| In recent years,Mars exploration has become one of the most popular research topics in deep space exploration,and the sandstorm environment of Mars has become the main factor affecting the optical exploration of Mars.This paper mainly studies the effects of dust storms on the transmission characteristics of polarized light in the complex atmosphere of Mars,providing theoretical support for improving the performance of optical exploration and wireless laser communication system on Mars in the future.This paper divided into four parts:the first part mainly analyzes the physical properties of Martian dust environment,including the complex refractive index,atmospheric density,particle size distribution,etc.,and compares them with the earth's environment,explain the reason of the Martian environment prone to dust storms,and the uniqueness of dust storms on Mars,it is the study of the basis of the laser transmission characteristics in the Martian dust environment.In the second part,the spectral scattering characteristics of single non-spherical Martian dust particles are studied,including single scattering albedo,scattering phase function and other optical characteristics.The third and fourth parts focus on multiple scattering and study the propagation characteristics of unpolarized and polarized light based on Martian dust particles following lognormal distribution.The main conclusions of specific calculation are as follows:(1)The extinction efficiency factor and scattering efficiency factor of non-spherical and spherical Martian dust particles are greatly different.The maximum difference between them is 2.77635 and 2.76728,while the scattering characteristics of Chebyshev particles(n=2)are the closest to those of spherical particles.In addition,the variation trend of the transmission and attenuation efficiency(with wavelength,particle number concentration and height)of non-spherical Martian dust particles is basically the same as that of spherical dust particles,and the closer the size ratio is to 1,the more similar it is to spherical dust particles.(2)Using the Monte Carlo stratification method,perform stratified calculations on the complex atmosphere of Mars and compare the results with the non-stratified calculations.The results calculated by layering and without layering are very different.On the whole,the transmittance calculated without layering is larger than the transmittance calculated by layering.This is because when there is no layering,the particles are not considered.The number density varies with height,and the boundary conditions of each layer are ignored,so the calculated transmittance is greater without layering,but this result is also inaccurate compared to layering.In addition,it can be seen that under the selected wavelengths,the transmittance corresponding to 7.46?m is the largest,indicating that this wavelength is most suitable for laser communication in the Martian environment.(3)Using Monte Carlo simulation method to study the transmission characteristics of polarized light in the complicated atmospheric environment of Mars.The greater the particle number concentration or the longer the transmission distance,the more obvious the deflection.Taking a wavelength of 0.55?m as an example,the calculation results:the smaller the effective particle size,the more serious the depolarization,and the difference between the depolarization degrees corresponding to wind speeds of 15.3m/s and 1.7m/s is nearly two orders of magnitude.In addition,since the scattering coefficient and absorption coefficient of the laser light at the wavelength of 7.46?m are small,its polarization retention is better when it is transmitted in Martian dust.The absorption coefficient of the 0.66?m laser is the smallest,so the vertical and horizontal intensity attenuation is the slowest when propagating in Martian dust.Finally,the Martian atmosphere is layered in the vertical direction and the polarization characteristics of horizontally polarized light when transmitted in the vertical direction are calculated. |
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