To use Newton's words, our efforts up till this moment have but turned over a pebble or shell here and there on the beach, with only a forlorn hope that under one of them was the gem we were seeking.Now we have the sieve, the minds, the hands, the time, and, particularly, the dedication to find those gems—no matter in which favorite hiding place the children of distant worlds have placed them." - Frank Drake (May 28th, 1930 - Present)
Most of you are probably familiar with SETI (the Search for Extraterrestrial Intelligence), but have you heard about the founding father of this institute (which, by the way will likely be responsible for detecting the first traces of intelligent life lurking throughout our home galaxy)? This is Frank Drake's story.
Frank was born on May 28th of 1930 in Chicago. From the time he was just 8 years old, he began scouring the skies, glancing up at stars located hundreds of thousands of light-years from home. Perhaps some of them had orbiting planets that may have the necessary ingredients for life, and an ample amount of time, so that life could get a steady footing. Though Drake frequently imagined this scenario, he was hesitant to discuss the possibilities of intelligent life existing due to the prevalent religious and political ideologies that made holding such a position unfavorable. It wasn't until he enrolled at Cornell University on a Navy Reserve Officer Training Corps scholarship that he began his half a decade long affair with astronomy. It was also here that he began to realize his thoughts about extraterrestrial beings wasn't such a ridiculous notion to consider.
This was reaffirmed after hearing a lecture given by Otta Struve, a prolific Russian astronomer who famously thought extrasolar planets may outnumber the stars in our galaxy, which is now known to be quite likely thanks to the data collected from the Kepler mission.
After graduating in radio astronomy at Harvard, he began a career in radio astronomical research at the National Radio Astronomy Observatory in Green Bank, West Virginia before continuing on to NASA's Jet Propulsion Laboratory that's located in Pasadena, California. It was here that Drake began to spearhead the conversion of the Arecibo Observatory to a radio astronomical facility where he would go on to send a Arecibo message to any alien civilization that may reside near M13, which is about 25,000 light-years away from Earth. You can read more about Drake's arecibo message at this site.
Along with Carl Sagan, Drake helped design the plaques on the Pioneer probes, which were launched on Pioneer 10 and 11 and were the first physical messages sent into interstellar space in hopes of intelligent beings discovering it in the distant future. A few years later, he helped supervise the installation of the golden records on the Voyager probes, which were far more intricate and detailed than those that left the planet on-board the Pioneer probes. You can read about the Voyager Records here.
There is no doubt, Frank Drake is mostly known for developing the Drake equation, which is a mathematical equation that was developed to estimate the number of detectable alien civilizations residing in the Milky Way. Drake was a pivotal part of a meeting that was held in 1961 at the Green Bay facility where the outlines of SETI's organization were laid out. This meeting was attended by many faces including Carl Sagan, Philip Morrison, Dana Atchley, Melvin Calvin, Su-Shu Huant, John C. Lily, Barney Oliver and Otto Struve, who played a small part in Drake's interest in finding any intelligent species that may reside in our galaxy. This team famously came to be known as the "Order of the Dolphin."
Drakes equation (which shouldn't be confused with the Fermi paradox, which discusses the reasons for why we aren't detecting any mysterious signals that may be alien in origin if intelligent beings are out there and within reasonable distances for communication) takes many things into consideration from the rate of star formation, the fraction of stars that have planets, the number of habitable planets circling each star, the fraction of planets that remain habitable long enough for life to evolve all the way up to the number of civilizations that are capable of developing technology that could be matched to ours.
Taking all of that (plus much more) into consideration, Drake estimates that there should be between 1,000 and 100 MILLION civilizations in various stages of development in our galaxy alone! Kind of a crazy number.