re: Marsis "results"
It sounds like they are having trouble figuring out exactly what the data means.
This paragraph I think means they need to be closer to Mars at night to get good data:
While the Mars Express point closest approach is in daylight, MARSIS is only operating at higher frequencies within its capability because the lower-frequency radio signals get disturbed. With these higher frequencies, MARSIS can study the ionosphere and the surface, while some shallow subsurface sounding can still be attempted.