[HN Gopher] Webb flies Ariane 5: watch the launch live on 25 Dec... ___________________________________________________________________ Webb flies Ariane 5: watch the launch live on 25 December Author : cos2pi Score : 198 points Date : 2021-12-24 14:34 UTC (8 hours ago) (HTM) web link (www.esa.int) (TXT) w3m dump (www.esa.int) | keewee7 wrote: | How much did NASA, ESA and CSA each contribute to this project? | jacquesm wrote: | From the JWST wikipedia page: | | "In the 2005 re-plan, the life-cycle cost of the project was | estimated at US$4.5 billion. This comprised approximately | US$3.5 billion for design, development, launch and | commissioning, and approximately US$1.0 billion for ten years | of operations.[18] ESA is contributing about EUR300 million, | including the launch.[84] The Canadian Space Agency pledged $39 | million Canadian in 2007[85] and in 2012 delivered its | contributions in equipment to point the telescope and detect | atmospheric conditions on distant planets." | | https://en.wikipedia.org/wiki/James_Webb_Space_Telescope | gautamcgoel wrote: | Those numbers are completely obsolete; the final price tag | was over $10B. | geenew wrote: | The CSA is contributing staff to operations as well, afaik. | | A more recent source says this (found through wikipedia). | Values all appear to be up to launch, and do not include | operations. NASA: 8,800m ESA : 850m | CSA : 200m ------------ All : 9,850m | | (No epoch given to dollars; presumably they are 2021 USD) | | _" Gunther Hasinger, ESA director of science, estimated | that Europe's contributions to JWST, in the form of | instruments and the Ariane 5 launch, to be about 700 | million euros ($850 million), roughly the same as an ESA | "M-class" science mission. | | Gilles Leclerc, director general for space exploration at | the Canadian Space Agency, said Canada's contribution of an | instrument and fine guidance sensors cost the agency about | $200 million Canadian ($165 million) over 20 years. "This | is an investment in discoveries of the universe," he said. | | NASA now estimates it will spend $8.8 billion on JWST | through the spacecraft's launch."_[1][2] | | Those numbers line up with a summary the Planetary Society | put out.[3] That source includes info on the operations | cost, at least for the US: | | " _The James Webb Space Telescope (JWST) is expected to | cost NASA $9.7 billion over 24 years. Of that amount, $8.8 | billion was spent on spacecraft development between 2003 | and 2021; $861 million is planned to support five years of | operations. Adjusted for inflation to 2020 dollars, the | lifetime cost to NASA will be approximately $10.8 billion. | | That is only NASA's portion. The European Space Agency | provided the Ariane 5 launch vehicle and two of the four | science instruments for an estimated cost of EUR700 | million. The Canadian Space Agency contributed sensors and | scientific instrumentation, which cost approximately CA$200 | million._" | | All three agencies will supply staff to support operations, | which I guess makes sense since they've all contributed | different instruments.[4] | | [1] https://spacenews.com/jwst-launch-slips-to-november/ | | [2] https://en.wikipedia.org/wiki/James_Webb_Space_Telescop | e#Cos... | | [3] https://www.planetary.org/articles/cost-of-the-jwst | | [4] https://en.wikipedia.org/wiki/James_Webb_Space_Telescop | e#Par... | jacquesm wrote: | Then maybe you should update that wikipedia page. | kitd wrote: | All the best to everyone working on this tomorrow. Hope you get | some suitably generous TOIL in January. | _joel wrote: | A fantastic Christmas treat, best of luck to all the teams | involved :) | gfodor wrote: | Interesting they found a way to add a hidden risk variable to the | launch, by sending it up on a day people are having to choose to | not be with their families. Have a bad feeling about this :/ | [deleted] | daenney wrote: | "They" didn't find anything. It wasn't originally planned for | tomorrow. The weather found a way. There's only so much wiggle | room and launch windows. | gfodor wrote: | I didn't imply they did it on purpose. The they here is in | the spirit of Murphy's Law. Seriously: launching on Christmas | seems like a bad and unnecessary source of entropy. | rrss wrote: | > It wasn't originally planned for tomorrow | | Right, it was originally planned for 2007. | | It is sorta funny that after 14 years of delays they picked | the week of Christmas. | mrtksn wrote: | They didn't pick that either, it was supposed to launch | earlier but a clamp broke down when attaching the telescope | to the rocket sending vibrations all over it and and as a | result they had to inspect for damages, further delaying | the launch. Then the weather wasn't good and delayed once | more. | rrss wrote: | They did though. It was delayed, they chose to delay it | from October to December 18 to December 22 to Christmas | instead of like the first week of January or whatever. | | It's not like this thing is launching to Mars and they'd | have to wait a couple years if they miss this week - it | could launch on 210 days of each year. | | https://jwst.nasa.gov/content/about/faqs/faq.html#launchW | ind... | | I don't mind at all, I just think it's a bit funny. | myself248 wrote: | what's funny about it? You think there's anyone working | on this project who isn't super excited to see it go up | on Christmas? | | No better gift than a successful launch. The folks | working on preparations overnight surely see themselves | as Santa's Elves in some fashion. | gfodor wrote: | Exactly - you highlight the problem. Launching on | Christmas introduces unique situational entropy. They | should do it later. | foobarian wrote: | Decades of meticulous planning and they couldn't give their teams | a day off on Christmas? Of course it could be that consensus was | this beats any other kind of activity that day in which case fair | enough. :-) | malermeister wrote: | Lots of European countries celebrate Christmas Evening (Dec 24) | more than Christmas Day (Dec 25). | CoastalCoder wrote: | I wish for our Canadian friends that the telescope unfurls on | Boxing Day. | Ostrogodsky wrote: | Yeah, 25th is the day to nurse the hangover | jpgvm wrote: | I think spending Christmas wringing your hands unsure if your | $10B decades-in-development baby is going to make it to orbit | sounds incredibly stressful... | | It's going to be awesome for us to watch but I feel for all the | folks that worked on this. | ajross wrote: | FWIW: given the extraordinarily complicated mechanical | design, merely reaching