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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

#161

Post by bumby »

GekkePrutser wrote: post #149
bumby wrote: post #141

Earlier quoted context omitted.

There's similar analogies here to the space shuttle. For the shuttle to get approved, it had to meet the demands of many masters. The fact that it had to meet DoD missions as well as NASA missions made it a bit of a boondoggle. Likewise, the JSF needed to meet the Marine Corps demands of VTOL to take the place of the AV8B. It's hard to remain focused when you have so many stakeholders. As the saying goes, a camel is…

The space shuttle wasn't as bad as its reputation though. Both accidents had organizational causes and were entirely avoidable. And its huge payload bay and the fact it was a mobile base allowed for the construction of the ISS. It just failed at reusability, it was more like refurbishability :) But many lessons have been learned from that.

I'm speaking more to the shuttle cost overruns, both in design and mission. I'd argue that the reusability aspect was central to the idea of a "shuttle" and if it failed at that, it missed its mark.

I agree 100% that there are organizational causes to past mishaps. As to whether or not it was avoidable...I tend to think they are rooted very much in human psychology and we think about risk. The same issues occur today within NASA (EVA 23 is a good example [1], despite the 'organizational' fixes put in place after Challenger and Columbia). Humans are really, really good at rationalizing the answer we emotionally want.

[1] https://www.nasa.gov/sites/default/files/files/Hansen_PressC...

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

#162

Post by auto »

7373737373 wrote: post #160
spaetzleesser wrote: post #139

When I look at project management for the small projects (1-20 people) I am working on I always wonder how projects of such a complexity are managed. It must be freakishly difficult to coordinate all the pieces. The people working on this will also have several stressful months ahead of them. From launch to full deployment so many things can go wrong and there is nothing that can be done when something fails.

I wonder the same for large (especially international) companies, government bureaucracies or other organizations. With thousands of employees and branches in different locations, it must be impossible to get a full understanding of the state of the system.

Same, makes you wonder how much slack/tolerance is built into these systems and organizations, and whether that comes in the form of manpower, process, etc. and whether or not it’s planned for, or just naturally evolves in large enough instances.

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

#163

Post by ultramegachurch »

nrdgrrrl wrote: post #73
ultramegachurch wrote: post #61

Earlier quoted context omitted.

Highly unlikely. That would require designing a new spacecraft from the ground up while also developing new robotics and operations technologies. I'd peg that mission at $300 - $500 million. NASA would almost certainty be better off documenting lessons learned and pursuing a new observatory.

They've spent almost 10 billion dollars on this telescope so far. What's another 0.5 billion for a repair mission?

That 0.5 billion (which to be clear, is a number I made up) won't guarantee that JWST will be fixed. The "fixer" spacecraft could end up failing itself. Or it could discover new problems that it's not equipped to handle.

Also, congress would be extremely critical of NASA if JWST fails. They would not be excited to shell out another $0.5 billion for a chance to fix it.

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

#164

Post by hypertele-Xii »

jcims wrote: post #75
lisper wrote: post #9

Earlier quoted context omitted.

I used to work at JPL, and I was there when the sky-crane (the system currently used to land rovers on Mars) was first proposed back in the late 90s. I remember thinking to myself, "That is the craziest idea I have ever heard, there is no way that could possibly work." But it did. Never bet against NASA engineers. Sure, they have the odd high-profile screwup, but on the whole they are shockingly competent.

Do you know if there is any test footage of that anywhere? That's, to me anyway, the second most amazing thing about the sky crane...that I can't find a single frame of it in operation on earth.

Earth physics are different from Mars physics. What works there wouldn't work here; can't just try it out and see if it works.

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

#165

Post by dylan604 »

jl6 wrote: post #54

If the JWST survives launch but has a subsequent mechanical problem that prevents it deploying properly (and it’s the kind of problem that would have been fixable on Hubble, using a shuttle mission) would it be feasible to mount a robotic rescue mission to chase it down and remote-hands it back to life? For less than the cost of just launching another JWST?

Seems to me it would be easier to design a craft to dock with it and bring back to an easier for humans to reach location. Then push it back out to where it needs to go. I'm sure there's some delta-v math to determine the fuel requirements, and I'm guessing it would also make a huge difference on how fast you wanted it back.

