MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is a low frequency, pulse-limited radar sounder and altimeter used on the ESA Mars Express mission. It features ground-penetrating radar capabilities, which uses synthetic aperture techniques and a secondary receiving antenna to isolate subsurface reflections. Its capabilities complement the SHARAD radar on the Mars Reconnaissance Orbiter.

MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is a low frequency, pulse-limited radar sounder and altimeter used on the ESA Mars Express mission. It features ground-penetrating radar capabilities, which uses synthetic aperture techniques and a secondary receiving antenna to isolate subsurface reflections. Its capabilities complement the SHARAD radar on the Mars Reconnaissance Orbiter.