Sounding Mars with SHARAD & MARSIS

MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is a low frequency nadir looking sounding radar selected by ESA as a payload of the Mars Express mission, whose primary Scientific Objective is to map the distribution of water both solid and liquid, at global scale on the Martin crust. MARSIS is the first instrument to be able to detect what lies beneath the surface of Mars (up to about 5Km). The Mars Shallow Radar Sounder (SHARAD), a facility instrument provided by the Italian Space Agency (ASI), is embarked on board the NASA Mars Reconnaissance Orbiter spacecraft. SHARAD began science operations on October 3rd 2006: it has been collected data from surface and subsurface. This instrument penetrates to roughly half a kilometre below Mars´ to search for information about underground layers of ice, rock and, perhaps, melted water. In this paper, some interesting comparisons between these sounders are proposed. Data confirm that MARSIS and SHARAD are complementary instruments.