60 years later, is it time to update the Drake equation?

On November 1, 1961, a number of prominent scientists converged on the National Radio Astronomy Observatory in Green Bank, West Virginia, for a three-day conference. A year earlier, this facility had been the site of the first modern SETI experiment (Project Ozma), where famed astronomers Frank Drake and Carl Sagan used the Green Bank telescope (aka "Big Ear") to monitor two nearby sun-like stars--Epsilon Eridani and Tau Ceti.