January 15, 2021

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Work progresses to repair damage to the Arecibo Observatory

On August 10, an auxiliary cable broke and damaged the reflector plate and the Gregorian Dome.

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Arecibo – The Arecibo Observatory (AO), one of the largest and most powerful in the world, was disconnected on August 10 when an auxiliary cable broke and damaged the reflector plate and the Gregorian Dome.

While the cause of the incident has yet to be determined, AO’s leadership team continues to work closely with the National Science Foundation (NSF), which owns the facility, and Central Florida University, who manages NSF facilities under a cooperative agreement with Ana G. Méndez University and Yang Enterprises, Inc ,. It was reported in written statements on Tuesday.

“We continue to make progress, but the process is slow as we develop a comprehensive plan for facility repairs and prioritize the safety of our staff,” said Francisco Córdova, AO director.

“Our staff, as well as the external companies that have been hired, are working diligently to understand the cause of the failure and make plans on how we can return the telescope to normal operations as soon as possible,” added Córdova.

What has been done to date

A complete structural model has been developed for the Arecibo Observatory platform, towers and suspension cables.

The model has enabled a better understanding of the safety margins and capabilities of the existing structure and appropriate action on repair plans as the installation of temporary repairs and further evaluation progresses.

Cable buckling studies were completed for all auxiliary cables. These studies were necessary to calculate the real loads on the cables and to properly calibrate the structural model.

A comprehensive safety assessment plan has been developed, ensuring that quantifiable measures of structural integrity and capacity are captured before crews are allowed to perform temporary repair work in those areas.

The socket that was involved in the flaw was removed on September 28 and sent to Florida for a forensic evaluation at NASA Kennedy Space Center.

Experts from the center will conduct non-destructive testing and analysis in conjunction with the forensic engineering firm leading the investigation.

This work is expected to be completed by the end of October. The forensic investigation will also include the evaluation of the failed cable and ultimately the socket that is still connected to the platform.

During the past weeks they began the installation of an instrumentation system, which will continuously monitor the state of the structure.

This is necessary to help minimize the risk to personnel working on and near the structure.

Instrumentation includes strain gauges, tilt gauges, and will eventually include an acoustic measurement device.

All of this will allow the team to assess the state of the structure as it progresses.

NSF has completed the review of a temporary repair plan. An order has been placed for temporary friction clamps.

Friction clamps will be installed in two backstay cable locations and are intended to prevent cable loading as a precaution should these cables fail to fit.

These sockets were identified as problematic as the cable / socket spacings were observed to exceed acceptable thresholds.

A replacement auxiliary suspension cable has also been ordered and is expected to be in AO by mid-December, in addition to the corresponding pair, and two temporary cables to be used in the repair.

NSF has asked the observatory team to develop a supplemental proposal to cover the costs of these analyzes, immediate facility stabilization efforts, and completion of the assessment and engineering design for the repair necessary to return to operational status.

The AO team is working diligently on this, which includes a detailed project execution plan and a cost estimate for these repairs.

“In summary, we are making significant progress toward restoring the operational capacity of this historic facility,” Córdova said.

“We are very grateful for the continued support we have received from the AO community,” concluded the engineer.

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