Early on Dec. 1, 2020, 800 tons of steel collapsed into a yawning, forest-fringed concrete bowl once featured in a James Bond movie. But it took no fevered gunfire between Pierce Brosnan and Sean Bean to bring down what had once been the world’s largest single-dish radio observatory. Instead, the 1,000-foot-wide (305-metre) dish of the Arecibo Telescope owed its sad demise to the steady and inexorable creep of old age.
Carved six decades ago from a natural sinkhole to guard against unwanted terrestrial radio emissions, Arecibo’s shattered remains occupy the karst limestone foothills of Puerto Rico’s north coast, some 50 miles (80 kilometers) west of the bustling capital San Juan. Karst sinkholes, noted Arecibo’s founding father and first director, Cornell University physicist William Gordon, provided a perfect cavity to seat such an ambitiously large antenna dish.
The Arecibo site lies in a natural concave sinkhole nestled in the karst mountains ...
