How do geostationary satellites maintain their position?

Geostationary satellites maintain their position by orbiting the Earth at the same rotational speed as the Earth.

Geostationary satellites are positioned in a specific orbit called the geostationary orbit, which is approximately 35,786 kilometres above the Earth's equator. At this altitude, the satellite's orbital period matches the Earth's rotational period, which is 24 hours. This means the satellite orbits the Earth once every 24 hours, synchronising with the Earth's rotation. As a result, the satellite appears to be stationary relative to a fixed point on the Earth's surface.

To achieve this, the satellite must be placed in an orbit where its angular velocity matches the Earth's rotational velocity. This is only possible at the geostationary altitude. If the satellite were closer to the Earth, it would orbit faster than the Earth's rotation, and if it were farther away, it would orbit more slowly. The precise balance at the geostationary altitude ensures that the satellite remains in a fixed position relative to the Earth's surface.

Additionally, geostationary satellites are typically equipped with thrusters that make small adjustments to their position and velocity. These adjustments, known as station-keeping manoeuvres, counteract the effects of gravitational perturbations from the Moon, the Sun, and the Earth's equatorial bulge, which can cause the satellite to drift from its designated position. By making these periodic corrections, the satellite can maintain its geostationary position over the long term.

This stable positioning is crucial for applications such as weather monitoring, telecommunications, and broadcasting, where a constant view of the same area on the Earth's surface is necessary.