The recent results by the Gamma Ray Spectrometer instrument on Mars Odyssey <Boynton et al., 2002> indicate the possibility of ground ice deposits within a few meters of the surface even at low latitudes and midlatitudes. The stability of ground ice deposits at these latitudes is a puzzling question. To address this question, we have developed the Berlin Mars Near-Surface Thermal model (BMST), a model for the thermal behavior of the Martian surface with a special focus on the volatile transport within the subsurface material. Using the BMST, we have performed a case study to derive limits on the burial depth of ground ice deposits stable over annual cycles at the MER landing sites in Isidis Planitia. We have studied the temperature gradient within the subsurface, assuming different structures and thermophysical properties for the surface and subsurface material. While the results derived here will have no immediate consequences for the MER mission because Isidis Planitia has been demoted to a backup landing site, the results show the potential and versatility of the model we have developed and give some results on the surface properties of Isidis Planitia.