Mass-Constrained Integration of Cryogenic Propellant Management and Carbon–Hydrogen–Oxygen Resource Recovery for Mars Surface Depots: A Monte Carlo Feasibility Study

Manuscript (with Supplementary Information, cover letter and highlights) prepared for Acta Astronautica. A Mars surface propellant depot must make methane and oxygen, liquefy them and keep them cold on a limited launch mass, and each kilogram of added hardware displaces a kilogram of imported feedstock. Seven nested depot configurations (baseline; insulation with vapor-cooled shield; cryocooler; coordinated dispatch; gas and hydrogen buffers; titanium-hydride hydrogen store; buffers made from recycled material) are compared at equal launch mass (9 t, 30 kW array, 3 t methane and 10.5 t oxygen storage) by Monte Carlo simulation of 33 uncertain parameters (5 literature-anchored, 28 hypothetical), with paired comparisons on common random numbers, an independent energy-balance audit and out-of-sample stress tests. In the reference case the baseline holds 5,979 kg of usable propellant after one year and the integrated plant 9,005 kg; almost all of the gain comes from insulation, the vapor-cooled shield and the cryocooler (+1,533, +210 and +1,138 kg). Gas and hydrogen buffers change the delivered propellant by about +22 kg (0.2%), a hydride store lowers it by 44 kg against compressed storage, and recycled-material buffers change it by -1.3 kg; coordinated dispatch adds +122 kg (+4,547 kg against a strict-priority baseline). Screening-level simulation outputs under stated assumptions, not measurements; the thermal model has no pressure-resolved two-phase tank. Code, tests and results: https://github.com/sandlerleon/mars-depot-cho-propellant-mc