Active debris removal: A review and case study on LEOPARD Phase 0-A mission

The growing number of space debris is alarming as it threatens space-borne services. Hence, there is an increasing demand to remove space debris to ensure sustainability and protect valuable orbital assets. Over the past few years, the research community, agencies and industries have studied many passive and active debris removal methods. However, the current technology readiness for space debris removal is still low. This paper first presents a comparative study of various space debris removal technologies to address the knowledge gap and quantify the challenges. This paper reviews the current state-of-the-art space technologies relevant to Active Debris Removal (ADR) missions. Detailed trade-off analysis is then presented based on the Low Earth Orbit Pursuit for Active Removal of Debris (LEOPARD) Phase 0-A study; this study is part of the United Kingdom (UK) Space Agency's Active Debris Removal programme. The ADR mission scenario considered in this paper comprises a chaser spacecraft equipped with recommended technologies to capture non-cooperative targets safely. The final capture technology for the LEOPARD mission consists of an active robotic manipulator and a passive net capture mechanism. An analysis of the coupled-body dynamics of the chaser spacecraft carrying the robot manipulator and the targeted debris is carried out in simulation using Simscape^TM. The chaser spacecraft comprises Airbus's Versatile In-Space and Planetary Arm (VISPA) mounted on a base spacecraft from Surrey Satellite Technology Ltd. (SSTL); the targeted debris is SSTL's Tactical Operational Satellite (TOPSAT). The simulation results show dynamic changes in the chaser robot and the target satellite while performing non-cooperative capture. The simulation study accounted for various operational scenarios where the target is stationary or in motion. Further, for different modes of operation, the worst-case end-effector capture force limits were determined using open-loop control to execute a safe capture. Overall, the results presented in the paper advance the current state-of-the-art of robotic ADR and offer a significant leap in designing close-range motion and force control for stabilising the coupled multi-body system during capture and post-capture phases. In summary, this paper pinpoints the technological gaps, identifies barriers to realising ADR missions and offers solutions to catalyse technology maturity for protecting the space ecosystem.