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The James Webb Space Telescope has passed the final mission analysis review

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Re: The James Webb Space Telescope has passed the final mission analysis review

#221

Post by zabzonk »

bane wrote: post #191

It's my personal belief that these massive R&D space telescope programs are nearing their end. Computational approaches among multiple sensors, combined with good 'ol factory mass manufacturing powered by low-cost reusable launch technology allows for the money spent on one-shot programs like this to be spent and allocated in radical different ways. Instead of building one huge short life-span spacecraft, why not lau…

> Instead of building one huge short life-span spacecraft

Short life-span? How long has the Hubble been up there?

Re: The James Webb Space Telescope has passed the final mission analysis review

#222

Post by boardwaalk »

manquer wrote: post #210
gpt5 wrote: post #208

Earlier quoted context omitted.

Even if this computational photography vision is years away, JWST might still become obsolete quickly. SpaceX's Starship would be able carry telescopes than JWST as a single piece. This would dramatically simplify development and increase optical quality.

The challenges in building a mirror that size is enormous and take years. It is not only fairing size that is limiting

Wouldn't land-based telescopes already use larger mirrors than any space telescope?

Re: The James Webb Space Telescope has passed the final mission analysis review

#223

Post by wolverine876 »

Me1000 wrote: post #186
minikites wrote: post #70

Earlier quoted context omitted.

I wouldn't trust any payload on a SpaceX ship given their track record.

The Falcon 9 has had 126 missions so far and only 2 of those were failures. It's not a perfect record, but it's pretty decent. And presumably SpaceX has learned from those failures. Compare that to the Ariane 5 rockets (which will actually be launching the James Web Space Telescope) which has had 109 launches, and 5 of them ended in failure. I'm just going to assume you're referring to Starship's various explosions.…

> the Ariane 5 rockets (which will actually be launching the James Web Space Telescope) which has had 109 launches, and 5 of them ended in failure

I just read that they had one failure, though I can't find it. Does anyone have any reliable data (i.e., not Wikipedia)?

Re: The James Webb Space Telescope has passed the final mission analysis review

#224

Post by jasonwatkinspdx »

sydthrowaway wrote: post #200
jasonwatkinspdx wrote: post #178

Earlier quoted context omitted.

This is what Systems Engineers do. There's no magic bullet, but the basic process is lots and lots of documents. Much of what NASA does is published openly so you can get a feel for what some of these document types are like. The wiki page gives a decent summary. Building a model for the system is indeed a big part of the challenge. These days it's increasingly done as a fully detailed software simulation. The big CA…

Ugh, I can't deal with Systems Engineering. It's a whole lot of gobbledygook before getting to the crux of the problem. A software engineering analogue would be FizzBuzz Enterprise Edition https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpris...

I can understand not liking how bureaucratically onerous it is, but we don't really have a choice. It's imperfect but it's the only way we've found to manage highly complex large scale engineering projects. You certainly aren't going to build something like JWT with a just YOLO agile process unless you're literally willing to fail like 50 times before you get one right (aka the USSR approach to rockets).

The upside is automation is making it go smoother and be less burdensome, because simulated testing truly is high enough fidelity now it allows a bit more virtual trial and error in the process.

Re: The James Webb Space Telescope has passed the final mission analysis review

#225

Post by doctoboggan »

mongol wrote: post #53

What is it hoped this can see? Is there some specific hypothesis this telescope was built to confirm?

It should be able to detect the atmospheric makeup of expo planets (via spectroscopy during a transition). This will let scientists search for signs of life on other planets.

Re: The James Webb Space Telescope has passed the final mission analysis review

#226

Post by jasonwatkinspdx »

caconym_ wrote: post #217
jasonwatkinspdx wrote: post #103

Earlier quoted context omitted.

While I'm rooting for SpaceX with Starship, lets be clear: they're still trying to get hovering grain silo versions working. Meanwhile JWT is ready to go. If it's a race one side has already won rather emphatically.

