[X] My Assistant

[remcook]

Paper out tomorrow: http://www.bbc.co.uk/news/science-environment-25849871
Very exciting that we will visit this world soon!

[mcgyver]

Recent paper:
"THE POTENTIAL FOR VOLCANISM ON CERES DUE TO CRUSTAL THICKENING AND PRESSURIZATION OF A SUBSURFACE OCEAN."
http://www.hou.usra.edu/meetings/lpsc2015/pdf/2831.pdf

interior evolution models for Ceres [e.g. 2-5] suggest that differentiation is likely, forming a layered structure with a rocky interior (possibly with a separated iron core), overlain by water and ice layers. Furthermore, these models suggest that there is sufficient heat available that a liquid water layer could survive under an icy exterior to the present day.

I can't yet understand where this heat come from. Does "[e.g. 2-5]" mean "references from [2] to [5]"?.

Because ice takes up a larger volume than the equivalent mass of water, the freezing of liquid water onto the base of an icy shell will cause the shell to expand slightly and lead to tensile stress in the shell.
This also has the effect of increasing the pressure in the ocean, possibly to the point of driving liquid to the surface.

So the model suggests NOT that there's enough heating to create a water geyser (as I supposed), but there's a "squeezing" of the ocean by the ice crust.

For Ceres (r= 475 km), which is intermediate in size between those bodies, we assume as our initial condition that the rocky core is ~300 km in radius with an overlying ocean and an icy shell 25 km thick. This corresponds to the state of Ceres 500 Myr after its formation in the models of [5]. In the models of [5], the shell thickens over the subsequent 4 Gyr at an approximately linear rate of ~20 km/Gyr.

cracks can propagate to at least 200 km depth, which is about the maximum possible thickness of an ice shell for Ceres.

for every 1 km of thickening of the shell, approximately 25 m of liquid could erupt over the entire surface

but beware of

The requirement that the ice layer behave like an intact, elastic shell could pose a problem, especially in the case where the tensile strength of ice is exceeded well before the ocean pressure is sufficient to drive material to the surface.

[John Broughton]

Recent paper:
"THE POTENTIAL FOR VOLCANISM ON CERES DUE TO CRUSTAL THICKENING AND PRESSURIZATION OF A SUBSURFACE OCEAN."
http://www.hou.usra.edu/meetings/lpsc2015/pdf/2831.pdf

Coincidence or not, that paper appears to have been released on March 1, more than two weeks ahead of next week's Lunar and Planetary Science Conference, and a day after I proposed the same volcanism-driving mechanism in post #542, on the 'Dawn approaches Ceres' topic.

They make no mention of salt deposits though, as a consequence of the release of seawater, hence I expect we'll see evidence of that in spectral results from Dawn. Final confirmation of volcanism should occur by May or June, when central pits show up in those bright spots.