Expected Results of HASI Experiment During Huygens Probe Descent on Titan in Cassini Mission

F. Ferri (C.I.S.A.S. Univ. Padova), M. Fulchignoni (DESPA-Obs Meudon/Univ. Paris), HASI Team

The launch of the Cassini-Huygens mission is foreseen for October 97. The mission aims to the exploration of the Saturnian system, with particular interest in Titan on which the Huygens probe will descent. The instrumentation onboard the probe will make measurements during the descent and after the landing, in order to investigate the nature of Titan.

Huygens Atmospheric Structure Instrument (HASI) is one of the six experiments composing the payload of Huygens. This experiment package has been proposed by an international collaboration including 17 institutions from 11 different countries. HASI has been designed to measure the physical quantities characterizing Titan environment, specifically to determine density, pressure and temperature profiles, to detect the presence of turbulence, wind and waves and to study the electrical properties of Titanšs atmosphere.

HASI will be operating since the Probe entry in Titan atmosphere. In this phase, information about density, pressure and temperature conditions will be derived indirectly from the deceleration measurements of HASI three-axes accelerometer. After the Probe frontal thermal shield release, direct measurements of pressure, temperature and electrical properties will be performed throughout Titan stratophere and troposphere, till the Probe landing and after that.

Providing the unique pressure and temperature information during the Huygens probe entry and descent in Titan atmosphere, HASI will contribute to the investigation of atmospheric composition and structure. Its data will also supply information on surface, whatever its phase: liquid or solid.