The curiosity to know about space has brought humans to the point from where they can think of going to another planet. And the role of satellite in all this has been incomparable.
India may have been slow in this direction earlier but now it has just picked up its pace. ISRO is one of the top space agencies in the world today.
In this article, we will mainly discuss the types of satellite, its use and the satellites left by India in a simple and easy way, so read the article till the end.
What are satellites ?
A satellite can be a celestial body or a machine that orbits a planet or star. For example, the Earth can be called a satellite because it revolves around the Sun. Similarly, the Moon is a satellite as it orbits the Earth. Apart from this, many machines made by humans, which are sent to space for a particular task, are also satellites.
Earth and Moon are examples of natural satellites. Whereas the machines which are sent by humans into space are called artificial or man-made satellites. Man-made satellites are made to meet different needs, such as some are made for taking pictures and some for weather forecasting and navigation etc.
| History of Satellites in India
People’s curiosity towards space has been there since ancient times and this curiosity kept increasing from generation to generation. When this growing curiosity became a necessity, it was not known and now it is a part of life.
Some countries have really put flags in the fields of space research. Well India has also come to this area sooner or later and now India is also raising flags in this area.
The space program in India started with the formation of the Indian National Space Research Committee in 1962 under the chairmanship of renowned space scientist Dr. Vikram Sarabhai . The establishment of the Sounding Rocket Launching Facility Center at Thumba, Kerala in 1963 is considered an important step towards India’s space programme. On 21 November 1963, India launched its first rocket ‘Naik Apash’.
On August 15, 1969, this Indian National Space Research Committee was reorganized and the Indian Space Research Organization, which we today call ISRO ( ISRO ) ;
The Space Commission and the Department of Space were formed in 1972 to give an independent existence to space research. On 19 April 1975, a satellite named Aryabhata was sent into space as an experiment and after that ISRO never looked back and today ISRO is one of the top space agencies in the world.
Today in this article we will know how many types of satellites are there, but as we know that satellites revolve in the orbit of the earth, that is why it is important to know about the orbits of the earth here.
| Earth orbits
There are mainly three types of Earth orbits: high earth orbit , medium earth orbit, and low earth orbit .
The altitude region from 160 to 2000 km above the surface of the earth is called low earth orbit . The altitude region ranging from 2000 km to about 36000 km is called medium earth orbit . The orbital region of 36,000 km and above is called high earth orbit .
Overall, the meaning of saying here is that whenever a satellite is released, it will be sent to any of these orbits. The satellite sent in the high orbit of the earth is stationary, that is, whenever we see it from the earth, it will always appear to us located at the same place.
In fact, a satellite in a high orbit completes one revolution of the earth in 24 hours, and in the same time the earth also makes one revolution on its axis; This is the reason why a satellite in this orbit appears stationary from the earth.
Satellites sent in low orbit and medium orbit – the earth so fast that they are not visible continuously at a fixed point in the sky. A low orbit satellite makes one orbit around the earth in about 90 minutes. Whereas a medium orbit satellite takes 2 to 8 hours to make one revolution around the earth. A low earth orbit satellite orbits something like this;
type of satellite
On the basis of the position of the satellites , it can be classified into the following parts;
| Sun-synchronous satellite
A Sun-synchronous satellite is a satellite in the Lower Earth Orbit, which is located at an altitude of 1000 km below the Earth. This type of satellite always arrives at the same place at the same local time – for example, if a sun-synchronous satellite is seen passing over Delhi at 10 o’clock in the day, it will again be in Delhi at 10 o’clock the next day. will appear above. Usually it rotates in a special type of polar orbit from north to south direction, hence it is also called polar satellite;
| geo-stationary satellite
These satellites orbiting in the high orbit of the Earth, about 36,000 kilometers above the equator, complete one revolution in the direction of the Earth’s motion (west to east) in about 24 hours.
A single geostationary satellite can cover about 40 percent of the Earth’s surface. Three such satellites, each separated by 120 degrees of longitude, can provide coverage of the entire planet.
| geo-synchronous satellite
It works in the same way as geo-stationary satellites, only it has some inclination. As you can also see in the picture below.
- On the basis of function, satellites can be divided into the following types;
| Communication satellite
Communication satellite is a very important man-made satellite, it transmits and amplifies radio telecommunication signals through a transponder. Actually, a transponder is a device installed in a satellite that also receives and transmits the signal.
For example, suppose a program is broadcast by a TV channel, first its signal will be received by the transponder installed in the satellite and then it will be transmitted to the earth. It will be received by an earth-mounted dish antenna.
Communication satellites are placed in geostationary orbit so that they always send signals targeting one part of the earth. The advantage of this is that the dish antenna does not have to be rotated again and again, rather it is fixed in a particular direction and left and it continues to work. Communication satellites are used for telephone, radio, Internet and military applications in addition to television.
So far more than 45 communication satellites have been launched by India, if you want to know about all the satellites then you can see on ISRO’s site.
| Scientific Satellite
Scientific satellites are used for research and research purposes. With its help, data on phenomena related to the magnetic field, space radiation, Earth and its atmosphere, Sun or other stars, planets and their moons, and other celestial bodies are obtained and used in necessary research work. Such as NASA’s Parker Solar Probe and ISRO’s Aditya L1 which is related to the study of the Sun.
| Weather Satellite
Earth satellites that study atmospheric conditions for meteorological information are called weather satellites. Such satellites can be of polar orbit and also geostationary.
The instruments in these weather satellites have the ability to obtain meteorological information even beyond the clouds. Apart from this, it also provides information related to other phenomena such as city lights, fires, effects of pollution, sand and dust storms, ice cover and ocean currents etc. India’s Insat 3D is one such satellite.
| Remote Sensing Satellite
Remote sensing means to get detailed information about any object or phenomenon related to that site without any physical contact or visiting that site. Remote sensing technology is used in many fields, such as land surveying, military and intelligence gathering, commercial and economic sectors, and other humanitarian applications. When similar work is done by a satellite then it is called remote sensing satellite .
When a signal is propagated by a satellite to an object on Earth and its image is received by the sensor, it is called active remote sensing. But when the reflection of sunlight is detected by the sensor then it is called passive remote sensing. India’s Cartosat-1 is one such satellite.
| Marine Satellite
The Marisat satellites provide navigation and directions to seafarers by radio signals in every hour of distress. With such satellites, they can contact the sailors of other ships and their headquarters as well.
| Navigation Satellite
Navigation satellites are those satellites which make our life easier by providing daily needed information like live traffic, distance measure, live location etc.
It is usually a group of several satellites that provide navigational information on a regional or global scale. As for GPS, it is a global navigation satellite operated by the US.
The Google Map we use is based on GPS. India also has some such satellites, which you can see below?
| GPS Aided Geo Augmented Navigation (GAGAN)
Its name is a bit long but it is known as Gagan. Gagan is used in the field of civil aviation. It provides satellite based navigation services with the required precision and reliability. The main objectives of GAGAN are to provide better air traffic management in the Indian airspace.
| Indian Regional Navigational Satellite System (IRNSS) : NAVIC
Like America’s GPS, it is India’s own local GPS system. As the name suggests, regional; This bus has been made focusing on India and not the whole world. Its operational name i.e. the name used is NavIC – NAVigation with Indian Constellation.
It is designed to provide high-end navigation features and is capable of providing accurate real-time positioning. It is still working successfully but it is not yet fully available for public use. [ Learn about IRNSS NaVic in detail ]
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