Collapse of world-renowned radio telescope leaves astronomical legacy

Syra Ortiz-Blanes
Miami Herald/TNS

SAN JUAN, Puerto Rico - The Arecibo Observatory was born in the mid-20th century from a confluence of earthly and celestial forces: William E. Gordon, the scientist who devised the massive radio telescope, wanted to study the Earth's upper atmosphere. The federal defense agency that funded its construction aspired to dominate the technology race against the Soviet Union.

And so, between 1960 and 1963, in an era brimming with the idea of space exploration and Cold War tensions, a radio telescope of power and size never before seen was built in Arecibo, a coastal town in northern Puerto Rico.

The grand project was matched by its equally grand home: a massive natural sinkhole, nestled in the forested limestone hills called mogotes, of the island's Karst Country. The location meant less excavation was needed. Its closeness to the equator - Puerto Rico is only about 1,200 miles north of the 0 latitude - offered a clear field of the planets overhead. Throughout the years, the radio telescope's capabilities were expanded to permit a deeper exploration of the cosmos.

And throughout its life, the radio telescope was a tool for many major achievements: from choosing a landing spot for the Apollo 11 mission to the discovery of the first planets outside our solar system.

The natural basin cupped the telescope's 1,000-foot diameter, grayish-white reflector plate. Above the stationary dish, three towers suspended a 900-ton, rotating platform. It housed receivers, transmitters, and other equipment within a dome that hung like half a golf ball in the air. The massive aluminum bowl captured the radio waves and focused them on the platform; its hardware translated the "sounds" of the universe into data and information for the scientists who study the universe's mysteries.

The radio telescope had survived hurricanes and earthquakes. But the National Science Foundation, the observatory's owner since the 1970s, in mid-November abruptly announced it would demolish the telescope. The instrument had become unstable in recent months as cables and wires failed and snapped. The federal agency had deemed repairs risky to people, and that there was no way to ensure long-term structural soundness. Following the announcement, a rallying cry to maintain the beloved Arecibo institution exploded on the island and around the world.

But before any machines could bring the telescope down, the platform and the dome plummeted into the reflective dish in the early morning of Dec. 1. Households across Puerto Rico woke up to somber and teary news anchors who confirmed what was treated as a national tragedy. The sinkhole, once a cradle of cosmic revelations, became a graveyard of metal and cement. A cloud of brown dust rose among the verdant mogotes as it crashed, visible from nearby homes. One former observatory scientist who lives nearby said it sounded like an "avalanche" or a "train."

During its 57 years in operation, the Arecibo Observatory has been a point of pride and a springboard of professional opportunities for Puerto Ricans, as well as a global icon of culture and achievement. The telescope was so well known it was featured in several movies, such as the 1995 James Bond flick GoldenEye and the 1997 sci-fi film Contact. Its sudden collapse left the instrument irreparably damaged, and its destruction has had significant consequences.

For Puerto Rican scientists and students, it's the loss of an institution that provided world-class education and work in a place lacking science, technology, engineering and mathematics opportunities. The observatory also shaped some of the brightest minds at home while luring others from across the globe - from India, Brazil, Canada and more - to the island.

For science, the collapse translates to lost knowledge: The aging telescope produced invaluable data around the clock for scientists across disciplines and countries. Every moment the instrument cannot be used is an opportunity lost, perhaps forever. The universe operates on a different timeline than humans. Windows of study can be as narrow as once in a lifetime - or multiple lifetimes.

"It's as if you had a baseball player, and you take away their glove, the ball and the bat," said Luisa Zambrano, a planetary scientist who has worked at Arecibo for seven years.

As for humanity, the telescope's demise could pose an existential threat. Arecibo's Observatory was a top-of-its-class tool for planetary defense. The instrument surveyed the characteristics and behaviors of near-Earth asteroids such as the monstrous Apophis, over 1,100 feet wide. The instrument's demise did not leave scientists flying blind, but it gave Earth asteroid myopia.

"We are going to significantly decrease our ability to provide safety to the planet in terms of possible asteroids that come nearby," said Zambrano.

Scientists, advocates of human advancement, and lovers of Arecibo are mourning. But the cries of those who asked the NSF to reverse its decision to demolish the radio telescope - before the instrument did the job itself - have not turned silent after its collapse. Instead, they have ignited into a chorus of voices demanding that the observatory be rebuilt and that the new one have the same or better capacities. Across the world, those whose lives have been touched by the observatory are organizing, so the mogotes may one day house a telescope that honors the first.

Zambrano is one of many people - scientists and members of the general public alike - advocating for a new instrument.

"It was difficult to go through the process of grief, but like in every mourning, you need to recuperate," she said. "The observatory's legacy has been so large that the only possible option we see is to reconstruct."


For almost six decades, the Observatory has been instrumental in some of the most important discoveries across a variety of scientific disciplines.

"What makes the telescope and scientific facility different from any other is the breadth of research that it does," said Dr. Robert Kerr, an astronomer and atmospheric scientist who served as observatory director. "It's made Nobel quality contributions to [radar and radio] astronomy, to atmospheric science, to planetary science."

