HEXFlow Water Ice Expansion Hydraulics for Mars and the Moon

HEXFlow is a conceptual architecture in which the expansion of freezing water displaces a separate hydraulic fluid through a compliant separator. This white paper describes sealed diaphragm cells, supported microcell arrays, bellows, distributed hydraulic networks, and thermal switching arrangements for potential applications on Mars and the Moon. The leading research applications are small, slow, intermittent actuators and recovery of hydraulic work from water that must already freeze during processing or storage. The assessment addresses hydraulic routing, pressure containment, thermal reset, external collector and radiator requirements, accumulator behaviour, and planetary operating conditions. An illustrative screening calculation gives 90 mL of free-expansion displacement and 450 J of ideal hydraulic work from 1 L of water at a 5 MPa load difference, compared with approximately 334 kJ of latent heat required to melt the charge. Actual delivered displacement and useful work require measurement under load. The paper provides specific embodiments, reproducible calculations, references to earlier related work, original concept illustrations, and a staged validation programme beginning with a 10 mL water cartridge. All numerical examples are calculations; no HEXFlow prototype performance is reported. This conceptual public technical disclosure is intended to support further research, testing, adaptation, and collaboration.