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LEO, MEO & GEO Satellite Systems: A Comparison

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In the immense expanse of outer space, satellites orbiting our planet are carrying out a multitude of tasks, from weather forecasting and global positioning to communication and broadcasting. These satellites, depending on their purpose and the region of space they occupy, can be broadly classified into Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and Geostationary or Geosynchronous Orbit (GEO). Each of these satellite systems has its unique set of characteristics and uses. In this blog, we will delve into the fascinating world of satellite technology, drawing a comparison between LEO, MEO, and GEO systems to help you understand their distinct functionalities and the critical role they play in our daily lives. Sit back, buckle up, and let’s embark on this cosmic journey!

Satellite technology, a marvelous feat of human ingenuity, has revolutionized the way we live, work, and communicate. Essentially, satellites are artificial objects intentionally placed into orbit to serve various purposes like communications, weather monitoring, navigation, and earth observation. They operate by receiving signals from an earth station and then retransmitting these signals back to other earth stations. They are powered by solar energy and continue to function as long as they remain undamaged and have a power supply. It’s important to note that the operational efficiency of a satellite greatly depends on its altitude and the orbit it resides in – LEO, MEO, or GEO. Each of these orbits, offering different conditions, makes the respective satellite system suitable for specific applications. As we go deeper into this topic, we’ll learn more about these distinct orbits and their respective satellite systems.

We often overlook the immense value satellites offer in our everyday lives. They have become an integral and indispensable part of modern society. Satellites are involved in many aspects, from the GPS we use to navigate our drives, and the weather forecast we check each morning, to the communication tools we use to connect with people across the globe. Moreover, they provide critical insights for scientific research, like studying climate change patterns or observing distant astronomical objects. But it’s not just about the far-reaching or global-scale applications; satellites also aid in emergency rescue missions, making a life-saving difference. Overall, satellites play a pivotal role in making our lives more convenient and safer, enhancing our understanding of the world and beyond.

Comparison of LEO, MEO & GEO

Satellite Systems can be classified based upon their orbits as low earth orbit, medium earth orbit & geostationary earth orbit systems. Geostationary is also the highest earth orbit and hence, also provides the greatest visibility using only a few satellites. The coverage region of a satellite is called its footprint. This is the region from which the satellite is visible. Three geostationary satellite footprints ensure complete coverage of the earth as shown:

Hence, there is permanent or 24-hour visibility of geostationary satellites without the need for handoffs. While LEO & MEO satellites do not have 24-hour visibility as the satellites have smaller footprints since they are closer to the earth (low satellite height). Hence, a larger number of satellites are needed to cover the earth. Also, since each satellite has a small footprint, handoffs are also required between satellites.

Major differences between LEO, MEO & GEO satellite systems:

ParameterLEOMEOGEO
Satellite Height500-1500 km5000-12000 km35,800 km
Orbital Period10-40 minutes2-8 hours24 hours
Number of Satellites40-808-203
Satellite LifeShortLongLong
Number of HandoffsHighLowLeast(none)
Gateway CostVery ExpensiveExpensiveCheap
Propagation LossLeastHighHighest

Note –

  • HEO refers to highly elliptical orbits which have a visibility of about 12 hours.
  • ICO or intermediate circular orbit is an example of MEO.
  • GPS satellites are not in Geostationary orbits but instead, they orbit twice for every rotation of the earth at a height of 20, 000 km.
  • Handheld terminals have low sending power are hence use LEO for mobile communication. LEOs are also closest to the earth, have better signal strength, and less time delay.

Low Earth Orbit (LEO) Satellites

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Characteristics of LEO Satellites

LEO satellites offer a handful of notable characteristics, primarily due to their close proximity to Earth. Firstly, they have a high orbital speed, completing a rotation around the Earth in about 90 to 120 minutes, meaning that a network of LEO satellites is needed to provide continuous coverage. Secondly, due to their lower altitude, LEO satellites have a smaller coverage area, but they deliver better resolution and higher quality data transmission due to less free-space loss. This results in lower latency, which is the reason LEO satellites are preferred for real-time communications. Lastly, it’s worth noting that LEO satellites require less power to transmit data, but their lifespan tends to be shorter than their higher altitude counterparts, requiring more frequent replacements.

Applications and Uses of Low Earth Orbit (LEO) Satellites

LEO satellites play a pivotal role in numerous modern technological applications. They are commonly used in telecommunication services – their low latency makes them ideal for voice and video communication, even over long distances. Companies like Starlink and OneWeb are currently building large constellations of LEO satellites to provide global broadband internet coverage.

Another significant use of LEO satellites is in remote sensing and environmental monitoring. Their proximity to Earth enables them to capture high-resolution data, making them very useful for earth observation tasks such as monitoring climate change, tracking hurricanes, or mapping the Earth’s surface.

LEO satellites also play a critical role in scientific research. International Space Station (ISS), for example, is situated in a LEO. It facilitates research in biology, human biology, physics, astronomy, and meteorology.

Further, they’re used in Global Positioning System (GPS) services. While GPS primarily uses MEO satellites, some LEO satellites are implemented to improve coverage and precision.

Lastly, they are used in military and spy activities. The high-resolution and low-latency data offered by LEO satellites are invaluable for surveillance, reconnaissance, and communication purposes in military operations.

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Medium Earth Orbit (MEO) Satellites

Photo by NASA on Unsplash

Characteristics of MEO Satellites

MEO satellites, orbiting the Earth at an altitude ranging from 2,000 to 36,000 kilometers, occupy the space between LEO and GEO satellites. This unique position enables MEO satellites to balance the benefits of both high and low-orbiting satellites.

