We might finally know what destroyed Arecibo’s massive telescope

Nearing four years ago, the Arecibo Telescope’s instrument platform collapsed and destroyed the massive radio telescope’s dish below. What caused it has still remained a massive mystery, but a new study might finally shed some light on what could have caused the loss of one of the National Science Foundation’s most important research tools.

The Arecibo Radio Telescope was located in Puerto Rico, inside a natural sinkhole. The 1,000-foot wide dish was made of metal sheets, perfect for bouncing radio and radar waves up into the suspended instrument platform above it. That platform weighed 900 tons and was hung using steel cables from three concrete towers.

It was a massive structure and was one of only a few radio and radar telescopes of that size that could both receive and send radio transmissions. While this meant that it was a good tool for scientists searching for intelligent life outside our solar system, it was even more important for near-Earth asteroid searching.

The platform suspended above the dish had several different instruments that could be used, depending on the type of astronomy or research you were doing. One of those was one of the most powerful radar systems on the planet. This produced very large amounts of electromagnetic radiation but allowed close studies of supermassive black holes, asteroids, and distant galaxies.

University of Wisconsin’s Habib Tabatabai proposes that the very instrument that made the telescope so useful could have played a role in its demise. A phenomenon called “zinc creep,” created by the powerful S-band planetary radar system’s current passing through the support cables and into the ground, likely caused the same cables to fail.

But where does zinc come into play? Those cables we talked about go from the instrument platform to the support towers, then down into joints embedded in the ground. These joints are created by pouring molten zinc into steel sockets, which have been stated to have a basically zero chance of pulling out. However, in Arecibo’s case, they did.

The current flowing through the zinc has been shown to weaken it; however, those studies were in industrial scenes with much stronger currents over shorter amounts of time. It is believed that lower currents over a long period of time might cause the same effect.

“It is something that we make clear is not proven,” Tabatabai told skyandtelescope.org. “But we could not disprove it either, and we do say that this is the only plausible explanation that we could note that would address all these observed patterns.”

While movements to rebuild the now destroyed telescope were created to pressure policymakers, it was decided to retire the telescope’s mission at Arecibo and dismantle it.