November 30, 2005

Life on Saturn’s moon Titan unlikely: experts

By Paul Carrel

PARIS (Reuters) - Saturn's moon Titan resembles Earth in
many ways but is unlikely to support life, scientists said on
Wednesday after almost a year of research into data from the
space probe Huygens.

After a seven-year trip from Earth piggy-backed on the
Saturn probe Cassini, the European-designed Huygens separated
last December and headed for Titan, entering the moon's
atmosphere in January this year.

"Huygens descended through a hazy, windy and turbulent
atmosphere," Jean-Pierre Lebreton, Huygens mission scientist at
the European Space Agency, told a news conference in Paris.

"This revealed an extraordinary world which resembled the
Earth in many respects -- but there are also clear
differences," he said. "The laws of physics, the laws of
chemistry are the same. The ingredients are different."

The probe, part of a $3 billion joint mission involving
NASA and the European and Italian space agencies, sent back
readings on the moon's atmosphere, composition and landscape.

The readings showed Titan was cold and windy with a dense
atmosphere packed with nitrogen and methane, and which showed
evidence of possible lightning. It has been described as "a
flammable world" by one scientist involved in the project.

Titan is larger than the planet Mercury and, because of its
atmosphere, is a popular setting for science-fiction tales of
human colonization and exploration. Unlike Earth, however, its
atmosphere lacks oxygen.

It has a largely flat surface with a texture like wet clay,
but also features ice rocks. Its surface temperature is about
minus 180 Celsius, and the cold probably allows methane rain to
fall, the scientists said.

Francois Raulin, another of the experts involved in the
project, said analysis of data from Huygens showed it was
unlikely Titan could support life.

"If there is or if there was life on Titan, the best place
would be in the interior," he said. "Water is a prerequisite
for life but liquid water, not ice. There is no liquid water on
the surface because it's too cold."

He added: "The only chance of having permanent liquid water
on Titan is inside."

The Cassini-Huygens mission to study Saturn's rings and
moons was launched in 1997 and is named after two 17th-century
Europeans: Dutchman Christiaan Huygens, who discovered Saturn's
rings and Titan, and Italian-French astronomer Jean-Dominique
Cassini, who discovered the planet's other four major moons.