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A broken cable irreparably damaged the dish
ARECIBO OBSERVATORY was designed in the era of space age monumentalism, an imposition of geometry on geology as striking in its simplicity and scale as the larger Brutalist architecture. When the James Bond franchise, in its pomp a showcase for iconic 1960s design, finally began using the 306-meter antenna as a location in the 1990s, the only surprise was that it had taken so long.
The observatory was not new in the field of espionage. It was created as a tool for using radar to study the ionosphere, an electrically charged upper layer of the atmosphere. The US Department of Defense was interested in this work, which could lead to new ways of characterizing incoming missiles or snooping enemy transmissions, which allowed it to earn money.
A standing dish large enough for the job would not have been practical. The designers therefore looked for a hole in the ground to reuse. They found it in northwestern Puerto Rico, a sinkhole where the limestone landscape had collapsed the right way. They built three towers on the edge of the abyss and hoisted the instrument’s electronic heart – the bit that emits and receives radio waves – into the empty space between them. Signals moving to or from this equipment would bounce off eight acres of wire mesh stretched below.
As a radar, Arecibo used the world’s largest parabola to study not only the ionosphere, but also the surfaces of nearby planets and passing asteroids. But it was as a radio telescope that he really excelled, making crucial discoveries during the 1960s and 1970s, the heyday of radio astronomy. The most famous were a pair of pulsars – spinning neutron stars – orbiting each other in a way that turned out to prove Einstein’s general theory of relativity. Later data revealed planets around another pulsar. It was the first definitive detection of planets beyond the solar system.
Arecibo has also been used for the capricious branch of radio astronomy, the search for extraterrestrial intelligence. Since 1960, radio astronomers have sometimes used their instruments to search for artificial signals from stars. In 1974, after an upgrade that saw the original mesh replaced with a parabola made up of 38,778 aluminum panels, Arecibo was used to go further. It transmitted a 1679-bit message to a star cluster 25,000 light years away. This post contains graphic representations of basic biochemistry and astronomy, as well as the technology with which it was sent.
Over time, technological advancements have eroded the advantages of Arecibo’s sheer size and its funding has declined. Engineering has started to show its age. In August, one of the cables supporting the instrument platform broke, damaging the dish. The snap of a second in early November seemed to portend an impending collapse. And so it must be closed.
But as the vegetation beneath the dish rises through its remains and the site falls into picturesque crumbling, the sketch of its cross section encoded in that 1970s post will continue. It is already 46 light years from Earth. Its pixels are now the farthest memorial of human achievement anywhere in the universe. And they always will.
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