Faced with the collapse, the famous Arecibo Observatory will be demolished

Puerto Rico’s famed Arecibo Observatory, known for helping scientists peer into deep space and listen to distant radio waves, is set to be dismantled and demolished after engineers conclude the structure’s structure is at risk of collapse. While the teams attempt to salvage parts of the observatory, the decommissioning will put an end to the popular 57-year-old telescope, which has been featured in numerous films and television shows.

The decision comes after two major cables failed at the facility in recent months, causing significant damage to the observatory. The National Science Foundation (NSF), which oversees Arecibo, assessed the impact of cable breaks and found that the facility’s other cables may soon fail as well. If any of the remaining cables break, engineers fear the 900-ton platform suspended above the structure could crash into Arecibo’s iconic 1,000-foot-wide dish. It is also possible that three surrounding towers, more than 300 feet high, could tip over in any direction, potentially hitting the visitor center or other important buildings nearby.

With this imminent threat in mind, NSF has determined that Arecibo cannot be safely repaired without risking human life. The agency’s engineers evacuated the facility and set up a safety exclusion zone around spaces where people could be in danger in the event of a collapse. Meanwhile, engineers are now working on a plan on how to safely dismantle the structure, which could involve the use of helicopters and possibly even explosive demolitions. “This decision is not an easy one for NSF to make, but the safety of people is our number one priority,” said Sean Jones, assistant director of mathematics and physical sciences at NSF, during a call with reporters. .

The Arecibo Observatory has been a key part of the scientific community for the past half century, allowing scientists to observe exotic objects and events in deep space, such as pulsars and mysterious bursts of distant radio waves. Arecibo has also been a key tool in the search for asteroids orbiting near the Earth, helping astronomers find objects that could potentially pose a threat to the planet. In addition, Search for Extraterrestrial Intelligence (SETI) scientists used Arecibo to search the sky for deep space radio transmissions that could potentially come from intelligent worlds. Movie viewers will also recognize Arecibo from its inclusion in films such as Golden eye is Contact.

Image: UCF

The past few years have not been kind to Arecibo, though. In 2017, the facility sustained significant damage when Hurricane Maria passed over Puerto Rico, causing up to $ 14.3 million in required repairs. Then, in August of this year, an auxiliary cable, used to support the floating platform above the telescope, slipped out of its socket and fell, piercing the observatory’s giant dish. At the time, the University of Central Florida, which runs Arecibo, stopped observing the telescope and launched an investigation, promising to make repairs.

As engineers worked to obtain a replacement auxiliary cable, a second main cable snapped on November 6, also falling on the dish. The cable, which was attached to the same tower as the failed auxiliary cable, caused further damage to the structure and neighboring cables. NSF engineers made a full assessment of the structure after this second cable break and found that the remaining main cables, each weighing approximately 15,000 pounds, could not be relied upon. Arecibo’s main cables were installed decades ago, while auxiliary cables were installed in the 1990s. “All main cables, all decades old and traversed by storms, earthquakes and constant high humidity, may no longer be able to carry the load for which they were designed. [to carry]”Ashley Zauderer, program director of the Arecibo Observatory at NSF, said during the call. Indeed, the loss of a single extra cable on one of the surrounding towers could lead to the uncontrolled collapse of the entire observatory.

The engineers don’t have a time frame for when the collapse could happen, but they say the structure will fall apart soon if no action is taken and there isn’t much that can be done to prevent a collapse from occurring. “Attempts to stabilize or test the cables could also lead to accelerating the catastrophic failure,” Ralph Gaume, director of NSF’s division of astronomical sciences, said during the call. “The engineers cannot tell us the safety margin of the structure, but they warned us that the structure will collapse on its own in the near future.”

NSF admits that while the agency was focused on other auxiliary cables slipping out of their sockets, no one had expected the main cable to break, despite finding some evidence of weakening in the cable not working. After the cable failure in August, the engineering teams began more frequent monitoring of Arecibo and noted that 12 of the cable’s 160 wires had broken on the failed cable. However, the engineers thought the cable was strong enough to withstand these breaks and continue to hold. “It was identified as a problem that needed to be addressed,” Zauderer said. “It just wasn’t seen as an immediate threat and I don’t think anyone understood that the cable had clearly deteriorated.”

Ultimately, NSF plans to dismantle the 900-tonne platform and giant antenna in a controlled manner, even if the engineers don’t know exactly how long it will take or how much it will cost. And not all of Arecibo will be a total loss. NSF hopes to continue work on the Arecibo Observatory’s LIDAR facility eventually, as well as the visitor center. There is also an off-site facility on Culebra Island, which collects cloud and precipitation data. In the near future, the analysis and cataloging of the data collected by the Arecibo telescope will also continue.

While it is a sad day for NSF, the agency is adamant that this was the best decision for the people working at the observatory, and they are the most important assets. “I think it is easy to say that it is the telescope, but it is not the telescope that is the heart and soul [of the observatory], it’s the people, “Zauderer said.” NSF has really prioritized the safety of what’s really the treasure. “

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