Stage 2

Europa

The first ocean, under a young lid of ice

A global ocean under ice that is geologically young. The jump from dry Io to this much water is the first hard riddle of the sequence.

What the cameras and papers show

A global ocean sits under an ice shell tens of kilometres thick. Published volumes put that ocean on the order of Earth’s seas — often about twice as much.

The ice lid is young, not a four-billion-year museum. Double ridges and chaos terrain keep rewriting the surface. Hubble has reported possible water-vapor plumes; those detections remain debated.

Tides can keep an ocean liquid. They cannot invent the water if the previous face, Io, is dry sulfur-rock.

Europa Clipper is on the way to taste the chemistry of that ocean.

How this site reads it

This is the first-ocean chapter if the sequence is real. Io is fire. Europa is water.

The analog is easy: a hidden sea under ice. The identity is harder: that sea had to be acquired after a dry volcanic predecessor.

What would kill this stage

If Europa’s ocean is native ice from birth, with no volcanic predecessor, Stage 2 comes off the table.