Actually, they're well beyond the "grain silos" by now. They've successfully demonstrated the "bellyflop" landing maneuver from a terminal velocity fall, and now they're (credibly) trying to launch a full prototype Starship stack to orbit within the next few months. Wiki says JWST is planned to launch by this November, so I think there is a decent chance Starship beats it into space. That won't be a production-ready…

I know where SpaceX is. Elon does have a clear history of being overly optimistic about timelines.

There's a zero percent chance they'll have a vehicle ready by the JWT launch date that could launch it instead, even if they get to orbit by then.

This is not a race. As I said I'm a SpaceX fan, but I am not a fan of every single space topic being derailed by "but what about SpaceX?" as if they're the only company doing things meaningful in the industry. They're the super cool new kid on the block, but there's still a lot more out there that doesn't deserve to constantly be lampooned for not being SpaceX.

Re: The James Webb Space Telescope has passed the final mission analysis review

#227

Post by ckozlowski »

bumby wrote: post #121
phkahler wrote: post #113

Earlier quoted context omitted.

>> But I really don't know what all goes into making a space telescope so expensive currently. I think you already said it. The long life (high reliability) requirement, and I'll add the complexity of having it unfold. Both of those become non-issues if you build the telescope right into a space-X starship. There may be other issues with that, but the mirror wouldn't need to fold ;-)

Are you speaking to the reliability of the launch vehicle or of the satellite? The launch itself is typically not a primary cost driver of a satellite mission. Complexity may be, due to constraints of the fairings but the manufacturing and quality checks drive quite a bit of the cost

I think they mean reliability of the satellite. The JWST is going to be parked at a Lagrange point that's going to put it out of reach of most everything. At the time it was conceived, robotic servicing was even further off. A crewed mission was right out. Costs went far up in part because unlike Hubble, servicing was going to be virtually impossible.

Re: The James Webb Space Telescope has passed the final mission analysis review

#228

Post by zaarn »

boardwaalk wrote: post #222
manquer wrote: post #210

Earlier quoted context omitted.

The challenges in building a mirror that size is enormous and take years. It is not only fairing size that is limiting

Wouldn't land-based telescopes already use larger mirrors than any space telescope?

Can you launch those mirrors into space on a rocket without them turning into very fine glass dust? Cuz I bet a lot of mirrors in land-based telescopes would simply shatter or break on a launch.

Re: The James Webb Space Telescope has passed the final mission analysis review

#229

Post by caconym_ »

jasonwatkinspdx wrote: post #226
caconym_ wrote: post #217

Earlier quoted context omitted.

Actually, they're well beyond the "grain silos" by now. They've successfully demonstrated the "bellyflop" landing maneuver from a terminal velocity fall, and now they're (credibly) trying to launch a full prototype Starship stack to orbit within the next few months. Wiki says JWST is planned to launch by this November, so I think there is a decent chance Starship beats it into space. That won't be a production-ready…

I know where SpaceX is. Elon does have a clear history of being overly optimistic about timelines. There's a zero percent chance they'll have a vehicle ready by the JWT launch date that could launch it instead, even if they get to orbit by then. This is not a race. As I said I'm a SpaceX fan, but I am not a fan of every single space topic being derailed by "but what about SpaceX?" as if they're the only company doing…

> I know where SpaceX is.

I mean, Musk may be famous for his "optimistic" timelines, but you completely misrepresented their progress. "Still trying to get hovering grain silo versions working" is not remotely accurate.

That's the only point of my previous comment: give credit where it's due, as I said. I agree with most or all of the other things you've said in this subthread.

Re: The James Webb Space Telescope has passed the final mission analysis review

#230

Post by jagger27 »

whoisburbansky wrote: post #206
skhr0680 wrote: post #205

Earlier quoted context omitted.

Phone cameras show both the power and limits of computational photography. You can’t run away from physics forever.

Phone cameras don’t have multiple lenses working together that you can interpolate between to create a single giant virtual lens. The technique OP is referring to is already used for the largest ground based radio telescopes.

Well, a lot of phones do have multiple sensors and lenses. For example, the iPhone's computational depth effect uses multiple cameras for a single shot.
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