Analysis of the accuracy of Earth remote sensing satellite angular motion control and track guidance during route observation intervals

Abstract

The article deals with problems associated with determining permissible accuracy of Earth remote sensing satellite control over observation intervals taking into account the interaction of optronics and charge-coupled devices with time-delay and integration (CCD TDI). The control accuracy requirements are determined for the condition that the allowable image shift value should not be exceeded. The allowable accuracy is proportional to the time of exposure of a resolution cell which depends on the number of CCD array storage rows and image motion velocity. The discrepancy between the image motion velocity supported by the optronics and the Earth surface scanning velocity depends to a large extent on the satellite control accuracy regarding its angular position and rotation about the centre of mass. Angular motion over observation intervals is formed based on the condition of constant specified longitudinal velocity and zero transverse velocity of image motion relative to the frame centre. The dependence of the frame-centre image shift value on the spacecraft angular motion control system follow-up errors is determined. Based on the obtained relation, an algorithm of determining allowable angular motion follow-up errors is proposed. The angular motion follow-up error influences the accuracy of the optronics optic axis pointing at the central route line. The article gives examples illustrating application of the proposed algorithm as well as assessment of en-route targeting accuracy.

Keywords

• earth remote sensing satellite
• angular motion
• targeting
• attitude error
• angular velocity error
• optical system
• exposure interval
• image motion rate
• image shift