Halo orbit dynamics and properties for a lunar global positioning system design

In this paper, the use of north and south families of halo orbits, around the L 1 and L 2 collinear libration points of the Earth–Moon system, to realize a lunar global positioning system (LGPS) is proposed. The computation of the reference trajectories and the required station-keeping manoeuvres with the associated ΔV are described, as well as different configurations for the satellites’ constellation. The combination of the north and south families of halo orbits results in an X-shaped configuration allowing optimal performances. A visibility study, from different locations on the lunar surface, has been performed together with a performance analysis in terms of availability of the LGPS signal and quality of the position solution, resulting in a candidate architecture able to guarantee the availability of the LGPS service at the scientifically interesting lunar poles. In addition, the proposed constellations are also interesting from a connection point of view, assuring continuous communication capabilities between the Earth and every location on the surface of the Moon, as well as between any of the points on the ground.