Enceladus Plume Through the Eyes of the Cassini Ion Neutral Mass Spectrometer

The Cassini Ion Neutral Mass Spectrometer has measured the composition of the plume of Enceladus on multiple flybys. This talk details our evolution of understanding of the plume composition. The gas composition is largely water vapor with a few percent admixture of carbon dioxide, ammonia, methane, molecular nitrogen or carbon monoxide, and a host of trace organic compounds. The limitations of our present understanding will be discussed as a context for how we bridge our present knowledge gap using new types of instrumentation. Specific measurements that can remove the present ambiguities and extend the search for habitability and life beneath the surface of the ice will be presented.