This paper discusses the algorithm of coarse sun acquisition with sun sensors only for micro satellites. The developing FormoSat 7 constellation is employed as the application and example of this algorithm. Unlike a larger satellite, the power in a micro satellite is limited. Therefore, an attitude estimator is usually not functioned at the launching stage. After the stage of detumbling, the micro satellite has to acquire sun as soon as possible with the designated algorithm. In this paper, an algorithm to perform blind search of sun is developed only with coarse sun sensors. We also consider the eclipse of the sun. A 6DOF model is developed and Monte Carlo simulation method is employed to verify the developed algorithm. The developed algorithm will later be applied to the FormoSat 7 constellation, and can be used in any micro satellites with similar equipment.
