POSTECH and KIMM Joint Research Team
A team of domestic researchers has developed satellite propulsion technology that ignites immediately when needed in space without using highly toxic fuel and can be safely stored for a long time.
Professor Anna Lee from POSTECH’s Department of Mechanical Engineering, along with Senior Researcher Hongjae Kang from the Korea Institute of Machinery and Materials (KIMM), proposed a method to overcome the limitations of nitrous oxide-based propulsion systems by utilizing plasma technology. They experimentally demonstrated the potential of next-generation eco-friendly “storable propulsion systems,” as reported on the 5th. Their research was published in the international journal “Aerospace Science and Technology” in November.
As the operational efficiency of overseas launch vehicles, such as those from SpaceX, increases and the success of launches like Nuriho continues domestically, the path to space is perceived as closer than before. At this time, “storable propellants” become essential. Simply put, these are fuels that can be stored in a tank for extended periods with minimal risk of degradation or danger and can be used to power engines when necessary. However, widely used hydrazine-based fuels are highly toxic, necessitating complicated handling procedures and posing significant safety and environmental risks in case of leaks or contamination. Therefore, the industry has continuously sought safer alternatives to hydrazine.
Nitrous oxide has been considered a promising alternative because it is relatively easy to handle, being used as a sedative or auxiliary anesthetic in dentistry, thus reducing toxicity issues. However, using it with fuel often results in low efficiency, especially in small thrusters. Using a catalyst to facilitate the reaction can make the device bulkier and more complex. While pre-mixing fuel and oxidizer has the advantage of easy ignition, it also increases explosion risks, posing safety concerns.
The research team solved the dilemma of safety and efficiency with plasma. Plasma, a highly energized state of matter seen in phenomena like lightning or auroras, activates air (or gas) to initiate reactions even under challenging conditions for ignition. The technology applied in this study, “Rotating Gliding Arc (RGA) Plasma,” distinguishes itself by creating plasma in a 3D space within a short time, lowering the ignition threshold for combustion reactions.
The research team applied this technology to a dual-propellant system using nitrous oxide and methane, conducting experiments. Dual-propellant systems, which store fuel and oxidizer separately and supply them for combustion when needed, have advantages in storability and operational flexibility, but reliable ignition remains a key technical challenge.
The team confirmed immediate ignition was possible with just 30-100W of power and could maintain stable combustion even under ultra-lean conditions, which is typically an environment where combustion is difficult. Plasma effectively aided the reaction, allowing combustion to continue in these conditions.
Even under extreme conditions with an oxidizer-to-fuel mass ratio as high as 1000, the system operated stably without a catalyst, achieving an 87.8% combustion efficiency. The team likened plasma’s role to keeping a fire alive with damp firewood, effectively lowering the ignition threshold. Near-ideal fuel ratios showed efficiency close to the theoretical limit of 99.9%.
The reason this achievement garners attention is its safety and practicality. Reducing dependency on complex and heavy catalyst or preheating devices can lower the total weight of the propulsion system. Securing ignition without pre-mixing could reduce explosion risks and simplify operational procedures.
Professor Anna Lee explained, “Through plasma technology, we verified the potential of next-generation eco-friendly propulsion technology.” Senior Researcher Hongjae Kang noted, “It offers high reliability even at low power, expanding the range of applicable uses from small satellites to long-term mission propulsion.”
For reference:
“Aerospace Science and Technology (2025), DOI: [https://doi.org/10.1016/j.ast.2025.111256](https://doi.org/10.1016/j.ast.2025.111256)”