Without the Arecibo telescope, our search for intelligent life is hamstrung

It’s the end of an era and we’re all a little poorer for it.


Structural engineers and repair crews have done all that they can but the end result is as we feared: the Arecibo radio telescope has to come down. The venerable space observatory has been out of commission since August when a cable atop Tower 4, which supports the platform, snapped and gutted a 100-foot long section from the telescope’s reflecting dish. At the time, the University of Florida, which runs the facility on behalf of the National Science Foundation, deployed three different engineering teams to investigate the problem.

That damage alone was enough to knock the observatory offline for months, however a second cable front the same tower subsequently snapped in November, further damaging the array and putting it in danger of an uncontrolled collapse. The situation has grown so dangerous that the National Science Foundation had serious doubts as to whether it could be repaired without putting lives in danger during the repair process.

“The telescope is in danger of catastrophic failure,” the NSF wrote in a November statement. “Any attempts at repairs could put workers in potentially life-threatening danger.” As such, the NSF announced on Thursday that it will be dismantling the array before it can come crashing down on its own.

“Until these assessments came in, our question was not if the observatory should be repaired but how,” Ralph Gaume, director of the astronomy division of the National Science Foundation, told the New York Times on Thursday. “But in the end, a preponderance of data showed that we simply could not do this safely.” It’s the end of an astronomical era and we’re all a little poorer for it.

In 1959, Cornell University contracted with ARPA to manage a gargantuan new radio telescope being built in the karst foothills, just outside Arecibo, Puerto Rico. The next year, crews broke ground as Cornell astronomer William E. Gordon oversaw the design and construction of the telescope, officially known as the National Astronomy and Ionosphere Center (NAIC). Stewardship of the site transferred in 2018 to the University of Central Florida, Yang Enterprises and UMET.

Completed in 1963, the Arecibo telescope was initially tasked with studying the ionosphere, one of Gordon’s specialties. However the reasoning behind the telescope’s construction actually grew out of an ARPA defense program which sought to create an early detection system for incoming nuclear missiles by spotting the atmospheric ionization generated by the high-speed friction of their flight. At the time, we didn’t have a very solid understanding of the Earth’s upper atmosphere, hence the need for an NAIC. The telescope was also clandestinely used to snoop for Soviet radar sites by detecting signals bounced off the moon.

The Arecibo telescope was simply massive. Its primary collection dish measures more than a 1,000 meters in diameter and is covered in nearly 39,000 individual aluminum plates. With a total collection area of 73,000 square meters (roughly 20 square acres), the NAIC stood as the largest single aperture telescope on the planet from the date of its completion in 1963 to 2016 when China completed its FAST telescope. The cables that snapped were two of 18 running between a trio of concrete support towers used to support a 900-ton receiver suspended nearly 500 feet above the surface of the dish.

Its gigantic footprint allowed the Arecibo telescope capabilities that smaller sites simply could not match. As such, competition to use the facility was brutal, necessitating an impartial three-person panel to assign observing time for only the most promising research. Even with the strict admittance policies, roughly 200 scientists visited the telescope each year.

It was used in a wide array of scientific studies -- observing everything from the Earth’s upper atmosphere and the heliophysics of the sun to distant fast radio bursts and pulsar emissions. In fact, the first exoplanets ever found were discovered orbiting a pulsar, PSR 1257+12, using the Arecibo telescope. What’s more, the Arecibo was behind the first detection of gravitational waves created by pulsars. That discovery wound up winning a Nobel in 1993. The telescope has also provided an invaluable aid in the search for extraterrestrial life.

The first attempt came on November 16th, 1974 with what is today known as the Arecibo Message. As part of a celebration marking the telescope’s recent remodeling, researchers from SETI blasted a radio signal -- “the most powerful broadcast ever deliberately beamed into space,” according to DARPA -- towards the M13 globular star cluster. It delivered a seven-part message devised by Cornell astronomer Frank Drake (as in Drake’s Equation) and Carl Sagan. We have yet to hear back. The Arecibo telescope also generated the data that the SETI@home project chewed through while the similar Edison@Home program discovered nearly two dozen new pulsars within the Arecibo’s reams of data.

The telescope had experienced a number of difficulties in recent decades including damage from Hurricane Maria in 2017 and unreliable funding. Still, the NSF’s decision has come as a gut punch to the scientific community. “Think about what the Golden Gate Bridge means to San Francisco, what the Statue of Liberty means to New Yorkers. Arecibo is this and more to Puerto Rico because it has gone beyond an icon,” Edgard Rivera-Valentín of the Lunar and Planetary Institute wrote to National Geographic. “For some of us, it became that goal to reach towards, that symbol that we can achieve great things, that pride that in our own backyard; we were serving the entire planet.”

Others, such as planetary scientist Ed Rivera-Valentín, have responded to the news with fond memories of their experiences there:

Still others took a more pragmatic view of the situation. “I'd say that the Arecibo closing is bad for SETI, but not disastrous,” Dr. Christopher Conselice, Professor of Extragalactic Astronomy at the University of Manchester, told Engadget. “It is a very sensitive telescope for searching for signals but is not the only game in town anymore.”

“For example, the $100M Breakthrough Listening project uses other telescopes, including Jodrell Bank in the UK and the Allen array, but does not use Arecibo,” he continued. “However, as we don't know if, how, or where a SETI signal would appear, the loss of Arecibo could potentially mean we do miss out on a detection.”

While it will cease operations, the facility will not be demolished. Instead, only the 305 meter tall telescope will be coming down and that process has already started. The NSF is also employing a fleet of HD camera drones to conduct photographic surveys of the area. There’s no timetable yet for when the decommissioning will be completed.

"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,” NSF Director Sethuraman Panchanathan said in a statement Thursday. “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."

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