The scientific objectives of the Cassini/Huygens mission to Titan are to:
- determine atmospheric composition;
- investigate energy sources for atmospheric chemistry;
- study aerosol properties and clouds physics;
- measure winds and global temperatures;
- determine properties of the surface and infer internal structure;
- investigate the upper atmosphere and ionosphere.
More information can be found in the SP-1177 paper: The Huygens Probe: Science, Payload and Mission Overview (Lebreton and Matson), 1997.
Complementary information regarding the science objectives at Titan may be found on the JPL Cassini web page.