All satellites have a design lifetime after which their systems are expected to be less reliable or effective. For a constellation like the European Union's Galileo, which serves as a critical public infrastructure and aims to deliver uninterrupted services over decades, it is critical to retire older satellites to allow for new ones.

Once a year, Galileo partners assess the condition and contribution of older satellites and determine either to keep them running for another year or to retire them, bringing them to a higher and safer orbit and powering them down. This helps keep space clean, in line with ESA’s core commitment to reducing space debris.