The already battered Arecibo Observatory was hit with another blow on 7 November when one of its 12 main support cables snapped and tore through the radio telescope’s main dish. From a report: The incident comes just 3 months after the failure of another cable. Researchers are concerned that increasing stresses on remaining cables could lead to cascading failures and the collapse of the antenna platform that is 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 “without a doubt” the worst accident to befall the observatory in its long history, says former Director Donald Campbell, now at Cornell University. The nearly 60-year-old telescope, built into a depression in the hills of Puerto Rico, is still prized by researchers. Its huge 307-meter dish — the largest in the world until overtaken by China’s Five-hundred-meter Aperture Spherical radio Telescope in 2016 — makes it very sensitive. And it is one of just a few telescopes with the ability not just to 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 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 strung between three support towers and the suspended antenna platform, detached from its socket on the platform. The auxiliary cables were added in 1994 to cope with the extra weight of new antennas added in an upgrade. Last month, the University of Central Florida (UCF), which leads a consortium managing the observatory, applied for $10.5 million for emergency repairs from Arecibo’s owners, the National Science Foundation (NSF). The latest break — at 7:39 p.m. local time on a Friday evening — was in one of the 9-centimeter-thick main support cables. Four such cables run from each of the support towers to the 900-ton platform. Both failed cables were attached to the same tower, so the remaining cables are under significant extra stress. “The forces become scary,” says former Arecibo Director Robert Kerr.

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