材料粗糙度变化对卫星光谱红化效应的影响

在轨人造目标的地基观测光谱存在红化效应，影响对目标反射光谱的理解应用.目标在进入空间环境后外露材料表面粗糙度发生变化.本文结合材料的光谱散射特性、卫星轨道和观测条件，仿真分析了卫星表面材料粗糙度变化对红化效应的影响.基于文献中实验数据，设计不同粗糙度的卫星表面材料样本，模拟空间环境中材料表面粗糙度的变化.利用双向反射分布函数，建立不同粗糙度材料样本的光谱散射模型.理论模拟结果表明，材料表面粗糙度的变化会影响其光谱散射特性，散射光谱形态和散射分布取决于粗糙度及入射-反射几何关系.引入网格剖分和可见面片，利用材料双向反射分布函数，仿真计算卫星表面材料在不同粗糙度状态下，整个卫星在可见光波段的反射光谱信号.仿真结果表明，随着卫星表面材料粗糙度的增加，其反射光谱在600nm之后随波长增加而呈现上升趋势，这表明空间环境中外露材料表面粗糙度变化是卫星产生红化效应的原因之一. 

Influence of Exterior Materials Roughness Variation on Satellite Spectrum Reddening Effect

Remotely observed spectrometric characters of the objects in space with known exterior materials turned out to exhibits reddening effect,as compared to their corresponding laboratory spectra.The variation of the surface roughness of objects exterior materials in space environment is studied.Based on the spectral scattering characteristics of materials,orbit characteristics and observation conditions,the influence of surface roughness on reddening effect is simulated and analyzed.Some material samples are designed with different roughness by referring to the experimental data of related literatures,in order to simulate the variation in surface roughness of the materials exposed to the space environment.The spectrum scattering characteristics of the material with different surface roughness are theoretically modeled by Bidirectional Reflectance Distribution Function.The results show that the change of surface roughness affects the spectral scattering characteristics.The shape and distribution of scattering spectrum depend on the roughness and the geometric relationship between the incident and the reflection.The spectrometric characteristics in visible light band of the satellite with exterior material under different roughness conditions is simulated by summing all the contributing surface grid reflection scattering components.The results show that with the increase of the satellite surface roughness,the satellite reflection spectrum increases obviously as wavelength increases after 600 nm.It shows that in the space environment,the change of the surface roughness of the exposed material is one of the reasons for causing the satellite reddening effect.