Which crucial element confirms that Enceladus’s liquid water is interacting with rock, distinguishing it from merely having static water ice?

The confirmed presence of various salts and evidence of hydrothermal activity

The existence of liquid water is only the first prerequisite for habitability; its interaction with geology is paramount for energy and nutrient cycling. The analysis of the plume materials ejected by Enceladus provided strong chemical evidence that the water is actively interfacing with the moon's interior. Specifically, the confirmed presence of various salts dissolved in the water indicates chemical exchange with underlying minerals. Furthermore, the detection of molecular hydrogen points toward active hydrothermal vents on the seafloor. This combination—salty water interacting with rock and venting chemicals—is what makes the environment chemically rich and dynamic, surpassing the habitability potential of a simple, isolated body of frozen water ice.