Galileo Open Service Definition Document version 1.2 now available for download

The “Galileo - Open Service - Service Definition Document” (Galileo OS SDD) defines the Minimum Performance Levels (MPLs) of the Galileo Open Service (OS). Find out what billions of users of Galileo can expect.


The European Union Agency for the Space Programme (EUSPA) together with the European Commission announce the publication of the latest version of the Galileo Open Service Definition Document (OS SDD). The Galileo Open Service Definition Document (OS SDD) was updated on November 2021 to reflect upgrades in the Galileo system since the publication of the previous version in May 2019. The latest version, 1.2, can be found on the GSC web portal.

The SDD has been updated to include improvements of the Open Service, accounting for the current constellation and updates in the ground infrastructure that increase its robustness. This is the last update foreseen before Galileo Open Service reaches Full Operational Capability (FOC).

The updated SDD provides better Minimum Performance Levels (MPLs) for signal and position availability, updated definitions of some timing MPLs, and establishes a more stringent commitment on the time to publish Notice Advisories to Galileo Users (NAGUs). In addition, the concept of auxiliary satellites has been added, while some sections have been reworded to improve clarity.

Galileo Open Service Definition Document (OS SDD) at glance

As in previous versions, the main information in the SDD includes:

  • Service terms and conditions of use.
  • Service characteristics (scope, general concepts, assumptions, reference systems).
  • Service performance (Minimum Performance Levels and their associated conditions and constraints).
  • Annexes (providing further details on the parameters, expected performance evolutions, additional metrics and the description of NAGUs).


Users are invited to download and read the updated “Galileo Open Service Definition Document (SDD)” to discover the improvements of the Open Service and learn about its main characteristics and performance. For more details on Galileo performance and its services, please contact the Galileo Help Desk. Moreover, to receive NAGUs and notifications of new Galileo publications, please register to the GSC web portal and subscribe to our newsletters.

Media note: This feature can be republished without charge provided the European Union Agency for the Space Programme (EUSPA) is acknowledged as the source at the top or the bottom of the story. You must request permission before you use any of the photographs on the site. If you republish, we would be grateful if you could link back to the EUSPA website (http://www.euspa.europa.eu).