Existing space debris spans a wide range from old satellites and rocket parts to simple nuts and bolts. This poses a significant long-term threat to space safety. Kazunori Takahashi from Tohoku University worked on an innovative solution for effectively eliminating space debris. The core of the technique involves using a plasma exhaust from an ion engine to exert a pushing force on the debris. In this way, the debris surpasses its orbit of displacement, enters the atmosphere, and is safely decommissioned.
Initial designs faced some limitations because ion engines are generally designed to push spacecraft directly. To overcome this, Takahashi developed a motor that emits exhaust from two different directions of the spacecraft. This way, the thrusts from the two exhausts balance each other, keeping the deorbiting satellite in a stable position. This innovation is called a bidirectional plasma ejection electrostatic plasma thruster.
For a reinforced system, instead of conventional xenon gas, low-cost argon is used, which has similar efficiency. Argon is ionized to produce plasma, aiding in more effective pushing of space debris through the thruster nozzle. Additionally, a special “magnetic tip” has been developed; this tip allows for more efficient separation of plasma from the discharge wall, enabling more plasma to exit from the nozzle. As a result, laboratory tests show a tripling of power output and thrust up to 25 mN. This force allows for much more efficient energy use in removing space debris from orbit.
Although the thrust force of an ion engine is initially limited compared to chemical rockets, it increases over time to become effective. For example, to deorbit a 1-ton, 1-meter diameter piece of debris in less than 100 days, a continuous thrust of about 30 mN is required. This level of power indicates a higher thrust than that used in the ion engine for the Hayabusa2 mission. However, Takahashi’s developed system’s high power consumption becomes a significant advantage in fighting large-scale debris. This approach could provide an effective solution against widespread space debris.
