Iconic Arecibo Observatory’s 1000-feet telescope is beyond repair, will be demolished amid safety concerns
It is the end of the road for the famed Arecibo Observatory. Home to one of the most powerful telescopes on the planet, the structure has sustained damage that is beyond repair and will be decommissioned and dismantled. The decision by the National Science Foundation (NSF) comes after a second cable failed at the Puerto Rico-based observatory in November.
“Following a review of engineering assessments that found damage to the Arecibo Observatory cannot be stabilized without risk to construction workers and staff at the facility, the US National Science Foundation will begin plans to decommission the 305-meter (1,000 feet) telescope, which for 57 years has served as a world-class resource for radio astronomy, planetary, solar system, and geospace research,” the NSF announced.
The decision comes after NSF evaluated multiple assessments by independent engineering companies that found the telescope structure is in danger of a catastrophic failure and its cables may no longer be capable of carrying the loads they were designed to support. “Several assessments stated that any attempts at repairs could put workers in potentially life-threatening danger. Even in the event of repairs going forward, engineers found that the structure would likely present long-term stability issues,” experts explained.
Stating that the NSF prioritizes the safety of workers, Arecibo Observatory’s staff, and visitors, NSF Director Sethuraman Panchanathan emphasized that this is what makes the decision “necessary, although unfortunate.” “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,” he added.
Constructed in 1963, the iconic telescope consists of a radio dish with a 900-ton instrument platform hanging 450 feet above. The platform is suspended by cables connected to three towers.
Having aided in decades of astronomical discoveries, its loss is a major blow for astronomy. The telescope has contributed to important observations and discoveries in science ranging from spotting the first planet outside our solar system to helping detect the first binary pulsar, which earned its discoverers the Nobel Prize for physics in 1993. It is known for its observations on mysterious blasts of radio waves from deep space and for tracking near-Earth asteroids. It has been used to search for signs of intelligent alien life. The telescope has also featured in films such as the 1995 James Bond movie ‘GoldenEye,’ and the 1997 movie ‘Contact.’
What happened earlier this month?
On August 10, 2020, an auxiliary cable failed, slipping from its socket in one of the towers and leaving a 100-foot gash in the dish below. The facility subsequently suspended most of its operations, and since then, engineers have been examining the telescope. NSF authorized the University of Central Florida, which manages Arecibo, to take all reasonable steps and use available funds to address the situation while ensuring safety remained the highest priority. UCF acted quickly, and the evaluation process was following its expected timeline, considering the age of the facility, the complexity of the design, and the potential risk to workers.
The engineering teams had designed and were ready to implement emergency structural stabilization of the auxiliary cable system. While the observatory was arranging for delivery of two replacement auxiliary cables, as well as two temporary cables, a main cable that supports the observatory broke on November 6, which was unexpected.
Unlike the auxiliary cable that failed at the same facility on August 10, this main cable did not slip out of its socket. It broke and fell onto the reflector dish below, causing additional damage to the dish and other nearby cables. Both cables were connected to the same support tower. No one was hurt. A safety zone was set up around the dish out of an “abundance of caution” and only personnel needed to respond to the incident are allowed on site.
“This is certainly not what we wanted to see, but the important thing is that no one got hurt. We have been thoughtful in our evaluation and prioritized safety in planning for repairs that were supposed to begin Tuesday. Now, this. There is much uncertainty until we can stabilize the structure. It has our full attention. We are evaluating the situation with our experts and hope to have more to share soon,” said Francisco Cordova, the director of the observatory on November 8.
Based on the stresses on the second broken cable -- which should have been well within its ability to function without breaking -- engineers concluded that the remaining cables are likely weaker than originally projected.
Thornton Tomasetti, the engineering firm of record hired by UCF to assess the structure, found that given the likelihood of another cable failing, repair work on the telescope -- including mitigation measures to stabilize it for additional work -- would be unsafe. Stress tests to capture a more accurate measure of the remaining cables’ strength could collapse the structure, assessment suggested. The firm, therefore, recommended a controlled demolition to eliminate the danger of an unexpected collapse. An independent engineering firm hired by NSF hired concurred with Tomasetti’s recommendations.
“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. 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,” explained Ralph Gaume, director of NSF’s Division of Astronomical Sciences.
Areas of the observatory that could be affected by an uncontrolled collapse have been evacuated since the November cable break and will remain closed to unauthorized personnel during the decommissioning. NSF and UCF will work to minimize risk in the area in the event of an unexpected collapse.
What happens now?
The decommissioning process involves developing a technical execution plan and ensuring compliance with a series of legal, environmental, safety, and cultural requirements over the coming weeks. “When all necessary preparations have been made, the telescope would be subject to a controlled disassembly,” said NSF.
The decommissioning plan would focus only on the telescope and is intended to safely preserve other parts of the observatory that could be damaged or destroyed in the event of an unplanned, catastrophic collapse. The aim is to retain as much as possible of the remaining infrastructure of Arecibo Observatory so that it remains available for future research and educational missions.
After the decommissioning, NSF plans to restore operations at assets such as the Arecibo Observatory LIDAR facility -- a geospace research tool -- as well as at the visitor center and offsite Culebra facility, which analyzes cloud cover and precipitation data. NSF would also seek to explore possibilities for expanding the educational capacities of the learning center.
“Some Arecibo operations involving the analysis and cataloging of archived data collected by the telescope would continue. UCF secured enhanced cloud storage and analytics capabilities in 2019 through an agreement with Microsoft, and the observatory is working to migrate on-site data to servers outside of the affected area,” experts revealed.
NSF also aims to work with the Puerto Rican government and other stakeholders and partners to explore the possibility of applying resources from Arecibo Observatory for educational purposes.
“Over its lifetime, Arecibo Observatory has helped transform our understanding of the ionosphere, showing us how density, composition, and other factors interact to shape this critical region where Earth’s atmosphere meets space. While I am disappointed by the loss of investigative capabilities, I believe this process is a necessary step to preserve the research community’s ability to use Arecibo Observatory’s other assets and hopefully ensure that important work can continue at the facility,” emphasized Michael Wiltberger, head of NSF’s Geospace Section.