Geostationary Transfer Orbit
A highly elliptical Earth orbit used to transfer a spacecraft from a low Earth parking orbit to geostationary orbit.
Explanation
GTO is a standard intermediate orbit in the journey from LEO to GEO. A launch vehicle typically injects its payload into a GTO with a low perigee (a few hundred kilometers) and an apogee near GEO altitude (35,786 km). The spacecraft then uses its own propulsion to circularize at apogee. The exact GTO parameters vary by launch site and vehicle. Launches from Cape Canaveral produce GTOs inclined at about 27 degrees (matching the launch site latitude), while launches from Kourou produce GTOs at about 5 degrees. The lower inclination from Kourou saves substantial propellant — roughly 15-20% more payload to GEO compared to Cape Canaveral, which is why many commercial GEO operators launch from French Guiana. Supersynchronous transfer orbits — where apogee exceeds GEO altitude — are sometimes used to reduce the inclination change penalty, though they extend the transfer time.
Why It Matters
GTO performance defines the economics of GEO satellite delivery. Launch vehicle payload specifications are often quoted in both GTO and LEO figures, and the difference tells you how efficiently a rocket can reach the high-value GEO market.
Concept Map
How Geostationary Transfer Orbit connects to other glossary terms:
Frequently Asked Questions
How long does it take to go from GTO to GEO?
Typically 5-7 days for chemical propulsion, or several months for electric propulsion.
Why do some launch providers quote GTO mass instead of GEO?
Because the spacecraft's own propulsion system determines the final delta-v to reach GEO, so GTO mass is a more standardized measure of launch vehicle performance.
Sources
Last updated: July 1, 2026