Mapping Earth's gravity in space: Review and future perspective

The distribution of earth’s gravity field not only changes along with the altitude, latitude, crustal composition and mantle depth, but also varies together with the continental drift, glacier evolution, ocean current, underground water changing and phenomena of ice and snow. Therefore, the scientific data of earth’s gravity field is essential to many research fields, such as the geological hazard monitoring, geodetic survey, glaciology, hydrologic circle, solid earth physics and national defense. The measurement, recovery and application of gravity of earth were greatly promoted by the development of gravity satellite missions, for example the GRACE (Gravity Recovery And Climate Experiment) mission. In order to improve the temporal and spatial resolution of satellite gravity data, China, USA and European countries were considering launching upgraded gravity satellite missions, namely the GRACE-follow-on mission. The basic idea is to employ the laser interferometer
measurement system to replace the GRACE’s microwave ranging system. In addition, the drag-free technics is introduced to eliminate the disturbance of non-inertial
forces posed upon laser measurement system. A brief history of the development of gravity satellite missions and the earth gravity recovery techniques were reviewed here. The measurement methodology, key technologies and expected results of next generation GRACE mission were also slightly touched upon.