Space Systems/loral, LLC

Yassir Azziz

Xen Price

Darren R Stratemeier

Jorge Delgado

Saghir Munir

David Cielaszyk

Rob Schwarz

Justo Jacinto

Alicia Kavelaars

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.

Satellite orbit raising using electric propulsion

Estimation of a desired antenna tracking profile is provided for a radio frequency autotracked (RFAT) antenna in the absence of a ground reference. A first RFAT antenna subsystem has a first antenna and a first antenna positioning mechanism (APM), each mounted on a vehicle, and a first ground-based RF beacon; a second RFAT antenna subsystem has a second antenna and a second APM, each mounted on the vehicle, and a second ground-based RF beacon. A controller stores an accumulated record of actuations of the second APM as a function of time under normal operation, calculates a desired antenna tracking profile for the second antenna, from a first ground-based RF beacon and from the accumulated record, excluding any real-time data from the second ground-based RF beacon, and transmits actuation commands to the second APM so as to cause the second antenna to track the desired antenna tracking profile.

Antenna tracking profile estimation

Growing community of inventors

San Mateo, CA, United States of America

Yassir Azziz