Frank Drake Totally Saw Kepler-452b Coming

On the day NASA announced it had found the most Earth-like planet yet, I made first contact with Frank Drake, the world’s most famous alien hunter, via his AOL email address. Drake has spent 55 years looking for extraterrestrial life. In 1960 he conducted the first scientifically rigorous attempt to find aliens (by listening with a radio telescope), and in 1961 he convened a meeting of all the experts interested in finding them. “I invited all 12 of them,” he told me.

Now there’s a whole lot more people looking. On Thursday, NASA revealed Kepler-452b, a clunkily named planet about 1,400 light years from us that just might have what it takes to give life a home. Kepler-452b isn’t identical to Earth — it’s 60 percent larger and takes 20 days longer to orbit its star, which is brighter than ours — but its discovery brings the number of small, potentially habitable planets detected by the Kepler space telescope to 12.

I wondered: what did the pre-eminent searcher for alien life make of the latest planetary news? “It just reinforces what we’ve believed all these years — that what happened in the history of our solar system was in no way unusual and required no freakish events,” Drake told me. “What happened here is going to happen in many places.”

Drake made a name for himself with an equation he wrote to prepare for that 1961 meeting. “There were seven things we needed to know to predict how lengthy and difficult the search would be,” Drake said, and those seven things became the meeting agenda. They would also form what’s become known as the “Drake equation,” which calculates the number of alien civilizations we could detect.

$$\text{N}=\text{R}^{*} \cdot \text{f}_{p} \cdot \text{n}_{e} \cdot \text{f}_{l} \cdot \text{f}_{i} \cdot \text{f}_{c} \cdot \text{L}$$

It looks impenetrable, but it’s really just a logical approach to finding the number of civilizations out there in the Milky Way galaxy. (That’s the N you’re solving for.) First you factor in where you think life could be (R*, fp and ne), then you take into account whether life really did emerge in those habitable places (fl and fi), and then you add a dash of complexity — can the life be detected somehow from space (fc and L)?1

The formula couldn’t spit out an actual number because the values plugged into it were “pure guesses,” Drake said. He meant it to provide a framework for thinking about the search for alien life, not means for calculating an exact figure. Drake has always been convinced that it exists, so the probability is about whether we’ll find it.

In the five decades since Drake created the equation, we’ve discovered enough to make better guesses. Five of the seven variables have become much better understood. For instance, the Kepler space telescope that found Kepler-452b was launched in 2009 specifically to search for habitable planets and has shown us that most stars have planetary systems, which gives us a number close to 1 for fp and increases the odds of finding life.

Drake is absolutely convinced that there’s other life in the universe, and he’s optimistic that we will find it, or our children or their offspring will. Kepler-452b looks promising enough, but there are sure to be others, and probably even more promising ones. Still, would we recognize alien life if we did find it? Drake thinks so. “They will not be duplicates of us, but they will have many of the abilities that we have,” he said, such as appendages like arms and hands that allow them to build things. Life on Earth gives us some glimpse of the diversity we might find elsewhere, Drake said. “I would have never thought of centipedes or jellyfish or giraffes — giraffes are unreasonable.”

Drake’s Search for Extraterrestrial Intelligence Institute, or SETI, has been looking for extraterrestrial life for decades. But paltry funding, gathered through donations, has limited the extent of the work. Recently, though, Silicon Valley technology investor and physicist Yuri Milner announced that he is donating \$100 million through the Breakthrough Initiatives to fund SETI programs. (Stephen Hawking was in attendance.) Drake is one of the team members, and the project will use radio telescopes to search the sky for signs of alien life.

If they find something, it will completely change our view of the universe and our place in it, and like many a kid who’s spent a summer evening looking up at the sky, I can’t help dreaming of what it would be like to find life in one of those far-off places. Given the vast number of planets that inhabit our universe, the variables in the Drake equation representing places suitable for life could be huge, and it seems entirely reasonable that life has evolved elsewhere, too.

But if we find something, are we going to be sure of what we’ve found, much less have a way to practically communicate with it? Kepler-452b is 1,400 light years away; in the time it would take to communicate with 452b, Drake’s AOL email account would become archaic 70 times over. Technology moves quickly; our interplanetary communication does not.

Drake imagines the possibility that we might someday find civilizations more advanced than ours — ones that could teach us their time-worn lessons. Some people have hypothesized, he said, that there’s a galactic Internet where we might access all the knowledge and accomplishments of other civilizations, including some that are millions of years ahead of us. “We could study the archaeology of the future,” Drake said. If we could tap into that, we might discover what the future holds for us. Do civilizations like ours last? Or are we living in a particular moment in time? Those are questions a formula can’t answer.

## Footnotes

1. The full rundown of the variables:

• N = The number of civilizations in the Milky Way galaxy that we could potentially detect via electromagnetic emissions.
• R* = The rate at which stars suitable for the development of intelligent life are formed.
• fp = The fraction of those stars with planetary systems.
• ne = The number of planets, per solar system, whose environment is suited for life.
• fl = The fraction of suitable planets on which life actually evolves.
• fi = The fraction of life-bearing planets on which intelligent life emerges.
• fc = The fraction of civilizations that develop a technology that releases signs of their existence that can be detected from space.
• L = The length of time such civilizations release signals.

Christie Aschwanden is FiveThirtyEight’s lead writer for science. Her book “Good to Go: What the Athlete in All of Us Can Learn from the Strange Science of Recovery” is available here.