If it is important to have the right tools for the job, then if the job changes so must the tools. Since the size of Japan's satellites is evolving away from the capabilities of its current launchers, the country's space agency is drawing up plans for a new family of medium to heavy rockets. The Japan Aerospace Exploration Agency (JAXA) also thinks it can build launchers that are cheaper than its H-IIA workhorse. And the requirement for new development is emerging as the country moves toward its first manned space missions (see p. 48).

It is not easy to persuade scientists to let you try out your fancy new engine on their spacecraft. What if it fails? Tens of millions of dollars of instruments will float uselessly in space or burn up in the atmosphere. But until the Japanese engineers developing a rocket engine fueled by liquefied natural gas (LNG, mostly methane) find a host spacecraft, they will not be able to demonstrate the reliability required to go along with its expected performance advantages.

Among JAXA's major space transportation development programs, the one with the most assured future is the Epsilon, a solid-propellant rocket that is now well into the detailed design phase and is due for a first launch in 2013.