The present thesis work focuses on the search for an appropriate thruster configuration, suitable for the Next Generation Gravity Mission (NGGM). The goal of the NGGM mission is to measure the temporal variation of the gravitational field in the Earth’s system. Following the success of the previous GOCE and GRACE missions, the NGGM one is intended as the Earth Observation mission of the future. The main technological innovation introduced, concerns the exploiting of the laser interferometry technique, between satellite pairs, to collect data with an unprecedented spatial and temporal resolution. As a monitoring mission, the NGGM formation needs to fly at relatively low altitudes (of around 350 km), where the presence of the atmospheric drag is not negligible, for a long period of time (of around 7 years, according to the current scientific requirements).