Spaceborne Gravity Gradiometer: Ways To Improve the Accuracy of Earth's Gravity Field Models

Results of analysis for improving the space resolution of Earth's gravity field static models and monthly models by optimizing the orbital parameters (major semiaxis and inclination) of a spacecraft with an onboard gradiometer that is in low-earth orbit are reported. Requirements to the orbits of a spacecraft that will be involved in an advanced gradiometric mission have been worked out. Numerical simulation has made it possible to find the elements of a spacecraft orbit that allow 100% coverage of the Earth's surface by measurements (subsatellite tracks) with a space resolution of 0.3 degrees x 0.3 degrees. Such a resolution is twice as high and better than that of the Earth's gravity field static models that were obtained in the GOCE mission data. The orbital configurations found allow construction of monthly models of the Earth's gravity field with a space resolution of 0.9 degrees x 0.9 degrees, which is four times better than the resolution of models obtained in the GRACE mission. Instrumental requirements to main measuring equipment to be used in a forthcoming space gradiometric mission have been estimated.