Left: Kolmogorov-Smirnov distance d between the observed distribution of η and those calculated as a function of thermal inertia for the four roughness scenarios. In all cases, a uniform distribution of the polar axes over the sphere is assumed. The minimum of d indicates the best fit thermal inertia Γ₀. Right: histograms showing the distribution of best fit Γ₀, when accounting for uncertainties in the η measurements (see text).