Jon Clarke over at Space.com's message board has posted information he gathered from last month's EGU conference in Vienna. Being only a little over a month since the LPSC conference in Houston, I wasn't expecting many new results but there are a few really interesting tidbits:
- From Huygens, the highlands are brighter and redder than the lowlands. From the surface images, we know that the low lands are covered in pebbles, 8-10 cm in size. Based on calculations, it was determined that methane fluvial flows moving at 1 m/second would be required to transport clasts of that size. We know from LPSC that the highlands are between 100 and 200 meters higher in altitude than the lowlands. From EGU, we now know from the Sonar instrument that there are two distinct levels within the highlands, one 8 meters taller than the other. This higher level might consist of small mesas surrounded by lower level material.
- A talk by Raulin et al. discussed the implications of the discovery of higher order C-N compounds with up to 7 carbons (found by INMS last month). They suggest that these are the tholins predicted by Sagan et al. In addition, they believe that based on the overall atmospheric abundance, the most abundant liquid phase on the surface is ethane.
- In the VIMS talks on Iapetus, they note that the ices in Cassini Regio include CO2 and C-N (as noted last month, this result is similar to that of Phoebe, except very little water ice was found in Cassini Regio). In terms of the origin of Cassini Regio, the speakers at the conference seemed to shy away from an external origin, due to the distribution of the dark material not being hemispherical, and from a cyrovolcanic origin due to the diffuse nature of the transition zone. The authors note that that Cassini Regio is symmetric north-south from the ridge. One author even went so far as to suggest that Cassini Regio originated from geysers along the ridge. While I admit that I once posited that myself, the apparent rigidity of the crust, the ancient age of the ridge from the number of crater on it, the apparent youthful age of the dark material, argues against this hypothesis. Personally, I like the idea suggested at LPSC that the dark material isn't so much the emplacement of dark material, but the striping off of bright material, that the almost total absence of water ice in Cassini Regio suggests that it was removed somehow, leaving behind a dark, fluffy, lag deposit.
I want to thank imran at the Unmannedspaceflight.com
forum for the heads-up on this.