Saturn's first probe to land 'with a thump or a squelch'

Space engineers sent Europe's Huygens probe sweeping towards Saturn's largest moon, Titan, on Saturday. Officials at the Jet Propulsion Laboratory in Pasadena, California, said they had received a signal confirming that the barbecue-sized robot craft had separated from its mother ship, the United States-built spaceship Cassini. Huygens, which is bristling with British-built instruments and detectors, will take 20 days to reach Titan, the only moon in the solar system with an atmosphere. Scientists believe conditions on Titan are similar to those on Earth before life evolved, billions of years ago. On 14 January, Huygens will enter Titan's thick atmosphere of nitrogen and methane and descend by parachute towards the moon's surface, relaying its data to Cassini above. Scientists do not know whether the craft will land on a solid, liquid or marshy surface. 'Huygens could land with a thump, a splash or a squelch,' said Professor John Zarnecki, leader of Britain's Huygens team. One scenario suggests that Titan -- whose surface temperature rarely rises above minus 180C -- may be covered with lakes, or even seas, of methane or ethane. The probe -- which spins seven times a minute to keep itself stable -- is electronically asleep and will only be awoken when on-board instruments detect the tug of Titan's gravitational field. The craft will have three or four hours to transmit to Cassini before its batteries run out of power. The mother ship will then relay Huygens' data to Earth.