A Study of Satellite Navigation, Dilution of Precision, and Positioning Techniques for use on and around the Moon

The National Aeronautics and Space Agency is examining several approaches to meet navigational requirements for spacecraft in lunar orbit, in transit to or from the moon, and for personnel on the lunar surface requiring an accurate, real-time, on-board navigation capability. This work addresses one possible solution to the navigation problem in the vicinity of the moon using a lunar satellite navigation system. Dilution of precision is the figure of merit used to determine if a candidate lunar satellite navigation system can meet accuracy specifications based on a given satellite constellation and the measurement types used. Ten satellite constellations, using two measurement types (direct ranging and time-difference-of-arrival), are analyzed for numerous user locations on the moon. Using terrestrial and Earth-orbiting assets to augment the lunar constellations is also investigated. Sensitivity analyses are accomplished to determine the effect on the position solution accuracy of additional measurements, reduced measurements, and different combinations of measurement types