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The James Webb Space Telescope – making 300 points of failure reliable
- anotheryou 5y agomeh, the whole article is just a teaser for upcoming articles and not much more than a single line about what they did with webb "The only solution left [...] was making sure that the JWST would be as reliable as possible. [...] I plan for the next few articles to be split between further details of the James Webb Space Telescope"
- flyyingbarron 5y agoWell yes, this is an introductory article to a series of articles.
- anotheryou 5y agoYes, totally fine as that. I just expected more after the title and I'm a bit annoyed by pre-news and announcements on HN in general. I'm really looking forward to some details and followed you on twitter (because I have no Idea how I would do that on medium without ail spam... I miss RSS...) The only source for details I found so far was an old videolog that at least showed some close-ups of things in action too. https://www.youtube.com/watch?v=7DQe-OzrcJM&list=PLcy1hEnsejK3b0LARG4O4xeCqLDuSNrFZ&index=38 https://www.youtube.com/watch?v=7DQe-OzrcJM&list=PLcy1hEnsej...
- Vinnl 5y agohttps://flyingbarron.medium.com/feed https://flyingbarron.medium.com/feed
- anotheryou 5y agoyea, but I'm not using my RSS reader anymore because it's not as common anymore :/
- lovecg 5y agoI just recently got into RSS and was pleasantly surprised to see that virtually all websites I regularly read provide it.
- anotheryou 5y agomaybe I should give it another go :)
- readthenotes1 5y agoAll fluff, no stuff
- fnord77 5y ago> But the JWST was not designed or tested in a vacuum this is false. NASA has a house-size vacuum chamber that was used for testing. Also the author got the price tag wrong. I wonder what else about the article is incorrect.
- flyyingbarron 5y agoYes, the price error was a typo which has been fixed. "not designed in a vacuum" was a figure of speech, meaning that testing it was done in the context of previous missions.
- CartyBoston 5y agopeeps here can be very literal, it's I suspect no accident
- smoe 5y agoIn the NASA live stream yesterday, during one of the interview a engineer mentioned, that one of the harder aspects about the primary mirrors (if I remember correctly), was figuring out how to test the equipment in the cryogenic vacuum chamber. What they mentioned they couldn't fully test, was deployment in zero gravity. So far I think NASA has done a great job, trough blog posts, videos, websites explaining and visualizing different aspect of JWST in a way that is tangible for laypeople.
- guenthert 5y ago> What they mentioned they couldn't fully test, was deployment in zero gravity. Just test it once right side up and once upside-down ;-)
- kortex 5y agoIt's a figure of speech. Looks like TFA clarified: > But the JWST was not designed or tested in a vacuum (pun only partially intended) It's not the clearest writing, even though they are going for a joke. JWST was not "designed or tested in a vacuum" [in isolation without knowledge of prior art]". But it was designed for vacuum and its parts were tested in a vacuum, including I believe bringing the whole assembly down to cold vacuum. Designing in a literal vacuum sounds painful for the designers. :)
- markonen 5y ago1) The JWST is not in the shadow of the Earth. It’s solar powered. 2) It didn’t cost 9,000,000 dollars to build. That’s off by 1000x.
- ironSkillet 5y agoMy guess is that the content you are referencing in your 2nd point is really the author's failed attempt at a variant of the "it's over 9000" meme. Nobody could reasonably think that it costs in the ballpark of $9 million.
- flyyingbarron 5y agoNo, it's simply a typo, missing the final ",000". It's been fixed now, thanks.
- ironSkillet 5y agoThanks for fixing it. The internet has taught me to be wary of meme references everywhere.
- munchler 5y agoTo elaborate on point 1: Although L2 itself is in Earth’s penumbra, the orbit of JWST around L2 is not in the earth’s shadow at all. (In fact, JWST will orbit L2 at a distance greater than the distance from the earth to the moon.)
- flyyingbarron 5y agoThanks. Changed that to "while staying behind the Earth"
- mehphp 5y agoI only skimmed the article and found a few errors...
- flyyingbarron 5y agoSorry about that! The price was obviously a typo :( What other errors did you find?
- jffry 5y agoJWST doesn't actually stay right in L2 (which is in Earth's shadow). Instead it orbits around L2 about twice a year in a halo orbit, with a radius large enough that it can have nearly constant access to solar power (I do not know if it fully avoids the moon's shadow). You can see a good animation near the top of https://www.jwst.nasa.gov/content/about/orbit.html https://www.jwst.nasa.gov/content/about/orbit.html
- flyyingbarron 5y agoThanks. Changed that to "while staying behind the Earth"
- spiderice 5y agoAwesome link. Thanks for posting. I'm wondering, does anyone know why we didn't send JWST to L4 or L5, where (as mentioned in the link above) it could remain orbiting indefinitely without the need for fuel? Is it because those points are a lot harder to get a spacecraft to?
