With an increase in Lunar exploration activity expected in the 2030s through the Artemis program as well as other governmental and private missions, infrastructure architectures are essential to enable ambitious robotic and human surface missions. Beyond the Lunar Gateway, service stations, and payload landers, high-reliability and high-accuracy navigation and communication (NAVCOM) services are a critical requirement for all Lunar surface assets. Such services enable high-precision landings, guidance for robotic/human rovers exploring unknown terrain, and a reliable and high throughput connection to long-term human habitats. This paper aims to explore the tradespace of a constellation combining NAVCOM services around the Moon. The key research question addressed in our work is the impact of the semi-major axis, the number of orbit planes, and the number of satellites per plane of a circular frozen orbit Walker constellation on the NAVCOM performance. The figures of merit (FOMs) of the analysis include the coverage with a Geometric Dilution of Precision (GDOP) below 6, a theoretical constellation capacity, and the power flux density coverage for a Lunar orbit to Lunar surface S- and Ka-Band connection. Results indicate that minimum sets of satellites at a minimum distance from the Moon are required to fulfill global coverage and adequate performance for the NAVCOM service. In addition, it is identified that certain combinations achieve a particularly poor GDOP coverage in the equator region. From the tradespace analysis, a set of parameters is then selected for further study based on a combined performance assessment of the FOMs. Based on this selection, an exemplary NAVCOM constellation is derived, including a concept of operations, detailed navigation and communication architectures, and a satellite bus design. This 21-satellite Walker constellation can provide coverage of close to 100% with a GDOP of less than 6.0. With a regenerative communication design, it provides close to 100% surface time for both S-and Ka-Band and a Ka-Band relay to Earth, following guidelines proposed in the LunaNet standards. This work aims to serve as a basis for further studies into Lunar communication and navigation constellations for Lunar frozen orbit Walker constellations and provides a starting point for one of the fundamental prerequisites of an extended Lunar presence.
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With an increase in Lunar exploration activity expected in the 2030s through the Artemis program as well as other governmental and private missions, infrastructure architectures are essential to enable ambitious robotic and human surface missions. Beyond the Lunar Gateway, service stations, and payload landers, high-reliability and high-accuracy navigation and communication (NAVCOM) services are a critical requirement for all Lunar surface assets. Such services enable high-precision landings, gu...
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