that I wouldn't have dared to write that on a comedy.

[Targeteer]

November 16, 2021
MEDIA ADVISORY M21-156
NASA Invites Media to Webb Telescope Science Briefings

NASA will hold two virtual media briefings Thursday, Nov. 18, on the science goals and capabilities of the James Webb Space Telescope.

Participants will preview how the world’s largest and most powerful space science telescope will build on the discoveries of other missions to answer fundamental questions about the universe and its origins. Participants will also discuss Webb’s four scientific instruments, designed to study a wide range of objects in space, from planets and stars to galaxies and dark energy.

The briefings will livestream on NASA TV, the NASA app, and the agency’s website. All times are provided in Eastern.

11 a.m. – Briefing on Webb’s science goals with the following participants:

    Greg Robinson, Webb program director, NASA Headquarters in Washington
    John Mather, Webb senior project scientist, NASA’s Goddard Space Flight Center in Greenbelt, Maryland
    Antonella Nota, Webb project scientist and head of the ESA (European Space Agency) office at the Space Telescope Science Institute
    Sarah Gallagher, science advisor to the president, Canadian Space Agency
    Klaus Pontoppidan, Webb project scientist, Space Telescope Science Institute
    Amber Straughn, Webb deputy project scientist for communications, Goddard

2 p.m. – Briefing on Webb’s science instruments with the following participants:

    Eric Smith, Webb program scientist, NASA Headquarters
    Lee Feinberg, Webb optical telescope element manager, Goddard
    Marcia Rieke, principal investigator for Webb’s Near-Infrared Camera, University of Arizona
    Pierre Ferruit, principal investigator for Webb’s Near-Infrared Spectrograph, ESA
    Gillian Wright, European principal investigator for Webb’s Mid-Infrared Instrument, U.K. Astronomy Technology Centre
    René Doyon, principal investigator for Webb’s Near-Infrared Imager and Slitless Spectrograph and Fine Guidance Sensor, University of Montreal

To participate by telephone, media must RSVP no later than two hours before the start of each briefing to Alise Fisher at: [email protected]. Media and members of the public may also ask questions on social media using #NASAWebb.

NASA’s media accreditation policy for virtual and onsite activities is available online.

NASA’s Curious Universe podcast also will debut a special Webb mini-series Tuesday, Nov. 23, exploring the mission’s science, engineering, people, and launch. NASA will release episodes every Tuesday leading up to Webb’s Dec. 18 launch. The trailer is available online.

The Webb telescope, an international partnership with the European and Canadian space agencies, will explore every phase of cosmic history – from within our solar system to the most distant observable galaxies in the early universe, and everything in between. Webb will reveal new and unexpected discoveries, and help humanity understand the origins of the universe and our place in it.

For more information about the Webb mission, visit:

https://nasa.gov/webb

[SPKirsch]

https://twitter.com/haygenwarren/status/1462527773302575111

After separating from an Ariane 5 rocket this December, the complex six-month-long commissioning process for the James Webb Space Telescope will begin.

I sat down with Keith Parrish, Observatory Manager, to discuss JWST's commissioning process ⬇️

https://www.nasaspaceflight.com/2021/11/commissioning-jwst-1/

[zubenelgenubi]

Moderator reminder:
Launch campaign content and discussion in the launch thread, in the European launch sub-forum.

[faramund]

I'm a frequent reader of the Economist, and while I think its very good, it does still make mistakes. I was reading their article of JWST (https://www.economist.com/science-and-technology/2021/11/23/a-new-eye-on-the-heavens (but paywall)) and it had the following text:

The cloud of delay, meanwhile, has had silver linings. ...
There is also a chance that the wait will permit the telescope’s lifetime to be extended. It will probably use up the thruster fuel needed to keep it on station within a decade. In the past, that would have been that. In light of advances in space technology, however, NASA has installed an arrangement which would let a service vessel dock and offer a top-up.

I'd be very surprised if the Economist, just made this up, but maybe they misinterpreted something they'd been told, but what that was, I have no idea.

Although I found (https://space.stackexchange.com/questions/38389/is-it-possible-to-refuel-the-james-webb-space-telescope) which states that the German wikipedia for JWST has an unsourced statement saying this. Maybe that's the source. Although that still leads to the question of what's that sources source.