Application of tether systems for lunar orbital missions

Abstract

The article examines the problem of deploying a flexible connection in a space tether system. The payload is located at the end of the tether. The main purpose of the system is to transfer the payload from a higher lunar orbit to a lower one. This problem is a key stage in the process of transferring a payload from orbit to the surface of the Moon. The main advantage of this formulation is the absence of fuel costs for the payload transfer process itself. At the same time, the orientation of the payload in space is provided by the presence of a flexible connection between the payload and the basic spacecraft in orbit. On the other hand, the complex coupled motion of the parts of the system under orbital conditions requires additional control and regulation to ensure the stability of the entire system. To analyze the coupled dynamics of the system, a mathematical model was developed. The system consists of two spacecraft, an orbital module and a payload, and a flexible tether between them. The tether is modeled as a flexible, elastic, extensible thread in a field of external forces using second-order partial differential equations. The motion of the terminal mass, the payload, is a dynamic boundary condition of the problem. This approach makes it possible to take wave processes in the tether into account and to estimate their contribution to the coupled dynamics of the system. As a result of the study, stability conditions for the deployment process in lunar orbit were obtained. These conditions formed the basis of the control mechanism placed on the orbital module. Numerical simulation showed the applicability of the proposed mechanisms for deployment control and system stabilization.