[HN Gopher] The James Webb Space Telescope has passed the final ...
___________________________________________________________________
The James Webb Space Telescope has passed the final mission
analysis review
Author : guerrilla
Score : 395 points
Date : 2021-07-07 17:26 UTC (1 days ago)
(HTM) web link (www.asc-csa.gc.ca)
(TXT) w3m dump (www.asc-csa.gc.ca)
| thangalin wrote:
| Time-lapse video of it opening (~1:20):
|
| https://www.bbc.com/news/science-environment-57078657
| sghiassy wrote:
| OMFG!!!! I'm so excited... let's go!!!!!!!
| cromwellian wrote:
| I feel like this is an all-eggs-in-one-basket mission. If it
| fails to launch, we have nothing.
|
| Why not build many JWSTs, surely the cost per unit would go down,
| and launch more than one?
| chorsestudios wrote:
| The cost per unit would probably remain around the same. You
| don't really get price cuts for ordering 2 of a custom
| component instead of 1
| wolverine876 wrote:
| > surely the cost per unit would go down, and launch more than
| one?
|
| Surely? They didn't build a JWST factory. It might go up, as
| people with specialized skills or knowledge have moved on.
| dgrant wrote:
| I think the verb tenses were not perfect... I think he just
| meant: why did they build only 1 in the first place? They
| could have built N instead, at a lower cost per unit.
| dylan604 wrote:
| Space/Science/Military spending do not seem to follow the
| normal rules of civilian production nor schedules. Alos,
| once the satellite is built and launched, there is the
| ongoing budgeting of the actual operations of the
| satellite. The budgets are limited in those capacities as
| well.
| jasonwatkinspdx wrote:
| Because there's only one L2 point, and it'd be very risky
| to have two units orbiting. So your spare would just sit
| around costing money in the case the first one works. The
| folks that do this are pretty dang good at what they do, so
| they're willing to bet $10 billion on success the first
| time, vs $20 billion to hedge with a spare. Even with a
| spare it's not clear to me a malfunctioning first example
| would have enough Delta-V to get it safely out of the L2
| point proximate.
|
| If it fails, they'll learn all they can, then try again
| with another follow on project, that likely will take
| advantage of technological improvements since functional
| requirements on this one were set in stone. Pre-building a
| spare just doesn't make sense with this kind of project.
| cromwellian wrote:
| Yes, surely. Most of the cost was in R&D and in the mirror
| manufacturing. They've been designing and manufacturing it
| for 20 years. Per-unit costs would go down. Take the mirror,
| it's made of segments, the facility used to produce those
| segments certainly would benefit from scaling up production.
| They'd get better at fabbing them over time, increasing
| yields, reducing costs.
|
| What NASA is doing is building the equivalent of a $10
| billion fab to produce one chip. Space telescopes could be
| continually produced on a schedule, and retired on a
| schedule, with constant improvement.
|
| Look at RS-25 engines vs Raptor engines in terms of costs to
| produce one.
| wolverine876 wrote:
| Increasing production from 1 unit to 2 doesn't necessarily
| reduce costs. Due to demand and limited supply, for
| example, some prices increase. We know almost nothing about
| this thing. It's very speculative to say the cost would
| decrease. Also, how many space telescopes of this variety
| do we need?
|
| All that said, it would be interesting to see NASA research
| on mass producing the more common components of its
| 'product line'. It does it for rockets, of course, but
| computers? Solar panels? Mars rover components? I'm sure
| it's been considered and I expect it's done in ways I'm not
| aware of.
| bumby wrote:
| Certainly a lot of the cost of the project is R&D, but most
| people would be shocked by how much of aerospace project
| budgets are driven by quality. E.g., a bolt costs $200 not
| because it has to go through a new R&D cycle, but because
| it needs a chain-of-custody, inspections, metal coupons
| stored, etc.
|
| There's also a huge amount of political risk for a
| government entity. Politicians will be reluctant to fund
| another JWST if the first one fails because many will fight
| it as a waste of money, and the previous failure just
| bolsters the JWST-opponent's position.
| cnlevy wrote:
| Looks like it just gave Elon Musk some ideas
|
| https://www.reddit.com/r/spacex/comments/ofqm8o/elon_musk_us...
| tectonic wrote:
| Such an exciting, and high stakes, and dramatically late and
| over-budget mission.
| me_me_me wrote:
| Still better than a failed jet fighter. At least we will have
| working telescope. Even if all we get out of it are some photos
| for a wallpaper for PC. Still better value as something is
| better then nothing in this case.
| Goety wrote:
| I am so amped for this telescope. I hope it exceeds my
| expectations.
|
| It also looks like this location will be quite crowded in the
| future
| https://en.wikipedia.org/wiki/List_of_objects_at_Lagrange_po...
| sitkack wrote:
| We really should have a big science lab up at L2
| Goety wrote:
| Agreed. What else would you put up there?
| tomschlick wrote:
| Government red tape and contracting at its finest
|
| Edit: Downvotes with no comments as to why... This thing is 24
| years in development and 20x over budget. If thats not a
| failure of government contracting, budgeting, etc then idk what
| is:
| https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Cos...
| - Obviously the platform will be cool once they get it
| launched, but until then its just a money pit.
| DubiousPusher wrote:
| It's because this is a flippant, unhelpful attitude. If we
| were talking about building a mile of blacktop highway then
| such a casual observation about the overrun might be
| warranted.
|
| But we're not talking about that. We're talking about
| building the first non-orbital space telescope in human
| history. To a certain extent, no one could know the actual
| cost ahead of time. It's one of those things you kind of have
| to do and it will cost what it will cost.
|
| Was there waste I this project? Probably. But there's a good
| chance the overruns are dominated by true "found work" rather
| than waste.
|
| In fact, this is exactly the kind of project you want handled
| by the government because the cost of failure is so high. In
| a project where you need to push the risk out as many decimal
| places as possible it is good to have an agency which can
| afford the overruns to do it.
| perihelions wrote:
| _" the first non-orbital space telescope"_
|
| There've been a few others, including Gaia (SEL-2 halo
| orbit -- same as JWST), and Kepler (heliocentric). [edit]:
| also Herschel (SEL-2)
|
| https://en.wikipedia.org/wiki/Gaia_(spacecraft)#Launch_and_
| o...
|
| https://en.wikipedia.org/wiki/Kepler_space_telescope#Orbit_
| a...
|
| https://en.wikipedia.org/wiki/Herschel_Space_Observatory#La
| u...
| DubiousPusher wrote:
| Interesting. I assumed these were in orbit like other
| satellites. I didn't realize they operated from the
| Lagrange points. Thanks.
| omgwtfbyobbq wrote:
| I think you're getting downvoted because what you're saying
| doesn't match up with the wiki article you linked.
|
| The original estimate was for $1.6 billion, in I'm guessing
| the 90s, and the estimate had been updated to $5 billion by
| the time it was formally confirmed for construction.
|
| > The telescope was originally estimated to cost US$1.6
| billion,[102] but the cost estimate grew throughout the early
| development and had reached about US$5 billion by the time
| the mission was formally confirmed for construction start in
| 2008.
|
| So yes, it has been over budget, but by 2x-3x, not 20x, and
| that isn't adjusted for inflation.
|
| Also, everything is just a money pit until it's
| launched/finished/etc.
| tomschlick wrote:
| According to the budget table, when the project started in
| 1997, the budget plan was 500 million. Today its close to
| 10 billion.
| omgwtfbyobbq wrote:
| That was likely just a bare bones estimate and closer to
| the costs of initiating the project than the full cost of
| designing, building, and launching a satellite.
|
| Based on this link, NASA hadn't even settled on a
| design/contractor in 1998.
|
| https://esahubble.org/images/opo9820a/
| guerrilla wrote:
| Adjusted for inflation it'd be about $2.5 billion this
| year. So it's almost exactly 2x.
| wolverine876 wrote:
| What basis do you have for blaming government contracting?
| Lots of projects built by lots of organizations are very late
| and over-budget. One difference between government and
| private industry is that the government has the resources and
| motivation to persist - they aren't in it for profit. If this
| was a private company, it may have been canceled long ago as
| unprofitable. Is that a preferable outcome?
|
| In fact, wasn't the JWST built by Northrop Grumman to a great
| extent? Why not blame them?
|
| EDIT: It's hard to criticize government contracting in the
| same context as NASA, which has taken more risks and achieved
| new things far beyond any private organization in history.
| NASA has operations throughout the Solar System, and in
| interstellar space. They are the only organization to put
| humans on the moon - 50 years ago! Can anyone else say
| anything that? SpaceX?
| minikites wrote:
| Where are all of the privately funded space telescopes?
| sp332 wrote:
| Pointed at earth.
| gamblor956 wrote:
| The original budget was a guess. They didn't know how much
| the telescope would cost because the required technology
| didn't actually exist at the start of the budgeting process
| 24 years ago.
|
| Now that technology does exist, and it turns out it's quite
| expensive, which drove most of the cost increases. However,
| since then the budget increases have generally paced with
| inflation.
|
| Source: your citation.
| DubiousPusher wrote:
| Further to your point, now that the pioneering work has
| been done, a similar piece of equipment could likely be
| built at a significantly reduced cost.
| systemvoltage wrote:
| Another way to put it is that it's a jobs program.
|
| Edit: what's with the downvotes? I would like to understand
| what the disagreement is here. Any gov program can be split
| up into two parts. One, the actual cost as dictated by the
| market economy, and second, the additional costs for delays,
| bureaucracy, etc which usually tends to be multiples of the
| actual costs. This money goes into paying salaries without
| actually making any progress. Hence the jobs program. What's
| there to disagree here? Is this argument somehow belonging to
| a particular political spectrum? Downvotes are fine but I'd
| like to gain some understanding of where my thoughts are not
| aligned with you. Please explain your position.
| DubiousPusher wrote:
| By that logic, so is the military, public schools and
| highway maintenance.
| systemvoltage wrote:
| Any over budget and poorly run government program I see
| it as a jobs program. F-35, CalTrain, NASA SLS, etc.
|
| This is in stark contrast with partnerships with private
| industries. For eg DARPA + Moderna or NASA + SpaceX.
| DubiousPusher wrote:
| I fail to see the difference. Private contracts often go
| over budget. The F-35 itself is full of privately
| contracted parts. Many public/private partnerships
| contracts are even no bid, meaning they are essentially
| uncompetitive. Whether the government hires people
| directly to do a job or whether they contract it out is
| equally distortionary. By allocating tax dollars to a
| public rocket lab or to a private rocket company you are
| increasing the demand for rocket engineers and thus
| creating a "rocket engineer" jobs program.
| wolverine876 wrote:
| All those projects were built by private industry,
| including the latter two.
| systemvoltage wrote:
| That's true. I concede my point.
| bumby wrote:
| While I am as critical of government overspending as
| anyone, this comparison misses some important nuances.
|
| Let's take the SpaceX example. SpaceX is great in terms
| of pushing innovation. But there would be no SpaceX
| without NASA or other government entities. They need
| those tax dollars (especially early on) to survive. And
| when they lose a government payload, the government takes
| something to the tune of 80% of the loss because they are
| self-insured. This has the effect of SpaceX farming out
| their risk to the government.
|
| But this is one of the areas where the government excels.
| Namely, taking large risks in nascent fields where the
| risk is too big for private companies to balance against
| the benefit by themselves. But the complexities and
| unknowns that create that risk is also the very same
| thing that creates the budget and schedule risk as well.
