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The Forefront of Space Science

User-friendly Nontoxic Liquid Propulsion System with Future Potential-Paving the Way to a New Era of Space Transportation-
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Through these experiments we have acquired the information necessary for N2O/ethanol propulsion-system operation and its engine design. We are now conducting the design study of system engineering demonstration model in an attempt to develop a liquid kick stage to be installed on the next solid-rocket system (Fig. 3). We regard the ground-firing test of the model as the final step in our fundamental experiments started in FY2003. Once our proposal is approved, we will conduct the test in FY2007.

Figure 3
Figure 3. Conceptual image of N2O/ethanol propulsion-system engineering-demonstration model

Toward actual application (practical education/space transportation)

Next I would like to reconsider our program to date. Although the primary purpose of our research was to establish a “safe liquid-propulsion system that can be used for student education,” we cannot yet offer students this opportunity. One reason is that we gave priority to verify whether we could develop a practically operational propulsion system. As long as we create practical, tangible educational material for space engineering at ISAS, JAXA, we hope to offer material that first can actually fly and secondly is useful for development of space transportation systems or actual transportation. Even so, to those young to mid-level engineers, whose average age is early 30s, participating in the research (including Tsuyoshi Yagishita, Naohiro Suzuki, Hiroto Habu and the author), the research presented a valuable opportunity to deepen our understanding on a storable (partially low temperature) liquid rocket engine. In conclusion, we can say that the research already contributes to “practical space-engineering education for professional engineers.”

Figure 34
Figure 4. Application to reusable transportation system development (e.g., input to re-entry trajectory)

Five years have passed since we started this project and our specific targets have developed over time. In addition to our desire to contribute to the development of the ultimate futuristic transportation system (*3), we also started to anticipate the actual introduction of our system to near-future space-transportation systems. To be specific, the first candidate is JAXA’s next solid-rocket system as stated above. The next will be manned space-exploration vehicles that are actively progressing mainly in the U.S. Nontoxic propellant is a high-priority issue with manned system development. The N2O/ethanol propulsion system has great potential for such applications because it boasts not only safety but also storage benefits, low-temperature compatibility and expansibility. We have already started to list up problems for developing our system as manned space technology and the answers to those problems. Furthermore, in the development of the next-generation reusable space-transportation system, our system can be utilized as a storable liquid propulsion OMS (Orbital Maneuvering System) for orbital control (Fig. 4).

Our current target is to develop a flight model within the next five years based on the five years of basic research and, in the course of development, to conduct practical space engineering education. I hope that we will perform the world’s first experimental flight of a nontoxic, storable liquid-propulsion system. I believe that all our readers will support us.

(Shinichiro TOKUDOME)

Reference literature:
*1 Deluga, G. A., Salge, J. R., Schmidt, L. D., and Verykios, X. E., “Renewable Hydrogen from Ethanol by Auto-thermal Reforming,” SCIENCE, Vol. 303, pp.993-997 (2004).
*2 Tsuyoshi Yagishita, Shinichiro Tokudome, Hiroto Habu, Naohiro Suzuki, Yoshiyuki Tokunaga, Seiichi Yasuda, Toru Shimada, Yasuhiro Daimo, “Experiments of N2O/Ethanol Propulsion System: 2F14,” 50th Space Sciences and Technology Conference, JAPAN Society for Aeronautical and Space Sciences (2006).
*3 Shinichiro Tokudome, Hiroto Habu, Junichiro Kawaguchi, Hirohito Otsuka, Takayuki Yamamoto, "Proposal on Flying Test Beds for Air-Breathing Engine Researchs,” 5th Space Science Symposium, ISAS of JAXA, pp.400-403 (2005).

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