SERENA (‘Search for Exospheric Refilling and Emitted Natural Abundances’) (Orsini et al. 2010) is an instrument package that will fly on board the BepiColombo/Mercury Planetary Orbiter (MPO); it 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 again by surface release processes. In order to accomplish the scientific goals, in-situ analysis of the environmental elements is necessary, and for such a purpose the SERENA instrument shall include four units: two Neutral Particle Analyzers (ELENA and STROFIO) and two Ion Spectrometers (MIPA and PICAM). In particular, ELENA investigates the neutral gas escaping from the surface of Mercury, and the related involved processes; STROFIO investigates the exospheric gas composition; PICAM investigates the exo-ionosphere extension and composition, and the close-to-planet magnetospheric dynamics; MIPA investigates the plasma precipitation toward the surface and ions energized and transported throughout the environment of Mercury.
The major scientific goals of SERENA are:
• Chemical and elemental composition of the exosphere
• Exo-ionosphere composition and distribution
• Surface emission rate and release processes
• Plasma precipitation rate
• Particle loss rate from Mercury’s environment
• Gas density profile asymmetries
Finally, 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 (Milillo et al., 2005)
Milillo, A., S. Orsini, P. Wurz, D. Delcourt, E. Kallio, R.M. Killen, H. Lammer, S. Massetti, A. Mura, S. Barabash, G. Cremonese, I.A. Daglis, E. De Angelis, A.M. Di Lellis, S. Livi, V. Mangano, K. Torkar, Surface-Exosphere-Magnetosphere System of Mercury, Space Science Reviews, 117, issue 3, 397-444, 2005.
Orsini, S. S. Livi, K. Torkar, S. Barabash, A. Milillo, P. Wurz, A. M. Di Lellis, E. Kallio and the SERENA team, SERENA: a suite of four instruments (ELENA, STROFIO, PICAM and MIPA) on board BepiColombo-MPO for particle detection in the Hermean Environment, Bepicolombo Special Issue on Planetary and Space Science, doi: 10.1016/j.pss.2008.09.012, 58, 166-181, 2010