[X] My Assistant

[volcanopele]

Much to my surprise, a chunk of the T16 Sar swath as been released:

http://photojournal.jpl.nasa.gov/catalog/PIA08630

An abundance of lakes can been seen. Some appear to be crater lakes (or sinkholes), like the lake at far left on the top cutout. That lake appears similar to Crater Lake in Oregon, with a little island in the middle (you can kinda see the attenuation of the signal surrounding the island as the methane gets deeper). Some lakes appear quite distinctive from the surrounding terrain, like the features on the right part of the bottom cutout.

[Thorsten]

I’m a little puzzled by the latest News Release on the T16 RADAR swath:

http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=679

Cassini scientist are now quite confident that at least some of the radar dark spots are indeed lakes (which is great!). They further state that “the lakes are most likely the source of hydrocarbon smog in the frigid moon's atmosphere”.

I thought that the hydrocarbon smog was generally hypothesized to originiate from organic molecules formed by photodissociation of methane in Titan’s upper atmosphere. So do they presume that the hydrocarbon smog comes indirectly from methane evaporating from the polar lakes and thus replenishing Titan's methane atmosphere?
Are these comparatively small lakes really sufficient to replenish the atmospheric methane? At the northern hemisphere, they seem to be quite restricted the latitudes above 75 degrees. Furthermore, some of these “lakes” appear to be only partly wet at the moment and probably do not harbor large quantities of liquid methane.
Isn’t it still more likely that methane from Titan’s interior (released by cryovolcanoes, low temperature serpentinization, whatever) prevents the atmospheric methane depletion? At least, there is some circumstantial evidence for volcanic activity, like the detection of 40Ar by Huygens’ GCMS.

[ugordan]

I’m a little puzzled by the latest News Release on the T16 RADAR swath:

http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=679

Cassini scientist are now quite confident that at least some of the radar dark spots are indeed lakes (which is great!). They further state that “the lakes are most likely the source of hydrocarbon smog in the frigid moon's atmosphere”.

That statement caught my eye, too. I think that's stretching it a bit. The lakes contain methane which in turn evaporates into the atmosphere where it's broken down by UV light to produce smog. So technically, they are the source of the smog (not a direct source, though!). The wording is a bit awkward.

I agree with you on the point of lakes being just a temporary reservoir of methane, cryovolcanism is probably the mechanism by which Titan's methane is replenished. Without it, the lakes would eventually all dry up because all methane would be destroyed on a fairly short timescale.
That is, unless there's actually a vast reservoir of methane hiding below the surface. The question would then be: where'd THAT come from?