The Huygens probe, supplied by the European Space Agency (ESA) and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry probe and lander carried to Saturn's moon Titan as part of the Cassini-Huygens mission. The combined Cassini-Huygens spacecraft was launched from Earth on October 15, 1997. Huygens separated from the Cassini orbiter on December 25, 2004, and landed on Titan on January 14, 2005 near the Xanadu region. It touched down on land, although the possibility that it would touch down in an ocean was also taken into account in its design. The probe continued to send data for about 90 minutes after reaching the surface.
Preliminary findings seemed to confirm the presence of large bodies of liquid on the surface of Titan. The photos showed what appear to be large drainage channels crossing the lighter colored mainland into a dark sea. Some of the photos even seem to suggest islands and mist shrouded coastline.
At the landing site there were indications of chunks of water ice scattered over an orange surface, the majority of which is covered by a thin haze of methane. The instruments revealed "a dense cloud or thick haze approximately 18-20 kilometers from the surface". The surface itself was reported to be a clay-like "material which might have a thin crust followed by a region of relative uniform consistency." One ESA scientist compared the texture and color of Titan's surface to a Crème brûlée, but admitted this term probably would not appear in the published papers.
On January 18 it was reported that Huygens landed in "Titanian mud", and the landing site was estimated to lie within the white circle on the picture to the right. Mission scientists also reported a first "descent profile", which describes the trajectory the probe took during its descent.
However, subsequent analysis of the data suggests that surface consistency readings were likely caused by Huygens displacing a large pebble as it landed, and that the surface is better described as a 'sand' made of ice grains. The images taken after the probe's landing show a flat plain covered in pebbles. The pebbles, which may be made of water ice, are somewhat rounded, which may indicate the action of fluids on them.
Further work done on the probe's trajectory indicate that in fact it landed within the dark 'sea' region in the photos. Photos of a dry landscape from the surface contradict the original theory that the dark regions were liquid seas, leading researchers to conclude that while there was evidence of liquid acting on the surface recently, the much anticipated hydrocarbon seas of Titan were in fact absent. Wikipedia
