Participants developing a new dedicated ADS-B satellite constellation are also working to design and demonstrate an aircraft tracking system which is independent of positioning satellites.

French aerospace firm Thales and the US specialist Spire Global are aiming to put a constellation for space-based ADS-B into service by 2027.

But the companies have indicated that they will also co-operate on a parallel project to demonstrate the capability to determine aircraft position without relying on global navigation satellite systems such as GPS.

Concerns over potential jamming of GPS and other navigation signals, particularly in regions of conflict, are driving the project.

Thales and Spire Global state that the intention is to demonstrate a robust system to track aircraft which “cannot be impacted” by GPS interference or unavailability.

“The expected follow-on of a successful demonstration will be the commercialisation of a second generation, highly resilient service,” they add.

Washington-based Spire, through its German arm in Munich, has already initiated work on an potential independent air traffic monitoring system through a project called Eurialo.

Eurialo-c-Spire Global

Source: Spire Global

Eurialo would demonstrate aircraft position determination based on multilateration techniques

The Eurialo test platform is envisaged as comprising four small low-Earth orbit satellites and a ground station.

It would use a method known as multilateration to determine an aircraft’s position, calculating its location by analysing how the same signal transmitted from an aircraft is received by multiple satellites.

Multilateration is already used as a surveillance technique at airports, with variously-placed sensors detecting aircraft transponder signals and using them to ascertain position.

German aerospace research centre DLR is a key participant in the Eurialo project. It says the long-term aim is to use satellites to “fill the gaps” in conventional ground-based tracking.