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In August, a disconnected auxiliary cable tore the dish of the Arecibo Observatory. Last week, another cable failed.
OBSERVATORY OF ARECIBO
By Daniel Clery
The already battered Arecibo Observatory was hit by another hit on November 7 when one of its 12 main support cables snapped and ripped off the radio telescope’s main dish. The incident comes only 3 months after another cable fails. Researchers fear that increased stresses on the remaining cables could lead to cascade failures and the collapse of the antenna platform suspended over the dish.
“It’s not a pretty picture,” says Joanna Rankin, a radio astronomer at the University of Vermont. “This is damn serious.” It is “arguably” the worst accident at the observatory in its long history, says former director Donald Campbell, now at Cornell University.
The nearly 60-year-old telescope, built in a depression in the hills of Puerto Rico, is still prized by researchers. Its huge 307-meter dish, the largest in the world until it was surpassed by the Chinese Aperture Spherical radio telescope in 2016, makes it very sensitive. And it is one of the few telescopes with the ability not only to receive radio waves, but also to emit them, in the form of radar beams, which helps researchers track down nearby asteroids that could threaten Earth.
The observatory suffered damage when Hurricane Maria devastated Puerto Rico in 2017. Repairs were continuing in August when a 13-centimeter-thick auxiliary cable, one of six stretched between three support towers and the suspended antenna platform, became it is detached from its grip on the platform. Auxiliary cables were added in 1994 to cope with the extra weight of the new antennas added in an update. Last month, the University of Central Florida (UCF), which leads a consortium that operates the observatory, requested $ 10.5 million for emergency repairs from the owners of Arecibo, the National Science Foundation (NSF).
The last break – at 7:39 pm local time on Friday evening – was in one of the 9cm thick main support cables. Four of these cables run from each of the support towers to the 900-tonne platform. Both failed cables were connected to the same tower, so the remaining cables are subjected to significant additional stress. “The forces get frightening,” says former Arecibo director Robert Kerr.
NSF said in a statement: “We are monitoring the situation and considering all possible options to accelerate the stabilization of the facility. Our top priority is the health and safety of Arecibo personnel. “The NSF has transferred management of the observatory to the UCF-led consortium as part of an agency effort to reduce spending on older facilities to help pay for the new ones. NSF has not yet said whether it will pay for the repairs required by UCF or any additional costs incurred by the latest cable break. But Campbell says the overall impression is that NSF has been “very supportive ever since. from the first interruption of the cable “.
Kerr says there were a lot of tips and tricks that the managers hadn’t kept up with the maintenance of the aging facility. The tools added in 1994 created additional stresses that the structure was not originally designed for, he says. “There were a lot of steps to get to where we are now,” he says.
Arecibo is critical to many fields and would be a “big loss” if it wasn’t repairable, Rankin says. “Its sensitivity is much greater than any other tool and it is much more flexible,” he says. It has a spectacular range of capabilities, says Campbell, with a view “from the stratosphere to the edge of the universe. It would be a real shame if this were lost. “
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