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 jettiso