BlogNCERTImportant Topic of Physics: Geostationary Satellites

Important Topic of Physics: Geostationary Satellites


A geostationary satellite is in an orbit that can only be attained at a height of 35,786 km (22,236 miles) and keeps it fixed over one longitude at the equator. To ground observers, the satellite seems stationary in a fixed place in the sky. In this orbit, there are hundreds of communication satellites and numerous meteorological satellites.

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    The word “geostationary” refers to a satellite that appears practically stationary in the sky when viewed from the ground. A single geostationary satellite has a direct line of sight with roughly 40% of the earth’s surface. With the exception of small circular zones located at the north and south geographic poles, three such satellites separated by 120 degrees longitude can offer coverage of the whole planet. A directional antenna, generally a tiny dish, directed at the spot in the sky where the satellite appears to hover, can be used to access a geostationary satellite.

    The main benefit of this sort of satellite is that an earthbound directional antenna may be targeted and then left in place without needing to be adjusted again.

    Another benefit is that because highly directional antennas can be utilized, interference from ground-based sources as well as other satellites is reduced.

    Limitations of Geostationary satellites:

    There are two primary drawbacks of geostationary satellites. For starters, because the orbital zone is a very narrow ring in the plane of the equator, the number of satellites that can be kept in geostationary orbits without colliding is limited. Second, an electromagnetic (EM) signal must travel a minimum of 71,600 kilometers (44,600 miles) to and from a geostationary satellite.

    When an EM signal travels at 300,000 kilometers per second (186,000 miles per second) from the surface to the satellite and back, a lag of at least 240 milliseconds is added.

    Geostationary satellites also have two other, less critical issues. First, due to gravitational interaction between the satellite, the earth, the sun, the moon, and the non-terrestrial planets, the exact position of a geostationary satellite relative to the surface varies slightly throughout the course of each 24-hour period. The satellite travels around the sky in a rectangular zone known as the box, as seen from the ground. Although the box is small, it restricts the sharpness of the directed pattern and thus the power gain that earth-based antennas may achieve.

    Second, because the sun is a major source of EM radiation, there is a dramatic increase in background EM noise when the satellite approaches the sun as seen from a receiving station on the ground. Solar fade is a concern only a few days before and after the equinoxes in late March and late September. Even so, episodes are only a few minutes long and only happen once a day.

    Low Orbit Satellites:

    Low-earth-orbit (LEO) satellite systems have become increasingly common in recent years. This system uses a fleet or swarm of satellites, each in a polar orbit at a few hundred kilometers in height. Each revolution lasts anything from 90 minutes to several hours.

    A satellite like this comes into range of every location on the earth’s surface for a specific amount of time during the course of a day. An LEO swarm’s satellites are carefully positioned so that at least one satellite is always visible from any point on the surface. In a worldwide cellular network, the satellites serve as moving repeaters.

    An LEO satellite system allows for the use of simple, non-directional antennas, lower latency, and avoids solar fading. These are cited as LEO systems’ advantages over geostationary satellites.

    Application of Satellites:

    Forecasting the weather:

    We can’t anticipate the weather without the help of satellites. Satellites have made the greatest contribution to making weather change predictions by examining various worldwide situations.

    Several satellites use infrared or visible light to take photographs of the earth.

    Weather forecasting is accomplished by equipping satellites with unique instruments and sophisticated cameras that monitor numerous climate elements such as air pressure, temperature, and humidity, among others. Weather satellites are spacecraft that are used to forecast the weather.

    Satellites used by the military:

    The use of satellites for espionage is one of the oldest applications of satellites. The majority of communication links are maintained via satellite since they are far less vulnerable to enemy attacks.

    Navigational satellites:

    Despite the fact that it was initially primarily utilized for military purposes, the GPS (Global Positioning System) is today well-known and accessible to the general public.

    All of our navigation systems, Google maps, and other similar services allow for perfect global localization, and with some extra techniques, the precision can reach a few meters.

    GPS is used by almost all planes and ships as a supplement to traditional navigation systems. Many automobiles and vehicles come equipped with GPS receivers. This system is also utilized for truck fleet management and vehicle tracking in the event of theft.

    Mobile communication on a global scale:

    Satellites are now being used to facilitate worldwide mobile data connectivity. Geostationary satellites are not suited for this activity due to their significant latency; thus, satellites in lower orbits are required. Satellites for mobile communication are primarily used to increase the coverage area of current mobile phone networks, rather than to replace them. Cellular phone systems like AMPS and GSM, as well as their successors, do not cover the entire country.

    Also read: The Angle Of Contact

    Frequently Asked Questions FAQs:

    Question 1: What are the different types of Satellites?

    Answer: Since satellites are deployed into space to perform a specific task, they can be categorized according to their function. The satellite must be built precisely to perform its function. Communications satellites, remote sensing satellites, navigation satellites, LEO, MEO, HEO, GPS, GEOs, drone satellites, ground satellites, and polar satellites are among the nine types of satellites.

    Question 2: Define Geostationary satellite?

    Answer: A geostationary satellite is in an orbit that can only be attained at a height of 35,786 km (22,236 miles) and keeps it fixed over one longitude at the equator. To ground observers, the satellite seems stationary in a fixed place in the sky.

    Question 3: What is GPS?

    Answer: The Global Positioning System, or GPS, is a satellite navigation system that offers location, velocity, and time synchronization. GPS may be found almost anywhere. GPS systems can be found in your automobile, smartphone, and watch.

    Question 4: What are the elements of GPS?

    Answer: The GPS system is made up of three parts, known as segments, that operate together to produce location data. Space, ground control, and user equipment.Satellites circling the Earth deliver signals to users based on their geographical location and time of day. The Control Segment consists of Earth-based monitor stations, master control stations, and a ground antenna. Tracking and operating satellites in space, as well as monitoring signals, are all part of the control tasks. Monitoring stations can be found on nearly every continent, including North and South America, Africa, Europe, Asia, and Australia.GPS receivers and transmitters, such as watches, smartphones, and telematic devices, are examples of user equipment.

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