All the reported experimental zinc electroplasticity (EP) data were developed at current densities orders of magnitude higher than those possibly present in the Arecibo Telescope but measured in laboratory experimental periods that were orders of magnitude shorter than the telescope's socket zinc service.
There are no reported experimental data concerning low-current, long-term EP, which the committee has lumped together under the term "LEP", affecting zinc's creep mechanisms over decades.
The timing and patterns of the Arecibo Telescope's socket failures make the LEP hypothesis the only one that the committee could find that could potentially explain the failure patterns observed.
Accelerated aging is, as far as I know, pretty much standard in the industry. Nobody can wait 20 years to find out if a certain material is good enough or not.
However, the real failure seems to be the lack of urgency when they signs started to show up:
Upon reflection, the unusually large and progressive cable pullouts of key structural cables that could be seen during visual inspection several months and years before the M4N failure should have raised the highest alarm level, requiring urgent action. The lack of documented concern from the contracted engineers about the inconsequentiality of the cable pullouts or the safety factors between Hurricane Maria in 2017 and the failure is alarming.
> The lack of documented concern from the contracted engineers about the inconsequentiality of the cable pullouts or the safety factors between Hurricane Maria in 2017 and the failure is alarming.
This is crazy. Basically cables were pulling out for months and years and no one raised the alarm? In many industries that could be a criminal or career ending malpractice. Are the "contracted engineers" liable?
Hmmm. I was just looking this over a couple of days ago.
On Nov 19 2020, NPR was already reporting that "Sean Jones, Director for the Mathematical and Physical Sciences Directorate at the NSF, said the telescope will be dismantled. ... after receiving ... the engineering assessments, we have found no path forward that would allow us to do so safely..." https://www.npr.org/2020/11/19/936677582/world-renowned-arec...
In retrospect, it seems that, -at its age- the design got in the way of repairs. The scope made possible a lot of great finds in its day, but it'd become too weak to save.
You go to school and learn that 2+2=4. You get a consulting job and learn 2+2= whatever the client says it is.
I wouldn’t jump to the conclusion that the consulting engineer was incompetent. Sometimes a bureaucrat tells you to sharpen your pencils and come back with the answer That fits the budget they have if you want to keep your professional services contract going.
In chapter 5 they go into how the ownership was transferred to the University of Central Florida (UCF) at the start of 2018, after the hurricanes in 2017.
It seems unlikely that UCF had adequate time and resources to review and understand the Arecibo Telescope's original 1963 design, the 1974 upgrade, the structural inspection and maintenance records produced for nearly 50 years, [...] and the key factors, such as the wire breaks and cable pullout of the sockets and their significance on the strength and integrity of the structure.
The measured cable pullout may have appeared "normal" to [the UCF staff] and was not on their radar as signs of structural distress. The lack of concern may be because a small cable pullout was present from the beginning, and no one in authority had previously raised an alarm
But yeah, seems weird no-one of the contractors tried to raise an alarm.
Since the design had a factor of safety of 2, and no other cables exhibited pull out at such high safety factors, checking such things might not even have been on the checklist.
> Basically cables were pulling out for months and years and no one raised the alarm?
And what if they did? Then what? My guess is the conversation went something like this:
"Okay, cables are pulling out. Raising this issue will not magically make money appear to fix it as nobody wants to fund this. Tell me, how much do you like your job? If you flag this, you may lose your job directly and if the project gets shut down you may lose your job indirectly. So, how about we bury this as much as possible, cross our fingers and bank as much money as possible in the meantime, eh?"
The reliance by the consultants (before and after the first cable failure in 2020) on a perceived allowable pullout of
one-sixth of the cable diameter, which should only be seen at loading at 80 percent of ultimate cable strength, does
not align with the AASHTO M 277 standard guidance. The committee, therefore, disagrees with the suggestion
made in the Thornton Tomasetti, Inc. (TT) 2022 report, Arecibo Telescope Collapse: Forensic Investigation,13 to
use the D/6 limit as a threshold for slip monitoring.
As a sailor that uses similar fittings in sailboat rigging… the idea of not treating a cable pullout from a terminal as an emergency is absurd. If that happened on a sailboat rig I’d assume it had a remaining strength of zero and will fall in seconds or less- and take the most rapid possible action to keep the structure from coming down by deloading the shroud and rigging an emergency replacement.
I would be curious if there are any accounts/reports of people working there - especially engineers - that could verify the claims of no alarm being raised when the first structural failures started showing up. It is often the case that people on the ground report such things but when "reports" are written for the higher ups, facts get "massaged" according to expectations.
I was on the suspended section about a year before collapse - everyone could tell it was about to fail. Visible stress in rusty beams, old cables, and failing concrete. I think it just came down to underfunding at the end of the day - there was no money available to ask for even if the alarms were louder.
And for most applications it was obsoleted by the larger new telescope in china, so there was no large push to turn that ship around from the wider scientific community.
>normally bulletproof service history of zinc spelter cable terminations in structures.
They're relatively new, they're relatively expensive (which saves them from being used in the worst of the applications) and like most things inherent to steel cable and whatnot they tend to get employed in situations where safety factors are generous. Don't count your chickens before they hatch.
Even if I am not a radio astronomer, this instrument was unique in nature and still in use for very specific observations and until the very end of its operation was able to deliver data. It is disheartening to learn that it was indeed due to gross maintenance negligence (as assumed originally by many) that the final fatal failure occurred, when potentially the structure could have been salvaged.
Losing Arecibo was, as I understand it, a big blow to the NANOGrav experiment, which is looking for very low frequency gravitational waves by measuring pulsar timing variations[1].
