Launch Vehicles

Japan has a history of high level of rocket technology awareness from the time before the end of the Second World War, but it was not put in use by the country after the war. Subsequently, only by 1950s, Japan started taking interest in rocketry technology. A tiny rocket ‘Pencil’ was launched horizontally at Kokubunji near Tokyo in 1955 [7]. This could be said to be the first entry of Japan in the field of rocketry in post-World War II era. Over the years, Japan has been developing its own launch vehicles, mainly based on indigenous research and development.

Based on the research and development initiated by Professor Itokawa during 1954-1956, the Kappa series of sounding rockets were developed at Tokyo Uni­versity. These rockets were named as Pencil and Baby. The most advanced Kappa rocket (1966) could carry an 18-kg scientific package to a height of 746 km. During 1960s scaled-up versions of the solid-propellant Kappa sounding rockets were put in use called Lambda, or L series rockets. Also, Mu series rockets were developed with an aim of putting first Japanese satellite in place. However, subsequently Lambda series L-4S rocket was used to put the first Japanese satellite (Ohsumi) in orbit on Feb. 11, 1970 [8]. Other developments include the M series, the N series, H series andJ-1 series.[113]

M-V rocket also called as Mu-5 or M-5 was from the Mu family of rockets. This satellite launcher was developed to support Japanese scientific missions beyond late 1990s. It is a three-staged solid-propellant rocket with a 1.8-ton launch capability into 250-km LEO. The first two flights were successfully launched in 1997 and 1998, but the third lunch failed in Feb. 2000[114]. Subsequent three launches were successes, and the last launch was undertaken during 2006. This rocket has potential

for being converted to ballistic missile applications.[115] After six successful launches in a span of 9 years, these launchers retired in 2006.

The N series (N-1, N-2) rockets entered in service during mid-1970s and 1980s. The N-2 vehicle was manufactured to place 350 kg load into geostationary orbit. The entire process of development and manufacture of various launchers had US support behind it. Boosters and engines were manufactured in Japan under the US license, and various components and guidance systems were procured from the US firms [9]. Japan’s first remote sensing satellite was launched with the help of the N-2 booster in 1987 which incidentally was the last launch for this series of boosters.

The limited payload capability of N-series launch vehicles forced Japan to develop platforms capable of putting higher payload in to the orbit, and thus during 1980s, it started the development of H series launchers. Also, one of the aims was to achieve indigenous launch capability potential. With the help of H-1 launcher by 1986, Japan succeeded in putting 1,110 kg payload into the geosynchronous transfer orbit (GTO). However, they depended on US technology for this launch too.

Subsequently, Japan started the work on H-2 launcher with an aim to put 4,000-kg satellite into GTO. Also, Japan was interested in making its satellite programme commercially viable. Since Japan was concentrating for the production of an indigenous launcher, the project got delayed, and first launch could take place only in 1994. H-2 rocket conducted five successful launches during 1994-1997. Subsequently, it faced two failures, and in December 1999, Japan decided to cancel the last remaining launch. The problem was identified with the indigenous develop­ment of cryogenic engine. Understanding that H-2 cannot become a commercially viable launcher, Japan shifted its focus towards H-2A launchers [5].

H-2A launcher could be said to have reassured the Japanese scientific community about their capabilities. With its first launch in August 2001, this launcher had done 14 successful launches (out of 15) till 2009. This launcher can be in various configurations and is designed to meet diverse launch demands, at lower cost and with a high degree of reliability.[116] The same launcher was used on September 14, 2007, for launching Japan’s Moon orbiter SELENE. The launcher was also put in use to deliver a foreign payload (Australia, 2002). The only setback this launcher had was its failure to put two Japanese spy satellites into the orbit during November 2003. This launcher system has undertaken various successful launches, and in 2010, the Venus Climate Orbiter was also launched using their services. Presently, H-2A launch service operations have been transferred to Mitsubishi Heavy Industries. Japan has also developed the H-2B launch vehicle. This is an upgraded version of the H-2A launch vehicle. With the help of this launcher, Japan as successfully launched a cargo transporter to the International Space Station during January 2011.[117] Now, with two operational launch systems available, it would

allow Japan to undertake a simultaneous launch of more than one satellite. This would also offer other benefits like reduction in cost and boosting the space industry.