THE SURFACE OF TITAN IN THE CONTEXT OF ESA HUYGENS PROBE

The ESA Huygens Probe is scheduled for launch as part of the NASA/ESA Cassini mission to the Saturnian system in 1997, due to arrive at Tita n in late 2004, to make a 2.25 h exploratory descent to the surface. H owever, the state of Titan's surface is completely unknown and the moo n may be at least partially covered in liquid hydrocarbons. This paper reviews the current theories and observations relating to Titan's sur face and suggests that a heterogenous surface composed of ice and orga nic compounds (some of them liquids, accumulating in seas and lakes) i s the most plausible. Geological and meteorological processes that may be occurring on Titan are considered from a comparative planetologica l viewpoint, in order to make predictions about features that may exis t on Titan's surface. Several 'model' surfaces are presented for the f uture estimation of the Huygens Probe's survivability on the Titan sur face.