The ice covering Europa's entire surface may extend down many miles. Underneath this thick frigid layer may be a deep ocean. Astronomers are not sure of the depth of Europa's frozen crust and ocean, but they do know that there is a hard rocky core beneath the ice and water. It is likely that Europa has no mountains or cliffs because its surface is primarily made of ice, which cannot support as much weight as rocks or metallic substances and tends to flatten out over time. That is what scientists believe happened on Europa. Europa's ice is
toxic
opaque
slick
massive