Thermal inertia versus grain size R (top panels) or heliocentric distance D (bottom panels), considering the crystalline ice (left panels) or amorphous ice (right panels) forms. Porosity is fixed at p = 0.5, bolometric Bond albedo A = 0.5 and emissivity ϵ = 1. Both tight (full line) or loose (dashed line) contacts are considered in each case. Data from Table 2 are plotted. Mimas data are plotted as a black symbol for both R₁ (trailing) and R₂ regions. The best fit of Γ(D) with the data is plotted also (dot line, see text).