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Home > Geostationary transfer orbit


A geostationary transfer orbit (GTO) is a Hohmann transfer orbit around the Earth between a low Earth orbit (LEO) and a geostationary orbit (GSO). It is an ellipse where the perigee is a point on the LEO and the apogee has the same distance from the Earth as the GSO.

More generally, a geosynchronous transfer orbit is an intermediate orbit between a LEO and a geosynchronous orbit.

After a typical launch the inclination of the LEO (the angle between the plane of the orbit and the plane of the equator) is determined by the latitude of the launch site and the direction of launch. The GTO inherits the same inclination. The inclination must be reduced to zero to obtain a geostationary orbit. This is done at the GSO distance because that requires less energy than at LEO.

A launch vehicle can move from LEO to GTO by firing a rocket at a tangent to the LEO to increase its velocity. Typically the upper stage of the vehicle has this function. Once in the GTO, it is usually the satellite itself that performs the conversion to geostationary orbit by firing a rocket at a tangent to the GTO at the apogee.

The spent upper stages of launch vehicles are left behind in the GTO.

Astrodynamics Earth orbits

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