“You have a telescope down”, was announced that evening to the director of the observatory located in Virginia, George Seielstad. “Down” would normally have meant “down”. But not this time: the “saucer” 91 meters in diameter had completely collapsed, without warning, creating a pile of cables and metal that left no hope of reconstruction.
This time at least, in Arecibo, on the island of Puerto Rico, there were warnings. On August 10, a first cable left its anchorage. Engineers then assessed that the entire structure was stable.
But the loss of a second cable on November 6 – the fall of which left a hole in the saucer located below – first led to access to the buildings being prohibited. And finally, to announce the final closure on November 19. The National Science Foundation and the University of Central Florida, which operate the facility, said in a statement they saw no alternatives to stabilize the structure “without endangering lives.”
The scientific structure in question, suspended above the “saucer”, weighs 900 tons.
The Arecibo radio telescope has, since 1963, been used as much to study the Earth’s upper atmosphere as to observe distant galaxies and pulsars, in addition to having contributed to drawing up a list of asteroids likely to pass dangerously close to us. But the image that some of the public will retain remains that of the film Contact, where a team of astronomers was listening for possible signals sent by an extraterrestrial civilization – a type of research that was also carried out there.
Since November 19, astronomers from around the world have shared their memories and regrets. Arecibo was for years the largest single radio astronomy antenna in the world, surpassed only in 2016 by the “500-meter-aperture spherical radio telescope” in China.
It had already almost been closed in 2007, if the National Science Foundation had not found a financial partner. The fate that will be reserved for the site is not yet clear: whether the structure collapses or not, the building reserved for visitors, which is away, could itself remain – Arecibo has been a source of tourist income. for Puerto Rico. But while Green Bank would, 15 years later, inherit a new radio telescope, the prospect of building a second Arecibo in the same location seems much less plausible in the current political climate.