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STORY WRITTEN FOR CBS NEWS AND USED WITH PERMISSION
After weathering hurricanes and earthquakes, playing a central role in films like “GoldenEye” and “Contact”, Puerto Rico’s famous Arecibo Observatory, once the world’s largest radio telescope, will be demolished due to power outages. cables that left its huge sensing platform too unstable to attempt repairs.
“After looking at the technical evaluation, we couldn’t find any way forward that would allow us to do this safely,” said Sean Jones, deputy director of the mathematical and physical sciences branch at the National Science Foundation.
“We know that a delay in decision making puts the entire facility at risk of uncontrolled collapse, unnecessarily endangering people and additional facilities.”
Operated by the NSF through the University of Central Florida, the iconic observatory consists of a 1,000-foot-wide fixed satellite dish embedded in a bowl-shaped depression that reflects radio waves or radar beams onto a platform. 900 ton instrument form suspended 450 feet above by cables extending from three support towers.
For 57 years, the observatory has played a leading role in observing deep space targets, solar system bodies and, using powerful lasers, the composition and behavior of high terrestrial atmosphere.
But the beginning of the end came on August 10 when an auxiliary cable installed in the 1990s disengaged from its socket on a support tower and smashed into the dish below, tearing a gash of 100. feet long.
Engineers were making repair plans when one of the main 3-inch-wide cables attached to the same tower unexpectedly broke on November 6, causing the platform to tilt instrument and exerted additional tension on the remaining cables.
Analysis showed that the cable failed in calm weather at about 60% of its minimum breaking strength. Inspections of other cables showed fresh wire breaks and slips in several auxiliary cable outlets that were added to the structure in the 1990s.
An engineering firm hired by the University of Central Florida to assess the structure concluded that it would not be safe to proceed with the repairs. Even stress tests to determine the strength of the remaining cables could trigger a catastrophic collapse.
Instead, engineers recommended a controlled demolition, lowering the suspended instrument platform in such a way as to avoid damaging other structures on the periphery of the dish by ensuring that the towers themselves do not. collapse and ensuring that no cables whip into these structures.
“The telescope is at serious risk of an unexpected and uncontrolled collapse,” said Ralph Gaume, director of the Astronomical Sciences Division at NSF. “According to a technical assessment, even an attempt to stabilize or test the table could accelerate the catastrophic failure.
“The engineers cannot tell us the safety margin of the structure, but they have informed NSF that the structure will collapse on its own in the near future.
Plans to take down the platform of instruments have not yet been finalized and it is not yet known whether explosives will be used in a controlled demolition or whether it would be possible to lower in some way or further the platform to the dish below.
Either way, the 1,000-foot-wide telescope will essentially be destroyed. If the laser facility and visitor center will hopefully be preserved, but the radio telescope itself will not be.
“For 57 years this facility served as a resource for radio astronomy, solar system radar astronomy, space and atmospheric science,” said Gaume. “The 305-meter Arecibo telescope had powerful and unique capabilities, particularly valuable advantages.
“That said, we are confident in the resilience of the astrophysical community and that the NSF will encourage other facilities to work directly with the scientific community and Arecibo researchers to provide them with appropriate support now.”
Completed in 1963, the Arecibo Observatory was the largest single-dish radio telescope in the world until the China Five Hundred Meter Aperture Spherical Telescope, or FAST, began operations in 2016.
The satellite dish, made up of nearly 40,000 aluminum panels, was built in a depression left by a chasm. While the dish itself only moves with the Earth’s rotation, the instrument’s platform has a movable receiving paddle that allows astronomers to “look” at targets up to 40 degrees away. the vertical axis of the telescope.
With half a century of astronomical observations, the observatory has been featured in films ranging from the James Bond thriller “GoldenEye” to “Contact,” based on Carl Sagan’s novel about First Contact with Aliens.
The observatory also played a role in the search for extraterrestrial intelligence, or SETI. In 1974, the dish was used to convey a raw message into deep space. More recently, the observatory provided data used by the SETI @ home project, which searched for signals using the computing power of thousands of online personal computers.
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