A Phase-Change Thermal Wall for a Lunar Habitat: Diurnal Storage Mass, Thickness and Temperature Stabilisation

This paper presents a computed design for a phase-change material wall that melts during the lunar day and freezes at night, absorbing and releasing heat at nearly constant temperature instead of relying entirely on active cooling. The study is simulated, not measured. Using the stated assumptions in the Methods and the deposited calculation, the headline results are: mass = 833, thick = 1.2, Q = 180. All quantities are derived in the accompanying script, which writes the full numerical record to results.json, including inputs, outputs and, where relevant, a parameter sweep. The design is assessed on its computed performance, its mass and power budgets where relevant, and its failure behaviour. Where the computed result is impractical, that outcome is stated plainly in the abstract's terms as well as in the Discussion: the numbers, not the intention, decide whether the principle is attractive at the stated scale. No measurement of a built system is reported, and no flight performance is claimed.