What is GROUNDTRACK?
GROUNDTRACK is a real-time 3D satellite tracking platform. It shows the live positions of real satellites orbiting Earth, computed using actual orbital data (TLEs) and the SGP4/SDP4 propagation model — the same algorithm used operationally by space agencies.
You can track satellites across three orbital regimes, add ground stations to see which satellites are in view, travel through time to see past and future positions, and search for any satellite in the CelesTrak database by name.
Quick Start
- Rotate globe
- Click and drag on the globe
- Zoom
- Scroll wheel · or use + / − buttons
- Select satellite
- Click any satellite dot on the globe or in the side list
- Deselect
- Click the satellite again · or click empty space · or press ✕ BACK
- Search satellite
- Type in the search box — local filter first, then CelesTrak if not found
- Add ground station
- Click ⊞ to load defaults · or ＋ then click anywhere on the globe
- Travel in time
- Drag the timeline scrubber at the bottom of the globe
TIP — Satellite positions update in real time every frame. The day/night terminator on the globe is also astronomically accurate — it reflects the real current sun position.
Data Source
Orbital data comes from CelesTrak (celestrak.org), a free public source maintained by Dr T.S. Kelso. TLEs are cached for 4 hours to avoid hammering the server. A set of 18 validated satellites is baked in so the tracker works offline or in sandboxed environments.
Rotating the Globe
Click and drag anywhere on the globe to rotate it. On mobile, touch and drag works the same way.
Zooming
- Scroll wheel
- Scroll up to zoom in, down to zoom out. Step size is proportional to current distance — finer when close, coarser when far.
- + / − buttons
- Fixed-step zoom buttons in the bottom-right corner of the globe.
- Following a satellite
- When a satellite is selected, zoom minimum drops to very close range so you can inspect it up close. Deselecting snaps back to a safe globe distance.
What You're Seeing
The Earth texture is NASA Blue Marble imagery — actual satellite photography composited into an equirectangular map. The night side shows NASA Black Marble city light data. The day/night boundary updates in real time based on the actual sun position.
The thin cloud layer rotates slightly slower than the surface — a subtle parallax effect suggesting real cloud drift.
The atmospheric glow around the globe is a purely visual addition to give a control-room feel.
TIP — Zoom out fully to see all orbital shells at once: LEO satellites close to the surface, MEO (GPS/Galileo) in the middle ring, GEO satellites as a nearly-stationary ring far out.
Satellite Icons
Each satellite is shown as a small icon resembling a real satellite: a rectangular body, two solar panel wings, and a parabolic dish antenna. They always face the camera (billboard sprites) so they're readable from any angle.
Orbit Regimes & Colours
Default (not in any ground station cone) In view of a teal-coloured ground station In view of an orange ground station
Satellites are white by default. When they enter a ground station's visibility cone, they change to that station's colour — making it instantly clear which satellite is currently accessible from the ground.
Orbit Regime Filter
- ALL
- Show all satellites regardless of orbital shell
- LEO
- Low Earth Orbit — altitude below 2,000 km. ISS, weather sats, Starlink, Earth observation.
- MEO
- Medium Earth Orbit — 2,000–35,000 km. GPS, Galileo, GLONASS navigation constellations.
- GEO
- Geostationary Orbit — ~35,786 km. Appears nearly stationary. Weather and communications satellites.
Selecting a Satellite
Click any satellite dot on the globe or any item in the side panel list. The camera smoothly pans to centre the satellite in view and the pivot point shifts to the satellite — so dragging now orbits around it. You can zoom in very close to inspect it.
The orbit path is drawn as a coloured ring showing one full orbital period into the future from the current moment.
The detail panel shows: satellite type and regime, current altitude, orbital inclination, orbital period, and live lat/lon position (updated each second).
The name label follows the satellite on the globe and changes colour to match the ground station's colour when the satellite is in view of one.
Deselecting
- Click satellite again
- Toggles selection off
- Click empty globe space
- Deselects and returns camera to globe-orbit mode
- ✕ BACK button
- In the detail panel — deselects and clears search
TIP — GEO satellites (GOES, Intelsat etc.) barely move relative to the globe. If you select one and zoom in close, you can watch the Earth rotating beneath it while the satellite stays almost perfectly fixed in space.
What Ground Stations Show
Each ground station displays a semi-transparent coloured cone extending from its location on the globe surface outward into space. The cone angle represents the station's visibility mask — satellites inside the cone are above the minimum elevation angle and can theoretically communicate with the station.
The cone geometry is physically correct: a 5° minimum elevation angle produces an 85° half-angle cone, covering almost the full hemisphere above the horizon.
