20 ms·
Webb placed on top of Ariane 5
- michielt 5y agoAre there any onboard cams to watch the deployment after it reaches L2?
- lainga 5y agoI can't find an answer to this anywhere: is there a backup JWST (or parts thereof) if this one fails to launch?
- NikolaeVarius 5y agono
- Zealotux 5y agoI'm wondering why is that, which part of the effort was dedicated to research and how much time and money would it cost to build a new JWST?
- guerrilla 5y agoThe reasoning that I heard (and I hope I'm relaying this right) was that if it doesn't work then it will most likely be because of something that needs to be redesigned, so there's no point in producing an exact replica.
- mikepurvis 5y agoI think this assumes a successful launch and some kind of issue with the deployment. The other concern is, of course, what happens if it blows up on the launchpad.
- guerrilla 5y agoPresumably they've actually quantified these probabilities and think that the chance of that is relatively very low compared to the chance of something going wrong in the design. These things are not cheap, so it makes sense not to have to make three if the launch succeeds and design fails.
- mikepurvis 5y agoOh yes, I totally agree— this is a very proven rocket, and the deployment sequence is very, very much not proven. So it absolutely makes sense to have gone this way.
- CamperBob2 5y agoThat's assuming that anything that goes wrong in the deployment sequence necessitates a clean-sheet redesign of the whole thing. No reason to think that.
- mikepurvis 5y agoBut with so many things that could go wrong in such a tightly integrated system, it's impossible to predict which components or assemblies may be affected by a partial redesign.
- CamperBob2 5y agoIf you say so.
- Kaibeezy 5y agoAriane 5 appears to have 96% mean reliability. Source: 2021 Space Launch Report – Launch Vehicle by Success Rate (spacelaunchreport.com) - https://www.spacelaunchreport.com/log2021.html#rate https://www.spacelaunchreport.com/log2021.html#rate https://news.ycombinator.com/item?id=29554274 https://news.ycombinator.com/item?id=29554274
- sho_hn 5y agoI think OP means "what if the rocket fails". The answer is that building another telescope specimen would be quite expensive, even without any changes to the design. The supply chains aren't set up for volume and integration and testing is very involved. I can't put a number on "the second telescope would be x% cheaper", but it would be very disappointing.
- revax 5y agoAlso Ariane 5 is one of the most reliable rocket capable of launching JWST on the correct orbit.
- cbm-vic-20 5y agoIt's also going out pretty far (the L2 Lagrange point on the other side of the moon), so they also won't be able to perform any manned post-launch repair missions like they did with Hubble.
- guerrilla 5y agoActually I have a question about this. What happens if it fails at L2? Is that position like occupied or more difficult to deal with from then on?
- huntsman 5y agoThe L2 point is unstable do energy needs to be expended to maintain position there.
- Out_of_Characte 5y agoSolar wind will push it out of L2 and into an orbit around the sun. This is already going to happen once JWT runs out of fuel to maintain its position.
- messe 5y ago> so they also won't be able to perform any manned post-launch repair missions like they did with Hubble. In terms of hardware that's readily or soon to be available, it is technically possible. Starship, if it gets off the ground, is the obvious choice. Orion could do it, but it would mean dumping another two billion into JWST. If it really came down to it, Falcon Heavy launched with a Crew Dragon sitting on top of it could probably reach it, although it might need an additional kick stage (I haven't done the maths), and it would need to be crew rated first (and SpaceX don't currently have an interest in doing that).
- bumby 5y agoIf you consider the human to be part of that hardware, it's over 4x the distance that a human has ever travelled. There would still be a lot of technical problems to be figured out.
- throwaway64643 5y agoI'd imagine they just cannot fabricate the mirrors as many as they want. The mirrors, arguably the most important parts of any telescope or optical instrument, need delicate manufacture due to the required precision. At the end of the day, this is not automobile industry.
- crate_barre 5y agoMakes me wonder if it would have been smarter to build it in a modular way with different pieces being sent up one at a time, assembled on the ISS, then launched in the direction it needed to go.
- jandrese 5y agoThen you have multiplied your launch risk by the number of launches it would take to get it up there, plus there is the difficulty of assembling it in orbit. The only other project built like that was the ISS, and it took decades and a launch vehicle that no longer flies. The biggest problem would be that it would be in the ISS orbit, which would require a lot of delta-V to get it to its final orbit.
