NSF says it’s too early to decide whether to replace Arecibo


WASHINGTON — Two days after its dramatic collapse, National Science Foundation officials said it is too soon to determine whether the giant radio telescope at Arecibo Observatory will be, or should be, replaced.

The 305-meter radio telescope, for decades the largest in the world, collapsed early Dec. 1 when a series of cables supporting a 900-ton observing platform snapped. The platform crashed into the dish below, and the tops of the three towers that anchored the cables also broke off. No one was injured.

The collapse took place less than two weeks after the NSF announced it planned a “controlled decommissioning” of the nearly 60-year-old telescope. The agency decided not to attempt repairs to the telescope after cables broke in August and early November because engineering firms concluded that it would be unsafe for crews to perform the repair work.

At a Dec. 3 media briefing, NSF officials released video of the collapse. One video, taken by Carlos Perez from the observatory’s control room, shows the platform falling into the side of the dish. A second video, shot by Adrian Bague using a drone, captures the failure of cables at one of the towers.

“I want to express how deeply saddened we are here at NSF by the situation, and NSF is very thankful that no one was hurt,” said Ralph Gaume, director of NSF’s Division of Astronomical Sciences, during the briefing.

Ashley Zauderer, program director for Arecibo Observatory at the NSF, said that the agency established safety zones to restrict access around parts of the observatory at the recommendation of an engineering firm after a second cable broke in November. No one was in those restricted zones at the time of the collapse and all the most hazardous debris fell in those zones, she said.

The immediate focus of the NSF and the consortium that operates Arecibo for the agency is cleaning up the debris. “We’re still in the assessment process,” Gaume said, a process looking at both the damage and environmental impacts that should be completed by the end of the week. “It’s too early to say exactly what that cleanup looks like. We’re still in the assessment, but we’ll know soon.”

A longer-term issue is the future of the giant radio telescope. NSF officials reiterated that the overall Arecibo Observatory will not close, with operations of a 12-meter dish, a lidar for atmospheric observations and a visitor’s center remaining open. NSF will also provide the full funding it had planned to allocate to the observatory for fiscal year 2021.

“We recognize the significance of this loss to Puerto Rico, and the significance of this loss to so many who have called the Arecibo Observatory home,” said Zauderer.

Before the collapse, some lobbied to save the telescope. Resident Commissioner Jenniffer González-Colón (R-P.R.), Puerto Rico’s representative in Congress, sent a letter to House and Senate appropriators Nov. 20 asking them to appropriate funding “necessary to enable NSF to continue exploring options to safely stabilize the structure and maintain the telescope and surrounding areas.” The letter was also signed by Reps. Stephanie Murphy (D-Fla.) and Darren Soto (D-Fla.)

With repair no longer an option, the debate now turns to whether the radio telescope should be rebuilt. At the briefing, NSF’s Gaume said it was too soon to evaluate if the telescope will be rebuilt.

“With regards to replacement, NSF has a very well-defined process for funding and constructing large-scale infrastructure, including telescopes,” he said. “It’s a multi-year process that involves congressional appropriations and the assessment and needs of the scientific community. So, it’s very early for us to comment on the replacement.”

One aspect of that scientific assessment is the astrophysics decadal survey. The latest survey, dubbed Astro2020, is ongoing, and expected to be completed in the spring of 2021. Gaume didn’t comment on any impacts the collapse of Arecibo will have on Astro2020. Rob Margetta, an NSF spokesman, said after the briefing that NSF notified the Astro2020 steering committee of the collapse but has not made any requests for the committee to evaluate the impact of the loss of the telescope.

NASA, which has funded a part of Arecibo’s operations to use the telescope as a planetary radar, doesn’t expect to play a major role in any decision to rebuild the telescope. “This is an NSF facility. It has never been a NASA facility,” Thomas Zurbuchen, NASA associate administrator for science, said at a Dec. 1 meeting of the NASA Advisory Council’s science committee.

He noted that NASA has kept in close contact with NSF about the telescope. “We will follow the NSF’s lead in whatever they’re doing,” he said.