The destruction of the 57-year-old, 1,000-foot-wide radio telescope dish at the Arecibo Observatory in Puerto Rico on December 1 was a loss for science, pop culture, and preservation (the observatory was listed on the National Register of Historic Places in 2008), and emblematic of America’s crumbling infrastructure, laid low by repeatedly deferred maintenance.
Thanks to the National Science Foundation (NSF), which owns the observatory in Arecibo, we can now see the exact moment that the 900-ton instrument platform came crashing down, falling 450 feet and smashing the dish below.
From the early-morning video, the platform (which was being monitored for just this kind of catastrophic collapse), seems fine at first before the first set of support cables fail, triggering a cascading collapse. The platform, and the tops of the three surrounding support towers, then topples in seconds and falls into the natural depression containing the dish.
(Courtesy of the Arecibo Observatory, a U.S. National Science Foundation facility)
From a drone’s-eye view (already in the air to survey the damaged cables, a section of frayed wire can be seen right at the beginning of the clip), the 3.5-inch steel support cables suddenly snap and unravel one after another, though it’s unclear if the initial failure occurred at that particular tower. Thankfully, everything appears to have fallen directly down into the dish and away from the rest of the facility. There were no reported injuries, either, as observatory employees had been evacuated as part of the dish decommissioning plan announced in mid-November.
The trouble at Arecibo began in early August when an auxiliary support cable for the instruments platform slipped out of its socket and cut a 100-foot-long gash across the fragile dish. That kicked off a negative feedback loop as three months later, due to the additional strain, one of the main support cables (one of twelve, as four main cables connected the platform to the three support towers) snapped, putting even more strain on the remaining lines. Although the cable was carrying below its maximum rated capacity, its breakage raised fears that it, and the other support lines, were degraded and incapable of carrying appropriate loads.
An engineering report from Thornton Tomasetti confirmed that fear, and a decommissioning and demolition were ordered while it was still feasible (which obviously didn’t happen). While the collector dish’s loss is a tragic one, especially for its historic value, it was usurped as the largest single-aperture telescope in the world in 2016 by China’s Five-hundred-meter Aperture Spherical Telescope (FAST).