Europa un bel posto per vivere 31st Annual Meeting of the DPS, October 1999 Session 66. The tidal-tectonic processes that appear to have governed Europa's geology require an ocean linked to the surface through a very thin crust, and provide a variety of evolving environmental niches, hospitable to life. Sequences and orientations of regional scale lineaments correlate with tidal stress patterns suggesting that there is a liquid ocean under the ice crust and rotation is non-synchronous. Subsequent diurnal tidal working of cracks creates ridges, by pumping liquid from below, and squeezing or spattering slush to the surface, with some distortion of the lip of the crack by the daily pounding. Strike-slip displacement and cycloidal cracking are driven by diurnal tides.
Cracks can form bands if dilated by regional extension, perhaps also driven by tides.
The same model of liquid water under a thin ice shell explains the characteristics of chaos areas as the result of melt-through from below. Subsequent cracks and ridges can mask older chaos areas. Melt-through explains how compression can accommodate dilation along bands without leaving a trace. Surface colorants correlate with locations where ocean water reached the surface. As a result of tides, liquid water regularly bathed crustal cracks and surfaces with heat and whatever nutrients are included in the oceanic chemistry, creating a variety of potentially habitable crustal environments, as well as addressing requirements for life in the ocean itself.