The Mercury Imaging X-ray Spectrometer: instrument overview

We report progress in the design of the BepiColombo Mercury Imaging X-ray Spectrometer (MIXS). This instrument consists of two modules; a Wolter I soft X-ray telescope based on radially packed microchannel plate optics (MIXS-T) and a profiled collimator which uses a square pore square packed microchannel plate array to restrict its field of view (MIXS-C). Both instrument modules have identical focal planes (DEPFET macropixel array) providing an energy resolution of better than 200 eV FWHM throughout the mission. The primary science goal of MIXS is to perform X-ray fluorescence spectroscopy of the Hermean surface with unprecedented spatial and energy resolution. This allows discrimination between different regolith types, and by combining with data from other instruments, between competing models of crustal evolution and planetary formation. MIXS will also probe the complex coupling between the planet's surface, exosphere and magnetosphere by observing Particle Induced X-ray Emission (PIXE).