Study On Light Scattering Characteristics Of Dust Particles In Mars Environment

With the steady advancement of China's deep space exploration strategy,the Mars Exploration Project has become the most significant space exploration project following the manned spaceflight project and the Chang'e project.Due to the particularity of the Martian environment,the dust in the Martian atmosphere has become the main factor affecting the optical detection of Mars.Therefore,the study of the light scattering characteristics of the dust particles in the Martian atmosphere has important theoretical reference values to the environmental analysis of the Martian atmosphere,the optical image analysis of the Mars exploration,and the wireless laser communication projects implemented on Mars in the future.Firstly,the atmospheric and surface conditions on Mars are introduced.The vertical structure of dust particles on Mars and the cause of formation of dust suspension layer are analyzed.The particle size distribution of dust particles on Mars is fitted by lognormal distribution,and the complex refractive index corresponding to different wavelengths is given.The relationship between dust particle concentration and altitude and wind speed in Mars environment is studied.For spherical,elliptical,cylindrical and cuboid Martian dust particles,the scattering properties of particles at different laser incident angles are studied by T-matrix.The effects of the size of spheres,ellipsoids,cylinders and cuboids on the scattering properties of particles are analyzed.The extinction factors,scattering factors and absorption factors of ellipsoidal and cylindrical dust particles are studied and compared with the results of spherical particles calculated by Mie theory.For dust particle swarm with lognormal distribution,the variation of scattering characteristics with scattering angle is calculated and compared with the results of Pollack's study.The transmission attenuation and transmissivity of laser under different degrees of dust storms in the wave range of 0.21?m-40?m are calculated by Mie theory,and their relationship with the wavelength of incident light is analyzed.Mie theory and T-matrix are used to calculate the relationship between transmission attenuation and transmissivity as a function of concentration under dust conditions in Martian atmosphere.For the human eye's most sensitive green light at 0.55?m band,the relationship between visibility and dust concentration is analyzed.The comparison shows that the scattering properties of spherical particles calculated by Mie theory and T-matrix are equal.Finally,when there is no dust storm on Mars,the relationship between transmission attenuation and transmissivity as a function of height are studied.The results show that the scattering characteristics of single spherical and non-spherical particles vary widely,and the effects of different size ratios on the scattering characteristics of the same shape are also different.Under the dust storm conditions,Under the dust storm conditions,the high concentration of dust particles in the atmosphere of Mars leads to a large transmission attenuation.When there is no dust storm,the concentration of dust particles in the atmosphere of Mars is low,and the transmission attenuation is small.