The Ganymede Circular Orbit Phase (GCO-500) of the JUICE mission will be the first time a moon beyond Earth’s will be orbited for an extended period of 9 months. This orbit phase, due to its close proximity, opens the window to more accurately determine the spacecraft orbit and thereby unambiguously characterize the interiors of the Galilean moons. Ganymede is believed to harbor an internal ocean and will help understand the habitability of icy worlds in the outer solar system. In this study results of a sensitivity analysis are presented which investigate the settings of a model developed for the GCO-500 phase. The model aims to realistically emulate the JUICE mission concept, by specifically focusing on the radio science experiment 3GM, responsible for estimating the gravity field. The model also includes non-gravitational accelerations which are accounted for by the High Accuracy Accelerometer (HAA).