800-Tonne Platform Threatens to Crush Famed Arecibo Observatory Dish

800-Tonne Platform Threatens to Crush Famed Arecibo Observatory Dish
That cable doesn't look so good. This drone photo of the Arecibo Observatory was taken after November 6, when a main cable snapped and fell onto the receiving dish below. (Image: UCF Today)

The Arecibo Observatory in Puerto Rico is in an exceptionally precarious state following the recent failure of two support cables, placing the future of this renowned facility in doubt.

As we feared, the situation at Arecibo appears to be dire. With two support cables gone, the 816 tonne platform located directly above the dish is now being supported by the remaining main and auxiliary cables — some of which are already fraying, according to the University of Central Florida (UCF).

The trouble began on August 10, when an auxiliary cable fell onto the dish, causing extensive damage. A main cable subsequently snapped on November 6, which served to make the situation even worse. A safety zone has been set up around the damaged reflector dish, and the only personnel allowed at the facility are those attending to the crisis. Engineers from three different engineering firms are currently assessing the damage and trying to devise potential solutions. The UCF manages Arecibo for the National Science Foundation (NSF), in a cooperative agreement that involves Universidad Ana G. Méndez and Yang Enterprises.

Built in the early 1960s, the beloved observatory is starting to show its age. The facility is used by scientists around the world for a wide range of tasks, from atmospheric, stellar, and planetary science through to searches for aliens and potentially hazardous asteroids. Arecibo, as one of the most recognisable observatories in the world, was featured in the 1995 spy film GoldenEye and the 1997 sci-fi film Contact, in which Jodi Foster portrayed a SETI scientist. The observatory has a frustrating history, however, having to endure earthquakes, hurricanes, and fiscal uncertainties.

The engineers currently working at Arecibo are still trying to determine the cause of the recent cable failures and assess the observatory’s condition, which they’re doing with aerial drones and remote cameras. As UCF Today reports, the facility is designed such that the main cable should’ve been able to handle the extra load after the collapse of the auxiliary cable, but it did not. A preliminary analysis suggests the second cable failed because “it has degraded over time and has been carrying extra load since August,” according to UCF Today. The engineers will learn more once the failed main cable is analysed.

Troublingly, all of the remaining cables are now “supporting more weight than before, increasing the likelihood of another cable failure, which would likely result in the collapse of the entire structure,” notes the UCF report. What’s more, some of these cables are exhibiting wire breaks, pointing to the seriousness of the situation. As UCF Today points out, the engineering firms “cannot verify the integrity of the other cables at this time.”

Mike Nolan, a research professor from the Lunar and Planetary Laboratory at the University of Arizona, said the situation at Arecibo is quite serious.

“The original cable failure in August was apparently a hidden manufacturing defect that was probably — my guess — triggered by the recent series of earthquakes in Puerto Rico,” he explained in an email. “Now that a second cable has failed, apparently due to overstress, we are all very concerned. There are six cables from that tower to the suspended structure: If two more fail on that same tower, the suspended structure definitely falls.”

Priority now is to take some of the tension off the remaining cables, Nolan said, “either by reducing the load or adding reinforcement,” or a combination of the two, “so that the problem of the manufacturing defect can be addressed.”

Officials with the observatory are trying to expedite receipt of two new support cables currently on order, and they’ve asked the NSF for financial assistance to help with temporary repairs.

Estimates from observatory officials place the current cost of the damage at $US12 ($16) million, reports the AP.

The NSF has “ensured that Arecibo Observatory has all funds needed for emergency repairs, engineering and forensic evaluation since the first cable failure,” explained NSF spokesperson Rob Margetta in an email. The NSF, he said, has “authorised Arecibo to take all reasonable steps and use allowable funds to secure the needed analysis and equipment,” and the NSF “is currently waiting on engineering analysis and cost estimates.” When asked if there’s a future for Arecibo, Margetta said the engineering and cost estimates are still ongoing and that the NSF won’t be able to answer this question until they’re complete.

In an email, NASA spokesperson Joshua Handal said the damage to Arecibo is still being assessed by the observatory management at UCF, after which the NSF “will consult with stakeholders, including NASA, to determine how to proceed.”

The future of the Arecibo Observatory, it’s fair to say, is now a big question mark. And that’s a real shame, given its scientific importance.

“The Arecibo Observatory is not the biggest radio telescope in the world, but it is still the biggest and most powerful radar. Most radio telescopes can only receive radio signals, but Arecibo can also transmit, as radars do,” Abel Méndez, associate professor of physics and astrobiology from the Planetary Habitability Lab at the University of Puerto Rico-Arecibo, said in an email. “Therefore, Arecibo is the best instrument in the world to study the properties and trajectory of any potentially hazardous asteroid moving toward Earth.”

During a recently concluded workshop to explore the various ways we could investigate the potentially hazardous Apophis asteroid when it passes Earth in 2029, Arecibo research scientist Anne Virkki expressed her concerns about the facility not being available any time soon. She had been planning to do radio scans of the asteroid in March 2021, when Apophis will come to within 10.5 million miles (16.9 million km) of Earth. Indeed, this now seems unlikely given the current situation. It’s a real loss, as scientists need to study this asteroid to the greatest extent possible.

Nolan, Méndez, Virkki, and so many other research scientists will now have to wait and hold their collective breaths in hopes that the situation at Arecibo won’t get worse than it is now and that it can soon be remedied.