By Scott Hamilton

The National Science Foundation was forced to retire the Arecibo Observatory’s massive radio telescope dish following multiple issues with the cables suspending the dish. The announcement came on Nov. 19, 2020, after a second cable suspending the dish unexpectedly snapped.

In August 2020, one of the suspension cables slipped out of its socket, leaving the 900-ton science platform that is suspended over the dish with one less support. Engineers evaluated the situation in August and had plans to make repairs to the support structure. There were strong indications that the telescope could be safely and successfully repaired, until the unfortunate event on Nov. 19, that left the 900-ton platform precariously hanging in the balance.

The NSF requested and received reports from three separate engineering firms before making the decision that the facility was beyond repair, without putting repair staff at extreme risk, so the fate of the facility has been decided. The goal was to preserve the telescope without putting anyone’s safety at risk, stated Sean Jones, assistant director for the Mathematical and Physical Sciences Directorate. After reviewing the reports, it was decided that they must safely demolish the telescope or risk putting the rest of the facility at risk from an uncontrolled collapse of the damaged platform.

For more than 50-years, the Arecibo Observatory was the world’s largest single-aperture telescope, before being surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. The telescope was built using a natural sinkhole in Arecibo, Puerto Rico, to house the 305-meter spherical reflective dish. The 900-ton steerable radio receiver was suspended one-hundred-fifty meters above the surface of the dish and designed to be steerable with the use of multiple cables.

During its lifetime the telescope has been used to search for extra-terrestrial life, observe distant stars, planets, and galaxies, and is responsible for uncountable scientific discoveries. Because of the unique design of the telescope, it has been the filming location for several science-fiction films, including the climatic fight scene in the James Bond film, “GoldenEye.“ It was listed on the US Register of Historic Places in 2008.

The observatory was first damaged by Hurricane Maria in 2017 and later affected by earthquakes in 2019 and 2020. The last earthquake, in August of 2020, caused the first cable to slip from its anchor point. The shift in weight from the damage put extra strain on the second cable, leaving the telescope in an unusable and unrepairable state. It is a sad day for astronomers on a global level as an icon of the community is laid to rest. Until next week, stay safe and learn something new.

Scott Hamilton is a Senior Expert in Emerging Technologies at ATOS and can be reached with questions and comments via email to

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