7.1.3C Geostationary Orbit

What does the view from the Electro-L, a geostationary satellite look like? Check out this video!

Well, the Earth looks like it has stopped rotating. That’s because we are on a geostationary satellite! The satellite is orbiting in the equatorial plane at the same angular velocity as the rotational speed of the earth. So the Earth looks stationary from the satellite, and the satellite looks stationary from the Earth.

Geostationary orbits are perfect for communication and broadcast satellites. Because a GEO satellite remain at the same spot in the sky, ground antennas do not have to track its movement across the sky, but instead just point permanently at its position in the sky.

A geostationary orbit can only be attained at an altitude of close to 36,000 km. From such high altitude, it takes only 3 GEO satellites to provide coverage for the majority of the Earth surface.

satview2

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However, the polar regions will always be out of reach from the GSO. Since the GEO satellites orbit in the equatorial plane, they are always below the horizon at lattitudes above about 81°.

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Being so far from Earth, the time taken for a signal to travel between Earth and the satellite is a few hundred ms. This poses problems for latency-sensitive applications such as live voice calls.

(sources: images from http://www.rap.ucar.edu/~djohnson/satellite/coverage.html)

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