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James Webb is fully deployed

nasa.gov

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Re: James Webb is fully deployed

#361

Post by mattkrause »

Beldin wrote: post #184
WalterBright wrote: post #166

Earlier quoted context omitted.

> Yes, but the data has diminishing returns as well. I find that hard to believe considering there's literally a universe of things to look at. We find surprising things everywhere we look.

$3-5B would go a long way to a new Einstein telescope (ie. gravitational waves detector). It would likey allow for significant sensitivity increases in the existing ones. It could propel the National Ignition Facility or ITER forward. It could be used to build a new Arecibo. It could add an enormous amount of low-frequency telescopes - or other scopes for very large integrated scope arrays. I'd much rather broaden ou…

For reference, the entire NSF budget is about $8B (maaaybe $10B next year!).

Re: James Webb is fully deployed

#362

Post by [deleted] »

WalterBright wrote: post #319
porsupah wrote: post #281

Earlier quoted context omitted.

They did: "Unlike Hubble, Webb isn't designed to be fixed by astronauts. But it can be refueled robotically. Zurbuchen says that 'once this telescope is deployed, I'm going to put all the effort towards developing that technology, and so within the 10-year lifespan, we can go refuel it'" https://nitter.42l.fr/marinakoren/status/1474367236244750345... https://nitter.42l.fr/Dr_ThomasZ/status/1474398711505580032#...

The astronauts had some serious, unexpected difficulties fixing the Hubble in orbit, and had to improvise. I'm skeptical that blasting a fuel coupling into space, and then trying to figure out how to connect it to a robot, will end well.

[deleted]

Re: James Webb is fully deployed

#363

Post by idealmedtech »

Spare_account wrote: post #274
idealmedtech wrote: post #266

Earlier quoted context omitted.

How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!

>a truck sized craft at a few million light years? JWST is three light seconds from earth

Awful typo on my part! Definitely face palmed when I caught it.

Re: James Webb is fully deployed

#364

Post by terramex »

michaelwilson wrote: post #318
terramex wrote: post #82

Earlier quoted context omitted.

Pressure from solar wind will constantly put some torque onto telescope as its center of pressure is offset from center of mass. This torque will be counteracted by reaction wheels but they have maximum rotation speed and need to be unloaded using thrusters periodically.

Thus, the "Aft Momentum flap": https://www.jwst.nasa.gov/content/webbLaunch/deploymentExplo...

Momentum flap will bring average CoP closer to CoM but CoP will shift as JWST is rotated to point at different targets. Unwanted torque can be minimised by carefully choosing observations targets so it mostly cancels out but it cannot be done perfectly.

Re: James Webb is fully deployed

#365

Post by philderbeast »

samstave wrote: post #327
JshWright wrote: post #313

Earlier quoted context omitted.

All you would be able to see is the sunny side of the sun shield, none of the cool (both literally and figuratively) bits, which are all in darkness.

I have a few questions about extending a tethered "selfie bot" If you have a tethered camera which uses the tether as its power source which is out in front of the scope, wouldn't it be able to "stare" back at the Business Side of the mullet and stream the Party back to earth? Or does a teathered bot risk messing with the orbit of the scope? How much actual pull strength is requireed per kilo to re-orient something i…

even if its looking at the business side of the telescpe the sun sheild means there is no light there for it to be able to see anything.

its a case of your can't see it because there is no light, not because you dont have an angle of it (although that is also a chalange to overcome.

Re: James Webb is fully deployed

#366

Post by idealmedtech »

heavenlyblue wrote: post #271
idealmedtech wrote: post #266

Earlier quoted context omitted.

How can it make out galaxies at billions of light years away, but not a truck sized craft at a few million miles? I haven't done the math myself, so I'm certain one side of that equation is wrong, but that seems hard to believe!

It’s interesting that you are expressing an opinion about something that you could calculate in the same amount of time it took to write down that opinion.

It's been over a decade since my last astrophysics class, but I appreciate you being charitable about my assumed knowledge! I think if anything this thread shows:

1) how absolutely mindblowingly big space is

2) how bad humans really are at intuiting things at the scale of space

Re: James Webb is fully deployed

#367

Post by colechristensen »

samstave wrote: post #310
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.

Why dont we deploy a smaller sat in the same-ish orbit thats only job is to be the RING Doorbell for the JWST -- all it does is stream a live-stream back of the JWST -- if we can freaking deploy streams of Starlink (SKYNET) devices - we can certainly place tele-photo-capable sats that can then provide streaming video back of the things they are walking -- and they can FN relay off the starlink (SKYNET) devices...

Because it’s not interesting looking at a big sheet of tinfoil in space. It also would be quite likely that the two would run into each other.

And JWST is really far from earth, starlink would do nothing.

Re: James Webb is fully deployed

#368

Post by colechristensen »

bmitc wrote: post #101
dgrin91 wrote: post #23

One of the big numbers that been thrown around is that JWST has 344 single points of failure in its mission. Now that deployment has been completed, is there somewhere that lists how many of those points we have passed?

Can anyone elaborate on these single points of failures? For example, are they actually single points of failure? Or is it a bit of exaggeration for marketing purposes (a bit of under promise, over deliver)?

It’s probably an internal list of serious things that could go wrong. There’s a lot of bike shed discussion here about what a “single point of failure” should include.

Re: James Webb is fully deployed

#369

Post by mturmon »

guerrilla wrote: post #167
WalterBright wrote: post #75

Since 90% of the cost is probably in R+D of the telescope, one could build and deploy another for another 10%. Why isn't this done? Why is every space telescope completely unique?

I wish there were a FAQ. This comes up every single time there's a thread about Webb on HN. Search previous posts. You'll see a hundred answers to your question, some of them well researched.

This is accurate, and unfortunately the questioner is going through all the threads repeating naive objections to the legit answers offered by people familiar with aerospace. I know the guy who led the assembly of the JWST/MIRI cryocooler, which was one of a handful of high-risk items on the spacecraft, and all of his team’s time was taken up with assembly, build, integration, and test, not just abstract design. I’ve explained this kind of thing in past threads, but it’s tiresome!

Re: James Webb is fully deployed

#370

Post by [deleted] »

WalterBright wrote: post #337
tokai wrote: post #219

Earlier quoted context omitted.

Machine shop experience is not related project cost estimations.

Sorry, I'm not buying that. But that notion might be one reason why government projects cost so much. I've taken apart cars many times. I know when I'm being fed a baloney sandwich when taking my car in for service, and use that to pare down the estimate sometimes as much as 50%. (For all the women who rightly complain about being scammed by auto mechanics, I can vouch for them doing their best to scam me about 75% o…

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