Satellite Orbits
From geostationary orbit 35,786 km above Earth to low Earth orbit constellations, satellites occupy different orbital regimes for different purposes. Understanding orbit types is essential to understanding satellite communications.
Orbital Regimes
Satellites orbit at different altitudes depending on their purpose. Each orbit has distinct characteristics for latency, coverage, and launch requirements.
Geostationary Orbit (GEO) - 35,786 km
Satellites in GEO orbit at the same speed Earth rotates, appearing stationary in the sky. A single satellite can cover about 1/3 of Earth's surface. GEO is ideal for communications and weather satellites but has high latency (~600 ms round trip) and requires powerful发射机.
Medium Earth Orbit (MEO) - 2,000-35,786 km
MEO is home to navigation constellations like GPS (20,200 km), GLONASS, Galileo, and BeiDou. At this altitude, satellites have lower latency than GEO while requiring fewer satellites than LEO for global coverage.
Low Earth Orbit (LEO) - 200-2,000 km
LEO satellites offer the lowest latency (20-40 ms) but cover small areas, requiring constellations for global service. Starlink operates at 550 km, OneWeb at 1,200 km. The short orbital lifetime means LEO satellites eventually burn up in Earth's atmosphere.
LEO Constellation Economics
OneWeb needs 648 satellites, Starlink plans 42,000+ for global coverage. At $500,000 per satellite and $50 million per launch, building a LEO constellation requires billions in capital. Yet companies keep trying because the addressable market—global broadband—represents trillions in potential revenue.