We expect more development from interest for volatile elements or molecules on Europa (Jupiter). It seems to me that H2O diagram shows that ice solid to gas (withouit liquid) by melting or to liquid (without gas) by subllimation, if there any heat (melting) sources or pressure (sublimation) respectively. This means that if no continuous heat source, there is no water (by melting), and that some rock presure at interior structure brings any sublimation-deposition (i.e. without water liquid phase). We are not sure suitable H2O model on Europa so far. The geological model on surface ice is considered to be not the case in our active Earth planet. Good luck more!
We expect more development from interest for volatile elements or molecules on Europa (Jupiter). It seems to me that H2O diagram shows that ice solid to gas (withouit liquid) by melting or to liquid (without gas) by subllimation, if there any heat (melting) sources or pressure (sublimation) respectively. This means that if no continuous heat source, there is no water (by melting), and that some rock presure at interior structure brings any sublimation-deposition (i.e. without water liquid phase). We are not sure suitable H2O model on Europa so far. The geological model on surface ice is considered to be not the case in our active Earth planet. Good luck more!