Question

At what height does the Geostationary satellites revolve?
$\text{A}\text{.}$ any height
$\text{B}\text{.}$ fixed height
$\text{C}\text{.}$ height above pole
$\text{D}\text{.}$ height which depends upon its mass

Answer 1

- Hint: Here, we will proceed by firstly discussing the geostationary satellites. Then, we will mention whether the height at which these satellites are revolving. Then, we will discuss the advantages and limitations of these satellites.

Complete step-by-step solution -

A geostationary satellite is an earth-orbiting satellite, placed at an altitude of approximately 35,786 kilometres directly over the equator, that revolves in the same direction the earth rotates (west to east). At this altitude, one orbit takes 24 hours, the same length of time as the earth requires to rotate once on its axis. The term geostationary comes from the fact that such a satellite appears nearly stationary in the sky as seen by a ground-based observer.
A single geostationary satellite is on the line of sight with about 40 percent of the earth's surface. Three such satellites, each separated by 120 degrees of longitude, can provide coverage of the entire planet, with the exception of small circular regions which are centred at the north and south geographic poles. A geostationary satellite can be accessed using a directional antenna, usually a small dish, aimed at the spot in the sky where the satellite appears to hover.
The principal advantage of this type of satellite is the fact that an earthbound directional antenna can be aimed and then left in position without further adjustment. Another advantage is the fact that because highly directional antennas can be used, interference from surface-based sources, and from other satellites, is minimized.
Geostationary satellites have two major limitations. First, because the orbital zone is an extremely narrow ring in the plane of the equator, the number of satellites that can be maintained in geostationary orbits without mutual conflict (or even collision) is limited. Second, the distance that an electromagnetic (EM) signal must travel to and from a geostationary satellite is a minimum of 71,600 kilometres.
Therefore, these satellites revolve at a fixed height (i.e., approximately 35,786 kilometres).
Hence, option B is correct.

Note- About 35,786 kilometres above the Earth’s surface, satellites are in geostationary orbit. From the centre of the Earth, this is approximately 42,164 kilometres. While the geostationary orbit lies on the same plane as the equator, the geosynchronous satellites have a different inclination.