The U.S. Traffic Coordination System for Space and the European Union Space Surveillance and Tracking system demonstrated operational information exchange in a joint study published through the 2026 AMOS conference. The U.S. Office of Space Commerce reported the findings on October 7. The work examined why two services can issue different warnings about objects moving through the same orbital environment.
During the analysis period, TraCSS published approximately 45 times as many conjunction events as EU SST. It issued conjunction data messages for 65% of the 1,432 events published by the European service. The researchers attributed much of the difference to data selection and publication thresholds. The figures describe the services’ outputs, rather than a ranking of their accuracy.
In geostationary orbit, 95% of events appearing only in TraCSS fell below EU SST’s general publication thresholds. Other differences involved which orbital data sources each service used. The study identified a specific follow-up: checking whether relevant orbital predictions were being received and screened by both systems.
A conjunction is a predicted close approach between objects. Estimating its risk requires a prediction of each object’s motion and an assessment of uncertainty in those predictions. A warning can change when new observations improve the estimated orbit. An operator then evaluates whether additional tracking, coordination, or a maneuver is warranted.
New Space Economy’s explanation of international traffic coordination describes why common formats matter. Messages must identify the affected spacecraft and convey encounter information in a form that operational software can process. A team receiving information from several providers needs to compare equivalent events without treating every difference in message volume as a difference in physical danger.
The institutional purpose of TraCSS is also defined. The Office of Space Commerce is developing it to provide basic space situational awareness data and services to civil and private operators. Its October 2026 program information lists 87 pilot user organizations representing more than 11,380 satellites, together with 12 national government accounts.
National government accounts and satellite-operator accounts serve different users. The October figures describe participation in the service. The exchange with EU SST examines a separate function: whether two providers can compare and reconcile their operational information.
The study’s practical contribution is a way to identify discrepancies at their source. Matching the orbital inputs and understanding publication rules allows analysts to distinguish an omitted encounter from an encounter that another service intentionally does not distribute. That distinction helps spacecraft operators interpret warnings and supports more consistent information exchange.
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