Investigating the effects of geometric and environmental parameters on the governing equations of scanning earth horizon sensor and attitude determination error analysis

This study is performed to estimate the error of solving governing equations of a dual-cone scanning earth horizon sensor in presence of geometric and environmental parameters. In the process of extracting the equations for determining the sensor’s attitude, firstly, a simplified form of the earth as an sphere without atmosphere is used to model the earth and compared with the governed attitude of simulated satellite on a hypothetical orbit. But in reality, the geometric factor of the earth oblateness and environmental factors such as the sensor's field of view, the effect of the atmosphere and its reflection from the earth's surface cause errors in attitude determination of the satellite. Therefore, by assuming that the sensor is mounted on a satellite, simulating motion in a near earth orbit and modeling the sensor, the sensor’s inlet pulse and the amount of roll and pitch angles in different geometric and environmental conditions are calculated. Then, by comparing the calculated attitude with the simplified case, the effect of each in the occurrence of error are obtained. The simulation is based on a dual-cone scanning earth horizon sensor made in the Institute of Mechanics of Iranian Space Research Center on MicroMAS satellite. According to the simulation results, the atmosphere radiation and surface reflection, earth oblateness and sensor FOV in roll angle and in pitch angle, earth oblateness, atmosphere radiation and surface reflection and sensor FOV are the most effective factor in revealing error respectively.