Development of Optimal Design Tool for Future Space Transportation Systems

Abstract

The Japan Space Exploration Agency (JAXA) has started development of a concept design tool called SEAT (Systems Evaluation and Analysis Tool) to assist in evaluating candidate space transportation system concepts and selecting promising concepts for further development. This paper describes the SEAT development objectives, development strategy, and present status. Design results of a partially reusable space transportation systems, a rocket plane single-stage-to-orbit (SSTO) concept and a two-stages-to-orbit (TSTO) concept, are also presented. These results indicate extending the design flexibility of vehicle configuration as future development strategy for SEAT. The results also show the differences between SSTO and TSTO ascent trajectories: in case of the TSTO, the role of the first stage is to ascend to high altitude, while the second stage then accelerates to orbital speed in the thin atmosphere to reduce fuel consumption. This indicates that research on permissible separation conditions is required.