Voyager program
Mass estimates from the Voyager program missions suggested that Enceladus was composed almost entirely of water ice. However, based on the effects of Enceladus's gravity on "Cassini", its mass was determined to be much higher than previously thought, yielding a density of 1.61 g/cm3. This density is higher than those of Saturn's other mid-sized icy satellites, indicating that Enceladus contains a greater percentage of silicates and iron.