By Carolyn Mercer, NASA Glenn Research Center, Cleveland, OH
NASA is focused on building a human outpost on the lunar surface. To reach this goal, there is a critical need to develop energy storage technologies to power the future lunar outpost. In particular, technology is required for outpost power generation for the lunar lander that will deliver outpost hardware, and for advanced extravehicular activity (EVA) suits. In every case, human-safe, reliable operation and low mass are critical to ensure the viability of extended stays on the lunar surface while minimizing the launch mass and the mass carried by astronauts and lunar rovers.
Lunar outpost energy storage requirements include providing energy for habitats, mobility systems, in-situ resource utilization, communications and navigation, and science experiments. In each of these cases, human-safe operation, reliable operation, and high specific energy are required. For relatively shortduration applications, the use of batteries is envisioned with a target specific energy goal of 200 Watt-hours/kg over the temperature range of 0 to 30°C. For longterm, continuous operation, regenerative fuel cells are envisioned with a target lifetime of 10,000 hours of maintenance-free operation and a 56% system efficiency, producing nominally 3 kW per module in a 0-30°C and 0-1/6 gravity environment operating with reactants pressurized to nominally 2,000 psi.
Batteries for the Altair lunar lander’s ascent stage require nominally 10 recharge cycles with 1.7 kW nominal power and 2 kW peak power, operating for seven hours continuously. The Altair descent stage requires a fuel cell with a nominal power level of 3 kW with 5.5 kW peak, operating for 220 hours continuously. Mission priorities include human-safe, reliable operation, the ability to scavenge available fuel, and high energy density.
EVA suits require rechargeable batteries sufficient to power all portable life support, communications, and electronics for an 8- hour mission with minimal volume. Battery operation is required for six months and 100 recharge cycles with a shelf life of at least two years. The total energy required to complete the 8- hour mission is about 1,200 Watthours, with battery mass and volume goals of no greater than 5 kg and 1.7 liters. This energy must be provided over the temperature range of 0-30°C and be safe enough for human rating.
To address these needs, NASA is developing lithium-based battery technology and protonexchange- membrane fuel cell technology. Specific areas of investment include the development of high-performance battery components including anodes, cathodes, electrolytes, separators, and safety devices. We are developing advanced stacks and balance-of-plant technology for fuel cells and regenerative fuel cells, as well as membrane electrode assemblies and cooling technology targeted for low-mass, ultra-reliable operation.
For more information, or to tell us about your ideas, contact NASA Glenn Research Center at 216-433-3484.