Polar Orbit & Clarke Orbit
Polar Orbit
The Polar Orbit is not much suitable for communication purposes because it moved in a different direction than that of direction of earth’s rotation. So, the use of Polar satellites depends upon their arrival at a particular point on earth at a particular point. The Polar orbits are used for special applications like navigational satellites.
Clarke Orbit
Please note that a single geostationary satellite can view approximately one third of the Earth’s surface. If three satellites are placed at the proper longitude, the height of this orbit allows almost the Earth’s entire surface to be covered by the satellites. It was first of all conceptualized by world famous science fiction writer Arthur C. Clarke. The arrangement which was suggested by Clarke is shown in the following figure:
The stations would be arranged approximately equidistantly around the earth and the following longitudes appear suitable:
- 30°E – Africa & Europe
- 150°E – China & Oceania
- 90° W- The Americas
The station chain would be linked by radio or optical beams and thus any broadcast service could be provided. The geostationary orbit is now sometimes referred as the Clarke Orbit or the Clarke Belt in his honor.
Other Orbits
- Super synchronous orbit is a disposal / storage orbit above GSO. From earth, they would seem drifting in westerly direction.
- Sub synchronous orbit is a orbit close to but below GSO and is used for satellites undergoing station, changes in an eastern direction.
- Graveyard orbit is a Supersynchronous orbit where spacecraft are intentionally placed at the end of their operational life.