| Lammy wrote:
| I would say "PR program" more than jobs program. NASA is
| the public face of the DoD/NRO spy satellite tech. Most of
| them are just looking back toward Earth at you and I
| instead of looking out into space. Compare to these
| programs which had over 4x the budget of JWST in 2004:
| https://en.wikipedia.org/wiki/Key_Hole
|
| e: For example, KH-11 shares parts with the Hubble Space
| Telescope: https://en.wikipedia.org/wiki/KH-11_Kennen
|
| 'KH-11s are believed to resemble the Hubble Space Telescope
| in size and shape, as the satellites were shipped in
| similar containers. Their length is believed to be 19.5
| meters, with a diameter of up to 3 meters.[5][23] A NASA
| history of the Hubble,[24] in discussing the reasons for
| switching from a 3-meter main mirror to a 2.4-meter design,
| states: "In addition, changing to a 2.4-meter mirror would
| lessen fabrication costs by using manufacturing
| technologies developed for military spy satellites.'
|
| Notice how that says KH-11 _s_ , plural.
| frakkingcylons wrote:
| Your comment doesn't add anything to the conversation. But
| for anyone else that is actually interested: the cost of JWST
| is really not that extravagant considering how much more
| capability it provides compared to HST.
|
| > Not even including its four space-shuttle servicing
| missions, Hubble cost $4 billion or $5 billion in today's
| dollars just to build and launch," Dressler notes. "Here we
| are, building a telescope that is almost seven times bigger,
| it is cryogenic, it is operating 1.5 million kilometres away,
| and it is costing the same amount as Hubble did, if not less.
| That is remarkable, and this is probably the biggest scale on
| which we will consider building such things in this country."
|
| From this article: https://www.nature.com/articles/4671028a
| ufmace wrote:
| The thing with this kind of project, we're not punching out
| the 10 millionth Honda Civic or something. There's a
| tremendous amount of stuff here that's never been done
| before. There's no good way to have an accurate estimate for
| how much it will cost. You pretty much have to just keep
| spending until you get it right. This works the same way
| whether it's Government or Private Industry. Just ask Intel
| how far over budget they've gone getting EUV working.
| systemvoltage wrote:
| It blows my mind that humans can get together and build
| something like this.
|
| I was just watching YT channel "Primitive Technology" and it
| really puts things into perspective. From sticks and stones to
| bootstrapping a James Webb Telescope that's gonna sit at a
| langrange point between the Earth and the Sun. Woah.
| swader999 wrote:
| Interesting angle and this telescope really is a time
| machine.
| slownews45 wrote:
| Does anyone remember the initial proposals for this. The cost was
| supposed to be $500M. At most something like $1B.
|
| Given this is standard govt contracting - I'm sure it's come out
| much higher.
| ProAm wrote:
| Wait until you see what they claimed the Iraq and Afghanistan
| wars were supposed to cost....
| redisman wrote:
| And what the ROI is. Tens (hundreds?) of thousands of dead
| people and stalling the taliban for a little bit versus
| unlocking mysteries into the origins of the universe
| Jabbles wrote:
| Here is a nice table with the history of the budget:
|
| https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Cos...
| slownews45 wrote:
| Clicking through we get this
|
| "JWST is now estimated to cost approximately $9.7 billion and
| launch in October 2021, which represents cost growth of 95
| percent and 88 months of schedule delays since the project's
| cost and schedule baselines were first established in 2009."
|
| So around $10B. Amazing.
| elihu wrote:
| I wonder what the marginal cost would be to build a second
| one?
| swarnie_ wrote:
| Fact boy covered it a few weeks ago:
|
| https://www.youtube.com/watch?v=CowU0QK0Pjs&ab_channel=Megap...
|
| From what i remember this project has been running since around
| the time of Hubble
|
| Still.... Can't wait for it to get up there, money and time
| well spent!
| slownews45 wrote:
| That's pretty amazing. A financial black hole.
|
| A cool project, but if you think of the thousands of folks
| who didn't get funding so this thing could gobble everything
| up - these projects really become crazy budget wise (SLS did
| the same path).
|
| I wish they would do pay for performance deals. We'll give
| you $4B if you put a telescope in space of X size that meets
| some basic specs.
|
| If you look at commercial side, space imaging (earth facing)
| has just exploded and the cost side has gotten very very
| good. So it's clear you can get optics and sensing into space
| for a lot less.
| redisman wrote:
| This is the strength of NASA. They can do crazy one offs
| rather than having to build financially feasible platforms
| all the time
| swarnie_ wrote:
| 10bn in the scope of this joint project between the US,
| Europe and one other group (Canada or Japan?) is a rounding
| error over 20 years.
| hypertele-Xii wrote:
| If you thought estimating software projects was hard, try
| estimating a friggin space launch.
| nickik wrote:
| $1B? That gone last a year tops.
| OrvalWintermute wrote:
| Even 5B for a novel, and uniquely powerful observation platform
| would be a bargain!
|
| When you are engineering a unit of 1 pushing the boundaries of
| science, with multiple conflicting constraints, funded by a
| variety of self-interested stakeholders, and are forced to do
| commercial production, rather than govt production, even when
| it is most cost effective, it isn't like you are heading
| towards lowest cost, technically acceptable.
| slownews45 wrote:
| You can get a pretty good idea of quality of project
| management based on how well or poorly they estimated project
| baseline costs at outset.
|
| These are linked - incompetence in estimating costs /
| complexity = incompetence in execution = insane cost
| overruns.
|
| And you would get far more science with 5 $2B projects then
| one project like this. And if this thing has a launch of
| deployment problem all eggs in one basket. If there are cost
| overruns and delays, also all eggs in a basket and no other
| options.
| marcusverus wrote:
| It's easy to throw these big numbers around, but do you ever
| stop to consider the actual cost? Let's do some back-of-the
| envelope calculations to help us consider the human cost of a
| 5B telescope.
|
| The Median US household income is ~68,000/year[0] The Average
| income tax paid by someone in the 50-75K income range is
| $4,600/year.[1] The average working career is probably around
| 40 years.
|
| 5,000,000,000 / 4,600 / 40 = 27,173
|
| To fund a $5B project, 27,173 people (more, actually, since
| this is household data) could have worked _for their entire
| working lives_ , with every dime of federal income tax being
| spent on that one project!
|
| I agree that the JWST is a worthwhile project, but let's not
| pretend that it's a bargain.
|
| [0]https://www.census.gov/library/publications/2020/demo/p60-
| 27... [1]https://www.fool.com/taxes/how-much-does-the-
| average-america...
| lapetitejort wrote:
| Using the same numbers, 3,824,456 people worked their
| entire lives to fund the USA's military for 2021.
|
| https://www.defense.gov/Newsroom/Releases/Release/Article/2
| 6...
| OrvalWintermute wrote:
| I think that NASA's budget, unlike many other federal
| agencies, is actually highly beneficial to US Taxpayers due
| to the large amount of IP/new inventions generated. Similar
| to DARPA, there are huge ROI factors that come in from an
| organization that researches, conducts science and
| engineering efforts on a massive scale, resulting in
| technologies that consumers can use economically.
|
| https://en.wikipedia.org/wiki/NASA_spinoff_technologies
|
| NASA's budget is one of the smallest slices of the federal
| budget, and for that amount we receive a great deal back in
| benefits.
|
| https://en.wikipedia.org/wiki/Budget_of_NASA
|
| Due to the huge amount of technologies generated, and
| refined from these large prestige missions, I do not
| consider them to be a waste of funding.
|
| One great example are the weather satellites generated by
| the NASA/NOAA partnership, such as GOES-R, and JPSS, and
| their predecessor missions in GOES & POES, to name a few.
| While they are very expensive they equip meteorologists
| with the rich data needed to make accurate observations.
| These observations directly impact human life, both by
| guiding evacuation decisions, knowing tornado tracks, and
| also, farming decisions. This same data is used for supply
| chain management, and there are a number of other uses for
| it.
|
| Although many commercial media sources will be happy to
| provide you a weather feed, they often do not tell you that
| they have a backend connection to NASA, NESDIS and NWS, in
| order to provide their own weather data, or data from a
| research satellite. Or they'll provide you a customized
| photo which is actually a tailored version of imagery from
| GOES-*.
|
| Because of the incalculable costs of an earth impacting
| asteroid, or a Carrington-dwarfing electromagnetic storm
| https://en.wikipedia.org/wiki/Carrington_Event , outward
| looking to see more of the cosmos is one of the best things
| we can do to ensure our survival as a species. The more we
| look out, the more we are able to prepare for such an
| event.
| RaiausderDose wrote:
| please don't blow up and deploy successful in space
| canadianfella wrote:
| Punctuation has a purpose.
| sonograph wrote:
| I remember getting excited about this telescope a decade ago. I
| haven't heard of it since; but I thought it's budget was cut and
| it was over.
|
| I'm excited NASA is finally going to get it up in space!
| darkwater wrote:
| It's ESA that's getting it up into space, NASA is "just"
| collaborating.
| [deleted]
| pkaye wrote:
| Actually the budget was overrun quite a bit. I think it will
| cost $10B at this point.
| keanebean86 wrote:
| $9.5 billion over is pocket change! If you adjust for
| inflation $10 billion is only $7.7 billion in 2007 dollars.
| Assuming the telescope works I can live with it being
| expensive.
| mtdewcmu wrote:
| Unlike the F-35, I think the taxpayers are getting their
| money's worth.
| bumby wrote:
| Unfortunately, I think it's easier to fund something like
| the F-35 because it can be framed as a way to avoid an
| existential threat. It's difficult to do the same with
| fundamental science
| abz10 wrote:
| The F-35 was framed as a way to save money.
| bumby wrote:
| That argument only holds because it was purported to
| replace different weapons systems that were needed for
| mitigating a threat. The threat is the primary motivation
| and cost reduction is secondary. I.e., if not but for the
| existential threat there's no need for the JSF or any
| system it would replace.
| abz10 wrote:
| The F-22 was sufficient for threat mitigation. The F-35
| raison d'etre was cost reduction, after that was
| exportability which again was supposed to help with cost
| reduction.
|
| Edit; comparing the logic of a 'but for' vs a 'necessary'
| condition. Was the F-35 necessary for threat mitigation.
| No. Was it framed as the necessary for cost savings, yes.
| Retric wrote:
| Their designed for slightly different roles. The F-35's
| R&D looks hard to justify vs simply having more F-22, but
| the F-35B can do verticals takeoff for example and the
| F-22 can't.
|
| So, the real question is if the F-35's should have had
| fewer versions and thus been more capable in it's
| remaining roles.
| bumby wrote:
| There's similar analogies here to the space shuttle.
|
| For the shuttle to get approved, it had to meet the
| demands of many masters. The fact that it had to meet DoD
| missions as well as NASA missions made it a bit of a
| boondoggle. Likewise, the JSF needed to meet the Marine
| Corps demands of VTOL to take the place of the AV8B.
|
| It's hard to remain focused when you have so many
| stakeholders. As the saying goes, a camel is a horse
| designed by committee.
| GekkePrutser wrote:
| The space shuttle wasn't as bad as its reputation though.
| Both accidents had organizational causes and were
| entirely avoidable. And its huge payload bay and the fact
| it was a mobile base allowed for the construction of the
| ISS.
|
| It just failed at reusability, it was more like
| refurbishability :) But many lessons have been learned
| from that.
| bumby wrote:
| I'm speaking more to the shuttle cost overruns, both in
| design and mission. I'd argue that the reusability aspect
| was central to the idea of a "shuttle" and if it failed
| at that, it missed its mark.