- jbay808 5y agoAn advantage of assembling it in ISS orbit is that you have DEXTRE and a team of spacewalking astronauts available to do the unpacking and assembly!
- echelon 5y agoOr an altogether different design: thousands of cheap, totally fungible sensors in an array at the L2 point. Not only would they be replaceable, but we could increase capacity in the future.
- petschge 5y agoExcept that interferometry at IR is still extremely hard.
- dekhn 5y agohumanity has a lot of experience building reliable one-offs, actually a lot more experience and a lot better experience than with modularity and bits and pieces. I'm a software engineer by trade but every time I look into industry (ship building, skyscrapers, etc) you realize: that aphorism about software engineers, woodpeckers and civilization was absolutely right.
- echelon 5y agoThis is our only shot. They didn't replicate the build. https://www.quora.com/What-would-happen-if-the-James-Webb-Space-Telescope-launch-vehicle-were-to-undergo-a-catastrophic-failure-at-launch https://www.quora.com/What-would-happen-if-the-James-Webb-Sp...
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- mikepurvis 5y agoRelatedly, I'd be curious to know what the split has been of the $10B "program cost" in terms of development vs manufacturing. I assume that like with most things, the vast majority of the cost has been in the design and documentation over its 30 years of development. At the same time, there's obviously a ton of extremely high precision bespoke components in there, so "building another one" would definitely not be trivial.
- 0_____0 5y agoIf it's anything like the hardware engineering programs I've been involved in, at qty=1 the cost is almost all R&D. That includes development of processes to build something like 1.3m wide ultraprecise beryllium mirror segments...
- mikepurvis 5y agoOh absolutely, but I still wouldn’t be surprised if the cost for unit 2 was still another half a billion dollars. It would be fascinating to know.
- bumby 5y agoAerospace isn't necessarily like that for a number of reasons. A large driver of cost is quality control. For example, when a custom part is manufactured it needs to go through a number of tests, some of the raw material needs to be kept and tracked for future testing, etc. When they get shipped they have to be be tracked and handled differently, sometimes accelerometers are placed on the cargo to measure any shocks, etc. They need to be stored in a bonded warehouse, often climate controlled throughout its life. All of that control, testing and documentation adds to the cost even after R&D is a sunk cost.
- BurningFrog 5y agoTo me, this is a major dysfunction of the NASA model. Why wasn't 5 Hubble telescopes launched? The marginal cost for the other 4 must have been vastly smaller than the first. Observation time on the original Hubble is still, after 30+ years a scarce resource. With 5 of them, we could have gotten vastly more science done at smaller cost. I don't have a fully fleshed out theory for why, but part of it is that NASA as a government organization is ultimately a political endeavour, and it will have to optimize for what makes politicians look good in the press, rather than what gives the most science bang per buck.
- spyspy 5y agoEven in high school robotics we built a main chassis and a 1:1 spare for testing and hot swapping parts.
- sho_hn 5y agoThere was. Sort of. https://en.wikipedia.org/wiki/KH-11_KENNEN https://en.wikipedia.org/wiki/KH-11_KENNEN In particular some of the manufacturing tooling for the mirrors were shared, leading to the HST mirror being downsized to 2.4 meters.
- thereddaikon 5y agoIts surprising how many people don't know this all these years later. Hubble is repurposed spy satellite. The main cost of the vehicle isn't in the spacecraft itself though its the optics which are different from those used on KH-11. What is good for looking at Russian military bases doesn't directly translate to looking at galaxies.
- ceejayoz 5y agoIn fact, the NRO donated two Hubble-like KH-11s in 2012, on the condition that they not be used to observe Earth. https://en.wikipedia.org/wiki/2012_National_Reconnaissance_Office_space_telescope_donation_to_NASA https://en.wikipedia.org/wiki/2012_National_Reconnaissance_O... One of them forms the base of https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telescope https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telesc....
- kilroy123 5y agoNo, and I think they should have made two of them.
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- findalex 5y agoImagine having the replacement gold reflector dish in storage somewhere.
- dotnet00 5y agoIt's worth considering that nowadays we don't really do backup copies of satellites/probes because launch is pretty reliable by now, especially on rockets that have been flying for a while (which is pretty much a requirement to be chosen to launch a flagship project like JWST). Ariane 5 has a long flight record with very few failures and the design has been further carefully reviewed specifically for JWST, with the previous two launches having served as verification for any fixes that needed to be made prior to flying this mission. Basically, the chance of JWST being lost due to a rocket issue is much lower compared to the chance of it being lost due to design issues with the telescope itself.
