The joint NASA-ESA Cassini-Huygens mission to Saturn is the most ambitious planetary mission since the VEGA mission to Venus and Halley in 1985/86 and the Viking arbiters and landers to Mars in 1976. Perhaps Cassini is even more ambitious than these earlier missions, or at least more daring, as it is being attempted as a single launch unlike early missions such as VEGA, Viking and Voyager that benefited from the security of a redundant spacecraft. This volume describes the mission, the orbiter spacecraft, the Titan atmospheric probe and the mission design in articles written by its project scientists and engineering team. These are followed by five articles from each of the discipline working groups discussing the existing knowledge of the Saturnian system and their goals for the mission. Finally, each of the Huygens entry probe instrument teams describes their instruments and measurement objectives. These instruments include an atmospheric structure instrument, an aerosol pyrolyser, an imager/radiometer, a gas chromatograph, a surface science package and a radio science investigation.