What is GEO?
Geostationary orbit (GEO) is a circular equatorial orbit at exactly 35,786 km altitude. At this altitude, a satellite's orbital period equals Earth's rotation period (23h 56m 4s), making it appear stationary above a fixed point on the equator. A single GEO satellite covers approximately 43% of Earth's surface, and three evenly spaced satellites provide near-global coverage up to 70° latitude.
Latency: the fundamental constraint
The radio signal travels 35,786 km to the satellite and another 35,786 km back to the ground station, adding approximately 240 ms of propagation delay each way. Total round-trip time (RTT) is typically 550–600 ms — an inherent physical limitation that makes GEO unsuitable for latency-sensitive applications such as VoIP, gaming, or video conferencing without mitigation techniques.
Advantages and key uses
GEO's fixed apparent position eliminates the need for tracking antennas on the ground, dramatically reducing terminal cost. This makes GEO ideal for broadcast (direct-to-home TV, VSAT networks), weather observation (Meteosat, GOES), and government/military communications where cost-per-bit matters more than latency. Major GEO operators include Intelsat, SES, Eutelsat, Viasat, and Inmarsat.
Polar coverage gap
GEO satellites cannot serve areas above approximately 75–81° latitude because the elevation angle becomes too low or the satellite drops below the horizon. Arctic and Antarctic operations require supplemental HEO or LEO satellites.