The Drake Equation

Understanding the methods for finding life beyond our own solar system

We have long fantasized about being as close to the stars as possible. That is why we climb Everest and look for ways to land on the moon. While some of us are fortunate enough to succeed, others of us begin by using telescopes both on Earth and in space.

Advanced telescopes have peered into patches of the sky for weeks, if not months, and have discovered that other stars are surrounded by their own planets as they form their own systems.

While studying these systems astronomers wonder what sort of planets are these systems made of. We have learned that our galaxy is home to many kinds of different planet/sun systems such as hot Jupiters, warm Neptunes, even super-Earths of lava and diamond.

These planets have expanded our view of where life may be possible but what drives astronomers to study them is to find an answer to the ultimate question: “Is life abundant or are we unique?”

Observatories like the Keck observatory in Hawaii and similar instruments that are being designed will allow scientists, for the first time help characterize these far-off exoplanets to paint a detailed picture of their sizes, orbits, and chemical signatures their atmospheres contain to understand where and how life might exist.

Combined with knowledge from biology, physics, and chemistry we are learning a great deal about how life and planets coevolve. This science is known as “Astrobiology”. Decades before we discovered the first exoplanet, one scientist named Frank Drake asked what we would need to know in order to know whether another intelligent, technological civilization is, or was, or will be out there.

This question gave us a way to estimate the number of technological civilizations that are out there through an equation.

N = R*. fp . ne . fl . fi . fc . L

Where:

N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past light cone);

and

R∗ = the average rate of star formation in our galaxy.

fp = the fraction of those stars that have planets.

ne = the average number of planets that can potentially support life per star that has planets.

fl = the fraction of planets that could support life that actually develops life at some point.

fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations).

fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space.

L = the length of time for which such civilizations release detectable signals into space.

By substituting these variables with values we find appropriate through our discoveries so far we obtain the following equation

N = 1 x 1 x (0.2) x ? x ? x ? x ?

The equation is still incomplete because we haven't yet discovered all the necessary values to fill the equation in to find out what is possible as values for fl, fi, fc, and L.

When astronomers are searching for the answer to the ultimate question: “Is life abundant or are we unique?” the answer is we are still searching as the knowledge of our universe grows so do the possibilities.