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,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(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.
Building that family will require funding, but Mitsubishi Heavy says the government should move while it has the advantage of a highly experienced workforce. About a quarter of Japan's space engineers—those who have had the most experience developing the H-II series and its predecessors—will retire by 2020, Asada said at the Japan International Aerospace Exhibition here last week. By 2020, an engineer who was 25 in the mid-1980s, during early work on the original H-II rocket, will be around 60.
So 2020 should be the target date for the entry into service of the H-X, Mitsubishi Heavy has told the government. JAXA has also designated 2020 as the target for flying the first H-X. Since development would take 6-8 years, there is little scope for delay.
Mitsubishi Heavy has handled H-IIA launches since 2007; JAXA conducted them before then.
Putting production and operation in the hands of one company would theoretically save money, and Mitsubishi Heavy did indeed simplify and improve the process, says Asada. Since the company was using the rockets itself, it could reduce the number of inspections. Now H-IIAs are checked just once. In another rationalization, design and development engineers follow each rocket from production to launch—it is not necessary to have completely separate teams for each phase.
Costs have not fallen, however, says Asada. In fact, they are a little higher than before, because each launch has resulted in demands to refine the H-IIA design. But costs would have been even higher had the government not given the launch work to Mitsubishi Heavy, he says. The government is evidently satisfied with the company's performance, because it has now decided to contract it to launch the heavier H-IIB rocket. Asada does not expect expenses to fall, though, and he declines to say why the government made the choice.
The H-IIA's payload is limited by the location of Tanegashima, which demands a greater impulse for orbital speeds (since the radial velocity of the Earth there is lower than at the equator) and because a high launch latitude results in an orbit with an equally high angle from the equator. In its standard H2A202 version, with two boosters, the H-IIA can lift 4 tons to this skewed geostationary transfer orbit. The satellite, on reaching the farthest point, must then burn an unusually large amount of fuel to reach the properly aligned geostationary track, adjusting its velocity by 1,830 meters per sec. (6,000 fps.). Customers are reluctant to accept that demand.
So Mitsubishi Heavy is working on an adaptation of the H-IIA, with a second stage that would remain with the satellite until it reached that distant point, coasting all the way, and would then fire again to correct the orbital inclination. The satellite would then need only to change its velocity by a more typical 1,500 meters per second to reach geosynchronous orbit. The modified rocket could deliver a 2.9-ton satellite in that manner but, for it to do so, the designers must minimize evaporation of the hydrogen fuel of the second stage during the 5-hr. coast. Asada says that applying a reflective white coating to the fuel tank, to keep the hydrogen cold, will help. The modified rocket will also need more electrical battery capacity and its thrust would have to be throttled.
H-IIAs and H-IIBs are used almost exclusively for Japanese government payloads, but in May the H-IIA performed the first mission for which it competed in the open market, launching a South Korean government satellite.
Asada says that apart from the modification to the second stage, one more change is needed for the H-IIA to again win such orders: a more favorable currency exchange rate. If the dollar were worth ¥100 the rocket would be competitive, he says. The dollars recent value has been around ¥78.
The H-IIB was built mainly to launch Japan's HTV Kounotori cargo craft to the International Space Station. With a cheaper yen, it could compete commercially, says Asada, by launching two satellites at a time, one of which might belong to the Japanese government.
The next H-IIA mission will be to loft a military reconnaissance satellite. The date has not been disclosed.