The latency of MEO satellites is higher than LEO satellites but considerably less than GEO satellites, making them suitable for applications that require moderate latency. Their relatively high altitude gives them a larger coverage area than LEO satellites, yet they still maintain a stronger signal strength than GEO satellites.

MEO satellites’ orbital period is longer than LEO satellites, typically ranging from 2 to 24 hours. This means individual satellites can stay within range of a specific ground station for a longer period, reducing the need for a large number of satellites in a network.

Despite these advantages, MEO satellites are more challenging to launch and maintain than LEO satellites due to their higher altitude. However, the long-term benefits they offer in terms of coverage and latency make them a popular choice for various applications.

Applications and Uses of Medium Earth Orbit (MEO) Satellites

MEO satellites are extensively employed in navigation systems like GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), and Galileo. Because of their moderate altitude and latency, they can provide accurate location information with better precision and quicker response times than their GEO counterparts.

They are also used for telecommunication services, including mobile voice and data communication. Their larger coverage area and stronger signal strength make them ideal for providing consistent and reliable communication services, especially in remote and underserved regions.

Scientific research and weather monitoring are other areas where MEO satellites have considerable utility. These satellites can capture detailed atmospheric data, aiding meteorological predictions and contributing to the study of climate change. Their relatively long orbital period allows for extended observation times, which can be critical in tracking and understanding long-term weather patterns and phenomena.

Despite the challenges associated with their launch and maintenance, the versatile applications of MEO satellites underscore their vital role in our interconnected world.

Geostationary or Geosynchronous Orbit (GEO) Satellites

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Characteristics of GEO Satellites

Geostationary satellites, or GEO satellites, are positioned at an altitude of approximately 36,000 kilometers above the Earth’s equator and rotate with the Earth’s rotational speed, which gives them a stationary position relative to the Earth’s surface. This constant positioning enables uninterrupted, high-quality reception of signals. However, GEO satellites have a wider latency compared to LEO and MEO satellites due to their high altitude.

They possess the capability of coverage over a large geographical area- one GEO satellite can cover up to one-third of the Earth’s surface. But, this also results in a lower spatial resolution. GEO satellites also have the longest lifespan among the three, with operational lives often reaching 15 years or more. However, due to their high altitude, launching and positioning GEO satellites is complex and energy-intensive.

Their unique characteristics make them an excellent choice for a wide range of services, including broadcasting, weather forecasting, and telecommunications. Despite their limitations, the broad, constant coverage and prolonged lifespan of GEO satellites make them an invaluable tool in our global communication systems.

Applications and Uses of Geosynchronous Orbit (GEO) Satellites

GEO satellites find extensive use in many areas. For instance, they are integral to television broadcasting, where their large coverage area allows broadcasting to entire continents simultaneously. This is why most television broadcast satellites are in GEO. They also play a significant role in telecommunications, enabling long-distance phone calls and internet connectivity in remote, rural areas.

Meteorological departments worldwide rely on GEO satellites for weather prediction and climate monitoring. These satellites provide a stable platform for observing atmospheric and weather conditions in consistent geographical locations. This constant monitoring aids in the early detection of natural calamities, ensuring timely evacuations and preparations.

Moreover, GEO satellites are employed in intelligence and military operations. Their stationary positioning allows for persistent surveillance of a specific region, contributing to national security.

In research and development, GEO satellites help in studying space weather and the geosynchronous environment, which is crucial for the advancement of space science. Despite the challenges in launching and maintaining GEO satellites, their wide-ranging applications and constant coverage make them an essential part of our global infrastructure.

The Future of Satellite Technology

Photo by NASA on Unsplash

The future of satellite technology paints an exciting picture. With advancements in technology, we could see NanoSatellites and CubeSats, much smaller and lighter than traditional satellites, becoming more prevalent. These can be launched in large numbers, creating what is known as a satellite constellation, to provide global coverage. Besides, the advent of high-throughput satellites (HTS) is likely to revolutionize the satellite communication landscape, boasting higher data transmission rates and bandwidth.

In the realm of LEO, MEO, and GEO, there’s much to look forward to as well. LEO satellites are set to play a pivotal role in providing global broadband connectivity, with mega-constellations planned by companies like SpaceX. MEO satellites might see an increased role in navigation and timing services, considering their advantageous middle-ground position. As for GEO satellites, enhancements in technology could optimize their use in weather prediction, climate studies, and space exploration.

However, with greater proliferation of satellites, the industry needs to address challenges like space debris management and sustainable satellite design. With the right balance of innovation, regulation, and responsibility, the future of satellite technology holds tremendous promise.

Conclusion

To sum up, LEO, MEO, and GEO are distinct types of orbits used for satellites, each with unique characteristics and applications. LEO satellites operate closest to the Earth, providing low-latency communication and images with high resolution, making them ideal for spy missions, weather monitoring, and Internet service provision in remote areas. MEO satellites, positioned in the middle-distance orbit, are primarily used for navigation systems like GPS, GLONASS, and Galileo. Lastly, GEO satellites revolve at the same rotational speed as the Earth, offering continuous coverage over specific regions. They are widely used in telecommunications, television broadcasting, weather forecasting, military surveillance, and space science research. Despite the challenges associated with launching and maintaining satellites, the vast array of applications they serve makes them invaluable assets in our global infrastructure.

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2 Comments

  1. Good information but I need to know few more things, why orbits are measured in sidereal time ,why not in solar time and why HEO have lowest point distance if approx 100 n.mi?

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