Beacons for Improving Lunar Landing Navigation

Abstract

Since the beginning of human space exploration, safe and soft landing on a celestial body (planet, moon, asteroid) has been a central objective. Starting from the first landings on the Moon, which had generally a precision above 1 km, today improvements in the navigation architecture and filters have made it possible to improve the final accuracy and increase the safety. The more exploration missions land on a planet the more resources on the ground can be made available for further missions. The potentially first implementation of co-located ground infrastructure is probably a robotic lunar base which will be followed by a human base. For both some studies have been done in the past and are still ongoing. The scenario of a robotic or manned lunar base is used as a motivation to investigate the impact of ground infrastructure to the navigation system of later arriving landing and potentially also departing vehicles. The paper presents a state-of-the-art navigation system architecture for planetary landers and introduces additional possible measurements from ground based infrastructure to support navigation. This extended architecture is based on the usage of ground beacons providing radio frequency (RF) based measurements. As an example a lunar landing scenario is introduced as a reference mission for the analysis of the effect of the ground beacons. Current navigation requirements for landing vehicles are established and an evaluation function is defined. Simulation results are presented first for a baseline navigation system without beacon support. Then the results for different beacon configurations with one or more beacon are presented. For the configurations a grid of potential positions with respect to the target landing site is analyzed and evaluated. Finally, the results from all test cases are discussed and a recommendation for beacon locations is given.