Titan lakes

If water acted like benzene, lakes would freeze from the bottom up and become solid ice. In a benzene world, fish could not survive in colder climates. Icebergs would be at the bottom of the sea, and the Titanic might still be afloat. The world as we know it would be topsyturvy if water behaved like benzene. That leads to the question Why doesn t it ... 

Studies carried out on Earth, for example, by the NASA infrared telescope on Mauna Kea (Hawaii), showed albedo variations which indicated the presence of holes in the Titanian cloud formations (Griffith, 1993). It is, however, still unclear as to whether these inhomogeneities result from differences in the surface composition. Lorenz et al. (1997) reported large variations in Titan s atmosphere due to photochemical processes. The methane contained in the dense nitrogen atmosphere is decomposed by solar and thermal radiation, and its content may be replenished from methane lakes or from clathrates. 

G. Mitri and co-workers calculated the minimum area of hydrocarbon lakes which would be necessary to preserve the relative methane humidity in the lower regions of the atmosphere. The result was surprising the calculations indicated that only between 0.002 and 0.2% of the total surface area of Titan would be required (Mitri et al., 2007). 

One of the most commonly used colorimetric methods is based on the adsorption of a dye by magnesium hydroxide to form a colored lake in alkali hydroxide solution. Titan yellow [methylbenzothiazole-(l, 3)-4,4 -diazominobenzene-(2,2 )-disulfonic acid] is the most widely used dye [97]. Typically, the sample is pretreated by incineration or acid extraction. Iron, aluminum, manganese, copper, zinc, nickel, and phosphorus must be removed from the sample due to interference of these elements with the color formation [97]. 

The Cassini spacecraft successfully landed a small probe on tbe surface of Saturn s moon Titan in 2005. The probe discovered features that resemble lakes, rivers, and shorelines on Earth, but on Titan, they were formed by liquid methane instead of water. 

On Titan, sand-like grains heap up in dunes like a subzero Sahara (no one knows what they are). Some kind of lava flows darken the landscape (no one knows what they are, either). Hard to see, but perhaps most amazing, are the lakes and rivers of liquid methane pooling and flowing over the surface. The pictures could have been taken from your last lakeshore vacation—if you had an orange filter on the whole time and only took pictures of rocks. 

So life on Titan could move in the methane lakes and eat acetylene and other hydrocarbons as food. We can t see microbes from this distance, but we should be able to see their food in the atmosphere. In particular, scientists looked for the small hydrocarbons acetylene and ethene on Titan, as well as the hydrogen needed to burn them. But they couldn t find either—simulations have come up empty. The tastiest molecules for life are conspicuously absent. 

Radar images obtained on July 21, 2006 appear to show lakes of liquid hydrocarbon (such as methane and ethane) in Titan s northern latitudes. This is the first discovery of currently-existing lakes anywhere besides Earth. The lakes range in size from about a kilometer to one which is one hundred kilometers across. Hydrocarbon seas on Titan s surface up to a size of 500 000 km are described by Turtle... 

Fig. 4.9 The Cassini spacecraft, using its radar system, has discovered very strong evidence for hydrocarbon lakes on Titan. Dark patches, which resemble terrestrial lakes, seem to be sprinkled all over the high latitudes surrounding Titan s north pole. NASA/JPL/Space Science Institute...

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