orbit is the "easy part". The real | imagined disasters won't happen until the mirrors assemble. | mortenjorck wrote: | True, though it's also worth considering that Webb is going | far beyond "orbit" as we generally think of it. I don't | know how much has been launched all the way out to L2 | before, but it's probably an order of magnitude less than | what's in Earth orbit. | krisoft wrote: | > I don't know how much has been launched all the way out | to L2 before... | | There is a handy list on wikipedia: https://en.wikipedia. | org/wiki/List_of_objects_at_Lagrange_po... | | Your intuition is quite right, there is way less | satellites parked around L2 than in low earth orbit for | example. | | But that doesn't really pose too big of a challenges in | itself. It is of course far, both distance wise and | energetically. | | The main complication often mentioned is if something is | wrong with the telescope it makes it very unlikely that a | crew can visit it to fix it. The way for example how they | repaired Hubble is unlikely to happen with Webb. | ajross wrote: | Meh, but there's nothing to hit in space. The energy | required to reach a routine geosynchronous orbit is | already ~85% of escape velocity. The added boost is | minimally more dangerous and the trip is just empty | hours. "Time" does kill spacecraft, but not often. | | The Webb self-assembly is absolutely where the scary bits | lurk. | jpgvm wrote: | Yeah valid. Though the whole "hurtling upwards on top of | a bomb" part is still definitely scary in it's own right. | argiopetech wrote: | Particularly given the launch record of the Ariane 5 | platform. I did some quick research, and no modern launch | platform has as high a mission failure rate (4.5%.) The | Delta family comes close at 4.4%, but that's a 50yr | launch history. The Delta 4 iteration has had no | failures. | jacquesm wrote: | As I wrote elsewhere, the bulk of those failures were in | the first 15 launches, after that it was a very long | string of one success after another with one partial | failure in 2018. | Symmetry wrote: | The Ariane 5 is batting 106 for 111 which is pretty good | odds and perfectly respectable for a heavy lift vehicle... | but not so much so that I don't wish it was launching on an | Atlas 5 instead. | jacquesm wrote: | Four of those were in the first 15, the last recent one | was in 2018, and was a partial failure. | GuB-42 wrote: | Ariane 5 had some early problems, the first failure even | became a case study in critical software development. But | it had only had one partial failure after the 17th | launch: the payload was launched to the wrong orbit | because the wrong coordinates were put in the computer. A | huge QA problem but not the fault of the launcher which | did exactly as told. | | Now, both Ariane 5 and Atlas 5 are extremely reliable, | mature rockets. | _ph_ wrote: | Well, according to the original planning it should have | launched before Christmas. It was only the weather delaying it | by one day. I guess once they were ready for the launch, they | want to avoid to delay it any longer than needed. Not sure, how | long the rocket can be "stored" in launch-ready state before it | has to be serviced again. | sp332 wrote: | It was scheduled for Wednesday and then postponed for bad | weather. | [deleted] | jacquesm wrote: | If you start planning your rocket launches around religious | holidays then that is going to be a bit of a problem, there are | just too many of them: | | https://nationaltoday.com/religious-holidays/ | rrss wrote: | How about planning around the single most celebrated holiday | in the US, religious or not: https://en.m.wikipedia.org/wiki/ | Public_holidays_in_the_Unite... | jacquesm wrote: | Ariane 5 is a European effort, not a US effort, it will | launch from French Guyana, not from the US. | | https://en.wikipedia.org/wiki/Ariane_5 | rrss wrote: | Cool. | | Webb will be monitored and operated by NASA in Maryland. | | https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescop | e#T... | | https://en.m.wikipedia.org/wiki/Space_Telescope_Science_I | nst... | jacquesm wrote: | I really don't get your fixation about this: the people | involved are all most likely extremely happy to see their | creation fly and to have Christmas take a backseat to | that. | | Let's just hope it all goes well, this is one of the most | complex space endeavors we've ever tried, and if it fails | it will have many negative long term implications. | rrss wrote: | I did not get your real or feigned ignorance that | Christmas is a much more significant holiday to the vast | majority of the people involved than the Feast of the | Ass. | | I also hope all goes well. Cheers. | jacquesm wrote: | I couldn't care less about Christmas, but I _do_ care | about the JWST, and I can 't wait for first light. | soperj wrote: | If you worked on something since 1996, do you think you | would give two flying figs what day it launches on? | rrss wrote: | my personal preference is irrelevant. my comment was | regarding whether it is tractable to plan around | Christmas, or unreasonable because there are too many | holidays of comparable significance. | desmosxxx wrote: | Too many holidays might be a factor but I really doubt | it's a large one. The bigger reason is you just don't | delay a 20 year $10billion project for any holiday. | | Some of the grunts might be disappointed but having | worked on way less important things that were launched on | holidays, I can guarantee anyone significantly involved | in the project is just happy to see it get off the ground | no matter what day. You have a good window for launch, | you take it | [deleted] | furyofantares wrote: | Newton's birthday sounds like the perfect day for a rocket | launch to me | kibwen wrote: | Since Isaac Newton was actually born extremely prematurely, | at less than 30 weeks of pregnancy, maybe he was the one | rushing to match the date of the JWST launch. :P | makira wrote: | He was born January 4th, using modern calendars. | | https://www.britannica.com/biography/Isaac-Newton | furyofantares wrote: | Oh cool, I get to celebrate his birthday twice per year | now. That said, strangely enough, if the calendar changed | after my death and people were still celebrating my | birthday, I'd expect people to celebrate the day on the | calendar I used rather than the accurate day. | ape4 wrote: | For people in North America 12:20 GMT is... | 4:20 am PST 7:20 am EST | | Get up before the children ;) | jessriedel wrote: | Are there alternative streams that anyone here would recommend? | The