Tohoku University's Plasma Thruster Offers Novel Solution for Space Debris Removal

The growing issue of space debris in low Earth orbit (LEO) presents a significant hazard to operational satellites and the International Space Station. This orbital clutter, consisting of defunct satellites, rocket stages, and fragments from collisions, travels at speeds exceeding 7 kilometers per second, posing a risk of catastrophic damage to active spacecraft. The theoretical Kessler Syndrome describes a potential cascade of collisions that could render LEO unusable.

In response to this challenge, researchers at Tohoku University in Japan have developed an innovative plasma propulsion system for contactless space debris removal. Led by Associate Professor Kazunori Takahashi, the system utilizes a "bidirectional plasma ejection-type electrodeless plasma thruster." This technology ejects plasma in two opposing directions: one stream targets the debris to decelerate it, while the other stream counteracts the reaction force, stabilizing the removal satellite. This balanced thrust allows the satellite to maintain its position while effectively slowing the debris.

Laboratory experiments have demonstrated the thruster's capability to generate a decelerating force of approximately 25 milli-Newtons (mN) with an input power of 5 kilowatts (kW). This performance is approaching the estimated 30 mN required to deorbit a 1-ton, 1-meter-class piece of debris within a 100-day timeframe. The system's efficiency is further enhanced by a unique magnetic field configuration known as a "cusp," which helps contain and direct the plasma, tripling the deceleration force compared to earlier models.

Unlike direct-contact methods such as nets or robotic arms, which carry risks of entanglement with tumbling debris, the bidirectional plasma thruster offers a contactless approach, enhancing safety and reducing mission complexity. Furthermore, the system's compatibility with argon as a propellant makes it a more cost-effective solution, as argon is cheaper and more abundant than traditional propellants like xenon.

While the technology has shown significant promise in laboratory settings, further research and development are planned, including testing in large space-simulation chambers and eventual orbital demonstrations. The successful implementation of this technology could provide a scalable, safe, and economically viable method for mitigating the growing threat of space debris, ensuring the long-term sustainability of human activities in orbit.