Mercuryʹs magnetosphere, exosphere and surface: low-frequency field and wave measurements as a diagnostic tool

Diagnostics that can be made with combined electric and magnetic field measurements at Mercury are reviewed. Fundamental electrodynamic questions which can be answered by means of a Mercury Orbiter are discussed. These include, solar wind-magnetosphere coupling, coupling to low altitude, exospheric or planetary surface conductivity, auroral particle acceleration, and magnetospheric substorms. It is concluded that a comprehensive instrumentation package for low-frequency fields and waves on a future Mercury Orbiter mission may yield significant new information of interest to magnetospheric as well as to planetary physics in general.