Titan probe sends back evidence of methane rainfall

AFP , PARIS

Sun, Jan 23, 2005 - Page 6

The European robot lab Huygens found liquid methane on the Saturn satellite Titan, a chemical that seems to have shaped the moon's peculiar landscape and weather system, scientists said Friday in their first detailed assessment of the probe's mission.

"We've got a flammable world. It's quite extraordinary," said University of Honolulu researcher Toby Owen, referring to methane's combustibility with air on Earth.

"There is liquid on Titan. It has been raining not long ago, there is liquid methane," said Jean-Pierre Lebreton, director of the Huygens mission at the European Space Agency (ESA).

"There are truly remarkable processes at work on Titan's surface," he said.

US researcher Marty Tomasko of the University of Arizona said the data sent back by Huygens showed "many familiar earthlike processes: abrasion, erosion, precipitation."

"On the place where we landed, it had been raining not long ago, maybe two days ago," Tomasko said at a presentation to the press at ESA headquarters in Paris.

The rain -- not water but liquid methane, which is toxic to humans -- causes soil to run down from the hills and forms the rivulets and gullies that were visible in the raw images of Titan, shown to the world last week.

Huygens, a 319kg craft fitted with cameras, atmospheric sensors and gas analyzers, landed on Titan on Jan. 14, sending back data to a US mothership, Cassini.

Titan, the largest satellite of Saturn, was chosen as, intriguingly, it is the only moon in the solar system that has a substantial atmosphere.

Its thick mix of nitrogen and methane is suspected to be undergoing chemical reactions similar to those that unfolded on Earth billions of years ago. That process eventually provided the conditions for life on our planet.