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Japanese Rocket Technology Advances
Space Exploration

Part 2

Japanese Technology Advances Space Exploration

H-IIA (left, height: 53 m) and H-IIB (right, height: 56.6 m); liquid-fuel rockets equipped with solid-fuel boosters

H-IIA (left, height: 53 m) and H-IIB (right, height: 56.6 m); liquid-fuel rockets equipped with solid-fuel boosters ©JAXA

Stemming from the early era of space exploration during the 1960s, another branch of rocketry focused on the development of liquid-fuel rockets. While solid-fuel rockets can be constructed more easily, their speed and course are difficult to control. Liquid-fuel rockets offer more reliable control and are more suitable for launching commercial satellites such as communications and weather satellites.

Japan became the third country in the world to launch a geostationary satellite in 1977 with the Kiku-2, launched with the liquid-fuel N-I rocket. Subsequent work to improve launch performance, fuel costs, and satellite control led to the H series rockets. The H series built upon all the technologies developed in Japan's line of solid-fuel rockets, from the Pencil to the M-V. The H-IIA was a liquid-fuel rocket equipped with solid-fuel boosters, a design that provided more stable performance and a lower production costs.


Akatsuki Venus space probe (left) and Ikaros interplanetary space probe (right). They were launched together on a H-IIA rocket in 2010 ©Akihiro Ikeshita (left), ©JAXA (right)

In 2007, the H-IIA rocket was used to launch Kaguya, a satellite that orbited the moon; in 2010 it launched the Akatsuki Venus space probe together with the Ikaros interplanetary space probe. Ikaros is in fact an advanced space yacht. It has an extremely thin solar sail, equipped with film batteries, which opens up in space to generate power and propel the craft. It is the world's first successful experiment in space travel using a solar sail. The next goal is to launch a larger space yacht bound for Jupiter. As of 2011, the H-IIA rocket has achieved a remarkable 95% successful launch rate.

The H-IIB rocket, an upgraded version of the H-IIA rocket which launched the HTV Kounotori, is scheduled to launch seven more HTV supply vehicles to space stations to provide support for a range of experiments and research in space. So, beginning with the Pencil rocket, Japanese rocket development and space exploration has led to the creation of a space yacht, and the country's rockets are now relied upon to transport supplies to the ISS. Japan will continue to work on rocket development that further advances the exploration of space.

Moon surface, HTV Kounotori

Left: Moon surface captured with a high-definition telephoto camera on Kaguya, a satellite that orbits the moon ©JAXA/NHK
Right: HTV Kounotori docking with the ISS ©JAXA/NASA

(Updated in February 2012)