Arecibo Collapsed Because of Engineering Failures That Inspectors Failed To Spot (behindtheblack.com) 78
An anonymous reader quotes a report from Behind the Black: According to a new very detailed engineering analysis into the causes of the collapse of the Arecibo radio telescope in Puerto Rico in 2020, the failure was caused first by a surprising interaction between the radio electronics of Arecibo and the traditional methods used to anchor the cables, and second by a failure of inspections to spot the problem as it became obvious.
The surprising engineering discovery is illustrated [here (PNG)]. The main antenna of Arecibo was suspended above the bowl below by three main cables. The figure shows the basic design of the system used to anchor the cable ends to their sockets. The end of the cable bunches would be inserted into the socket, spread apart, and then zinc would be poured in to fill the gap and then act as a plug and glue to hold the cables in place. According to the report, this system has been used for decades in many applications very successfully.
What the report found however was at Arecibo over time the cable bunch and zinc plug slowly began to pull out of the socket, what the report labels as "zinc creep." This was noted by inspectors, but dismissed as a concern because they still believed the engineering margins were still high enough to prevent failure at this point. In fact, this is exactly where the structure failed in 2020, with the first cable separating as shown in August 2020. The second cable did so in a similar manner in November 2020.
The report concluded that the "only hypothesis the committee could develop that provides a plausible but unprovable answer to all these questions and the observed socket failure pattern is that the socket zinc creep was unexpectedly accelerated in the Arecibo Telescope's uniquely powerful electromagnetic radiation environment. The Arecibo Telescope cables were suspended across the beam of 'the most powerful radio transmitter on Earth.'"
The surprising engineering discovery is illustrated [here (PNG)]. The main antenna of Arecibo was suspended above the bowl below by three main cables. The figure shows the basic design of the system used to anchor the cable ends to their sockets. The end of the cable bunches would be inserted into the socket, spread apart, and then zinc would be poured in to fill the gap and then act as a plug and glue to hold the cables in place. According to the report, this system has been used for decades in many applications very successfully.
What the report found however was at Arecibo over time the cable bunch and zinc plug slowly began to pull out of the socket, what the report labels as "zinc creep." This was noted by inspectors, but dismissed as a concern because they still believed the engineering margins were still high enough to prevent failure at this point. In fact, this is exactly where the structure failed in 2020, with the first cable separating as shown in August 2020. The second cable did so in a similar manner in November 2020.
The report concluded that the "only hypothesis the committee could develop that provides a plausible but unprovable answer to all these questions and the observed socket failure pattern is that the socket zinc creep was unexpectedly accelerated in the Arecibo Telescope's uniquely powerful electromagnetic radiation environment. The Arecibo Telescope cables were suspended across the beam of 'the most powerful radio transmitter on Earth.'"
Re:Since the problem has been identified (Score:5, Insightful)
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Geez, really got off track about the causes of the collapse of the Arecibo radio telescope which happened long before Ukraine got invaded by Russia
The summary says Arecibo collapsed in 2020, while the Russian invasion of Ukraine started in 2014 with the annexation of Crimea. It's true that Western nations only started to worry about it in 2022 when the invasion expanded into an all-out war in multiple fronts. I guess if we'd taken action earlier, we wouldn't be in this mess.
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... If we can send Ukraine $100B/year and cut half of our other defense spending, that's... ...
...we send Ukraine money on top of our existing defense budget and
I hate adding more to an off-topic conversation, but you are perpetuating an inaccuracy here. The federal budgeting for Ukraine is not, for the most part, "sent to Ukraine." Mostly what it's doing is paying US manufacturers to make munitions, which are sent to Ukraine. https://www.csis.org/analysis/... [csis.org]
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Indeed. Russia has gone from having the second best military in the world to the second best military in Ukraine, and now the third best military in Russia. Or possibly the fourth best now that North Korea is there.
Re: Since the problem has been identified (Score:1)
What do you mean a PP tries to minimise expense. A PP tries to maximise what it charges its customer (us).
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What do you mean a PP tries to minimise expense. A PP tries to maximise what it charges its customer (us).
I think that was more about individuals rather than corporations. That said, corporations try to minimize their expenses, too, because expenses cut into how much they make from what they charge their customers.
