Arial view of the collapsed telescope dish at the Arecibo Observatory in Puerto Rico.

The Arecibo Observatory’s 305-metre-wide telescope dish collapsed in late 2020, after some supporting cables had snapped.Credit: Ricardo Arduengo/AFP via Getty

After a world-famous radio telescope at the Arecibo Observatory in Puerto Rico collapsed two years ago, many scientists hoped that the US National Science Foundation (NSF), which runs the facility, would eventually build a new one to replace it. Instead, the agency has announced that it will establish an educational centre for science, technology, engineering and mathematics (STEM) at the site. The revised plan might wind down or drastically alter the remaining research being done at Arecibo.

“It’s heartbreaking,” says Héctor Arce, an astronomer at Yale University in New Haven, Connecticut, who is from Puerto Rico and has worked on Arecibo advocacy efforts. “To many, it seems like yet another unjust way of treating the colonial territory of Puerto Rico.”

The NSF says that it is following community recommendations in not rebuilding the large telescope and instead focusing on education. “We are not closing Arecibo,” says Sean Jones, head of the NSF’s Directorate of Mathematical and Physical Sciences. “We think this new approach and new centre will be catalytic in many areas.”

The agency announced its plans on 13 October in a call for proposals. It is asking for ideas on setting up and running an educational centre at Arecibo, at a cost between US$1 million and $3 million a year for five years, starting in 2023. That money might or might not include the funds needed to operate the research facilities at Arecibo that are still in use, such as a 12-metre radio antenna and a lidar system that uses lasers to study Earth’s atmosphere.

The situation “could be worse”, says Abel Méndez, an astrobiologist at the University of Puerto Rico at Arecibo. But “it could be much, much better”.

“It is devastating to know that that’s their ultimate decision,” says Desireé Cotto-Figueroa, an astronomer at the University of Puerto Rico at Humacao. “Especially despite all the efforts made by the staff and scientists of the Arecibo Observatory and by the general scientific community to keep it working as the research centre of excellence that it has always been with the observing facilities that are left.”

A powerhouse of education

One key question is how the Arecibo site will draw students and teachers if there is little active research to participate in. “Yet the NSF calls for proposals for a world-class educational institution,” says Anne Virkki, a planetary scientist at the University of Helsinki. “How does anyone do that without the world-class scientists, engineers and instruments?”

The NSF says that it is asking for precisely those kinds of idea. The new centre could support ongoing work in astronomy and planetary science, or it could focus on other areas of research, such as the biological sciences, says James L. Moore III, the head of the NSF’s education and human-resources directorate. “Here’s an opportunity to reimagine what the possibilities could be,” he says.

The Arecibo Observatory has long been a powerhouse of STEM education in Puerto Rico because of its renowned telescope and place in astronomical history. Students who trained there have gone on to become astronomers and planetary scientists in many countries.

The 305-metre-wide radio telescope that collapsed in 2020 had a key role in many scientific fields for more than half a century, including the search for extra-terrestrial life, the discovery of the first exoplanets and of gravitational waves, and the study of near-Earth asteroids and of fast radio bursts.

The NSF has run the observatory since the 1970s, working with a series of contractors. It has been trying to wind down investment in Arecibo since 2006, to shift funding to newer astronomical facilities. Advocates rallied and research continued, but the observatory faced fresh challenges in 2017, when Hurricane Maria damaged much of the facility, and in early 2020, when a series of earthquakes caused more damage.

Then came the collapse of the large dish. One of its crucial supporting cables had failed in August 2020, and after another snapped in November that year, the NSF decided that the telescope was too structurally unsound to repair. An engineering investigation revealed five factors that contributed to the collapse, including the design of the cable system, deferred maintenance and damage from hurricanes and earthquakes.

An observatory no more

Research has continued at the observatory’s smaller facilities. Currently funded projects using those instruments will be able to finish up, Jones says, and scientists can ask to continue their use under the scope of the educational centre.

The lidar facilities include a potassium laser that studies the temperature of the layers of Earth’s atmosphere and a planned new instrument to probe aerosols such as atmospheric dust. The 12-metre dish antenna is used for a range of research, including mapping the Sun for space-weather studies, and timing the spin rate of some rapidly revolving collapsed stars known as pulsars.

Many scientists who work with Arecibo instruments are now scrambling to work out how to wind down their research projects. Under the proposed plan, the site will no longer be called the Arecibo Observatory — becoming instead the Arecibo Center for STEM Education and Research.