Defunct Satellites in Nearly Polar Orbits: Long-term Evolution of Attitude Motion

TL;DR

This paper models and simulates the long-term attitude dynamics of defunct satellites in nearly polar LEO, considering gravity gradient, eddy currents, orbit evolution, and residual magnetic moments to aid debris mitigation efforts.

Contribution

It introduces a more accurate eddy current torque model and analyzes the combined effects of multiple factors on satellite attitude evolution.

Findings

Identified the significance of orbit evolution and residual magnetic moments in attitude dynamics.

Demonstrated the existence of various final attitude regimes.

Provided insights into the intermediate exponential deceleration phase.

Abstract

Low Earth orbits (LEO) are known as a region of high space activity and, consequently, space debris highest density. Launcher upper stages and defunct satellites are the largest space debris objects, whose collisions can result in still greater pollution, rendering further space missions in LEO impossible. Thus, space debris mitigation is necessary, and LEO region is a primary target of active debris removal (ADR) projects. However, ADR planning requires at least an approximate idea of the candidate objects' attitude dynamics, which is one of the incentives for our study. This paper is mainly focused on modeling and simulating defunct satellites. The model takes into account the gravity gradient torque and the torque due to eddy currents induced by the interaction of conductive materials with the geomagnetic field. A better understanding of the intermediate phase of the exponential deceleration is achieved owing to a more accurate model of the eddy currents torque than in most prior research. We also show the existence of other important factors in the studied dynamics such as evolution of the orbit itself and the residual magnetic moment, which both contribute to the overall attitude motion evolution and the variety of the final regimes.