The Liquefied Natural Gas (LNG) propulsion system we are currently developing is a new propulsion system that can attain propulsive power by burning LNG (primary component is liquefied methane) and liquid oxygen in a rocket engine.

Up until now, JAXA has developed liquefied hydrogen and liquefied oxygen propulsion systems used in the first and second stages of the H-IIA Launch Vehicle, and a solid fuel rocket for each stage of the M-V Launch Vehicle. In terms of performance, the liquefied hydrogen propulsion system should be the most appropriate. So why is JAXA developing a LNG propulsion system now?

LNG has a high density, enabling for the miniaturization of the whole propulsion system. Thus LNG is more suitable for a first stage engine compared to liquefied hydrogen. Since LNG is also suitable for long-term storage in the void of space, it is anticipated that a LNG propulsion system could be utilized in an on-orbit transporter that travels in space. Additionally, as a hydrocarbon fuel, LNG doesn't generate much soot, and there is also a possibility for LNG to be utilized in a reusable propulsion system for a space sight-seeing rocket, etc. In this manner, LNG propulsion can be used in various space transportation systems for future space activities. Our mission is to develop a small-scale LNG engine as a first step toward developing a LNG propulsion system in order to utilize it for future space activities.

Basic research on similar kinds of rocket engines has been performed in the U.S., Europe, Russia, and South Korea. We are trying to be a front runner in the world competition to develop a LNG propulsion system. Despite many difficulties in developing the new engine and propulsion system, we are making our best efforts to overcome such difficulties and make a LNG propulsion system that we can be proud of throughout the world.