Loading Ground Stations
- ⊞ Load defaults
- Loads 8 real ground stations: ESA ESTRACK (Kourou, New Norcia, Malargüe), NASA Deep Space Network (Goldstone, Madrid, Canberra), and NOAA (Svalbard, Fairbanks).
- ＋ Add custom
- Activates placement mode (cursor changes to crosshair). Click anywhere on the globe to place a station. A prompt asks for the station name.
Managing Stations
- Click station row
- Selects the station — camera pans to its location, detail panel shows agency, coordinates, altitude, elevation mask, and live visible satellite count.
- ✏ Edit button
- Opens inline edit form. You can change the name, minimum elevation angle, and altitude above sea level. The cone updates live as you type the elevation angle.
- 👁 Eye button
- Toggles the station's cone and marker invisible without removing it from the list. The station stays in the list and can be re-shown at any time.
- VISIBLE / HIDDEN
- Global toggle at the top of the Ground Stations section — hides or shows all station cones at once.
- ✕ Remove
- Permanently removes the station from the list.
Satellite Colouring
When a satellite enters a ground station's visibility cone (elevation ≥ the station's minimum), it changes colour to match that station. The side panel satellite list dots also update. This works across all active (non-hidden) stations simultaneously — first matching station wins if a satellite is in multiple cones at once.
Remembering Your Stations
All station configurations — including custom stations, edited values, and hidden states — are automatically saved to your browser's local storage. They are restored the next time you open the page, with no action required.
TIP — Try setting Svalbard's minimum elevation to 0° — it has near-polar coverage and will briefly see almost every LEO satellite as they pass overhead. Its cone becomes a wide flat disk covering most of the visible sky.
The Timeline Scrubber
The bar at the bottom of the globe controls simulated time. By default the tracker runs in LIVE mode showing real current positions. You can travel up to ±24 hours from the present.
Controls
- LIVE button
- Returns immediately to real time and cancels any playback.
- ◀◀ Slower
- Steps through speed presets: −3600×, −600×, −60×, −10×, −1×, pause, 1×, 10×…
- ▶▶ Faster
- Steps up through the same preset speeds in the forward direction.
- Scrubber drag
- Drag the glowing dot left (past) or right (future). Everything updates instantly.
What Responds to the Timeline
When you change the time — by scrubbing, playing forward or backward, or pressing LIVE — every time-dependent element updates simultaneously:
- Satellite positions
- All satellites move to where they actually were/will be at that time
- Earth rotation
- Globe rotates to the correct GMST (Greenwich Mean Sidereal Time)
- Day/night terminator
- Sun direction computed from real solar position at that time
- Ground station cones
- Rotate with Earth to the correct position
- Satellite colours
- Reflect which satellites are in view of ground stations at that time
- Orbit path ring
- Shows future orbit from the selected time, not from now
TIP — Set speed to 60× and watch the ISS orbit the globe every ~92 minutes in about 90 seconds of real time. At 3600× you can watch a full day of satellite traffic in 24 seconds.
The HUD clock in the top-right header always shows the current real UTC time — it never freezes or scrubs with the simulation, giving you a stable reference point. When not in LIVE mode, the globe crosshair label changes from "LIVE ORBITAL VIEW" to "SIMULATED TIME" in orange as a clear reminder that the globe is showing a different moment than the wall clock.
Local Filter
Typing in the search box immediately filters the satellite list to matching names or types. This is instant — no network call. The regime filter (LEO/MEO/GEO) and search filter work together.
Remote Search via CelesTrak
If your search term doesn't match any satellite in the current list, GROUNDTRACK automatically queries the CelesTrak NAME= endpoint after 600ms of typing. This searches their full catalog of thousands of tracked objects.
- + LIST button
- Adds the satellite to the globe as a tracked object. It appears immediately on the globe and in the side list. The result stays on screen so you can add multiple.
- VIEW button
- Adds the satellite (if not already added) and immediately selects it, centres the camera, draws the orbit ring, and returns to the normal list.
- ← BACK TO LIST
- Clears the search results and returns to the normal satellite list without adding anything.
- IN LIST badge
- Shown if a CelesTrak result is already tracked — clicking it selects the existing satellite.
Satellite Cap
The tracker supports up to 500 satellites simultaneously. Above this, performance degrades noticeably on most hardware. The cap is enforced when adding via search — you'll see a message if you reach it. The default loaded set is well within this limit.
TIP — Search "STARLINK" to see all available Starlink satellites from the live CelesTrak feed and add several at once. The LEO filter then shows just the Starlink constellation orbiting in their characteristic shell pattern.
Press Escape
Pressing Escape clears the search box and returns to the full satellite list. Also cancels ground station placement mode and closes this manual.
