Preliminary design and performance assessment of a semi-autonomous global navigation satellite system on Mars

Over the last decades, several space agencies have increased their efforts in the design of future missions to Mars. To assist the operations of the upcoming missions, an infrastructure to support their navigation needs would be highly beneficial. In this scenario, we propose a configuration for a Martian navigation satellite system which ensures continuous and global positioning and timing services to users located everywhere on the planet and its vicinities, such as orbiters, rovers, and landers. We outline the constellation selection process and identify a suitable configuration of the system. The novel aspect of the proposed architecture consists in the use of intersatellite links between the constellation nodes, able to provide extremely accurate Doppler measurements and good positional accuracy in the known gravity field of the planet. Thanks to the intersatellite links, the need for ground support from Earth can be strongly reduced. To assess the performance of this configuration, a simulation of the orbit determination process of the constellation nodes is performed. Our results suggest that satellites can be positioned with respect to Mars with an accuracy at the level of 15 m with limited support from Earth. Finally, we evaluate the positioning performance of the end users located on the Martian surface. We show that a positioning accuracy as low as 20 m can be achieved (1-σ, 90 % of the time) with the proposed constellation.