One of the world’s most famous radio telescopes is on the verge of disaster, sparking a frantic race by engineers at the Arecibo Observatory in Puerto Rico to rescue it after two important cables supporting a 900-ton equipment platform broke down.
The platform, which is fixed high above a huge dish by cables fixed to the towers, must be installed quickly, otherwise it may collapse to the ground and destroy the telescope. With these two cables lost, the remaining cables are under increasing pressure, and it is uncertain whether the rescue effort will succeed.
“For me, it might be 50,” says former observatory director Michael Nolan, who currently works at the University of Arizona. They are doing what can be done. I’m still really worried that they just can’t do enough. If we are worried about it falling, nobody should go up there or be there when that happens. “
Suspended from three towers, the telescope platform hovers approximately 500 feet over the 1,000-foot-wide plate. In August, an additional cable slipped out of its socket and fell into the plate, carving 100 feet into the mirroring panels. Before the crew could repair that cable, another cable connected to the same tower was torn on November 6. This second broken cable is one of the four primary cables connecting this tower to the platform.
“I wasn’t so worried when the first cable failed because I was confident it would take a few months to fix it,” says Abel Mendes, an astronomer at the University of Puerto Rico in Arecibo who frequently observes with telescopes. But Mendez says he was stunned when the second cables broke. “Now I’m worried.”
Arecibo has played an important role in discovering planets outside our solar system, searching for civilizations beyond Earth, and studying asteroids and other worlds closer to their home. Today, scientists use the telescope to study powerful bursts of energy called fast radio bursts and to spy on ripples in the fabric of space-time resulting from colliding galaxies.
Each observatory tower has four primary cables, but only two cables are required to keep the platform elevated – assuming it is in good condition. The fourth tower (named because it’s 4 o’clock if it is noon north) has now reduced to just three primary. If one of these cables fails, it is unclear whether two old cables will be able to secure the platform.
“It’s an ugly situation for sure,” says Frank Drake, the former Arecibo manager (and dad). “When the cables break like this, it can at any moment cause a chain reaction with more broken cables, and the fall of the whole thing.”
That would be a huge blow to ongoing scientific observations – and to Puerto Rico, where the observatory is a source of pride, providing jobs, attracting tourists, and sharing resources with surrounding communities, especially during emergencies like Hurricane Maria.
Several engineering companies and the U.S. Army Corps of Engineers are working on the ground to assess the vulnerable platform, while daily drone inspections provide updates on cables. Teams are exploring ways to stabilize the chassis, including removing some weight from the platform using helicopters, de-stressing the system by lowering the platform, and reconnecting the auxiliary fallen cable, which remains largely intact after slipping out of its socket.
“We will likely know fairly soon if they can come in with first aid, de-stress some of the tension, and remove the urgent problem so that we can fix the big problem,” Nolan says.
In the 1960s, engineers built a giant Arecibo radio dish in a Puerto Rican landscape. The triangular overhead gear platform helps guide the telescope toward different parts of the universe. This platform is packed with receivers, linear feed feeders, and a complex inverter system that precisely focuses on radio waves – which is where James Bond fought Alec Trevelyan in 1995. Golden eye.
Although it may seem small in relation to a plate, the suspended structure is really huge – a small home can easily fit within a dome housing a reflector system.
The platform is anchored by 18 thick steel cables linked to three concrete pylons, the tallest of which is 365 feet. In addition to the four core cables in each tower, two additional accessories were installed to each tower in the 1990s to help stabilize the structure and carry additional weight.
Observatory personnel regularly check towers, cables, and platform for signs of weakness or corrosion caused by the salty tropical air.
“There is nothing worse than corrosion from salt fog,” says Dennis Egan, an engineer at the Greenbank Observatory in West Virginia. “You’d better be underwater.”
These inspections have revealed some evidence of interrupted leads in the cables, a problem Nolan is suspected to have been exacerbated by Hurricane Maria and a swarm of recent massive earthquakes. But they found no signs of widespread weakness or imminent failure. In a Q&A posted to Facebook, Arecibo manager Francisco Cordova said the rupture was unexpected and indicated structural deterioration.
“I don’t want to be a 50-year-old observatory,” says Drake, who became famous for sending a message to outer space from the observatory in 1974, “and there’s never been a situation where a whole bunch of different threads suddenly unravel.” On this thing now. There is no escape. You’re just stuck. “
If the fourth tower fails, the platform can either collapse through the plate or swing drooping down a nearby slope. Without the weight of the platform keeping the balance of the towers, the three could have capsized in the surrounding woods.
If engineers can install the structure, then they can repair or replace some of the old cables. Cordova said on Facebook that the new cables are already in order and are due to arrive at the observatory in December.
But to replace the cables, workers will need to climb onto the platform. “They have to do something to verify that the cables that are in are correct and not damaged, in a way that does not put people on the structure at risk,” says Drake.
Scientific and cultural icon
Arecibo has faced a number of challenges in recent years, including threats from the National Science Foundation to cut funding. But the scientists and surrounding communities rallied, and the University of Central Florida stepped in to run the besieged observatory.
Now, many are wondering if NSF will help Arecibo during this emergency. According to Córdova’s social media post, NSF is reviewing an application for $ 12.5 million to fund the reform.
NSF is in contact with Arecibo. “We are monitoring the situation and looking at all possible options to accelerate the stability of the structure,” the agency said in a statement. “Our top priority is the health and safety of Arecibo employees.”
Despite its current troubles, the observatory has a long and rich history, and it holds a proud place among scientists and Puerto Ricans.
“It has anchored itself in our Puerto Rican culture, in the fabric of our everyday life,” says Edgard Rivera Valentine of the Lunar and Planetary Institute, who helped his grandfather build the telescope. “I definitely have a memory of being hit by this huge machine, right here, and I know the people in my city were doing all these really cool things,” says Rivera Valentine. “I am into science because I grew up near the observatory.”
The discoveries from Arecibo include the 1974 discovery of a pair of circular pulsars that emit gravitational waves – winning the Nobel Prize in Physics in 1993 – and the first confirmed planets to be observed orbiting a star other than the Sun in 1992. Scientists at Arecibo also worked on Mercury’s rate of rotation, they observed A rapid, frequent radio explosion, and multiple searches for communicative civilizations beyond Earth – an endeavor popularized by Carl Sagan’s novel call Which was later made into a movie of the same name.
In addition to observing the sky and collecting radio waves, the Arecibo is also a very powerful radar. Scientists use this ability to characterize asteroids that cross Earth’s orbit, and calculate their locations with great accuracy to see how to avoid future collisions. And in 1974, my father used it to send an interstellar message to a group of stars called the Great Cluster in the constellation Hercules. In it, he coded information about humans, the Earth, the solar system, and Arecibo, and broadcast it during the celebration of telescope upgrades.
“She does atmospheric sciences, solar system sciences, astronomy, and astrophysics,” Rivera-Valentine says. “It is important to science and the world at large.”