Space around this planet, and in particular the region that geostationary satellites inhabit, is not a vast and limitless void. A key attraction of these slots is that one can communicate with the satellites without interfering with nearby satellites. Slots in geostationary orbit lie along the equatorial belt, each about 370 km wide. More than one satellite can occupy the same region in space, but they must communicate with their ground stations in different portions of the radio spectrum. The so-called Luxemburg cluster of at least five geostationary satellites is an example of such sharing allowed by the International Telecommunications Union, Geneva, Switzerland.
Geostationary satellites tend to drift over time from their appointed positions in space.
Ground controllers must periodically fire thrusters on the satellite to counteract the effects of the sun and moon and nonuniformities in the earth's gravitational field. The armchair analyst can follow this by observing small variations in the satellite's longitude over a year. If a country wants to change the orbital position of a satellite, it fires the satellite's thrusters to produce a change in velocity. The Russians moved Cosmos 2133 at the phenomenal speed of 1.7 degrees per day, which corresponds to a change in velocity of 20 meters per second, followed by an equivalent thruster burn to stop it when the satellite reached its new position. For comparison, Western owners of geostationary satellites typically assume that one year of satellite lifetime is lost for every degree per day it is moved.