- dgrin91 5y agoThe answer is no for mainly two reasons: 1. Prohibitive costs. Its extremely expensive (both in money and time) to manufacture many of the parts of the telescopes, such as the reflector dishes. Its even more expensive to do all the testing & certification of the manufactured parts. 2. Its all outdated anyways. The JWST project has been ongoing for literally decades (starting in '96 if I remember). If we were to start from scratch today we would make a lot of different design choices based on more recent technological developments
- gibbonsrcool 5y agoI would love to see a video where one of the engineers on the project talked about what would be different if Webb was started today. Materials, software, processes, everything!
- p_l 5y agoA huge design issue that might - or might not - be pushed would be the power system. Solar panels require that JWST stays in the sun while conducting observations, while at the same time being critically dependant on the observing equipment to be cool - and being unable to just keep it inside bigger structure like with Hubble. This means that there's a huge problematic sun shade structure which is considerable part of the SPOFs still endangering JWST even if it is inserted into orbit correctly.
- ufmace 5y agoNope. Wouldn't be a good use of money anyways. If it fails, it might be because of a design or manufacturing flaw. Better to make the new one after we have some idea what went wrong.
- remram 5y agoWhen's the launch date? I couldn't find a definitive answer, as both December 18 and December 22 are listed.
- _Microft 5y agoDecember 22, delays are always possible but it's not going to launch earlier than that ("no earlier than" is often abbreviated "NET" in that context). https://jwst.nasa.gov/content/webbLaunch/countdown.html https://jwst.nasa.gov/content/webbLaunch/countdown.html
- stanmancan 5y agoDecember 22nd; they were aiming for the 18th but there was a small issue that required a bit of additional testing so they pushed it back to the 22nd.
- gizmo385 5y agoWasn't the most recent 18 -> 22 delay because they dropped it?
- gdecaso 5y agoYep.
- progbits 5y agoThey didn't drop it but a clamp released unexpectedly during some operation and it caused vibrations in the telescope. At that time they didn't have sensors attached that would be able to confirm if the vibration was within specified tolerances so manual inspection of sensitive components had to be done again. Glad to hear it went well and we are back on track!
- petschge 5y agoWell. It has shifted to the 24th now: https://blogs.nasa.gov/webb/2021/12/14/webb-space-telescope-launch-date-update/ https://blogs.nasa.gov/webb/2021/12/14/webb-space-telescope-...
- qwertyuiop_ 5y agoI hope it works up there. They dropped it https://blogs.nasa.gov/webb/2021/11/22/nasa-provides-update-on-webb-telescope-launch/ https://blogs.nasa.gov/webb/2021/11/22/nasa-provides-update-...
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- findalex 5y ago> caused a vibration throughout the observatory. I hope there won't be vibrations during the launch of the rocket.
- mort1merp0 5y agoThe launch vibrations and their resonance frequency are accounted for in the design. The unplanned vibrations due to this mishap was not planned for. I understand they ran some tests and calculations after the accident and believe that the instruments are good to go.
- zamadatix 5y agoOne means you felt something else have an bad day, the other means you had a bad day.
- redis_mlc 5y agoFrom your link, it doesn't sound like they dropped it. A clamp band "released" causing vibration, but that is not the as a 1g fall to the hard floor. This is one of the few NASA projects to actually care about, since the Shuttle and the ISS were flaming moneypits. Virtually no science has ever been done on the ISS, even compressing it's entire history into a single year - it's that worthless. (Another HN reader confirmed that by reading NASA's junk PR releases about ISS.)
- ceejayoz 5y agoCould've been worse. https://en.wikipedia.org/wiki/NOAA-19#Damage_during_manufacture https://en.wikipedia.org/wiki/NOAA-19#Damage_during_manufact...
- ashton314 5y agoThe launch is super scary, but the deployment seems even worse. When will we know whether or not all is working? I don't know if I could handle that much pressure to launch that thing.
- danielodievich 5y agoI am there with you. I've been watching this unfold for half of my life, and seems like EVERYTHING must go right for it to happen. The unfold is scary complex. I really, really, really, really want it to go right and worry. On other hand, NASA has done this amazing thing with landing rovers on Mars flawlessly and those were incredibly complex processes with sophisticated pieces of engineering. biting my nails here
- edoceo 5y agoHow about Cassini? (sp?) threw this little sensor disk to Saturn for information - what a cool project.
