LEO is short for Low Earth Orbit Satellites.

As the name suggests, LEO satellites are closer to the Earth than traditional satellites.

There are four types satellite orbit.

The four types are:

Low Earth Orbit

Medium Earth Orbit

Geosynchronous Orbit

Geostationary Orbit.

Let’s first look at Geosynchronous and Geostationary satellite orbits.

A satellite in a Geosynchronous orbit will only be ‘visible’ once a day.

This is because the Geosynchronous satellite does not stay in a fixed location, in relation to the earth’s surface.

Therefore Geosynchronous satellites are best suited to data-gathering applications, such as weather satellites.

Data-gathering applications, only need to download data periodically.

This means that not being in continual transmission contact with a ground station on earth, is not important.

Geostationary satellites effectively rotate with the Earth.

This means that they are over the same landmass at all times.

Geostationary satellites are suitable for continuous contact with a fixed area of Earth.

An example of their use is for satellite television.

The distance from Earth in geostationary orbit is 35790 km.

Medium earth orbit satellites are often shortened to MEO.

Medium Earth Satellites, are at a distance from the earth, between the high and low range of orbits.

The distance of a MEO satellite from the Earth is between 1200 – 35790 km.

So finally let’s look at what are LEO low earth orbit satellites.

Let us remind ourselves that LEO stands for Low Earth Orbit.

LEO orbits are closest to the earth of the satellite orbits used.

Typically a LEO orbit is between 500 – 1000 miles from the earth.

In kilometres, this is 800 – 1600 km.

So let’s look at the characteristics of LEO satellites.

As satellites in LEO are closer to the Earth, they need less rf transmission power.

Another advantage is being closer to the earth, the radio signals have less distance to travel.

This results in less latency.

Latency is the delay in the radio signal travelling between the ground station on the earth, and the satellite in space.

For modern applications such as video conferencing, you want latency to be as small as possible.

This is because you don’t want delay, as it will affect two-way communications.

LEO satellites are being put into space in huge numbers, by companies such as Starlink and OneWeb.

By having lots of these cheaper smaller LEO satellites in linked ‘constellations’, you can achieve worldwide communications coverage.

Published by Craig Miles

Craig Miles

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