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Okay, let's let facts intrude on things.
In the first two years, there was a total of approximately $380B of global aid [cnn.com] "committed" to Ukraine, although "commitments" are often vastly more ambitious than actual reality [ifw-kiel.de]. In the ballpark of $190B/yr. Europe provides the majority of this. However, this is a mixture of military aid, humanitarian assistance, financial support, and a variety of other factors (more on this in a bit). Historically the US was the main military contributor, with the EU more focuse [atradius.com]
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Oh, and forgot to add, re, economics: Russia's inflation is so out of control that the central bank has set its interest rate to 21% to try to slow it [cnbc.com] (US fed rate: 5%). Russia's short-term bond yields are now similar to Uganda's [tradingeconomics.com], and continuously worsening. Meanwhile, in the intense labour shortage, reduced maintenance has been slowly hollowing out an already often fragile infrastructure system.
Basically, the country is funding its war by mortgaging its past (Soviet equipment inheritance), its present, an
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US military commitments (2/3rds of total US commitments) are now only about 2/5ths of the military total, the EU another 2/5ths... as of 2 years in, EU totals were... $30B military aid.
DOD disagrees with you [defense.gov].
From the start of the invasion to about two weeks ago, US military aid to Ukraine was $59.1B.
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Why did you link a report from Q4 in a comparison to numbers from mid-Q1?
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I didn't see a date in your post. But, fair enough. Here's as of April [defense.gov], just after the end of 1Q, at $50.9B.
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"Probably less than 1% of what we have given to Ukraine thus far this year."
This is a quote from the paper? Why on Earth would you do this? Whatever your politics, referencing a politically polarized subject in your paper about radio astronomy all but ensures that the subsequent discussion is going to be about the political thing, not the radio astronomy. Just look at the first twenty comments on this Slashdot article! Even if you were attempting to exploit the emotionality of politics to make your dry
Re:Since the problem has been identified (Score:4, Informative)
No they don't.
The legislators themselves get some too.
No they don't.
Contractors make some money.
Of course contractors are making money. They're the ones being paid to make the munitions and equipment. Did you think the government was making this stuff?
Some of the money actually goes to the over-priced weapon systems and shipping them.
If you think they're overpriced the U.S. governmet would love to see you bid on their weapons contracts.
This isn't Russia where corruption is the name of the game [newsweek.com].
if we want the government to spend our money on useful endeavors, rather than destroying things and people, we need to somehow replace Ukraine with scientific projects
We can't defend democracy AND work on scientific projects at the same time? Many scientific endeavors come from work in the military. Frequency hopping, GPS, and radar to name just three off the top of my head.
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This isn't Russia where corruption is the name of the game.
*blink* *blink*
Really? The corruption in the US is merely better managed, but it is just as rotten as Russia. The quality is all that differs.
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Exactly what use do you think a howitzer is going to do for Arecibo?
Re: Since the problem has been identified (Score:1)
I dunno, could be used to fire a projectile with new cables in tow?
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To be honest, when it was clear that Arecibo was in dire straits and they had given up on trying to save it due to excessive risk to personnel, I was kinda thinking that it might be worth a Hail Mary of trying to blast hardware off it, up to and including severing the entire azimuth arm at its connection points, to lighten the load enough that you'd have the time and safety for longer-term, less destructive approaches. Though you'd destroy a lot of expensive hardware (and the middle of the dish)), at least
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Ukraine funding is small minor compared to what we give Israel.
Re: FTW, Puerto Rico. (Score:1)
Rado telescope is an RF transmitter? I learned something today.
Re: FTW, Puerto Rico. (Score:5, Informative)
Re: FTW, Puerto Rico. (Score:4, Informative)
Source: https://en.wikipedia.org/wiki/... [wikipedia.org]
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"...the most powerful radio transmitter on Earth"? (Score:2)
How? How do these radio waves affect the zinc filler in the socket? What happens?
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It probably heats up the zinc? Maybe?
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Re: "...the most powerful radio transmitter on Ear (Score:2)
The two mechanisms I can think of would be that either it heats it up, or it causes things to vibrate and slowly work loose. It would only have to be a tiny effect, it happened over decades after all.
