GX was a design for an expendable launch system intended to compete in the commercial satellite launch sector. The system had developed by Galaxy Express Corporation, a joint venture between IHI Corporation (IHI), the Japan Aerospace Exploration Agency (JAXA), United Launch Alliance (ULA), Lockheed Martin Corporation (LM) and several other Japanese companies.

IHI Corporation , formerly known as Ishikawajima-Harima Heavy Industries Co., Ltd. is a Japanese engineering corporation headquartered in Tokyo, Japan that produces and offers ships, space launch vehicles, aircraft engines, marine diesel engines, gas turbines, gas engines, railway systems, turbochargers for automobiles, plant engineering, industrial machinery, power station boilers and other facilities, suspension bridges and other structures.