- jffry 5y agoJWST is making observations in orange to mid-infrared wavelengths. The sun, earth, and moon are all quite hot and emit a lot of light in that range of wavelengths. Near L2, JWST can use one sunshield to block out light from all three bodies, with less impact on what portion of the sky it can observe
- alt219 5y ago
- 7373737373 5y agoIf I see the "300 points of failure" mention one more time without them providing a list of these said 300 points of failure, I'm going to go insane
- kayodelycaon 5y agoYou might like this instead: https://youtu.be/uUAvXYW5bmI https://youtu.be/uUAvXYW5bmI
- _Microft 5y agoDo not get too excited for such a list though because I think around 180 of them were just bolts, locks or actuators securing the movable parts of the primary mirror.
- guenthert 5y agoJust? It's my understanding that each of those could have failed to deploy and if any of those would have, it were the end of the JWST. No way to repair or salvage. No 30% mission targets achieved or "underperforming" (as e.g. Hubble before the mirror correction, i.e. with approximated correction done in software on the ground). Nothing of value, just a flying, very expensive, brick.
- dev_tty01 5y agoYou might find this interesting: https://space.stackexchange.com/questions/44093/details-on-the-single-points-of-failure-in-the-jwst https://space.stackexchange.com/questions/44093/details-on-t... The discussion includes links to several relevant GAO reports. I agree that it would be interesting to see a single detailed list. That is not in these reports. https://www.gao.gov/assets/gao-20-224.pdf https://www.gao.gov/assets/gao-20-224.pdf https://www.gao.gov/assets/gao-16-112.pdf https://www.gao.gov/assets/gao-16-112.pdf https://www.gao.gov/assets/gao-16-112.pdf https://www.gao.gov/assets/gao-16-112.pdf
- dmead 5y agoSometimes, the art world has articles about paintings... Without a picture of the painting.
- nixass 5y agoMore like "300 points of success" :)
- guenthert 5y agoI find it difficult to comprehend how much a risk they were taking. Documentation of some tests is publicly available; it's even mentioned that they found problems and had to partially redesign (and supposedly re-test). If a bolt (or rather one quite like it) has been tested successfully 100 times in the expected conditions, chances are it'll work when needed, but I get a sense not all of those parts in the 300 single points could be tested that often (material cost, time, availability of sufficiently large climate chamber capable of simulating outer space condition). Were there actually parts too expensive to test even once? Is JWST sailing on prayers?
- HPsquared 5y agoIt's complicated for sure, but I still don't understand why it cost $9 BILLION. That's a lot of zeroes!
- jacquesm 5y agoBecause there is only one (no economies of scale), because it is large, because it is insanely precise, because it has to work the first time, because it is traveling very far, because it has to withstand the stress of launch, be 'foldable' (far easier said than done), because they encountered a number of problems while testing the various subsystems requiring re-design/re-manufacture, because it runs a delta-t of 290 some degrees celsius across a two meter distance and so on. This is probably mankind's most amazing technological achievements bar none.
- DerSaidin 5y agoWhen you put it like this, 9 billion sounds like a good deal :) Also, consider how many (presumably) well paid expert engineers are scientists have been working on this since 1996.
- ngcc_hk 5y agoThat is their most productive life for many. And if that fail nothing fail … some compensation is a must. I hate these “well paid” words. I respect the risk and just hope the people working on it has proper life.
- ddalex 5y agoMy understanding is that most off the money went into designing and extensively testing one off components that work reliable in extreme environments. Engineers are expensive
- madengr 5y ago
- 5y ago
- 323 5y agoGiven the many years of launch delay, did they use the opportunity to upgrade some components, like CPU or camera sensor?
- terramex 5y agoNo, cameras' resolution is limited by diffraction that is a function of mirror size. JWST achieves that diffraction limit in range between 2 to 28.5 micron where most of it observations will be performed. As for sensitivity, installed instruments are state of the art, finding any improvements would necessitate multi-year research programs. CPU it uses is RAD750, pretty standard radiation-hardened CPU for spacecrafts. https://en.wikipedia.org/wiki/RAD750 https://en.wikipedia.org/wiki/RAD750 More powerful and modern CPU would not enable any more science to be gathered and only increase chance of failure. Maybe some power saving could be achieved, but that CPU requires only 5W from 2000W produced by solar panel anyway.
- 323 5y ago> As for sensitivity, installed instruments are state of the art, finding any improvements would necessitate multi-year research programs. That was exactly my question. Did they use the 8 years from 2013 to 2021 to improve the instruments? Or did they remain at 2013 state of the art level?
- jacquesm 5y agoThat would require an increase in the size of the mirror, which would mean a complete redesign of the satellite. It is already at the limit of what can be observed with a mirror that size so a better sensor won't automatically give you better images.
- 323 5y agoIf you look at professional cameras (Sony Alpha for example), the sensors improved in the last 10 years from taking shitty pictures at night to being able to take pictures in almost total darkness. All this with little improvements in optics. So is the telescope sensor able to count each and every photon hitting it, was it already at maximum possible performance?
