Science Questions

How high are geostationary satellites?

Sun, 6th May 2007

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Question

Ray Mole, Sutton Coldfield asked:

When one of the space agencies places a Geostationary Communication Satellite into orbit, approximately what height are they positioned above the Earth? And how do they insure that they are released at exactly the right orbital velocity in order that the satellite remains in a totally geostationary position and what prevents them from drifting with time?

Answer

The height for geostationary orbit is about 22,300 miles, sitting directly above a fixed point on the equator.  They get to that height by being attached to the top of a rocket and launched at incredibly high velocities.  Itís taken years of practice to program the fine detail of controlling this into a computer, and small thrusters mounted on the satellite itself are used to manoeuvre the satellite into exactly the right orbit.  Drifting from the desired point is caused by the influence of the moon, and also by the fact that the earth is not a perfect sphere.  The small thrusters are used again to keep the satellite in the right orbit.

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