Among Arecibo's earliest discoveries was determining that Mercury's rotation was 59 days, a month shorter than previously thought. A NASA historian confirmed to the Miami Herald that Arecibo's lunar radar maps were used to determine a landing spot for the Apollo 11 mission, the first human landing on the moon. The radio telescope's observations also assisted the space agency to choose where to land robotic probes on Mars for the Viking program in the 1970s.

The radio telescope both received and sent radio waves, making it unique among its peers in operation. It was used to broadcast the "Arecibo Message" in November 1974, a deliberate interstellar beam directed at a globular star cluster 25,000 light-years away. If properly decoded, it rendered among other things the numbers 1 through 10, images of the Arecibo Observatory, a map of Earth and the solar system and a human stick figure.

That "first use of the new radar transmitter" was part of a ceremony celebrating major improvements to the radio telescope, according to a 1975 paper authored by the Arecibo staff. The staff believed an alien response was unlikely, but it was as much a message to extraterrestrials as a testament to the instrument's capacities. The observatory eventually became a steady source of information for groups, organizations and scholars involved in the search for life beyond our planet.

The Arecibo Observatory has also been a place for many scientific firsts.

In 1974, physicists Russell Hulse and Joseph Taylor - who later won the Nobel Prize in Physics - discovered the first binary pulsar, a duo of neutron stars, massive stars that exploded and emit vast amounts of electromagnetic radiation. It was a finding that verified predictions from Albert Einstein's theory of general relativity.

In 1981, the radio telescope generated the first radar maps of Venus' surface, which had previously been difficult to do because of the thick Venusian clouds that cover the planet.

In January 1992, astronomers Aleksander Wolszczsan and Dale Frail published that they had found the first exoplanets outside our Solar System, rotating around a pulsar.  That would prove to be a momentous year for the Observatory in more ways than one: It was then that Arecibo detected deposits of ice on the polar regions of Mercury. Twenty years later, the NASA Messenger spacecraft confirmed frozen water in the shadowy, frigid craters of Mercury's poles.

"Every night and every day, people were discovering things," mused Kerr. "It was a very exciting place to work."

Kerr not only spent his work hours at the observatory: During his two stints as director, one between 2007 and 2008 and another from 2011 to 2015, he cumulatively lived there for five years, a modern-day Merlin in his tower.

"You never knew when you came downstairs what people had found the night before," said Kerr.

The former program director described the discoveries and findings of the telescope with awe. But more than anything, Kerr underscored the wondrous collegiality and community Arecibo fostered. Asteroids were subjects of fascination for some scientists, while others delved into the possibility of life on faraway planets. Some researchers spent their careers looking for exoplanets, while others used space like a cosmic laboratory to test gravitational laws.

But from the first hand who maneuvered the radio telescope in the 1960s to the last person who scouted the sky in August, when operations were suspended, an unbreakable bond formed among those who searched space from Arecibo.

Over 350 people use the observatory each year. Visiting scientists would impart knowledge during conferences and workshops at the premises. Kerr described meals with scholars from all over the world, who shared their discoveries and experiences. His favorite memory was his farewell lunch when he left the directorship for the first time. He still owns the beautiful prints from a local painter the observatory staff gave him.

"The love was amazing," said Kerr.


The Arecibo Observatory is located in Barrio Esperanza, a neighborhood named after the Spanish word for hope. Time and time again, that's what it offered to Puerto Ricans.

The island has experienced political unrest, economic instability, massive migration and devastating disasters in recent years. In 2020, even before the coronavirus pandemic swept the world, thousands of earthquakes convulsed Puerto Rico. They continue as the deadly pandemic rages.

But through it all - the despair, the death, and the decay - the Arecibo Observatory has embodied the search for what was beyond the visible eye, beyond the current possibility. That the telescope bore witness to the cosmos from the island, insulated by its natural geography, was a paradox. This small, Caribbean archipelago connected all of humanity to the universe above. For many Puerto Ricans, that was a truth they could depend on, no matter what tragedy struck next.

After Hurricane Maria in 2017, the radio telescope endured some damage. Still, it stood tall and proud, and the observatory doubled as a relief center. It provided water and power to nearby areas. Some staff stayed there following the storm, and the Federal Emergency Management Agency used the facility's heliport to deliver essential supplies.

"This was much more than just a scientific observatory," said Kerr.

The observatory has been a source of work and education. It employs over 100 professionals and attracts almost 100,000 visitors a year to north-central Puerto Rico. Many visitors are young children and teenagers enrolled in the island's schools. A field trip to the facility, whether with teachers or family, is a tradition of childhood.

For some, like Tamara González Acevedo, who first visited as a child with parents and relatives, the observatory persuaded them to become scientists.

"I think that is where I learned the word astronomer, because at least since I was in sixth grade, I have said I want to be an astronomer,' said González, 24. "The observatory gave me vocabulary, that knowledge of what science is, of what astronomy is, of what space is."

Many of the observatory's initiatives are geared towards building educational opportunities and engaging the public. Students even had the chance to use the radio telescope themselves. That kind of educational access to world-caliber tools and resources is unusual, and part of the institutional culture.