more technical, the better. | drunkonvinyl wrote: | The original title "Webb flies Ariane 5: watch the launch live" | has a nice ring to it. Here goes! | notjustanymike wrote: | And here I am, feeling nervous about a production web deployment. | Sosh101 wrote: | Personally I hate launching anything around the Christmas period. | mulcahey wrote: | LaunchHN: JWST on Christmas | Ankaios wrote: | It's humanity's self-unwrapping Christmas present. | Mesisio wrote: | Love it :D | meepmorp wrote: | Hopefully. | amichail wrote: | Why isn't SpaceX doing this? | varjag wrote: | The project and the choice of contractors predates SpaceX. | ddalex wrote: | SpaceX wasn't a thing when the project constraints were | defined. | NikolaeVarius wrote: | Because the contracts were made before SpaceX was deemed | reliable. | adventured wrote: | The launch partner/platform wasn't chosen recently and it's | part of what ESA is providing as a partner in the program. | | "In exchange for full partnership, representation and access to | the observatory for its astronomers, ESA is providing the | NIRSpec instrument, the Optical Bench Assembly of the MIRI | instrument, an Ariane 5 ECA launcher, and manpower to support | operations. The CSA will provide the Fine Guidance Sensor and | the Near-Infrared Imager Slitless Spectrograph plus manpower to | support operations." | | https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Par... | khuey wrote: | "not recently" is underselling it a bit. ESA agreed to launch | it before Falcon 9 (let alone the Heavy version) had ever | flown. | rrss wrote: | It looks like it was even before Falcon 1's first success. | [deleted] | _fizz_buzz_ wrote: | Ariana 5 can transport a larger/heavier payload than Space X | rockets. And even then the telescope has to be folded up in | this really complicated way. | jcfrei wrote: | A fair comparison would be to Falcon Heavy (Ariane 5 uses | boosters as well) which has about twice the payload capacity. | Just doesn't yet have the launch history required for such an | important payload. | sprucely wrote: | Contracts or momentum? Haven't looked at actual dates, but my | guess is that this project was established long before SpaceX | was a viable option. | fnord77 wrote: | ariane 5 has had 111 launches. Falcon heavy has had 3. | | the falcon heavy probably didn't even exist when they were | drawing up the contracts | sidkshatriya wrote: | I think Falcon heavy is not needed. Webb's weight is ~6200 | kg. Falcon 9 is 8300 kg to GTO (Geostationary transfer | orbit). This leaves about ~2000 kg fuel equivalent to spare | which should be more than enough for the special location | Webb is aiming for. | | But yes, the contract for the webb launch was probably locked | a very long time ago. | | (Though it's also possible that Falcon 9's fairing wont be | able to accommodate Webb) | ur-whale wrote: | > Why isn't SpaceX doing this? | | Reliability (as in: established track record). | | Although, if Ariane decides to explode tomorrow, this comment | will look ... odd. | rrss wrote: | Important to note that the agreement was made in 2007, so | reliability as a factor would be reliability as assessed in | 2007, not 2021. | | I think that in 2021, Falcon 9 's track record arguably | suggests it is more reliable than Ariane 5, but it doesn't | matter because the Falcon fairing is too small for JWST. | InTheArena wrote: | This has to be launched by Ariane - it's constraints are | tightly bound to what that platform can do, and it's fairing | size. Ariane is optimized for GEO insertion, while Falcon is | optimized for LEO orbits. You could have used a Falcon, but a | payload like this was actually built around the rocket's | capability, and this was designed prior to Falcon being a | thing. | | All that said it's worth nothing that SpaceX's flight success | rate is 98.5 (135/137), while Ariane V's is 95.5 percent | (106/111). | | The really gobsmaking thing about that is that this is that | SpaceX's rate is over 11 years, while Ariane's is over 25 | years. | | It's time to stop thinking of SpaceX as the plucky, | untrustworthy startup. | | In the future space telescopes like this really need to be | built in LEO, and then boosted to Lagrange points. The number | of failure modes beyond the typical rocket / stage / fairing, | secondary burns that the folding mechanism and the lack of a | ability to test a ton of new technology in zero-g orbit makes | this far more likely to fail then anyone is comfortable with, | given the overall cost to this. | unethical_ban wrote: | Does anyone really think of SpaceX as a scrappy startup? | You seem to recognize that this mission was designed and | set in stone well before SpaceX was established. | | I don't know if JWST needed vertical assembly, but I recall | that some spy satellites in the past have had to be | launched on Atlas/Delta because they need to be assembled | on the rocket vertically (vs. being rolled out to the | launchpad horizontally). | architravesty wrote: | Falcon 9 has a better track record than Ariane 5 at this | point, but SpaceX wasn't really a thing at the time these | contracts were signed. | adgjlsfhk1 wrote: | also falcon heavy would be required which only has had 3 | launches (all success though) | guerrilla wrote: | Countdown with links to livestream and blog here: | https://www.jwst.nasa.gov/content/webbLaunch/countdown.html | ourmandave wrote: | If you want to skip the Super Bowl pre-game, the actual launch | window starts at 7:20 am EST (12:20 UTC) and lasts for 31 | minutes. | | It can launch anytime during that window. | neals wrote: | I can't watch this. So many years and so many man-hours riding on | top of a rocket is to much for me. | C19is20 wrote: | Similar. But more because I can't believe they didn't build two | - for redundancy. | anotheryou wrote: | I wonder what time and cost a rebuild would have. Maybe half | the original development costs? | dimtion wrote: | I do have a question about JWST that I wasn't able to find a fine | answer in other forums. | | A lot of people and engineers are saying that the JWST is a | marvel of engineering, with truly inovative technical solutions | and a giant step up compared to Hubble Telescope. And it does | seems like so! | | However, I'm always baffled how everyone seems proud that the | telescope has something like 200 SPOF during deployment, and if | even one of them fails the whole mission could fail. | | I know that each step has probably been throughoutly tested, and | that the acceptable probability of failure of each one of those | steps has been deemed acceptable. But I'm still surprised that | people are proudly conflating excellent engineering with a design | that has a large number of spofs. | | In my domain this would be considered as a terrible design (aka | "hope is not a strategy"), even given the constraints of mass and | volume that such project incur: 200 hundred low probability | events, chained, can get in the realm of possible. | | I can't imagine JSWT team doing "bad engineering", so I'm sure | I'm missing a piece. Is it only PR that underline this aspect? Is | JWST as brittle as the news want to make us think? Or are there | technical reasons or acceptable failure modes that gives | confidence that those steps are not as critical as the news let | us people know? | jacquesm wrote: | Unlike say, the Apollo program, which had a guaranteed | successful outcome? | | The thing to realize is that these are some of the hardest | things humanity has tried their hand on and _if_ it all works | that 's a great thing for all of us, if it fails we will learn | something and we'll go back to the drawing board (but we won't | have a JWST and that's a significant loss, besides the obvious | future calls of 'look at what happened to JWST' which will no | doubt have negative impact on finding funding for future space | missions). | | Also, I think you're mistaken about people being 'proud about | the 200 SPOFs', if they could have made it one less they | certainly would have because everybody involved wants this to | succeed. Think of these as the ones that they simply could not | get rid of no matter how hard they tried. | twistedpair wrote: | > Unlike say, the Apollo program, which had a guaranteed | successful outcome? | | Apollo was wildly dangerous. Apollo 1 killed the whole crew. | The contemporary calculated failure odds for a Saturn V | launch were 1/8. Compare that to the current Dragon 2 | projected LOC risk of 1/276 [1]. | | [1] https://en.wikipedia.org/wiki/Crew_Dragon_Demo-2#:~:text= | NAS.... | Stratoscope wrote: | I think GP was being sarcastic. | jacquesm wrote: | Absolutely. Those guys were laying their lives on the | line with every launch. | redis_mlc wrote: | WJW wrote: | Perhaps it's a case of "we're proud that we got it all the | way down to _only_ 200 SPOFs in the final design, the earlier | designs were way worse ". | jacquesm wrote: | There is a fair chance of that, actually. If you start | enumerating the ones that are obvious even to lay people ( | _one_ rocket, _one_ satellite, _one_ set of mirrors and so | on) then this is probably an extremely impressive low | number. | shmageggy wrote: | I've been binging JWST content and definitely recall John | Mayer saying in at least one interview that 344 single | points of failure was as low as they could get it. And I | can believe it. If you watch some of the more detailed | interviews, he always stresses how every design choice | was heavily labored over and reviewed. | jacquesm wrote: | It's an absolutely amazing effort, from the design | through all of the problems they had to deal with along | the way to seeing it sit there on top of that booster. A | few months from now we could be in a completely new era | of astronomy. | darknavi wrote: | > However, I'm always baffled how everyone seems proud that the | telescope has something like 200 SPOF during deployment, and if | even one of them fails the whole mission could fail. | | I'm not sure I've seen anyone who is _proud_ of it, lots of | people are just setting expectations. Probably due to the | similarities with Hubble (although JWST can self-align it's | mirrors!). | | It also might be posturing to show how well the thing is built. | Space is hard, like really hard, and these agencies keep | knocking it out of the park. | harshreality wrote: | I think all the SPOF talk is expectation management in case it | fails. It's part space telescope mission, part engineering | challenge. Even if the space telescope part fails, the | engineering effort that's gone into it means something. | | They must've calculated that the overall chance of success, and | they have a target, and they met their target. Unfortunately, | tests and theoretical modelling have a tendency to not exactly | replicate a space environment (or any true production | environment), nobody's perfect at anticipating everything, and | management has ways of manipulating engineering estimates. | | The Space Review [1] quotes NASA as saying there are 344 SPOF. | They talk mainly about the sun shield, so that's probably the | biggest risk, but consider all of them as about equal... | | If each SPOF has a 0.1% chance of failure, net success rate is | only 71%. Presumably most of the estimated failure | probabilities are less than that, and the sun shield--which | probably comprises many of the SPOFs--averages (far?) more than | 0.1% per SPOF, because everyone seems to be particularly | worried about that working. | | I wonder what that figure is. Has it been published anywhere? | Dear NASA and ESA, what do your engineers say about overall | chance of failure? | | [1] https://www.thespacereview.com/article/4303/1 | sgt101 wrote: | It has to fit in the fareing, survive launch stress and | vibration, fly further than the moon and it has to weigh 6000 | kgs +including fuel. If it works it will be one of the greatest | engineering feats of history. | nharada wrote: | I'm guessing it's a case where all the various extreme | requirements simply do not allow for redundancy in the places | the engineers would prefer to have it. The options are likely | (1) okay performance with a lower chance of failure or (2) | extreme performance with a higher chance of failure. | nkrisc wrote: | > However, I'm always baffled how everyone seems proud that the | telescope has something like 200 SPOF during deployment, and if | even one of them fails the whole mission could fail. | | Genuinely curious: how would you have achieved the mission | goals with fewer SPOF? | GekkePrutser wrote: | Every kilo launched costs a proverbial and probably nearly | literal tonne of fuel so things are not as simple as that. | | It's also has to fit on the rocket hence the once off folding | mechanism. And after deploying it has to be perfectly aligned | (remember the Hubble with its slightly off mirror) | | I think having redundancy for everything would just not make | for a launchable spacecraft. | throw0101a wrote: | > _Is JWST as brittle as the news want to make us think? Or are | there technical reasons or acceptable failure modes that gives | confidence that those steps are not as critical as the news let | us people know?_ | | There is no room for redundancy in many aspects of the design, | unlike, say a Boeing 777 or Airbus A350. | | How can you have a redundant heat shield, or primary mirror | (two parts of which swing)? I'm sure some computer systems have | redundancy and perhaps comms. | | But like with a helicopter: how can you have redundancy in the | tail rotor? | | So with the JWST: there's no way around many SPOFs. | GekkePrutser wrote: | Does this have a heat shield? It won't re-enter right? It's | far too far away for that. | krisoft wrote: | Not the kind of heat shield you would use to re-enter. | | The telescope is designed to image very faint sources of | infrared light. The problem is that everything (including | the telescope itself) glows in infrared. The hotter things | are the more infrared they emit. Because of this you want | to keep the instrument as cold as possible. (You do this | because you don't want to drown the faint sources by the | glow of the telescope itself.) | | Now of course there are parts which has to be "hot". At | least relatively to the very cold instruments. The solar | panels are heated by the sun, the transmission electronics | and the processing turns electricity into heat. The | positioning thrusters burn chemicals which makes them hot. | | Because of this they designed the spacecraft with two | sides, a cold one for the instrument and a hot one for | everything else. They even choose the orbit cleverly so | they can keep the sun and the earth and the moon always on | the hot side of the vehicle. | | And then you have this problem that you have to make sure | that the hot side won't warm up your cold side. This is | where the heat shield comes into play. Sometimes it is also | called a sun shield since the sun is the main source of | heat for it to shield against of course, but it also | shields the instrument from the heat of the hot side | equipments. | | Structurally it is a 5 layer lassagne. They just replaced | the pasta with metalized kapton tape and the sauce with the | vacuum of space. It is about the size of a tennis court, | launches folded up and will un-fold in space. Hopefully. :) | akiselev wrote: | It's actually a sunshield [1] | | [1] | https://webb.nasa.gov/content/observatory/sunshield.html | mastax wrote: | Better helicopter example is the Jesus Nut. | Teknoman117 wrote: | "Because it it comes off that's who you're seeing next" | jacquesm wrote: | Regarding that helicopter example: | | https://verticalmag.com/news/bell-electrically- | distributed-a... | beamatronic wrote: | The answer to your redundancy question is: Assembly line. | | Instead of ramping up a project, and building 1 of something, | you would plan to do more than one, and you could iterate | over time as you learn. SpaceX is doing a good job of this. | | If 1 Webb telescope is valuable then wouldn't 3 or 5 also be | valuable? | | We have a number of proven space designs at this point: | Soyuz, Spirit/Opportunity rovers. | bernulli wrote: | It's really not - just by having more hardware available | (at higher total expenses) doesn't make the pool of money | available (public research funding) to book time on these | things more. These things are one-off, you build a new one | if you expect 10x improvement over the old one. | | We don't need a fleet of X1 to break the sound barrier for | the first time. We do need many Airbus/Boeings to fly | people and stuff from A to B. | | Note that that is the case with the unique research | hardware you cite as well - we're not sending another | Spirit/Opportunity, but have graduated to something else. | | Soyuz is a different use case, as there is an economic | demand to be filled - that's why a private company like | SpaceX is in that sector with its Dragon. On the other | hand, you don't see SpaceX cranking out Spirits or JWSTs or | Washington Monuments. | twistedpair wrote: | They calculated that. Building a second JWST would have | added 10% to the budget, but the budget committee nixed | that. | | YOLO (you only launch once). | devoutsalsa wrote: | The JWST only has a planned mission duration of 10 years. | If it's as epic as everyone claims it could be, there | must be a follow up mission planned. So even if it fails, | we'll still see a successor at some point. | dylan604 wrote: | >there must be a follow up mission planned | | https://www.universetoday.com/139461/what-comes-after- | james-... | | The write up goes into detail on how missions are | planned, and what is in line to follow JWST. | thebigman433 wrote: | There are quite a few more telescopes planned, I think | the next major one is the Nancy Grace Roman telescope, | which is another infrared scope, made from an old NRO | telescope. The decade survey called for another massive | space telescope to look at the optical and UV spectrums, | so Id expect that to be the next truly big flagship | telescope. | wmf wrote: | Since JWST was delayed ten years the successor will | probably be delayed 20 years and launch in 2050. | yk wrote: | I hope it's just badly thought through marketing. There is | currently a AWS spot during nfl games, that shows a spectacular | catch and then proclaims that the catch probability is only | 3.6% or something. You are meant to be somehow impressed by the | unlikelihood I believe, but that their model thought the catch | is unlikely and the guy caught it implies a rejection of their | model with p=3.6% < 5%. | | The JWST marketing seems to work under a similar premise, they | proudly proclaim that they couldn't mitigate hundreds of single | points of failure, and you're supposed the be impressed by how | difficult their task is. Hopefully the engineering did a | reasonable job and the marketing is just playing up the wrong | thing. | jdiez17 wrote: | I don't think you are supposed to be impressed by the number | of things that could go wrong. At least, that's not how I see | it. They talk about the deployment phase with all these | complex things that have to go exactly right as "the 30 days | of terror." And that's a pretty accurate description of what | many people with a stake in the JWST will be feeling. Not | awe, but terror. This is a big part of space missions at the | bleeding edge of science and technology, and I think it's | great that many people are hearing about it! | jcims wrote: | I think this is your earnest attempt at it but its a good place | to apply the story from yesterday 'be curious, not | judgemental'. | dimtion wrote: | I'd like to apologize if this sounded judgmental. English