Advanced Solid Rocket Motors

T challenge to explore space was the main reason to develop highperformance propulsion systems. Although initially developed for military purposes, solid rocket motors (SRM) were adapted to space launchers after reaching a suffi cient level of technology maturity and thus also of reliability. At this time all U.S., European Union (EU), and Japanese launchers combine core liquid rocket propulsion with SRM-powered boosters, the latter providing most of the thrust needed at takeoff. Solid-rocket-motor technology is well known (in EU the most advanced product is the two-SRM booster system powering Ariane 5 at launch (Fig. 1), whereas in the United States it is the shuttle booster system). Thus in the EU the main purpose in solid-rocket-propulsion research and development for commercial launchers is to improve present technology with the main objective to achieve substantial savings in all industrial phases, from development to production. In the United States the focus is on the Ares 1 crew launcher for the return to the moon future mission, which will consist of a stack of segment modules from the shuttle SRM. In Europe this cost-reduction process already started with the ESA-driven P-80-FW and MPS 2010. Together with cost, a second goal is to improve Ariane’s