How Do Satellites Stay In Orbit?

To be able to watch satellite TV with such a small receiver means the Satellite must remain in exactly the same position.

As the earth is revolving at just over 1000 mph the satellite must also have a 24 hours turning period like the earth.

A satellite's radius must be 42164km and the earth's radius is 6378km that means geostationary satellites are placed at 35768km from the Earth's surface.

Satellites must also be kept on the Earth's equatorial plane otherwise the sat would display a figure of 8 pattern across the sky. The satellite must also be kept in a circular orbit to maintain distance from the Earth.

But this causes problems in that the Earth is not perfectly sphere.

The gravity from the Sun and Moon affect the satellite. Even the pressure of sunlight can also affect it.

Engineers are able to adjust the satellite about once every 14days to bring it back to its favoured 1 degree position.

This manoeuvre is done with tiny jets the size of match sticks.

The amount of fuel used in these manoeuvres dictates the life of a satellite.

Once the fuel is gone, after up to 13 years the satellite makes one final manoeuvre, and sends its self hurtling in to deep space.

Perhaps one day to transmit to an alien race!