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The long goodbye begins for iconic radio dish

The radio telescope at Puerto Rico’s Arecibo Observatory is on its way to extinction after 57 years of sparking dreams of alien contact — and after a grim three years of weathering nature’s blows.

Two of the cables supporting the telescope’s 900-ton instrument platform have slipped loose, ripping through the 1,000-foot-wide web of aluminum panels and steel cables that’s spread 450 feet below.

Engineers assessed the damage and determined that the risk of a catastrophic failure was too great to attempt repairs. If more cables snap, the entire platform could crash down, potentially causing the dish’s collapse and life-threatening injuries to workers.

“Although it saddens us to make this recommendation, we believe the structure should be demolished in a controlled way as soon as pragmatically possible, ” Thornton Tomasetti, the engineering firm that made the structural assessment, said in its recommendations to the National Science Foundation and the University of Central Florida, which manages operations at Arecibo on the NSF’s behalf.

“It is therefore our recommendation to expeditiously plan for decommissioning of the observatory and execute a controlled demolition of the telescope,” the firm said.

After consulting with other engineering firms and the U.S. Army Corps of Engineers, NSF decided to go ahead with the decommissioning.

“NSF prioritizes the safety of workers, Arecibo Observatory’s staff and visitors, which makes this decision necessary, although unfortunate,” NSF Director Sethuraman Panchanathan said in a statement.

Although the proximate cause of the damage was the structural failure of the two cables — on Aug. 10 and Nov. 6 — natural disasters have been particularly unkind to Arecibo in recent years. The telescope took a buffeting from Hurricane Maria in 2007, a string of earthquakes over the past winter and Tropical Storm Isaias in August. It’s conceivable that those blows could have contributed to the structural failures.

Over the past half-century, Arecibo has taken on more than its share of starring roles in radio astronomy. It had been considered the world’s largest single-dish radio telescope until China’s 1,600-foot-wide observatory — the Five-Hundred-Meter Aperture Spherical Radio Telescope, or FAST — took the title in 2016.

Arecibo has played a part in unraveling the cosmic mysteries surrounding exoplanets, near-Earth asteroids, black holes, gravitational waves, pulsars and fast radio bursts. But the observatory is best-known for its role in the search for extraterrestrial intelligence, or SETI.

In 1974, astronomers at Arecibo sent out the most powerful radio signals intentionally aimed at aliens — a coded broadcast known as the Arecibo Message. The observatory also served as a base for SETI listening sessions including Serendip and Project Phoenix.

Arecibo had Hollywood-style brushes with stardom in the movie “Contact,” starring Jodie Foster as an astronomer looking for alien signals; and in “GoldenEye,” a James Bond movie that staged a climactic scene at Arecibo’s instrument platform.

I had my own brush with Arecibo back in 2003, during a quick visit arranged by NSF. “If E.T. ever were to pay a visit to Arecibo, even the aliens might be impressed,” I wrote at the time.

NSF says it has already authorized a high-resolution photographic survey of the telescope site, which is nestled in a sinkhole amid Puerto Rico’s karst mountains. The results of that survey will be factored into the plan for decommissioning and disassembling the telescope.

If all goes according to plan, the Arecibo Observatory would continue to host a lidar research facility, the visitor center and an off-site facility that analyzes cloud cover and precipitation data. The University of Central Florida has been working with Microsoft Azure to archive Arecibo’s science data in the cloud — and NSF says the observatory’s on-site data will be migrated to servers outside the affected area. A detailed timetable for the process hasn’t yet been announced.

Although Arecibo’s radio telescope has gone dark, SETI fans can take solace in the fact that other radio astronomy facilities are going strong.

The $100 million Breakthrough Listen campaign is giving a boost to the Green Bank Telescope in West Virginia, the Parkes Telescope in Australia and the MeerKAT radio telescope array in South Africa.

Meanwhile, the SETI Institute has the Allen Telescope Array in California (which does SETI as well as other types of radio observations). And this year, the institute forged a partnership with the National Radio Astronomy Observatory for use of the Jansky Very Large Array in New Mexico (which is where Jodie Foster’s character ended up detecting aliens in “Contact.”)

Within the next decade, a monster radio astronomy project known as the Square Kilometer Array, or SKA, is due to take shape in Australia and South Africa. SKA aims to knit together thousands of networked antennas to provide an observational capability equivalent to a single radio dish that’s more than a kilometer (3,280 feet) wide. That’d be twice as wide as China’s FAST antenna.

Losing Arecibo is a heavy blow to Puerto Ricans, who have pointed to the radio telescope as one of their top scientific attractions.

“As an astronomer, this upset me. As a Puerto Rican, this actually broke my heart,” University of Maryland graduate student Giannina Guzman Caloca wrote on Twitter. “I cried on the way to class. I don’t think people understand the sense of pride and inspiration that Arecibo brought to many Puerto Ricans, especially those who grew up wanting to become astronomers.”

NSF’s Panchanathan vowed to preserve the scientific ties with Puerto Rico. “For nearly six decades, the Arecibo Observatory has served as a beacon for breakthrough science and what a partnership with a community can look like,” he said. “While this is a profound change, we will be looking for ways to assist the scientific community and maintain that strong relationship with the people of Puerto Rico.”

That’d be a good thing, and not just for us earthlings: If extraterrestrials ever do respond to the Arecibo Message, we need to make sure the reply gets to the right address.

By Alan Boyle

Mastermind of Cosmic Log, contributing editor at GeekWire, author of "The Case for Pluto: How a Little Planet Made a Big Difference," president of the Council for the Advancement of Science Writing. Check out "About Alan Boyle" for more fun facts.

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