The Huygens Atmosphere Structure Instrument (HASI) comprises sensors for measuring the physical and electrical properties of the atmosphere and an on-board microphone to send back sounds from Titan
On 14 January 2005, astronomers around the world were holding their breath.
The Huygens probe was about to enter Titan's atmosphere and land on its surface.
The Cassini-Huygens mission to Saturn is an extremely ambitious effort in planetary space exploration.
A joint endeavour of the European Space Agency (ESA), NASA and the Italian space agency (ASI), Cassini-Huygens sent a robotic spacecraft to orbit and study the Saturnian system in detail over a four-year period.
On board Cassini was a probe called Huygens that was released on 25 December 2004 from the main spacecraft.
Huygens's mission was to parachute through the atmosphere to the surface of Saturn's largest and perhaps most interesting moon, Titan.
The Huygens Atmosphere Structure Instrument (HASI) comprises sensors for measuring the physical and electrical properties of the atmosphere and an on-board microphone to send back sounds from Titan.
There is also a series of Vaisala Barocap sensors, ie, capacitive absolute pressure sensors manufactured by silicon micro-machining.
The Barocap sensor has excellent hysteresis and repeatability characteristics, as well as outstanding temperature and long-term stability - features certainly required in Titan's thick nitrogen atmosphere and cold surface (-180C).
Huygens' descent and landing were successful.
The data and stunning images collected will keep scientists busy for months if not years to come.