is | not my main language, and perhaps my phrasing sounded like I | assumed my domain specific opinion is better than the actual | people working on the the project. | | Reading the other comments, and maybe to contextualize to my | question better, I'm more surprised by how the project is | presented as marvelous to the public, rather than thinking | that any technical part were overlooked. | | While I'm sure that engineering teams at NASA and ESA have | countless contingency plans, procedures and failure models. | Medias around the project seem to focus on how fragile the | deployment procedure is. Great engineering is an act of | finding the best balance between opposing constrains, by | building technically sound systems but also more importantly | designing robust human or automated procedures. | | In this story, in my opinion, the media presents a skewed | explanation of why the project is incredible by highlighting | that it would be incredible that such a brittle deployment | procedure would even work. | kataklasm wrote: | That's literally what he is doing, isn't it? He thought | something was off, and instead of spewing his opinion all | over the place he requested information from folks more | versed in the domain than him. He is literally being curious, | not judgemental. | jacquesm wrote: | > I'm always baffled how everyone seems proud that the | telescope has something like 200 SPOF during deployment, | and if even one of them fails the whole mission could fail | | I see this as judgmental, am I wrong in that? | MobiusHorizons wrote: | It expresses an opinion, but I don't think that has to be | judgmental. The OP has to explain their position in order | to ask for additional information. | twistedpair wrote: | While a farm tractor might have a factor of safety of 10, | spacecraft are usually closer to 1.3, due to mass and | efficiency constraints. | | Space is hard. | wslack wrote: | I suggest the book "Failure is not an option" by Gene Kranz, an | Apollo flight director (played by Ed Harris in Apollo 13). He | describes how the primary work of flight controllers in all | missions is risk management. You are constantly balancing | mission needs, fuel needs, mass needs, temperature needs, and | etc etc. | | I don't think that a raw metric of the number of SPOF is the | right way to measure the risk of this spacecraft. It's a fun | term for PR purposes (and emphasizing the risk here) but the | actual risk posture is more complex. | | I imagine that in the course of developing this, they worked | out a possible strategy without all of those SPOF - but doing | so doesn't eliminate the risk, and the impact to mission is | likely massive. | onphonenow wrote: | What I don't understand is for $11 billion - can't we do 3 | $3B space telescopes that work reasonably well? Spread risk? | More science? | | Let's say a Falcon 9 launch is $90M. Falcon heavy let's say | $200M. | | So you take your 3x $3B. Put $200M/instrument into launch, | have $2.8B per telescope leftover. | | There just seems to be something wrong that it costs THIS | much to build a telescope. | | That said, the Thirty Meter Telescope is also a sort of | "forever" job, the delays have stretched on and on. | | I wonder if you did something like bid out and paid just on | performance instead of this forever cost reimbursement thing. | Right now if you can get onto one of these mega projects, and | can stretch it out with delays, it basically can cover your | career (ie, 20 year projects). | foobarian wrote: | I think this is because of how the various constraints work | against each other. We need the telescope to be as large as | possible to work as well as possible. But the rockets can | only be so big (i.e. we're constrained by the largest | available booster). The only thing here under our control | is how hard we work on fitting the biggest possible | instrument in the available payload envelope, and that is | exactly what happened. | | With a machine this complex I think it's also not easy to | crank out multiple copies since I'm imagining most of it is | made by hand without the benefit of a production line. | lamontcg wrote: | JWST is driven by the size of the mirror, the need for an | IR instrument and the temperature you need to keep the | instrument at to do the observations. Spamming a bunch of | hubble-sized instruments up into orbit won't accomplish the | same thing. And I don't think you can do space VLBI in the | optical/IR or it would have been done already (but I don't | know why?). | | It is kind of like asking why 5 Ford Rangers can't replace | one Lamborghini or something. | CamperBob2 wrote: | _Spamming a bunch of hubble-sized instruments up into | orbit won 't accomplish the same thing._ | | It will, and then some, once we get optical | interferometry nailed down. JWST is great, and needed to | be done, and I'm glad it's finally getting deployed. But | if I had an argument to make against it, it would be, | "Let's wait until we know how to do this properly. We're | not there yet." | | That's a weak argument and should almost never be heeded, | but it's also not wrong. | aargh_aargh wrote: | The reason we can't achieve the same resolution as JWST | with interferometry has been mentioned in a recent | startalk podcast. The distance between the telescopes | would have to be coordinated to a precision somewhere on | the order of nanometers. | petschge wrote: | The reason why we are barely getting started into VLBI in | the IR on the ground (and nothing that I have heard of | yet in space) is that the different apertures need to be | stable relative to each other with a precision better | than a small fraction of a wavelength. (One tenth, one | twelves and one twenties are often used, depending | basically on which performance drop relative to the | theoretical optimum you are willing to live with.) | | For radio astronomy, where we do VLBI everyday, we have | to handle waves of wavelength 1 cm and position antennas | to a precision better than a millimeter. Not easy when | the antennas are scattered across the country, but | something we can pull off. | | For IR astronomy we are talking wavelength in the range | of 1000 nanometers to 30 microns. So at the easiest end | of the spectrum you would have to position satellites to | a precision better than 3 microns relative to each other, | while flying on orbit and being pulled and pushed by | tidal forces, gradients in the graviational fields and | solar wind pressure (which contains turbulent | fluctuations). For it to actually work in near IR you | would