Feasibility of Scavenging Propellants from Lander Descent Stage to Supply Fuel Cells and Life Support

A feasibility study consisting of both analytical and experimental work was performed to determine if the lunar lander vehicle can use residual propellants remaining in the descent stage tanks after landing to provide reactants to the fuel cell power system and oxygen to life support for a 7-day sortie mission. Initial results indicate that the residual hydrogen will last approximately 19 days at the poles and 15 days at the equator. The residual oxygen will last 21 days at the poles and more than 16.5 days at the equator. Excess hydrogen will need to be vented during the mission to prevent tank over-pressurization, while heat must be added to the oxygen tank at the poles. Tests performed on a liquid oxygen tank pressurized with helium demonstrate that the helium concentrations in the ullage gas can be reduced significantly with venting. Tests on a flow-through fuel cell stack indicate that they can tolerate significant amounts of helium contamination in the reactants without permanent