- TheHideout 5y agoIt's unfortunate that the article speaks so much of NASA engineers and managers, but fails to mention the actual engineers that designed, built, and tested it: TRW (now Northrup Grumman) and Ball Aerospace. > The concepts used to create the JWST are built on the same concepts used on the first satellites and space probes in the 1950s. AKA, the field of Systems Engineering [0]. Further reading if you really want to take a deep dive [1]. [0] https://en.wikipedia.org/wiki/Systems_engineering https://en.wikipedia.org/wiki/Systems_engineering [1] https://www.amazon.com/Mission-Analysis-Design-Technology-Library/dp/1881883108 https://www.amazon.com/Mission-Analysis-Design-Technology-Li...
- flyyingbarron 5y agoFair enough, but I felt that detailing the contractors would lengthen the article and not add to my general points. I did mention Northrup Grumman engineers in the caption of one image.
- behnamoh 5y agoHonestly, you writing it on medium is itself a failure point. Many people can't read it due to medium's shady paywall business.
- cardosof 5y ago+1 for systems engineering. Sadly it isn't more common in software development.
- da_chicken 5y agoIt was when software delivery involved distribution of physical media. Now that it's all done over digital networks, people have moved to early deployment models where failure in the customer's hands is all but ubiquitous.
- jacquesm 5y agoIndeed. I see this as our downfall: if the price of failure drops then failure becomes commonplace.
- everyone 5y ago" the JWST will orbit the Sun while in the shadow of the Earth. This will allow it to keep the temperature of its delicate instruments at just the right... " Well that's just totally wrong.
- flyyingbarron 5y agoThanks. Changed that to "while staying behind the Earth"
- redtexture 5y agoBeyond. Or farther away from the sun than the Earth and Moon. Behind implies in the shadows of Earth.
- wolverine876 5y agoDoes anyone know who the author is (beyond the name) and what their background is? Do they work at NASA, for example?
- nerevarthelame 5y agohttps://www.linkedin.com/in/flyingbarron/ https://www.linkedin.com/in/flyingbarron/ "I'm a solution engineer specializing in AIOps, SRE, & ChatOps. I enjoy helping others solve problems even more than I enjoy solving them myself. Besides my IBM work, I also write about SRE lessons from the early era of space exploration - the race to the Moon and the Space Shutte - at https://flyingbarron.medium.com https://flyingbarron.medium.com I'm a published author and I speak for myself and IBM at global conferences."
- octocop 5y agoWhy parts of the instruments need to be cooled below 50K? Do they have quantum computers on the JWST?
- echelon 5y agoSince JWST is trying to pick up weak infrared signal from the furthest reaches of the cosmos, any amount of noise would distort our measurements. The telescope itself will naturally radiate infrared heat (much like our own bodies do), which is exactly what the instrument is trying to measure. This is why they're cooling the instrumentation side to such a cold temperature that it won't emit infrared energy and ruin the science.
- octocop 5y agoAllright, so is that why it takes ~6 months of waiting time now? Would it not be possible to just measure the heat radiated from JWST and subtract it from readings?
- vlovich123 5y agoSensors that can measure the heat will themselves be putting out their own heat. The scientists who built this thing are pros.
- jakeinspace 5y agoMeasure thermal noise? The amount of information contained in the black body radiation of a warm (well, really cold, but not cold enough) object must be absolutely immense, at least when you care about a signal at the level of single photons. Trying to capture it with sensors is futile. Sure you can try to do some noise suppression with a simplified model/probability distribution, but that won't work well if your signal to noise ratio is 0.00001.
- koziserek 5y agoThat would be like throwing a beam of a light from a powerful flashlight 10 cm away from his face when he watches night scenes from last season of Game of Thrones, and saying ”just ignore these 1000 lumens, tell me what is happening?”
- WalterBright 5y agoThe article talked about redundancy in the form of making duplicates. Another way (the way airliners are built) is onboard redundancy. Modern airliners have zero single points of failure.
- oldgradstudent 5y ago> Modern airliners have zero single points of failure. The have zero points of failures that are classified as single-point-of-failure. Once in a while, the classification turns out to be incorrect, as seen in the 737 MAX crashes, especially the first one.
- WalterBright 5y agoThe redundancy in the MAX crashes was the pilots following the runaway trim procedure. Of the 3 MAX incidents, the one you never hear about is the one where the pilots followed that procedure and continued the flight normally. Boeing still should never have had the MAX system rely on only one AOA sensor.
- sumedh 5y ago> pilots followed that procedure Were these pilots trained with the new procedure and the other pilots who died not trained?
- WalterBright 5y agoNo. It was the LA flight immediately prior to the LA flight that crashed. They trimmed it back to normal a couple times, then just turned it off. Sounds too simple to be true, but it is true. There's a toggle switch on the console that cuts off power to the trim system. It's there in case of runaway trim.
- mlyle 5y agoJust to add, it was the normal "runaway trim" procedure-- nothing new. The thing is, this revealed a vulnerability: real pilots in runaway trim scenarios do not do nearly as well as they do in training. And 737MAX ended up testing crews with runaway trim scenarios at a much higher rate than they had been at the past. Some crews failed.
- ncmncm 5y agoHow far back in time do they need to look for x-rays emitted to arrive in the red-to-infrared range the telescope is equipped for? E.g., will we have to rely on x-ray emission from the earliest stars to be able to see them here/now in far infrared?