Energy storage selection and operation for night-time survival of small lunar surface systems

Abstract In the coming decade, a multitude of small, carry-on payloads in the form of miniature rovers, scientific instruments and surface deployed stand-alone systems will provide many new and exciting possibilities for lunar exploration. For these system, the survival of and operation in the extreme cold of the lunar night will be the biggest challenge, as most will be purely battery driven and unable to rely on radioisotope heaters. Maximizing battery lifetime in these conditions requires a trade-off between energy density, low-temperature performance and insulation, but comparable temperature and current dependent discharge capacities of batteries and other energy storage devices are often not reported in datasheets or literature. For this reason, a selection of energy storage devices was chosen and tested to determine their low-temperature performance in a representative environment. Based on this data, the theoretical lifetime per battery weight and optimal operational temperature for varying degrees of insulation was determined. It was shown that the selection of the optimal energy storage device and operational temperature depends on the insulation, emphasizing the need for multi-disciplinary design optimization.