Researchers at Tohoku University have revolutionized the removal of space debris and developed a plasma propulsion system that could potentially make Earth’s orbit safer.
Earth’s orbit is becoming more and more crowded. Thousands of abolished satellites, discarded rocket stages, and fragments from past collisions orbited the planet at a faster speed than bullets.
This expanding cloud of debris is at risk to active satellites and future crews.
Even debris just a few centimeters wide can cause catastrophic damage to a functional spacecraft given its extreme speed.
With the number of satellites expected to grow significantly over the next decade, scientists are competing to find safe and efficient methods before cleaning up this orbital disruption, before it becomes even bigger.
Understanding the dangers of space fragments
Understanding the threat of space debris is important to understand why such innovation is urgently needed.
Debris populations contain everything from old satellite parts to small pieces created by collisions and explosions. Even small pieces, like paint tips, can pierce the walls of a spacecraft at orbital speed.
The danger is not theoretical. Past incidents such as the collision between an active US satellite and an abolished Russian satellite in 2009 have created thousands of new fragments remaining in orbit today.
Each conflict increases the risk of a chain reaction, sometimes called Kessler syndrome. In Kessler syndrome, fragment collisions produce more fragments and part of the orbit cannot be used.
Plasma Promote: A New Approach
Plasma propulsion is at the forefront of efforts to combat space debris. This is a technology that uses overheated electric charging gas to generate thrust.
Traditionally, removal of space debris has relied on direct contact solutions of nets, harpoons, or robotic arms. Although innovative, these methods pose the risk of entanglement due to unpredictable tumbling of debris.
Plasma propulsion offers a contactless alternative. By firing a plasma stream with debris, the idea is that the Earth’s gravity will pull it back into the atmosphere, slowly slowing down until it burns out harmlessly there.
The challenge is to ensure that the removal satellite itself remains stable while performing this operation.
Japan’s breakthrough
Takahashi Sano, an associate professor at Tohoku University’s Graduate School of Engineering, has taken a major step towards solving this problem.
His research details the development of bidirectional plasma draining electroless plasma mass srusters.
Unlike traditional thrusters that fire plasma in one direction, Takahashi’s design involves the plasma ejecting the plasma stream back and forth.
This double ejection balances the force and slows down target debris while preventing removal satellites from being pushed out of course.
To further increase efficiency, Takahashi integrated a magnetic field structure called a cusp.
Laboratory vacuum testing showed that this configuration not only stabilizes the plasma propulsion system, but also triples the deceleration power compared to previous designs.
Why is Argon important?
Another important advantage of Takahashi’s plasma propulsion system is its fuel source.
Unlike traditional thrusters that often rely on expensive propellants like Xenon, this new system works with Argon and is a much cheaper and richer option.
This makes large debris cleanup missions more feasible and cost-effective, removing one of the biggest barriers to implementation.
From the lab to the track
So far, these tests have been carried out in a controlled laboratory environment. The next challenge is to demonstrate the performance of thrusters in real-world spatial conditions.
If successful, a satellite equipped with bidirectional plasma propulsion can lock into space junk and exclude it in about 100 days.
Takahashi’s plasma propulsion system represents more than just laboratory results. It provides a realistic pathway to maintain a safe and sustainable Earth orbit, one of the most pressing challenges of modern spaceflight.
As satellite constellations for communication, navigation and climate monitoring continue to expand, the ability to efficiently and safely remove dangerous debris is essential. Plasma propulsion could be an important technique that will change the tide of human battle against orbital junk.
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