In this paper, a high integration gain GEOSAR mission for Earth imaging is presented. The spatial-temporal atmospheric decorrelation issues of a long integration time GEOSAR mission must be carefully studied. The feasibility of a GEOSAR mission for Atmospheric Phase Screen retrieval purposes is studied. The raw data received from several hours of acquisition is divided into sub-acquisitions with integration time on the order of the APS decorrelation time. From each sub-matrix, a low-resolution but enough to sample the spatial variations of the atmospheric map is obtained. The simulated results of the APS retrieval from a GEOSAR acquisition are shown at the end of this paper.Peer Reviewe