Abstract
With the ever-increasing lunar missions, a growing interest develops in
designing data relay satellite constellations for cislunar communications,
which is challenged by the constrained visibility and huge distance between the
earth and moon in pursuit of establishing real-time communication links. In
this work, therefore, we propose an age and coverage optimal relay satellite
constellation for cislunar communication by considering the self-rotation of
the earth as well as the orbital motion of the moon, which consists of hybrid
Earth-Moon Libration 1/2 (EML1/L2) points Halo orbits, ordinary lunar orbits,
and Geostationary Earth Orbit (GEO) satellites. In particular, by minimizing
both the number of satellites and the average per-device Age of Information
(AoI) while maximizing the coverage ratio of specific lunar surface regions, a
multi-objective optimization problem is formulated and solved by using a
well-designed Nondominated Sorting Genetic Algorithm-II (NSGA-II). The
simulation results demonstrate that our proposed hybrid constellation
significantly outperforms traditional Walker Star and Delta constellations in
terms of both AoI and the coverage of communication.