Histograms of the roughness angle in the region of interest (a) before and (b) after the landing. The modes of the histograms are indicated by the red vertical lines. Before the landing, the mode and mean of the background pixels are 14.7 and 17.5 degrees, respectively. Background: mode after the landing: 12.6 degrees; mean after the landing: 17.2 degrees. Landing site: mode after the landing: 11.6 degrees; mean after the landing: 13.4 degrees. The two distributions after the landing for the landing site and background have a KS-test score of D = 0.436 with p = 1.78 × 10⁻¹⁵.