Determining of the spacecraft aerodynamic characteristics at a rarefied gas flow

Abstract

A plane motion with respect to the center of mass of an uncontrolled satellite with a decrease from low circular orbits under the influence of gravitational and restoring aerodynamic moments is considered. The influence of design-ballistic parameters (initial conditions of angular motion, static stability margin, and inertia moment ratio) on the satellite angular motion (rotation, oscillations) is investigated. A satellite in low circular orbits under the action of a gravitational moment and a restoring aerodynamic moment, having a sinusoidal dependence on the angle of attack, was investigated by the method of the phase plane, while the change in the density of the atmosphere during the motion is neglected. Transitional modes of satellite motion relative to the center of mass at the initial part of the descent trajectory in the atmosphere under the action of a restoring aerodynamic moment, which has the form of a biharmonic series in angle of attack, are considered, while the effect of the gravitational moment is neglected. The cases of satellite motion relative to the center of mass at the initial part of the descent trajectory to the atmosphere under the action of a restoring aerodynamic moment, which is described by Fourier series in angle of attack with the three first harmonics, are investigated. The phase plane method has been used to investigate cases of the satellite plane motion relative to the center of mass as it descends from low circular orbits under the influence of a gravitational moment and a restoring aerodynamic moment, which has the form of a biharmonic series in angle of attack. Formulas have been obtained that allow one to determine the flight altitudes at which the character of the satellite angular motion is changing, as well as formulas for the probability of falling into oscillations with respect to one or another equilibrium position in the angle of attack. The analysis of the effect of design-ballistic parameters on the flat angular motion of a Cube Sat while descending from low circular orbits is carried out.