Starlinks Spacemap
Real-time tracking of the complete Starlink mega-constellation using live TLE orbital data, SGP4 propagation, and WebGL globe rendering — 6,000+ satellites updated every 5 seconds.
~42,000
Approved satellites
~6,500
Currently deployed
5 primary
Orbital shells
~90 min
Orbital period
340–570 km
Service altitude
~7.6 km/s
Velocity
±90°
Coverage latitude
Yes
Laser ISLs (v1.5+)
Data Pipeline
From raw orbital mechanics data to animated WebGL positions in six steps.
CelesTrak TLE Feed
General Perturbation (GP) element sets for all active Starlink satellites fetched from CelesTrak (sponsored by AMSAT). Data conforms to CCSDS OMM v2.0 standard with NORAD-assigned IDs.
Next.js API Proxy
A server-side Next.js Route Handler proxies requests to CelesTrak, adds 10-minute edge caching, and handles CORS — keeping the client payload clean and the external API rate-limit safe.
TLE Parsing
Two-Line Element sets are parsed by satellite.js using the `twoline2satrec()` function, converting the compact TLE encoding into the numerical state vector required by the SGP4 propagator.
SGP4 Orbital Propagation
The SGP4/SDP4 algorithm propagates each satellite's state vector forward to the current UTC time, accounting for atmospheric drag, Earth's oblateness (J2 perturbation), and solar radiation pressure.
Coordinate Transformation
ECI (Earth-Centred Inertial) cartesian coordinates are converted to geodetic latitude, longitude, and altitude using Greenwich Mean Sidereal Time (GMST), giving real-world geographic positions.
WebGL Globe Rendering
6,000+ satellite positions and 90-minute ground tracks are rendered every 5 seconds on a globe.gl WebGL globe with NASA Earth-Night texture, topology bump map, and animated orbital path dashes.
Orbital Shells
Starlink deploys satellites across five primary orbital shells, each with distinct inclination, altitude, and coverage zone. The globe colours each satellite by its shell.
| Shell | Inclination | Altitude | Planes | Sats/Plane | Coverage |
|---|---|---|---|---|---|
| Shell 1 | 53.0° | 550 km | 72 | 22 | Original operational LEO shell. Provides global coverage between ±53° latitude. |
| Shell 2 | 53.2° | 540 km | 72 | 22 | Second 53° shell deployed to increase capacity density. |
| Shell 3 | 70.0° | 570 km | 36 | 20 | High-inclination shell extending coverage to ±70° latitude for polar regions. |
| Shell 4 | 97.6° | 560 km | 6 | 58 | Sun-synchronous retrograde orbit. Provides near-polar coverage and consistent solar geometry. |
| Shell 5 | 43.0° | 535 km | 72 | 22 | Gen 2 mid-inclination shell targeting high-density population corridors. |
Tech Stack
CelesTrak GP/TLE
Orbital data
satellite.js (SGP4)
Propagator
globe.gl + Three.js
Globe renderer
NASA Blue Marble Night
Earth texture
5 s position refresh
Update rate
10 min edge cache
TLE cache
Next.js 16 App Router
Framework
6,000+ Starlinks
Satellites
📐 What is SGP4 Propagation?
Simplified General Perturbations 4 (SGP4) is the standard algorithm used by NORAD and space agencies worldwide to predict satellite positions from Two-Line Element (TLE) sets. It models the effects of atmospheric drag, Earth's oblateness (J2–J6 harmonics), and solar/lunar gravity to propagate an orbital state forward in time.
Each TLE is valid for approximately 1–2 weeks before atmospheric drag introduces significant position errors. CelesTrak distributes fresh TLEs daily from Space-Track.org.
Two-Line Element set — compact orbital parameter encoding used by NORAD
Simplified General Perturbations 4 — orbit propagation algorithm
Earth-Centred Inertial frame — fixed reference frame used during propagation
Greenwich Mean Sidereal Time — rotates ECI to Earth-fixed ECEF frame
Drag coefficient in TLE encoding representing atmospheric drag decay
Data Sources
CelesTrak
TLE data provider
Distributes NORAD/Space-Track GP element sets. Free public API with GP JSON endpoint for active satellites.
Space-Track.org
Authoritative source
US Space Force 18th Space Control Squadron — the authoritative source of all NORAD catalog TLE data.
NASA Blue Marble
Earth imagery
NASA's Earth at Night composite satellite imagery used for the globe texture in globe.gl.
See it live — 6,000+ satellites right now
Open the interactive globe to explore the full Starlink constellation in real time, filter by orbital shell, and track individual satellites.
🛰️ Launch Spacemap