Saturn's moon Titan is covered by "dirty" ice ridges and seas of liquid natural gas, a team of scientists said yesterday after a week of research into data from the space probe Huygens.
"We've got a flammable world," said Toby Owen, an atmospheric scientist, at a news conference from European Space Agency offices in Paris monitored on NASA TV.
After a seven-year piggyback trip from Earth on board the Saturn probe Cassini, the European-designed Huygens separated in December and fell towards Titan, entering the moon's atmosphere last Friday.
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.
Slowed by parachutes, Huygens took more than two hours to float to the icy surface, where it defied expectations of a quick death and continued to transmit for hours.
That surface, which scientists have said was the consistency of wet sand or even creme brulee, features ice rocks, channels, and abundant indications of liquid from rain.
"There's lots of evidence of fluid flow," said Marty Tomasko, the principal investigator for Huygens' on-board imaging instruments. While it does not rain every day on Titan, Ms Tomasko and colleagues speculated there must be some sort of regular precipitation on the surface.
The methane can exist in liquid form on Titan's surface because it is so cold, -179°C. Methane is also a key component in Titan's atmosphere, along with nitrogen. But as opposed to the Earth, the atmosphere of Titan lacks oxygen, which is essential to fire.
"There's no source of oxygen available, which is a good thing or Titan would have exploded a long time ago," Mr Owen said.
Though the mission teams collected just a few hours' worth of data, they expect to spend years analyzing it for clues as to how Titan formed, how it works and what it can say about the Earth's own development.
Titan is larger than the planet Mercury and, because of its atmosphere, a popular setting for science-fiction tales of human colonization and exploration.
And while manned missions are not necessarily on the horizon, researchers are already talking about what they might do next with Titan, if they had enough money to launch a mission that could probe the solid surface more actively.
"This is highly possible, we can now dream seriously of sending rovers to Titan," said Jean-Pierre Lebreton, the Huygens mission manager for the ESA.
Before that, though, the researchers - some of whom have worked on the project for the better part of two decades - will probably catch up on their rest.
"Some of the scientists did not sleep for days and nights, so we are a bit tired I must say," Mr Lebreton said.
The Cassini-Huygens mission to study Saturn's rings and moons was launched in 1997 and is named after two 17th century European astronomers: Christiaan Huygens, who discovered Saturn's rings and Titan, and Jean-Dominique Cassini, who discovered the planet's other four major moons.