THE HUYGENS MISSION - DESIGN APPROACH FOR AN ATMOSPHERE ENTRY PROBE

The ESA Huygens probe is part of the NASA/ESA Cassini mission to the Saturnian system, and will make a 2-2.5 h exploratory descent to the surface of Titan. Huygens is designed to enter and brake in Titan's atmosphere in order to parachute a fully instrumented robotic laboratory. The main scientific measurements will be performed during the parachute descent, but some will also be performed during atmospheric entry; in addition, the probe resources are sized to allow measurements after it has impacted Titan's surface for at least a few minutes. This paper describes the control design and optimisation of the Huygens mission, based on an open-loop concept which is one of the keys to minimizing the mission risks induced by the uncertainties in the external environment.