A new propulsion system developed by a researcher at Tohoku University, Japan, could provide a non-contact method for cleaning up Earth’s orbit.
This technology offers a solution to the continuous accumulation of space debris, such as defunct satellites and spent rocket stages.
Each piece of debris poses a risk of a potential collision that could damage active satellites, space stations, and disrupt navigation.
“Owing to their uncontrolled motion and velocity exceeding that of bullets, space debris orbiting around Earth poses a serious threat by a significant increase in the potential risk of collisions with satellites that support sustainable human activity in space,” said Kazunori Takahashi, an associate professor, in the press release dated September 9.
To remove space debris, the researchers have unveiled a new tech called a “bidirectional plasma ejection type electrodeless plasma thruster.”
The concept involves a satellite using its ion engine’s plasma exhaust to knock space debris into the atmosphere to burn up.
Plasma thruster design
Current cleanup methods often involve direct physical contact, mostly using robotic arms, nets, and tethers, which risk entanglement with the spinning debris.
Some recent deorbiting tech solutions incorporate plasma thrusters. The plasma force is expected to slow the junk, causing it to fall out of orbit and burn up in Earth’s atmosphere.
However, the plasma’s kickback force presents an issue by pushing the removal satellite away from its target junk. This counteracts the intended effect of slowing the debris down.
Professor Takahashi’s approach builds on this existing idea: using a removal satellite, or spacecraft, with a propulsion engine to fire a stream of plasma at space debris.
But so far, this concept hasn’t been successfully used because it pushes the target away.
To solve this, the new propulsion engine ejects two plasma streams simultaneously.
One aimed at the space junk to decelerate it, and another in the exact opposite direction to counteract the kickback force. This balanced thrust allows the removal satellite to remain stable and on-target.
“This propulsion engine applies deceleration force to the target object by ejecting plasma, while avoiding excessive thrust on itself by ejecting another plasma plume in the opposite direction,” Takahashi explained.
The research also revealed a boost in performance.
For this, they introduced a special “cusp” magnetic field to help contain and focus the plasma, enhancing the deceleration force.
System runs on argon
In tests conducted in a vacuum to simulate space, the team confirmed that their bidirectional plasma tech successfully balanced the engine’s thrust.
Moreover, it was discovered that the added cusp magnetic field improved performance, tripling the deceleration force reported in previous experiments.
An added benefit is that the system can run on argon, a propellant that is both cheaper and more abundant than traditional options.
“This achievement represents a significant technological advancement toward developing a propulsion system capable of efficiently and safely removing space debris,” Takahashi said.
As many as 14,000 pieces of junk are currently floating in low Earth orbit.
Professor Takahashi’s bidirectional thruster offers a sustainable solution for clearing this debris.
The thruster could target larger pieces of space junk, as these will most likely trigger a “Kessler syndrome” event.
This is a frightening scenario where a collision between a satellite and a piece of debris creates a chain reaction, leading to more collisions that could make large parts of low Earth orbit too hazardous for any spacecraft to pass through.
The findings were published on August 20, 2025, in Scientific Reports.
