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Following the Cassini-Huygens space probe to Saturn
Thursday 6 January 2005, 9.00 - 9.30pm

Cassini-Huygens, a US/European space probe the size of a bus, reached Saturn in July after a seven year journey around the Solar System. The probe is packed with scientific apparatus to measure every vital statistic of the planet, its 33 moons and its famous rings. Richard Hollingham investigates this 'Lord of the Rings' and the possibility that one of the moons, Titan, could be a colder version of the Earth and thereby a potential future home for humans.

Cassini-Huygens artist's view (NASA/JPL)
An artist's impression of Cassini-Huygens (NASA/JPL)

Saturn is perhaps the most beautiful but also the most mysterious of planets.

The biggest mysteries of all concern its wonderful rings and its cloudy moon, Titan.

Cassini, the most ambitious unmanned space probe ever, is now orbiting Saturn, seeking answers to those mysteries and raising new questions as it goes.

Its passenger, the European probe Huygens, is heading for Titan, and, all being well, should parachute down through the butterscotch clouds on January 14th to become the first craft to land on this alien world.

Listen again Listen again to the programme
Huygens Saturn (ESA)
Artist's impression of Saturn, as seen from Titan, with Cassini just visible (ESA) 

The Cassini-Huygens mission is the fourth space craft to visit the planet - Pioneer 11 and Voyager 1 and 2 passed by briefly - but this is the first to go into orbit and the first to send a probe onto one of its moons.

This mission will spend at least four years studying the Saturnian system.

It's been a huge international collaboration between the American and the European space agencies and university researchers.

This programme tells the story of the mission, the launch and the journey to the planet, the first results now that it has arrived and in particular, the prospects for Huygens as it attempts to land on the moon Titan on January 14th.
Titan Weather (NASA/JPL/University of Arizona)
Titan's weather (NASA/JPL/University of Arizona)

On Christmas day 2004 the Huygens probe was released from the side of Cassini.

As our programme is broadcast, it is speeding towards Titan at nearly six kilometres per second (1300 MPH). It arrives at the top of Titan's thick atmosphere at about 09:30 GMT on January 14th.

But will it land with a crash or a splash?

No one knows what Huygens will hit when it lands - it could be rock-hard ice, a sticky gunge of organic chemicals or a lake of liquid petroleum such as ethane.

And if Titan has life today it has to be very unlike anything we know:  the temperature is 180 degrees below freezing.

But its potential for life may be realised in a few billion years time, as the Sun expands and makes the Earth uninhabitable.

Perhaps then this strange moon will become the human home.

Listen again Extended Interview: Chris McKay 15'44"

Listen again Extended Interview: Carl Murray 29'00"

Listen again Extended Interview: John Zarnecki 14'36"
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