Subsurface sounding in Northern hemisphere for Mars by MARSIS: Mars express mission

The MARSIS observations are optimized during periods when the pericenter of the orbit is near or below zero degrees sun elevation (ldquonightsiderdquo) and the nightside phase, the last of the primary MEX mission, occurs on March-July 2005, in the northern latitude of MARS regions. This paper provides a description of the modeling approach and of the expected performance of the MARSIS radar in the northern hemisphere of Mars. Few models, suitable for a preliminary analysis of the MARSIS instruments are reported. The knowledge of these performance, evaluated according to the model used for the surface and subsurface of the Martian crust, are necessary in order to decide, during the planning activity of the mission, the radar operative mode. In addition the model utilized are an effective tool for the simulator that has to perform the radar equation inversion in order to evaluate, by the radar returns, the surface and subsurface dielectric characteristics. Few simulation results of the surface characteristics are reported and a radar gram is shown, as an example, in order to state the preliminary criteria for the radar equation inversion.