Anybody Out There? 

Bay Area scientists scour Earth and skies for clues to an ultimate question. In Search of Life: First of a Two-Part Series

It was, without a doubt, the biggest party ever thrown in a NASA Ames Research Center aircraft hangar. One evening in April, as electronic band Telefon Tel Aviv twiddled and blurbled away, thousands of beglittered, oddly coiffed people danced to celebrate the launch date of Soviet cosmonaut Yuri Gagarin, the first man in space. It was hard to tell the NASA employees from the rave kids, since, in an homage to space science, many of the dancers were clad in lab coats and flight jumpsuits.

Pete Worden, director of the center, who took the stage around midnight urging the crowd to "party like it's 1961," appeared to be wearing a wizard outfit. And when the band decamped from the cable-strewn stage so that NASA planetary scientist Chris McKay could tell them all how to hunt for life on Mars, everyone stopped dancing long enough to listen.

McKay was a grad student when Viking landed on Mars in 1976 and sent back news that although many of the necessary components for life were there, life itself wasn't. He has devoted his entire career to finding out whether Viking was wrong.

What he wants to discover on Mars, McKay told a rapt crowd, is a "second genesis" — proof that life arose independently in more than one place in the universe. "Life," he specified, "but not as we know it."

When McKay started his career, that kind of talk was the province of Trekkies and tinfoil-hat wearers. Now it's a serious science, and you can hardly talk to anyone in the field of what's now called astrobiology without them tipping their hat to McKay's pioneering work.

"For a long time I was sort of a voice in the wilderness," McKay muses a few weeks later from the comparative calm of his office at NASA Ames in Mountain View.

But in the mid-'90s, he says, three watershed events hinted that scientists might be on the verge of unpacking some of the universe's more enduring mysteries: The Hubble Space Telescope began beaming back pictures from deep space; researchers identified, for the first time, a planet outside our solar system; and scientists published a paper claiming they'd found traces of life in a Mars meteorite that had smashed into Antarctica. Even though that claim was later debunked, McKay recalls that these events whetted public interest and convinced NASA to fund research into how and where life could begin. "That's when astrobiology became flavor of the month," he says. "That's when I no longer had to start my lectures with explaining why NASA was looking for the origin of life."

In fact, astrobiology has been the flavor of the last decade, particularly here in the Bay Area where UC Berkeley, San Francisco State, and NASA Ames Research Center have led the field in trying to answer the kinds of mind-boggling questions prompted by the search for life in space. Is our planet an aberration, a warm spot in a cold universe — or is life practically inevitable if you throw the right chemicals together? If there's other life, what's it like? Where does it live? Is it related to us? Why doesn't it ever call or write?

The simplest answer could be that we are indeed all alone. That's the "Rare Earth" hypothesis, put forth by professors Donald Brownlee and Peter Ward from the University of Washington. Their 2000 book, Rare Earth: Why Complex Life Is Uncommon in the Universe, argues that our planet is the happy beneficiary of an extremely unusual chain of circumstances that made the rise of intelligent life possible, and which is unlikely to be repeated again.

Earth lucked into being born at the right part of the galactic disc in the right orbit around the right kind of star, and just happens to be of the right size and composition to have an atmosphere that can support carbon-based life. It also has many traits that allowed not only life's genesis, but its continued survival: protective magnetic fields, useful plate tectonics, and the stabilizing influence of a large moon, to name a few. While microbial life might be common throughout the universe, the authors argue, animal life isn't.

Some astrobiologists consider this a flawed argument, overly based on a terrestrial understanding of what life requires. When you consider the vastness of space, they say, Earth isn't likely to be that special. But the only way to prove the Rare Earthers wrong is to go out and find some aliens, an enormous task.

Astrobiology is an untidy field as it is, encompassing everything from galactic evolution to the evolution of microbes. By necessity, it is interdisciplinary — it has attacked its core queries with the tools of astrophysics, biology, chemistry, geology, and paleontology. Yet because astrobiologists are in the unique position of theorizing about life on landscapes they will never visit, their explorations must be done by proxy.

Here's the idea: There are places on Earth that make good stand-ins for other parts of the solar system; the Martian permafrost, say, or the icy brine of Jupiter's moon Europa. These places are almost unrelentingly nasty for humans and were once considered lethal to all life. Yet everywhere astrobiologists have looked on our own planet, life has a toehold. In some of these forbidding places, it is thriving.

Work over the last decade has greatly expanded our notion of where organisms might be found, and has fed a growing conviction that life, with its resiliency and adaptability, is probably very common in the universe. Yet the proof, McKay says, will be in the Petri dish: "It's like the Europeans wondering if there was an edge to the Earth or if there were dragons in the Sargasso Sea. The only way to find out was to go look."


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