- Rebelgecko 5y agoAll the scary stuff that can go catastrophically long is within the next 40 days or so. However it'll take months to go through the calibration process, tweak the mirror positions, check out optics, etc
- jessriedel 5y agoYea, I'm having trouble finding a detailed schedule, but it looks like the main mechanical components are all deployed in the first 15 days https://upload.wikimedia.org/wikipedia/commons/6/6a/JWSTDeployment.jpg https://upload.wikimedia.org/wikipedia/commons/6/6a/JWSTDepl... https://webbtelescope.org/contents/media/images/4180-Image https://webbtelescope.org/contents/media/images/4180-Image After that they still need to a do a ton of checks, wait for outgassing, etc. The first "science-quality images" are expected by the end of the third month.
- uplifter 5y ago
- _joel 5y agoI've never been so nervous for a launch in my life.
- Mountain_Skies 5y agoI'm more nervous about the deployment. There are so many things that can go wrong after the launch but before it is fully operational.
- baggy_trough 5y agoI never thought the Mars rover sky crane would work, but it did!
- _joel 5y agoI think most of the engineers on the project didn't either, what did Adam Steltzner, something like "It was the least worst option out of a lot of bad options". I'm sure there's a commentary there on modern life, but sod that, this far cooler than any addage :)
- marvin 5y agoI saw an HN comment once, purporting to come from a NASA engineer that quit over disillusionment from being certain that the sky crane maneuver would never work.
- fortysixdegrees 5y agoAlthough I guess once it's in orbit, and major problems could be sorted out over the following years with manned repair missions, like they did with hubble
- FourHand451 5y agoNot really, unfortunately. Webb will be much further from Earth than Hubble is, so as far as I'm aware a human mission to go repair it isn't really considered an option. https://www.nasa.gov/topics/universe/features/webb-l2.html https://www.nasa.gov/topics/universe/features/webb-l2.html
- pelagicAustral 5y agoTalking about Ariane 5, it's been interesting reading parts of its history. Particularly: "Ariane 5's first test flight (Ariane 5 Flight 501) on 4 June 1996 failed, with the rocket self-destructing 37 seconds after launch because of a malfunction in the control software. A data conversion from 64-bit floating point value to 16-bit signed integer value to be stored in a variable representing horizontal bias caused a processor trap (operand error)because the floating point value was too large to be represented by a 16-bit signed integer. The software was originally written for the Ariane 4 where efficiency considerations (the computer running the software had an 80% maximum workload requirement) led to four variables being protected with a handler while three others, including the horizontal bias variable, were left unprotected because it was thought that they were "physically limited or that there was a large margin of safety". The software, written in Ada, was included in the Ariane 5 through the reuse of an entire Ariane 4 subsystem despite the fact that the particular software containing the bug, which was just a part of the subsystem, was not required by the Ariane 5 because it has a different preparation sequence than the Ariane 4" I wouldn't want any part on something as mission critical as getting a rocket to deliver something into orbit.
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- pkaye 5y agoLooks like 95.5% success rate. I don't know if there is anything better with that much payload capacity and as long a track record. https://en.wikipedia.org/wiki/Ariane_5 https://en.wikipedia.org/wiki/Ariane_5
- ceejayoz 5y agohttps://en.wikipedia.org/wiki/Delta_IV https://en.wikipedia.org/wiki/Delta_IV and https://en.wikipedia.org/wiki/Atlas_V https://en.wikipedia.org/wiki/Atlas_V have essentially perfect records. The IV had a lower-than-expected orbit on a non-payload test flight, and the V had a lower-than-expected orbit that the payload was able to fix.
- YossarianFrPrez 5y agoI keep reading about how there are ~350 single points of failure once Webb is successfully launched. Can someone with expertise and chime in about why the telescope wasn't designed with more built-in deployment redundancies? It would seem to be good engineering practice to ensure that there are back-up systems, etc.
- evgen 5y agoRedundancy costs mass and there are a lot of deployment steps that simply cannot be made redundant. The trick is folding everything to fit into the constraints of the payload fairing. Good engineering is to design within these limits and but if you make it too safe you end up with something that is not worth launching.
- hollander 5y agoPlus you don't get to send a Space Shuttle to L2 in case the mirrors are malfunctioning.
