Abstract: A spacecraft includes at least a first thruster support mechanism (TSM) and a second TSM, each TSM including a pointing arrangement, an elongated structural member and thruster for performing orbit raising north-south stationkeeping, east-west stationkeeping, and momentum management. A first pointing arrangement is articulable only by way of first and second revolute joints, the first revolute joint being rotatable about a first axis fixed with respect to the spacecraft. The second pointing arrangement is articulable only by way of third and fourth revolute joints, the third revolute joint being rotatable about a third axis fixed with respect to the spacecraft. The first axis and the third axis are asymmetrically arranged with respect to a spacecraft coordinate system origin such that the first and third axis are at acute angles to a spacecraft pitch axis and the acute angle of the first axis is less than that of the third axis.

Abstract: Methods and apparatus for a spacecraft (1) orbiting about a celestial body such as the Earth to reacquire operational three-axis orientation with respect to that body.

Abstract: Payload performance is optimized by determining yaw trajectory employing a method which develops a mathematical expression to define the payload in terms of ‘n’ location(s) on the earth; determining the pointing error of the ‘n’ location(s); combining the error so as to product a single performance parameter and minimizing the value of the performance parameter by appropriately varying yaw.

Abstract: A continuous three axes satellite pointing system for a solar powered satellite, the system comprising a body control module for producing three orthogonal axes body control torques, a momentum integration module, a momentum control module, and a program torque decoupling module. The program torque decoupling module de-couples the programmed motion parameters represented by the equation: IB&ohgr;′+B&ohgr;X(IB&ohgr;+BH).

Abstract: An attitude or orientation control system for spacecraft that provides for yaw axis error reduction and momentum dumping using a simple calculation involving only the momentum wheel speeds as input and which outputs two axis (roll and yaw) torque commands. The system utilizes the spacecraft 1) momentum wheels that store spacecraft momentum, 2) processing means for the calculation of control torques, and 3) torque actuators, e.g., magnetic torquers, that can provide a torque axis anywhere in the spacecraft roll/yaw plane, and involves three fundamental steps, 1) the input of the momentum wheel speed mearsurements, and 2) the calculation of the required torques, using the wheel speed measurements, and and 3) the outputting of the required torques in a form appropriate for controlling the available actuators.