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James Webb is fully deployed

nasa.gov

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Re: James Webb is fully deployed

#441

Post by jibalt »

ducktective wrote: post #31
binarymax wrote: post #29

Earlier quoted context omitted.

The sequential deployment process had many possible individual points of failure along the way - if any step went wrong then the full deployment failed.

well yes, but wouldn't we refer to them simply by "points of failure" not "single"?

It's a point where a single failure causes system failure, but that's a lot more words. These things tend to get whittled down to "terms of art", the meaning of which is understood by those trained in the art. It's perhaps best to just call it an SPOF and then people will hopefully google it to find out what that means.

Re: James Webb is fully deployed

#442

Post by jibalt »

stolsvik wrote: post #289
BurningFrog wrote: post #236

Earlier quoted context omitted.

In your body, the brain, heart and lungs are all single points of failure. If either one fails, you die.

You have two lungs, though. One can fail and you will still live. As with kidneys. Strange that there is only one heart.

Lungs and kidneys can work independently, but two pumps running at the same time on the same circuit will cause more failures ... it's like parallel vs. sequential circuits.

Re: James Webb is fully deployed

#443

Post by jibalt »

WalterBright wrote: post #69
ducktective wrote: post #26

Earlier quoted context omitted.

>344 single points of failure How can a system have more that one single point of failure?

Airliners are designed so that no single failure can bring it down.

Tell that to the passengers on the two 737 MAX planes that crashed.

Re: James Webb is fully deployed

#444

Post by ilstormcloud »

bmitc wrote: post #418
claaams wrote: post #415

Earlier quoted context omitted.

The point of the telescope is to capture IR light from space, if the telescope itself were generating IR light itself it would disrupt the sensor and data that it collects. Part of why its going to take so long for it to begin operating is that it needs to cool down to ultra cold temperatures before beginning operation.

Who said anything about generating infrared light? And I don't know what your last sentence is in reference to. Yes, it needs to cool down. Why is that relevant to this discussion other than what's already mentioned about that being a downside to operating cameras? From the article so people can just debate NASA's own reporting: > Although infrared or thermal-imaging cameras on the cold side could obviate the need fo…

The JWST has an extremely sensitive IR camera. And it is going to cool down to near absolute zero so that the IR sensors don't get flooded with radiation from the rest of the telescope. Because it will get so cold, it is not going to be emitting much IR (I think this is what the GP said when they said "generating"). Your typical deployment observation IR camera's won't be of much help in that case.

Re: James Webb is fully deployed

#445

Post by mywacaday »

devenvdev wrote: post #424
awb wrote: post #379

Earlier quoted context omitted.

The cost: 23 years and $10B The benefit: “JWST’s instruments are designed to make discoveries across the spectrum of astronomy — ranging from the worlds and mini-worlds in our own solar system to alien planets circling distant stars, from the supermassive black hole at the center of our own Milky Way galaxy to the edge of the observable universe.” ( https://www.geekwire.com/2021/high-cost-high-risk-high-hopes... ) Ex…

I don't understand why is it considered extreme cost. IIRC it's around $1/us citizen/year. For example the budget for keeping us safe from ourselves is much higher.

That's a great point, Makes me wonder what long term projects my own government have. Does anyone know of other inspiring long term projects in progress? The ITER fusion project is one that comes to mind.

Re: James Webb is fully deployed

#446

Post by simonh »

BurningFrog wrote: post #265
simonh wrote: post #262

Earlier quoted context omitted.

There is a list of specific questions JWST was built to answer. * What were the first stars and galaxies like? * How do stars come to form deep within a dusty nebula? * What are the atmospheres of Earth-sized worlds like, and do they contain signatures of life? * How far away do we need to look to see the pristine, pre-stellar Universe? * How did the early stars and galaxies assemble to give rise to what we have toda…

I know NASA has a reputation for bureaucracy, but I don't think it will be forbidden to use JWST for other purposes than those 5 questions? It is capable of being aimed at any point of the sky and show us things we've never seen before, is it not?

That is true, but it was designed specifically to perform certain tasks. It’s capable of much more, but those are essentially bonus stretch goals. Nobody is saying a second JWST would have no value, or couldn’t do useful science, that’s a gross mischaracterisation. There are diminishing returns, that’s all.

We all want more science, the question is what’s the best use of 3-4 Bn in extra funds. The real question is which other future telescopes and space missions would you cancel to get a second JWST?

Re: James Webb is fully deployed

#447

Post by DSMan195276 »

bmitc wrote: post #418
claaams wrote: post #415

Earlier quoted context omitted.

The point of the telescope is to capture IR light from space, if the telescope itself were generating IR light itself it would disrupt the sensor and data that it collects. Part of why its going to take so long for it to begin operating is that it needs to cool down to ultra cold temperatures before beginning operation.

Who said anything about generating infrared light? And I don't know what your last sentence is in reference to. Yes, it needs to cool down. Why is that relevant to this discussion other than what's already mentioned about that being a downside to operating cameras? From the article so people can just debate NASA's own reporting: > Although infrared or thermal-imaging cameras on the cold side could obviate the need fo…

I think that article is leaving out some of the other problems (which is understandable, it already covers plenty of downsides). The whole point of keeping the cold side cold is so that it doesn't emit any IR radiation (otherwise the JWST couldn't work). So by design it's "dark" to an IR or thermal camera in the same way it's dark to a visible light camera. Certainly you can build a camera to see it anyway (without extra lights), but the question then becomes how big that camera has to be, and I would assume it's way to big to be realistic.

Re: James Webb is fully deployed

#448

Post by t8972376723 »

jl6 wrote: post #192

More great news. Congratulations to all who have worked on the project. I understand the reasons for not putting a camera on or near the JWST, but I’m still a little sad that we’ll probably never get to see the thing in situ in all its operational glory. Maybe one day when it finally expires, we can launch a “sample return” mission to tow it back.

Maybe Hubble could be used to take images of it?

Re: James Webb is fully deployed

#449

Post by samus »

luxuryballs wrote: post #302
daveslash wrote: post #204

Earlier quoted context omitted.

RE>> "I understand the reasons for not putting a camera on or near the JWST" What are the reasons? I'm sorry ~ I'm ignorant on the topic, but I'd love to learn more. Why/what are the reasons?

Looks like there aren’t actually any good reasons. I’m actually kind of surprised that mere curiosity at what could have been seen wasn’t good enough.

Nothing could have been seen: on the bright side, a smudge of light. On the dark side, nothing. The mirror is currently at -172° C and further cooling down toward absolute zero temperature; even with infrared it's hard to see anything at this point.
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