On November 16, 1974, eight years before E.T. did the “Phone Home” thing on film, researchers send humanity’s first real-life, deliberate radio message into outer space to extraterrestrials. The message goes out from the Arecibo Observatory in Puerto Rico, where the Arecibo radio telescope was getting a major upgrade and conducting a ceremony to mark the upgrades.

Nobody responded to the message. But the researchers, wanting to showcase humanity’s technical advancement, weren’t expecting an answer.

“It was strictly a symbolic event, to show that we could do it,” Donald Campbell, professor of astronomy at Cornell University, told the Cornell Chronicle in 1999. He was a research associate for the Arecibo Observatory at the time.

The transmission—created by astronomers Carl Sagan and Frank Drake—consisted of a simple, visual message aimed at possible intelligent life in the globular star cluster called M13. This cluster is at the edge of the Milky Way, some 21,000 light years from Earth. The message included the formula for DNA, a crude diagram of the solar system, a drawing of the Arecibo telescope and a stick figure of a human.

As for the Arecibo telescope, it shaped cosmic research for six decades, but collapsed in 2020 after two cable failures. Two years later, the National Science Foundation announced it would decommission and dismantle it, replacing it with an education center. At the 2021 Lunar and Planetary Science Conference, presenters wrote that Arecibo “left an indelible mark on planetary science, radio astronomy and space and atmospheric sciences.”