|
| I agree 100% that there are organizational causes to past
| mishaps. As to whether or not it was avoidable...I tend
| to think they are rooted very much in human psychology
| and we think about risk. The same issues occur today
| within NASA (EVA 23 is a good example [1], despite the
| 'organizational' fixes put in place after _Challenger_
| and _Columbia_ ). Humans are really, really good at
| rationalizing the answer we emotionally want.
|
| [1] https://www.nasa.gov/sites/default/files/files/Hansen
| _PressC...
| Pokepokalypse wrote:
| F-22 theoretically can do a vertical take off as well.
| (not landing).
| bumby wrote:
| It has a thrust-to-weight ratio > 1, but it can't really
| take off vertically in the same sense as the AV8B or the
| JSF. The F22 still needs some appreciable runway so it's
| really a "short takeoff". I think the thrust vectoring
| maxes out around 25 degrees, where the JSF can be
| configured to 90 degrees.
| bumby wrote:
| > _Was the F-35 necessary for threat mitigation. No. Was
| it framed as the necessary for cost savings, yes._
|
| I think we're saying the same thing. The argument is,
| "Was the F22/F18/Fwhatever/weapon-system necessary for
| threat mitigation? Yes."
|
| With that said, if proponents of the F35 want to frame it
| as "threat reduction + cost savings" that's how they get
| the budget approved. But the point stands that without a
| threat, there's no basis for the cost savings argument.
| I'm not saying it was effective as cost reduction.
|
| To circle back to the original point, it's much easier to
| get a budget approved when the basis is existential
| threat, rather than "science is cool."
| abz10 wrote:
| I don't think it's a great example of using existential
| threat for sales, when the whole thing was sold as a cost
| saving. Pretty much everyone at the time just wanted more
| F-22s. I was a technical advisor on the project.
| bumby wrote:
| > _I don't think it's a great example of using
| existential threat for sales, when the whole thing was
| sold as a cost saving._
|
| Again, if there is no threat (perceived or real), there
| is no need for a weapons system, period. Think of it this
| way, if there was a proposal for a cost savings for an
| anti-spacecraft/anti-asteroid system mounted to the JWST?
| I'm saying no, because there is no credible threat that
| would prevent. You need the threat first, in order for
| the cost savings of a program to have meaning if the
| basis of the program is threat mitigation.
|
| > _Pretty much everyone at the time just wanted more
| F-22s_
|
| Not really, unless you're only talking about a specific
| branch. Only the Air Force wanted F22s. As was stated by
| another commenter, the JSF was needed because it was
| because it fulfilled desires that other services had that
| the F22 does not provide.
| abz10 wrote:
| Threat mitigation is largely nuclear shield; but if
| you're taking about maintaining air superiority then the
| F-22 is where it is at. The Navy carrier fleets and
| Marines are force projection.
|
| The JSF were sold around cost savings; half the price so
| you could buy twice as many.
| bumby wrote:
| I think you're taking a very narrow definition of what a
| threat means to make your point. To a Marine in
| Afghanistan, the threat was not mitigated by a nuclear
| arsenal. To them, close air support from a
| technologically inferior aircraft like the A10 did a
| better job of eliminating a threat than the F22 in many
| instances. To the original point, this is why it became
| difficult to retire the old plane despite the JSF and
| F22. It could be tied to a specific threat, and that
| meant it was politically much easier to defend keeping it
| around even if the business case was that it costs too
| much money. At the end of the day, politically defending
| a budget is much easier if it can be concretely tied to a
| credible risk.
| dragonwriter wrote:
| > Pretty much everyone at the time just wanted more F-22s
|
| The Navy and Marine Corps didn't, especially after
| development of the Naval variant of the F-22 was
| cancelled in 1991.
| abz10 wrote:
| I'm sure the Navy wished it wasn't canceled, and the
| Marines probably would have been happy with Harriers.
|
| The stealth window of usefulness is closing anyway with
| improved radar.
| dragonwriter wrote:
| > I'm sure the Navy wished it wasn't canceled
|
| It was canceled because the Navy said it wouldn't work,
| both because of cost and take-off weight of the proposed
| Naval variant relative to the capacity of then-current
| and in-development carriers.
| jasonwatkinspdx wrote:
| Your oversimplifying and missing a lot. The F-35 is not a
| replacement or substitute for the F-22.
|
| The F-22 is an air superiority fighter. The F-35 is a
| multi role strike aircraft. The F-22 would _never_ be
| allowed for export, because it has features we don 't
| want to share even with allies. The F-35 was designed for
| export to allies from day one.
|
| There's no scenario where just buying more F-22's made
| more sense than building the F-35. The F-35's project
| problems, primarily driven from the joint acquisition
| strategy are their own thing, completely independent of
| the F-22.
| XorNot wrote:
| The F-35's problems as I understand it stem principally
| from the Navy wanting a VTOL craft. That whole system
| seems to be front and center when "stuff not working"
| comes up.
| jasonwatkinspdx wrote:
| Marines not Navy, though they're a sub org of the Navy so
| a reasonable thing to say.
|
| There's a Rand study on it. They concluded that the
| attempts at commonality didn't just fail, they proved
| counterproductive. They did a historical review of joint
| acquisition programs and found basically all of them hit
| the same flaw. As appealing as it may seem to congress,
| it's a bad strategy.
|
| The F-35's problems as far as budget and schedule
| slippage were largely in the software section, and a lot
| of that goes back to structuring it as a single source
| cost plus contract. That incentivized LM to make the
| project as big and delayed as possible.
|
| LM is infamous for this sort of thing. They turned Aegis
| into a clown circus of a billion different ship specific
| variants where they could charge N times to fix the same
| flaw in different nearly identical codebases. The Navy
| has been trying to extract themselves from it for like 2
| decades now, with some signs of success finally showing
| up.
|
| In short, LM is behaving in bad faith. This is
| unsurprising. They basically invented these tactics some
| decades back.
|
| Back when Ash Carter was Sec Def, he called in LM and
| demanded they start hitting the promised numbers on
| marginal airframe costs. Reportedly the conversation went
| something like "do this or we'll curtail our buy" to
| which LM responded "by how much?" As replied "how about
| none?"
|
| Suddenly they started hitting the numbers, surprise
| surprise.
|
| We're about to have the same conversation about
| sustainment costs. I hope Austin drives as hard a
| bargain.
|
| If you've read any of the limited info coming out about
| some of the AF's new projects like the B-21 or NGAD, it's
| pretty clear they took the lessons from the F-35 to heart
| and are using a very different approach, one where they
| hold the reigns of integration and can create competition
| at any time.
| Pokepokalypse wrote:
| So was STS (Space Shuttle). . .
| justshowpost wrote:
| Yes, if you prefer eye candy photos to public safety. By
| the way will James Webb wield a modern eye candy capable
| sensor? Not sure about that.
|
| There is few worth from remote sensing unreachable (even
| in theory) objects. Kepler already proved theoretized
| Goldilocks Zone rocky planets and, in general, provided a
| lot of data for non-field research (less exciting than
| Hubble photos indeed). Last, but not least, what's the
| JWST's mission exactly?
|
| Also, from taxpayers' money perspective Kepler's
| component quality was complete disaster.
|
| So, I'd better invest in more Martian/Jovian probes than
| in revival of obsoleted project. Such revival is very
| similar to Russian GLONASS (a competitor to 1970s
| NAVSTAR) programme reboot.
| eganist wrote:
| I hate how shortsighted these comments tend to be, but I
| can understand them.
|
| The money for projects like this, largely due to the
| sensitive nature of it all, still ends up staying local
| to the governments funding the projects, which means a
| significant minority of it still gets recouped in taxes
| two or three degrees down, and the balance that can't be
| recouped still ends up funding colossal technological
| advances, e.g advances in EM sensors, lensing, computing,
| electronic resiliency, power generation, the list goes
| on.
|
| The reason governments spend on projects like this
| regardless of public opinion is because they're necessary
| to advance the state of science and engineeeing when
| investment returns are out of the question near-term.
|
| Even defense spending operates this way, though the
| degree to which we pour good money after bad in defense
| is probably worth scrutiny. At least JWST will bring
| value, unlike the f35.
| justshowpost wrote:
| Well, all the tech advances brought by doing R&D of JWST
| happened already ~15 years ago and already are at the
| market. But its just the same thing as with R&D done for
| F-35. With notable exception F-35's R&D is still work in
| progress because of upgrades, while JWST will remain a
| piece of late 2000s tech to be taken out of the attic in
| early 2020.
| whatshisface wrote:
| The JWST's mission is to see deep infared, which can pass
| through interstellar clouds. It will uncover things that
| have been veiled to us since the beginning of history. It
| can only be built as a space telescope because the
| frequency of its intended observations are so low that to
| a device sensitive to them, air radiates light of
| blinding intensity.
| RapidFire wrote:
| Thanks for this comment; that's a fascinating bit of
| information.
| justshowpost wrote:
| But that was just like saying what _F-35 's mission is to
| fly high in the skies_, sorry.
|
| This sort of proves my point, no one knows which exactly
| research JWST will do upon deployment, because original
| mission goals mainly became obsolete.
| mhio wrote:
| There is a long list of scientists that know exactly what
| research they are doing on JWST down to the minute [0]
|
| For example, Dr Christine Chen et al will be using JWST
| for at least 34.9 hours to study the Icy Kuiper Belts in
| Exoplanetary Systems using near infrared spectroscopy [1]
|
| [0] https://www.stsci.edu/jwst/science-
| execution/approved-progra...
|
| [1] https://www.stsci.edu/jwst/phase2-public/1563.pdf
| [deleted]
| Rebelgecko wrote:
| >This sort of proves my point, no one knows which exactly
| research JWST will do upon deployment
|
| The research isn't a secret, JWST is already booked solid
| for like 18 months after it launches. You can see how
| that time is allocated across various projects here:
| https://www.stsci.edu/jwst/science-execution/approved-
| progra...
| sawjet wrote:
| All those European tax payers are certainly getting their
| money's worth
| arp242 wrote:
| It's roughly the same costs as Hubble ($9.3 billion in 2020
| USD), and that excludes the costs for the mirror correction
| they had to do.
|
| It seems clear the original estimate of $500 million was
| overly optimistic; actually, it was criticized almost
| immediately as such after publication. There's a lot of
| incentive to low-ball these initial cost estimates.
| callesgg wrote:
| I bet it will fail to deploy properly. But I hope not.
| [deleted]
| bane wrote:
| It's my personal belief that these massive R&D space telescope
| programs are nearing their end. Computational approaches among
| multiple sensors, combined with good 'ol factory mass
| manufacturing powered by low-cost reusable launch technology
| allows for the money spent on one-shot programs like this to be
| spent and allocated in radical different ways.
|
| Instead of building one huge short life-span spacecraft, why not
| launch hundreds or thousands of lower cost, less capable birds
| incrementally? You can start with a small "first light" capable
| instrument with a dozen or so spacecraft, then over time and more
| launches put up more and more capability and decommission failed
| or low capability pieces.
|
| Use some computational methods to combine the sensor collection
| from dozens, hundreds, or thousands of these kinds of spacecraft
| and you could end up with planet sized instruments pretty
| efficiently.
|
| By eliminating lots of the hard engineering for the massive
| instruments (like serviceability, difficult to make massive
| mirrors, etc) you can build even better instruments that are
| generational and relatively inexpensive.
