SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) NPA-IS (Neutral Particle Analyzer - Ion Spectrometer) - Scientific and Technological plan - Issue 1

Abstract

The SERENA experiment, proposed as a single IFE on board the BC/MPO, will investigate the Mercury’s complex particle environment that surrounds the planet. Such an environment is composed by thermal and directional neutral atoms (exosphere) originating via surface release and charge-exchange processes, and by ionized particles originated through photo-ionization and surface release processes. The crucial points for the knowledge of the environment and the evolution of Mercury, as listed in the Science Requirement Document (section 2.1.3, Mercury's Exosphere), are: 1) Composition and vertical structure (search for noble gases, isotopes, molecules and atoms of crustal origin); 2) Dynamics: day to night circulation, active to inactive regions; 3) Surface release processes, sources: e.g. regolith, meteorites, etc; 4) Search for ionosphere and its relation with neutral atmosphere; 5) Atmosphere/magnetosphere exchange and transport processes; 6) Escape, source/sink balance, geochemical cycles. In order to fulfil the listed tasks, in-situ analysis of the environmental elements is suggested in the Science Requirement Document (section 3.6, Analysis of Neutral and Ionized Particles). For such a purpose the SERENA experiment shall include four units: the Neutral Particle Analysers (NPA-ELENA and -STROFIO) and the Ion Spectrometers (IS-MIPA and -PICAM). In summary, SERENA is an experiment able to provide information on the whole surface-exosphere-magnetosphere system, as well as on the processes involved in this system, subjected to strong interaction with the solar wind and the interstellar medium.