SATELLITE ORBIT RAISING USING ELECTRIC PROPULSION

Apparatus and methods for raising the orbit of a satellite having electric propulsion thrusters, an Earth sensor and an inertial reference sensor such as a gyro. A satellite positioning system generates orbital data and a profile generator generates an ideal electric orbit raising profile of the satellite. The ideal profile is one that the satellite must follow so that the perigee, apogee and inclination of the satellite can be adjusted simultaneously in a mass-efficient manner. A state machine processes the ideal profile and a true anomaly to generate a desired electric orbit raising profile. Steering apparatus generates signals that are used to control the attitude of the satellite to follow the desired profile. The desired profile places the satellite in an Earth-pointed attitude when the satellite is at a predefined point in the orbit, slews the satellite from the Earth-pointed attitude to an ideal orbit raising attitude, steers the satellite according to the ideal profile during orbit raising, and steers the satellite from the desired attitude to the Earth-pointed attitude.