The site was also highly regarded by visiting astronomers who went there to investigate.
Jill Tarter, perhaps the world’s leading alien seeker, now retired from the SETI Institute in Mountain View, California, enthusiastically expressed herself in an email about “the constant croaking of cokes, the perfumes of the rainforest,” as well as of the path to run under the plate surrounded by orchids and Orion towering over the treetops. But he said that what he would miss the most was “the staff and resident scientists who were very close, gave us excellent technical support and organized wonderful parties with lots of dancing.”
Dan Wertheimer of the University of California, Berkeley, a leader in the search for extraterrestrial intelligence, wrote in an email: “Arecibo has made profound discoveries, helping Earthlings understand our planet and the universe.”
He added: “I hope that Congress can help Puerto Ricans in some other way.”
Built in 1963, the Arecibo facility was originally managed by Cornell University under contract with the Air Force Research Laboratory, in part out of a desire to understand the properties of objects such as nuclear warheads falling through the upper atmosphere. As a result, it was built to be both a telescope and a planetary radar, and astronomers also used the observatory to map dangerous asteroids as they passed Earth.
For years, the site housed the largest single radio antenna on the planet, second only to a new telescope in China in 2016 that is just under 500 meters in diameter.
One of his feats, in 1967, was to discover that the planet Mercury completes its rotation in 59 days, not 88, as astronomers had initially thought.
Over time, the Arecibo observatory served as the flagship of the Search for Extraterrestrial Intelligence, or SETI, the optimistic quest for radio signals from alien civilizations.
One of its directors was astronomer Frank Drake, then at Cornell and now retired from the University of California, Santa Cruz. He was famous for first pointing a radio telescope at another star for signs of friendly aliens, then for an equation, still in use today, which tries to predict how many of “them” there are.