- bumby 5y agoRedundancy is only one way to increase reliability. For example, having redundant elements can allow you to use cheaper components and meet the same level of reliability as a single, more expensive component but at the cost of mass (or vice versa). Most often, there are reliability requirements that are defined at a very high level, and a reliability engineer helps determine the right tradeoffs to meet those requirements. In addition, some of the points of failure don't lend themselves well to redundancy, like release mechanisms. For certain risks, like human-rated spaceflight, they may just have requirements like "no single-point failures", which means redundancy is a must.
- natch 5y agoOn the ESA web page… 4 likes. Come on, world! We can do better than that.
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- pgen 5y agoDeployment sequence: https://www.youtube.com/watch?v=RzGLKQ7_KZQ https://www.youtube.com/watch?v=RzGLKQ7_KZQ
- NikolaNovak 5y agoI could be wrong, but I feel SpaceX has mastered how to add pizazz to such videos :-)
- nabla9 5y agoSuper exiting. - JWST costs ̃$8.8B USD, about the same as aircraft carrier, or Large Hadron Collider and it goes into a rocket! - JWST has 344 single-point-of-failures, 80% of them related to deployment. Mars landers have significantly less If I remember correctly. If each single-point failure has 0.0001 failure probability, the mission fails with 3.4% probability. If each single-point failure has 0.0002 failure probability, the mission fails with 6.6% probability.
- davesque 5y agoI've found that there's a weird internal psychology I have with any news relating to Webb. I'm just as excited and hopeful as everyone else. But somehow the whole story underscores the perils of singular hope. It also seems to underscore the inherent issues with massive, carefully planned, "vertically" scaled science projects a la 20th century NASA. I've carved out a little nook in my psyche to cope with the outcome that something goes wrong during the Webb's incredibly complicated launch process and all those years of effort come to nothing. It's also made me wonder if there's a way for humanity to pivot to more "horizontally" scaled science. I'm imagining a kind of science conducted by aggregating the data collected by many cheap, easily produced instruments instead of a few incredibly fragile, extremely difficult to build contraptions. I have an intuition that we'll increasingly run up against practical limitations in undertaking ever more complex projects of this kind in the coming years.
- holoduke 5y agoWe do actually. One area in which we make enormous progress is simulation. The entire perseverance trip was almost perfectly simulated in a simulator. It's predecessor only partly. The JW launch and deploy steps are also simulated in a very detailed way. Many different (fault) scenarios are tested. I have good faith everything will go as planned.
- indolering 5y agoThat's sounds really interesting! Any resources for the layman that would provide more detail?
- bumby 5y agoI think these are large vertical projects because of the nature of the problem. I.e., the data we're after is inherently obfuscated by our earthly dwelling so we need to get our instruments a long ways "out-there". And to do so incurs a lot of risk and, generally speaking, the only institutions large enough to incur a risk that large without much profit upside are governments. Now maybe we'll find clever ways to get different data cheaply that meets similar ends, but that seems to be hinged on hope at the moment.
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- pugworthy 5y agoThis fills me with anxiety. It's like "PLEASE DO NOT BLOW UP!!"
- Nick87633 5y agoDec 22, several minutes of terror followed by ~33 days of nail biting until the majority of deployment is complete
- M2Ys4U 5y agoUnfortunately the launch is now no earlier than 24 December
- sinuhe69 5y agoI think the problem with such projects is not only they’re incredibly complex, but also they are NOT modular and not organized as a bootstrap. If any part of the launching or deploying process goes wrong, the whole endeavor could ultimately fail. On the other hand, if we somehow could make the telescope from many equal parts, transport them into orbit, assemble and test it part by part, organized in stages with each stages the telescope will become more powerful then I believe the chance of success will be much higher. Of course with our current technology and industry base, assembly in orbit might cost significantly more. But in the long run, I don’t think we’ll have any better alternative. The most import aspect is however, if due to any error a transport ship exploded or a robotic arm jammed, the entire project will not in jeopardy.
- onion2k 5y agoAssembly in orbit would probably be impossible. The telescope has tolerances measures in microns. You just can't do that as a modular system.
- Ekaros 5y agoI would actually even want to see something like that done on Earth even with remote control. That is bring multiple pieces with trucks to single location and then combine them together without non-remote human involvement. And have the whole thing work as expected inside specs.
- trollied 5y agoLaunch delayed: https://blogs.nasa.gov/webb/2021/12/14/webb-space-telescope-launch-date-update/ https://blogs.nasa.gov/webb/2021/12/14/webb-space-telescope-...