Second cable break at the Arecibo telescope in Puerto Rico | Science

By Daniel CleryNov 9, 2020, 2:40 PM

The already damaged Arecibo Observatory was struck again on November 7 when one of its 12 main support cables broke and tore the main antenna of the radio telescope. The incident occurred barely 3 months after the failure of another cable. Researchers fear that increasing stress on the remaining cables could lead to cascading failures and the collapse of the antenna platform suspended above the antenna.

“It’s not a pretty picture,” says Joanna Rankin, radio astronomer at the University of Vermont. “It’s pretty damn serious.” It was “without a doubt” the worst observatory accident in its long history, says former principal Donald Campbell, now at Cornell University.

The nearly 60-year-old telescope, built in a depression in the hills of Puerto Rico, is still treasured by researchers. Its enormous 307-meter dish – the largest in the world until passed by China’s five-hundred-meter-aperture spherical radio telescope in 2016 – makes it very sensitive. And it’s one of the few telescopes that can not only receive radio waves but also emit them, in the form of radar beams, which helps researchers track nearby asteroids that could threaten Earth.

The observatory was damaged when Hurricane Maria devastated Puerto Rico in 2017. Repairs continued in August when a 13-centimeter-thick auxiliary cable, one of six suspended between three support towers and the suspended antenna platform, has come loose from its socket on the platform. Auxiliary cables were added in 1994 to deal with the additional weight of new antennas added in an upgrade. Last month, the University of Central Florida (UCF), which heads a consortium running the observatory, requested $ 10.5 million for emergency repairs from Arecibo owners, the National Science Foundation (NSF) .

The last cut – at 7:39 p.m. local time on a Friday night – was in one of the main 9-centimeter-thick support cables. Four of these cables connect each of the support towers to the 900 ton platform. The two faulty cables were attached to the same tower, so the remaining cables are under significant additional stress. “The forces are getting frightening,” says former Arecibo manager Robert Kerr.

NSF said in a statement: “We are monitoring the situation and examining all possible options to accelerate the stabilization of the structure. Our top priority is the health and safety of Arecibo staff. NSF handed over management of the observatory to the UCF-led consortium as part of the agency’s effort to cut spending on older facilities to help pay for new ones. NSF has yet to say whether it will pay for repairs UCF requested – or whatever additional costs incurred by the latest cable break. But Campbell says the general impression is that NSF has been “very supportive since the first cable break.”

Kerr says there were a lot of finger points and suggestions that managers didn’t follow up with with upkeep of the aging facility. The instruments added in 1994 created additional stresses for which the structure was not originally designed, he says. “There have been many steps to get us to where we are now,” he says.

Arecibo is essential for many areas, and it would be a “big loss” if it wasn’t fixable, Rankin says. “Its sensitivity is so much greater than any other instrument and it is so much more flexible,” she says. He has a spectacular range of abilities, Campbell says, with a view “from the stratosphere to the far reaches of the universe. It would be a great shame if this were lost.