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James Webb Space Telescope emerges successfully from final thermal vacuum test

phys.org

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Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#121

Post by nullwasamistake »

mikepurvis wrote: post #59
nullwasamistake wrote: post #29

Earlier quoted context omitted.

If it tears bad it's technically possible to send up a shield that floats near the telescope. There were some plans for that way back during the design phase if I remember right. Still wouldn't be cheap or easy

It looks from the renders like the telescope has solar panels, antennas, etc on the sun/earth-side of the shield. Wouldn't sending a standalone shield screw that up as it would shade them?

Probably, although you could shape the shield not to.

It's still far more complex than just attaching the thing right to the telescope. And glancing starlight leaking in between the shield and the telescope could be a big problem.

I looked it up, the original proposal was actually to use a mobile shield to occlude far away stars for direct planet imaging. I think a similar approach could "fix" JWT but let's hope we never get there

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#122

Post by AWildC182 »

ExodusOrbitals1 wrote: post #100
AWildC182 wrote: post #70

Earlier quoted context omitted.

With launch costs falling and hardware getting smaller/lighter it's getting less conservative. It used to be everything was C99, VxWorks and SPARC or worse but a lot of companies are starting to look at newer technologies. Good luck finding one of those projects right now but it is happening.

You can have a look at ours: https://www.exodusorbitals.com

Cube sats don't count :)

The requirements and budgets for them mean that they're much more expendable than something flying on a full size bus. As such, the level of risk tolerance is much higher.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#123

Post by bdamm »

mikeash wrote: post #106
lostmyoldone wrote: post #46

Earlier quoted context omitted.

Likewise. My train of thought goes like "So what if it fails? There's a lot of money sunk into that! Well, maybe someone would actually decide it's worth going to the L2 to fix it, wouldn't that be cool!!" So yeah, not the only idiot...

If SpaceX’s Starship/Super Heavy (née BFR) actually pans out, it should be able to easily perform this mission.

With the irony being that if BFR pans out, this mission could have ended up being launched on it and eliminate a pile of complexity in the process. The mirrors wouldn't have to be hinged, for example.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#124

Post by bdamm »

gootdude wrote: post #115
TremendousJudge wrote: post #113

Earlier quoted context omitted.

Is it known how long it would last? Wikipedia doesn't say anything about this issue

The mission is minimum of 5 years with maximum 10 years based on the fuel. https://jwst.nasa.gov/faq.html#howlong

What a shame. The mission won't be operational as long as its delays. After all that I'd at least hope there could be an option for re-fueling, but I bet there isn't.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#125

Post by Rebelgecko »

neurostimulant wrote: post #86
NikolaeVarius wrote: post #7

Man, I really want this telescope to succeed its mission, but I just can't get over how complex its deployment procedure is. I am extremely pessimistic about it actually managing to deploy as planned.

For a project this magnitude, I think they should build a spare telescope or two to account for launch failures. Or is it not how the space industry operates?

The costs don't scale quite as well as you'd expect. Actually building, testing, and transporting the thing is really expensive. If you build 2, it's still a lot of expensive bespoke parts. Maybe if you build dozens the economies of scale start to pay off

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#126

Post by jandrese »

gootdude wrote: post #115
TremendousJudge wrote: post #113

Earlier quoted context omitted.

Is it known how long it would last? Wikipedia doesn't say anything about this issue

The mission is minimum of 5 years with maximum 10 years based on the fuel. https://jwst.nasa.gov/faq.html#howlong

After 10 years it will probably need more than just fuel. And doing maintenance in orbit, especially way out in the L2 point is easier said than done. Probably easier to build a new satellite with even more capability to replace it, except of course that the JWT is famously behind schedule and over budget and a more sophisticated replacement probably won't be any easier to build.

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#127

Post by yread »

skizm wrote: post #34

Anyone know if there are any well paying jobs in space programs of any kind? I've been seeing a growing number of reputable universities offering a wider range of space / aerospace / engineering offerings* and I've been getting curious what's out there. Only issue is, a lot of places I looked pay well below market rates :/ (at least for software engineers). I'll admit my expectations might be off considering I've bee…

ESA in Europe has decent salaries and you don't pay income taxes from them

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#128

Post by Rebelgecko »

Damorian wrote: post #51
skizm wrote: post #34

Anyone know if there are any well paying jobs in space programs of any kind? I've been seeing a growing number of reputable universities offering a wider range of space / aerospace / engineering offerings* and I've been getting curious what's out there. Only issue is, a lot of places I looked pay well below market rates :/ (at least for software engineers). I'll admit my expectations might be off considering I've bee…

Just adding on to this. The government funded research labs and DoD contractors I've had offers from have been seriously sad, which makes me concerned on the quality of their missions, personally. Also it's frustrating because I'd much rather work in that space. I'm a senior dev making ~140k and was just offered 80k in a higher cost of living to manage a team of 10 developers with TS clearance working on spy satellit…

That company might've just been lowballing you. I'm much closer to your current salary at my job and I'm not management or a particularly senior developer. If that was a job direct from the government, they might've put you on the GS scale, which sucks (although you don't need as much in retirement savings if you have a pension that pays 40% of your salary)

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#129

Post by ATsch »

petschge wrote: post #120
HeadsUpHigh wrote: post #117

Earlier quoted context omitted.

You can combine multiple mirrors like they did with the black hole photo.

This requires keeping the baseline constant to a fraction of the wave length. In other words you would have to position the satellites with a accuracy of 100 nm relative to each other. In other words: No we can not (, yet. For a decade at least).

wasn't there an experiment that used laser interferometry to calculate the precise distances between a constellation of three satellites? I assume something like that could work?

Re: James Webb Space Telescope emerges successfully from final thermal vacuum test

#130

Post by Rebelgecko »

TeMPOraL wrote: post #72
mhb wrote: post #35

Earlier quoted context omitted.

Is there any economy of scale? Why not wait until the first one fails to build another one?

Because that requires keeping all the specialized machinery and knowledge alive for the duration of the whole project. Given the length of this project, I wouldn't be surprised if at this point NASA couldn't order a second one built even if they wanted to. The unfortunate thing about advanced technology is that if you don't use it, you lose it. More specifically, you lose the research and machining setups and people…

Unfortunately that's already the case with many long running projects. A friend of mine that works on JWST recently fixed a mistake that was made by someone who retired 10 years ago.
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