Ice-covered ring
Bare, sublimed ring
Beam footprint (1σ)
The 3D orbital view of a statite mirror swarm tracks a single number: the whole polar cap's mass, shrinking as one lumped reservoir. This 2D companion instead resolves the cap radially — 48 independent rings, each with its own ice thickness and temperature, each balancing absorbed mirror flux against Stefan–Boltzmann radiative loss and lateral conduction to its neighbors every step. When a ring's energy balance would push its temperature past the CO₂ frost point, that ring is pinned there and the excess energy is spent on latent heat instead, sublimating real mass off that ring alone — the same Stefan-condition bookkeeping that governs any real melting or subliming surface. Watch the depletion front spread outward from wherever the mirror swarm's aim angle actually focuses the beam, and see a bare, warmed regolith ring emerge once its ice is gone while its outer neighbors are still untouched.