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Adiós Arecibo Observatory: America's largest radio telescope faces explosive end after over 50 years of service

The aging structure is too hazardous to repair, engineers say

The Arecibo Observatory, America’s largest radio telescope, is to be blown up after the National Science Foundation decided recent damage has left it too dangerous to repair.

“NSF prioritizes the safety of workers, Arecibo Observatory’s staff and visitors, which makes this decision necessary, although unfortunate," its director, Sethuraman Panchanathan, said in a statement on Thursday.

"For nearly six decades, the Arecibo Observatory has served as a beacon for breakthrough science and what a partnership with a community can look like. While this is a profound change, we will be looking for ways to assist the scientific community and maintain that strong relationship with the people of Puerto Rico."

In 2017 the telescope was severely damaged by Hurricane Maria but things got worse in August when a three-inch auxiliary cable, supporting a 900-ton platform above the telescope's dish, popped out of its socket and came falling down, tearing a 100-foot hole in its metal panels.

The remaining cables struggled to withstand the added strain, and disaster struck again in November after a main cable broke and damaged the dish further. Officials at the University of Central Florida (UCF), who managed the observatory in Puerto Rico, warned it was a race against time to repair the fraying structure.

All efforts to fix the issues, however, have now been abandoned. Thornton Tomasetti, one of the engineering firms hired to investigate the mishap, warned that if another main cable were to fall a catastrophic failure would be very likely.

“While this outcome is not what we had been working towards, and we are disheartened to see such an important scientific resource decommissioned, safety is our top priority," the firm said in a letter addressed to UCF and reviewed by The Register.

Now, the NSF will plan to carry out “controlled demolition” of the 305-meter telescope, following Thornton Tomasetti’s advice. “Although it saddens us to make this recommendation, we believe the structure should be demolished in a controlled way as soon as pragmatically possible," the firm said

Arecibo observatory

Arecibo spared the axe: Iconic observatory vital to science lives on


"It is therefore our recommendation to expeditiously plan for decommissioning of the observatory and execute a controlled demolition of the telescope."

Other parts of the observatory, however, like its LIDAR facility, focused on geospace research, and its visitor center and offsite Culebra facility that monitors Earth’s climate, will reopen after the telescope is decommissioned. Initially, UCF asked for extra funding from the NSF to repair the observatory and launched a formal investigation into what caused the incident.

"Leadership at Arecibo Observatory and UCF did a commendable job addressing this situation, acting quickly and pursuing every possible option to save this incredible instrument," said Ralph Gaume, director of NSF's Division of Astronomical Sciences.

"Until these assessments came in, our question was not if the observatory should be repaired but how. But in the end, a preponderance of data showed that we simply could not do this safely. And that is a line we cannot cross."

Scientists say their goodbyes to the plucky radio telescope

The striking structure has stood in the middle of a national forest in Puerto Rico for over half a century. The telescope paved the way for astronomers to discover the first binary pulsar star and exoplanet, and to analyze numerous potentially hazardous asteroids. It even helped locate the SOHO solar spacecraft, jointly operated by NASA and ESA, when it lost communication with ground control after its gyroscopes failed.

“I have extremely fond memories when I think back to 1998 and how helpful and supportive Donald Campell - who was Director [of the observatory] at that time - and all of the staff at Arecibo were,” Bernhard Fleck, a Project Scientist for the SOHO mission, told El Reg.

“I had contacted Dr Campell late Friday afternoon on July 17, 1998. Two days later on Sunday, 19 July, he was on a plane down to Puerto Rico to oversee these unique radar measurements of a lost spacecraft over 1.5 million kilometers away, I believe a first in space history.”

“The successful detection of SOHO by Arecibo Radar was the turning point in the SOHO recovery and an incredible boost to the morale of the recovery team. Arecibo Radar confirmed that SOHO was still at its predicted location and was not spinning excessively fast.”

Although the loss of America’s largest radio telescope will mean there will be no new observations at the facility, there is still plenty of backlogged data remaining to be analyzed.

“At a time when public interest and scientific curiosity about space and the skies has re-intensified, there remains much to understand about the data that has been acquired by Arecibo,” a UCF’s President Alexander Cartwright told The Register. “Despite this disappointing setback, we remain committed to the scientific mission in Arecibo and to the local community.”

“Critical work remains to be done in the area of atmospheric sciences, planetary sciences, radio astronomy and radar astronomy. UCF stands ready to utilize its experience with the observatory to join other stakeholders in pursuing the kind of commitment and funding needed to continue and build on Arecibo’s contributions to science.” ®

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