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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

#21

Post by NikolaeVarius »

FrojoS wrote: post #15
d33 wrote: post #8

Earlier quoted context omitted.

Could you elaborate on the complexity, comparing it to other complex science projects that succeeded? I'm a layman, curious if this is actually riskier than what humanity has done so far.

This video explains it very well. https://www.youtube.com/watch?v=k8yRDrl76d0 Half way through the video, I understood why it's so expensive and risky. On the other hand, Apollo 11 had many 'firsts' that couldn't be tested before the actual mission and it worked out 'first shot'. Of course there were some problems and Apollo 13 showed that the odd's where not too good.

Huge difference is that Apollo had highly trained human beings on board to fix things that could not be planned for. There were also 10 previous missions to Apollo 11 to work out the kinks, with one failing with loss of life.

JW is not designed to be fixed or fail, nor are there training runs. It HAS to work first shot.

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

#22

Post by gameswithgo »

afpx wrote: post #18
afpx wrote: post #14

Earlier quoted context omitted.

That's a bit cynical. There are many examples of NASA missions that had far exceeded the original expectations.

Plus, check out some of the engineering on this $10B masterpiece. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201800... In my opinion, much better for Human advancement than the typical $10B infrastructure project

indeed, I would take a bunch of 10billion scientific instruments over trillion dollar fighter jets or mid east military incursions any day.

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

#23

Post by scrozart »

afpx wrote: post #14
nn3 wrote: post #9

At this price point it better be good. It has to make up for all the other astrophysics missions it killed with its (near) endless budget overruns.

That's a bit cynical. There are many examples of NASA missions that had far exceeded the original expectations.

Yup. Hubble was no different; took forever and cost more than expected. These are novel scientific instruments, not helicopters.

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

#24

Post by 3JPLW »

okket wrote: post #16
maxxxxx wrote: post #12

Earlier quoted context omitted.

Considering how much camera sensors have improved in the last few years I wonder how outdated these sensors are (or not) Edit: makes me also wonder if with all the delays they upgrade any equipment in the meantime.

Hard to tell, since you can't use off-the-shelf sensors. They have to withstand the harsh environment in space, for a very long time, without any maintenance.

They're also specifically designed to operate in absurdly low temperatures — one in fact requires temperatures under 7 Kelvin and so in addition to the sun shield there's a mechanical cooler.

https://en.wikipedia.org/wiki/MIRI_(Mid-Infrared_Instrument)

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

#25

Post by eafkuor »

FrojoS wrote: post #15
d33 wrote: post #8

Earlier quoted context omitted.

Could you elaborate on the complexity, comparing it to other complex science projects that succeeded? I'm a layman, curious if this is actually riskier than what humanity has done so far.

This video explains it very well. https://www.youtube.com/watch?v=k8yRDrl76d0 Half way through the video, I understood why it's so expensive and risky. On the other hand, Apollo 11 had many 'firsts' that couldn't be tested before the actual mission and it worked out 'first shot'. Of course there were some problems and Apollo 13 showed that the odd's where not too good.

Wow, this video is mindblowing.

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

#27

Post by java-man »

what puzzles me all the time is why not build two instead. it looks like the R&D portion of the budget might be greater than the actual manufacturing cost, so building two would be less than 2x the price.

if one launch fails, we've got a backup. if both launch, we have two instruments deployed.

why don't we do it??

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

#28

Post by sandworm101 »

scrozart wrote: post #23
afpx wrote: post #14

Earlier quoted context omitted.

That's a bit cynical. There are many examples of NASA missions that had far exceeded the original expectations.

Yup. Hubble was no different; took forever and cost more than expected. These are novel scientific instruments, not helicopters.

Hubble's cost structure is complicated. It is essentially a modified spy satellite and so much of its development costs were shrouded. We don't know how much was saved, or how much of Hubble's public budget was used on other projects. JWST is different. It is a unique object with no equivalent. Its cost structure is therefore not comparable to Hubble.

(Or I am wrong. Maybe JWST is a modified version of a super-secret unannounced program and its budget is covering the development costs of that spying program. Given the testing scheduled I doubt this, but it remains a possibility.)

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

#29

Post by nullwasamistake »

enceladus_ice wrote: post #11
d33 wrote: post #8

Earlier quoted context omitted.

Could you elaborate on the complexity, comparing it to other complex science projects that succeeded? I'm a layman, curious if this is actually riskier than what humanity has done so far.

I think a big amount of the complexity comes from the folded up sunshield. I remember it had torn during a test deployment last year. Here is a quick animation showing the whole deployment process: https://www.youtube.com/watch?v=vpVz3UrSsE4

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
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