|
| You get a more flexible funding story as well, e.g. fund at
| maintenance levels during difficult economic times and fund at
| larger amounts during boom times with matching launch schedules.
|
| Tasking the fleet could be more dynamic as well, with different
| researchers able to reserve different percentages of a huge fleet
| for their specific experiments and needs -- e.g. reserve a
| hundred spacecraft for a long dwell "deep field" type
| observation, or reserve thousands for planetary imaging in a
| nearby solar system.
|
| I know there are naysayers about this who think it's improbable.
| I urge those to think about the Starlink fleet, which went from
| zero birds in the air in 2015 to over 1500 spacecraft today. Now
| instead of radio antenna, what if they had imaging sensors and
| were turned to face out? SpaceX certainly didn't spend anywhere
| near what JWST ran as a program to reach this point and the
| development time has been a fraction so far.
| dreamcompiler wrote:
| > Use some computational methods to combine the sensor
| collection from dozens, hundreds, or thousands of these kinds
| of spacecraft and you could end up with planet sized
| instruments pretty efficiently.
|
| This kind of thing cannot currently be done at optical
| wavelengths no matter how much computational power you throw at
| it; the frequencies are simply too high to do phase capture and
| syncing digitally.
|
| It's done on a limited basis at the very large telescope (VLT)
| in Chile but the phase combiners there are optical and analog.
| techdragon wrote:
| I'm building this! Minus the "computational methods" magic...
| Because as someone has already commented, there are significant
| issues with just merging the telescope data together with
| computational magic.
|
| With the advent of SpaceX's Starship providing a 100% (and the
| 100% is crucial to the economics of this project) reusability
| there is significant potential to reduce many of the costs that
| normally increase the price of a satellite. From not throwing
| away a $10,000 PPOD (cubesat deployer) to the myriad cost
| savings available when you know the next flight is cheap and
| you don't need to buy a $500 part, where a $50 or even $5 part
| would do the job, due to the different risk profile in many
| smaller satellites, compared to a few larger ones.
|
| > Instead of building one huge short life-span spacecraft, why
| not launch hundreds or thousands of lower cost, less capable
| birds incrementally? You can start with a small "first light"
| capable instrument with a dozen or so spacecraft, then over
| time and more launches put up more and more capability and
| decommission failed or low capability pieces.
|
| Thats the basic plan in a nutshell. Start small, build up, from
| the ~10cm primary mirror "phase one" prototypes, to eventually
| using ~50cm primary mirrors. Steady progress using a
| standardised telescope "chassis" for each generation, with each
| having a specific camera/instrument rather than the common (for
| space telescopes) practice of having complicated multi-
| instrument optical pathways.
|
| Think Planet Labs, but facing out at the universe, not down
| towards the ground, and a non-profit/charity not a commercial
| company.
|
| I'll spare the whole spiel that I've regurgitated into grant
| proposals (space costs money and it would be nice if I didn't
| have to pay the entire $250,000 or more out of my own pay-check
| over the course of a decade) if you want to know more (or just
| talk about it, or offer to help, or whatever else at all) you
| can contact me directly (email in my HN profile) or wait till I
| publish the eventual website later this year, I'll be sure to
| post a Show HN once I have pretty pictures of hardware.
| mustardgreen wrote:
| The Starlink fleet has been a huge problem for the field of
| astronomy entirely do to this "move fast and break things"
| ethos.
| nine_k wrote:
| As already said, the problem is in coordination of multiple
| telescopes in spacetime.
|
| It might be better to build one giant telescope piecemeal, by
| adding more and more small mirrors. A similar approach is taken
| by several terrestrial telescopes.
|
| It would still be very interesting to have a few space
| telescopes distributed across the Solar system, much wider than
| the Earth orbit. It could give a sort of stereoscopic picture
| of closest star systems, even though "simultaneous" observation
| would be ill-defined for them.
| imglorp wrote:
| Actually, pulsars can be used for timing and position, and
| all telescopes in your fleet could have sight of the same
| ones. It's probably far easier to do interferometry if you
| don't have atmospheric distortion to deal with.
| Rebelgecko wrote:
| OTOH it's much harder to do interferometry when you aren't
| able to sit on the ground and be stable: your refrigeration
| units can't be located somewhere far away to reduce
| vibration, and you can't stationkeep with nanometer
| accuracy (which may or may not matter depending on your
| frequency- in the past space based interferometry has
| usually only been practical for very long wavelengths)
| nine_k wrote:
| Accordung to the theory of relativity, there's no such
| thing as "the same moment" between two distant bodies. When
| the distance is light milliseconds, we can pretend it does
| not exist. When it is light-seconds, like between Earth and
| GEO, it becomes hard to ignore. With many light hours which
| would separate the telescopes I was talking about, the idea
| of "the same moment" just becomes nonsensical, even in very
| approximate household terms.
|
| Such telescopes could, of course, register the same compact
| body, like an exoplanet, and then their pictures could be
| put together on one timeline, the planet's, thus
| synchronized.
|
| Maybe if a pulsar happens to be close (in angular terms) to
| the object observed, it could help synchronize the
| pictures. If the pulsar lies in a seriously different
| direction, it likely would be less helpful: most pulsars
| have rather short periods, and all pulses are the same.
| arp242 wrote:
| Deploying multiple smaller telescopes was one of the designs
| that was considered in the 90s for what eventually became the
| JWT.
|
| I'm not an expert on any of this, and I don't know specifically
| why it was rejected, but it's not like people aren't thinking
| about all sorts of possibilities. Usually there's a reason
| they're not being done though.
| [deleted]
| skhr0680 wrote:
| Phone cameras show both the power and limits of computational
| photography. You can't run away from physics forever.
| whoisburbansky wrote:
| Phone cameras don't have multiple lenses working together
| that you can interpolate between to create a single giant
| virtual lens. The technique OP is referring to is already
| used for the largest ground based radio telescopes.
| bane wrote:
| Exactly correct. And Labeyrie has a design in place for the
| exact type of fleet I'm talking about.
| mhio wrote:
| Do you have a link to the design? I'm assuming it's a
| radio telescope?
| PabloRobles wrote:
| Not the OP, but I guess he is talking about the
| hypertelescope concept:
| https://hypertelescope.org/hypertelescope-en/
|
| For additional background, there are already optical
| interferometry telescopes in use, see VLTI by the
| European Southern Observatory (Chile, shared facility
| with the four VLT telescopes and some smaller
| telescopes).
| bane wrote:
| No the design is optical. Here's a white paper on the
| concept. https://www.google.com/url?sa=t&source=web&rct=j
| &url=https:/...
|
| Labeyrie has also proposed a fleet in L2 and on the Moon.
| jagger27 wrote:
| Well, a lot of phones do have multiple sensors and lenses.
| For example, the iPhone's computational depth effect uses
| multiple cameras for a single shot.
| whoisburbansky wrote:
| That's qualitatively different from the kind of stitching
| together that happens with, e.g. the VLA. The
| computational limits of phone photography don't apply
| here.
| gpt5 wrote:
| Even if this computational photography vision is years away,
| JWST might still become obsolete quickly.
|
| SpaceX's Starship would be able carry telescopes than JWST as a
| single piece. This would dramatically simplify development and
| increase optical quality.
| manquer wrote:
| The challenges in building a mirror that size is enormous and
| take years.
|
| It is not only fairing size that is limiting
| gnarbarian wrote:
| why not build the mirror in space? I bet microgravity could
| help with some of the challenges of building one.
| manquer wrote:
| It is going to take long while to build infrastructure to
| support any kind of construction let alone high tech
| construction like this.
|
| Also I don't know if there actual benefits in doing
| mirror construction in low gravity
| boardwaalk wrote:
| Wouldn't land-based telescopes already use larger mirrors
| than any space telescope?
| marcyb5st wrote:
| Yes they do, but you have to consider the problems that
| the atmosphere poses. A lot of the budget for ground
| telescopes goes into the adaptive optics (actuators that
| can deform the mirror to compensate for distortions due
| to non-uniform column of air above the telescope). For
| adaptive optics to be effective you need bigger mirrors
| because you can't deform a small mirror enough to counter
| that.
|
| Additionally, the atmosphere blocks a bunch of
| wavelengths that are really interesting to observe [1] so
| we still want to be in space for these observations.
|
| Finally, in the non distant future I believe space
| telescopes will ditch mirrors altogether. For instance,
| the proposed Aragoscope [2] would use diffraction optics
| instead of so called geometric optics (lenses, mirrors)
| to focus light. Since the material that can provide the
| diffraction can be anything it would be much cheaper to
| launch a sheet of <insert light and bendy material here>
| that can unfold once in space instead of incredibly
| precise and fragile mirrors. Also, according to Nasa,
| this approach can achieve ~1000 time the resolution of
| HST at a fraction of the price and we are only limited by
| the size of the disk creating the diffraction.
|
| [1] https://www.researchgate.net/figure/The-atmospheric-
| transmis... .
|
| [2] https://www.nasa.gov/content/the-aragoscope-ultra-
| high-resol... .
| zaarn wrote:
| Can you launch those mirrors into space on a rocket
| without them turning into very fine glass dust? Cuz I bet
| a lot of mirrors in land-based telescopes would simply
| shatter or break on a launch.
| boardwaalk wrote:
| Haven't a clue. It's an interesting question. What kind
| of materials they're made out of (weight
| considerations?), what kind of forces they can take, what
| kind of support structures they require, etc.
| wolverine876 wrote:
| Could you back that up with anything? There is so much
| excitement about SpaceX, it seems like all I read about on
| HN.
| simonh wrote:
| Saul Perlmutter is a Nobel Prize winning astrophysicist and
| has been talking about doing this.
|
| https://twitter.com/ChrisG_NSF/status/1412845923521204237?r
| e...
| nullifidian wrote:
| https://www.youtube.com/watch?v=kEECPKLHwl8 https://en.wikipe
| dia.org/wiki/Large_strategic_science_missio...
|
| They are already planning telescopes using Starship's
| capabilities, and one of these telescopes has a mirror that
| consists of several segments, albeit not hexagonal and is
| pre-assembled. The telescope is being touted as an overall
| cheaper solution due to the diameter that Starship could
| carry. But there is also a telescope that is an enlarged
| version of JSWT.
|
| JWST is probably a required stepping stone for these future
| telescopes.
| mhio wrote:
| I doubt the large space telescope programs will end, there will
| just be other options to how they're done. Scientists will
| still push the state of the art (if they get the funding) which
| will still be expensive and might still involve big mirrors
| here and there for optical imaging. Building a large fleet
| radio telescope in space actually sounds like a good proposal
| for massive R&D space telescope program.
|
| Unfortunately optical interferometry as suggested isn't a thing
| yet. Even the physical optical interferometry we do on the
| ground has only become possible relatively recently. I'm not in
| the field so I'm not sure what's around the corner but seems to
| rule out Hubble/JWST/WFIRST/LUVOIRE replacements any time soon.
| Maybe TESS like scanning imaging would be a good fit for a
| fleet?
|
| The big change I hope will be easier, cheaper, regular access
| to space which hopefully means there won't be such unicorn
| projects that spend 4 years in systems testing because they
| _can't_ fail.
|
| > Tasking the fleet could be more dynamic as well, with
| different researchers able to reserve different percentages of
| a huge fleet for their specific experiments and needs
|
| Specific observations require specific instruments though,
| there's no one size fits all fit out for a fleet satellite.
| JWST has a very large mirror looking a near and mid infra red a
| long way from earth with large IR shielding. You can't do this
| and Kepler/Tess type imagery in a single fleet unless the sats
| are specifically equipped for it on the ground before launch
| and sent to vastly different places which kind of nullifies a
| really dynamic fleet.
