Stability in Orbit of the Automatic Earth Satellite in the Upper Atmosphere

Abstract

This paper is confined to a study of the stability of the spacecraft’s motion around its center of gravity. The body of the stabilized satellite will constantly tend to preserve a certain orientation in space, resisting any accidental causes, that is disturbing forces and moments, capable of deviating the craft from its given orientation. The introduction of the paper contains a survey of the methods proposed or employed in ensuring the stability of a satellite in orbit. These stabilizing methods are basedupon the utilization of one or several of the following factors: the gravity field potential gradient, magnetic potential gradient, aerodynamic pressure, radiation pressure, jet power, and gyroscopic effect. In addition to the aforementioned methods, another possible approach to the problem is. suggested. In certain circumstances, the scientific tasks assigned to the spacecraft may allow for the adoption of more inexpensive means apt to insure a certain orientation of its body in orbit. Thus, the last stage of the carrier may be provided with solid fuel, in which case the satellite’s stability in orbit may be obtained by means of a motion of rotation around its longitudinal axis, utilizing for this purpose the thrust of the last chemical fuel motor. The rapid rotation of the body of the satellite around its longitudinal axis, tangent to the orbit, can be achieved by equipping the engine of the last stage with a number of nozzles, placed on a circumference, with the axes of these nozzles inclined by an angle Tin relation to the longitudinal axis of the rocket. This paper therefore proposes a formula in the calculation of the minimum value of the angle T which in the above-mentioned conditions might insure the stability in orbit of an earth satellite. At first sight, it may be believed that an inclination of the nozzles greater than that resulting from proposed formula might improve the general stability of the satellite. In point of fact however, if the angle T is too great, a number of disadvantages arise, disadvantages which will be listed in the paper itself. There is of course also an upper limit of this angle, the study of which, however, is outside the scope of this paper.