These MARSIS 'radargram' images show echoes obtained from an approximately 250 km diameter circular structure in the subsurface of Mars, interpreted to be a buried impact basin. In both orbits, which are spaced about 50 km apart, MARSIS detected a series of arc-shaped reflectors that have no apparent source in the surface topography or geology.
In the lower image, a linear reflector nearly parallel to the surface is seen embedded in the arcs. This reflection may be coming from the floor of the basin. The time delay to the linear reflector suggests a depth of 1.5-2.5 km.