|
| Not saying that having a standardised, cheap satellite bus that
| can be quickly thrown up in space won't change things, it's
| just not the answer to everything.
| Cacti wrote:
| You need exceedingly accurate timing and transmission to do
| computational inference with multiple telescopes. Even
| minuscule errors will wreck the entire effort. It is very, very
| hard even with only three telescopes on earth, nevermind a
| hundred hurtling around in orbit communicating with lasers.
|
| The people who work on these things aren't morons, and everyone
| knows the scaling factor of multiple receivers. It's just very,
| very hard.
| bane wrote:
| Sure it's hard, bit I'm not really even proposing anything
| new. Labeyrie has proposed such a fleet, but raw economics
| have put it off, not technology -- I'd hardly call him a
| slouch in astronomical interferometry.
| [deleted]
| zabzonk wrote:
| > Instead of building one huge short life-span spacecraft
|
| Short life-span? How long has the Hubble been up there?
| foolfoolz wrote:
| webb needs to use thrusters to stay in position. there's 5
| years worth of fuel onboard
|
| they did design the fuel in a way that potentially could be
| refilled... but the refilling craft doesn't exist. and webb
| timescales make that sound impossible
| Taniwha wrote:
| And it's at L2 so not that easy to get to
| prox wrote:
| I take Starship could, and should be operational in some
| form by then.
| Cthulhu_ wrote:
| Question is whether it'll be financially / commercially
| viable. I think that greatly depends on how much data the
| telescope gathers or whether it needs more time. Also
| keep in mind that the Hubble got multiple upgrades over
| its lifespan, which will be much more difficult with the
| Webb - is it feasible to do spacewalks that far out? Has
| any astronaut ever done a spacewalk outside of Earth
| orbit?
| LargoLasskhyfv wrote:
| Are you referring to the protection by Earths magnetic
| field?
|
| If so, would it matter much, given we (allegedly) shot
| humans in not more than slightly pressurized tin cans to
| the moon multiple times?
|
| And they survived.
| prox wrote:
| Yeah, if it has done it set out to do, then we don't need
| to. Also depends how much of a moon presence we have in
| five years. Launching from the moon might make it
| feasible for sure, considering the billions the JWST has
| cost!
| arp242 wrote:
| According to the NASA website there is fuel for 10 years,
| and the five years is just the "minimal" mission time for
| which it's tested.
|
| https://jwst.nasa.gov/content/about/faqs/faq.html#howlong
| Gustomaximus wrote:
| Question if anyone knows: ~9.5 years any reason to not
| push it out of orbit into space and continue to get
| signals back for years longer as it floats off? Like the
| voyagers?
| arp242 wrote:
| To push it out in to space like Voyager requires a lot of
| thrust, so I bet that's the reason.
|
| As far as I can find, it's kept in the L2 point mainly
| for temperature reasons.
|
| Not an expert, but this is what I gathered from
| https://space.stackexchange.com/q/23238/13952 and
| https://space.stackexchange.com/q/38408/13952
|
| From what I can tell I don't think that it's very
| uncommon that these things are designed for 5-10 year
| missions and that everything else is just a nice bonus. I
| don't think anyone expected Hubble to survive as long as
| it did for example, and even the Voyager program was
| originally designed to be finished in the 80s and I don't
| think anyone expected it would last this long either.
| thereddaikon wrote:
| JWST isn't a probe like Voyager. It's job isn't to go to
| other worlds and see what's there. Its a space
| observatory. It does exactly the same job a telescope on
| earth would do, just in space. The reason why is to avoid
| light pollution and the interference from earth's
| atmosphere.
|
| So that fuel isn't used for going places, its for aiming
| the telescope and keeping it steady. Once the fuel is
| gone it can no longer control where its pointing. If you
| cant aim a telescope then its useless.
| dreamcompiler wrote:
| You can aim it with reaction gyros which rotate the
| telescope and require only electricity. What you cannot
| do with electricity is translate the telescope along a
| vector to compensate for orbital decay and keep it on
| station. That's what fuel is for.
| findalex wrote:
| When you consider how long this thing was in
| development/production, 5 years doesn't seem very long.
| minitoar wrote:
| It's the telescope of Theseus, though.
| xref wrote:
| Because some component bays designed to be swapped out were
| swapped out? Far as I know they haven't replaced the 2.4m
| main mirror or the housing, you know, the "ship"
| minitoar wrote:
| Yes, that is the joke I was making. Thank you for
| explaining it.
| vimacs2 wrote:
| I think their point was your joke doesn't make much sense
| when only a small subsection of the entire telescope was
| ever replaced.
| minitoar wrote:
| In my opinion that's part of what makes it funny, and is
| also a core issue in the Ship of Theseus problem -- who's
| to say how much it can be changed and is still "the same
| thing"? Maybe the thing that was replaced was very small
| but was very important to the identity.
| zabzonk wrote:
| Sort of. The broken optics famously got fixed in the first
| HST shuttle mission, and there have been other replacements
| over time. A lot of it is the same, though.
|
| And of course, the HST is in LEO, which means it is
| reachable with current rocket tech, which the James Webb,
| being situated at L2 won't be. But that's not to say you
| could not have a large platform at L2 (or another Lagrange
| point) that could be serviced by robots, or even manned
| craft, if it was designed that way.
| minitoar wrote:
| I guess my point was: without that servicing it would've
| been a pretty short life span (literally 0?). The swarm
| approach helps with this.
| GekkePrutser wrote:
| But Hubble wasn't a one-off design. It shared a lot of
| design elements with other space telescopes that are more
| earth-focused :) So it had a lot more benefits of scale
| than JWST.
| abhiminator wrote:
| On a related note, I highly, highly recommend watching this well-
| made documentary on JWST, released around 3 and a half years ago
| -- https://www.youtube.com/watch?v=FLD9LKq0u9E
|
| This documentary was produced by Northrop Grumman Corporation --
| the builders of JWST under a NASA contract.
| wolverine876 wrote:
| > This documentary was produced by Northrop Grumman Corporation
| -- the builders of JWST under a NASA contract.
|
| Is it promotional material?
| gccs wrote:
| Propaganda
| vimacs2 wrote:
| Considering that they themselves made the telescope, do you
| consider all forms of self expression propoganda?
| wolverine876 wrote:
| > self expression
|
| This isn't art. And yes, I don't trust corporate press
| releases (though I'm not sure "propaganda" is the right
| term); do you?
| mongol wrote:
| What is it hoped this can see? Is there some specific hypothesis
| this telescope was built to confirm?
| doctoboggan wrote:
| It should be able to detect the atmospheric makeup of expo
| planets (via spectroscopy during a transition). This will let
| scientists search for signs of life on other planets.
| SiempreViernes wrote:
| Hopefully it'll tell us about the period of reionisation, when
| the light of the first galaxies made the universe transparent
| again.
| redisman wrote:
| The oldest galaxies that have red shifted off the spectrum and
| are only visible with this. You can't do IR telescoping except
| at L2 because earth is giving off its own IR reflection or
| radiation or something like that
| sidcool wrote:
| This is one of the most daring missions. In case of any
| malfunction there will be no chance of reparing. Everything has
| to go right
| 908B64B197 wrote:
| Here's the official release from the launch partner
| [0](Arianeespace and the Eeuropean Space Agency are providing the
| launch on an Ariane V rocket).
|
| They are the ones responsible for that milestone of the project
| (NASA and JPL already completed manufacturing of the spacecraft).
|
| Exciting news!
|
| https://www.esa.int/Science_Exploration/Space_Science/Webb/W...
| endymi0n wrote:
| While it's awesome to finally see the JWST finally come to close
| to launch after all those years, now it's a close race between it
| and SpaceX Starship that could have taken the 6.5 meter mirror up
| to space in one whole piece in its 9m diameter belly rather than
| having to do all the miraculous origami that took two decades to
| develop in the first place...
| jasonwatkinspdx wrote:
| While I'm rooting for SpaceX with Starship, lets be clear:
| they're still trying to get hovering grain silo versions
| working. Meanwhile JWT is ready to go. If it's a race one side
| has already won rather emphatically.
| caconym_ wrote:
| Actually, they're well beyond the "grain silos" by now.
| They've successfully demonstrated the "bellyflop" landing
| maneuver from a terminal velocity fall, and now they're
| (credibly) trying to launch a full prototype Starship stack
| to orbit within the next few months.
|
| Wiki says JWST is planned to launch by this November, so I
| think there is a decent chance Starship beats it into space.
| That won't be a production-ready vehicle, and launching
| anything valuable on it (let alone something like the JWST)
| would be certifiable, but let's give credit where it's due.
| jasonwatkinspdx wrote:
| I know where SpaceX is. Elon does have a clear history of
| being overly optimistic about timelines.
|
| There's a _zero_ percent chance they 'll have a vehicle
| ready by the JWT launch date that could launch it instead,
| even if they get to orbit by then.
|
| This is not a race. As I said I'm a SpaceX fan, but I am
| not a fan of every single space topic being derailed by
| "but what about SpaceX?" as if they're the only company
| doing things meaningful in the industry. They're the super
| cool new kid on the block, but there's still a lot more out
| there that doesn't deserve to constantly be lampooned for
| not being SpaceX.
| caconym_ wrote:
| > I know where SpaceX is.
|
| I mean, Musk may be famous for his "optimistic"
| timelines, but you completely misrepresented their
| progress. "Still trying to get hovering grain silo
| versions working" is not remotely accurate.
|
| That's the only point of my previous comment: give credit
| where it's due, as I said. I agree with most or all of
| the other things you've said in this subthread.
| jasonwatkinspdx wrote:
| I am giving credit. I'll call it working when they've
| demonstrated repeated access to orbit. Until they, they
| are indeed playing with flying grain silo prototypes,
| even if they landed one belly flop maneuver.
|
| In any case, this is the exact sort of argument I find
| entirely wasteful of energy, and a distraction from what
| we should be talking about in this thread, which is JWT.
| caconym_ wrote:
| > I am giving credit.
|
| No, you aren't. "Still trying to get hovering grain silo
| versions working" is not an accurate characterization of
| the current state of Starship development: they had
| hovering in the bag months ago, and have since
| demonstrated much more challenging and impressive
| capabilities.
|
| > I'll call it working when they've demonstrated repeated
| access to orbit. Until they, they are indeed playing with
| flying grain silo prototypes, even if they landed one
| belly flop maneuver.
|
| None of this is germane to the problems with your
| original statement. It's just empty snark--if you want to
| call rockets "grain silos", I'm not going to try to stop
| you, though I might caution you against erasing your
| ability to identify actual silos full of grain.
|
| > In any case, this is the exact sort of argument I find
| entirely wasteful of energy, and a distraction from what
| we should be talking about in this thread, which is JWT.
|
| I'm just here to correct the record, which I think is
| reasonable as there's a lot of weird SpaceX
| misinformation out there, both "for" and "against".
| Personally I don't understand why people can't just sit
| back and watch what happens, without putting their own
| spin on it.
| mhio wrote:
| > if you want to call rockets "grain silos", I'm not
| going to try to stop you, though I might caution you
| against erasing your ability to identify actual silos
| full of grain.
|
| Agreed, they're definitely flying water tanks :)
| wolverine876 wrote:
| SpaceX has nothing to do with this. Their rocket has zero
| demonstrated capability for this mission.
