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Arecibo Observatory Cables Put To the Test

October 26, 2021
One of the cables from Arecibo Observatory brought to Lehigh University for testing. Thornton Tomasetti
An instrumented cable and socket being prepared for testing. In this example, the instrumented testing will help determine why this cable slipped from its socket by about 1 inch. Thornton Tomasetti
This test rig, in the Fritz Engineering Laboratory at Lehigh, will stretch the cable to help determine the mode of failure. This device is often used to test cables for suspension bridges. Thornton Tomasetti

Why did the Arecibo radio telescope collapse? It’s a simple question that has a complicated answer. To help find out, we’re conducting full-size tests, with the help of LPI (a SOCOTEC Company) and Lehigh University, of the actual Arecibo cables.

During our investigation, we found that some cables that held up the telescope had slipped out of their sockets from one-half inch to two inches or more. Why did the slip occur, and why had some slipped much more than others? This testing, using the cables and sockets recovered from Arecibo, focuses on how the cable is installed in its socket. In this mock-up, we will apply many cycles of tension/release to the cable to simulate the stress it underwent when the telescope was in use.

As with many kinds of testing, one test rarely gives a definitive answer but points investigators in a direction of further inquiry to arrive at a most plausible conclusion.