Future space exploration missions will require new and innovative approaches to supplying electric power. Due to the very high transportation cost associated with the lunar and Mars missions, the mass of these power systems will be a critical factor. Power systems currently being considered for these applications include both nonnuclear and nuclear systems.For lunar applications, the 354-hour-long nighttime presents a formidable challenge to energy storage technology for nonnuclear power systems. Because of their low energy densities, energy storage systems can be prohibitively massive at higher power levels. Consequently, the nonnuclear power systems may be limited to low-power mission applications on the surface of the Moon. Eliminating or greatly reducing the need for energy storage makes these systems competitive with nuclear power systems.A Free Electron Laser (FEL) power system based in lunar orbit was examined for providing power by beaming energy to the lunar surface. The FEL power system was compared with surface-based nuclear and nonnuclear power systems over a range of user power requirements. Preliminary results show the laser power beaming system to be increasingly competitive on a mass basis with the nonnuclear power at power levels above 50 kWe. However, compared with a surface-based nuclear power plant, the laser beaming power system is an unattractive option unless, for some reason, a nuclear plant cannot be situated on the lunar surface.