On July 11, 2022, the James Webb Space Telescope (JWST) returned its first images, penetrating the wall of time to show us the universe a few hundred million years after its formation.
In a marvelous cosmic irony, this immersion into our planet’s origins actually propels us into the future, where a revolution looms in the search for life in the universe.
We live in a golden age in astrobiology, the beginning of a fantastic odyssey in which much remains to be written, but where our first steps promise prodigious discoveries.
These first steps have already transformed the ways in which we consider life on planets beyond our own.
As the chief scientist of the SETI Institute in Mountain View, Calif. — the world’s leading center for the search for extraterrestrial intelligence — I am convinced that finding life beyond Earth is not a matter of if but a matter of when.
And as the SETI Institute celebrates its 40th anniversary, the time for such a discovery seems to be increasing closer.
As recently as May of this year, scientists discovered a new potentially habitable planet, Gliese 12 b, just 40 light years away.
This Earth-sized exoplanet, identified using NASA’s TESS satellite system, orbits a cool red dwarf star and shares intriguing similarities with Venus.
Signs of habitability are seemingly everywhere. But what about actual life?
To begin with, the elementary compounds making life as we know it — carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur — are surprisingly common.
It is no accident that we humans are made of them.
This is the star stuff astronomer Carl Sagan always talked about — not the aliens of Hollywood’s imagination.
This is life — or the building blocks of life — ever-present, but invisible to the human eye.
Thanks to decades of astronomical research, we know these organic molecules and volatiles are found on Mars, in the plumes of Saturn’s tiny moon Enceladus, in the atmosphere of Titan, on comets and more.
We discovered them on asteroids and the dwarf planets Ceres and Pluto, and these are only a few examples.
Much farther away still, nearly 200 hundred types of prebiotic organic molecules have been detected over decades of astronomical observation in interstellar clouds near the center of our galaxy.
They include the kinds of molecules that could play a role in forming amino acids — those building blocks of life.
The sheer number of potential alien worlds adds to the probability that life could be abundant in the universe.
Data received from Kepler space telescope missions since its launch in 2009 suggest that tens of billions of Earth-sized planets could be located in the habitable zone of sun-like stars in our galaxy alone.
Because the probability distribution in nature predicts more puddles than large lakes — more small buttes than Himalayas, more small planets than large ones and more simple life than complex life — the universe is likely teeming with planets harboring that simple life.
Even if only one in a billion of those planets has developed life that’s made it to higher levels of complexity and intelligence, nearly a dozen advanced civilizations could populate our entire galaxy.
Even if it were only one per 100 galaxies, there could still be billions of them throughout the cosmos.
The universe has produced the elements which are the necessary for life for a very long time, as demonstrated by JWST, which discovered complex organic molecules in a galaxy more than 12 billion light-years away back in 2023.
Still, life developed on Earth, and maybe elsewhere, possibly because these elements started to become sufficiently abundant only during the creation of the youngest population of stars.
If life as we know it is indeed only possible only on these younger stars, then the universe could just be starting to blossom with cradles of life.
Today, we might still not know exactly where we are heading and what we are looking for, but it does not really matter.
Answers will present themselves as we go.
What truly matters is that we have set sail.
We are now on the most remarkable journey humanity has ever undertaken, searching for our origins and for a cosmic echo that will finally tell us one day whether we are alone.
Dr. Nathalie Cabrol, Science Director of the Carl Sagan Institute at SETI and the author of The Secret Life of the Universe: An Astrobiologist’s Search for the Origins and Frontiers of Life.
