The Cassini Launch

ESA's Huygens Probe is now on its seven-year journey to Saturn's moon Titan, aboard NASA's Cassini spacecraft. The joint NASA/ESA mission was successfully launched by a Titan IVB/Centaur launch vehicle on 15 October 1997 04:43 EDT. It will reach Saturn in 2004.

While the Cassini Orbiter continues to explore Saturn and its rings, the Huygens probe will be released to parachute through the atmosphere of Titan. Shrouded in an orange haze that hides its surface, Titan is one of the most mysterious objects in our solar system. It is the second largest moon (only Jupiter's Ganymede is bigger), and the only one with a thick atmosphere. It is this atmosphere that excites scientific interest, since it is thought to resemble that of a very young Earth.

The large (5.82 tonne) Cassini/Huygens spacecraft needs help to reach distant Saturn, gaining momentum through a series of gravity-assist manoeuvres.

The first significant scientific event of the joint mission begins in November 2004 when, towards the end of Cassini's first orbit around the ringed planet, the Huygens Probe is ejected towards Titan.

At the end of a 22-day cruise to Titan, the Probe will plunge through the atmosphere at 20,000 km/h, taking from 2 to 2½ hours to reach Titan's surface. A heat shield protects it from temperatures of more than 12,000 degrees and acts as a brake. As it slows to 1400 km/h a series of parachutes will be deployed to provide a controlled descent and a stable platform for scientific measurements.

Huygens' six instruments will take measurements throughout its spectacular descent, providing details on the chemical composition of Titan's atmosphere, its weather and clouds, and then the surface itself. Spectacular data and images are already expected from the descent itself and, if the Huygens Probe survives the impact with the mysterious surface, it will continue to send unique information back to the mother ship until its batteries expire or the Cassini Orbiter is out of range.

Preserved in the deep freeze of Titan's atmosphere are chemical compounds thought to be similar to those of Earth's primeval soup. The in-situ results from Huygens, combined with Cassini's global observations from repeated flybys of Titan, will provide vital information towards the great mystery of how life began on Earth.

Prof. Manuel Grande
Last updated: 1 July 2004