Arecibo Observatory collapses ahead of planned demolition

The instrument platform of the 305-meter telescope at Arecibo Observatory in Puerto Rico collapsed overnight, according to the National Science Foundation.

It’s a final blow to one of the most powerful telescopes on Earth that has aided astronomical discoveries for 57 years and withstood hurricanes, earthquakes and tropical storms.

Engineers assessed the damage and determined that all three of the telescope’s support towers broke off, sending the 900-ton instrument platform plummeting down to the dish below. The telescope’s support cables also dropped. The observatory’s learning center was significantly damaged by the falling cables as well.

The collapse occurred just weeks after NSF announced that the telescope would be decommissioned and disassembled through a controlled demolition after sustaining irreparable damage earlier this year.

“The instrument platform of the 305m telescope at Arecibo Observatory in Puerto Rico fell overnight. No injuries were reported. NSF is working with stakeholders to assess the situation. Our top priority is maintaining safety. NSF will release more details when they are confirmed,” according to a tweet by the National Science Foundation.

“NSF is saddened by this development. As we move forward, we will be looking for ways to assist the scientific community and maintain our strong relationship with the people of Puerto Rico,” the foundation said in another tweet.

The spherical radio/radar telescope includes a radio dish 1,000 feet across and a 900-ton instrument platform suspended 450 feet above it. Cables connected to three towers hold the telescope in place.

“We are saddened by this situation but thankful that no one was hurt,” said NSF Director Sethuraman Panchanathan in a statement. “When engineers advised NSF that the structure was unstable and presented a danger to work teams and Arecibo staff, we took their warnings seriously and continued to emphasize the importance of safety for everyone involved. Our focus is now on assessing the damage, finding ways to restore operations at other parts of the observatory, and working to continue supporting the scientific community, and the people of Puerto Rico.”

An auxiliary cable came loose from a socket on one of the towers in August, creating a 100-foot gash in the dish. Engineers were assessing and working on a plan to repair the damage when another main cable on the tower broke on November 6.

When it broke, the cable crashed into the reflector dish below, causing additional damage.

After the break on November 6, engineers inspected the rest of the cables and discovered new breaks as well as slippage from some of the sockets on the towers. Multiple engineering companies reviewed the damage. They determined that the telescope could collapse because it is “in danger of catastrophic failure” and the cables were weaker than expected.

The latest review revealed that damage to the telescope could not be stabilized without risking staff and the construction team. This led to the NSF making the decision to decommission the telescope after 57 years.

“We believe the structure will collapse in the near future if left untouched,” according to a letter by engineering firm Thornton Tomasetti that assessed the observatory ahead of the decommissioning announcement on November 19. “Controlled demolition, designed with a specific collapse sequence determined and implemented with the use of explosives, will reduce the uncertainty and danger associated with collapse.”

The firm also recommended that this be carried out “as soon as pragmatically possible.”

Those plans were underway when the telescope collapsed.

The NSF said its priorities include safety at the site, conducting a damage assessment and containing or mitigating any environmental damage. The agency will also focus on bringing any ongoing scientific and educational support from the observatory back online.

The foundation will also ensure that Arecibo staff will be paid and make repairs to research tools, such as the roof of the Light Detection and Ranging, or LIDAR, facility and the 12-meter telescope used for radio astronomy research.

The NSF had planned to preserve as much of the observatory as it could to allow the facility to serve as a hub for research and education in the future, as well as restoring operations at the observatory. There is no word yet on how this collapse impacts those plans or if the foundation was able to migrate all of the archival data collected by the telescope to off-site servers.

Of interest is the LIDAR geospace research facility, the visitor center and the off-site Culebra facility for analyzing precipitation and cloud cover data.

A legacy of discoveries

Over the years, Arecibo Observatory has revealed new details about our planet’s ionosphere, the solar system and worlds beyond it.

The telescope has supported and contributed to important discoveries in radio astronomy as well as planetary and solar system research, including gravitational waves.

The Arecibo telescope played a key role in discovering the first planet outside our solar system and has helped astronomers identify potentially hazardous asteroids en route to Earth.

Observations made by the telescope helped discover the first binary pulsar in 1974 (which led to the 1993 Nobel Prize in physics), supported NASA’s Viking mission, produced the first radar maps of Venus’ surface and spotted the first exoplanet in 1992.

More recently, Arecibo detected organic molecules in a distant galaxy and discovered the first repeating fast radio burst.

The observatory, which was featured in the James Bond film “GoldenEye,” was completed in 1963 and has been helmed by the NSF since 1970. It is operated and managed by a team at the University of Central Florida, the Universidad Ana G. Méndez and Yang Enterprises Inc.

The observatory is so beloved and critical to science, there was even a Change.org petition to save the observatory after the decommissioning was announced. It had more than 35,000 signatures.

“Arecibo has been an incredibly productive facility for nearly 60 years,” said Jonathan Lunine, the David C. Duncan professor in the physical sciences, and chair of the department of astronomy at Cornell University, in a statement after the decommissioning was announced.

The telescope was designed and constructed by Cornell.

“For the Cornell scientists and engineers who took a daring dream and realized it, for the scientists who made new discoveries with this uniquely powerful radio telescope and planetary radar, and for all the young people who were inspired to become scientists by the sight of this enormous telescope in the middle of the island of Puerto Rico, Arecibo’s end is an inestimable loss.”

Scientists worry about projects that were in progress using the Arecibo telescope, as well as what it means for future detections — especially of asteroids that come near Earth.

After the decommissioning was announced, NASA made a statement.

“The planetary radar capability at Arecibo, funded by NASA’s Near-Earth Object (NEO) Observations Program, has served as one of two major planetary radar capabilities. It has allowed NASA to fully characterize the precise orbits, sizes, and shapes of some NEOs passing within radar range after they are discovered by wide-field optical telescope survey projects.”

But NASA’s fully operational Goldstone Observatory in California will also be able to characterize these objects, “so NASA’s NEO search efforts are not impacted by the planned decommissioning of Arecibo’s 305m radio telescope.”