Rev 61 Enceladus (March 12 2008) Options

[Holder of the Tw...]

The mission description PDF is now online.

Enceladus 3 Flyby

[elakdawalla]

Gordan is right. Those distinctive Enceladan craters with up-domed floors, where the domes are heavily fractured, are very easy to explain through the process of "viscous relaxation," where the crater looked normal (bowl shaped or whatever) when it formed, but over time, and with help from heat conducting from the interior, gravity causes the ice in the crater to flow (in the solid state -- no volcanism or anything required here) to equalize the gravitational potential. Short-wavelength features take longer to relax because the strength of the ice comes in to play, so you get the most deformation acting on the longest wavelength, which is the up-down-up of the crater rim-floor-rim. As the floor domes upward, there are extensional stresses along the top of the dome, so it fractures. This is basically the same kind of stress regime that is being proposed to explain the "spider" feature in the center of Caloris as seen by MESSENGER on Mercury.

I looked around for some papers on viscous relaxation on Enceladus and this is what I came up with that's in the public domain.
http://www.lpi.usra.edu/meetings/icysat2007/pdf/6051.pdf
http://www.lpi.usra.edu/meetings/lpsc2007/pdf/2237.pdf

Mgrodzki, as ugordan pointed out here, those are stars. It's a long exposure becuase of the eclipse.

--Emily