The MOMS-2P system, an advanced high resolution 3-line stereo scanner for Earth observation, will fly on-board the MIR space station (1996), augmented by a navigation package. The navigation information, required for the reconstruction and evaluation of the collected images, is provided by a GPS receiver. The aim of the research is to implement and validate a completely new concept, which combines the orbit determination and image reconstruction process to improve the accuracy of stereoscopic image products. Emphasis will be on the precise orbit determination of MOMS, fully exploiting the GPS carrier-phase and pseudorange measurements complemented by groundbased GPS measurements, in a differential GPS (DGPS) approach. In contrast to the well-known kinematic Earth based DGPS approach, a dynamical modelling of the spacecraft motion is required. By adopting the proposed DGPS approach, the orbit determination accuracy is expected to improve from 100-200 m to better than 5 m, eventually enabling us to better monitor our world.