The objective of SIXS is to perform measurements of X-rays and particles of solar origin at the position of BepiColombo.
The instrument is capable of broadband measurements of X-ray, proton, and electron spectra with high time resolution and a very
wide Field-Of-View.

  The surface of Mercury is bombarded with intensive solar X-rays and particle radiation, which make the Hermean surface glow in X-rays. 
  Changes of the input radiation are due to solar activity and eruptive phenomena on the Sun. 
  The radiation varies unpredictably with time scales from seconds to years and several orders of magnitude in intensity. 
  The X-ray glow of Mercury provides a "Hermean signature" in the form of fluorescence. The primary task of SIXS is to make observations 
  that are derivable to accurate physical estimates of solar X-ray, proton and electron irradiation at the surface of Mercury. 
  The surface is simultaneously observed by the Mercury Imaging X-ray Spectrometer (MIXS), a closely linked instrument. 
  Data provided by SIXS is mandatory for a valid fluorescence analysis of MIXS spectra. The solar X-ray monitor is also the single 
  source of this necessary data in orbital phases of Mercury while the planet is behind the Sun.

  Independent scientific objectives for SIXS are studies of temporal and spectral variability of solar X-ray corona, temporal behaviour 
  and X-ray spectral classification of solar flares, and temporal and spectral variability of proton and electron radiation near Mercury. 
  These will be obtained as bonuses, when the main task for the instrument is performed.