At the start of September in Aptos, California, an elderly man slipped peacefully away, almost unnoticed. Aged 92, Frank Drake was one of the founding fathers of SETI ( search for extraterrestrial intelligence). Through his life’s work, he pioneered a scientific approach to a topic that in the early years, was seen as fringe at best and downright crazy at worst.
Ever since humanity looked up in wonder, we have speculated on the possibility of life elsewhere. As our knowledge evolved, it became clear that the amount of stars in our Milky Way was vast. 400 billion is the latest estimate. With numbers like this, the probability of life on other worlds seems inevitable. After all, with hundreds of billions of stars, then surely there must be life…..right. Sure didn’t the aliens crash in Roswell in 1947!!!
By the late fifties and early sixties, the space race was well and truly on. Buck Rogers and Flash Gordon were staples and Captain Kirk was about to be unleashed. This is the world Frank Drake inhabited as a young scientist. Aliens were the entertainment.
His lifelong obsession with life on other worlds led him to formulate his now famous Drake Equation. Put simply, the Drake Equation allows us to estimate, based on our current knowledge, the number of aliens there might be in our galaxy. Speaking of how his equation might have been perceived when he published it in 1961, Drake said that at the time “he was too naive to be nervous.” No matter how it was perceived in the scientific community, it has gained a veneer of respectability over time and has ensured Drake’s name now lives on in perpetuity.
Without going into too much detail, Drake’s equation looks at the rate of star formation; the number of stars that have planets; the number of planets per star that are habitable; the fraction of those planets on which life might evolve; the percentage of that life that might develop intelligence and then become clever enough for interstellar communications, and finally how long such a civilisation might last.
As our knowledge improves we can refine our estimates. We now know the rate of star formation, we know that most planets have stars and that many planets (or their moons) may be habitable. What we don’t know is how often life arises. Is life on Earth a fluke-a one off, or is it inevitable? What about complex life? We don’t know, but we are looking. Just this month, NASA reported finding complex organic chemicals on Mars. Evidence of life? We need to get martian rocks to a lab to find out.
Until then, the question still remains the same. Are we alone in the universe? For the answer; why not dust off your calculator, fire up your internet browser and take the Drake Equation out for a spin.