Authors
MATTIA CRESCENZO IMPERATO (CIRES), Khosro Ghobadi-Far (CIRES), Steve Nerem (CIRES)

Abstract

Future gravity field recovery missions are expected to benefit from the rapid development of spaceborne optical atomic clocks. Unlike traditional gravity missions such as GRACE, GRACE-FO, and GOCE, which measure spatial derivatives of the gravitational potential, orbiting optical clocks enable direct sensing of geopotential differences through gravitational redshift measurements. By exploiting Doppler-canceling frequency shift (DCFS) measurements between distant clocks, fractional frequency differences can be directly related to geopotential variations, establishing a linear relationship between observations and geopotential coefficients and simplifying the gravity field inversion process. This measurement concept also relaxes the geometric constraints imposed by traditional inter-satellite ranging missions, enabling the exploration of more flexible formation-flying architectures. In this work, several optical clock–based satellite formations beyond the traditional GRACE-like configuration are investigated, including Cartwheel, Helix, and Pendulum architectures, and their performance for gravity field recovery is evaluated. These configurations provide complementary sensitivity directions, improving observability of the disturbing potential. Simulation results further show that formations introducing cross-track and radial sensitivity, such as Helix, Cartwheel, and Pendulum configurations, achieve improved recovery performance compared to traditional along-track architectures, particularly in the detection of time-variable gravity signals. Overall, the results highlight the importance of formation geometry and multi-directional sensitivity enabled by optical clock measurements, suggesting that advanced formation-flying architectures could significantly improve gravity field recovery capabilities for next-generation geodetic missions.