A live test with operational satellites
For two hours on the afternoon of September 16, 2026, five Galileo satellites currently in active service transmitted an experimental encrypted signal across European airspace. This was not a controlled laboratory exercise: the same spacecraft that provide daily positioning for millions of civilian users were repurposed for the trial. The goal was to demonstrate, under genuine operational conditions, the readiness of Galileo's forthcoming Signal Authentication Service, known as SAS.
Two ground stations took part in the exercise. One was located in Andøya, Norway, offering a representative field environment. The other was set up at ESA's navigation laboratory inside the ESTEC research centre in the Netherlands. At both locations, purpose-built receivers successfully computed their position using only the authenticated signal — marking the first time civil GNSS receivers have achieved a verified position fix under deliberate spoofing conditions in the real world.
Spoofing: a growing threat to civil navigation
GNSS spoofing involves broadcasting counterfeit navigation signals that trick a receiver into calculating a false position. The technique has evolved from a niche security concern into a documented operational hazard. Ships have reported phantom position shifts near contested maritime zones. Drones have been redirected. Autonomous vehicle systems have been destabilised. The frequency and geographic spread of spoofing incidents has increased markedly in recent years, affecting both military assets and civilian infrastructure alike.
The SAS architecture is designed to counter this threat at the signal level. Rather than relying solely on signal strength or timing — parameters that can be replicated by a spoofing transmitter — the authenticated signal carries a cryptographic signature. A SAS-capable receiver can verify that the incoming signal genuinely originates from a Galileo satellite in orbit, not from a ground-based or airborne emitter mimicking one. When authentication fails, the receiver flags the anomaly immediately, allowing downstream systems to react accordingly.
A civilian service, not a military privilege
One of the defining characteristics of the SAS is its intended user base. Unlike the encrypted signals already available on GPS — which are primarily reserved for military and government users — Galileo's authentication layer is being developed as a civilian service. That positions it as a tool for transport operators, port authorities, critical infrastructure managers, and potentially consumer electronics manufacturers over the longer term.
ESA has not yet published a firm timeline for the commercial rollout of the SAS. Further testing phases appear likely before any large-scale deployment, and hardware manufacturers will need to integrate SAS decoding capabilities into chipsets and receiver designs. Those are non-trivial steps that will take time.
Even so, the September 16 test moves the SAS from a theoretical specification to a demonstrated capability. Galileo, operated under the European Union's space programme, now has tangible evidence that authenticated positioning works in the field. In an electromagnetic environment that is increasingly contested — from the Baltic to the Middle East and beyond — that shift carries real weight for anyone depending on satellite navigation to make critical decisions.