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

#166

Post by _greim_ »

bl5THJUSFXWy4ii wrote: post #95
mcbutterbunz wrote: post #78

Earlier quoted context omitted.

> I'd peg that mission at $300 - $500 million. If that was the cost for that mission, it would be worth it considering JWST cost about 20x that amount.

You are considering the entire cost of developing the JWST. Surely the cost of building another based on the finished design would be lower.

I wondered the same thing. I once read this commentary on project management (disguised as a StarWars fanfic)[1] which makes me pessimistic. However I'm in no way involved so I'd be curious to hear what someone more knowledgable thinks.

https://m.fanfiction.net/s/11685932/1/Instruments-of-Destruc...

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

#167

Post by justshowpost »

eganist wrote: post #148
justshowpost wrote: post #137

Earlier quoted context omitted.

Yes, if you prefer eye candy photos to public safety. By the way will James Webb wield a modern eye candy capable sensor? Not sure about that. There is few worth from remote sensing unreachable (even in theory) objects. Kepler already proved theoretized Goldilocks Zone rocky planets and, in general, provided a lot of data for non-field research (less exciting than Hubble photos indeed). Last, but not least, what's th…

I hate how shortsighted these comments tend to be, but I can understand them. The money for projects like this, largely due to the sensitive nature of it all, still ends up staying local to the governments funding the projects, which means a significant minority of it still gets recouped in taxes two or three degrees down, and the balance that can't be recouped still ends up funding colossal technological advances, e…

Well, all the tech advances brought by doing R&D of JWST happened already ~15 years ago and already are at the market. But its just the same thing as with R&D done for F-35. With notable exception F-35's R&D is still work in progress because of upgrades, while JWST will remain a piece of late 2000s tech to be taken out of the attic in early 2020.

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

#168

Post by hypertele-Xii »

slownews45 wrote: post #4

Does anyone remember the initial proposals for this. The cost was supposed to be $500M. At most something like $1B. Given this is standard govt contracting - I'm sure it's come out much higher.

If you thought estimating software projects was hard, try estimating a friggin space launch.

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

#169

Post by bumby »

Pokepokalypse wrote: post #155
Retric wrote: post #138

Earlier quoted context omitted.

Their designed for slightly different roles. The F-35’s R&D looks hard to justify vs simply having more F-22, but the F-35B can do verticals takeoff for example and the F-22 can’t. So, the real question is if the F-35’s should have had fewer versions and thus been more capable in it’s remaining roles.

F-22 theoretically can do a vertical take off as well. (not landing).

It has a thrust-to-weight ratio > 1, but it can't really take off vertically in the same sense as the AV8B or the JSF. The F22 still needs some appreciable runway so it's really a "short takeoff". I think the thrust vectoring maxes out around 25 degrees, where the JSF can be configured to 90 degrees.

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

#170

Post by bumby »

abz10 wrote: post #151
bumby wrote: post #140

Earlier quoted context omitted.

> Was the F-35 necessary for threat mitigation. No. Was it framed as the necessary for cost savings, yes. I think we're saying the same thing. The argument is, "Was the F22/F18/Fwhatever/weapon-system necessary for threat mitigation? Yes." With that said, if proponents of the F35 want to frame it as "threat reduction + cost savings" that's how they get the budget approved. But the point stands that without a threat,…

I don’t think it’s a great example of using existential threat for sales, when the whole thing was sold as a cost saving. Pretty much everyone at the time just wanted more F-22s. I was a technical advisor on the project.

>I don’t think it’s a great example of using existential threat for sales, when the whole thing was sold as a cost saving.

Again, if there is no threat (perceived or real), there is no need for a weapons system, period. Think of it this way, if there was a proposal for a cost savings for an anti-spacecraft/anti-asteroid system mounted to the JWST? I'm saying no, because there is no credible threat that would prevent. You need the threat first, in order for the cost savings of a program to have meaning if the basis of the program is threat mitigation.

>Pretty much everyone at the time just wanted more F-22s

Not really, unless you're only talking about a specific branch. Only the Air Force wanted F22s. As was stated by another commenter, the JSF was needed because it was because it fulfilled desires that other services had that the F22 does not provide.

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