Associated Press

Observatory had been set to close after damage in August
Scientists and Puerto Ricans mourn loss of historic facility

The ruined Arecibo radio telescope after cables supporting its suspended instrument platform broke, sending it crashing down into the disc. Photograph: Ricardo Arduengo/AFP/Getty Images

A huge radio telescope in Puerto Rico that has played a key role in astronomical discoveries for more than half a century collapsed on Tuesday, officials said.

The telescope’s 900-ton receiver platform fell onto the reflector dish more than 400 feet below.

The US National Science Foundation had earlier announced that the Arecibo Observatory would be closed. An auxiliary cable snapped in August, causing a 100ft gash on the 1,000ft-wide (305m) reflector dish and damaged the receiver platform that hung above it. Then a main cable broke in early November.

The collapse stunned many scientists who had relied on what was until recently the largest radio telescope in the world.

“It’s a huge loss,” said Carmen Pantoja, an astronomer and professor at the University of Puerto Rico who used the telescope for her doctorate. “It was a chapter of my life.”

Scientists worldwide had been petitioning US officials and others to reverse the NSF’s decision to close the observatory. The NSF said at the time that it intended to eventually reopen the visitor center and restore operations at the observatory’s remaining assets, including its two Lidar facilities used for upper atmospheric and ionospheric research, including analyzing cloud cover and precipitation data.

The telescope was built in the 1960s with money from the US defense department amid a push to develop anti-ballistic missile defenses. It had endured hurricanes, tropical humidity and a recent string of earthquakes in its 57 years of operation.

The telescope has been used to track asteroids on a path to Earth, conduct research that led to a Nobel prize and determine if a planet is potentially habitable. It also served as a training ground for graduate students and drew about 90,000 visitors a year.“

The space telescope in 2006, then as damage progressed in 2020. Photograph: Ricardo Arduengo/AFP/Getty Images

“I am one of those students who visited it when young and got inspired,” said Abel Mendez, a physics and astrobiology professor at the University of Puerto Rico at Arecibo who has used the telescope for research. “The world without the observatory loses, but Puerto Rico loses even more.”

He last used the telescope on 6 August, just days before a socket holding the auxiliary cable that snapped failed in what experts believe could be a manufacturing error. The National Science Foundation, which owns the observatory that is managed by the University of Central Florida, said crews who evaluated the structure after the first incident determined that the remaining cables could handle the additional weight.

But on 6 November another cable broke.

A spokesman for the observatory said there would be no immediate comment, and a spokeswoman for the University of Central Florida did not return requests for comment.

Scientists had used the telescope to study pulsars to detect gravitational waves as well as search for neutral hydrogen, which can reveal how certain cosmic structures are formed. About 250 scientists worldwide had been using the observatory when it closed in August, including Mendez, who was studying stars to detect habitable planets.

“I’m trying to recover,” he said. “I am still very much affected.”