The world-renowned radio telescope at the Arecibo Observatory in northern Puerto Rico, now on the brink of collapse, is set to be withdrawn from service, the National Science Foundation (NSF) announced today.
Each of the observatory's three towers has four primary cables that hold up a 900-ton equipment platform suspended above the telescope's massive reflector dish. In early August, an auxiliary cable slipped from its socket on Tower 4, carving a 100-foot-long gash into the dish.
And on Nov. 6, a main cable — also attached to Tower 4 – snapped. If another of Tower 4's cables ruptures, the platform might not hold and could collapse into the telescope's dish. Inspections of other cables revealed breaks and slippages as well.
Sean Jones, Director for the Mathematical and Physical Sciences Directorate at the NSF, said the telescope will be dismantled. The rest of the observatory will remain open.
Jones said the NSF's goal had initially been to preserve the telescope without putting people's safety at risk.
"However, after receiving ... the engineering assessments, we have found no path forward that would allow us to do so safely, and we know that a delay in decision-making leaves the entire facility at risk of an uncontrolled collapse, unnecessarily jeopardizing people and ... the additional facilities," Jones said.
NSF officials are hoping they can develop their decommissioning plan in time to avoid an uncontrolled collapse of the telescope, preserving the visitors' center and other nearby buildings. But they don't yet have a timeline for the process.
"Any information I'm giving you right now is pure speculation until that technical plan is developed [and] accepted by our engineering teams," Ralph Gaume, director of NSF's Division of Astronomical Sciences, said. "It's believed that that preparation of that technical execution plan will take a number of weeks. So it's going to be a while before we can tell you how long the development or ... the execution of that plan will take."
The observatory's rich 57-year history makes it a source of pride for Puerto Ricans and the global scientific community.
Arecibo has been a vital resource for radio astronomy, astrophysics, atmospheric studies and solar system astronomy.
In 1974, scientists used Arecibo to detect whirling pulsars — the first evidence for gravitational waves — earning them the 1993 Nobel Prize in Physics. Arecibo has also played an important role in the search for life beyond our planet, also known as the search for extraterrestrial intelligence (SETI). In the 1970s, it was used to beam a message about Earth and humanity into space.
The observatory has faced a number of hurdles over the decades. Hurricane Maria damaged it in 2017. This past January, a series of earthquakes rocked Puerto Rico and the Arecibo Observatory closed — only to be hit with the COVID-19 pandemic not long after.
The community at Arecibo is the observatory's true treasure, says Ashley Zauderer, program director at the observatory. She lauds Arecibo's workers for braving Hurricane Maria, frequent earthquakes over the years and the COVID quarantine to continue working there.
"There's an incredibly diverse and amazing group of scientists and dedicated staff and engineers at the observatory, and I mean, I think it is their passion to continue to explore, to learn, and that is the true heart and soul of Arecibo," she said.
Gaume says he believes in the ability of the global astrophysics community to cope with the loss of this telescope.
"The Arecibo 305-meter telescope had powerful, unique capabilities that made it especially valuable. That said, we're confident in the resilience of the astrophysics community, and the NSF will be encouraging other facilities that it funds to work directly with the Arecibo scientific community and investigators to provide them with appropriate support," he says.
Elie Levine is an intern on NPR's News Desk.