Water on Enceladus

Cassini's Enceladus flyby on Bastille Day, 2005.

In the February 7 issue of NATURE, researchers conclude that Enceladus' South Pole contains a vast lake with temperature of about 0 degrees Celsius. This temperature forms a triple point where water vapour, liquid and ice mix. On Enceladus, gaseous water reaches the surface at greater than escape velocity. They form the enormous pumes observed erupting from the south Pole.

The molecules of hydrogen and oxygen escape the moon to resupply Saturn's E Ring. Without resupply, Saturn's Rings would decay to nothing within 100 million years. We would then face the self-centred question of why the Rings would exist in just the right time for humans to enjoy them. From observing Enceladus, we can conclude that the Rings are long-lived features.

The source of heat keeping this lake warm is considered unknown. Why the heat is concentrated at the South Pole is yet another mystery. Enceladus' interior a great place to find a Black Hole. Ionised gas swirling around the singularity generates a magnetic field with the "positive" pole in the South. Like the classic picture of a Black Hole, twin jets are formed from particles spiralling around magnetic field lines. The Northern jet is composed of electrons which are absorbed by the moon's interior. The Southern jet is composed of heavier ions which penetrate to the surface. This warm jet keeps the South Polar region hot.

Enceladus research applies directly to Earth, as our Antarctic research has found huge subsurface lakes. Paradoxically, Earth's South Pole could also hide a "hot spot!" During this cold Winter, the climate is always on our minds. Cassini will have its closest encounter with Enceladus this March 13.