Geosynchronous vs Geostationary Satellite Orbits: Key Differences

Geosynchronous Orbit (GSO) and Geostationary Orbit (GEO) are critical types of orbits used for positioning satellites to maintain specific positions relative to Earth.

A geosynchronous orbit ensures that a satellite has an orbital period matching Earth’s rotation, causing it to return to the same spot in the sky each day. A geostationary orbit, a special case of GSO, keeps a satellite fixed over the equator at an altitude of approximately 35,786 kilometers. This stationary positioning relative to Earth’s surface makes GEO ideal for communications, weather monitoring, and navigation satellites, providing continuous coverage and reliable data transmission.

Both types of orbits play essential roles in modern satellite operations, offering unique advantages for various applications.

What is Geosynchronous Orbit?

Following are the features of Geosynchronous Orbit:

• The orbit around the Earth with an orbital period equal to one sidereal day (i.e., 23 hours, 56 minutes, 4 seconds) is known as Geosynchronous orbit. The word “synchronous” means the object in this orbit returns to the same position after a period of 1 sidereal day to the observer on the Earth’s surface.
• There are many such orbits around the Earth.
• It may be circular or non-circular.
• Geosynchronous satellite has inclination with respect to the equator.

Figure 1 depicts Geosynchronous and Geostationary orbit types.

Applications or Examples of Geosynchronous Satellites

• Spy Satellites: Some reconnaissance satellites use geosynchronous orbits to observe specific regions of the Earth, allowing them to revisit the same area at the same time each day.
• Scientific Satellites: Such as those used for Earth observation or space science missions, where consistent, periodic observation of a particular region or object is required.

What is Geostationary Orbit?

Following are the features of Geostationary Orbit:

• The circular orbit at the altitude of 35768 Kms above the equator of the Earth, which follows the direction of rotation of the Earth, is known as Geostationary orbit.
• An object in this orbit has a period equal to the rotation period of the earth. Hence, it appears motionless from earth or at a fixed position to observers on the ground with respect to his/her position. This is similar to how a star looks to observers on the earth. Hence the word “stationary”.
• There is only one such orbit around the Earth.
• It is one type of Geosynchronous orbit.
• It is a circular orbit.
• Geostationary satellite has zero inclination with respect to the equator.

Applications or Examples of Geostationary Satellites

• Communications Satellites: Such as those used by companies like Intelsat, Inmarsat, and SES. These satellites provide consistent coverage over a specific geographic area, facilitating reliable communications services like TV broadcasting, internet, and telephony.
• Weather Satellites: Like the GOES (Geostationary Operational Environmental Satellite) series, which monitor weather patterns and provide real-time data for forecasting.
• Navigation Satellites: Some global positioning systems (GPS) satellites, such as those in the Indian Regional Navigation Satellite System (IRNSS), operate in geostationary orbits.

Difference between Geosynchronous and Geostationary orbit

Conclusion

Geosynchronous and geostationary orbits are crucial for various satellite applications due to their ability to provide continuous and predictable coverage over specific areas of the Earth. While all geostationary satellites are geosynchronous, not all geosynchronous satellites are geostationary, with the main difference being their orbital inclination and resulting position relative to the Earth’s surface.