<p>One significant obstacle to the colonization of Mars is the high cost of excess launch mass required for long-term space travel and the establishment of a settlement. The Sabatier reaction provides a means for recycling water and rocket propellant that dramatically reduces the supplement. Herein, we introduce a membrane Sabatier system by integrating a catalytic reactor with an H₂O vapor permselective membrane tube. We achieve a substantial increase in CO₂ conversion, a high CH₄ yield and excellent long-term stability via highly efficient in-situ water removal. Furthermore, the system’s robustness under intermittent power supplies, and its adaptability across a wide range of reaction conditions, makes it highly compatible with the electrolytic hydrogen production system, which is subject to unstable solar energies. The advent of the membrane Sabatier system heralds a transformative approach to the recycling of H₂O and rocket propellant in long-term interplanetary exploration.</p>