The famed Arecibo Observatory in Puerto Rico collapsed due to a combination of rotten zinc in the telescope’s cable jacks and previous damage from Hurricane Maria, according to a report released by the National Academies of Sciences, Engineering, and Medicine.
The massive radio telescope accident in December 2020 marked the end of a prolific source of radio astronomy data. According to a recent report, the root cause of the telescope’s destruction was “an unprecedented and accelerated long-term failure caused by zinc creep.” This failure occurred in the telescope’s cable slots, which are critical infrastructure elements to support the telescope’s 900-ton platform that hung above the radio antenna.
The cables had begun to fail even before the collapse. The NSF decided to demolish the dish before it fell, but the weakened infrastructure beat them to it. The Academy’s committee to analyze the causes of the failure and fall of the 305-meter telescope at the Arecibo Observatory has published a report with the corresponding title. The committee analyzed data and research collected and conducted by the University of Central Florida and the National Science Foundation (NSF).
The telescope’s fall in 2020 was dramatic and rapid. The cables suspending the telescope’s platform above its 1,000-foot (304.8-meter) antenna snapped, causing the platform to fall down through the radio antenna. The catastrophic fall took less than 10 seconds, ending 57 years of operation at the revered observatory in northern Puerto Rico. The observatory had discovered new exoplanets, created maps of other worlds, observed fast radio bursts, and helped humanity in its search for life beyond Earth.
“The lack of documented concern from the contracted engineers about the lack of cable pulling or safety factors between Hurricane Maria in 2017 and the accident is troubling.”
However, the report notes that the collapse began long before the fateful day in December 2020. The committee concluded that the “sequence of destruction” lasted 39 months and began with the aftermath of Hurricane Maria in September 2017. According to the report, inspections conducted after the hurricane found signs of cable slippage, but no one investigated or responded to them further. “The absence of documented concerns from contractor engineers about the lack of cable pulling or safety factors between Hurricane Maria in 2017 and the accident is troubling,” the committee writes.
But that’s not all. As the committee noted, “in the more than a century of successful use of the Arecibo telescope prior to its fall, all forensic examinations agreed that no such failure of the spelter slot had ever been recorded.” The report continued: “The only hypothesis the committee was able to develop that provides a plausible but unprovable answer… is that the creep of zinc in the sockets was unexpectedly accelerated under the uniquely powerful electromagnetic radiation of the Arecibo telescope.” In other words, the role of the sockets in suspending such a powerful radio transmitter somehow contributed to the 2020 disaster.
In October 2022, the National Science Foundation announced that the facility would be transformed into a STEM-focused educational center, scheduled to open in 2023. However, in June 2023, the observatory officially curtailed its succession plans. In September 2023, NSF announced its institutional partners who will lead the process of transforming the observatory into an educational center. The observatory may never collect radio data again, but it will continue its legacy as an epicenter of astronomical discovery in one form or another.
