Since the beginning of this century, gravimetric missions have started to become one of the most interesting topics in the field of space research. The reason behind the growing attention paid to this type of missions is certainly to be found in its ambitious objective, which is the accurate measurement of the temporal variations of the Earth gravity field. As a matter of fact, the observation and monitoring of these variations could improve the understanding about some geophysical processes involving Earth’s mass change phenomena. The concept of Next Generation Gravity Mission (NGGM) has been proposed by ESA with the aim to raise the bar on the work started by the previous gravimetric missions, like GOCE and GRACE.