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TITAN

Radar imagery of Titan has identified numerous cryovolcanic flows, fluvial features, tectonic features and a very small number of craters. The cryovolcanic flows are leveed, and the fluvial features debouche onto lowland fans and deltas

The Huygens descent imaging has been processed, resulting in better images, although rectification is proving a slow job. The highlands are significantly brighter and redder than the lowlands, which were called lake beds by several speakers. The presence of episodic methane fluvial activity was also well accepted. Theoretical modeling of methane-ethane liquids and their ability to transport clasts of the 8-10 cm size seen at the landing site under Titan gravity has been carried out. The results indicate that flow velocities of 1 m per second are required, which are quite reasonable. The atmospheric sonar indicated that the highland areas consist of two distinct levels, this might consist of small buttes or mesas over a lower surface. There is about 8 m difference in elevation between the two.

There was an interesting review of the astrobiological implications of the discoveries on Titan by Raulin et al. The main implications discussed were planetary organic geochemistry, the origin of terrestrial life, and the search for extraterrestrial life. Some of the major points I noted was that there is a high probability of a subsurface water-ammonia ocean. Carbon isotope ratios measured were all in the inorganic range, as expected. High molecular weight C-N compounds were detected, with up to 7 carbon atoms, these are the tholins predicted by Sagan many years ago. It is worth noting that the formation of tholins by inorganic processes can cause significant fractionation of light carbon into what is normally considered the biological range. As predicted theoretically, the tholins seem to be scavenged by methane range and transported to the surface. Overall atmospheric abundances indicate that the predominant surface liquid phase is likely to be ethane.

IAPETUS

Organics are concentrated near the equator, ice at the poles. The ices include CO2 and CN compounds. The regolith is very porous, with a low thermal inertia. The dark material on Iapetus is not hemispherical, therefore is not of external origin. The boundaries are diffuse, and therefore not cryovolcanic. One author suggested that they are geysers deposits, similar to what has been seen on Triton. They may be linked to the equatorial ridge, which does not continue right round the moon. The dark material seems to be symmetrically distributed north and south of the ridge, suggesting a link.

Has anyone here attended the European Geoscience Union conference in Vienna?  Jon Clarke, a geologist who posts regularly at Space.com, posted a summary of some of the interesting papers that were presented there.  Here he talks about Titan and Iapetus.