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The second largest radio telescope in the world collapsed on Tuesday morning.
The 900-ton platform at the Arecibo Observatory, which sent and received radio waves and was suspended 140 meters in the air, crashed into the 1,000-foot-wide (300-meter-wide) disc below. When he fell, he fell with the tops of three surrounding support towers.
Videos of the crash show that it started when the cables that connected the suspended platform to one of the towers broke. Previously, an auxiliary cable on this same tower broke in August, then one of its main cables broke in November.
Since then, the National Science Foundation, which owns Arecibo, had rushed to dismantle the telescope, as it was clear that a complete collapse was possible.
But the platform fell before engineers made much headway in the deconstruction process.
Jonathan Friedman, who has been on the scientific staff of the Arecibo Observatory since 1993, told local media NotiCentro that the collapse sounded like the rumble of an earthquake, train or avalanche.
The video below, captured from a nearby control tower, shows the platform falling at 7:54 a.m. local time. A cable exits the gangway which allowed engineers to access the platform.
The top of the tower where the cables broke, visible in the background, then falls. Then the top of another broken tower descends the hill on the left.
@NSF just shared video footage of the catastrophic collapse of the Arecibo telescope on Tuesday morning. It’s strong.
(Courtesy of Arecibo Observatory, an NSF facility) pic.twitter.com/9zvyrUsfJl
– Morgan McFall-Johnsen (@MorganMJohnsen) December 3, 2020
“As you can see, this was a very violent and unpredictable failure,” Ashley Zauderer, NSF program manager for Arecibo Observatory, said in a briefing Thursday.
In a separate video, drone footage shows the cables snapping and the resulting crash from above. The drone was performing reconnaissance on the telescope platform at the time, as drone surveillance was a key source of information for engineers trying to figure out how to deconstruct the telescope.
Due to the known risk of collapse, no one had been allowed to approach the unstable structure since the fatal rupture of the cable in mid-November.
The neighborhood around the antenna and the three towers had been cordoned off, so no one was injured in the collapse, NSF said.
An inevitable collapse
Arecibo’s downward spiral began in August, when a 3-inch-thick auxiliary cable slipped out of its socket on one of the telescope’s three towers and crashed into the antenna. He tore a 100 foot gash in the panels.
(Arecibo Observatory)
Then the second failure, a broken main cable, surprised telescope officials in November. An engineering assessment then revealed that the remaining cables were likely to break at any time and cause the platform to tip over.
With the structure too unstable to be rescued without risking collapsing on technicians as they worked on repairs, the NSF decided to say goodbye to Arecibo, decommissioning the world’s most iconic radio telescope.
The hole after the second cable failure on November 19, 2020 (Ricardo Arduengo / AFP / Getty Images)
A blow to the search for extraterrestrial life
During its 57 years of operation, Arecibo chased dangerous asteroids close to Earth, searched for signs of extraterrestrial life, and discovered the first planet beyond our solar system.
In 1974, Arecibo aired the most powerful program ever sent by Earth to communicate with potential extraterrestrials. In 2016, it detected the first repeating rapid radio bursts: mysterious space signals that scientists say now come from dead stars.
Arecibo’s massive satellite dishes, built in a depression in the Puerto Rican jungle floor, reflected radio waves from space back to its suspended platform.
Abel Mendez, director of the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, said the loss of the telescope was a blow to humanity’s search for radio waves sent by other life forms . That’s because Arecibo and China’s Five Hundred Meter Aperture Spherical Radio Telescope (FAST) were Earth’s “two big eyes” in radio astronomy.
“If you lose Arecibo, then you lose the ability to monitor – 24 hours a day – a weak source of radio signals,” Mendez told Business Insider before the collapse, adding, “if you are monitoring a source of interest that is in the low radio spectrum, you need two large radio telescopes: one pointing at something during the day and the other at night. “
Other National Science Foundation facilities – the National Radio Astronomy Observatory in Virginia and the Green Bank Observatory in West Virginia – could support some of Arecibo’s data collection, but they are not as sensitive to weak radio signals than was Arecibo.
Dave Mosher contributed reporting.
This article was originally published by Business Insider.
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