Coming from a question about [distances between satellites in GEO][1], how are these distant satellites maneuvered and held in their orbital slots? I assume there is some propulsion system for each satellite, but what sort of fuel do they use? How long are they able to operate and adjust their orbital position?


  [1]: http://space.stackexchange.com/questions/2515/how-closely-spaced-are-satellites-at-geo