It is literally a black hole...
Paris, because, well...
That's that then. The Arecibo Observatory appears to have been destroyed with the collapse of the platform previously suspended above the giant dish. Before and after shots of the facility show the triangular platform, which had hung over the dish, is no longer in place. Ayer fue la última vez que visite esta belleza de lugar …
https://www.nature.com/articles/d41586-020-03270-9
"NSF officials insist that the cable failures came as a surprise. After the first, engineering teams spotted a handful of broken wires on the second cable, which was more crucial to holding up the platform, but they did not see it as a major problem because the weight it was carrying was well within its design capacity. “It was not seen as an immediate threat,” says Ashley Zauderer, programme director for Arecibo at the NSF.
But that main cable, which was installed in the early 1960s, had apparently degraded over time. Over the years, external review committees have highlighted the ongoing need to maintain the ageing cables. Zauderer said that maintenance in recent years had been completed according to schedule."
Just like suspension bridges that will fail eventually. Anything that is cable-stayed suffers from this when the supporting cables are under tension. Bridges are designed such that over it's life x number of strands within the cable will break. Once that limit it reach load has to be reduced. That is what has happened to the old Severn Bridge. I believe they do something funky with strain gauges and listening for "pings" as individual strands break. Count the "pings" and in theory you know how many are left and can work out when it falls down. Quite what you do if you lose count I don't know.
The way the cables are spun in-situ means that you cannot replace them without taking the entire deck off. At that point it is cheaper to just build a new one.
It's the Forth Road Bridge which goes <plink> every so often. The suspension cable were, as you say, woven in situ with around 10,000 strands of piano wire each side and are unrepairable. Its replacement, the Queensferry Crossing, has been designed so that any of its cable stays can be replaced without even closing the bridge.
According to this story from 2013, the Mackinac Bridge (the longest suspension bridge when it was opened, and still the longest between anchorages in the Western Hemisphere) has its cables inspected visually. They open sections of the sheathing and use wedges to separate strands.
In that story, the Mackinac Bridge Authority claims the bridge's lifespan is "unlimited", which suggests they have a plan for repairing the cables, should that become necessary. (I'm not sure what their plan is for when the sun gets hot enough to melt the thing.) But at the claimed rate of 0.3% corrosion after 56 years, they may just be assuming it will be Someone Else's Problem when it finally becomes significant.
The mighty Mac, funny you mention it directly after someone mentions the Forth bridge, born in Scotland, spent most of my life here, yet I've been across the Mac more times than the Forth..but then it's understandable really, me being a west coaster and the Forth bridge being an east coast thingie..
Re: "NSF officials insist that the cable failures came as a surprise. After the first, engineering teams spotted a handful of broken wires on the second cable, which was more crucial to holding up the platform, but they did not see it as a major problem because the weight it was carrying was well within its design capacity"
Where I work, we have special hooks either side of each window that are apparently there so that anyone working on the window outside can attach a safety harness to. Admittedly, I've never seen one being used, but I am rarely there when they are doing any work on the windows. These hooks are tested annually.
Similarly, the lifts, because they are ten years old and while reliable, are apparently due for major refurbishment or even replacement, are taken out of service once a year and things like the cable tested.
While these are items that support humans (who are more important than mere hardware), those humans only weigh a few tens of kilos each. Even a fully laden lift is likely to be around 1 ton (admittedly, that is a guess), but the load bearing capabilities of those items is assessed regularly.
Cables and other hardware ages. Just because it was designed to carry a certain amount of weight doesn't mean it is able to 60 years later.. The US should have been testing that cable regularly, and if any failed the test, it should have been replaced when detected.
That said, I have no idea how you would replace a cable supporting a 900 ton object safely, although i suspect had the other cables been up to spec, they probably could have disconnected any cable that needed replacing and rely on the other cables to support the weight while the faulty one was replaced.
That said, I have no idea how you would replace a cable supporting a 900 ton object safely, although i suspect had the other cables been up to spec, they probably could have disconnected any cable that needed replacing and rely on the other cables to support the weight while the faulty one was replaced.
I expect that's how you would plan for future maintenance. If, say, a system needed three cables of a particular spec, you'd have at least five (allowing for an unknown near-fail status in any of the remaining four) meaning you always have at least the three you need in place when replacing one.
