The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC), is (or was, as the case may be) an observatory in Arecibo, Puerto Rico, owned by the US National Science Foundation (NSF).

The observatory’s main instrument was the Arecibo Telescope, a 305-metre spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted 150 metres above the dish.

It was completed in 1963 and was the world’s largest single-aperture telescope, until it was unseated in 2016 by the 500-metre Aperture Spherical Telescope (FAST) in China.

Then, towards the start of November this year, following two cable breaks, the NSF was making plans to dismantle it due to safety concerns.

Gravity and wear and tear on the support cables beat them to it.

Arecibo’s Operations Control Centre had cameras trained on the structure, as well as a couple of drones watching it in case things went south.

That they dud, and in a big way, when the cables snapped and everything collapsed.

Per The Verge, footage of the collapse was captured by the control centre and a drone.

The video, captured on December 1st, shows the moment when support cables snapped, causing the massive 900-ton structure suspended above Arecibo to fall onto the observatory’s iconic 1,000-foot-wide dish.

Keep the sound on:

As you can see, multiple cables snapped at once, so there was no salvaging it.

“The cables that go from the top of Tower 4 to the platform — they’re very faint in the camera view but they’re there,” said John Abruzzo, a contractor at engineering consulting firm Thornton Tomasetti, hired by the University of Central Florida. “And so it’s those cables that fail near the tower top first, and then once those fail, the platform then loses stability and starts to come down,” Abruzzo said, describing the first video from the control center.

While the collapse didn’t come as a surprise, it’s still a sad day for science.

“With regards to replacement, NSF has a very well defined process for funding and constructing large scale infrastructure — including telescopes,” Ralph Gaume, director of NSF’s division of astronomical sciences, said.

“It’s a multi-year process that involves congressional appropriations, and the assessment and needs of the scientific community. So it’s very early for us to comment on the replacement.”

RIP Arecibo, you served us well.

[source:verge]