Flow over the ice sheet surface before freezing halts movement. Created using known and conjectured thermophysical properties of solid and liquid N₂ (Table 1) as input values with local slope θ = 1°. Left panel: radial flow distance r_f before freezing. Right panel: duration of flow before freezing t_f. Vertical dashed lines correspond to a reference discharge rate Q_m = 25 m³ s⁻¹ (see discussion, in Section 4.5). Freezing times shown in this figure range from ~0.02 to 200 hr depending on viscosity and injection rate of the flow. We use η for the dynamic viscosity of solid N₂ ice, distinguishing it from the dynamic viscosity μ of liquid N₂.