Re:"...the most powerful radio transmitter on Eart (Score:5, Informative)
Long-term, low-current electroplasticity. The radio waves induced a current in the cables, which ended up grounding through some of the sockets. Or something like that. The report says:
The only hypothesis the committee developed that could possibly explain the measured patterns and ultimate effects of the observed socket zinc creep acceleration was the effect of electroplasticity (EP). EP is "the reduction in flow stress of a material undergoing deformation on passing an electrical pulse through it." EP was first discovered by Eugene S. Machlin, who reported in 1959 that making a 6 kV (dc) closed circuit with NaCl crystals made them weaker and more ductile. Later, in 1963, Troitskii and Likhtman reported the same EP effect in zinc crystals. In 2020, Baumgardner et al. reported the following:
A low-energy electroplastic effect in aluminum alloys at an ultra-low current density threshold between 0.035 and 0.1 A/mm2 that resulted in EP-assisted reduction in hardness of 10% and increases in creep rate up to 38% over a range in temperatures from 25C to 100C. Systematic experiments and ab initio calculations showed that Mg-Zn alloying elements in Al7050 were the origin of the EP effect.
"To date, the theories of Joule-heating, electron-wind force, and de-pinning from paramagnetic obstacles are the most commonly invoked explanations for instances of EP observed in different materials."
You can get the whole report ftom here [nationalacademies.org]
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They attract aliens, which beam down and steal the zinc for their saucers' corrosion protection systems.
Well - obviously! (Score:2)
What other explanation could possibly be true... ;)
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How? How do these radio waves affect the zinc filler in the socket? What happens?
The radio waves would have induced electrical currents in the entire structure. And any mechanical metal-to-metal junctions would have been subject to ingress of water and contaminants. I'm just guessing here, but I suspect that at these points the current flow would be destructive in the same way that an electroplating process sometimes sacrifices one of the electrodes used.
Note that such junctions can become de-facto batteries in any structure where different metals com into contact. The resulting current
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>During the short term these effects might have been negligible, but over decades the effect could have been pretty pronounced. It may also be one of those "the worse it gets, the faster it gets worse" scenarios.
A pity they didn't pick it up soon enough to devise a sacrificial ground cabling system.
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Zinc is a bizarre choice for an anchor material. Zinc is used on structures as a sacrificial part that attracts galvanic corrosion away from other components. In other words, the zinc corrodes instead of the other metal stuff.
Electricity can speed up galvanic corrosion. That's how batteries work.
To use it as a key structural part in a salty environment with electricity flowing through it seems really obviously like a bad idea.
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How? How do these radio waves affect the zinc filler in the socket? What happens?
Well, that is of course the big question and reading the report I was left unconvinced on this matter. The "It was the radio waves what did it" mechanism is only really proposed on the basis that the committee couldn't think of anything else, but I have serious doubts about their ability to assess this as some of their arguments seemed rather suspect.
I'm a professional antenna engineer and I was dismayed by their extensive discussion about whether or not the cables might have had an earth connection whic
Plenty of blame to go around (Score:1)
I'm sure having (ex) OO agents running around conducting firefights on the array back in the 90s didn't help matters either, along with converting it into an easily drained and refilled lake to avoid aerial detection.
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Safest way to cut the funding (Score:2)
For a long time there was talk of closing down Arecibo, so letting it collapse is the safest way to stop funding it.
Closing it down would involve saving the most expensive parts, the detectors in the hub suspended above the reflector.
This will also result in the expensive parts being stored for use in a future radio telescope.
The collapse and their destruction solved that problem too.
Trying to follow this (Score:5, Funny)
Classism creates corruption which leads directly to incompetence. So long as the upper classes are in control and driven by greed, corruption and incompetence will continue to get worse until society collapses once again.
So society is the dish, greed is the zinc and the RF is the upper classes? Or is corruption the inspectors? And where do the aliens (each according to their needs) fit into this? Sorry, I am lost...
Remember this was in Puerto Rico..... (Score:1)
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A World Without Zinc (Score:4, Funny)
Come back zinc!! Come baaaaack!!!
