--- title: Zinc creep in cable spelter sockets brought down the... description: Zinc creep in cable spelter sockets caused the 2020 collapse of the Arecibo Observatory's 57-year-old telescope, a National Academies report finds. The failure... canonical: https://daily.dev/posts/zinc-creep-in-cable-spelter-sockets-brought-down-the-arecibo-telescope-in-2020-hfj6jwmpg twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Zinc creep in cable spelter sockets brought down the Arecibo telescope in 2020 | daily.dev og:description: Zinc creep in cable spelter sockets caused the 2020 collapse of the Arecibo Observatory's 57-year-old telescope, a National Academies report finds. The failure... og:url: https://daily.dev/posts/zinc-creep-in-cable-spelter-sockets-brought-down-the-arecibo-telescope-in-2020-hfj6jwmpg og:image: https://api.daily.dev/og/posts/Hfj6JwmPg.png og:image:alt: Zinc creep in cable spelter sockets brought down the Arecibo telescope in 2020 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Zinc creep in cable spelter sockets brought down the Arecibo telescope in 2020 **[Hacker News](https://daily.dev/sources/hn)** · 3 min read · 0 upvotes · 0 comments ## Summary Zinc creep in cable spelter sockets caused the 2020 collapse of the Arecibo Observatory's 57-year-old telescope, a National Academies report finds. The failure sequence began with Hurricane Maria, over three years before the collapse. Zinc inside the cable sockets gradually lost its grip, letting cables pull out until the platform fell into the 305-meter reflector dish. The report calls it the first documented case of long-term zinc-induced creep failure despite a long history of usage over a century. It also offers one possible explanation, that electromagnetic waves from the telescope itself may have accelerated the creep through low-current electroplasticity, and recommends that NSF make explicit funding provisions for ongoing condition maintenance and monitoring. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What caused the Arecibo Observatory telescope collapse in 2020 Zinc creep in the cable spelter sockets was the root cause, according to a National Academies of Sciences, Engineering, and Medicine report. The zinc inside the sockets holding the support cables gradually lost its grip, letting cables pull out until the suspended platform fell into the 305-meter reflector dish. The failure sequence began with Hurricane Maria, over three years before the collapse. _Engineers researching structural failure cases can track detailed technical analyses like this one on daily.dev._ ### Had zinc creep ever caused a cable socket failure before Arecibo No, the report calls it the first documented case of long-term zinc-induced creep failure despite zinc-filled spelter sockets being used for more than a century. Before Hurricane Maria, indications of cable pullout were minimal, but inspections afterward showed large and progressive pullouts that should have prompted remedial action. _Anyone evaluating aging infrastructure risk can follow findings like this on daily.dev._ ### Could the Arecibo telescope's own radio waves have contributed to its collapse Possibly, according to the National Academies report, which proposes long-term low-current electroplasticity induced by the electromagnetic waves from the telescope itself may have sped up the zinc creep in the cable sockets. The report recommends NSF offer the remaining socket and cable sections to researchers for further study. _Readers curious about unusual failure mechanisms can keep up with reports like this via daily.dev._ ## Community take How the wider developer community reacted, aggregated from 1 discussion and 37 comments across hackernews (as of 2026-11-01). **TL;DR:** Discussion largely accepts the report's zinc-creep and electroplasticity explanation but centers on whether the self-induced EM radiation theory holds up, and many argue chronic underfunding and lack of inspection were the real root cause behind the socket failures. **Sentiment:** 5% positive · 25% mixed · 70% skeptical **The case for** - The forensic/report summary is seen as a clear, well-documented technical explanation of exactly how the sockets failed. - Some find it plausible that a structure bathed in the world's most powerful transmitter beam could experience unique accelerated effects not seen elsewhere. **The pushback** - Several argue the EM-acceleration theory is weak since it would predict many more similar 'mystery' collapses elsewhere if true. - Many contend the socket design itself had poor, uneven wire distribution that concentrated stress, independent of any EM effect. - A recurring criticism is that decades of inadequate funding meant known cable slippage and damage were never repaired or bypassed despite being flagged in inspections. - Some note the telescope had already been decommissioned, arguing funding cuts were separate from the collapse, though others push back on that framing. **By community** - hackernews (mixed): People debate the credibility of the electromagnetic-acceleration theory while largely agreeing that years of underfunding and skipped maintenance were the underlying cause of the collapse. **Hottest debate:** Whether the telescope's own electromagnetic radiation plausibly accelerated zinc creep, versus skepticism that this one-off effect explains a failure mode not seen in a century of similar bridge/cable hardware. **Open questions** - Why hasn't this zinc-creep failure mode shown up in other long-serving zinc-spelter cable sockets if EM radiation isn't the real cause? - Why wasn't cable brooming for spelter sockets automated given how safety-critical and widespread the technique is? - Why weren't loop-style terminations used instead of spelter sockets? **Highlights** > The forensic report on the failure of the cable sockets is at https://www.thorntontomasetti.com/sites/default/files/2022-0.... Unlike the linked article this includes detailed diagrams and discussion explaining how these sockets worked and how they failed. My attempt at a quick summary: the Arecibo instruments were held up by