Towards an all-sky ion composition detector for the Saturnian system

Our current knowledge of the Saturnian moons is based in great part on measurements from the Cassini-Huygens mission; however, to this day, there are still outstanding questions regarding their habitability and prebiotic chemistry. In order to close these gaps, ESA’s next large-class mission (L4) has set its target on Enceladus. This mission will aim to characterise the chemically complex environment of Enceladus’ surface, plumes and exosphere, and their interaction with the external environment, such as Saturn’s magnetosphere and particles from the E-ring. In order to address these objectives, the inclusion of an ion mass spectrometer with increased mass resolving power would allow to determine the inventory of organic molecules in the atmosphere and, furthermore, determine if there’s organic synthesis proceeding within Enceladus.

The Cosmic Dust Analyser (CDA) and the Ion and Neutral Mass Spectrometer (INMS) from the Cassini-Huygens mission reported indirect evidence for the presence of complex organic molecules and bioessential compounds in Enceladus’ plume. These instruments relied on ionisation techniques that fragment molecules, which complicated the molecule identification from the mass spectra reconstruction. Carbon-foils usually used in ion mass spectrometers also induce fragmentation of molecules. To avoid physical impact and potentially provide direct measurement of complex molecules, we propose to pursue modulated Time-of-Flight (TOF) ion mass spectrometer technique, such as the Hadamard gating used by the Planetary Ion CAMera (PICAM) onboard the BepiColombo mission. In this poster, we report the progress on our Combined Hybrid Ion Mass Energy Resolver for Astrobiology (CHIMERA) instrument concept, an all-sky ion composition detector based on the heritage from PICAM. We present the design and performance requirements necessary for this instrument along with the preliminary ion optics configuration.