The big dish at the Arecibo Observatory in Puerto Rico is on the verge of collapse, leaving officials with no choice but to retire the famous radio telescope. Astronomers around the world are now having to face a grim reality: that this dutiful dish—in service for the past 57 years—is no more.
I have to admit, the thought that the 1,000-foot (305-meter) dish at Arecibo would have to be torn down never occurred to me when I first started to cover this story during the summer. The first disturbing development came on August 10, when an auxiliary cable slipped out from its socket, crashing through the dish below. The falling cable created an unsightly 100-foot scar, but at the time, the incident seemed more of a nuisance than a catastrophic problem. And indeed, officials with the observatory soon made arrangements to repair the damage and replace the missing cable.
Things took a dramatic turn for the worse on November 6, when a main cable snapped and also fell onto the structure. This was the moment when I really started to worry. A missing auxiliary cable is one thing, but a missing auxiliary cable and a main cable? Not good. In my mind’s eye, I imagined the 900-ton platform, which is suspended 450 feet (137 meters) above the dish, being held together by string. A new image of a badly frayed cable didn’t ease my anxiety.
I reached out to the Arecibo Observatory, the National Science Foundation, and the University of Central Florida, which manages the facility on behalf of the NSF. On the morning of Thursday November 19, I woke up to an NSF email alerting me to a press conference that was to be held later the same morning. Finally, I thought, I would be able to report on pending repairs and a strategy for bringing the beleaguered facility back online. After registering for the press conference, however, the NSF sent me further details: The iconic dish was slated for demolition.
It felt like a punch to the stomach.
Engineering teams brought in to evaluate the situation said the platform could undergo a catastrophic collapse at any time, making it unsafe for workers. The dish, in operation since 1963, would have to undergo controlled disassembly in such a way to preserve other assets at Arecibo, including a LIDAR facility and visitor’s center.
While scientific work at the Arecibo Observatory will continue, the radio dish is done. And that’s a huge shame. In addition to its cultural importance, the dish fostered some excellent science, including the first detection of a binary pulsar (which earned the team a Nobel Prize in Physics), the first radar maps of Venus, the detection of potentially hazardous asteroids, the first exoplanets ever discovered, and insights into gravitational waves. The facility was also used to transmit a message to aliens, and of course, search for wayward radio signals sent by extraterrestrial intelligences.
Saddened by the retirement of the big dish, I reached out to scientists to get their thoughts on the news. One person I absolutely had to contact was Jill Tarter, an astronomer and SETI scientist. Tarter, as some of you might know, inspired Jodi Foster’s character in the 1997 film Contact (if you haven’t seen this film, now would be a good time to watch, as it features the Arecibo Observatory). Here’s what she had to say:
I’ve been going to Arecibo since 1978. Over the decades we’ve built a lot of Arecibo-specific hardware, written a lot of software, and bent the telescope control system into modes it was never designed for. Arecibo was an impressive feat of engineering, a scientific workhorse, and it never lost that aura of being slightly exotic, no matter how many times I visited there; the constant croaking of the coquis, the perfumes of the tropical forest, the local Ron del Barrilito, the Gregorian dome with its unmistakable compressor cadence, the jogging track underneath the dish ringed with small orchids, Orion rising over the treetops as seen from the balcony of the VSQ [lodging rooms for visiting scientists], before heading off to my midnight shift of Project Phoenix [a search for extraterrestrial intelligence] observations, and the absolutely best view on the island from atop the platform. But most of all, I remember the staff and the resident scientists who were very close knit, offered us superb technical support, and threw wonderful parties with lots of dancing.
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.
Hurricanes, yes, but also earthquakes.
I wrote to Avi Loeb, a science professor at Harvard University and the longest-serving chair of its astronomy department. He replied:
As it turns out, I visited Arecibo with my family and gave a seminar there in summer 2016. We had a special tour of the facility where we were told that, thanks to a numerical mistake related to the initial purpose of the observatory, the design ended up with a 305-meter telescope, the largest radio telescope for many decades. It took a decade or so to get the calibration right and bring the dish to its full operational capability.
The NSF decision to decommission Arecibo implies a big loss to radio astronomy. The astronomy community in the U.S. should come up with a new plan on how to maintain our leadership in radio astronomy. Without Arecibo, the biggest radio dish on Earth is the Chinese Tianyan telescope (FAST), which is 500 meters in diameter.
