Huygens (spacecraft) - Findings

Findings

Early imaging of Titan from the Cassini mission was consistent with the presence of large bodies of liquid on the surface. The photos showed what appeared to be large drainage channels crossing the lighter coloured mainland into a dark sea. Some of the photos suggested islands and mist shrouded coastline. 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 left. Mission scientists also reported a first "descent profile", which describes the trajectory the probe took during its descent.

Subsequent work done on the probe's trajectory indicated that, in fact, it landed within the dark 'sea' region in the photos. Photos of a dry landscape from the surface suggested that while there was evidence of liquid acting on the surface recently, hydrocarbon lakes and/or seas might not be present on Titan. Further data from the Cassini Mission, however, definitely confirmed the existence of liquid hydrocarbon lakes in the polar regions of Titan (see Lakes of Titan).

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 colour of Titan's surface to a crème brûlée, but admitted this term probably would not appear in the published papers.

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.

Thermometers indicated that heat was wicked away from Huygens so quickly that the ground must have been damp, and one image shows light reflected by a dewdrop as it falls across the camera's field of view. On Titan, the feeble sunlight allows only about one centimeter of evaporation per year (versus one meter of water on Earth), but the atmosphere can hold the equivalent of about 10 meters of liquid before rain forms vs. only a few centimeters on Earth. So Titan's weather is expected to feature torrential downpours causing flash floods, interspersed by decades or centuries of drought.