Spaceborne Push-Broom Image Guidance, Attitude Realization Errors: A System Engineering Approach

During the preliminary phase of a satellite system design, a complete model of the satellite may not be available due to the uncertainties in the design. As a remedy, a simple methodology based on system engineering approach may be used to rapidly determine pointing requirements to initiate requirement analysis phase of the satellite design. For this purpose, the effects of the pointing accuracy and stability requirements on the spaceborne image acquisition are identified for the push-broom sensor applications. Further, image guidance algorithms are identified to obtain proper attitude profiles which are used in line of sight analysis. To determine the relationship between the geometrical properties/requirements of the images and the pointing requirements, line of sight analysis is carried out and implications for the selection of the specifications of the electro-optic payload equipment are discussed. Moreover, a simplified mathematical model is established in order to determine satellite stability requirement related to the scan speed of the electro-optic payload equipment. The method is applied to an Earth observation satellite with a push-broom electro-optic sensor which has a sub-meter level ground sampling distance. The presented analysis should also be of interest to optical Earth observation satellite system mission analysis and general satellite design, particularly attitude and orbit control sub-system design.