Anne Virkki, a radar scientist at the Arecibo Observatory, described how the loss of the telescope will affect both science and Puerto Rico:
The Arecibo Observatory has 57 years of scientific discoveries in different scientific branches (astronomy, planetary science, and space and atmospheric sciences), including one that resulted in a Nobel Prize in physics. Right before the first cable fell, we observed an asteroid called 2020 NK1 that had a relatively high impact probability, and that observation allowed NASA to determine that it doesn’t pose a risk after all. The observatory has helped hundreds, if not thousands of students in different stages of their academic paths and inspired millions just by existing. For everyone who has worked there, it has left a feeling of having been part of something big. While the telescope’s support cables are compromised, it is not scientifically obsolete nor a replaceable instrument by the other existing radio telescopes of the world. And it will leave an immense hole in all Puerto Ricans, their national pride, education opportunities, and, in some cases, their wallets, as it has actively contributed to the Puerto Rican (already degrading) economy for decades.
Virkki also shared her thoughts as a private citizen, not as a representative of the Arecibo Observatory, an employee of UCF, or any other affiliated companies or agencies:
This is a much bigger loss than any of the federal funding agencies dare to admit. The Goldstone Solar System Radar will not be able to take over what Arecibo Observatory could be doing. To me personally, it feels more like a home than a workplace, and the NSF’s decision to demolish it feels like some big company wanting to demolish the home where you grew up to build a highway on top. Demolishing it was never the only option.
As a relevant aside, Virkki was planning to use the Arecibo dish to study Apophis, a potentially dangerous asteroid that will be making a somewhat close approach to Earth next year and an exceptionally close approach in 2029. That’s not going to happen now, but other radio observatories will be ready.
Andrew Siemion, an astrophysicist and director of the Berkeley SETI Research Center, shared his thoughts as well:
It is difficult to overstate the role that Arecibo has had on SETI research—being a singular asset in multiple major SETI observing campaigns, including Project Phoenix, the Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations (SERENDIP) and SETI@Home, acting as the vehicle for multiple interstellar messaging activities, including the Arecibo Message, and serving as the canonical reference point for the detectability of terrestrial communication systems through its planetary radar. Alongside Arecibo’s strength as a research instrument, it has also had a tremendous impact on the popular conception of SETI, including countless appearances in documentaries, books, and movies, including Contact. Arecibo has also nurtured the radio astronomy community during its nearly six-decade career, serving as the training ground for hundreds of radio astronomy students. It is worth pointing out that some professional observatories are fairly conservative when it comes to allowing students to work directly on instrumentation, but Arecibo always had a welcoming and collaborative attitude towards students or anyone else with a “crazy idea.” This overall philosophy was a huge part of its success, and its meaning to the SETI community.
Of all the radio telescopes I have ever visited, and I have visited a few, Arecibo stands apart as a magically surreal symbol of human ingenuity and exploration. The journey to the telescope, winding through narrow jungle roads and then happening on to the gate and access road is strange enough. But the drive up to the control building, during which the telescope remains hidden from view, and then the walk into the observer’s console where huge windows open up to a panorama of this incredible structure ensconced in the foliage is just... indescribable. I think I am most sad for the many future students, explorers… humans, that will not get the chance to make that incredible journey.
Victoria Kaspi, at astrophysicist at McGill University in Montreal who studies pulsars (rapidly spinning stars that shoot beams of electromagnetic radiation from their magnetic poles), said she’s still in “disbelief” about the whole situation:
Arecibo has been absolutely crucial to pulsar astrophysics over the past 40+ years. Already Nobel-celebrated for the discovery of the first binary pulsar, and its subsequent landmark test of Einstein’s theory of General Relativity, Arecibo has done so much more for our understanding of the galactic pulsar population. My colleagues, students, and I have used it to discover hundreds of pulsars in the past decade, including recently the most relativistic binary pulsar system yet known, totally unexpected sources like eccentric binary millisecond pulsars, and a system that helps understand puzzles raised by gravitational wave sources detected by aLIGO [advanced Laser Interferometer Gravitational-Wave Observatory]. In fact, just days before the NSF decommissioning announcement, my PhD student Emilie Parent discovered a whole bunch of new pulsars in our Arecibo data! Even until its last operational moments, Arecibo was still a phenomenal and unique discovery machine, which is what makes this turn of events so frustrating.
During the press conference on November 19, I asked NSF officials if they’re committed to building a new radar dish at Arecibo—one possibly even better than the original. Understandably, they couldn’t commit at this time, as the priority now is to safely decommission the dish. One thing they made clear, however, is that they’re not abandoning the Arecibo Observatory altogether and that we can expect some exciting science in the years to come.
My hope now is that scientists, students, and anyone else with an interest in radio astronomy will work together to make this happen: to see a new dish installed at Arecibo. Let’s turn this setback into an opportunity—this story ain’t over yet.