FRANKFURT, Germany (AP) -- Saturn's largest moon
contains all the ingredients for life, but senior scientists studying data from
a European probe ruled out the possibility Titan's abundant methane stems from
living organisms.
More than a week after the Huygens probe plunged
through Titan's atmosphere, researchers continue to pore over data collected for
clues to how the only celestial body known to have a significant atmosphere
other than Earth came to be and whether it can provide clues to how life arose
here.
Initial findings have revealed an abundance of
methane on the surface of Titan - the first moon other than Earth's to be
explored - which is crucial to supporting its thick atmosphere. But
scientists are still puzzling over the origin of the methane.
"This methane cannot be coming from living
organisms," Jean-Pierre Lebreton, mission manager for the Huygens probe that
landed on the surface of Titan Jan. 14, told The Associated Press on Wednesday.
Images snapped by the 340-kilogram (750-pound) probe
as it parachuted through Titan's atmosphere from the Cassini orbiter show the
moon's surface was cut by a weather system leaving deep river beds and large
reservoirs, implying activity by liquid methane.
But unlike water in the Earth's atmosphere that
continually renews itself, methane is destroyed by ultraviolet light, so Titan
must have a source deep inside, scientists said.
Based on data collected by Huygens' instruments,
Sushil Atreya, a professor of planetary science at the University of Michigan in
the United States, believes a hydro-geological process between water and rocks
deep inside the moon could be producing the methane.
"I think the process is quite likely in the interior
of Titan," Atreya said in a telephone interview.
The process is called serpentinisation and is
basically the reaction between water and rocks at 100 to 400 degrees Celsius
(212 to 752 degrees Fahrenheit), he said.
While these discoveries are breaking new
ground - scientists have been surprised by the amount of data they were
able to collect from Titan's surface during the mission - researchers are
far from helping to explain how life may have formed during Earth's earliest
years.
Titan has the ingredients for living organisms,
including nitrogen, methane and water, but not in the right combinations. Far
more information is needed to glean any insights into activity on young Earth,
Atreya said.
"Just looking at the data we have now, I think it's a
long shot," Atreya said.
Huygens was spun off from the Cassini mother ship on
Dec. 24. The euro2.4 billion (US$3.3 billion) Cassini-Huygens mission to explore
Saturn and its moons was launched in 1997 from Cape Canaveral, Florida - a
joint effort between NASA, the European Space Agency, and the Italian space agency.
The probe was named after Titan's discoverer, the
17th-century Dutch astronomer Christiaan Huygens.
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