October 15, 2012

Bradley Perrett Nagoya, Japan

It might be called an aerospace wrinkle in the problem of Japan's aging population: the impending retirement of a cohort of engineers who have experience in developing large space launchers. If the Japanese government does not act soon, these people will be playing leisurely rounds of golf while their successors struggle to relearn old lessons.

With that in mind, Mitsubishi Heavy Industries is urging the government to move immediately on developing a new family of space launchers. While other countries might shrug off the problem and just make do indefinitely with current equipment, Japan is in a less comfortable position, because its H-IIA and H-IIB rockets are notoriously expensive to launch. Moreover, those two launchers are caught in an economic trap: Their costs are so high, especially once yen are converted to dollars, that they can rarely be used commercially, so the production and launch infrastructure behind them cannot be worked fast enough to drive down those expenses.

Mitsubishi Heavy, which builds and operates the launchers mainly for the government, does have plans to improve the H-IIA, however, partly addressing limitations imposed by launches from Tanegashima, an island much farther from the equator than competing launch sites.

The Japan Aerospace Exploration Agency (JAXA) has previously outlined plans for the replacement launcher family, H-X, which would be based on the LE-X engine (AW&ST Aug. 8, 2011, p. 52). The agency has promoted the family's modularity as offering lower costs. These need to be halved, says the senior general manager of Mitsubishi Heavy's space systems business, Shoichiro Asada.

Japan needs to use the H-IIA and H-IIB four times a year to provide enough work for suppliers to be profitable, according to the company's calculations, although Mitsubishi Heavy itself can cope with a lower rate because it is a big business with the flexibility to move staff between divisions.

Asada also points to two further requirements for the new system. One would be shorter periods between booking and executing a launch. For the H-IIA, that is currently 1.5 years.

The second improvement would be to vibrate the payload less than other rockets do, easing design satellite requirements or improving reliability. Space launchers shake their payloads severely due to engine noise, aerodynamic effects and the impulse from the separation mechanisms. The H-IIA does that at least as much as its competitors, says Asada, adding that a new family would improve in all three areas.