For the first time it has been shown that the Cassini-Huygens probe’s sampling of icy spray shooting from Saturn’s moon Enceladus contains large salt rich grains.
The spray was sampled by Cassini in 2005. The plumes were coming from the so-called “tiger stripe” surface fractures at the moon’s south pole. These tiger stripes are thought to have created the material for the faint E-ring that traces the orbit of Enceladus around Saturn.
Cassini made three passes through the plume in a 2008 and 2009. A piece of equipment on board called the cosmic dust analyser measured the composition of ejected grains. The particles were vaporised and then separated allowing analysis.
Only salt water underneath the surface could produce a steady outflow of salt rich grains. The salt rich grains have an “ocean-like” composition indicating most, if not all, of the expelled ice comes from the evaporation of liquid salt water rather than from the icy surface of the moon. When salt water freezes slowly the salt is “squeezed out” leaving pure water ice behind. If the plumes were coming from the surface ice, there should be very little salt in them, which is not the case, according to the research team.
Overall this points to a salt ocean 50 miles beneath the surface between the Rocky core and the icy mantle. This is kept in a liquid state by gravitationally driven tidal forces and heat produced by radioactive decay.
The Cassini spacecraft continues its mission to explore strange, new worlds to seek out new life and new civilisations, and boldly go where no man has gone before.