Radar Exploration of Mars: Recent Results and Progresses - Planetary Exploration and Science: Recent Results and Advances - page 85

Fig. 5.6 MARSIS and SHARAD north pole radargrams

Fig. 5.7 Boundary, 700 m deep, in Dorsa Argentea ridge area

As mentioned before, Mars Express orbits are highly elliptic, and MARSIS
operative window extends at each pass for about 40 min as the spacecraft altitude is
less than 1,200 km. This characteristic gives the opportunity to study not only the
subsurface of the Red Planet but also its ionosphere. Radar sounders already proved
to be useful in the ionospheric physics study when applied to Earth ionosphere.