Exploration missions to the moons of the outer planets (such as Europa) pose unique challenges regarding the design of the spacecraft power source. Current aerospace qualified primary battery technologies cannot adequately meet the mass and volume requirements of proposed missions. Although they have not been used in prior deep space landed missions, lithium carbon-fluoride (Li/CFx) technologies were identified as a potentially viable option, both with and without blends of manganese dioxide (MnO2). To meet the performance requirements over the intended operating conditions of future NASA missions requires further development of this technology, in particular in the delivery of a high specific energy at moderate to low temperatures, and low discharge rates. A cell development effort was therefore pursued with an industrial battery cell manufacturer. Low (50 mA) and medium (250 mA) discharge rates were used to assess the performance of D-size cells under mission relevant conditions, between 0 degrees C and -40 degrees C. Select AA-size and C-size cells were also evaluated using similar rates scaled to the lower cell capacities. Developmental Li/CFx-MnO2 D-size cells designed for higher specific energy over these conditions were fabricated and tested, targeting operation between 0 and -40 degrees C and a 50 mA constant discharge current, as the baseline operating condition. (C) The Author(s) 2018. Published by ECS.