Arecibo Observatory, a Great Eye on the Cosmos, Is Going Dark

One of the great icons of human curiosity, the Arecibo radio telescope, is going to be torn down, the National Science Foundation, its owner, announced today. From its perch in the mountains of Puerto Rico, the observatory has served for decades as the vanguard of the search for alien civilizations and guarded the planet against killer asteroids.

The telescope, with an antenna 1,000 feet across nestled in a sinkhole valley and a 900-ton constellation of girders and electronics hanging in the air above it, was long the largest single antenna in the world, a destination for astronomers as well as a location for Hollywood movies like “Contact.” Like the rest of the island commonwealth, it has been lashed and damaged by hurricanes in recent years and under financial duress, raising questions about the observatory’s future.

Trouble began on Aug. 10 when an auxiliary cable slipped out of its socket and gashed the antenna dish below. The University of Central Florida, which manages the observatory for the N.S.F. hired three different sets of engineers to assess the situation.

The observatory had already ordered a replacement and engineers were still trying to figure out what had happened and how to proceed when, on Nov. 6, one of the main cables that support the receiver platform snapped. Both of the cables that failed were attached to the same support tower and the engineers, according to Ralph Gaume, director of the astronomy division of the National Science Foundation, said that one more cable breakage from that tower would cause the whole telescope to collapse.

The engineers concluded that all the cables were suspect and might not be capable of carrying the loads they were designed to support. Any repair effort would only endanger workers and the rest of the observatory and would probably not prevent an “uncontrolled catastrophic collapse” in the words of Dr. Gaume during Thursday’s telephone news conference, at some time in the future.

The result, he said, was that the telescope could not be safely repaired. Dr. Gaume commended the observatory’s leadership in its work to assess whether the observatory could be saved.

“Until these assessments came in, our question was not if the observatory should be repaired but how,” he said. “But in the end, a preponderance of data showed that we simply could not do this safely. ”

ImageThe falling cable left a 100-foot gash in the telescope’s reflector dish.
Credit…Arecibo Observatory, via Associated Press

Kevin Ortiz Ceballos, a physics student and aspiring astronomer at the University of Puerto Rico, said in an email that it had always been his dream to work at Arecibo.

Now he said, “It feels like the rug has been pulled out from under us and our dreams to work in astronomy in Puerto Rico has vanished.”

The N.S.F. staff said they did not know how long the decommissioning would take or how much it would cost. Some facilities at the observatory would be preserved, they said, including a visitor center and a lidar, or laser radar, which is used to probe the atmosphere and ionosphere.

The loss to the world’s astronomers is devastating, and the internet filled with tributes and calls to “build it back better,” in the words of Denton Ebel of the American Museum of Natural History in New York. Many people with connections to the island and the observatory shared their memories and thoughts to a hashtag on Twitter called #WhatAreciboMeansToMe.

Ed Rivera-Valentín, a planetary scientist based in Houston, said that the hashtag showed that, “Arecibo’s value is much deeper than science, it is cultural.”

The place was also loved by visiting astronomers who came there to do research.

Jill Tarter, perhaps the world’s leading seeker of aliens, now retired from the SETI Institute in Mountain View, Calif., rhapsodized in an email about “the constant croaking of the coquis, the perfumes of the tropical forest,” as well as the jogging path underneath the dish ringed with orchids and Orion rising over the treetops. But she said the thing she missed most was “the staff and the resident scientists who were very close knit, offered us superb technical support, and threw wonderful parties with lots of dancing.”

Dan Wertheimer of the University of California, Berkeley, a leader in the search for extraterrestrial intelligence, wrote in an email, “Arecibo has made profound discoveries, helping Earthlings understand our planet and the universe.”

He added, “I hope Congress can help the Puerto Ricans in some other way.”

The Arecibo facility was originally built in 1963 and run by Cornell University under contract to the Air Force Research Laboratory, partly out of a desire to understand the properties of objects like nuclear warheads tumbling through the upper atmosphere. As a result, it was built to be both a telescope and a planetary radar, and many astronomers have used it to map dangerous asteroids as they buzzed past Earth.

For years, it hosted the largest single radio antenna on the planet, only surpassed in 2016 by a new telescope in China that is 1,600 feet in diameter.

One of its early feats, in 1967, was to discover that the planet Mercury rotates in 59 days, not 88 as astronomers had originally thought.

Over time, Arecibo became the flagship for the search for extraterrestrial intelligence, or SETI, the optimistic quest for radio signals from alien civilizations.

One of its directors was astronomer Frank Drake, then at Cornell, now retired from the University of California, Santa Cruz. He was famous for first pointing a radio telescope at another star for indications of friendly aliens, then for an equation, still in use today, that tries to predict how many of “them” are out there.

On Nov. 16, 1974, Dr. Drake beamed the equivalent of a 20-trillion-watt message toward M13, a cloud of about 300,000 stars some 25,000 light-years from Earth, as part of a celebration of an upgrade to the antenna.

The message consisted of 1,679 zeros and ones. Arranged in 73 rows and 23 columns, the bits formed pictures of a stick man, the radio telescope, a DNA helix, the solar system, the numbers 1 through 10 and more.

Before Dr. Drake sent it off, he tried out the message on his Cornell colleagues, including Carl Sagan, the author and proselytizer of the search for life in the cosmos. None of them could decode all of it. Maybe E.T. would be smarter when the signal finally reached somewhere, but the real point of such messages, Dr. Drake and Dr. Sagan always admitted, was to raise the consciousness of those of us back here on Earth and an awareness of our own status as cosmic travelers in an unknown and obviously weird universe.

In 1974, the same year that the first SETI message was sent, astronomers Joseph Taylor and Russell Hulse, both now at Princeton, used the Arecibo telescope to discover a pair of pulsars orbiting each other.

By timing the pulses over several years, the astronomers determined that the system was losing energy at the exact rate it would occur if the pulsars were radiating gravitational waves — the ripples in space-time that Einstein predicted to exist but which were not directly detected until 2016, by the LIGO gravitational wave observatories. In 1993 Dr. Taylor and Dr. Hulse won the Nobel Prize in Physics for their observation.

In 1990 a Polish astronomer, Aleksander Wolszczan, made another landmark discovery with Arecibo: PSR B1257+12, a pulsar with an irregular heartbeat. Further investigation revealed that the pulsar was orbited by three planets — the first planets ever discovered orbiting a star other than the sun. Today hundreds of such exoplanets are known, and their study is the fastest-growing field in astronomy.

The observatory also cemented a place in popular culture, with starring roles in movies like “Contact,” starring Jodie Foster, the James Bond film “Goldeneye” and episodes of the “X-Files” television show.

The future of Arecibo became precarious earlier this century. In 2007, the National Science Foundation, which has run the observatory since the early 1970s on an increasingly tight budget, said it might have to close if a partner could not be found to take on some of the financial load.

Since 2016, it has been managed by the University of Central Florida under a cooperative agreement with Universidad Ana G. Méndez and Yang Enterprises. The annual budget is about $12 million, including funds from NASA and the National Science Foundation, according to the University of Central Florida.

As Dr. Tarter said in her email, “it is very sad to witness the passing of this scientific Queen. She withstood powerful hurricanes, but age appears to have gotten the upper hand.”

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