But maintainability doesn't give YOU the politician any usable credit, nor does it help your cronies 20, 30 or 40 years down the road.
After 60 years of service it sounds like cumulative metal fatigue. Not a lot to be done to prevent it, but it might have been possible to monitor it and replace fatigued cables before they failed. I guess the problem is that limited budgets get preferentially allocated to new projects and older ones just go on being used on the basis that they're still working.
Fortunately this is only an old (almost) obsolete telescope not a bridge, highway or dam or other vital infrastructure
"Yes, obsolete and since superseded by all of the other radio telescopes that have been built that can easily match and better its performance."
You might want to tell the scientists that ...
https://www.nature.com/articles/d41586-020-03270-9
"Much of the work conducted at Arecibo, however, could be done only with its unique array of astronomical instrumentation. “The Arecibo Telescope is irreplaceable,” said a statement from two major US radio-astronomy organizations, the National Radio Astronomy Observatory in Charlottesville, Virginia, and the Green Bank Observatory in West Virginia."
I don't think it "clearly was a joke". I withheld judgement on the assumption that the post might have been sarcastic, but it was definitely in Poe's Law territory.
People posting sarcasm online need either thick skins, or the understanding that not all their interlocutors share their knowledge and assumptions.
I am unfamiliar with Poe's Law but will state that I do indeed have a thick skin otherwise I could just have withdrawn it. As it it I accept it wasn't interpreted as such, especially with a broad range of readers found on here, and will take the lesson and learn.
I'd rather just explain myself so at least some readers will then understand my intentions (although I'm still baffled that the 'dozens of alternatives' snippet was picked up on more) .
[Edit: it looks like the comment I'm replying to was a joke which I should have realised in retrospect. I'll leave the below just in case someone else doesn't realised.]
There is nothing which can do what Arecibo could do. FAST (in China) may be able to do it in due course, but it certainly can not now.
Well, it's certainly wasn't obsolete, nor even close.
But it is a very visual illustration of the parlous state of US infrastructure and rather vindicates what the ASCE have been banging on about.
Not that we should need such an illustration, but many will have forgotten about the last Green Bank Telescope.
It was (I think) the only large telescope capable of doing x-ray imaging of near earth objects... Basically it was vital for spotting, and figuring out the trajectory/distance/size of potential asteroids that could impact earth.
The one they recently built in China... isn't capable of that.
There is a big bias towards "investing in the future" as opposed to running existing hardware. It starts from the top, e.g., the German government will take debt to "invest" but not to fund running costs. And the distinction trickles down into individual research budgets that contain big investment positions but miniscule funding for running cost. It is often easier to purchase a new device (for much higher cost) than to repair the functionally equivalent old one. The latter is then discarded as broken, even though you might just replace the worn-out gaskets.
So think twice, next time, before you vote for that politician who promises grandiose "investments into science". Science needs funding, not investment.
e.g., the German government will take debt to "invest" but not to fund running costs.
That's entirely as it should be. Borrowing to build a hospital is fine (it'll pay back over 50years in reduced time off sick, improved health outcomes for the population, etc). Borrowing to pay your nurses is unsustainable. You borrow your payroll for this year and then what... next year you still have a hospital, but you're going to take debt again for another year's worth of payroll?
A bank will lend a company money to build a new factory or tool up a line for their new product but they won't just give you a loan to cover your payroll for a year - because if you can't afford payroll this year, then how will you afford it next year (obviously there are some corner cases - special projects, R&D funding where you might be able to take debt - but not in day-to-day trading).
If research budgets are being oriented to investment rather than maintenance then that's on the shoulders of the governing committee. If maintenance is swallowing up their entire annual budget then either they have too much stuff and need to cast off the lowest ROI projects, or the budget isn't big enough - I suspect we know what's the case in the US.
It's also notable that the US House of representatives passed legislation in 2015 requiring the National Science Foundation to get permission for certain types of spending, reducing autonomy over how their budget is used and introducing political interests - rarely a good thing.
All that being said, it's not inconceivable that the upfront investment should include an endowment to cover some/all of the maintenance costs, available as a restricted fund for the lifetime of the project. But you can't just take debt on an annual, ongoing basis to cover your running & maintenance costs - if you have to do that, you probably can't afford the project to start with.
