Scientists were celebrating tonight after confirmation that a European spacecraft had landed safely on Saturn's icy cloud-covered moon Titan after a seven-year journey.
The Huygens probe parachuted through Titan's thick, smoggy atmosphere to reach the surface at about 11.30 a.m. It continued transmitting signals for hours afterwards, indicating that it had weathered the descent and survived the landing.
Scientists believe the nine foot wide craft has come to rest on a stable, relatively hard surface. There was speculation that it might have sunk into tarry sludge or splashed into a lake or sea of liquid lighter fuel, in which case the probe was not expected to last long.
Experts are now anxiously waiting for the first images taken by Huygens' panoramic camera. They are expected to reveal a truly alien world. Titan, bigger than the planet Mercury, is the only moon in the Solar System with its own atmosphere, made of a smoggy blanket of nitrogen, methane and ammonia.
The surface is thought to consist of frozen methane and ethane, but may have steep mountains, craters, volcanoes and even lakes and seas. In many ways Titan resembles the earth before the birth of life four billion years ago.
Scientists believe it will act as the perfect laboratory for studying the early earth. Finding earth-type life on Titan is extremely unlikely with temperatures of minus 180 Celsius.
However, one group of scientists claims conditions on the moon could support specially adapted life forms. Huygens was carried to Saturn by Nasa's Cassini spacecraft on an epic two billion mile journey.
It separated from its mothership on Christmas Day and navigated itself to Titan using autonomous guidance systems developed in Britain. The first indication that Huygens had landed came from a carrier signal transmitted from the probe and picked up by radio telescopes on earth.