| minikites wrote:
| I wouldn't trust any payload on a SpaceX ship given their track
| record.
| relativ575 wrote:
| SpaceX launched three crews to the ISS within the last 12
| months. In other words, they are trusted with payload with
| the highest caliber.
|
| How can a comment be that ignorant yet presented in such a
| confident tone?
| caconym_ wrote:
| Falcon 9 (and Heavy) has not experienced any kind of mission
| failure since 2016, the latter period accounting for (if I'm
| counting right) 69% of its total launches including the
| Amos-6 pad failure (which did not actually launch). Its
| actual failure rate is 1.5%.
|
| It's not a track record that deserves any more derision than
| its contemporaries. Doing so in such vague terms just makes
| you look like you don't know what you're talking about, which
| goes double if you're thinking not of F9, but rather of those
| big shiny rockets they've been blowing up in Boca Chica
| recently. That (Starship) is a development program.
| JoeAltmaier wrote:
| That's how space travel development works. It doesn't take
| off; it crashes; it explodes; it fails to land; it works.
| From then on pretty much, it works.
| wolverine876 wrote:
| What is that based on? How do you distinguish launch
| systems that just don't work well? Everything works in the
| end? That would make engineering much easier and less
| stressful!
| lazide wrote:
| I'm unaware of any launch system that gets many tries at
| failures - it either gets what needs to be done
| relatively quickly or it gets cancelled. The number of
| tries you get is usually single digits.
|
| Everyone fails a few times at a minimum.
| Me1000 wrote:
| The Falcon 9 has had 126 missions so far and only 2 of those
| were failures. It's not a perfect record, but it's pretty
| decent. And presumably SpaceX has learned from those
| failures. Compare that to the Ariane 5 rockets (which will
| actually be launching the James Web Space Telescope) which
| has had 109 launches, and 5 of them ended in failure.
|
| I'm just going to assume you're referring to Starship's
| various explosions. It's far too early in the Starship
| development cycle to draw any kind of conclusions about it's
| reliability.
|
| Starship is a prototype. It's a completely new vehicle with
| completely new engines, and they're building it with the
| expectation that the early versions are going to blow up.
| It's like saying Falcon 9 is unreliable because their early
| "grasshopper" prototype (for testing landing) exploded and at
| times. Also probably a good idea to note that these
| explosions all happened during their landing attempt, so in
| theory any payload onboard would have already been deployed.
| It's just the vehicle that would be lost. Of course they're
| still so early in the development cycle that Starship hasn't
| even attempted an orbital flight yet.
|
| I get that it's weird watching these very early prototypes
| blow up so spectacularly and publicly, but that's the
| development model SpaceX has chosen. And we're not used to
| watching rockets being built and tested so out in the open.
| Personally I think it's exciting watching the progress
| they're making.
| wolverine876 wrote:
| > the Ariane 5 rockets (which will actually be launching
| the James Web Space Telescope) which has had 109 launches,
| and 5 of them ended in failure
|
| I just read that they had one failure, though I can't find
| it. Does anyone have any reliable data (i.e., not
| Wikipedia)?
| mhio wrote:
| http://www.spacelaunchreport.com/ariane5.html
|
| The notes for the failures are at the bottom.
| jl6 wrote:
| If the JWST survives launch but has a subsequent mechanical
| problem that prevents it deploying properly (and it's the kind of
| problem that would have been fixable on Hubble, using a shuttle
| mission) would it be feasible to mount a robotic rescue mission
| to chase it down and remote-hands it back to life? For less than
| the cost of just launching another JWST?
| OrvalWintermute wrote:
| It is conceivable that on-orbit repair missions like OSAM-1
| could fix a mission with a mechanical failure, depending on the
| orbit that it reaches.
|
| https://nexis.gsfc.nasa.gov/osam-1.html
| derekp7 wrote:
| I would think that a cheaper (or multiple cheaper) versions
| could be made if they don't require the long lifespan and
| reliability that previous launch costs inflicted. Once Starship
| is going, and if it proves to be as low cost as the current
| projections, I could see multiple space telescopes being
| designed cheaply for a launch every year, each one designed in
| a narrow configuration that serves a specific purpose. But I
| really don't know what all goes into making a space telescope
| so expensive currently.
| phkahler wrote:
| >> But I really don't know what all goes into making a space
| telescope so expensive currently.
|
| I think you already said it. The long life (high reliability)
| requirement, and I'll add the complexity of having it unfold.
| Both of those become non-issues if you build the telescope
| right into a space-X starship. There may be other issues with
| that, but the mirror wouldn't need to fold ;-)
| bumby wrote:
| Are you speaking to the reliability of the launch vehicle
| or of the satellite? The launch itself is typically not a
| primary cost driver of a satellite mission. Complexity may
| be, due to constraints of the fairings but the
| manufacturing and quality checks drive quite a bit of the
| cost
| ckozlowski wrote:
| I think they mean reliability of the satellite. The JWST
| is going to be parked at a Lagrange point that's going to
| put it out of reach of most everything. At the time it
| was conceived, robotic servicing was even further off. A
| crewed mission was right out. Costs went far up in part
| because unlike Hubble, servicing was going to be
| virtually impossible.
| anticensor wrote:
| Starship has a sufficient delta-v to service it.
| qubitcoder wrote:
| Yes, but Starship is a prototype at the moment. And it'd
| require the Super Heavy to even reach orbit, which will
| soon begin testing [0].
|
| Additionally, the engineering requirements for long-term
| life support are significantly more involved than the
| Dragon capsule.
|
| There's also the testing and certification process for
| crewed-missions; in non-Elon time, this is likely several
| years, conservatively speaking [1]. (I'd love to be
| proven wrong, however!).
|
| [0] https://www.space.com/spacex-starship-super-heavy-
| booster-ro...
|
| [1] https://arstechnica.com/science/2021/04/five-reasons-
| why-nas...
| deepsun wrote:
| Also, all robotic space repair satellites are very into
| military tech (even taking pictures of open space is very
| strictly controlled, because you may inadvertently take a
| picture of a military satellite). Not event talking about
| disabling err.. repairing, de-orbiting, spinning etc other
| satellites. That types of tech is opposed by military, that's
| actually one of the reason we don't clear dangerous space
| garbage (especially considering some of that garbage is
| actually working military satellites).
| NavinF wrote:
| > taking pictures of open space is very strictly controlled,
| because you may inadvertently take a picture of a military
| satellite
|
| Citation needed
| deepsun wrote:
| I worked in a private space company, that I was told by
| SatOps folks. I remember they said only US citizens on US
| territory could process the photos.
| ufmace wrote:
| The trouble with robotic repair missions is that it could work
| pretty well if you knew 100% exactly what was wrong, and
| exactly what else might go wrong while applying the fix for
| whatever went wrong. The more potential unknowns, the harder it
| is. It's much harder to make a robot with enough general
| flexibility that it could probably handle diagnosing and
| repairing an unknown issue, or handle something going wrong
| while trying to carry out a planned repair sequence. Bolts
| jammed, too loose, too tight, tanks of stuff springing leaks,
| electrical short in some unknown place, component overheating
| for unknown reason, all sorts of things can go wrong that are
| tough to diagnose remotely or with a special-purpose robot.
| MayeulC wrote:
| How about deploying it near the ISS?
| nhoughto wrote:
| And you'd need to have it designed to be serviceable once
| deployed. I'd imagine there would be a few assumptions going
| into the design process, "once deployed humans won't ever
| need to get to that.."
| dylan604 wrote:
| Seems to me it would be easier to design a craft to dock with
| it and bring back to an easier for humans to reach location.
| Then push it back out to where it needs to go. I'm sure there's
| some delta-v math to determine the fuel requirements, and I'm
| guessing it would also make a huge difference on how fast you
| wanted it back.
| nabla9 wrote:
| The JWST will not orbit Earth. It will be located near the
| second Lagrange point (L2) over 1,500,000 km away (The Moon is
| just 405,000 km from the Earth).
|
| Space Shuttle could not have reached it.
| wyldfire wrote:
| How long can it stay stable at that point? Does it have
| thrusters to keep a station there? If so, how long is the
| fuel for them provisioned for?
|
| Does use of the thrusters impact the sensors that the
| telescope uses?
| pageandrew wrote:
| The orbit needs to be actively maintained. The telescope
| was designed for a 5.5 year mission, but NASA says it could
| last up to 10.5 years with proper fuel management. It has
| two different types of thrusters under the "Propulsion
| Subsystem".
|
| > One kind is called "Secondary Combustion Augmented
| Thrusters" (SCAT), and they are used for orbit correction
| (like applied changes in velocity for each maneuver the
| spacecraft makes and also for orbit station-keeping). The
| SCATs are bi-propellant thrusters, using hydrazine (N2H4)
| and dinitrogen tetroxide (N2O4) as fuel and oxidizer,
| respectively.
|
| > The other kind of thruster on Webb is called a MRE-1, or
| mono-propellant rocket engine, since it only uses
| hydrazine. There are eight MRE-1s on Webb, and they are
| used for attitude control and momentum unloading of the
| reaction wheels
|
| Ref: https://jwst-docs.stsci.edu/jwst-observatory-
| hardware/jwst-s...
| spywaregorilla wrote:
| > Does use of the thrusters impact the sensors that the
| telescope uses?
|
| The point of sitting in a lagrange point is that you can
| stay there without moving due to two gravitational forces.
| That's not perfectly accurate, but I don't think it needs
| constant thrust, just occasional taps.
| [deleted]
| hguant wrote:
| The L2 point is unstable with a period of 23 days? I
| believe, so the JWT needs a course correct burn to stay
| positioned correctly (called station keeping).
|
| It does have thrusters - a ring of 16 hydrazine "burning"
| units that can produce thrust on 3 axis.
|
| The fact that the L2 point is unstable and that thrusters
| are required puts a lifetime on the telescope - I think
| NASA plans for a minimum of 5 1/2 years and are hoping to
| get up to 10. That's entirely reliant on the fuel supply.
|
| The use of thrusters does impact the sensors the telescope
| uses. NASA et al schedule usable telescope time around
| burns, and general attitude shifts/correction. The
| telescope uses a bunch of gyroscopes/flywheels to point
| itself in the proper direction, during maneuvers like that
| the sensors aren't operable.
| wyldfire wrote:
| > The fact that the L2 point is unstable and that
| thrusters are required puts a lifetime on the telescope -
| I think NASA plans for a minimum of 5 1/2 years and are
| hoping to get up to 10. That's entirely reliant on the
| fuel supply.
|
| So when the fuel is exhausted the orbit decays and the
| unshielded telescope disintegrates on re-entry into
| Earth's atmosphere?
| lmm wrote:
| > So when the fuel is exhausted the orbit decays and the
| unshielded telescope disintegrates on re-entry into
| Earth's atmosphere?
|
| Or drifts off into its own orbit around the Sun, but
| essentially yes.
| pklausler wrote:
| It's not an orbit, per se, but... it will go around the Earth
| once per year.
| phkahler wrote:
| >> it will go around the Earth once per year.
|
| I think more accurately it will go around the sun once per
| year. The earth will provide the extra gravitational pull
| (toward the sun) needed to orbit the sun at a larger radius
| than the earth in the same amount of time as the earth.
| pklausler wrote:
| Sure, but it also goes around the Earth once per year,
| too, sidereally.
| phkahler wrote:
| Sure, but I doubt anyone would say that about some of the
| other lagrange points.
| sp332 wrote:
| It equally orbits the sun and the earth.