That's often the way of large research projects these days - apply for funding to build the instrument, get funding yay! Who runs it/maintenance? Hmm we'll think about that later, i.e. we hope some kind soul will foot the bill since shame to let this expensive instrument go to waste.
LIfe time costing is poorly understood and deliberately talked down when the initial research project is proposed. For example it is not uncommon for the lifetime support costs of a large engineering or complex computer project to be 95% of the overall cost So the immediate upfront cost which is what everyone crows about is only 5% of the overall costs. Making a 'saving' of 10% in the immediate up front cost is in actuality only 0,5% of the overall costs and may increase the lifetime costs well beyond that 0.5% saving. It is VERY difficult to persuade people to talk of Lifetime costs for this reason as a 20 year project can have very alarming total costs.
The cost of HS2 maintenance will be 25% of the original price per year.
Source?
Annual Maintenance & Renewals costs of HS2 will not be £16-25Bn.
Unless you mean 25% of the annual construction costs (a weird metric to use), which are £8-10Bn/yr over the construction period, so £2-3Bn/yr. In which case... still no. HS1 has an OMRC <£100m/yr. There is no reason to think that HS2's OMRC will be out of proportion with HS1 (larger obviously, more stations and longer line, but not disproportionately so).
The facility was originally built largely (maybe completely?) using funding from the Department of Defense. So like the overall missile defense program from the 60s that the dish was originally affiliated with, that source of funding may have dried up as the DoD's priorities changed.
I don't blame the DoD really, because the military budget has gone from probably 8% or 10% of U.S. GDP in the early 60s to about 3.7% of GDP now.
The Iron Bridge, 1781, still going strong, although it doesn't carry traffic now https://en.wikipedia.org/wiki/The_Iron_Bridge. I see the beautiful Galton Bridge, 1829, every day when I catch the train to work https://en.wikipedia.org/wiki/Galton_Bridge
Yep - they knew how to build stuff then, unlike today. A five year old building of classrooms where I work, has a leaky roof, and when a truck goes by on the road, the internal walls shake so badly, the teachers can't write on their interactive whiteboards.
Bit of a selection bias there! The old stuff that collapsed 5 yrs after building has long since been built over and forgotten. There is also some case that structural reliability was not well understood so buildings were over engineered, e.g those gothic cathedrals which supposedly could lose a great deal of the stone if redesigned with modern methods.
The Arecibo affair reminds me of the Forth Bridge (Scotland! in case there are any others...) where only relatively recently did they discover severe corrosion problems in the support cables. Of course there the money had to be found to put up a new bridge as it is a major transport route.
For a science facility it's only a pity a some philanthropic tech mogul couldn't have been tapped for the money (Bezos? Gates? Musk? Branson?).
Hammersmith Bridge in London is currently in critical danger of collapse (it was back in the news a few days ago, as it was declared too dangerous to run the Boat Race under it). Vauxhall Bridge and Lambeth Bridge are also badly damaged. A row is currently ongoing about who is going to pay to fix them, and what happened to the maintenance budgets for them to get in such a bad state. I believe the current mayor is pointing out that they had been neglected for many many years. A certain former mayor has not yet commented, as far as I know.
That it happened all by itself and not when someone was laying charges to bring it down n a controlled way. Judging from the pictures, the three towers remain sans cables, so the whiplash when the 900 ton platform dropped and the cables snapped would have been lethal to anyone in the way.
It did some great observing, but now it should be safe enough to salvage the remains of the dish for science museums around the world.
Sad though, as it is the end of an era.
That it happened all by itself
A small earthquake probably gave it the shove it needed to pop the next cable.
Scott Munley re-enacted it in MS Paint.
There was a Gofundme for stray cats at Arecibo; maybe we should have started one for maintenance, too.
"Much better to turn it into a massive skate/bike park. A half-dome instead of a half-pipe, you see."
The inverted "dome" is pretty much destroyed...the August "storm" casued a cable to break and that fell to one side of the main buildings...and now the receiver section has come down, it decided to land almost opposite the first "hole" in the dish.
Likewise the main boom, under which the receiver section was "hung", fell down onto another part of the dome.
