Department of Earth Sciences

The geologically active icy moon Enceladus ejects subsurface material from its south pole into space in a plume of gas and ice grains. NASA’s Cassini spacecraft, which investigated the Saturn system between 2004 and 2017, captured and analysed plume material revealing deep-ocean hydrothermal systems, a porous, water-filled rocky core, and a large, diverse inventory of chemical species in its subsurface. Cassini detected these species in ice grains sampled directly from the plume as well as in Saturn’s E ring, which is a depository for Enceladean ice grains. Chemical species may be sampled by spacecraft in the plume and E ring, but many traverse a long journey through the subsurface prior to their detection. From their time under high-temperature and -pressure conditions within fluid inside the core, during their ascent through the ocean toward the surface, and finally their ejection into space, these compounds evolve chemically. To understand the chemistry observed by Cassini and future missions, these processes must be simulated in the laboratory.

The goal of ERC-AIMS project is to determine just how well these ejected chemical species reflect the composition of Enceladus’ ocean and the hydrothermal vents at the ocean-core boundary. To achieve this aim, the evolution of a variety of chemical species at shallow core depths and in the bulk ocean will be simulated using a series of interrelated experimental facilities. The chemical analysis of these species will be performed by various analytical techniques used in conventional chemistry - e.g. spectroscopy and mass spectrometry. Conclusions drawn from these laboratory simulations will be used not only for the better interpretation of mass spectrometric data from Cassini, but also the planning of future space missions toward Enceladus (e.g. ESA’s L4 mission), as well as the ongoing JUICE and Europa Clipper missions to the Galilean moons of Jupiter.