Scientists have issued a weather forecast for the oily oceans of Titan, Saturn's major moon and a target for a space probe landing next year.
By Dr David Whitehouse
BBC News Online science editor
Researchers gathered at the UK National Astronomy Meeting have calculated how the moon's seas compare with Earth's.
Waves would be seven times higher than Earth waves but would move more slowly and be much farther apart, they think.
In January 2005, we may find out if this is correct when the Huygens probe attempts a splashdown on Titan.
Down to a sunless sea
The European probe is being carried to the Saturnian system by the US Cassini spacecraft.
Huygens will parachute down through the smoggy atmosphere of Titan, but astronomers are unsure of what it will find.
It may come down into an ocean of hydrocarbons or on to a frozen sheet of ice.
TITAN - MOON OF SATURN
Second largest moon in the Solar System; only Ganymede is larger
Only moon in the Solar System with a thick atmosphere
Keeps its same face toward Saturn as it orbits the planet
Lakes of liquid ethane and methane may cover moon's surface
If it is an ocean, then scientists want to know what to expect, so a team from the Open University, Surrey Satellite Technology and the Southampton Oceanography Centre have developed a computer simulation to predict how wind-driven waves on the moon would behave.
Ever since the first flyby of Titan, by the Voyager 1 spacecraft in 1980, scientists have thought its surface could be covered by seas of ethane or methane.
Radar signals bounced off the moon have reinforced this idea of oily oceans. Researchers using the giant Arecibo radio telescope have analysed echoes from Titan and concluded that up to 75% of the moon's surface could be covered by open bodies of liquid hydrocarbons.
The exact nature of the reflected signal can be used to determine the choppiness of the liquid mass. The indications are that the slope of the waves is typically less than four degrees - a figure with which the recent simulations agree.
"Hopefully the European Space Agency's Huygens probe will end the speculation," said Dr Nadeem Ghafoor, of Surrey Satellite Technology.
"Not only will this be by far the most remote soft-landing of a spacecraft ever attempted but Huygens might become the first extraterrestrial boat to sail on a hydrocarbon sea."