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 Congress can help the Puerto Ricans in some other way.”
The Arecibo facility was originally built in 1963 and run by Cornell University under contract to the Air Force Research Laboratory, partly out of a desire to understand the properties of objects like nuclear warheads tumbling through the upper atmosphere. As a result, it was built to be both a telescope and a planetary radar, and many astronomers have used it to map dangerous asteroids as they buzzed past Earth.
For years, it hosted the largest single radio antenna on the planet, only surpassed in 2016 by a new telescope in China that is 1,600 feet in diameter.
One of its early feats, in 1967, was to discover that the planet Mercury rotates in 59 days, not 88 as astronomers had originally thought.
Over time, Arecibo became the flagship for 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, now retired from the University of California, Santa Cruz. He was famous for first pointing a radio telescope at another star for indications of friendly aliens, then for an equation, still in use today, that tries to predict how many of “them” are out there.
On Nov. 16, 1974, Dr. Drake beamed the equivalent of a 20-trillion-watt message toward M13, a cloud of about 300,000 stars some 25,000 light-years from Earth, as part of a celebration of an upgrade to the antenna.