heavy steel cables, which are composed of a bundle of 126 to 216 individual wire strands twisted together, where each wire strand is about 1/4 inch diameter. At the cable ends these were anchored in sockets. The socket is conical, widening out towards where the wire ends go. The wire strands of the cable would be separated in a "broom" shape to fill out that conical area, and then the whole thing filled in with molten zinc. The failure mode of these zinc-filled sockets is for an inner core cylinder, about the same diameter as the cable body, to pull out from the socket while outer strands of the cable which are broomed out of that core either snap or pull free from the zinc plug. This failure mode hadn't really been seen prior to the Arecibo collapse, partly because it is a long term process where the zinc slowly flows under stress over decades. > — [dzdt on hackernews · 3 comments](https://news.ycombinator.com/item?id=50322159) > The pictures on page 25 seem to show how this socket design fails. First because they didn't evenly distribute the wires in the socket (seriously??)... And second, the shear on the zinc from the compressed wire bundle is essentially a narrow rectangle in the direction of the cable with almost all the force concentrated in a narrow forward bit, not really distributed evenly through the socket, because of the wire ends splaying outward and not being equally distributed. I guess the idea is the rest of the zinc towards the back provides a counter force on the front part, but there's a whole lot more zinc in the back pulling on a smaller amount in the front. The tight bundle and the conical shape is great for a tight install, but doesn't help distribution of load. Compare to the Golden Gate Bridge wire termination (https://c7.alamy.com/comp/2RY9PKW/golden-gate-bridge-plans-i...). The zinc creep is definitely bad, but it seems made worse by an uneven distribution of load in the socket, in addition to all the other problems... tl;dr once the outer wires break in the socket (in part due to zinc creep, but also potentially more load on them), the "glue" keeping the wire bundle connected to the socket is broken, the former wedge keeping the core in place becomes a straight line, and you have a core ready to pop out. > — [0xbadcafebee on hackernews · 1 comments](https://news.ycombinator.com/item?id=50323360) > I'd summarize it this way: With competent engineering and construction, the (failed at Arecibo) zinc socket cable anchors can be very reliable. Unfortunately, Arecibo's engineering was so-so, and the construction quality was half-assed. With annual inspections (by someone with a passable understanding of cable anchors) the problems at Arecibo could easily have been caught in time to correct. Unfortunately, Arecibo received no such inspections. And this is roughly the pattern for most "sudden" failures of infrastructure. > — [bell-cot on hackernews · 2 comments](https://news.ycombinator.com/item?id=50324253) > > Unfortunately, Arecibo received no such inspections. With or without the inspections, the problems Arecibo faced were of a more serious nature. They are hinted in one of the findings: the non-replacement, repair or bypass of the sockets where large slips were observed. The telescope received minimal funding for maintenance over the two decades prior to the collapse despite sings of increasing damage observed in the various inspections. A lot of factors probably contributed to this (political climate, the dropping importance of Arecibo compared to other science instruments and missions, and so on) but the result was that the structure was left with slow but sure decay. I met a couple of people who worked with the telescope including on location and they told me that the general feeling among the people who had this on their minds (most people who ever had anything to do with Arecibo cared about the science not the instrument) was that the decay was slow but certain and catastrophic failure was bound to happen sooner or later. Like a car receiving no maintenance despite the check engine light being on for a decade. > — [buran77 on hackernews · 1 comments](https://news.ycombinator.com/item?id=50324510) > This would predict that we should be seeing far more mystery collapses than we do though > — [jryb on hackernews](https://news.ycombinator.com/item?id=50322565) **Source threads** - [hackernews](https://news.ycombinator.com/item?id=50311045) · 124 points · 37 comments ## Similar posts on daily.dev - [Accidental Climate Engineering With Disintegrating Satellites](https://daily.dev/posts/accidental-climate-engineering-with-disintegrating-satellites-t0ibuuduf) · Hackaday · 0 upvotes · 0 comments - [My Home Fibre Network Disintegrated, Literally](https://daily.dev/posts/my-home-fibre-network-disintegrated-literally-u10vmouqe) · Hacker News · 3 upvotes · 0 comments - [Thunder \+ fiber-optic cabling used for seismic imaging](https://daily.dev/posts/thunder-fiber-optic-cabling-used-for-seismic-imaging-cbkiahldr) · Ars Technica · 0 upvotes · 0 comments - [Space Forge Evaluates In-Orbit Manufacturing Tech](https://daily.dev/posts/space-forge-evaluates-in-orbit-manufacturing-tech-gbzb4k6dy) · IEEE Spectrum · 1 upvotes · 0 comments --- Tags: [#science](https://daily.dev/tags/science) [View this post on daily.dev](https://daily.dev/posts/zinc-creep-in-cable-spelter-sockets-brought-down-the-arecibo-telescope-in-2020-hfj6jwmpg) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Zinc creep in cable spelter sockets brought down the Arecibo telescope in 2020","url":"https://daily.dev/posts/zinc-creep-in-cable-spelter-sockets-brought-down-the-arecibo-telescope-in-2020-hfj6jwmpg","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/zinc-creep-in-cable-spelter-sockets-brought-down-the-arecibo-telescope-in-2020-hfj6jwmpg"},"datePublished":"2026-11-01T04:05:20.860Z","dateModified":"2026-11-01T12:06:18.622Z","description":"Zinc creep in cable spelter sockets caused the 2020 collapse of the Arecibo Observatory's 57-year-old telescope, a National Academies report finds. 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