The Arecibo telescope's 900-ton platform has crashed into its disk below and destroyed the iconic radio observatory

• The Arecibo Observatory's iconic radio telescope collapsed Tuesday morning.
• The telescope's suspended platform, which weighed 900 tons, crashed into its bowl-shaped disk below. The tops of three support towers snapped off as the platform fell.
• Arecibo's destruction was not unexpected: The telescope was damaged beyond repair after two cables broke in August and November.
• Losing Arecibo deals a major blow to efforts to protect Earth from hazardous asteroids and search for signs of intelligent alien life.
• However, pending major funding, a new state-of-the-art facility could be built in its place.

The second-largest radio telescope in the world is no more.

The Arecibo Observatory's 1,000-foot-diameter telescope collapsed at about 7:55 a.m. Tuesday in Puerto Rico. The telescope's 900-ton platform, which was suspended 450 feet in the air to send and receive radio waves, crashed into its disk below, pulling down with it the tops of three support towers.

"Friends, it is with deep regret to inform you that the Arecibo Observatory platform has just collapsed," Deborah Martorell, a meteorologist in Puerto Rico, tweeted in Spanish on Tuesday morning.

Before-and-after images show how the platform fell.

—Deborah Martorell (@DeborahTiempo) December 1, 2020

The collapse was not unexpected: Following two cable breaks in August and November, experts determined that the radio telescope was so structurally unsound that it had to be decommissioned.

On November 19, the National Science Foundation, which owned the telescope, tasked engineers with deconstructing it. That was supposed to take about five or six weeks, but the iconic telescope couldn't last that long.

The foundation published video footage of the collapse on Thursday, captured from a nearby control tower.

—Morgan McFall-Johnsen (@MorganMJohnsen) December 3, 2020

Nobody was injured in the collapse, the NSF said in a statement, since the area had been cleared after the second cable failure.

"I feel sick in my stomach," Ramon Lugo, the director of the Florida Space Institute at the University of Central Florida, who managed the telescope, told Science on Tuesday. "Truthfully, it was a lot of hard work by a lot of people trying to restore this facility. It's disappointing we weren't successful. It's really a hard morning."

'It's like losing someone important in your life'

In its 57 years of operation, the Arecibo telescope hunted for hazardous near-Earth asteroids, searched for signs of alien life, and discovered the first planet beyond our solar system.

In 1974, Arecibo beamed the most powerful broadcast Earth has ever sent to communicate with aliens if they're out there. In 2016, it detected the first repeating fast radio bursts - mysterious space signals that scientists now think come from dead stars.

But Arecibo's woes began in August, shortly after Tropical Storm Isaias passed over Puerto Rico. A 3-inch-thick auxiliary cable popped out of its socket on one of the telescope's three towers and crashed into the 1,000-foot reflector dish below. It tore a 100-foot gash in the panels.

Then in early November, just before repairs were set to begin in earnest, a 15,000-pound main cable from the same tower broke and crashed into the dish. Engineers had thought the structure was still strong enough to avoid a second disaster - and this cable was carrying just 60% of its estimated load capacity - but the new failure proved them wrong. They decided they could no longer trust any of the remaining cables and would decommission the facility.

Both failed cables were supporting the enormous metal platform hanging over the dish. Experts predicted in November that if another cable from the same tower were to fail, the platform would fall with it. That is indeed what happened on Tuesday morning.

"When I learned of the news, I was totally devastated," Abel Mendez, the director of the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, told Business Insider in November.

Mendez had been around the observatory since he was 10 years old and worked with it professionally for the past decade.

"It's hard to take. It's like losing someone important in your life," he said. "Yeah, 2020 - it's not good."

The US has lost its best asteroid hunter and alien seeker

The loss of Arecibo's telescope is a major blow to humanity's search for alien life, our ability to defend the planet from asteroids, and the entire field of radio astronomy.

Though Arecibo didn't discover dangerous space rocks, it was instrumental in investigating them, Mendez said: The observatory could ping such objects with radar to decrypt their shape, rotation, surface features, and trajectory through space.

Without that data, it's much harder to know whether an asteroid is hurtling toward Earth.

Arecibo's massive dish antennae, built into a depression on the Puerto Rican jungle floor, pinged those objects by reflecting radio waves from space to its suspended platform.

The collapse of the platform, and the resulting damage to the dish below, makes that data collection impossible.

Other NSF facilities - the National Radio Astronomy Observatory in Virginia and the Green Bank Observatory in West Virginia - could take on some of Arecibo's data collection. However, Mendez said Green Bank was only 10% to 20% as sensitive to weak radio signals as Arecibo. So he thinks the telescope's death effectively ends the US's chance to develop a comprehensive project to search for radio waves from alien technology.

"The only place that we have to do something like that, that'd be sensitive or more sensitive than Arecibo, is now FAST in China," Mendez said, referring to the Five-hundred-meter Aperture Spherical Radio Telescope in the Guizhou province. "The United States lost all that capability because it doesn't have Arecibo."

Arecibo and FAST, Mendez said, were Earth's "two big eyes" in radio astronomy.

"If you are monitoring a source of interest which is in the weak radio spectrum, you need two big radio telescopes: one pointing toward something during the day, and the other through the nighttime," he said.

"If you lose Arecibo, then you lose the ability to monitor - 24 hours a day - a faint source of radio signals," he said, adding, "Now we just have one eye."

'Rebuilding is a choice'

With Arecibo's end could come a new beginning.

Already, astronomers are sharing ideas for building a state-of-the-art facility in Arecibo's place - though this would require the incoming Biden administration to push for such an effort and Congress to fund it.

"A rebuilt Arecibo would be an important scientific instrument in many realms, notably gravitational waves," Saavik Ford, an astrophysicist at the City University of New York and the American Museum of Natural History, wrote to an astronomy email list before the observatory's downfall.

She added: "Structural collapse is imminent and leaves us with no options there - but rebuilding is a choice which would yield both economic benefits and (importantly) scientific advances."

This story has been updated with new information. It was originally published at 10:49 a.m. ET on December 1, 2020.

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