Regenerative ECLSS and Logistics Analysis for Sustained Lunar Surface Missions

As NASA develops concepts for sustained crew missions to the lunar surface, a crucial component of mission planning will be evaluating the required amount of logistics to support the crew, surface systems, and science operations. This amount could be substantial. Because NASA plans to conduct these missions on an annual basis, the complexity and cost of logistics delivery will likely drive campaign sustainability. Logistics quantity is partially a function of the regenerative Environmental Control and Life Support System (ECLSS) capability in habitable elements on the surface. The regenerative ECLSS recycles human waste to produce water and oxygen, reducing the consumables needed for a mission. Thus, an ECLSS with increased regenerative capability will require less logistics. However, an ECLSS with enhanced regenerative abilities will also increase the initial delivery mass of elements and require extra maintenance items and spares. This paper analyzes the tradeoff between initial delivery masses of different regenerative ECLSS options and the amount of logistics resupply required for each option. Sustained lunar surface missions will involve crews of two to four astronauts living on the surface for periods of 30 days or longer. Astronauts will live in some combination of a surface habitat and/or a pressurized rover. To conduct the study, the authors created the Lunar Surface Integrated ECLSS Analysis Tool to model different configurations of rover and habitat with different ECLSS options. The tool can simulate ECLSS operations in the integrated architecture, including potential commodity transfers between the habitat and the rover. In this paper, the authors describe the use of the tool to evaluate different possible ECLSS configurations and their corresponding logistics requirements. The authors then complete a sensitivity analysis that compares logistics requirements for annual resupply and the initial delivery mass over increasing regenerative ECLSS capabilities. Finally, the authors recommend ECLSS architecture options that potentially improve the balance between logistics requirements and ECLSS system mass.