Analysis on the solar irradiance fluctuations effect on the BepiColombo superior conjunction experiment

The BepiColombo mission (ESA/JAXA) is devoted to the exploration of Mercury, the innermost planet of the Solar system. Among the experiments on- board of the spacecraft, the Mercury Orbit Radio Science Experiment (MORE) aims to gather information about the surface and the internal structure of the planet, and to carry out fundamental physics tests, thanks to a state-of- the-art tracking system. During the cruise phase of BepiColombo, a general relativity test is performed in order to determine the Eddington parameter. Due to the proximity to the Sun, the solar irradiance random fluctuations have a dynamical effect that cannot be neglected. In this work a complete numerical simulation of the MORE fundamental physics experiment in cruise is carried out, taking into account the irradiance fluctuations. A precise orbit determination simulation has been used in order to assess the attainable accuracy on the determination of the Eddington parameter.