Re-Configurable Orbital Mirrors for Lunar Illumination

A space-based optical system is proposed to provide lunar surface illumination. The architecture has been analyzed from the perspectives of the photon flux, the spacecraft and attitude control system necessary to support the mirrors and orbital constellation. Three constellation options are considered, providing continuous coverage to the polar regions (constellation A), equator (constellation B) and entire lunar surface (constellation C). Light flux values are evaluated for all three options, with different mirror sizes and ground spot diameters. Illumination equivalent to Earth twilight, or better, can be provided to the lunar surface, depending on the configuration. Possible mirror designs may be rigid or flexible, and preliminary concepts are explored. The orbit maintenance costs are also considered, as well as slewing requirements which are found to be within state-of-the-art capabilities. The single layer constellations A and B offer simplicity and minimize elevation to polar and equatorial regions, respectively. Option C, with its two orbital layers, offers significant flexibility in both spot size and achievable total photon flux, while providing global lunar coverage, but at the cost of higher complexity and slewing costs.