What Is Space-Track.org? US Space Force Satellite Catalogue

📘 Definition

Space-Track.org is the public-facing interface to the US Space Command satellite catalogue, operated by the 18th Space Defense Squadron (18 SDS) at Vandenberg Space Force Base. The site provides Two-Line Element (TLE) orbital data, conjunction (close approach) warnings, launch notifications, decay predictions, and satellite metadata for over 47,000 tracked objects. Registration is free but requires acceptance of a data-sharing agreement. TLE data is updated multiple times per day as ground-based radars and telescopes observe each object. Orbital Radar fetches TLE data from Space-Track every 8 hours to power the live globe, pass predictions, Doppler correction, and the propagation heatmap.

18th Space Defense Squadron

Operator

47,000+

Objects Tracked

TLE (GP), OMM, TIP

Data Format

Multiple times daily

Update Frequency

Understanding Space-Track

What Data Does Space-Track Provide?

The primary dataset is General Perturbations (GP) orbital elements — the TLE format used with SGP4. Space-Track also provides Orbit Mean-elements Messages (OMM) in XML/JSON, Tracking and Impact Predictions (TIP) for decaying objects, conjunction data messages (CDM) for close approaches, and launch notifications. All GP data is publicly available; CDM access requires operator credentials.

Space-Track vs CelesTrak

CelesTrak is a popular mirror that redistributes Space-Track TLE data with additional categorisation and supplementary data. Orbital Radar uses both sources — Space-Track as the primary TLE source and CelesTrak for satellite categorisation and supplementary orbital data. Both are credited in the footer of every page.

How Orbital Radar Uses Space-Track

Every 8 hours, Orbital Radar fetches the complete active satellite catalogue from Space-Track. The TLE data feeds the SGP4 propagator that powers all live tracking, pass predictions, Doppler correction, and conjunction monitoring. See the data sources page for the complete data pipeline.

Frequently Asked Questions

Is Space-Track free to use? ▼

Yes — registration is free and open to anyone. You need to provide a valid email address and agree to the data-sharing terms. No government or military affiliation is required.

How often are TLEs updated? ▼

Most active satellites receive updated TLEs several times per day, depending on how many radar and optical tracking passes the Space Surveillance Network captures. Debris objects are updated less frequently — every few days. The more recently a TLE was generated (closer to its epoch), the more accurate the SGP4 position prediction.

Does Space-Track track everything in orbit? ▼

The US Space Surveillance Network tracks objects larger than about 10 cm in LEO and 30 cm–1 m in GEO. This accounts for roughly 47,000 objects. Millions of smaller debris fragments (1 mm – 10 cm) are statistically modelled but not individually tracked. The debris statistics page shows the full breakdown.