SATELLITE related General knowledge
What is satellite?
A satellite is an object which revolve around a planet. The revolution occur due to the effect of Gravitational Force that act between any two masses. There are two types of satellite one is natural satellite and other is artificial satellite. Natural satellites are created by nature and they are much bigger than artificial one. On the other hand artificial are man-made.
In our solar system Mercury and Venus has no natural satellite. Our earth has only one satellite which is Moon. Mars has two moon, Jupiter has 67 moons, Saturn has 62, Uranus has 27 and Neptune has 14.
The orbital speed of a satellite do not depend on its mass. This means if two or more satellites having different masses revolving in a same orbit will have same orbital speed. This speed depends only the distance between satellite and planet. If distance increases the speed well decrease.
If we place a satellite near the earth surface its speed should be 7.9 km per second.
Russia was the first to send satellite into the space on 4 October 1957, Name of the satellite was Sputnik 1.
Geostationary Satellite :
Geostationary satellites are kept at high altitude, about 36,000 km above the earth surface. Main characteristics of this satellite is that it will remain at the fixed position with respect to earth. This means it has same angular velocity and direction with 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 passes over equator once in a single day. They are kept about 700 km above the earth surface. They are used mainly for mapping purpose.
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 moon its value is 2.4 km/s. If Ve is the escape velocity, g is gravitational acceleration and R is the radius of planet then, –
Ve = √(2gR)