A model-based control framework for space debris management

The accelerating proliferation of space debris represents a serious and growing threat to the long-term sustainability of space operations. While modeling tools and mitigation guidelines have been developed over recent decades, the rapid expansion of commercial space activities has outpaced current regulatory mechanisms, which have struggled to keep pace with the rapidly evolving space mission environment. In response to this challenge, the GREEN SPECIES project, funded by the European Research Council, proposes an integrated, interdisciplinary framework for the robust control of the orbital environment. This work introduces a foundational element of the framework. A simplified one-dimensional statistical model of debris evolution is combined with a state-dependent linear feedback controller based on the differential Riccati approach. The model captures the dynamics of active satellites, inactive objects, and fragments across altitude shells, accounting for drag, launches, collisions, and disposal actions. The controller dynamically allocates mitigation actions such as post-mission disposal and active debris removal to steer the system towards a sustainability target defined by quantitative indices. This is achieved while minimizing a quadratic cost function and incorporating soft operational constraints, including the risk associated with removal operations and the cost of high-altitude activities. Results demonstrate the effectiveness of this approach in approximating desired environmental outcomes while optimizing resource use, offering practical insights for adaptive, cost-effective debris management. By linking control theory with debris evolution modeling, the GREEN SPECIES framework provides a novel policy-support tool for sustainable space governance.