SERENA on BepiColombo
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Scientific objectives

Search for Exospheric Refilling and Emitted Natural Abundances (SERENA) is an instrument package that will fly onboard Mercury Planetary Orbiter (MPO), and that will be able to provide information about the whole surface–exosphere–magnetosphere system, as well as about the processes involved in this system, subjected to strong interaction with the SW and the interplanetary medium. In the Hermean environment the interaction between energetic particles, solar radiation and micrometeorites with the Hermean surface gives rise to both thermal and energetic neutral populations in the near-planet space. Such populations will be recorded by the SERENA neutral particle analyzers, namely Emitted Low Energy Neutral Atoms (ELENA) sensor and Start from a Rotating FIeld mass spectrometer (STROFIO) (form a Greek word meaning ‘rotate’ it is a neutral gas mass spectrometer based on a rotating electric field). The photoionized or charged component of the surface release processes as well as the precipitating and circulating ions in the Hermean magnetosphere will be recorded by the SERENA Ion Spectrometers, namely Planetary Ion Camera (PICAM) and Miniature Ion Precipitation Analyzer (MIPA). In particular, ELENA will observe the sputtered high energy atoms (SHEA) escaping from the surface of Mercury, investigating the related involved processes; STROFIO will provide the thermal exospheric gas composition; PICAM will permit to derive the exo-ionosphere extension and composition, and the close-to-planet magnetospheric dynamics; MIPA will detect the plasma precipitation toward the surface and ions energized and transported throughout the environment of Mercury.

In this perspective, the major SERENA scientific objectives may be resumed as in the following:

Primary Objectives:

    Chemical and elemental composition of the exosphere
    Neutral gas density profiles and asymmetries
    Exo-ionosphere composition
    Exo-ionosphere spatial and energy distribution
    Ion precipitation rate
    Surface emission rate and release processes (both neutrals and ions)
    Particle loss rate from Mercury's environment

Further Objectives:

    Remote sensing of the surface composition
    Magnetosphere structure and dynamics
    Planetary response to solar wind variations
    ENA imaging applications for comparative solar-planetary relationship
    Heavy ion sputtering products