Gas Plume Impingement Technique for Space Debris De-Tumbling

Active Debris Removal (ADR) is one of the current hot spots in space research. Plenty of engineering challenges, it deals with uncooperative and tumbling orbiting objects to be approached and captured autonomously by another space vehicle, to eventually change their dynamics either directly transferring them to a disposal orbit or providing a control device to be attached to the dead element to make it controlled up to disposal. Different techniques are being proposed in literature, starting from the classical robotic arm to grasp the target up to action-reaction principle exploitation with no contact at all, such as gas plume impinging on the object surfaces to change its momentum. In particular, the use of proximity blow effects of a chemical thruster can be exploited to intervene on the uncooperative object angular momentum to control its rotational dynamics and prepare it for capture. Chemical propulsion is a high TRL technology that would not require long development and validation plan for the proposed application. A key point for this technology to be effective stays in evaluating the actual energy transfer between the gas particles and the uncooperative object, and its sensitivity to the several parameters the scenario depends on. This paper discusses the numerical simulator implemented at Politecnico di Milano to assess the feasibility and performance of this attitude control strategy, and its sensitivity to the numerous parameters involved in its design, looking for criticalities, benefits and drivers. The physical mechanism of momentum transfer, at the base of the simulator, is described at first: the investigation of the momentum transfer mechanism requires the definition of a plume model and a plume impingement model to simulate the interaction with the debris surface. The effects of the impinging plume on the angular dynamics of the debris object are then presented. An application of the method to a study case is presented to show the effectiveness and the applicability of this method. The effects of the system physical characteristic on the dynamics are also discussed. It is demonstrated, through the above-mentioned simulator, how the concept of de-tumbling targets using gas plume impingement may be very attractive in future ADR missions: attitude control strategies can be found to fulfil the requirements of de-tumbling space debris with chemical engine to safer face the subsequent disposal phase.