Space station Mir aerodynamics along the descent trajectory

A controlled descent of space station Mir requires the choice of an optimal configuration (positions of solar arrays) that allows one to minimize the disturbing aerodynamic torques and maximize the drag. An approximate approa ch for choosing the positions based on free-molecular analysis is developed . The aerodynamic characteristics of the chosen configurations are studied by engineering and statistical methods along the descent trajectory. The st udy showed that a decrease in the flight altitude from 200 to 130 km does n ot exert a noticeable effect on the magnitude of the force and moment coeff icients and also revealed the reasons for the decreasing accuracy of the en gineering prediction. It was shown that the gas/surface interaction model s ignificantly affects the torques and, therefore, the choice of the optimal configuration.