Application of the drag-free control to low earth orbiting satellites

This paper describes the drag-free control approach and solution for a typical low Earth orbiting mission, along with its subsystems analysis and implementation. The considered drag compensation system is composed by an ultra sensitive accelerometer, electric thrusters and control subsystem. The Gravity field and Ocean Circulation Explorer mission is considered as case study. The modelisation of the non gravitational forces is referred to the 270 km height Dawn-Dusk orbit with the purpose of evaluating the necessary thrust levels required for drag compensation. On the basis of the environment characteristic, two electric thrusters technologies are investigated (Field Emission Electric Propulsion and Radiofrequency with Magnetic field Thruster) in order to find the most suitable one. The orbit control system is then analysed with respect to the Gravity field and Ocean Circulation mission system performance requirements and propellant mass consumption.