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International Standard Book Number-13: 978-0-309-70222-5
International Standard Book Number-10: 0-309-70222-4
Digital Object Identifier: https://doi.org/10.17226/26982

Cover: Photo courtesy of the Arecibo Observatory, a facility of the National Science Foundation.

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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2024. Failure Analysis of the Arecibo Observatory 305-Meter Telescope Collapse. Washington, DC: The National Academies Press. https://doi.org/10.17226/26982.

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COMMITTEE ON ANALYSIS OF CAUSES OF FAILURE AND COLLAPSE OF THE 305-METER TELESCOPE AT THE ARECIBO OBSERVATORY

ROGER L. McCARTHY (NAE), McCarthy Engineering, Chair

RAMÓN L. CARRASQUILLO,¹ Carrasquillo Associates

DIANNE CHONG (NAE), Boeing Engineering, Operations & Technology (retired)

ROBERT B. GILBERT (NAE), The University of Texas at Austin

W. ALLEN MARR, JR. (NAE), Geocomp, Inc.

JOHN R. SCULLY, University of Virginia

SAWTEEN SEE, See Robertson Structural Engineers

HABIB TABATABAI, University of Wisconsin–Milwaukee

Study Staff

CAMERON OSKVIG, Board Director, Study Director

JAYDA WADE, Research Associate (until July 31, 2023)

JOSEPH PALMER, SR., Program Assistant

RADAKA LIGHTFOOT, Financial Business Partner (until March 20, 2023)

DONAVAN THOMAS, Financial Business Partner (from March 20, 2023)

BOARD ON INFRASTRUCTURE AND THE CONSTRUCTED ENVIRONMENT

JESUS M. DE LA GARZA, Clemson University, Chair

BURCU AKINCI, Carnegie Mellon University

STEPHEN AYERS, Ayers Group

BURCIN BECERIK-GERBER, University of Southern California

LEAH BROOKS, The George Washington University

MIKHAIL V. CHESTER, Arizona State University

JAMES (JACK) DEMPSEY, Asset Management Partnership, LLC

LEONARDO DUENAS-OSORIO, Rice University

DEVIN K. HARRIS, University of Virginia

DAVID J. HAUN, Haun Consulting, Inc.

CHRISTOPHER J. MOSSEY, Fermi National Accelerator Laboratory

ANDREW PERSILY, National Institute of Standards and Technology

ROBERT B. RAINES, Atkins Nuclear Secured

JAMES RISPOLI, North Carolina State University

DOROTHY ROBYN, Boston University

SHOSHANNA D. SAXE, University of Toronto

Staff

CAMERON OSKVIG, Board Director

JAMES MYSKA, Senior Program Officer

BRITTANY SEGUNDO, Program Officer

JOSEPH PALMER, SR., Senior Program Assistant

DONAVAN THOMAS, Finance Business Partner

Dedication

This report is dedicated to committee member Dr. Ramón L. Carrasquillo, who unexpectedly passed away before this report’s release. His pragmatic and insightful contributions strengthened the report. In addition to his extensive engineering and materials science expertise, his deep connection to Puerto Rico helped the committee develop a nuanced understanding of the community and culture surrounding the Arecibo Observatory. He is remembered by the committee as a thoughtful, warm, and generous colleague.

NOTE: Image courtesy of Carrasquillo Associates.

Reviewers

This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.

We thank the following individuals for their review of this report:

Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by WILLIAM F. BAKER, Skidmore Owings and Merrill, LLP, and STEVE BATTEL (NAE), Battel Engineering. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.

Contents

PREFACE

SUMMARY

1 INTRODUCTION

History of the Arecibo Telescope

Arecibo Telescope Cable System

Statement of Task

2 THE COLLAPSE: WHAT HAPPENED

Arecibo Telescope Failure Sequence

Hurricane Maria Hits the Arecibo Telescope

Post-Maria Arecibo Telescope Inspections

The Hurricane Maria Aftermath

Bureaucratic Delays in Funding Arecibo Telescope Hurricane Repairs

Sequence of Cable Failure Events

3 ANALYSIS

Cable Socket Zinc Creep Failure

Cable End Sockets

Wire Breaks

Earthquake

Wind Speed Consideration in the Arecibo Telescope’s Design

Governing Cable Design Standards

Arecibo Telescope Cable Load

Risk Considerations

Structural Robustness

Monitoring

4 ARECIBO TELESCOPE’S MANAGEMENT AND OVERSIGHT

5 OTHER LESSONS LEARNED

State of Knowledge

Continued Research

BIBLIOGRAPHY

APPENDIXES

A Committee Member Biographical Information

B Information-Gathering Activities

C Arecibo Telescope Cable Failure Mechanisms Considered by the Committee

D Arecibo Telescope Design Issues Considered by the Committee

E Acronyms and Abbreviations

Preface

It has been my privilege to chair this committee of distinguished subject-matter experts in its investigation and final probable cause determination of one of the most publicized and baffling failures of the modern era. It became clear shortly after the Arecibo Telescope’s collapse that the zinc used to anchor the steel supporting cable wires into their sockets had allowed the failed cables to slip out of their sockets, known as spelter sockets. The sockets slowly lost their grip on a critical number of the cable wires via slow zinc “creep,” a process where the zinc deformed slowly at a load below half the socket’s nominal strength. Although the committee agrees with the conclusions from other forensic reports regarding zinc creep at the connection being the failure mechanism, the baffling question was, “Why was there excessive zinc creep at such loading?” Such a failure had never been reported previously in over a century of widespread zinc spelter socket successful use.

Fortunately, the committee had the benefit of the detailed analysis and well-documented reports from NASA; Wiss, Janney, Elstner Associates, Inc.; and Thornton Tomasetti, Inc., without which it could not have completed its task. Building on their work, the committee presents a clear and plausible explanation of why the telescope’s sockets failed when no such sockets have ever been reported to have failed before. Unfortunately, there was not enough data available to prove our explanation. It is simply the most plausible hypothesis based on the data we do have.

Without the depth and breadth of expertise on the committee, its task would remain uncompleted. I think I speak for everyone on the committee when I say that none of us could have done this alone. I want to thank my colleagues for their unwavering dedication to the task. Their professionalism and competence made my job an enjoyable one.

Roger L. McCarthy, Chair
Committee on Analysis of Causes of Failure and Collapse of the 305-Meter Telescope at the Arecibo Observatory