The European Space Agency (ESA) has become a strong proponent of using and contributing to open source software over the past decade. In 2012, the ESA formally adopted an Open Source Software Strategy to guide its involvement and investment in open source projects. The strategy outlines several key principles:
- Adopt open source solutions whenever possible: The ESA aims to use open source software as its first choice when selecting software for its projects and operations. This applies to both infrastructure software like operating systems and development tools, as well as application software.
- Release ESA software as open source: The ESA will strive to release any software developed internally as open source. This allows a wider community to benefit from ESA code and help improve it over time. Exceptions may be made for sensitive modules like flight software.
- Contribute actively to external projects: Beyond just using open source software, the ESA seeks to be an active contributor to external open source projects that are useful to its work. This ensures the ESA’s interests are represented in those projects.
- Encourage open source skills development: ESA staff are encouraged to participate in open source projects in their free time to gain valuable skills and grow the agency’s in-house expertise. Educational materials are provided to support this.
- Favor open source in procurement: When contracting external vendors, the ESA gives preference to solutions that include open source components and open up custom modules developed for the ESA.
To help achieve these goals, the ESA has launched several initiatives:
- ESA Open Source Software Repository (https://essr.esa.int/): This online repository hosts various open source software projects started at ESA. Topics range from data analysis tools to flight dynamics libraries.
- Earth Observation Open Science Portal (https://eoscience.esa.int/): This web platform provides open access to software, tutorials, and reference data for Earth observation research. Key projects shared include snap, Sentinel Application Platform, and ESA WorldCover.
Over the past decade, the ESA has shared dozens of key software projects and tools under open source licenses. By embracing open collaboration, the agency aims to accelerate space research and lower barriers for new participants worldwide. The ESA’s open source policy has provided benefits within the agency and to the broader scientific community.