Life on Titan? Exploration to begin


Published: Friday, January 14, 2005 at 6:01 a.m.
Last Modified: Friday, January 14, 2005 at 1:24 a.m.
When the parachute opens and the Huygens spacecraft beings its descent toward the Saturn moon of Titan today, Steven Benner will be among those anxiously awaiting data.
Part of the multibillion-dollar Cassini mission - jointly operated by NASA, the European Space Agency and the Italian Space Agency - the Huygens craft and its planned exploration are being watched closely by scientists searching for life on other planets.
Larger than Mercury and slightly smaller than Mars, Titan is the only moon in the solar system with a substantial atmosphere, making conditions ripe for such intergalactic discoveries.
But Benner, a University of Florida chemistry professor, won't be limiting his search to the conventional definition of organic existence.
Life in outer space, he says, might look nothing like it does at home.
"Weird life," as he calls it, "is the kind of life that might be different from the kind of life we encounter on Earth," Benner said from his office in Gainesville this week.
"We might not have the ability to recognize it."
While endlessly diverse, life on Earth obeys a series of set rules. Water, for example, is required by all living organisms to survive, and the only places where life is absent are areas where moisture is scarce or nonexistent.
This common thread has served as the operating theory for past missions searching for life on other planets, Benner said, including NASA's recent journey to Mars. Landing sites selected for the Opportunity and Spirit rovers, for example, were in areas where mineral deposits were believed to once have been associated with water.
But a growing number of scientists have begun to ask whether life beyond Earth's atmosphere would have to follow the same water-dependent rules.
Benner, who serves on a National Academy of Sciences committee considering just how weird life could be, doesn't think it would.
One theory he and others are exploring is the possibility that liquid hydrocarbons, such as methane and propane, could support life. Titan, which is blanketed by a haze of methane some believe is a byproduct of a liquid hydrocarbon ocean, could be a good place to test such a hypothesis, Benner says.
Benner also is re-examining the conventional understanding of genetics in his search for "weird life."
On Earth, genetic information is stored in DNA, and requires RNA to make proteins.
When RNA was first discovered, scientists believed it was nothing more than a cellular messenger. But later research found it could carry out tasks similar to proteins, prompting some to speculate that life evolved from simpler organisms that used only RNA.
If true, Benner says such organisms still may be hiding out somewhere on Earth, and hold clues to possible life-forms on other planets.
"We're going to be looking where we land," Benner said of the Huygens' planned study site, and whether that mission might help answer some of his "weird life" questions.
"This really is, as they say, a fishing exploration," he said.
Still, even if everything goes smoothly - Huygens first must descend to Titan safely before data is sent home - Benner acknowledges he has no idea what to expect.
"The greater expectation is . . . that you'd expect to find no life," he said. "We don't know of any life that can survive in that environment."
But, he added, "No one will be more surprised than I would be if we find little green men" waiting for Huygens when it lands.
Greg Bruno can be reached at (352) 374-5026.

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