Search for Exospheric Refilling and Emitted Natural Abundances (SERENA) is an instrument package on board the BepiColombo/Mercury Planetary Orbiter (MPO). It will investigate Mercury's complex particle environment that is composed of thermal and directional neutral atoms (exosphere) caused by surface release and charge-exchange processes, and of ionized particles caused by photo-ionization of neutrals as well by charge exchange and surface release processes. In order to investigate the structure and dynamics of the environment, an in-situ analysis of the key neutral and charged components is necessary, and for this purpose the SERENA instrument shall include four units: two neutral particle analyzers Emitted Low Energy Neutral Atoms (ELENA) sensor and Start from a Rotating FIeld mass spectrometer (STROFIO) and two ion spectrometers Miniature Ion Precipitation Analyzer (MIPA) and Planetary Ion Camera (PICAM).
SERENA can provide information on the whole surface-exosphere-magnetosphere coupled system and the processes involved, plus the interactions between energetic particles, the solar wind, micrometeorites and the interplanetary medium. This instrument deals with some of the main scientific objectives of the BepiColombo mission: composition, origin and dynamics of Mercury's exosphere and polar deposits; and structure and dynamics of Mercury's magnetosphere.
It is a package devoted to Hermean environment investigation. Mercury’s environment is a complex and tightly-coupled system where the magnetosphere, exosphere, and surface experience temporal and spatial variations linked to each other.