Plumes of water vapour and ice particles erupt from the south pole of Saturn’s moon Enceladus (Image: NASA/JPL/Space Science Institute)

THE ice plumes that bloom above Saturn’s icy moon Enceladus are almost certainly rooted in a subsurface sea of liquid water.

The Cassini spacecraft flew through a plume on 9 October 2008 and measured the molecular weight of chemicals in the ice. Frank Postberg of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, and colleagues, found traces of sodium in the form of salt and sodium bicarbonate. The chemicals would have originated in the rocky core of …