We present the results of a numerical simulation of energetic proton propagation in a model of Hermean magnetic field. The analysis is in connection with the scientific work of the particle detector of the Solar Intensity X-ray and particle Spectrometer (SIXS) on-board BepiColombo, which is to be launched in 2014. In this work we have used a test particle simulation model developed by Vainio and Sandroos of the University of Helsinki.
Mercury's environment is a complex system, resulting from the interaction between the solar wind, magnetosphere, exosphere and surface. The mission BepiColombo, a joint project of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) will be equipped with scientific instruments for detailed observation of Mercury's magnetic field and the magnetosphere. SIXS will investigate the direct solar X-rays and energetic proton and electron fluxes in the planet's environment.
The flux distribution of energetic protons on the surface of Mercury and in the magnetopause is studied at different locations of the simulated BepiColombo/MPO like orbit around the planet. Two primary simulations were carried out: first, an orbit with periherm 2840km and apoherm 3940km and second, a surface skimming circular orbit. Motivation for circular orbit was to understand the distribution at the magnetopause of particles hitting the surface of the planet as viewed from above the surface on the noon-midnight meridian. The response of several energy levels of particles to different locations in the static magnetic field is studied by analysing latitude-longitude maps of flux distribution and asymptotic directions through various widths of instrument view cone. SIXS experiment uses five such view cones. The view cone, which is approximately in the anti-nadir direction, was targeted in the simulation. Data were compiled at locations with a 30 degree separation (with respect to latitudinal plane) along the orbits. Interpretation of the data was realised though a few MATLAB® subroutines and functions.
The results suggest that SIXS is capable of providing data from targeted areas to perform relevant and specific tasks for MIXS (Mercury Imaging X-ray Spectrometer) as expected and planned. It was found out that in order to accurately describe certain propagation behaviours we need to improve the simulation to have the ability to map the path of a specific particle.
Concise summaries of the planet Mercury, BepiColombo mission and Solar Energetic Particles have been provided along with supporting appendices. Also the basic principles behind important numerical techniques used have been introduced.
