[HN Gopher] NASA's James Webb Space Telescope Launch Delayed to ...
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NASA's James Webb Space Telescope Launch Delayed to December
Author : asmithmd1
Score : 45 points
Date : 2021-09-08 21:04 UTC (1 hours ago)
(HTM) web link (www.space.com)
(TXT) w3m dump (www.space.com)
| avmich wrote:
| Why it's not made serviceable? Or at least able to be serviced,
| with non-herculean efforts? Manned missions to L2 would both
| maintain the truly unique device and move forward the manned
| space capabilities and experience. It's just - what? - four time
| farther than the Moon?
| sp332 wrote:
| It was hard enough to make it small and lightweight enough to
| get out there, with epoxy instead of bolts for example.
| Nekhrimah wrote:
| At the time the design was locked in, there was nothing even
| planned that would be capable of supporting a crewed servicing
| mission. They have however included a grapple bar so that there
| is something to connect to should there be something in the
| future. SpaceX's Starship is the most likely vehicle at this
| stage, but that is still substantial development away from
| being capable of a James Webb servicing mission.
| knappe wrote:
| How would we get there? There is no current vehicle that could
| be used to service anything at L2.
| sparker72678 wrote:
| One reason (of many) is that when the telescope was designed
| there was no way to know if we'd have capability to send anyone
| (or anything) to service it.
|
| Even today we don't have a proven platform that could pull off
| a manned mission to L2, let alone a mission that would then fix
| an insanely complex telescope in-situ. (There are a few that
| could _try_ , but no one's done it.)
| cycomanic wrote:
| Sending a manned mission to L2 for repair just doesn't make
| sense. You might as well just build a new telescope and send it
| out again, that probably would be cheaper. Just look at the
| massive effort that it took to go to the moon. Sure we are now
| more advanced, but if it was easy to go there now Elon would've
| already flown. As you said L2 is 4 times further, and you need
| to stop and restart at each point.
| ekrebs wrote:
| They need a firm launch date because of the cascading research
| windows already allocated, but there are 344 single points of
| failure, and it will be virtually impossible to fixed once
| launched. I'm terribly excited for the advancements this
| telescope will bring, but I'm very nervous about the launch and
| deployment.
| LeifCarrotson wrote:
| The good news is that the trajectory of timeline slip is less
| than one week per week, and if that holds true, the two will
| eventually rendezvous.
|
| In 1996, it was estimated for 2007, fast forwarding a bit to
| 2018, it slipped one year from an estimated launch in 2020 to
| 2021, in 2020 it slipped from March 2021 to July, by January 2021
| it slipped to October 31st, and it's been known since June, 14
| weeks ago, that it wasn't likely to meet that date.
|
| At this rate, I estimate the current date will intercept the
| target date in early 2022.
| nsxwolf wrote:
| I cannot foresee a timeline where it does not explode on the
| pad.
| khuey wrote:
| Most of the time and money was spent on design. If it blows
| up they should be able to build a second one for a fraction
| of the time/cost of the first one.
| mmazing wrote:
| I hope you are incorrect. I will be extremely sad if this
| mission is not successful.
| chroem- wrote:
| Although tragic, it would be a fitting end to this
| boondoggle of a project. JWST was originally marketed as a
| quick, cheap win for NASA, but it turned into the polar
| opposite of that.
| asmithmd1 wrote:
| My thinking is the solar shield gets stuck/torn on
| deployment. Among the numerous bad decisions, they have no
| cameras watching the deployment
| perihelions wrote:
| > _" trajectory of timeline slip is less than one week per
| week, and if that holds true, the two will eventually
| rendezvous."_
|
| Not mathematically certain. If the timeline slip is a sequence
| like [1-1/2^k]_{k=1...} = {1/2 week, 3/4 weeks, 7/8 weeks,
| 15/16 weeks...}, then it's possible the project timeline could
| diverge forever. (This is just a restatement of Zeno's
| paradox).
| TeMPOraL wrote:
| The act of delaying launch takes non-zero amount of time in
| the real world, so at some point the slippage fraction gets
| so small that the launch will happen while being about to be
| rescheduled.
| perihelions wrote:
| You just keep observing the quantum superposition of
| launch/no-launch, using increasingly powerful lasers.
| Covzire wrote:
| Why does the launch date keep slipping? I've been looking
| forward to this launch for a very long time and I'm getting
| pretty irked at the teams sending this up, to the point where
| even if they are completely successful I hope they don't get
| put on another big project like this again. Hopefully the
| delays have been because it's a lot harder to send this to L2
| successfully than anyone thought or could have known, and now
| we do.
| sp332 wrote:
| Lately, Covid has been the holdup.
| https://wwwnc.cdc.gov/travel/notices/covid-4/coronavirus-
| fre...
| dzhiurgis wrote:
| Had my reddit reminder trigger back in July. I think I've set
| it up like 6 years ago. Amazed it actually worked.
| slownews45 wrote:
| Damn - these are full time employment deals for folks. 25 years
| on one project!
|
| Question - they have a ton of shielding for solar radiation -
| can they not locate this thing in a shadow area somewhere?
| perihelions wrote:
| Related:
|
| https://news.ycombinator.com/item?id=10462349 ( _" NASA's
| last original_ Voyager _engineer retires at 80 "_)
| perihelions wrote:
| There aren't any permanent shadows in space. Every orbit goes
| "around" eventually -- and there's no configuration where
| some combination of objects works to permanently shadow you.
|
| (A technical exception is a planetary solar L2 Lagrange point
| [0], *if* it would occur close enough to a planet to be
| totally eclipsed. But that doesn't happen (AFAIK) -- they're
| generally far enough away that while the planet is always in
| front of the sun, the planet's disk is much smaller than the
| solar disk).
|
| With cryogenic cooling, you have an even more difficult
| challenge: the light of a _planet 's infrared radiation
| emission_ is something you also have to shield. That's a
| major reason JWST (and similar telescopes) go to solar L2:
| the sunshield not only blocks out the sun -- it
| simultaneously blocks out the sun _and_ the Earth. That 's
| the unique advantage of the solar L2 point.
|
| [0] https://en.wikipedia.org/wiki/Lagrange_point
| zardo wrote:
| Possibly, but they couldn't power it by attaching solar
| panels.
| causality0 wrote:
| Being in a shadow area would mean it would be in orbit of
| something, and at best it would be in shadow 50% of the time
| and still need the same amount of shielding for daylight
| operations. Being in orbit would also mean its position would
| be much less stable than it will be at the L2 point.
| tshaddox wrote:
| > The good news is that the trajectory of timeline slip is less
| than one week per week, and if that holds true, the two will
| eventually rendezvous.
|
| Not if the timeline slips such that at each slip the delta
| between the current time and the launch time decreases by 50%.
| feoren wrote:
| It still works in that case, actually; you just have to pass
| through a singularity where the timeline is delayed
| infinitely many times, but the total amount of each of those
| infinite delays is finite. 1/2 + 1/4 + 1/8 + 1/16 + 1/32 +
| ... = 1.
| irrelative wrote:
| See also: https://xkcd.com/2014
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