A. Cicchetti

Mars ionosphere data inversion by MARSIS surface and subsurface signals analysis

According to the Mars Express mission , the MARSIS primary scientific objectives are to map the distribution of water, both liquid and solid, in the upper portions of the crust of Mars. Moreover three secondary objectives are defined for the MARSIS experiment: subsurface geologic probing, surface characterization, and ionosphere sounding.

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.

Subsurface Investigations by MARSIS in Mars Express Mission

The analysis of the surface return echoes in the subsurface data extraction in North Mars Polar region has shown the possibility to utilize simplified surface models, at least, for the purpose of the evaluation of the penetration depth capability. The surface simulation, obtained starting from MOLA data, has been utilized during the planning activity in order to select the MARSIS operative sequence in order to optimize the amount of scientific data taking into account the data rate available and the scientific target to be investigated during the next part of the mission. Moreover a simulator, still in progress, utilizing the surface characteristics will perform the analysis of the real data in order to make available the required information expected, by the mission, in terms of detection and identification of dielectric constant on the surface and subsurface.