Chapter 5 - Removal of Large Space Debris by a Tether Tow

Abstract

In this chapter, we study a problem of removal of large space debris by a tether tow. A space transportation system is composed of two bodies connected by the tether. The first body is space debris (upper rocket stage or a large nonfunctional satellite) and the second body is a space tug. An attitude motion of the system in general and space debris is studied in the gravity field of the Earth under the action of the space tug thruster, aerodynamic drag, and the gravitational torque. Large space debris can strongly affect the motion of the space tug and the tether during the transportation process, which can lead to the loss of control of the transportation system. We suppose that the space tug has an attitude control system that maintains required orientation of the tug, so the tug is represented as a mass point. Particular attention is given to investigate the spatial motion of the space debris relative to the tether and to the space tug. Osculating elements of the orbit are used to describe the motion of the center of mass of the system. This chapter focuses on the dynamics of the space debris with flexible appendages and with fuel residuals that can affect the safety of the debris transportation process by a viscoelastic tether. Mathematical model of the attitude motion of the system is derived using the Lagrange formalism. To implement safe removal of space debris, recommendations for choosing parameters of the tug and the tether are given based on numerical and analytic calculations.