And needless to say the dome was never built to withstand high tonnage of parts falling down from a great height, onto the panels... :-(
Probably a good thing uk.gov isn't in charge of that or we'd have a "telescope company that doesn't have any telescopes" story. Or possibly an "ex-next door neighbour of cabinet minister, who owns a sandwich shop owner and isn't really part of the science game but reckoned the toasting oven could probably be repurposed to produce deep space telemetry components" one.
I suppose all engineering things come to the end of their life but I can't help wondering what regular maintenance had been done (if at all) and if the outcome would have been different if a bit more money had been spent on cable inspections and the like. Stuff like that, exposed to the elements, is bound to corrode with (as has been seen) disastrous results. Great pity that the unique icon had to end its days in such an ignominious fashion.
...abd don't forget it's not "normal" atmospherics causing the corrosion...Puerto Rico is very "tropical" and being an island, there's a lot of salt in the air, as Arecibo is just 18 deg North of the equator...
And even well made 60 year old support cables will not last forever.
The pity is that a lack of funding failed to be invested in the maintenance of the facility over time and eventaully something was bound to happen.
Fortunately the issues in August and November was just enough to cause some safety fears to eb rasied and this ensured that no-one was working on the site...as without those storms, it is quite possible it may have collapsed on it's own anyway. :-(
The Hulse-Taylor pulsar was discovered in 1974 using Arecibo, and many – perhaps most – of the observations of it were done there. Hulse-Taylor is extremely significant, to put it rather mildly. After discovering it, Hulse & Taylor realised, based on periodic shifts in the frequency, that it was a binary system with two neutron stars in orbit around each other, of which we were 'hearing' one. And then by making observations over long periods they discovered that the period of the orbit was decreasing: the system was losing energy. Well, General Relativity predicts that such a system should emit significant amounts of power through gravitational waves, and the predictions of GR agree extremely accurately with the observations.
Hulse-Taylor thus provided a very important experimental test of GR and was the first (indirect) detection of gravitational waves. Whether LIGO would have been built without the evidence it provided I don't know, but I wouldn't be surprised if it wouldn't have been. Hulse & Taylor won a Nobel prize for this.
And that's far from all it did. The critical observations of the pulsar at the centre of the Crab Nebula, and hence the discovery of neutron stars, were done there in 1968.
This place was so important.
Around 2001 NASA had already withdrawn funding for Arecibo, and the observatory got pushed off onto NSF, which had so much interest in running the site that by 2014 they were looking to decommission the place despite NASA pouring in a few million of funding a year again around 2012. Only a group led by the University of Florida putting in money saved it.
The time to save Arecibo was probably around 2001. From there it has been a slow slog into corrosion and wear on the supporting cables and other structures. As engineers who examined the structure earlier this year noted, the cables had degraded to a point where they could not take more than half of their originally rated load.
Arecibo hadn't seen a maintenance budget and only a minimal operating budget for the last two decades. There is no large infrastructure project that can survive that long without maintenance and not suffer some kind of catastrophic failure. Just ask the US what happened to the last few bridges where they skimped on maintenance.
Of all the places out there to "Look at space" Chile's desert is considered one of the best ones.
https://www.astronomictourism.com/astronomical-observatories-chile.html
A bit of a shame what happened to this one but is not like "The weather conditions are going to get more extreme" has not been a know thing since the seventies.
Granted back then people believed the World was going to get... COLDER, not warmer.
Arecibo has the benefit of being in the norther hemisphere, so it can look at parts of the sky that will not be available to a telescope in Chile.
(We all know that the aliens are responsible for this. Now we won't be able to see their attack fleet coming!)
You can't see the whole sky from any one place on Earth. You can't simply replace Northern Hemisphere facilities with a new Chilean observatory if it can't see the bits of sky that it needs to.
But also, Chile doesn't have the karst landscape that Puerto Rico and the Guizhou region of China were selected for. Sure, you could dig a big hole in the Chilean desert (for a price), but why not go where nature has done the work for you?
Replacing it with an array of smaller dishes is also impractical thanks to the nature of r2. To match the collecting area (~70,685m2) and gain the sensitivity of Arecibo's 300m dish, you'd need ~10 Green-Bank-class 100m dishes. It added huge sensitivity to any array it cooperated with. Adding Arecibo to a Very Long Baseline Array observing campaign improved the sensitivity by a factor of five.
As it stands, there are only two such telescopes anywhere in the world (Green Bank & Effelsburg, Germany). People rarely venture above 12-15m for steerable telescopes, which somewhat of a sweet spot for cost and maintenance using fairly off-the-shelf engineering.
