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ARECIBO OBSERVATORY it was conceived in an era of space age monumentalism, an imposition of geometry on geology that strikes in its simplicity and scale as the greatest brutalist architecture. When the James Bond franchise, in its glitz a showcase for iconic 1960s design, finally managed to use the 306-meter dish as a location in the 1990s, the only surprise was that it took so a long time.
The observatory was not new to spycraft. 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 had an interest in this work, which could have led to new ways of characterizing incoming missiles or poking into enemy transmissions, so they amassed some money.
A freestanding plate large enough for the job would have been impractical. The designers then looked for a hole in the ground to reuse. They found it in northwestern Puerto Rico, a sinkhole where the limestone landscape had collapsed in the right way. They built three towers on the edge of the sinkhole and hoisted the instrument’s electronic heart – the bite that emits and receives radio waves – into the empty space between them. Signals traveling to or from this equipment would bounce off eight acres of stretched wire mesh beneath it.
As a radar, Arecibo used the largest dish in the world to study not only the ionosphere, but also the surfaces of nearby planets and passing asteroids. But it was like a radio telescope that really excelled, making some crucial discoveries during the 1960s and 1970s, the golden age of radio astronomy. The most famous was a pair of pulsars – rotating neutron stars – orbiting one another in a way that proved to prove Einstein’s theory of general relativity. Subsequent data revealed planets around another pulsar. This was the first definitive detection of planets beyond the solar system.
Arecibo has also been used for the capricious offshoot of radio astronomy, the search for extraterrestrial intelligence. Since the 1960s, radio astronomers have occasionally used their instruments to search for artificial signals from the stars. In 1974, after an upgrade that saw the original mesh replaced by a dish made up of 38,778 aluminum panels, Arecibo was used to take it one step further. It sent a 1,679-bit message to a star cluster 25,000 light-years away. Encoded in this message were graphical representations of basic biochemistry and astronomy and the technology with which it was sent.
Over time, technological progress has eroded the advantages of Arecibo’s size and its funding has diminished. Engineering has begun to show its age. In August one of the cables supporting the instrument platform broke, damaging the dish. The snapshot of a second in early November seemed to portend an impending collapse. And so it must be closed.
But as the vegetation beneath the plate rises through its remains and the site falls into a picturesque ruin, the sketch of its cross section encoded in that 1970s message will continue on its way. It is already 46 light years from Earth. Its pixels now form the furthest memorial to a human conquest anywhere in the universe. And they always will.■
This article appeared in the Science and Technology section of the print edition with the title “Si monumentum requiris respicite”
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