The U.S. National Science Foundation has released dramatic video footage showing the failure of a third cable helping support the Arecibo Observatory’s 900-ton instrument platform, trigging the huge lattice-work platform’s catastrophic plunge onto the radio telescope’s 205-metre (1,000-foot) dish some 137 metres (450 feet) below.
The cable’s failure, following the earlier failures of two others on 6 November and 10 August, put so much strain on the suspension system that the remaining cables on that same support tower failed as well. As that side of the instrument platform began falling, cables stretching from two other support towers also failed. The tops of the towers themselves broke away in the aftermath and plunged down toward the dish.
The video below shows the collapse from two perspectives, one from a camera on the observatory’s control center and the second from a drone that was stationed just above the support tower anchoring the failing cables:
No one was inside designated danger zones at the time of the collapse and no injuries were reported.
On 19 November, the NSF announced that the observatory would be decommissioned and demolished in the wake of engineering reports that concluded the support system could not be safely repaired and that the remaining cables holding up the instrument platform could fail at any moment. Engineers were assessing how to go about a safe demolition when the third cable snapped.