Orbital Regimes
| Orbit | Altitude | Period | Key Uses | Examples |
|---|---|---|---|---|
| LEO | 200–2,000 km | ~90–127 min | Broadband, imaging, ISS | Starlink, ISS, Planet |
| MEO | 2,000–35,786 km | ~2–24 hrs | Navigation | GPS, Galileo, GLONASS |
| GEO | 35,786 km | ~24 hrs (synchronous) | TV, weather, comms | GOES, Intelsat, SES |
| SSO | 600–800 km (typical) | ~97–100 min | Earth observation | Landsat, Sentinel |
| HEO | Varies (high apogee) | ~12 hrs (Molniya) | Comms at high latitudes | Molniya, Tundra |
| GTO | ~250 × 35,786 km | ~10.5 hrs | Transfer to GEO | Rocket upper stages |
Low Earth Orbit (LEO)
LEO is the most populated orbital regime, home to the ISS (~420 km), Tiangong (~390 km), Starlink (~480–550 km), and thousands of Earth observation and scientific satellites. Its proximity to Earth enables low-latency communications and high-resolution imaging. The trade-off is atmospheric drag, which limits satellite lifetimes and requires periodic orbit maintenance.
Geostationary Orbit (GEO)
At exactly 35,786 km altitude above the equator, a satellite's orbital period matches Earth's rotation, making it appear stationary from the ground. This is ideal for continuous coverage of a fixed region — used extensively for weather monitoring, television broadcasting, and telecommunications. GEO slots are a finite, regulated resource.
Sun-Synchronous Orbit (SSO)
A polar or near-polar orbit carefully tuned so the satellite passes over any given point at the same local solar time on each orbit. This ensures consistent lighting conditions — essential for Earth observation and remote sensing missions.
Other Notable Orbits
Highly Elliptical Orbits (HEO) such as the Molniya orbit provide extended coverage of high-latitude regions. Graveyard orbits are used to move defunct GEO satellites out of the operational belt. Lagrange points (not orbits around Earth, but gravitationally stable points in the Sun-Earth system) are used by JWST and other deep-space observatories.