The Cassini/Huygens Mission Current models for Titan's atmosphere and surface will soon be tested in detail. This will happen in 2004 by the instruments on-board the NASA/ESA Cassini mission. It is the result of a 10-year collaboration between NASA and the European Space Agency. The two institutions decided in 1987 to dedicate to Titan an entire space mission that was named Cassini/Huygens. Giovanni Cassini discovered the gap in Saturn's rings in 1676. And the Huygens module will arrive on Titan, very nearly 350 years after Christiaan Huygens discovered Titan in 1655! The orbiter and the descent module The target of the Cassini/Huygens mission is the system of Saturn, with its 18 satellites and seven rings. The spacecraft is composed of an orbiter (Cassini) that will stay in orbit around Saturn from 2004 on and will return data for at least four years. Its other purpose is to deliver into Titan's atmosphere the descent module, Huygens, for a two and a half hour descent. Cassini carries 12 instruments, among which are spectrometers, radar and cameras, while Huygens has a mass of 319 kg, is 2.5 m across, with six experimental instruments on board that will penetrate the atmosphere of Titan and make precise measurements of its density, pressure and temperature in the lower 170 km. The launch The Cassini spacecraft was successfully launched at 4:53 a.m. on the morning of 15 October 1997 from the Kennedy Space Centre at Cape Canaveral (Florida). This mission is an extraordinary achievement of scientific and technological breakthroughs resulting from a fruitful collaboration between the US and 17 European countries. The launch was a great success. A roar marked the ignition and a huge flame burnt the ground around the spacecraft, as it launched towards the sky. At a height of about 16 km, the rocket boosters were ejected, and the spacecraft, crossed the night sky like a bright comet , starting on its seven-year course towards Saturn. The measurements showed that the launch, as well as the adopted course, was performed with great accuracy and according to schedule. The rocket, used for the launch of the Cassini mission, had coincidentally the name "Titan IV/Centaur". So Cassini was set on its way to Titan by... Titan! Current status Cassini is now well advanced on its course to Saturn (you may check where it is now), with planned arrival in July 2004. The Cassini orbiter has already returned data about Venus, Jupiter and the Earth, when the spacecraft passed by these planets en route. Everything is functioning well. Work for generations! Cassini will provide ten times more information than the Voyager missions. Voyager data are still being analysed, today, 20 years after the encounter, by many current and future astronomers. Can you then imagine how long it will take to fully reduce and interpret the large amounts of Cassini images and spectra? It is safe to predict that scientists of the coming generations will be busy with them, well into the 22nd century.

The launch of Cassini Schematic view of the Cassini spacecraft, with the various instruments indicated (NASA). The most crucial mission phase will be the descent of the ESA Huygens probe through Titan's atmosphere. The batteries and all other resources are sized for a duration of 153 minutes, corresponding to a maximum descent time of 2.5 hours plus at least 3 additional minutes (and possibly a half hour or more) on Titan's surface (ESA).