Japan moves forward with replacement for H-2A rocket

Armed with an initial tranche of government funding for a next-generation rocket, the Japan Aerospace Exploration Agency plans to partner with a private company to lead development of a launcher to replace Japan's H-2A rocket by the early 2020s.

Concepts for the H-3 rocket in various configurations with and without solid rocket boosters. Photo credit: JAXA Mitsubishi Heavy Industries Ltd., the prime contractor for Japan's current H-2A and H-2B rockets, is almost certain to lead the industrial consortium to develop, manufacture and operate Japan's new H-3 rocket.

JAXA invited bids from Japanese industry Feb. 27 for an industrial partner on the H-3 rocket program. Selections are expected by the end of March.

"The Committee on the National Space Policy of the Cabinet Office recommended that the private sector be involved to play an important role throughout the new flagship launch vehicle project to make it an internationally competitive launch vehicle," JAXA said in its Feb. 27 announcement. "By including a private company, the committee said that the ability and power of the private sector should be fully leveraged in the development and ... that company shall also be able to provide launch services autonomously."

The preliminary schedule calls for the new flagship H-3 rocket to make its first launch in 2020.

"The new flagship launch vehicle will be freshly developed with a goal of securing Japan's autonomous launch capability of satellites and other payloads while acquiring international competitiveness in the space transportation field and maintaining and developing technical and industrial bases," JAXA said in a statement posted on its website.

Japanese officials say the two-stage H-3 rocket should be less expensive and flexible in launching often with different types of satellites for government and commercial customers.

A new hydrogen-fueled LE-X engine is in development for the H-3 rocket's first stage. Two of the engines, each generating about 300,000 pounds of thrust, will power the H-3 rocket's first stage.

The LE-X engine features an open expander cycle, in which hydrogen from the engine turbopump is diverted to the main combustion chamber's cooling channels and then used to drive the turbines before being injected into the combustion flow at the nozzle extension, according to a technical document produced by JAXA engineers.

Engineers say the open expander cycle, only used on upper stage engines up to now, allows the rocket engine to have a simpler design, reduces pressures and temperatures inside the engine, decreases heat on the turbines of the turbopump, and makes the engine more robust to failures.

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Japan moves forward with replacement for H-2A rocket