|
| Normally, objects with smaller orbits take less time to
| make a circuit. But this is placed where the earth's
| gravity pulls it back, just enough to make it take one
| (earth) year to finish its smaller orbit. So gravity from
| the earth and the sun are involved.
| nabla9 wrote:
| Only in the same sense as mars goes around the Earth.
| Meaningless concept. It never crosses inside Earth orbit.
|
| Maybe "co-orbits the Sun with the Earth using Earth's
| gravity"
| geenew wrote:
| It has a docking clamp, though that's for future-proofing.
| Apparently the initial type of mission envisioned was a crewed
| Orion vehicle, though I'm sure a wide variety of missions
| _could_ attach.
|
| My guess was that the clamp was mainly for possible future
| replenishment of consumables, though presumably some sort of
| robotic-arm-equipped repair mission could attach as well. A
| crewed mission seems possible, too, assuming one of the planned
| Lunar craft could be modified to go to the Lagrange point.
|
| https://www.space.com/3833-nasa-adds-docking-capability-spac...
|
| https://en.wikipedia.org/wiki/Spacecraft_Bus_(JWST)#Docking_...
| imglorp wrote:
| Nothing in the current fleet of new capsules have arms or
| airlocks.
|
| There is hope for the robotic refueling type mission though,
| or at least the kind where a new utility bot attaches to an
| old satellite and takes over propulsion to extend its life.
|
| https://nexis.gsfc.nasa.gov/rrm_refueling_task.html
| messe wrote:
| > Nothing in the current fleet of new capsules have arms or
| airlocks.
|
| True, but a docking adapter with an airlock that works with
| starliner and dragon is _technically_ feasible. That said,
| it would still likely require recertification, as its
| inclusion would effect abort modes.
| Torkel wrote:
| Latency is a bitch. So remote hands from earth is most likely a
| no-go, for this reason alone.
|
| And if you bring astronauts close, then I guess that some EVAs
| in existing suits starts looking appealing vs developing those
| remote hands.
| system2 wrote:
| They wouldn't operating it like they play computer games.
| Mars rover has a major latency too, they can simply instruct
| it with limits and work slightly slower.
| BitwiseFool wrote:
| The JWST orbits out beyond the Moon, so I don't know if the
| Orion capsule and European Service Module even has the Delta-V
| to make it to that Lagrange point and back. Plus, I'm also
| unsure about the life support and duration requirements for
| such a mission.
|
| I imagine the only realistic repair mission would be with a
| Starship crew, seeing as Orion and all the other Commercial
| Crew vehicles would probably require some additional components
| to make it out that far and to sustain their crews. Starship
| seems big enough and far enough along in development to be
| viable.
|
| Edit: The JWST has a docking ring to let Orion service it. But
| I don't know if the SLS in it's available configurations can
| get it up there. It _seems_ like a contingency but I don 't see
| any solid information about an Orion service mission.
| wolverine876 wrote:
| The GP asked about robotic, not human missions.
| BitwiseFool wrote:
| My mind skipped over that. I don't have a good answer for a
| robotic mission but I imagine NASA won't fund it.
| ultramegachurch wrote:
| Highly unlikely. That would require designing a new spacecraft
| from the ground up while also developing new robotics and
| operations technologies. I'd peg that mission at $300 - $500
| million. NASA would almost certainty be better off documenting
| lessons learned and pursuing a new observatory.
| nrdgrrrl wrote:
| They've spent almost 10 billion dollars on this telescope so
| far. What's another 0.5 billion for a repair mission?
| ultramegachurch wrote:
| That 0.5 billion (which to be clear, is a number I made up)
| won't guarantee that JWST will be fixed. The "fixer"
| spacecraft could end up failing itself. Or it could
| discover new problems that it's not equipped to handle.
|
| Also, congress would be extremely critical of NASA if JWST
| fails. They would not be excited to shell out another $0.5
| billion for a chance to fix it.
| vimacs2 wrote:
| Not to mention that we don't even currently have a real
| capability to repair the currently malfunctioning Hubble
| telescope anymore. That was designed for maintenence from
| the now non-existent space shuttle in mind. Trying to
| accomplish the same with the Dragon would be unknown
| territory and it seems that there is little desire from
| both NASA and congress to even bother.
|
| JWST in comparison is a far trickier and complicated
| beast to tinker with. This is the biggest reason why they
| are so paranoid about any fault before orbital launch. It
| would be all but impossible to service it - on both a
| technical and political level.
| mcbutterbunz wrote:
| > I'd peg that mission at $300 - $500 million.
|
| If that was the cost for that mission, it would be worth it
| considering JWST cost about 20x that amount.
| bl5THJUSFXWy4ii wrote:
| You are considering the entire cost of developing the JWST.
| Surely the cost of building another based on the finished
| design would be lower.
| e_y_ wrote:
| I think part of the reason the JWST took so long to build
| was the complexity of the design. As in, it was difficult
| to manufacture and assemble and test due to the way it
| was designed. It might be cheaper to do it a second time
| based on the lessons (avoiding mistakes) from the first,
| but it would probably still be quite expensive.
| _greim_ wrote:
| I wondered the same thing. I once read this commentary on
| project management (disguised as a StarWars fanfic)[1]
| which makes me pessimistic. However I'm in no way
| involved so I'd be curious to hear what someone more
| knowledgable thinks.
|
| https://m.fanfiction.net/s/11685932/1/Instruments-of-
| Destruc...
| spaetzleesser wrote:
| When I look at project management for the small projects (1-20
| people) I am working on I always wonder how projects of such a
| complexity are managed. It must be freakishly difficult to
| coordinate all the pieces.
|
| The people working on this will also have several stressful
| months ahead of them. From launch to full deployment so many
| things can go wrong and there is nothing that can be done when
| something fails.
| 7373737373 wrote:
| I wonder the same for large (especially international)
| companies, government bureaucracies or other organizations.
| With thousands of employees and branches in different
| locations, it must be impossible to get a full understanding of
| the state of the system.
| auto wrote:
| Same, makes you wonder how much slack/tolerance is built into
| these systems and organizations, and whether that comes in
| the form of manpower, process, etc. and whether or not it's
| planned for, or just naturally evolves in large enough
| instances.
| jasonwatkinspdx wrote:
| This is what Systems Engineers do. There's no magic bullet,
| but the basic process is lots and lots of documents. Much of
| what NASA does is published openly so you can get a feel for
| what some of these document types are like. The wiki page
| gives a decent summary.
|
| Building a model for the system is indeed a big part of the
| challenge. These days it's increasingly done as a fully
| detailed software simulation. The big CAD packages have
| specific functionality for this now. For example SpaceX runs
| on Siemens NX, and you can wade through their marketing speak
| to get some idea of how it works. CATIA is also popular with
| aerospace companies, and Autocad's products with
| architecture.
| sydthrowaway wrote:
| Ugh, I can't deal with Systems Engineering. It's a whole
| lot of gobbledygook before getting to the crux of the
| problem. A software engineering analogue would be FizzBuzz
| Enterprise Edition
|
| https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpri
| s...
| jasonwatkinspdx wrote:
| I can understand not liking how bureaucratically onerous
| it is, but we don't really have a choice. It's imperfect
| but it's the only way we've found to manage highly
| complex large scale engineering projects. You certainly
| aren't going to build something like JWT with a just YOLO
| agile process unless you're literally willing to fail
| like 50 times before you get one right (aka the USSR
| approach to rockets).
|
| The upside is automation is making it go smoother and be
| less burdensome, because simulated testing truly is high
| enough fidelity now it allows a bit more virtual trial
| and error in the process.
| bumby wrote:
| > _The upside is automation is making it go smoother and
| be less burdensome, because simulated testing truly is
| high enough fidelity_
|
| I agree to an extent, but there's also a risk of
| simulation breeding a false sense of security even when
| simulations are conducted well. The investigation of the
| CST-100 "anomalous" test flight had 21 findings related
| to software simulations and testing, some related to lack
| of fidelity. Not that fidelity wasn't possible, but it
| has some overtones of the Ariane 5 software issue in that
| there was a lack of integration testing within the
| different software components.
| spaetzleesser wrote:
| The good thing about simulations is that once you have
| figured out a problem it won't make the same mistake
| again. That's the strength of computing
| spaetzleesser wrote:
| I don't like it either but in regulated industries like
| space, medical or aerospace it seems the only way to
| manage things in a controlled way.
| spaetzleesser wrote:
| " There's no magic bullet, but the basic process is lots
| and lots of documents."
|
| That's probably it. My company has systems engineers and
| even in relatively small projects you often have
| inconsistent and incomplete requirements. It's one thing to
| design a piece of hardware but you also need to track how
| logistics and other factors have an impact on the system.
| So you need a lot of people who constantly check these
| changes.
| prpl wrote:
| Systems Engineering
| Ronson wrote:
| I seen a video on this today, (megaprojects) and I thought the
| same thing and wondered how deep it goes.
|
| Like something about the sun shield being the width of a human
| hair, someone put the idea forward, something about how many
| motors are involved in unpacking, someone put the idea forward.
| All the way to the Ariane rocket.
|
| Is for example, the Ariane rocket so good that the person in
| charge is sipping tea and eating biscuits the night before
| launch, or is that person biting their nails to the bone hoping
| that it doesn't go wrong in some way with a 10 billion payload
| on board?
| prox wrote:
| I followed their account, the last few years have been test
| after test after test.
| 0xF57A wrote:
| I was watching a presentation given by the MGT project manager at
| cal tech and he mentioned that the MGT has a lower diffraction
| limit than the JWST. I think "diffraction limit" was the term he
| used, I don't remember. The idea was that the images are supposed
| to be sharper. I was very confused about that. Why build JWST if
| MGT is going to maker cleaner images?
| bronson wrote:
| MGT is limited to the light that filters through the
| atmosphere. JWST will be tuned to longer wavelengths
| (redshifted older objects) that can only be seen in cold space.
| wolverine876 wrote:
| > JWST will be tuned to longer wavelengths (redshifted older
| objects) that can only be seen in cold space.
|
| As I understand it: We're placing it at L2 specifically for
| that reason, to isolate it from other radiation.
| jcims wrote:
| I'm just a rube but in general there are two issues:
|
| 1 - the atmosphere distorts and filters out a lot of light in
| various wavelengths. MGT likely has better resolution, but only
| for light that reaches it.
|
| 2 - JWST is primarily for infrared. Given blackbody radiation
| of the equipment itself can create a bunch of noise there, it's
| important to keep the equipment as cool as possible.
| bongoman37 wrote:
| Many wavelengths of light are simply blocked by the Earth's
| atmosphere. If you want to see them you have to go above the
| atmosphere.
| wthomp wrote:
| The diffraction limit is the fundamental resolution limit of a
| telescope. This is the size of "spot" that will be created on
| the camera sensor for a single point of light like a star [1].
|
| Its easy to calculate, just take the wavelength of the of light
| you want to observe and divide it by the diameter of the
| primary mirror (and multiply by ~1.2).
|
| For example, for JWST observing in the mid-infrared, say
| 4micron, with a 6.5 meter diameter mirror, has a resolution
| limit of: 4e-6 / 6.5 = 6.15e-7 Or about 0.6 micro-radians
| (astronomers would normally use arcseconds but leaving in
| radians for clarity).
|
| This is just the theoretical limit though, it's reduced by any
| imperfections in the optics, and for telescopes on the ground,
| it's limited by the blurring of the Earth's atmosphere to about
| 4 micro-radians.