have to get the positioning right to within 100nm. | | For comparison: The mirrors of JWST itself are flat to | within about 25nm. And in some sense we ARE doing IR VLBI | with JWST since we have separate mirror segments that we | all position correctly relatively to each other. But | doing so we separate freeflying satellites is something | we just aren't capable of yet. | | PS: Yes, LISA Pathfinder has demonstrated measurements of | spacecraft separation down to a few picometer, so we are | slowly getting there. | sjburt wrote: | There are many people in NASA and around that have made | similar arguments. | | I think the real reason that they never have a lot of | traction, sadly, is that if you propose 3, Congress will | give you 2. And then when 2 are over budget, it will get | trimmed to one. Better to propose one big mission and get | it to the point where it can't be cut easily. | dwohnitmok wrote: | Yeah when you have a fickle funding source often the only | way to get any long-term project done is to make it too | big to fail, but then you see all the other terrible | waste, corruption, etc. that accompanies that. | azalemeth wrote: | I'd bet that the vast majority of that cost isn't going to | be materials -- it'll be staff time to design and optimise | the telescope and make something that can work, including | where necessary how to make new materials or processes to | make that telescope. I'm not saying the actual hardware is | cheap by any stretch of the imagination, but making three | different telescopes isn't a linear function of that | budget. They're literally pushing the envelope of what's | possible here. If something terrible happens to the rocket, | lots of forms will be written and people will be sad but | fundamentally I think they'll build something a bit better | on a few years and nail it. A bit like New Horizons | (awesome Mars rover) vs Beagle 2 (awesome Mars rover that | died on arrival to Mars). | rtsil wrote: | JWST was (re)launched in 2005, the very idea of cheap | spaceflight didn't exist back then, so you'd have ended up | with three expensive flights. Also consider that the | expected cost back then was $4.5 billion. | mongol wrote: | Perhaps that is what will happen from now on. But when JWST | was initiated, the options looked different. | Mesisio wrote: | Will this be visually tracked? Like can we watch it to it's | journey? | BurningFrog wrote: | We're told that since JWT will travel very far away before it | unfolds and activates all its systems, there is no practical way | to service it if something would go wrong. | | Why can't it unfold etc in Earth orbit, where a repair mission | can be sent if needed, and _then_ travel to its Lagrange point? | ufmace wrote: | Absent all of the other practical considerations, even in LEO, | a repair mission would probably be so expensive that it would | be cheaper to build and launch a new one instead. | whiteboardr wrote: | Orbiting around earth would require it to constantly course | correct / rotate in order to avoid the device from getting to | hot from the sun's radiation - there isn't enough fuel to "play | it safe" around earth for this long since it will be needed at | L2. | | Let alone the current lack of in orbit service capabilities | like we had when the space shuttle was still around. | Symmetry wrote: | It doesn't have enough fuel onboard to go from LEO to the | Lagrange point itself. | CyanBird wrote: | It wouldn't need to, you could park it there a secondary | liquid fuel booster attached, and then after the origami | shenanigans if it unfolds correctly the second booster could | send it away to its final position | | I saw some interviews of engineers of the jwst and few of | them had similar ideas, or at least to assemble them in leo | then slingshot them to their final positions/orbits | bendhoefs wrote: | What booster would you use? | | Another booster up in the fairing? That would need to be | quite heavy. It would be a totally custom thing for this | specific mission. You would need a suitable storable | propellant. | | Leave the booster from the Ariane attached? The lh2 and lox | would boil off after a few days. | | What do you do if the deployment fails? SpaceX's dragon | can't do space-walks on its own, it doesn't have an | airlock. There would be no way to fix it short of | developing a whole new space craft for that task. | samwillis wrote: | For space walk accessibility maybe they should have | docked it to the ISS for initial setup before then | boosting it to its final point? | zrail wrote: | ISS is in a very low and eccentric orbit. I think | boosting from ISS to a geo transfer orbit, let alone | escape, is more expensive than just going straight to | escape velocity. | devoutsalsa wrote: | We probably wouldn't have a way to service it in earth orbit | either. We needed a space shuttle to operate on Hubble. And | using some other commenter's estimate a 2nd JWST would cost 10% | of the 10 billion USD price of the first one. A billion dollars | is ballpark what it costed to launch a space shuttle. So even | if we had the shuttle, would we fix the first one or just build | & launch a second one? | mabbo wrote: | Can we crowdfund 3 more this way, I wonder? | ultramegachurch wrote: | I suspect the deployed structure cannot handle the acceleration | required for escape velocity. That also may require much more | propellant. Then on top of that, we don't have the capability | for humans to service satellites other than the ISS. So this is | all a moot point. | Mesisio wrote: | Interesting though. | | Does that really matter without air resistance? | | Depending on how high you actually bring it. Like 500km away | from earth is still an orbit (I think that's Hubble's orbit) | but how much force do you need or will happen? | MobiusHorizons wrote: | When rockets are firing lots of acceleration is applied | that the delicate structures are only designed to handle | when stowed. Think long arms on hinges. They can take | acceleration in one axis, but not at 90 degrees to it. | Mesisio wrote: | I guess the acceleration needed to leave orbit might need | so much more fuel if you need to do it slowly than doing | it fast? | | Otherwise it would just take longer. | aliher1911 wrote: | Rocket engines could only be throttled down to certain | power and manoeuvring thrusters would run out of | propellant way before it reaches any orbit. Maybe | something like electric propulsion can do it but it will | take very long time to make it practical imho. | HideousKojima wrote: | The parts of a ship that