We do constrain the Drake equation when we know more. It&#x27;s just that we don&#x27;t know a lot.<p>We have come to know the number of stars around pretty well - at least in our galaxy. Thanks to Kepler and other exoplanet hunters, we know know alot more about the number of planets. These findings are used to constrain the Drake equation.<p>The rest of the parameters we don&#x27;t know much about, yet.