Zinc creep in cable spelter sockets brought down the Arecibo telescope in 2020

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.

In case you didn't see the video of collapse at the time (don't miss the drone footage which starts at 0:55):

>Watch the Arecibo Observatory's catastrophic collapse!

https://www.youtube.com/watch?v=u34uwFOCM-4

(2024). Here's the report 'Failure Analysis of the Arecibo Observatory 305-Meter Telescope Collapse'

https://www.nationalacademies.org/read/26982/chapter/1#vi

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not good, not good at all, as this is how ALL bridges and towers are supported, the basic engineering bieng that any cable end will be stronger than the cable itself and will last longer than the cable itself, except now, when it isn't, not good, not easy to inspect, not easy to service.

Well, that and the reductions in funding.