Understanding Space-Track
What data does Space-Track provide?
Space-Track publishes far more than raw orbital elements. Its catalogue is exposed through a documented REST API and a family of standardised message formats, each suited to a different job:
| Product | What it is | Typical use |
|---|---|---|
| GP / TLE | Mean orbital elements for one object | Orbit propagation with SGP4 |
| OMM | Orbit Mean-Elements Message (XML/KVN) | Machine-readable element exchange |
| CDM | Conjunction Data Message | Close-approach warnings |
| TIP | Tracking & Impact Prediction | Reentry time and footprint |
| SATCAT | Catalogue metadata record | Launch date, country, object status |
How the catalogue is built
Every entry begins as a sensor observation. The US Space Surveillance Network — a global mix of phased-array and mechanical radars (including the S-band Space Fence on Kwajalein Atoll) plus optical telescopes for higher orbits — feeds tracking data to analysts and automated processes at Vandenberg. Orbits are re-estimated and each element set is stamped with an epoch, the exact time it is valid for. Low-orbit objects are refreshed most often because atmospheric drag changes their mean motion from day to day, so a TLE more than a few days old drifts noticeably. Elements are meant to be propagated with the SGP4 model rather than read as instantaneous positions, and Orbital Radar re-publishes derived data through its satellite directory.
Who runs it, and the shift to civilian control
Space-Track is operated by the 18th Space Defense Squadron within the US Space Force's Space Delta 2. For over a decade the US military has provided orbital data and conjunction assessment warnings to operators worldwide as a free public service. That civil and commercial role is gradually moving to the Department of Commerce, whose Office of Space Commerce is standing up TraCSS (Traffic Coordination System for Space), a civilian traffic-coordination service that began phased beta operations in 2024 and expanded through 2025. The transition has been bumpy — a proposed FY2026 budget cut nearly defunded TraCSS before Congress restored the money — so Space-Track remains the authoritative catalogue, with routine conjunction screening for civil operators expected to shift to TraCSS over the coming years.