Saturn’s icy moon Enceladus harbours a global ocean, which lies under an ice crust of just a few kilometres thickness. Through warm cracks in the crust a cryo-volcanic plume ejects ice grains and vapour into space providing access to materials originating from the ocean.

The presentation reviews the results from the two mass spectrometers aboard the Cassini spacecraft, which frequently carried out compositional in situ measurements of plume material emerging from the subsurface of Enceladus and discuss how these ice grains emitted from the oceanic surface can act as messengers of ocean properties. By probing these materials, humans for the first time are enabled to get insights into the inorganic and organic chemistry of an extraterrestrial liquid water environment.

We infer an ocean of mild salinity and alkaline pH. We find indication for hydrothermal activity to be occurring at the rocky ocean floor. The energy for these processes is probably delivered by tidal dissipation inside the moons core. Furthermore, recent ice grain analysis indicates the high abundances of phosphates and a rich organic chemistry in the ocean, with the occasional presence of concentrated macromolecular organic material. These insights rendered Enceladus as a prime candidate to search for extant life in our solar system.