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That's a copper out
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Data point (Score:5, Informative)
Those poured-zinc-in-socket joints are called "Spelter Sockets", and they are ludicrously strong.
Here's a video that shows a Spelter socket being poured.
https://www.youtube.com/watch?... [youtube.com]
This technology has been in use for a very long time, so there had to be something very odd in this application for it to have failed unexpectedly.
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Cool video.
Aren't these used all the time on cable-stayed radio transmission towers out West?
Was Arecibo still in operation after the first cable failed?
If so did they not see where the first cable failed and then inspect that point at other cables?
If the socket was majorly deformed on the first cable did the inspector not know what to look for?
Their theory on zinc migration is interesting but that shouldn't have any impact on rigging inspection, except as an academic footnote.
This seems like something insu
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Insufficient data to answer. My exposure to spelter sockets is from a brief hyperfixation (unsuccessfully) trying to find a cheap 3d printable mechanism for strongly attaching braided monofilament to plastic components in such a way that the line would not saw through the plastic.
Transmitter? (Score:2)
It's a telescope, so it's a receiver. Why - and, indeed, what - was it transmitting?
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It was used to map the extra-terrestrial bodies with RADAR, including
Venus, https://iopscience.iop.org/art... [iop.org]
Mars, https://www.sciencedirect.com/... [sciencedirect.com]
Titan, https://www.researchgate.net/f... [researchgate.net]
the Moon https://www.sciencedirect.com/... [sciencedirect.com]
and I'm sure there are many, many more reports. In my only partially informed opinion, it was valuable enough that it should be rebuilt.
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So this begs the question: if they limit it to only receiving, would it last longer?
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It could send out radar pulses to objects within the solar system, then listen to the echo. This could be for basic ranging and getting precise orbital parameters, it also could be used for imaging otherwise dim objects, like asteroids [nasa.gov]. This is how, for instance, we could confirm that asteroid Didymos had a moon [planetary.org], which made it a perfect candidate for smashing an impactor into [wikipedia.org].
When you think about it, this is pretty wi
Best just build a new facility (Score:2)
They GLUED the cables in? (Score:2)
Re: They GLUED the cables in? (Score:1)
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LOL, you saw "glue" in TFA and read no further.
They used molten zinc to "plug" and "glue" the cables. Is that "welding or something" enough for you?
They didn't just buy a vat of Gorilla adhesive from Home Depot and pour it in.
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Inspectors inspect (Score:3, Insightful)
Creep was inspected, noted and documented
Inspectors have neither the technical background to adjudge the degree of safety margin engineered into the fastener system nor physics that would explain it in the first instance.
Inspected, noted, documented Arecibo management, policy and procedures failed science. Its a simple process if ignored invalidates all means to capturing a problem before it cascades into collapse.
That no one lost a job over the loss of structure and telescope tells that leadership was too big to fail on the management team. Public-facing unsubstantiated conjecture masquerading as fact is paraded instead for blank check acquiescence. Gone is the science, the mission and any hope for the public investment. Clearly it is noted. People had all the reason to act. But failed imagination bias for the greatest telescope vulnerability cost everyone involved their jobs.
Dumb
In other words.. (Score:2)
Inspectors were surprised when Arecibo collapsed because they missed something that led to the collapse.
Really? That's newsworthy? Of course they missed the cause of the collapse, if they caught the cause before it collapsed, they wouldn't have been surprised when it collapsed!
Now, if they saw the flaw and ignored it, THAT would be newsworthy...
Puerto... (Score:2)
...Rico. Arecibo antenna is now garbage.
moot point and shifting blame... (Score:2)
the inspectors knew of the slippage, it wasn't missed as the title indicates.. they just didn't take it as seriously as one would have hoped for in hindsight. But they knew the thing was likely to fail... after age, hurricanes, damage, lack of maintenance, and materials failing well below tolerances... this was NOT a surprise...
the cables were installed 60-70 years ago... virtually no maintenance budget... one of the cables snapped at 60% of rated load... so there is that... and the fact the plugs slipped
Video Tour of Non-broken Scope (Score:3)
You get to see it all. [youtube.com]
Went down a wormhole just one recent Saturday morning, found this as I was looking for inspiration for an art project. The under part of it was also interesting to me. YMMV.