Albeit having limited field of view the Arecibo Telescope was very sensitive[2], and so could see pulsars that the other telescopes they used could not. And the longer they could collect data from a set of pulsars the lower frequency waves they could probe.
My uninformed recollection from when the warning signs were raised, is there was not even budget to perform emergency maintenance, and they were resigned to the inevitable collapse.
I worked and did research atobservatory for my PhD - you are exactly correct. It was well known to the scientists and onsite engineers that a collapse was imminent, for years. Ironically, prior to the collapse the agency responsible for funding performed a study to see would need to do to stop supplying money to the observatory, and found that due to environmental impact, it would actually be more expensive to stop funding. After that study we all suspected that the agency was just waiting for decay or a natural disaster to do the dirty work for them
That's not what the report says. There was ~$14 million allocated for repairs in 2-18 after Hurricane Maria, but the cable sockets weren't identified as needing repairs until the first one failed. The problem wasn't the money, it was the failure to identify the problem. See page 28/29.
Arecibo did high power transmit for radar imaging of asteroids/comets/the sun/etc and ionosphere studies, among other things. FAST is not capable of transmit (it was not designed for it and the suspended receiver mass is much lower). Also, FAST has a RF-noise emitting theme park built just outside of it's grounds.
The uniqueness of Arecibo was this transmit coupled with such a large aperture (so small pattern on sky).
Ah, no, like most journals (although NAP is not stricly a journal, PNAS is), there isn't a direct PDF link (OP: try to click that on a clean browser and you'll be disappointed).
Readit News
All the reported experimental zinc electroplasticity (EP) data were developed at current densities orders of magnitude higher than those possibly present in the Arecibo Telescope but measured in laboratory experimental periods that were orders of magnitude shorter than the telescope's socket zinc service.
There are no reported experimental data concerning low-current, long-term EP, which the committee has lumped together under the term "LEP", affecting zinc's creep mechanisms over decades.
The timing and patterns of the Arecibo Telescope's socket failures make the LEP hypothesis the only one that the committee could find that could potentially explain the failure patterns observed.
Accelerated aging is, as far as I know, pretty much standard in the industry. Nobody can wait 20 years to find out if a certain material is good enough or not.
However, the real failure seems to be the lack of urgency when they signs started to show up:
Upon reflection, the unusually large and progressive cable pullouts of key structural cables that could be seen during visual inspection several months and years before the M4N failure should have raised the highest alarm level, requiring urgent action. The lack of documented concern from the contracted engineers about the inconsequentiality of the cable pullouts or the safety factors between Hurricane Maria in 2017 and the failure is alarming.
This is crazy. Basically cables were pulling out for months and years and no one raised the alarm? In many industries that could be a criminal or career ending malpractice. Are the "contracted engineers" liable?
On Nov 19 2020, NPR was already reporting that "Sean Jones, Director for the Mathematical and Physical Sciences Directorate at the NSF, said the telescope will be dismantled. ... after receiving ... the engineering assessments, we have found no path forward that would allow us to do so safely..." https://www.npr.org/2020/11/19/936677582/world-renowned-arec...
In retrospect, it seems that, -at its age- the design got in the way of repairs. The scope made possible a lot of great finds in its day, but it'd become too weak to save.
I wouldn’t jump to the conclusion that the consulting engineer was incompetent. Sometimes a bureaucrat tells you to sharpen your pencils and come back with the answer That fits the budget they have if you want to keep your professional services contract going.
It seems unlikely that UCF had adequate time and resources to review and understand the Arecibo Telescope's original 1963 design, the 1974 upgrade, the structural inspection and maintenance records produced for nearly 50 years, [...] and the key factors, such as the wire breaks and cable pullout of the sockets and their significance on the strength and integrity of the structure.
The measured cable pullout may have appeared "normal" to [the UCF staff] and was not on their radar as signs of structural distress. The lack of concern may be because a small cable pullout was present from the beginning, and no one in authority had previously raised an alarm
But yeah, seems weird no-one of the contractors tried to raise an alarm.
And what if they did? Then what? My guess is the conversation went something like this:
"Okay, cables are pulling out. Raising this issue will not magically make money appear to fix it as nobody wants to fund this. Tell me, how much do you like your job? If you flag this, you may lose your job directly and if the project gets shut down you may lose your job indirectly. So, how about we bury this as much as possible, cross our fingers and bank as much money as possible in the meantime, eh?"
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The reliance by the consultants (before and after the first cable failure in 2020) on a perceived allowable pullout of one-sixth of the cable diameter, which should only be seen at loading at 80 percent of ultimate cable strength, does not align with the AASHTO M 277 standard guidance. The committee, therefore, disagrees with the suggestion made in the Thornton Tomasetti, Inc. (TT) 2022 report, Arecibo Telescope Collapse: Forensic Investigation,13 to use the D/6 limit as a threshold for slip monitoring.
And for most applications it was obsoleted by the larger new telescope in china, so there was no large push to turn that ship around from the wider scientific community.
Everyone working in large corporations knows this.
They're relatively new, they're relatively expensive (which saves them from being used in the worst of the applications) and like most things inherent to steel cable and whatnot they tend to get employed in situations where safety factors are generous. Don't count your chickens before they hatch.
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Albeit having limited field of view the Arecibo Telescope was very sensitive[2], and so could see pulsars that the other telescopes they used could not. And the longer they could collect data from a set of pulsars the lower frequency waves they could probe.
[1]: https://nanograv.org/news/15yrRelease
[2]: https://pirsa.org/20100068 Moving Closer to a Detection of nHz-frequency Gravitational Waves with NANOGrav (Arecibo details at around 10:20)
https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...
The uniqueness of Arecibo was this transmit coupled with such a large aperture (so small pattern on sky).
[1] https://youtu.be/3oBCtTv6yOw
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