[HN Gopher] NASA's James Webb Space Telescope Launch Delayed to ... ___________________________________________________________________ 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 ___________________________________________________________________ (page generated 2021-09-08 23:00 UTC)