A new report from the National Academies of Sciences, Engineering, and Medicine analyzes the causes of the 2020 collapse of the National Science Foundation’s telescope at the Arecibo Observatory in Puerto Rico, where NSF maintained research operations for its National Astronomy and Ionosphere Center, and draws lessons learned for other unique, critical science facilities.

Long-term zinc creep-induced failure in the 57-year-old telescope’s cable spelter sockets was the root cause of the telescope’s collapse, the report says. Sockets filled with zinc held in place a set of cables suspending the telescope’s main platform over the reflector dish. Gradually the zinc lost its hold on the cables and allowed several of them to pull out, leading to the collapse of the platform into the reflector. 

The failure sequence began with Hurricane Maria, over three years prior to the collapse, according to the report. Indications of cable pullout were minimal before the hurricane. Large and progressive cable pullouts could be seen during post-hurricane visual inspections, observation of which should have prompted remedial action. Safety factor calculations made following the first cable failure did not recognize the accelerated time-dependent materials failure process governing the eventual zinc pull out. 

This is the first documented case of long-term zinc-induced creep failure despite a long history of usage over a century, the report notes.  A possible explanation for the accelerated zinc-creep is long-term low-current electroplasticity, induced by the electromagnetic waves from the Arecibo Telescope. It recommends that the NSF should offer the remaining socket and cable sections for study by the research community.

The committee that wrote the report reached its conclusions through extensive review of forensic investigations commissioned by the University of Central Florida and NSF, information gathering from employees at Arecibo Observatory, study of relevant research, consultations with other experts, and examination of structural analyses, engineering plans, inspection reports, photographs, and repair proposals.

More broadly, the report says that building and operating cutting-edge, custom-designed research facilities presents unique challenges, where prior designs and experience may not be a reliable guide, and unprecedented modes of failure can never be fully anticipated. But careful monitoring should be increased as facilities age to detect deterioration and potential novel failure modes, to the extent that is reasonable. NSF should make explicit funding provisions for detailed, ongoing condition maintenance and monitoring.

The report also contains other recommendations related to operations and maintenance manuals, inspection regimes, and independent audits.

DETAILS: Failure Analysis of the Arecibo Observatory 305-Meter Telescope Collapse is available for immediate release. Media inquiries should be directed to the Office of News and Public Information at tel. 202-334-2138 or email news@nas.edu.