The moon’s harsh thermal environment presents challenges for engineers as they develop a lander capable of operating continuously for six years on the lunar surface. The project’s mission concepts push the boundaries of flight-proven power systems, and the power subsystem team is testing batteries to determine their thermal limits. While mission concepts differ in their power requirements, engineers are testing for the most severe operational case. Solar array/battery combinations could be used for some mission concepts, while others require an Advanced Sterling Radioisotope Generator (ASRG). With either power system, engineers must test battery chemistries to ensure the lander can meet the mission requirements.
Engineers are testing to determine the batteries’ operational boundaries. Testing began in summer 2010 at NASA’s Marshall Space Flight Center and will yield results in battery longevity, maximum temperature operation, and depth of discharge. The project team is testing lithium cobalt oxide battery cells for a solar array/battery mission concept, and it is testing lithium iron phosphate cells for an ASRG mission scenario.
Because the spacecraft battery is the most sensitive component of the warm electronics box, the thermal and power subsystem teams must work closely to ensure that risk reduction activities meet objectives for both subsystems.