ESA's Huygens Probe was delivered to Titan by the Cassini Orbiter in January 2005 after a dormant interplanetary journey of 6.7 years - although Huygens was activated every six months for health checks.
The probe started its descent through Titan's hazy cloud layers from an altitude of about 1270 km. During the following three minutes Huygens had to decelerate from 18 000 to 1400 km per hour. A sequence of parachutes then slowed it down to less than 300 km per hour. At a height of about 160 km the probe's scientific instruments were exposed to Titan's atmosphere, and at about 120 km the main parachute was replaced by a smaller one to complete the 2.25-hour descent.
Built by an industrial consortium led by Aerospatiale, the Probe System comprises two principal elements:
The Probe itself consists of the Entry Assembly (ENA) cocooning the Descent Module (DM). The ENA provided Orbiter attachment, umbilical separation and ejection, cruise and entry thermal protection, and entry deceleration control. It was jettisoned after entry, releasing the Descent Module.
The DM comprises an aluminium shell and inner structure containing all the experiments and Probe support subsystems, including the parachute descent and spin control devices.
The Probe Support Equipment (PSE) consists of: