L: How Long Do They Last?

Abstract

The Drake equation, a commonly-used starting point for discussions about the likelihood of finding extraterrestrial intelligence, is now nearly a halfcentury old. It dates from 1961, a year after Frank Drake made his pioneering radio search for artificial signals from other worlds. That search, dubbed Project Ozma, was a 200-hour scrutiny of two nearby, Sun-like stars for transmissions spectrally situated near the 1420 MHz line of neutral hydrogen, and was conducted with an 85-foot antenna at the National Radio Astronomy Observatory in Green Bank, West Virginia (Drake, 1960; Kellermann and Seielstad, 1986). These efforts to find easy evidence of intelligence in other star systems provoked considerable public interest, including a major article in Saturday Review (Lear, 1960).