Trans. JSASS Aerospace Tech. Japan Vol. 10, No. ists28, pp. Tg_19-Tg_24, 2012 Topics Epsilon Rocket Launcher and Future Solid Rocket Technologies 1) 1) 2) By Yasuhiro MORITA , Takayuki IMOTO , Shinichiro TOKUDOME1), and Hirohito OHTSUKA 1) Japan Aerospace Exploration Agency (JAXA), Sagamihara/Tsukuba, Japan 2) IHI Aerospace Co.,Ltd.(IA), Tomioka, Japan (Received June 28th, 2011) The The Epsilon Epsilon rocket rocket, formerly, formerly called called Advanced Advanced Solid Solid Rocket Rocket (ASR) (ASR) launcher, launcher, proceeded proceeded to the to full the developmentfull development phase phase in in AugustAugust 2010 2010 and and its its launch launch site site was was officially officially declared declared to to be be the the Uchinoura Uchinoura Space Space Center Center (USC), (USC), the the home home of ofJapanese Japanese solidsolid propellant propellant rocket. rocket. The The primary primary purposepurpose ofof EpsilonEpsilon is toto provideprovide smallsmall satellites satellites with with a aresponsive responsive launch launch that that means means a a lowlow cost, cost, user-friendly user-friendly and and ultimatelyultimately eefficientfficient launch system.system. TheThe sloganslogan isis “ Small,“Small, Cheap, Cheap, Fast Fast and and Reliable Reliable”. ”.This This outcomeoutcome is isalso also a aresult result of of the the excellent excellent endeavorsendeavors of those whowho devoteddevoted themselves themselves to to the the next next generation generation solid solid propellant propellant rocket.rocket. However, However, this this is is not not the the final final destination.destination. Now that thethe developmentdevelopment was was approved, approved, the the most most important important is whatis what the the nextnext step step should should be be beyond beyond Epsilon. Epsilon. ThisThis paperpaper deals with thethe significancesignificance of of the the development development of of Epsilon Epsilon launch launch vehicle vehicle andand how how it itcontributes contributes to to the the possible possible evolutievolutionon of future space transportationtransportation systems. systems. Key Words: Solid Propulsion, Mobile Launch Control 1. Introduction transportation systems. The launch site of Epsilon was officially declared to be the Uchinoura Space Center (USC), The development of Epsilon rocket, Japan’s next the home of Japanese solid propellant rockets (Fig.1). generation solid rocket launcher, was formally approved by Originally, the Uchinoura Space Center was known for its Space Activities Commission (SAC) of Japan in August 2010, unique compactness, and it will be much more improved with four years after the M-V rocket launched its last payload. The a mobile launch control system. With this impressive Epsilon rocket, formerly called Advanced Solid Rocket (ASR) combination of a simple structure solid-fuel rocket and a launcher, is the successor to the M-V launch vehicle. The compact launch site, the Epsilon will undertake missions to SAC recognized the advantages of combined power of small reduce the threshold of access to space for everyone. satellites and the autonomous launch system. SAC further Now that the scope of the development has been defined declared that the Epsilon’s first flight will be conducted in and the full-scale development has been approved, the most 2013 to carry the planetary telescope satellite SPRINT-A. The important is what the next step should be beyond Epsilon. purpose of the Epsilon rocket is to provide small satellites JAXA proposes the post Epsilon development to launch the with a responsive launcher, which means in this study we low cost version Epsilon in 2017 based on the study on the focus on a low cost, user-friendly and ultimately efficient radically low cost technologies, primarily in avionics and launch system. 1-3 From the point of view of the space transportation research, it is most important to develop the next generation technologies for Epsilon such as the autonomous check-out system and the mobile launch control, which will make the Epsilon rocket far ahead of the world. Such innovative technologies will make the ground facilities and operations as compact as possible and will be applied to the H2A rocket as well and will eventually become the world standard after the development of Epsilon. In addition, the simplification of such launch control should be the technology that is indispensable to future reusable rocket systems. In this way, the concept of Epsilon rocket is beyond the scope of mere solid-propellant rockets. Rather Epsilon rocket aims at achieving the innovative transportation technologies that can be equally applicable to liquid fuel rockets as well as future space Fig. 1. Artistic view of the flight of Epsilon rocket, which is expected to be launched in 2013. Copyright© 2012 by the Japan Society for Aeronautical and Space Sciences and ISTS. All rights reserved. Tg_19 Trans. JSASS Aerospace Tech. Japan Vol. 10, No. ists28 (2012) Epsilon development. The second generation Epsilon is planned to be launched in 2017. The idea and the scope of the study were also approved by SAC and the targeted launch cost is set at below US$30 million to be competitive in the world market. This chapter describes the first step Epsilon in details and the research on low cost technologies in the second step of development is referred to in the next section together with other Fig. 2. Two step development plan of the Epsilon rocket. possible next generation technologies. 