CALLISTO: on the design and development of a reusable first stage demonstrator

Abstract CALLISTO is a collaborative project between JAXA, CNES, and DLR, focused on developing and operating a scaled reusable vertical-takeoff vertical-landing rocket stage demonstrator. This initiative is a crucial step for advancing reusable launch vehicle (RLV) technology in Europe and Japan. Significant strides have been made during the recently completed phase C of the project, particularly in aerodynamic modeling, guidance, navigation, and control design, landing dynamics, and flight domain definitions. These advancements facilitate the development of future operational vehicles and provide insights applicable to other RLV projects. This paper provides an update on the design and development status of the CALLISTO vehicle. It outlines the program objectives, focusing on mission design, vehicle life cycle, and their distinctions from legacy expendable launch vehicles in Europe and Japan. Details of the flight test plan, including in-flight experimentation, are elucidated, demonstrating incremental progress toward acquiring key technology and preparing for high-energy missions. Furthermore, the paper offers an overview of the CALLISTO vehicle’s development status, highlighting key architectural features such as load-carrying structures, avionics, rocket propulsion system, flight control systems, and approach and landing system. It underscores the milestones achieved over the past years and the progress toward the first flights. With a flight test campaign to be performed at Europe’s Spaceport in French Guiana, the CALLISTO project signifies a crucial step toward enhancing launch system affordability, competitiveness, versatility, and sustainability. This collaboration among three space organizations highlights the importance of shared expertise in advancing RLV technology and preparing for the next generation of launch vehicles.