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The large telescopic “ear” designed by Cornell in Arecibo, Puerto Rico, which listened to the illuminating crackle of the cosmos for nearly six decades, now hears silence.
In the wake of two recent support cable failures, the National Science Foundation (NSF) will dismantle and dismantle the giant dish of the Arecibo Observatory, the world-class radio telescope in Puerto Rico conceived by Cornell’s faculty, built with federal funding and then operated by Cornell for its first five decades.
The NSF announced the news on November 19.
“Arecibo has been an incredibly productive facility for nearly 60 years,” said Jonathan Lunine, professor of physical sciences David C. Duncan and chair of the Astronomy Department of the College of Arts and Sciences (A&S).
“For the Cornell scientists and engineers who took a daring dream and made it come true, for the scientists who made new discoveries with this extraordinarily powerful planetary radio telescope and radar,” Lunine said, “and for all the young people who were inspired to become scientists at the sight of this huge telescope in the center of the island of Puerto Rico, the end of Arecibo is an inestimable loss. “
In August, a support cable broke off and cut through the massive mesh dish, which measures 305 meters in diameter. The University of Central Florida, which now manages the facility on behalf of the NSF, has sent engineers to evaluate the repair of the famous telescope.
The engineers had formulated solutions and were ready to implement emergency structural stabilization to the cable system that holds the dish, according to NSF. But on November 6, pending delivery of replacement cables, a main cable broke.
Due to the stress on the second broken cable – which was thought to still be structurally sound – scientists at the NSF, which funds the facility, and engineers concluded that the remaining cables were likely weaker than originally believed.
Conceived in the late 1950s by the late William E. Gordon, Professor of Electrical Engineering Walter R. Reed, Arecibo was a radar / radio telescope designed to study the Earth’s upper atmosphere and near space.
The telescope was built in a natural basin in central Puerto Rico in the early 1960s and has become the world’s most powerful radio telescope and a key tool for astronomy, atmospheric science, and planetary science.
Like a gigantic ear attentive to the sky, the Arecibo telescope had been the largest single aperture radio telescope on Earth, tuned to find pulsars, galaxies and objects in the solar system and examine our planet’s ionosphere. It is so large that the height of the Empire State Building fits its diameter; the Washington Monument would sit comfortably at the focal point of the plate.
The Arecibo listened to natural noise throughout the universe day and night. In 2012, the observatory captured one of the most fleeting, mysterious and rare events in deep space, a so-called “fast radio burst” that lasted just three thousandths of a second.
“It was a single impulse,” said James Cordes, Cornell Professor of Astronomy (A&S) George Feldstein and a prolific and enthusiastic patron. “The nature of these explosions had been questioned … and the discovery at Arecibo cements the fact that they are astrophysical.”
Arecibo found the first pulsars in a binary system – a duet of neutron stars – in 1974, Cordes said. He mapped water ice deposits in craters at Mercury’s poles, discovered lake-like structures on the Saturnian moon Titan, and measured the precise orbits of asteroids near Earth.
The discovery of the two pulsars in a binary orbit led to confirmation of Albert Einstein’s prediction about the existence of gravitational waves, he said. This was the best proof of their existence, until LIGO directly detected gravitational waves in 2015.
“My first trip to Arecibo was in 1972 as a first-year graduate student at the University of California, San Diego, working on pulsars,” Cordes said. “Since then, I’ve made about 150 trips to Puerto Rico and spent a total of three years there.
“It was always a great thrill in the telescope control room,” Cordes said, “to see the pulses of rotating neutron stars – pulsars – displayed on an oscilloscope in real time.”
Forty-six years ago, Cornell astronomy professors Frank Drake and Carl Sagan famously sent a radio message via Arecibo to the skies – containing basic information about the human race – to potential extraterrestrials. The aim was to draw attention to the enormous power of the newly installed radar transmitter at the observatory.
“It was a strictly symbolic event, to show we could do it,” said Donald Campbell, now Professor Emeritus of Astronomy (A&S), who was an associate researcher at the observatory at the time.
Campbell went on to become director of the National Astronomy and Ionosphere Center, then based in Cornell, which managed the telescope until 2011 for the NSF.
Arecibo was also the primary solar system radar facility in the world, and was well-funded by NASA to enable precise studies of the orbital motion of near-Earth asteroids, according to Campbell. “This is a big loss to track them down,” he said.
“Arecibo could determine the size, shape and rotation of asteroids close to Earth and provide far more accurate predictions of their future orbits than those achievable using optical telescopes alone.”
Martha Haynes, Goldwin Smith’s Professor of Astronomy (A&S), first used Arecibo in 1973, when she was a summer research intern. He used Arecibo constantly. “Atomic hydrogen surveys using Arecibo,” he said, “have been the cornerstone of my research career.”
Haynes’s work at Arecibo led to the discovery of the filamentous nature of large-scale structure in the universe, which earned her the 1989 Henry Draper Medal of the National Academy of Sciences, an honor she shared with the emeritus professor of astronomy. Riccardo Giovanelli.
Currently, Cordes is part of a project called NANOGrav (the North American Nanohertz Observatory for Gravitational Waves), which uses pulsars as astrophysical clocks to detect gravitational waves from binary black holes.
“In 15 years of collecting data on this project, Arecibo has contributed half of it,” Cordes said. “We were on the verge of making our first takeover, so this is a particularly dire and important loss. Our NSF-funded project team is now considering how to address it.”
Related links
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