2.2. Concept and configuration of Epsilon rocket structural systems, which are planned to be conducted in As an advanced version of the M-V rocket, the Epsilon parallel with Epsilon development (Fig. 2). The idea and the rocket launch vehicle has three special aspects in scope of the study were also approved by SAC and the development: the optimization of the rocket configuration, the targeted launch cost is set at below US$30 million to be reform of the launch system, and the enhancement of user competitive in the world market. friendliness. The first topic is related to the design of the In addition to the study that was conducted for the post rocket system. The M-V rocket was optimized virtually only Epsilon development, there must still be more effort to evolve in launch performance to tackle with the relatively small the Epsilon rocket and enhance the space transportation development budget in spite of strong demand for large launch technologies in the larger scale. Once the mobile launch capacity. In sharp contrast, the Epsilon rocket is optimized in control is realized in the Epsilon development using an launch performance as well as operation cost. intelligent check-out system, it will be considered natural that Generally speaking, it is not always easy because the intelligence of the rocket should be further enhanced by performance and cost are naturally two competing indexes. making even the flight safety control autonomous, which will The key to success is the idea of sensitivity to launch eliminate those expensive tracking facilities, making the performance. It should be recognized that the first stage motor tracking control system highly compact and mobile. Our is relatively expensive mainly due to its relatively large size attention should then be directed toward a revolution of while its sensitivity to the entire rocket’s launch capacity is manufacture that will convert the current large-scale and not so high. Thus it is reasonable to utilize the low cost but inefficient manufacturing processes to a much smaller scale medium-performance SRB-A, a side booster of the H-2A and higher utilization frequency. This is the dimension that we launch vehicle, as the first stage rocket. On the other hand, the hardly considered seriously until now, but it cannot be second and third stage motors have significantly high avoided to achieve lower-cost and more frequent space sensitivity to the launch performance though they are activities. This paper deals with the details of the development inexpensive due to their relatively small scales. Therefore, at of Epsilon and reveals its possible evolution. those stages, the high-performance third and kicking stage 2. Design Concept of The Epsilon Rocket motors of the M-V vehicle are utilized. In addition, their performance is planned to be further enhanced by making the The purpose of the Epsilon rocket is to provide small motor case lighter. As a result, the performance of the second satellites with responsive launch, which means a low cost and and the third stage motors of the Epsilon can be expected to ultimately efficient launch system. Throughout 50 years exceed that of the M-V launcher. Those extremely history of Japan’s solid rockets, the research was conducted high-performance upper-stage motors will produce as high only to increase the rocket performance. Now, for the first payload ratio of the entire launch vehicle as the M-V rocket time ever in history, the rocket requires an optimization of the despite utilizing a sub-optimal first stage motor to reduce the entire launch system, including the efficient launch operations cost (Fig. 3). and the compact ground facilities. This attempt will contribute As a result, the configuration of the advanced solid rocket equally to the possible evolution of the liquid rockets as well is taken to be a three-staged launch vehicle having an optional as future space transportation systems. upper stage engine for better orbit insertion precision and 2.1. Development plan of Epsilon rocket maneuverability, which may be propelled by conventional JAXA announced the two-step development of Epsilon hydrazine engine. The entire lift-off mass is approximately 90 rocket: as the first step of development, the target is to achieve ton with the total length and maximum diameter to be 24 m the next generation technologies such as the rocket and 2.5 m, respectively. Its launch capacity is two thirds of intelligence and the mobile launch control while minimizing that of the M-V rocket: 1.2 ton into a low earth orbit (LEO) the cost and period needed for development.