The recent debut of China as the world's third human spaceflight power adds more impetus for change. For the United States and Russia, our planet's traditional leaders in human spaceflight, the flight of Yang Liwei in 2003 did not produce much shock. Certainly, these nations were impressed by China's achievement, but the flight does not seem to have prompted panic, or any change in the way their space programs operate.
The reaction in Japan would seem to be less benign. Japan prides itself on its economic and technological strength, yet its recent track record in spaceflight does not compare favourably with China. Soon after China had launched Shenzhou 5, Japan lost another rocket. Rumblings in the Japanese media, and some segments of the international aerospace media, suggest that there is growing interest in developing a Japanese human spaceflight capability in the near future.
How could this be done? At the time of writing, no specific plans for a Japanese crew-carrying spacecraft have been published, and no such program has even received formal approval. But a crash program could be designed around existing Japanese space hardware, and hardware that is almost developed.
Japan's previous efforts to develop crew-carrying spacecraft have focused on winged spaceplanes. Models have been tested around the world, and research has also been conducted with France. But such a spacecraft would be complex, costly and would take a long time to develop. It would be more prudent for Japan to pursue a capsule-style design, which could produce a robust spacecraft in a modest interval.
A capsule spacecraft must be tailored to fit its launch vehicle. In this case, the only vehicle Japan could task for such a mission is the H2A. This rocket has enough lifting capacity to place a heavy vehicle into a useful low orbit. It is already operational. But H2A has the serious disadvantage of poor reliability. No engineer would declare it "man rated" on its current performance record. So any first steps in a Japanese space capsule program would need to focus on improving the safety of this rocket.
One obvious modification for man-rating H2A would be the deletion of its solid rocket boosters. Admittedly, the vehicle would suffer a serious loss in its lift capacity, but the reliability would be improved. A failure in the separation of one SRB caused the most recent failure of H2A.
In any case, solid motors are difficult to control after ignition. But H2A will require extensive tinkering and testing of all its sub-systems. Such reviews will take place for the benefit of H2A's uncrewed missions, but the possibility of human missions makes this even more important.
A reliable crew escape system, similar to the ones used on Soyuz and Shenzhou, would be essential. H2A could also benefit from fins to stabilise the aerodynamic influences of this new hardware.
- Spacedaily.com
http://www.spacedaily.com/news/spacetravel-04b.html
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Japanese Space rockets:
