SATELLITE related General knowledge
What is satellite?
A satellite is an object which revolves around a planet. The revolution occurs due to the effect of the Gravitational Force that acts between any two masses. There are two types of satellite one is natural satellite and the other is an artificial satellite. Natural satellites are created by nature and they are much bigger than the artificial ones. On the other hand, artificial is man-made.
In our solar system, Mercury and Venus have no natural satellite. Our earth has only one satellite which is Moon. Mars has two moons, Jupiter has 67 moons, Saturn has 62, Uranus has 27 and Neptune has 14.
The orbital speed of a satellite does not depend on its mass. This means if two or more satellites having different masses revolving in the same orbit will have same orbital speed. This speed depends only on the distance between satellite and planet. If the distance increases the speed will decrease.
If we place a satellite near the earth’s surface its speed should be 7.9 km per second.
Russia was the first to send a satellite into space on 4 October 1957, Name of the satellite was Sputnik 1.
Geostationary Satellite :
Geostationary satellites are kept at high altitudes, about 36,000 km above the earth’s surface. The main characteristic of this satellite is that it will remain at a fixed position with respect to earth. This means it has the same angular velocity and direction with the earth. It’s time period or time of revolution is 24 hour. Therefore if it is possible to watch this satellite from our earth, it would be always visible. The orbit in which this satellite revolves is called Geosynchronous orbits.
Polar orbits Satellite :
These satellites revolve around north-south poles and pass over equator once in a single day. They are kept about 700 km above the earth’s surface. They are used mainly for mapping purposes.
Escape Velocity :
Escape velocity is a certain velocity by which an object can escape from a gravitational field. Therefore if we project a body from earth surface with escape velocity it will never return to earth again. For earth, the value of this escape velocity is 11.2 km per second.
Escape velocity is totally independent of its mass, size density, and direction of projection. For a particular planet, the escape velocity is fixed for all objects. For the moon, its value is 2.4 km/s. If Ve is the escape velocity, g is gravitational acceleration and R is the radius of the planet then, –
Ve = √(2gR)