Abstract: The Earth's outer atmosphere at the low altitude causes a significant drag on the spacecraft such as scientific detection and Earth observationsatellites in super low earth orbit, furthermore the atmospheric drag changes in a wide range along with solar activity, geomagnetic activity, seasonal and diurnal cycle. In order to meet the demands for satellite orbit accuracy or flight conditions, this drag needs to be continuously or intermittently compensated by onboard thrusters. Considering drag free flight and orbit maintenance at an altitude of about 220~268km, the variety of atmospheric drag and the specifications of the spacecraft payloads were analyzed, and then the researches were carried out on the technical parameters, thrust throttling approaches, system architecture, thrust control project and onorbit application strategy of ion propulsion. Accordingly thrust throttling tests were executed .The results show that ion propulsion should operates over a thrust range of 1~20mN with the thrust resolution of 12μN, and over a thrust range of 1~25mN with the thrust resolution of 100μN for drag free and orbit maintenance mission respectively.The technical project of ion propulsion is valuable for application reference of satellites in super low Earth orbit. 

Key words: satellites in super low Earth orbit, drag free flight, orbit maintenance, ion propulsion, continuous thrust throttling