Creating a USB for more resilient, sustainable and efficient space infrastructure
Modern spacecraft are often equipped with proprietary service interfaces, preventing interoperability across missions, agencies or commercial entities. In this fragmented environment, a satellite designed with one interface cannot be serviced or assembled by another spacecraft using a different connector, making it difficult to develop a scalable, sustainable, serviceable and unified ecosystem for space communications and services. Launched in 2024, the EU-funded SPACE USB(opens in new window) project is addressing this issue by laying the foundations for a standardised, serial and universal connection system – a real universal serial bus (USB) for space exploration systems. Through the mechanical and electrical adapter, or common passive interface (CPI), it is developing, the project aims to allow mechanical coupling and data/power exchange between the three major European spacecraft service interfaces – HOTDOCK, SIROM and iSSI – without degrading their individual performance. “This effort is essential to unleash the full potential of on-orbit servicing, robotic assembly and modular spacecraft design, while reducing space debris and enabling a more circular space economy,” explains Matisse Briand, Sustainable Innovation Consultant at SPACE USB’s French project partner In Extenso Innovation Croissance. The CPI will also be symmetrical, compact and compatible with robotic arms and orbital replacement units. It will further pave the way for future universal standard interfaces that could become the backbone of interoperable operations involving satellites in different orbits.
Milestones in interoperability
To date, SPACE USB has achieved several key milestones that establish the groundwork for interoperability in on-orbit servicing. One is a comprehensive state-of-the-art survey that covered around 100 multifunctional interconnect solutions from Europe, the United States and Asia. HOTDOCK, SIROM and iSSI, as well as commercially available systems, were each analysed using over 70 technical criteria, including mechanical, electrical, thermal and operational properties. “This survey highlighted both the diversity of interface designs and the lack of convergence, reinforcing the need of a common standard,” notes Briand. Building on the survey’s findings, SPACE USB established a standardisation framework with defined mechanical symmetries, data protocols and power ranges to ensure cross-compatibility. The resulting set of reference specifications will serve as a baseline for future European and international interface designs. Significant progress has also been made in the CPI’s mechanical and electrical design. The project team is now finalising the TRL 4(opens in new window) prototype for robotic testing in the last quarter of 2025. SPACE USB has now entered its experimental phase, focusing on dynamic validation in a robotic test bed. The goal is to ensure mechanical interoperability under repeated docking/undocking cycles and alignment capabilities across different robotic arms, as well as electrical continuity and data integrity after mating/locking and connection. The SPACE USB (SPACE Universal Serial Bus) project’s CPI will enable competitiveness with multi-vendor compatibility and reduce mission lock-in and lower costs through modularity, reusability and reduced design constraints. It will also make missions more flexible and support the emergence of orbital ecosystems based on robotic assembly, plug-and-play payloads and sustainable infrastructure. Briand concludes: “Ultimately, SPACE USB is a cornerstone in Europe’s roadmap for in-space servicing, reinforcing the continent’s autonomy and leadership in orbital sustainability and innovation.” If you are interested in having your project featured as a ‘Project of the Month’, please send us an email to editorial@cordis.europa.eu and tell us why!