November 30, 2005

Life on Saturn’s Moon Titan Unlikely

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.