ALL ABOUT ARTIFICIAL AND NATURAL SATELLITES
A satellite is an object whether natural or artificial, orbits a star or a planet in space. An artificial satellite or a man-made satellite is a satellite or machine which is sent to space and which moves around the earth or other objects in the space. Sputnik-1 was the first man-made satellite sent to space on 4th Oct 1957 by the Soviet Union.Artificial satellites collect geographic information and also it manages the Tv signals, Radio signals, Phone call signals, calculates the percentage of atmospheric gases like(carbon dioxide, ozone, nitrogen, oxygen etc).Nearly 20 satellites are engaged for GPS system globally. Artificial satellites help in tracking frequencies of the natural disaster such as hurricanes, Tornado, Tsunami, Cyclone, Flood etc.
Natural satellites are naturally created in space that goes around a planet and so they are categorized as natural satellites. For example, Earth and Moon are natural satellites because the earth orbits the sun, and the moon orbits the earth. There are thousands of artificial satellites (man-made) launched till now that orbits the earth and collects geographical images and data, which helps Meteorologists in predicting natural disasters and weather informations.
Artificial satellites play a very important role in the field of communication. When there was no satellite system in the past, the signals of Tv, Radio and Phone calls didn't go very far. Due to mountains and tall buildings, the signal loss was a frequent problem during that old days. And also the cost of setting up underground wires and cables were too costly. But now, due to the advancement of technology, we can manufacture a satellite and can launch it into the space for managing Tv, Radio, and Phone call signals. The camera that a man-made satellite uses for taking pictures of earth and other objects in space uses a wide angle lens for a wider view. It can take a good quality wide picture in comparison with other cameras that we use on earth in our day to day life. When we use a Telescope for viewing into space, the visuals that we see are not so clear to our eye because of dust particles and dense clouds. But in case of man-made satellites due to very high altitude positioning, a satellite can take or record a clear image/video without any visuality issue. Presently NASA has more than a dozen satellites (scientific satellites) which collect and sends atmospheric & geographic data.
Parts of satellites can differ from each other. Satellites are manufactured with different size and shape according to their purpose of use, Functionality etc. Different satellites with different functionality are equipped with different scientific instruments like Camera, Sensors, Softwares etc. But they have at least two basic parts common in all. The first one is the antenna, which sends and receives signals. Another part is a solar power or a battery power system, by which the whole satellite gets power to work and move. The satellites orbit the earth when it is in its balanced state. After placing the satellite in its given orbital axis (Geostationary or Polar), it only orbits the earth properly when the speed of it gets lower and balanced by the Earth's pulling gravity.
A geostationary satellite always moves in the Earth's direction of rotation and at the same speed rate of the earth in its equatorial plane. Geostationary satellites move in the direction from West to East. But the polar satellites move in the direction from North to South with respect to the pole to pole. Polar satellites revolve around the earth in its polar orbit. Polar satellites orbit the earth vertically while the geostationary satellites orbit the earth horizontally around the earth's equatorial plane. Some examples of Polar satellites are IERS and SPOT. TESLAR was the first geostationary satellite or a communication satellite.
There are currently thousands of satellites present in the space, which orbits the earth and other planets. Here the chance of collision between them is very rare on practical or theoretical basis because the positioning of each satellite is unique and different from each other inside the orbit. Though the change of orbit for any satellite could be very dangerous. But this natural phenomenon is very rare, however on Feb 2009 two geostationary satellites collided with each other in space for the first time. With new inventions and refinement of technologies in the field of space research, these space accidents can be avoided with ease.