US Space Surveillance Network (SSN)
The primary global space tracking system, operated by the US Space Force's 18th Space Defense Squadron (18 SDS). The SSN comprises approximately 30 radar and optical sensor sites worldwide, including the Space Fence radar on Kwajalein Atoll. It maintains the definitive public catalogue of ~44,800 tracked objects (early 2026), distributing data via Space-Track.org.
EU Space Surveillance and Tracking (EU SST)
A consortium of European national agencies pooling radar and optical assets. Key contributors include France (GRAVES radar), Germany (TIRA radar), Spain (S3T optical), and Italy. EU SST provides independent European capability for conjunction warnings and re-entry predictions.
ESA Space Debris Office
Based at ESOC in Darmstadt, Germany. Maintains debris environment models (MASTER, DRAMA), coordinates collision avoidance for ESA missions, and publishes the authoritative Space Environment Statistics.
Commercial Providers
LeoLabs: Commercial phased-array radar network (sites in US, New Zealand, Costa Rica, Australia, UK) providing LEO tracking and conjunction services. ExoAnalytic Solutions: Global network of optical telescopes for GEO and deep-space tracking. Numerica: AI-driven astrodynamics and tracking. These companies are increasingly filling gaps in government tracking and offering faster, more responsive services.
Other National Programmes
Russia (ISON optical network, Krona radar), China (national SSA programme), Japan (JAXA SSA), India (ISRO NETRA), and Australia (SSA partnership with the US) all contribute to the global monitoring picture.