thrusters are directly attached to | experience acceleration first, the other parts that are | further out from the thrusters won't accelerate immediately | and if the acceleration is too sudden or extreme could be | damaged or break off entirely. | | And to answer your question in the other response, many | thrusters have a minimum thrust, and even that minimum may | be too much for the parts when deployed. | martyvis wrote: | By definition, as long as thrusters are firing, you are | accelerating. | chriswarbo wrote: | Acceleration is defined as the change in velocity, and | velocity is defined as the change in position (w.r.t. | some inertial reference frame). There will _always_ be | some bending when thrust is applied at one part of a | body; nothing is perfectly rigid. | | As an extreme example, imagine a stick one lightyear in | length: if we ignite a rocket on one end, firing | perpendicular to the stick's length, then the other end | cannot start moving for at least a year. | twistedpair wrote: | Rockets can easily accelerate with enough force to kill a | human (cargo flights and unmanned flights use different | launch profiles for this reason). | | The less Gs you need to design a component for, the | lighter/simpler it can be, so why unfurl early and add that | extra mass and complexity to the design? | BurningFrog wrote: | We had the capability in 1993, and could of course develop it | again. | | A broken JWT could wait a few years in orbit. | ultramegachurch wrote: | That may be true, but designing a mission based off that | hypothetical is a bad idea. The reality is we currently | don't have the capability for humans to service satellites, | and developing that capability would probably take years | and cost >$100 million. And NASA can't just decide to take | on that endeavor, it would require congress and months of | political bickering. JWST was designed for what is | currently feasible and practical. | kaashif wrote: | > developing that capability would probably take years | and cost >$100 million. And NASA can't just decide to | take on that endeavor | | So what you're saying is, this could easily be funded by | some billionaire, e.g. Jeff Bezos who already sells | billions of dollars in Amazon stock per year to fund Blue | Origin? | | Not saying this _should_ be done privately, but if | funding is the problem, that problem can be solved. | | Space travel is less expensive than most people think, it | just isn't very high up on our list of priorities. | ultramegachurch wrote: | "Maybe Jeff Bezos could fund this" is not a good | parameter to design a mission around. | BurningFrog wrote: | $100M is 1% of what JWST cost. | | Looks like a reasonable repair cost (and only if) it | turns out to be broken. | ultramegachurch wrote: | It's still not that simple, unfortunately. Ironically, | there are too many single pint failures. Maybe JWST broke | in a way that can't be repaired. Maybe congress doesn't | approve the repair mission. Maybe the repair mission | would actually cost $1 billion. Maybe the repair mission | fails. Now imagine you're the mission designer. You could | trade increased complexity for some small chance of a | repair mission maybe being possible. Or you you could | decrease complexity and just accept that repair won't be | possible. The answer becomes pretty clear. | superjan wrote: | Referring to hubble? The JWT is designed to observe from | the Lagrange point in permanent shadow of the earth. It | won't work from earth orbit. First parking it in orbit, and | then restarting the engine after unfolding comes with a | whole new set of risks and tradeoffs. | alserio wrote: | What about an unmanned mission to fix it? And maybe to refuel | it. | nexuist wrote: | But who repairs the repairers? | ultramegachurch wrote: | Incredibly unlikely. First, it would have to fail in a way | that's possible to fix. We don't have robots that can | replace screws, solder joints, and polish mirrors in space. | Then we'd have to design a brand new spacecraft and | mission. That would take years, lots of money, and | political will. NASA would likely cut its losses, document | the lessons learned, and try again. | mabbo wrote: | It's a problem of energy and orbits. | | To get from low-earth orbit to the sun-earth Lagrange point 2 | (where the JWT is headed) takes around 7 km/s of delta-v[0]. | That's a lot of speed. | | You could try to do this gently enough that the unfurled JWT | won't be damaged by the acceleration. This isn't totally | impossible, but you'd need a good Hall thruster (ion engine) | with a huge amount of reaction mass, since the JWT is so big | itself. It would need to run for longer than any other such | thruster has. It would need massive solar panels to power | it.[1] | | Or you could have the original rocket just be bigger, and throw | it all the way to the right orbit while everything is packed | tight. | | [0] https://en.wikipedia.org/wiki/Delta-v_budget [1] I'm | guessing at this, but that's my intuition. I encourage anyone | to correct me because space is too cool to be upset that I was | wrong. | [deleted] | eterm wrote: | How feasible is a repair mission without the shuttle? | twistedpair wrote: | L2 is very far from earth, well beyond the Moon. The Shuttle | could never leave Low Earth Orbit, so it's a non-factor in | repair missions once JWST is on station. | usrusr wrote: | I believe what was GP was getting at is that even in a | "convenience orbit", a repair mission would be very | unlikely. | buryat wrote: | in Armageddon the Shuttles flew over the moon | dragonwriter wrote: | The shuttle-like craft were explicitly special, more | capable craft (visually hinted at by the extra set of | boosters and other design differences.) | | Not that Armageddon was particularly focussed on reality. | BurningFrog wrote: | The scenario we're talking about is having JWT unfold in | Low Earth Orbit, so it can be repaired there, if need be. | justin66 wrote: | > Why can't it unfold etc in Earth orbit, where a repair | mission can be sent if needed, and then travel to its Lagrange | point? | | Another comment mentioned that it's not designed to accelerate | while it's fully deployed, and that's true enough. You'd wreck | it. | | The other essential thing is that there's no way to give it and | its instruments anything like their designed operating | parameters (pretty hot on one side of the sunshade, something | like 40 kelvin on the other side) in Earth orbit. ___________________________________________________________________ (page generated 2021-12-24 23:00 UTC)