Radio telescope as tall as a four-storey building collapses in Puerto Rico

A satellite image by 2020 Maxar Technologies shows the damaged radio telescope at the Arecibo Observatory in Puerto Rico. Photo / AP

A huge, already damaged radio telescope in Puerto Rico that has played a key role in astronomical discoveries for more than half a century completely collapsed today.

The telescope's 900-tonne receiver platform and the Gregorian dome — a structure as tall as a four-storey building that houses secondary reflectors — fell onto the northern portion of the vast reflector dish more than 120m below.

The United States National Science Foundation had earlier announced that the Arecibo Observatory would be closed. An auxiliary cable snapped in August, causing a 30m gash on the 305m-wide 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 sounded like a rumble. I knew exactly what it was," said Jonathan Friedman, who worked for 26 years as a senior research associate at the observatory and still lives near it. "I was screaming. Personally, I was out of control.... I don't have words to express it. It's a very deep, terrible feeling."

Friedman ran up a small hill near his home and confirmed his suspicions: A cloud of dust hung in the air where the structure once stood, demolishing hopes held by some scientists that the telescope could somehow be repaired.

The collapse wasn't a surprise because many of the wires in the thick cables holding the structure snapped over the weekend, Ángel Vázquez, the telescope's director of operations, told AP.

"It was a snowball effect," he said. "There was no way to stop it.... It was too much for the old girl to take."

Additional details regarding the collapse at the Arecibo Observatory’s 305-meter telescope are available now at NSF's site: https://t.co/dCYLolC22L

Engineers are on-site. Top priorities are maintaining safety at the site and assessing damage. pic.twitter.com/9mqnBx3dcU

— National Science Foundation (@NSF) December 1, 2020

He said that it was extremely difficult to say whether anything could have been done to prevent the damage that occurred after the first cable snapped in August.

"The maintenance was kept up as best as we could," he said. "[The National Science Foundation] did the best that they could with what they have."

However, observatory director Francisco Córdova, said that while the NSF decided it was too risky to repair the damaged cables before today's collapse, he believes there had been options, such as relieving tension in certain cables or using helicopters to help redistribute weight.

Installing a new telescope would cost up to US$350 million, money the NSF doesn't have, Vázquez said, adding it would have to come from the US Congress.

"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 centre and restore operations at the observatory's remaining assets, including its two LIDAR facilities used for upper atmospheric and ionospheric research, including analysing cloud cover and precipitation data. The LIDAR facilities are still operational, along with a 12m telescope and a photometer used to study photons in the atmosphere, Vázquez said.

The telescope was built in the 1960s with money from the Defence 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.

- AP