|
| For narrow fields of view, however, ground-based telescopes can
| use adaptive optics to compensate for this shimmering/blurring
| in real time and reach close to their theoretical diffraction
| limit. Plus, they can be much bigger since we don't have to
| launch them into space. I'm not familiar with the MGT but this
| might be how it will surpass JWST in terms of resolution (which
| again also depends on the wavelength).
|
| For infrared observations though, a huge effect that can't be
| compensated for is sensitivity. At mid-infrared wavelengths,
| the Earth's atmosphere actually glows and makes it much harder
| to see faint sources. This is one of the ways JWST will really
| shine.
|
| [1] Note however that you can still do things like measure the
| position of an object to less than the diffraction limit using
| e.g. centroiding. But you can't tell if there are two objects
| or one below this limit.
| DiogenesKynikos wrote:
| I'll add to this that resolution is not the only metric by
| which you can judge a telescope. One major advantage that
| space telescopes have is that their environment is much more
| stable, making calibration (for example, of the flux of a
| source) easier. On Earth, the weather changes from night to
| night, or even from minute to minute. You're effectively
| looking through a constantly changing, semi-opaque filter -
| the atmosphere.
|
| Ground-based telescopes have their own advantages, like the
| fact that they can be much larger and therefore can collect
| much more light.
|
| This is just to say that both space- and ground-based
| telescopes are useful, and have their own strengths.
| foota wrote:
| I believe there are some kinds of photography that can only be
| done outside the atmosphere.
|
| Edit: see:
| https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope,
| particularly comparison with other telescopes. Seems the
| primary reason is for infrared photography.
| jjoonathan wrote:
| Maybe MGT isn't limited by diffraction but rather by
| atmospheric distortion (or residual distortion, because
| presumably they do what they can to correct it)? Just a guess,
| I'm not an astronomer.
| fnord77 wrote:
| what's the biggest risk? rocket failure during takeoff or
| telescope malfunction?
| xeromal wrote:
| I believe the unfurling of the solar panels is one of the
| tricky parts.
| FranOntanaya wrote:
| Most rockets these days are pretty reliable. Ariane 5 only had
| one partial failure in 20 years I believe.
| RaiausderDose wrote:
| Ariane 5 rockets have accumulated 109 launches since 1996, 104
| of which were successful, yielding a 95.4% success rate.
| Between April 2003 and December 2017, Ariane 5 flew 82
| consecutive missions without failure, but the rocket suffered a
| partial failure in January 2018
|
| from: https://en.wikipedia.org/wiki/Ariane_5
| topspin wrote:
| There are several big risks. It's impossible to rank them in a
| credible way.
|
| Obviously there are all the usual launch risks. The cryogenics
| system has had a lot of development problems. The deployment is
| staggeringly complex and involves components that are not known
| for their robustness. Finally there is no repair option; one
| critical things goes wrong or is found to be misdesigned and
| that's it.
| jamesmontalvo3 wrote:
| Nice. On track to beat https://xkcd.com/2014/
| abacadaba wrote:
| godspeed jwst team! find me an alienz!
| naikrovek wrote:
| I _really_ hope this isn 't a "MAKE IT PASS, OR ELSE" situation.
|
| this telescope doesn't deserve any functionality setbacks in
| exchange for more schedule setbacks.
|
| a telescope made late because of fixes is a fully working
| telescope. a prematurely launched telescope is broken for its
| entire service life.
| irjustin wrote:
| No, they know what's at stake. That's why it's been delayed...
| and delayed... and delayed...
|
| The question we're all biting our nails for is - Will it work?
| austincheney wrote:
| The Hubble was launched broken. The mirror had a precision
| defect and produced blurry photos. A team had to go up and
| manually correct the focus.
|
| https://www.nasa.gov/content/hubbles-mirror-flaw
| julienchastang wrote:
| A post launch fix of this type will not be possible for JWST
| due to the solar (not Earth) orbit of the instrument.
| redisman wrote:
| Can't do that with this orbit
| parksy wrote:
| I fully agree, my first gut reaction every time I read an
| update about the JWST is fear that something will go wrong. I
| hope they take all the time needed to get it right.
|
| I do also wonder if interactions with air / moisture / dust
| will degrade the components faster than they would wear out in
| space, the longer it's here on Earth? I'm guessing this is all
| accounted for too, just crazy to think of all the variables at
| play in the success of a project like this.
| 1970-01-01 wrote:
| It's pretty close to launch, but it still feels like it's not
| going to be ready for a few more years!
| baggy_trough wrote:
| Going to be amazing if this thing can actually unfurl, but I'm
| scared.
| detritus wrote:
| I don't know why, but I've had this gut-wrenching feeling for a
| couple of years now that Something Terrible is going to happen
| to this before it gets into position at L2.
|
| I really hope not, obviously, but this seems like an All Your
| Eggs In One Basket lesson in the making.
|
| We need to commodify this tech, make them somewhat disposable,
| and sent oodles of them up on Starships.
| machinehermiter wrote:
| I think this part of the problem though. We don't believe we
| can really do anything at this point so we have turned
| everything into a stochastic process with multiple draws
| needed and it gives everyone an out when things don't work.
|
| "Oops, JWST blew up, guess we just got unlucky with that
| single draw from the urn. Shouldn't have put all our eggs in
| one basket. "
|
| Just do it. No more urn thinking. Just launch , get in orbit
| and blow our minds with the data that is sent back. I don't
| want to hear about anything less than that.
| cnlevy wrote:
| Using 3 COTS (Commercial Off The Shelf) components with 90%
| reliability can ensure 99.9% redundancy instead of having a
| Unique _very reliable and even costlier_ 99.9% custom
| component can really lower costs. But it can happen only if
| mass is not a constraint.
|
| From Casey Handmer's blog:
| https://caseyhandmer.wordpress.com/2021/03/04/sls-what-now/
|
| The Perseverance Mars rover cost $2.4 billion, which works
| out to a few thousand salaries for just under a decade.
| Thousands of people are needed to build this rover because
| landing stuff on Mars is so hard that subsystem masses must
| be tracked to a tenth of a gram, on a system that weighs a
| tonne. The whole thing is meticulously handcrafted from
| custom silicon, PCBs, titanium tubes, motors, cameras, and
| other awe-inspiring instruments. Starship will be able to
| land 100 of them per flight. Now what? How can NASA feed a
| team that makes one feather light rover per decade for a
| billion dollars if the demand just jumped by a factor of a
| thousand and the unit cost fell by the same amount? Set up a
| production line? Work out how to make them with a team of
| ten? Build one every two weeks?
| throwaway2048 wrote:
| an important consideration is that SpaceX hasn't in fact,
| gotten 100 tons of equipment to mars yet.
| CamperBob2 wrote:
| They should put that team to work on next-generation tech,
| the stuff that's not yet a commodity. They can start
| working on habitat construction materials and hardware, for
| instance.
|
| Although it is interesting to consider that we've put a lot
| of expense into optimizing payloads that, in retrospect,
| would have been smarter to put into better launch vehicles.
| SpaceX probably isn't going to spend $2 billion developing
| Starship (even if Boeing would have.)
| meepmorp wrote:
| IIRC, SpaceX is getting $2.89B from NASA for the Artemis
| lander, which proposal is based on Starship. Although,
| the GAO put that on hold recently, after complaints from
| BlueOrigin and Dynetics. Hardly surprising, I guess.
| pkaye wrote:
| The material requirements are extreme to what we typically us
| on earth. Handling temperature extremes, radiation, low
| outgassing, low weight.
| detritus wrote:
| We Can Do This(tm)
|
| - ed. For clarification, I imagine that I personally can't,
| so instead:
|
| It Can Be Done(tm)
| tleilaxu wrote:
| Same feelings here!
|
| Ever since it was announced I have been anxious about it all
| going to plan.
|
| Sometimes I put myself in the shoes of the engineers and
| controllers, and I can't imagine how nerve wracking it must be,
| waiting and waiting!
|
| The thing could simply blow up on the launch pad, for goodness
| sake!
| piquadrat wrote:
| Arianespace fat-fingering an Ariane 5 into the wrong orbit
| recently didn't exactly help with my anxiety...
|
| https://spacenews.com/bad-coordinates-led-ariane-5-astray-
| la...
|
| (OTOH, I'm positive that particular issue won't reoccur)
| holler wrote:
| > The thing could simply blow up on the launch pad, for
| goodness sake!
|
| exactly, I've wondered why they don't build e.g. 2 or 3 of
| them in tandem since it'd likely be cheaper/easier to do up
| front vs after the fact if things went wrong. They would then
| have the additional telescopes if things went right, offering
| even greater access.
| jasonwatkinspdx wrote:
| See my other comment:
| https://news.ycombinator.com/item?id=27767223
|
| The timelines on this kind of project are so long spares
| don't make sense vs trying again with a new and updated
| design.
| AnimalMuppet wrote:
| With Mars landers, they _do_ build two of them. When they
| have an issue with the one on Mars, they break out the one
| here on Earth and start debugging. When they have a
| solution that works, then they know what to do with the one
| on Mars.
|
| I don't know if that would work on telescopes, though - I
| suspect that the copy wouldn't have the full optics
| installed.
| OrvalWintermute wrote:
| You're correct - building constellations is definitely much
| cheaper.
|
| For an observational/capability platform such as for DoD or
| NOAA, making a large number in a series makes sense. For a
| research platform (NASA/NSF) that same idea doesn't apply,
| since science objectives dominate the discussion.
| lisper wrote:
| I used to work at JPL, and I was there when the sky-crane (the
| system currently used to land rovers on Mars) was first
| proposed back in the late 90s. I remember thinking to myself,
| "That is the craziest idea I have ever heard, there is no way
| that could possibly work." But it did.
|
| Never bet against NASA engineers. Sure, they have the odd high-
| profile screwup, but on the whole they are shockingly
| competent.
| jcims wrote:
| Do you know if there is any test footage of that anywhere?
| That's, to me anyway, the second most amazing thing about the
| sky crane...that I can't find a single frame of it in
| operation on earth.
| hypertele-Xii wrote:
| Earth physics are different from Mars physics. What works
| there wouldn't work here; can't just try it out and see if
| it works.
| jcims wrote:
| Sure the final mission configuration isn't exactly what
| they would test, but the differences in the sky crane
| maneuver on Mars and Earth would be relatively easy to
| factor in (ok, that might be an exaggeration, but its
| doable). There is a ton of control development that would
| need to be sorted out so they knew how to integrate it
| all. For example, I had heard that the primary indicator
| that the rover had touched down simply watching the
| throttle on the closed loop flight control system. When
| it throttled down it meant the rockets were no longer
| suspending the weight of the rover. If true, I would
| think you would want to test that quite a bit...
|
| FWIW they tested missile defense 'kill vehicles' on the
| ground and they will operate at or near orbital velocity
| in space. The main 'hover thruster' would likely be
| completely unnecessary in a live exercise:
|
| https://www.youtube.com/watch?v=KBMU6l6GsdM
| scrumbledober wrote:
| would it have had enough thrust to work in earth gravity?
| lisper wrote:
| Sorry I have no idea.
| dirtyid wrote:
| Just want launch to be over so I don't have to deal with JW
| news anxiety anymore.
| bpodgursky wrote:
| I almost want the unfurling to get stuck, just b/c SpaceX
| launching a manned Starship out to a LaGrange point to hotfix
| it would be super cool.
| bronson wrote:
| Fly out there, spacewalk over, give it a little jiggle, looks
| good, fly home.
|
| It would be like driving six hours to push a power button,
| but epic.
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