Our 50 years of searching is equivalent to scooping a single glass of water from the Earth’s oceans to examine it for fish. It is an experiment that could work — but if it fails, the correct conclusion is that there was inadequate sampling, not that the oceans are devoid of fish.
Today, our searches are getting exponentially better. If we are looking for the right thing, it will take only a few decades to conduct a search that is comprehensive enough to be successful or to yield conclusive negative results.
Is there actually someone or something out there for us to find? This is another question without an answer, yet. In the last two decades of my career, what we’ve learned about exoplanets and extremophiles — organisms that inhabit environments once thought to be incapable of supporting life — has made the cosmos appear more friendly to living creatures.
The census of potentially habitable cosmic real estate has continued to expand. This is not the same as knowing that the real estate is inhabited, of course, though that conclusion could be part of our near future. After all, things do look good.
When I was a student, additional planets were just a good theory. Today, it’s beginning to look like almost every star hosts planets — some seem tantalizingly familiar, but some of them are unlike any in our solar system. We used to think that the limits on life were between the boiling and freezing points of water, at neutral pH values, at pressures not too different from those on the Earth’s surface. The detailed study of life in extreme environments has pushed those limits aside.
Life has evolved to thrive in environments that are extreme only by our limited human standards: in the boiling battery acid of Yellowstone hot springs, in the cracks of permanent ice sheets, in the cooling waters of nuclear reactors, miles beneath the Earth’s crust, in pure salt crystals, and inside the rocks of the dry valleys of Antarctica.
What will my granddaughter know about the limits of life before her student days are over? It’s possible that she may learn about a second genesis of life on Mars or within the ice-covered oceans of the moons of Jupiter and Saturn; possible, that is, if we continue our exploration of the bodies of our solar system. As for intelligent life — for that we need SETI.
And what SETI needs is stable funding for the long haul. For our impatient species, even a few decades is a long time, and if we haven’t yet invented the right way to search, the endeavor could take much longer. A successful retirement for me will consist of making sure that my successor, his successor and SETI researchers elsewhere do not have to ride the funding roller coaster that has characterized the first half-century of this scientific exploration.
With no guarantee of success, it is difficult to attract the best minds to a career in SETI. While many, like me, are hooked on the importance and the potential payoff of this research, few are willing to bet their family’s livelihood on it. Some university professors have been able to develop SETI programs, but only after they achieve tenure. This isn’t conducive to determined exploration. And that is precisely what the search needs right now.
After decades of confusion with UFOs and other pseudo-science, Golden Fleece awards and congressional boasts about ending funding for the “great Martian chase,” the surprising exoplanet discoveries today legitimize this scientific exploration. We haven’t yet found Earth 2.0, but most of my planet-hunting colleagues say that it’s imminent. When we do, the next question is going to be: Does anybody live there?
Jill Tarter, an astronomer, retired in May as the director of the Center for SETI research at the SETI institute. She is Bernard M. Oliver chair for SETI at the institute.
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