The European Space Agency has issued a call for proposals for the second phase of its Reusable Upper Stage Demonstrator project.
Initially announced in March 2024, the Reusable Upper Stage Demonstrator project is being managed by ESA’s Space Transportation Technology Coordination Office under the agency’s Future Launchers Preparatory Programme (FLPP). The FLPP initiative focuses on developing and maturing critical technologies for future European rockets, as well as upgrades for existing launch systems.
Work on the project’s first phase began in the second half of 2024 and focused on identifying the technology maturation needs for a reusable upper stage demonstrator. This phase also included an assessment of potential commercial applications for the technology.
On 15 May, ESA published a call for proposals for Phase 2 of the project, which will focus on activities “up to a critical design milestone.” This stage in a project’s development typically signifies that the detailed design is complete and the system is ready to proceed to manufacturing or full-scale implementation. While the call did not provide much additional detail, it does note that Phase 2 will involve early long-lead technology maturation and demonstration activities.
While ESA continues to advance the Reusable Upper Stage Demonstrator project, it has not made any public announcements regarding the companies involved in Phase 1. It also remains unclear whether the technology could be integrated into the Ariane 6 launch system or whether, like Themis, the project is intended solely to lay the groundwork for future launch vehicles.
ESA is not the only European space agency pursuing a reusable upper stage. Earlier this year, the French space agency CNES published a call for proposals for its DEMESURE project (DEMonstration Étage SUpérieur REutilisable / Reusable Upper Stage Demonstration). The project aims to develop the technology for a reusable upper stage for a two-stage launch vehicle capable of delivering up to 20 tonnes to low Earth orbit, which is comparable to Ariane 6. However, the initial demonstration will be conducted at a reduced scale.
