Why satellite needed to launched in prescribed height and orbit

[dijinj]

What are the reasons for satellite to be launched to outer atmospheric orbits... Is reduction in air friction a major reason, or is it just an added advantage. I know escape velocity has Major reason in it , what are other major reason for chosing particular orbit for a sate

 

[Flyboy]

It depends on what you want the satellite to do:

• If you want to do mapping work, you will almost always use a sun-synchronous orbit, going over the poles within a fairly low and narrow altitude range, which gives you the ability to revisit areas at the same time of day every day.
• If you want to keep your satellite over the same patch of ground at all times, you need a geostationary orbit, taking 24 hours to complete an orbit. Perfect for communication satellites, but also used for certain weather satellites that give you a picture of more than a third of the planet at once.
• Molnyia or tundra orbits are somewhat odd orbit in that they are semi-synchronous, i.e. they have a 12 hour period. They’re usually highly inclined as well to put their high points up over the polar regions. Originally pioneered by the USSR for their civilian communications satellites since it was both too difficult for them to achieve a proper geostationary orbit and because they are so far north that having a geostationary satellite is wasteful due to poor polar coverage.
• Mid-level orbits are used mostly for navigation satellites. GPS, GLONASS, Galileo, Beidu.

The higher the orbit, the lower the drag, and therefore the longer the expected service life without reboost. But they’re also more costly to access for a given payload mass, and provide lower sensor resolution for mapping work.

 

[dijinj]

It depends on what you want the satellite to do:

• If you want to do mapping work, you will almost always use a sun-synchronous orbit, going over the poles within a fairly low and narrow altitude range, which gives you the ability to revisit areas at the same time of day every day.
• If you want to keep your satellite over the same patch of ground at all times, you need a geostationary orbit, taking 24 hours to complete an orbit. Perfect for communication satellites, but also used for certain weather satellites that give you a picture of more than a third of the planet at once.
• Molnyia or tundra orbits are somewhat odd orbit in that they are semi-synchronous, i.e. they have a 12 hour period. They’re usually highly inclined as well to put their high points up over the polar regions. Originally pioneered by the USSR for their civilian communications satellites since it was both too difficult for them to achieve a proper geostationary orbit and because they are so far north that having a geostationary satellite is wasteful due to poor polar coverage.
• Mid-level orbits are used mostly for navigation satellites. GPS, GLONASS, Galileo, Beidu.

The higher the orbit, the lower the drag, and therefore the longer the expected service life without reboost. But they’re also more costly to access for a given payload mass, and provide lower sensor resolution for mapping work.

Thank you