The increasing amount of space debris orbiting Earth poses a significant threat to operational satellites and the International Space Station. Over 14,000 pieces of junk, ranging from tiny fragments to defunct satellites, clog low Earth orbit, creating a hazardous environment. Current methods for removing this debris, such as robotic arms and nets, face challenges due to the unpredictable tumbling motion of much of the junk. However, a groundbreaking solution is emerging from Tohoku University in Japan.
Kazunori Takahashi has developed a bidirectional plasma ejection-type electrode-less plasma thruster – a novel ion engine design capable of efficiently removing space debris without direct contact. Unlike traditional ion engines that propel spacecraft forward, Takahashi's design employs two exhausts pointing in opposite directions. This ingenious configuration allows the removal satellite to maintain its position while using the plasma exhaust to gently nudge debris out of orbit. The system utilizes argon gas, offering a cost-effective alternative to the commonly used xenon.
The thrust produced by a single ion engine is initially low, but it builds over time. To effectively de-orbit a significant piece of debris (e.g., a 1-ton object) within 100 days requires a consistent 30 milli-Newtons (mN) of thrust – a challenge for conventional designs. Takahashi's system, however, surpasses these limitations. By incorporating a magnetic cusp, which reduces plasma loss and directs more towards the thruster nozzle, he achieved 25 mN in laboratory tests – tripling previous output.
This increased power output is crucial for addressing the threat of Kessler syndrome, a chain reaction of collisions that could render large sections of low Earth orbit unusable. The ability to remove larger pieces of space junk mitigates this catastrophic scenario. The technology requires several kilowatts of power, significantly more than previous systems, but its potential benefits in securing access to space far outweigh the energy demands.
Takahashi's research, published in *Scientific Reports*, represents a significant leap forward in space debris mitigation. The bi-directional plasma thruster offers a safe, efficient, and scalable solution to a pressing global challenge, ensuring the long-term sustainability of space exploration and satellite operations.
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Originally published at: https://www.space.com/technology/new-space-junk-removal-idea-using-ion-engine-exhaust-to-knock-debris-out-of-the-sky
