dzdt43 minutes ago
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.
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snyphera day ago
(2024). Here's the report 'Failure Analysis of the Arecibo Observatory 305-Meter Telescope Collapse'
jacquesm2 hours ago
This is the better link. The meat is on page 2.
metalman18 hours ago
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.
ceejayoz2 hours ago
> Long-term low-current electroplasticity, induced by the electromagnetic waves from the Arecibo telescope itself, may have sped up the zinc creep, it says.
I presume we aren't using most bridges as interstellar antennas.
tejtm34 minutes ago
> I presume we aren't using most bridges as interstellar antennas.
any like area of metal will receive as much interstellar emissions but I guess they did run a MW transmitter sometimes.
AngryDataan hour ago
No, but there is a lot of potential for large structures to act like an accidental antenna and/or receive low level voltages from the environment or other equipment.
Likely won't matter in most cases, but there could be a few disasters waiting around.
xattt2 hours ago
That’s what the government (… and most rational people) wants you to think.
grim_io42 minutes ago
how could the government control the birds without using bridges as antennas?!
msandford2 hours ago
They also mentioned that this is the first example of the unknown phenomena that caused the creep. This technology has been in use quite successfully for more than 100 years.
sanex2 hours ago
Bridges probably shouldn't be subject to the same electromagnetic radiation that gets focused by the telescope though so ideally not a problem there.
drum55an hour ago
Where the cables were there’s nothing focused, just wires, it was outside of the dish.
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