A 2025 study in the Journal of Space Science and Experiment assessed lunar ice-regolith extraction technologies. In tests near 400 W, an internal drill heat source recovered 40 g of water in 1 hour; the measured heat-absorption efficiency was only 8.4%, with an energy requirement of 8.6 Wh/g. Under microwave heating, recovery exceeded 90 g in 1 hour—more than twice the electrically heated result.[1]
The result identifies heat transfer through porous, cold regolith as the primary bottleneck for conventional heating. Microwave heating can improve extraction throughput, but system performance must be judged by collected—not merely released—water, because vapor transport, condensation, leakage, and power-conversion losses determine usable yield. A separate 2025 study reported microwave collection rates of 0.53–1.59 g/min, or 31.8–95.4 g/h, with collection efficiencies of 29.0%–59.5% across 2.0%–13.8% initial water content.[7] At 90 g/h, one unit would produce 2.16 kg/day continuously; meeting a 100 kg/day strategic reserve target would require at least 47 equivalent units before duty-cycle, maintenance, and environmental losses.[1]
The Ark team should prioritize microwave extraction and closed-loop vapor capture as an integrated technology, not treat the 40 g/h result as a flight-ready production rate. Monitor demonstrations that report specific energy in Wh/g, net collected-water efficiency, throughput versus ice concentration, microwave penetration depth, equipment degradation, and performance in vacuum and permanently shadowed-region simulants. Preserve the conventional drill-heater approach as a lower-complexity backup, but make microwave-assisted extraction the principal candidate for scalable polar resource processing.[1][7]