The legendary Frank Drake coined the search for extraterrestrial life

Frank Drake, A The leading figure in planetary astronomy and astrobiology who inspired the search for extraterrestrial intelligence, or SETI, died Friday, September 2nd at the age of 92 SETI experiment,” said Bill Diamond, president of the nonprofit SETI Institute in Mountain View, California.

Drake was born in Chicago in 1930. He studied engineering physics at Cornell University and then served for three years as an electronics officer on a Navy cruiser. He then earned his PhD in astronomy from Harvard.

His SETI quest began in 1960 while he was working for the National Radio Astronomy Observatory on its telescopes in Green Bank, West Virginia. Unbeknownst to him, a pair of physicists had published research in 1959 speculating how far radio signals sent by extraterrestrial civilizations could travel and still be picked up by a receiver on Earth. “It turns out the distance is light-years,” says Seth Shostak, principal astronomer at the SETI Institute, a nonprofit research organization focused on the origins and search for extraterrestrial life. “Maybe the sky is full of signals, but we just never looked for them.”

Drake had already begun leading an effort to do just that. In 1960 he secured NRAO approval for Project Ozma (named after the Princess in The Wizard of Oz), the first attempt to systematically hunt for extraterrestrial signals. For a few hours each day, he aimed the facility’s 85-foot radio telescope at Tau Ceti and a handful of other nearby star systems, looking for bumps or wobbles above the background noise that could be signs of intentional transmission. He tuned into a specific range of frequencies, specifically one near the 21-centimetre emission line of hydrogen. This is typically a quiet part of the radio spectrum – most worlds would have few emissions in this area – so one could use it as a natural “calling” frequency. But apart from a false alarm, which probably came from an airplane, all he and his colleagues heard was static.

Although the Green Bank experiment didn’t detect extraterrestrial messages, it did show how to look for them, so the National Academy of Sciences approached Drake to help organize a conference there on SETI. This pivotal 1961 meeting brought together an influential and diverse group of scientists, including chemist Melvin Calvin (who was notified of his Nobel Prize win at the meeting), a dolphin intelligence researcher, the authors of the 1959 paper, and a young Carl Sagan, who became a frequent collaborator of Drake.

At this conference, Drake began developing a groundbreaking formula that later became known as the Drake equation. This formula is still widely used today in various forms, trying to come up with an approximate number for the number of extraterrestrial societies that might exist in our galaxy and that might be trying to send us a message. Its variables include the birth rate of stars, the abundance of planets orbiting them, the proportion of rocky worlds that are habitable, the proportion on which life could develop, the proportion of extraterrestrial civilizations that could transmit signals that can be detected , and the estimated lifespans of these civilizations.

While the variables about stars and planets can be constrained with some precision, no one really knows how long intelligent civilizations typically last. (After all, we only have Earthly civilizations to extrapolate from. Though some have thrived for millennia, cosmically speaking humans are just babies — and they’ve already threatened their very existence with nuclear war and climate change, and still don’t know how to distract killer asteroids.) “Most important terms of the equation are unknown. You could say, ‘The equation is useless,’ but that’s not true because it’s a good way to organize your ignorance,” says Shostak. It shows that questions about intelligent life and our efforts to listen to it must also bring other fields together, including astrophysics, geology, biology and sociology.

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