Numbers of rays received as a function of the orbiter location and Δh values for five different values of Δϵ. The location of the orbiter is east of the landing site for a) and west for b). The configurations leading to no signal are shown in dark blue; those corresponding to a high number of rays (multipath scenario) are plotted in yellow and red. The vertical red lines show the angular positions of the orbiter during FSS-E and FSS-W.