Even the Very Large Array - with it's 27 dishes (each 25m diameter) - "only" manages 13,250m2.
It was not obsolete: not anywhere near. There is no other system which can do what Arecibo was still doing, at least in part because it was a radar, not just a telescope. The SKA is not a radar, is not in the northern hemisphere (which kind of matters if you want to look at things visible from the northern hemisphere), and due to the loss of Arecibo will be even more oversubscribed. Arecibo is not irreplaceable, but there is no current replacement for it: research that Arecibo enabled can not now be done.
So, perhaps you should listen to what actual radio astronomy people say before making a fool of yourself (I am not one, but I do know how to listen to them)?
Also, don't you think you should avoid casual bigotry? Especially as it turns out that Japan is really rather good at engineering.
The world has lost an iconic scientific instrument. Yes it was built by the USA, funded by NASA, NSF, UoF, but it was used by scientists from across the globe and broadened our horizons considerably. Chances are it will not be replaced with anything similar as arrays are cheaper, more efficient, and more versatile, but it still deserves respect. My sympathies are with the people who work and worked there, and their families, and I'm glad nobody was hurt.
That's been "photoshopped". If you look carefully the cables have completely vanished, and the towers in the "after" shot have fewer tiers than in the "before" one.
Genuine photo at https://astronomy.stackexchange.com/q/38585/7982
Which just goes to show that one shouldn't take stuff on Twitter at face value.
Not to pick on you since you did say "why would someone fake an image", but It's sad that people's first thought is "it's a fake!!!" rather than "I wonder why the debri isn't visible".
Unfortunately that seems to be the trend these days. Everyone commenting thinks they know better and if they don't understand something it's either a fake or the fault of the other party. Never because the commenter doesn't have the full picture, oh no.
From the way the debris are spread all over the place you can imagine the chain of event.
The cantilevered structure is spread over the face on the side of the antenna so the cables between the two top pillars probably held while the structure was going down.
Zooming on the picture you can see that all the towers lost some bit.
The top left missing bit is almost at the bottom of the tower along with a tangle of cables that can be followed to the antenna.
the top right one doesn't seem to be missing much, but the cables seems to have damaged a building behind the tower when they were ripped from it's top.
The bottom tower seems to be the most damaged one, with fallen bits apparently behind it.
At a guess ( and according to the way the debris are spread ) that's on this one that the cables snapped.
It is tempting to assume a cable failure, but if the top of the lower tower in the photograph failed, that could produce a similar catastrophic event. I wonder where the top of the bottom tower is? Each of the towers seems to have lost its top section.
Picture of damage to the dish before the final collapse at:
https://www.bbc.co.uk/news/science-environment-55008567
Consider there was ~900 tons spread out over the three towers. When the final cable snapped (taking the rest on that leg with it almost instantly), the central mass went into near free-fall (there seems to have been a bit of swing induced by the remaining legs). EACH of the towers was suddenly unloaded for the first time in 60ish years, starting with the one where the cable snapped, and ending with the other two when the central mass hit the deck. The rebound from being unloaded popped the tops off the towers. I'll leave it as an exercise for the reader to work out the vectors describing where everything landed.
Thanks for the more recent photos which I think just about wrap this up. I'd comment that Google Maps shows a cluster of (maintenance?) buildings in the area from which that the original Twitter photo was almost certainly taken, so presumably somebody got out quickly to take a photo or there might have been a camera set up taking timelapse shots.
Finally, I think we could all do with remembering the island and people of Puerto Rico, which is much more than just a convenient foundation for the USA's astronomical facilities.
Those cables definitely look their age
And you can see the tops of the towers snapping off.
"I have no doubt that in reality, the future will be vastly more surprising than anything I can imagine.
Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we CAN suppose."
— John Burdon Sanderson Haldane, FRS (1892—1964)
("Possible Worlds and Other Papers," 1927, p. 286)
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“Once in a cycle, the comet doubles its lonesome track.
Enriched with the tears of a thousand years, Aeschylus wanders back.”
— John G. Neihardt (1881–1973)
("A Cycle of the West," 1949)
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(As quoted by Loren Eiseley for the epigraph to his "The Invisible Pyramid," 1969)