Cassini-Huygens is a joint NASA/ESA/ASI mission to explore Saturn, Titan and the other moons of the Saturnian system. The mission has two distinct elements: the Cassini orbiter and the Huygens probe.
The Cassini orbiter was built by NASA's Jet Propulsion Laboratory, with the Italian Space Agency (ASI) contributing its high-gain antenna and other radio subsystem equipment under a bilateral NASA/ASI agreement. Huygens, and the associated communications equipment on the orbiter, was built by ESA.
The Cassini-Huygens spacecraft was launched at
On 14 January 2005 the Huygens probe successfully entered Titan's upper atmosphere and descended under parachute to the surface. The descent phase lasted around 2 hours 27 minutes with a further 1 hour 10 minutes on the surface. Throughout the mission data were collected from all instruments providing a detailed picture of Titan's atmosphere and surface.
Cassini successfully completed its nominal mission in July 2008 after 75 orbits around Saturn and 44 targeted Titan flybys. During this nominal mission, scientific observations were focused on Saturn, the icy satellites, the ring system, Titan and the magnetosphere.
In July 2008 the first mission extension – known as the 'Cassini Equinox Mission' - began; this ran until October 2010. The Sun passed the equatorial plane on 11 August 2009. Cassini performed an additional 27 Titan flybys during the Equinox mission, and revisited, on seven occasions, Enceladus, an icy moon where active cryo-volcanism was discovered in Cassini data as early as 2005.
The current mission extension – called the 'Cassini Solstice Mission' – will run until the Saturnian Summer Solstice, when the Sun will reach its highest elevation on the northern hemisphere; this point will be reached in May 2017. During the Solstice mission Cassini will study seasonal effects in the Saturnian system and will continue flybys of two of the most intriguing moons of the system: Titan (56 flybys) and Enceladus (12 flybys). Different phases of the Solstice mission have been optimized for the study of Saturn's rings, the icy satellites, the magnetosphere and the atmosphere of Saturn.
In April 2017 the spacecraft will be injected into so-called 'proximal orbits' using a final gravitational pull from Titan. The periapsis of the last 23 orbits will be located in the narrow region between Saturn's D ring (the innermost ring of Saturn's main ring system) and Saturn's upper atmosphere. The mission will terminate in September 2017 when the spacecraft will plunge into Saturn's atmosphere.
The Huygens Probe was selected by ESA's Science Programme Committee in November 1988 as the first medium-size mission of the Horizon 2000 long-term scientific programme. NASA received approval for the start of Cassini in 1990.