Understanding Properties Of Geostationary Orbits

A geostationary orbit is a circular orbit 35,785 km (22,236 miles) above the equator in which a satellite’s orbital period equals the earth’s rotation period of 23 hours and 56 minutes. A spacecraft in this orbit seems to be motionless in the sky to an observer on earth. This orbit is mainly utilised by meteorological and communications satellites. The geostationary orbit is a subset of the geosynchronous orbit, which is defined as any orbit having a period equal to the period of the earth’s rotation. In 1945, British novelist and physicist Arthur C. Clarke introduced the concept for such an orbit in a Wireless World article titled “Extra-Terrestrial Relays.” The paper anticipated today’s communications satellite system, which sends radio and television signals throughout the world.

Describes Geostationary Orbit

A satellite in geostationary orbit remains precisely above the equator. Therefore, its position about a point on earth does not change. A geostationary orbit is a path assigned to high-earth orbiting satellites for weather monitoring, observation, and communication. High earth orbits are orbits that are approximately 22,236 miles (35,786 kilometres) above the equator of the earth. This is an appropriate position since the earth’s gravitational pull keeps the satellite’s speed equal to the earth’s orbit velocity.

Geostationary Satellite Concept

In the 1940s, fiction writer Arthur C. Clarke promoted the concept of geostationary orbits as a popular means to modernise telecommunication. The first satellite was launched into geostationary orbit in 1963.

Communication satellites are the most regularly put spacecraft in these geostationary orbits. This allows earth satellite antennas to point continuously towards the position in the sky where the satellites are stationed, rather than rotating to monitor them.

Features of Geostationary Satellite 

The numerous satellites used for different types of communications, including television, are best known for their geostationary orbits of 36,000km from the earth’s equator. These satellites’ signals can be beamed across the earth. Telecommunications need their satellite to be “seen” at all times; therefore, it must remain fixed in the same locations relative to the earth’s surface. 

A fixed satellite has the benefit of remote sensing in that it always sees the earth from the same perspective, allowing it to record the same image at regular intervals. This configuration is very good for observing weather conditions. One downside of geostationary orbits is the large distance between them and the earth, which limits the available spatial resolution. To give a worldwide picture, several weather satellites are evenly dispersed in geostationary orbit around the planet.

The Properties of a Geosynchronous Orbit

The following are the properties of a geosynchronous orbit:

Inclination

The geostationary earth orbit’s inclination is zero, guaranteeing that the orbit’s inclination remains above the equator at all times, keeping it stationary for ground observers.

Period

The geostationary orbit has an orbital period of twenty-four hours or one earth day. This means that the satellite will return to its original location after twenty-four hours regardless of its other features.

Eccentricity

The eccentricity of the geostationary orbit is zero due to its complete round, which benefits the fact that the satellites are at a constant radius from the earth, which aids in its tracking.

With the exception of tiny circular zones located at the north and south geographic poles, three such satellites spread by 120 degrees of longitude can provide global coverage. A geostationary satellite may be found by directing a directional antenna, often a tiny dish, at a spot in the sky where the spacecraft seems to hover.

The fundamental advantage of this type of satellite is that an earthbound directional antenna may be targeted and then left in place without further modification. Another advantage is that because very directional antennas may be used, interference from ground-based sources and other satellites is decreased. Geostationary satellites are constrained in two ways.

The number of satellites that can be maintained in geostationary orbits without mutual conflict (or even collision) is restricted, for example, since the orbital zone is a relatively tight ring on the equatorial plane. Second, a geostationary satellite’s electromagnetic (EM) signal must travel at least 71,600 kilometres (44,600 miles) to and from it. When an EM signal travels at 300,000 kilometres per second (186,000 miles per second) from the surface to the satellite and back, it introduces a delay of at least 240 milliseconds.

Conclusion

A geostationary satellite is an earth-orbiting spacecraft that circulates in the same direction as the earth, at an altitude of roughly 35,800 kilometres (22,300 miles) directly above the equator (west to east). At this height, one orbit takes 24 hours, the same amount of time it takes the earth to circle once on its axis. The word “geostationary” refers to a satellite that looks practically stationary in the sky to a ground-based observer. A single geostationary satellite has a direct line of sight over around 40% of the earth’s surface.