Originally Posted by
wiggy
Thanks, for that, wiggy. As you say, the geostationary belt is quite full. As has been mentioned, there is potential for interference if the geo satellites get close, but there is also a risk of collision, especially when you consider that some satellites stop operating and there's nothing you can do to move them, so you have to move others out of the way. Then there's whatever some company or country used to get their satellite into that orbit and might have been discarded.
One other thing to consider is that I suspect most people think that a satellite in geostationary orbit is stationary relative to someone on Earth. They aren't. Although they generally stay within a belt and close to where they should be, they actually do all sorts of loops and strange shapes while staying close to their supposed position from an Earth-observer's perspective. Considering all that, ground-based telescopes are used to detect if any operational satellites are in danger of collision and if they are, the ground-based observations are used to let the various companies know when and where to move their satellites.
A lot of work goes on behind the scenes to keep the world in touch!