CBSE Class 11 Earth satellites Detail and Preparation Downloads
The satellites are launched with a specific objective in mind pertaining to several uses such as communications, research in scientific areas, forecasting the weather, and intelligence. Once out in space, all the different types of satellites follow similar physics principles and are governed by the same maths equations.
Apart from these, the earth has many man-made satellites that are placed in the orbit and are used for different applications in communications and information gathering. As the term itself states, an artificial satellite is one that is put in our space by human efforts and follows the orbit of natural satellites.
What is a Satellite?
An object orbiting around the sun, earth or any other colossal body is known as a satellite. There are two major types of categorization when it comes down to satellites, one is natural and the other is man-made.
Some examples of natural satellites are planets, moons, and comets. Jupiter has 67 natural satellites. The earth has one permanent natural satellite, the moon we know, which causes the tides in the sea. Sometimes other objects (like asteroids) can enter into temporary orbits of the earth and become a natural satellite for a span.
Since they have a very large view field, they can collect data a lot faster than instruments that can be used at ground level. Apart from this, their view into space beyond earth is not blocked by clouds, dust, and other obscurities, due to which a satellite can view space a lot more efficiently than telescopes on earth.
Currently, there are more than 2,500 man-made satellites orbiting the earth. Most of these are of Russian origin. You may wonder why none of these satellites collide with each other, considering the volume. Actually, it is quite possible for this to occur. Although care is taken to launch a satellite in specific orbits such that collisions never occur, these orbits can vary in nature. There are many international organisations in place to prevent such occurrences. However, in 2009, a couple of Russian and American satellites did collide for the first time!
The satellites are launched with a specific objective in mind pertaining to several uses such as communications, research in scientific areas, forecasting the weather, and intelligence. Once out in space, all the different types of satellites follow similar physics principles and are governed by the same maths equations.
Based on their purpose, there are two kinds of artificial satellites. They are geostationary satellites and polar satellites.
Types of Satellites:
There are several types of satellites, each designed for specific purposes and functions. The classification of satellites is based on their primary mission objectives and the orbits in which they operate. Here are the main types of satellites with explanations:
Communication Satellites:
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Purpose: Relay signals for television, radio, internet, and telephone communication.
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Orbit: Communication satellites are often placed in geostationary orbits (GEO) at an altitude of approximately 35,786 kilometres. This orbit allows them to remain fixed relative to a specific point on the Earth's surface.
Earth Observation Satellites:
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Purpose: Monitor and collect data about the Earth's surface, atmosphere, and oceans for scientific, environmental, and military purposes.
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Orbit: Earth observation satellites can operate in various orbits, including low Earth orbit (LEO), medium Earth orbit (MEO), and polar orbits. The choice of orbit depends on the mission's objectives.
Navigation Satellites:
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Purpose: Provide global positioning system (GPS) services for navigation, location-based applications, and precise timing.
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Orbit: Navigation satellites are typically placed in medium Earth orbit (MEO) to ensure global coverage. The GPS constellation, for example, consists of satellites in MEO.
Weather Satellites:
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Purpose: Monitor and track weather patterns, collect atmospheric data, and aid in weather forecasting and disaster management.
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Orbit: Weather satellites can be in geostationary orbit (GEO) to provide continuous monitoring of a specific region or in polar orbits for global coverage.
Scientific Satellites:
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Purpose: Conduct scientific experiments and observations in space, studying phenomena such as cosmic rays, radiation, and celestial bodies.
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Orbit: Scientific satellites can operate in a variety of orbits depending on their specific mission objectives. Some may be placed in low Earth orbit (LEO) for proximity to the Earth, while others may be positioned in higher orbits for broader observation.
Projectile Nature of a Satellite:
The motion of a satellite in Earth's orbit exhibits a projectile nature. A satellite, whether natural (like the Moon) or artificial, follows a curved path in space due to the gravitational influence of the massive body it is orbiting. Here are key points that highlight the projectile nature of a satellite's motion:
Gravitational Force:
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The primary force acting on a satellite is gravity. The satellite is continuously pulled toward the massive body (e.g., Earth), and this force is responsible for keeping the satellite in orbit.
Curved Trajectory:
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The satellite follows a curved trajectory as it orbits the massive body. This trajectory is determined by the gravitational force pulling the satellite inward and the satellite's tangential velocity preventing it from falling directly into the massive body.
Initial Velocity:
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For a satellite to enter orbit, it needs an initial velocity (tangential velocity) that is sufficient to counteract the gravitational pull. This initial velocity is essential to achieve a stable orbit without falling to the surface of the massive body.
Orbital Motion:
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The combination of the satellite's tangential velocity and the gravitational force results in an orbital motion. This motion is essentially a continuous projectile motion in a curved path.
Centripetal Force:
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The gravitational force acting on the satellite provides the centripetal force required to keep the satellite in its circular or elliptical orbit. The centripetal force is directed toward the centre of the massive body.
Zero Air Resistance:
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Unlike a projectile launched within Earth's atmosphere, a satellite experiences negligible air resistance in space. This absence of air resistance allows the satellite to maintain a stable orbit without losing energy to atmospheric drag.
Conservation of Energy:
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The satellite's orbital motion is governed by the conservation of energy. The gravitational potential energy is converted into kinetic energy, and the total mechanical energy (the sum of kinetic and potential energy) remains constant in the absence of external forces.
Kepler's Laws:
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The orbital motion of satellites follows Kepler's laws of planetary motion. These laws describe the elliptical nature of orbits, the equal area law, and the relationship between orbital period and semi-major axis.
SAMPLE PRACTICE QUESTIONS OF SIGNIFICANT FIGURES:
Q1 What is an Earth satellite?
Answer: An Earth satellite is an artificial object intentionally placed into orbit around the Earth for various purposes, such as communication, Earth observation, navigation, scientific research, and military applications.
Q2 How are satellites launched into space?
Answer: Satellites are launched into space using rockets. Once in space, they are deployed into their designated orbits.
Q3 What are the main types of Earth satellites?
Answer: The main types of Earth satellites include communication satellites, Earth observation satellites, navigation satellites, weather satellites, scientific satellites, military satellites, and more.
Q4 What is the purpose of communication satellites?
Answer: Communication satellites relay signals for television, radio, internet, and telephone communication, enabling global connectivity.
Q5 How do Earth observation satellites contribute to scientific research?
Answer: Earth observation satellites monitor and collect data about the Earth's surface, atmosphere, and oceans, supporting scientific, environmental, and military research.