Probe to float into a fog of mystery

National Astronomy Meeting: Scientists hope to unravel one of the great riddles of the universe

Scientists yesterday unveiled detailed plans to land the first probe on the surface of the largest of Saturn's moons Titan, swathed in clouds of orange fog.

Astronomers hope the probe, codenamed Huygens, will provide the first information about Titan. Scientists at the United Kingdom National Astronomy meeting in Liverpool were told that the probe, to be launched from the Cassini satellite on its mission to orbit Saturn, could help unravel "one of the great mysteries of the solar system".

Dr John Zarnecki, professor of physics at the University of Kent, told the conference the probe could be heading for a splashdown. "Little is known about the surface of Titan because of the thick orange clouds that surround it," he said afterwards. "We don't know if we will be touching down on liquid, solid or gunge."

Dr Zarnecki, who is heading a 25-strong international team to conduct one of the six experiments on board the Huygens, said Titan's atmosphere was similar to that of the Earth approximately 4.5 billion years ago. "It is nitrogen dominated, containing a mixture of hydrocarbons and has a temperature of minus 180C," he said.

"But though the Voyager satellite passed by Titan in the 1980s, it was unable to see what the surface is like because of the clouds that make up its atmosphere.

"We hope this mission will give us another piece of the jigsaw in our understanding of the origins of our Solar System. It could unravel one of the great mysteries of the universe."

The Cassini orbiter built by Nasa is due to take-off from the United States in October next year. The Huygens probe, developed by the European Space Agency, has been built with a "flying saucer-like" hull to enable it to land on Titan's potentially liquid surface, Dr Zarnecki said. It will be equipped with a floodlit camera to penetrate Titan's dense atmosphere and hopefully take the first pictures of the moon's surface.

The satellite will take seven and a half years to travel the 600 million miles to Titan. But once there the Huygens will have only 30 minutes to gather information about the surface before its batteries run out. The probe, measuring six feet across, will "float" towards Titan using a British designed parachute. Dr Zarnecki's experiment to determine the temperature, density and electrical properties of the surface called the Surface Science Package, has been designed and manufactured in the UK over the past six years. It is hoped the Huygens will descend on Titan in 2005.

Information from the probe will be beamed back to the orbiting satellite and then relayed for analysis to scientists on Earth.