The Hopeful Search for Extraterrestrial Life

>Fifty years ago, the search for intelligent life in the universe began in earnest. That year, an astronomer at the National Radio Astronomy Observatory named Frank Drake began scanning the stars with a radio telescope, hoping to find evidence of a civilization we could communicate with. This was the first iteration of the famed SETI program, and it was the beginning of "the most ambitious, and potentially the most significant, research project in history," writes Paul Davies in The Eerie Silence: Renewing Our Search for Alien Intelligence. And thus far it's been spectacularly unsuccessful. Despite a half century of intensive effort, not a single extraterrestrial bacterium has been definitively identified, let alone an intelligent species.

Yet these are buoyant times among alien enthusiasts--and not just the usual cranks. A recent poll by Scripps Howard and Ohio University found that 56 percent of American adults think intelligent life likely exists elsewhere in the universe. Mainstream media coverage of UFOs and other extraterrestrial happenings has skyrocketed in the last 10 years. And no less an authority than Stephen Hawking asserted this spring that he believes intelligent species almost certainly exist (and should probably be avoided). But optimism is also surging among serious scientists involved in the quest for extraterrestrial life, a small sampling of whom sat on a panel convened by the World Science Festival last night in Brooklyn.

Their common theme was that relentless technological advances have both deepened our appreciation for the number of potentially habitable worlds and extended our ability to investigate them. Steven Squyers, the principal investigator on NASA's Mars rover missions, revealed that a new analysis of rocks studied by the Spirit rover found high concentrations of carbonate--suggesting not only that water likely existed on ancient Mars, but that it had low-enough acidity to support life. "Of all the discoveries rovers have made over the six and a half years they've been on Mars, this one points toward more life-friendly conditions than anything else," Squyres said. "This is strange stuff, not like anything we've seen before." He added that the possibility of life on Jupiter's moon Europa, which is coated by an ice sheet that scientists suspect covers a liquid ocean, also seemed increasingly likely. Finding life in either place--thus proving that organisms emerged independently more than once in a single solar system--would suggest that it was propagating on a vast scale across the universe.

Michael Russell, a geologist at NASA's Jet Propulsion Laboratory, argued that according to his theory of how life began on earth--summarized here--it was a virtual certainty elsewhere in the universe. On wet, rocky planets "life will automatically onset," he said.

And the universe outside our solar system seems to abound with potential homes. David Charbonneau, a professor of astronomy at Harvard, pulsed with optimism as he described NASA's Kepler mission, which launched last year and will examine 100,000 stars in a search for orbiting planets. Because the technology for detecting these so-called exoplanets has improved dramatically, this is "really a remarkable time to be alive," he said. "If those planets are out there, we should be finding them pretty soon." And if any seem habitable, scientists will study the chemical content of their atmospheres for the hallmarks of biology.

Of course, for 50 years believers in alien life have subsisted on nothing but optimism. And Jill Tarter--the SETI astronomer who inspired the character played by Jodi Foster in Contact--suggested a measure of caution. She analogized SETI's search for intelligence over the years to examining a single glass of water from the earth's oceans in a search for fish. But as SETI's technology improves--particularly as the ambitious Allen Telescope Array comes online--she believed that making contact with alien civilizations was increasingly feasible, and that humankind should have a clear plan in place for how to respond to them. "Computing power is getting exponentially better," she said. "Frank Drake in 1960 conducted the first radio search looking at two stars with a spectrometer that had one channel. Today I look at multiple stars with spectrometers that have hundreds of millions of channels. The tools I use today are 14 orders of magnitude more comprehensive than what we started with 50 years ago. And 50 years in the future--unimaginable."