Contents: What is satellite? About Satellite Communication Classification of Satellite Communication Kepler’s laws
What is satellite? A Satellite is a solid object which revolves around some heavenly body due to the effect of gravitational forces which are mutual in nature. The first satellite that was used for communication purpose in INDIA was ARYABHATTA and it was launched in 19th April.1975. It was made and assembled by an organization called Indian Space Research Organization (ISRO). In the year 1981, a satellite named APPLE was launched in space which was the first Indian Experimental communication satellite
Classifications: SATELLITE ACTIVE SATELLITES PASSIVE SATELLITES NATURAL ARTIFICIAL
Active Satellite: Active satellites are complicated structures having a processing equipment called Transponder which is very vital for functioning of the satellite. These transponders serve dual purpose i.e. provides amplification of the incoming signal and performs the frequency translation of the incoming signal to avoid interference between the two signals.
Passive Satellite: Passive satellites are relay stations in space. A passive satellite can be further subdivided into two types, namely Natural satellites and artificial satellites. A moon is a natural satellite of earth. But spherical balloon with metal coated plastic serve as artificial satellites.
History of Kepler Johannes Kepler was a German astronomer and mathematician of the late sixteenth and early seventeenth centuries. His work was largely based on the work of his mentor, Tycho Brahe. Kepler was able to use Bahe's precise measurements (made before telescopes) to determine, mostly by trial and error, three laws that described the motion of the five planets then known.
Three laws of Planetary Motion: Law of orbit Law of areas Law of Time period
Law of orbit: The orbit of a planet/comet about the Sun is an ellipse with the Sun's center of mass at one focus This is the equation for an ellipse:
Law of Area: A line joining a planet/comet and the Sun sweeps out equal areas in equal intervals of time.
This empirical law discovered by Kepler arises from conservation of angular momentum. Thus, a planet executes elliptical motion with constantly changing angular speed as it moves about its orbit.
Law of Time Period: The squares of the periods of the planets are proportional to the cubes of their semimajor axes: Ta2 / Tb2 = Ra3 / Rb3 Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit. Thus, we find that Mercury, the innermost planet, takes only 88 days to orbit the Sun but the outermost planet (Pluto) requires 248 years to do the same.
Graph showing time taken by each Planets to orbit the sun