Criterion choice and taking into account the contamination films composition at the estimation of the joint contaminating influence of the own external atmosphere and stationary plasma thrasters

It is viewed the criteria, used at the estimation of the joint contaminating influence of the own external atmosphere and plasma, generating by stationary plasma thrusters. It is proved the transition from «deposited mass» criteria to the «optical degradation». It is proposed the interpolator^ model, which allows to estimate the change of the optical characteristics of the functional surfaces of the spacecraft. The influence of the metal particles, which are the part of the dispersion product on the optical characteristics of the covering, is viewed.