In 2013 and 2014, González was a member of the Arecibo Observatory Space Academy, a program for pre-college students to connect with scientists and learn to research. As a first-generation college student from the mountain town of Lares, "getting these kinds of opportunities was a challenge," she said.

Today, she studies physics at the University of Puerto Rico, and aspires to obtain a doctorate in the field. She hoped to work full-time in the observatory one day. Family members have reached out to her in solidarity with the loss.

"They might not know much, perhaps about the science behind the observatory and all the fascinating things that are done there. But they are very sad," she said. "I think that for them, it was a cultural symbol. It has become something that is part of Puerto Ricans."

For many students, the telescope's fall has forced them to rethink future plans and consider opportunities outside the island. But for children who never went on their first visit, losing the instrument is a loss of what could be, of the spark that ignites their journey into science.


The NSF told the Miami Herald that it plans to keep the Arecibo Observatory open, as well as some facilities and instruments in use. Still, there is no word from the federal agency on whether they will rebuild the radio telescope.

"NSF's process for funding telescopes and other large-scale infrastructure is an established procedure that involves congressional appropriations, work with stakeholders, and assessing the needs of the scientific community," the NSF statement said.

Estimates of how much replacing the radio telescope could cost vary. Dr. Kerr placed the number at around $200 million, reckoning it would be less expensive than a "medium-scale mission at NASA." But other scientists have put the figure at closer to $400 million.

Members of the public and the scientific community alike have raised questions about how the NSF handled decisions during the telescope's last months.

In a press conference on Dec. 3, the Director of NSF's Astronomy Division, Ralph Gaume, said that the University of Central Florida, which manages the observatory, had "all necessary funds" to engage in repair and stabilization efforts following the first auxiliary cable snap in August.

"Replacements for the auxiliary cable that fell in August had been scheduled for delivery," said Gaume. "And when the main cable broke on Nov. 6, NSF authorized expedited delivery of temporary cables."

But current observatory director Francisco Córdova told the Associated Press he believed there were other options, "such as relieving tension in certain cables or using helicopters to help redistribute weight." Others in Puerto Rico's scientific community agreed.

The NSF said it wasn't possible to work at any other speed or take another course of action.

"There was no way to perform all necessary actions required for a complete repair safely. Options such as relieving the cables' tension were actively pursued but included high-risk activities that had to be carefully planned," the federal agency told the Herald.

Regardless of the reason or inevitability of collapse, there is widespread consensus among observatory staff and the island's scientific community that a new radio telescope must spring up. Coalitions of scientists and the general public are quickly mobilizing to action and raising awareness of Arecibo's importance.

Within days, observatory employees had met with Gov. Wanda Vázquez to discuss the next steps. Dozens of users of the observatory, from today and times past, have gotten together in "vigils" over Zoom to both reminisce about the radio telescope and discuss possible actions to raise awareness. CienciaPR, an organization of Puerto Rican scientists with over 13,000 members, has also been mobilizing.

"This is an effort that will require a lot of money and time," said Mónica Feliú-Mójer, communications head for CienciaPR. "There must be a sustained effort of advocacy and public pressure." The Puerto Rican scientist said it was like a "dagger to the heart" to "see that icon fall."

There is also strong momentum and activism among young scientists. González is one of the leaders of the Save the Arecibo Observatory initiative, a student-led movement of over 160 individuals from Puerto Rican and mainland schools. The collective launched a petition to secure the needed funds from Congress to build a new radio telescope.

The overwhelmingly supportive response has left Arecibo Observatory employees and people affiliated with the institution feeling optimistic. They also think that once again, like in the 1960s, geopolitical factors - such as competition between the U.S. and China - could be possible motivators for the federal government to fund a new radio telescope. Until 2016, Arecibo was the world's largest filled-aperture telescope in the world, until China's FAST dethroned it. The same week as the collapse, news reports surfaced that China had become the second country to plant its flag on the moon.

Professor Abel Méndez, Planetary Habitability Lab Director, told the Herald that as many as 100 scientists across the world are writing a white paper to propose an "Arecibo 2.0" radio telescope, and what it could do to advance science.

"All of these facilities weren't born out of nothing. They were born with a white paper that presented the case of why we need this instrument," said Méndez.

For over 50 years, the radio telescope was a mighty ear and mouth for the Earth in space, sending and receiving radio waves, which became data, which became scientific knowledge, that explained the universe we inhabit in invaluable ways.

Today the radio telescope sits in pieces, deafened and silent, at the bottom of its sinkhole home.

But there are thousands of people across the world - such as Méndez, González, Kerr, Feliú-Mójer and Zambrano - speaking up for the radio telescope, and advocating for its successor.

"Now it's our turn to be the voice of the radio telescope, so we can have it once more," said Méndez.

So one day, Arecibo can hear the universe again, and the universe can in turn listen when Arecibo speaks.

This aerial view shows the damage at the Arecibo Observatory after one of the main cables holding the receiver broke in Arecibo, Puerto Rico, on Dec. 1, 2020. The radio telescope in Puerto Rico, which once starred in a James Bond film, collapsed when its 900-ton receiver platform fell 450 feet (140 meters) and smashed onto the radio dish below.