Electric propulsion for satellites

EE September 1986 ELECTRIC PROPULSION FOR SATELLITES by Dr Anthony Martin, Culham Laboratory, Abingdon, Oxfordshire. Fuel is a significant fraction of a communications satellites mass. A large part of it is needed for the rockets which keep the spacecraft stationary in Most commercial satellites are destined for geo- stationary Earth orbit. That is, an orbit with a period of 24 hours, which means the satellite rotates about Earth at the same rate as Earth revolves about its axis. The satellite will then appear to be fixed in the sky, so the antennas receiving its signals do not have to be steered or moved to track it. The greater part of Earth"s long-range communi- cations are now routed this way, including inter- continental telephone calls, and television from the other side of the world is familiar on our screens. Plans are already well advanced for direct broadcasting satellites which will relay signals with such a high power that they can be picked up by a relatively small di...