As new lunar exploration and development plans heat up, proposals for a lunar navigation system are also on the agenda. According to the South China Morning Post on July 14, Chinese scientists have come up with a plan to build a Beidou navigation system-like communications and navigation constellation capable of serving the full moon. Earlier, the United States, Europe and Japan have proposed their own lunar navigation plans. So what are the challenges of building a lunar navigation system?
Chinese scholar proposes lunar navigation plan
Citing a paper published in June in the Chinese Journal of Space Science and Technology, the South China Morning Post said, the Chinese research team considered various indicators such as relay communications, lunar navigation, constellation construction and maintenance costs, and proposed a near-lunar space navigation constellation consisting of 21 satellites, the goal is to provide long-term, high-density navigation for human activities on the Moon.
NASA’s“Moon Net” architecture provides navigation and communications services near the Moon.
According to the South China Morning Post, currently on the Earth’s surface or in near-earth space, using mainly American Global Positioning System (GPS) , Chinese Beidou Navigation System, European Galileo and Russian Glonass, for the global user to provide all-weather, high-precision positioning and navigation services. These GNSS usually consist of 20-35 satellites with precision up to a few metres, and users can use a combination of at least four satellites for precise positioning and acquisition of time information.
Chinese scientists have proposed a similar lunar navigation scheme, which requires at least four satellites to be visible to the target at the same time. Reported that the study also proposed a near-moon space constellation construction route, in three phases to gradually achieve the full-moon navigation. The Chinese research team said that follow-up studies will combine orbital parameter optimization techniques to form a more systematic lunar navigation scheme.
The report said that although the paper did not give a specific timetable for construction, but initial plans for China’s Lunar Exploration Program and plans for an international lunar research station have already been announced: China plans to send astronauts to the Moon by 2030, with the Moon’s South Pole as the core by 2035, an international lunar research station with basic functions and supporting elements will be built and expanded by 2045.
The United States, Europe and Japan have proposed lunar navigation plans
In recent years, the construction of near-lunar space constellation is becoming a hot research direction in space. With more and more lunar exploration and development activities, the idea of establishing lunar navigation system has been proposed. To meet the navigation needs of the US’s “Artemis” manned lunar mission, scientists on a NASA Jet Propulsion Laboratory in 2020 calculated that, gPS satellite signals are still available 380,000 km away near the moon, and it is claimed that spacecraft in lunar orbit can pick up signals from 5-13 GPS satellites with positioning accuracy of between 200 and 300 metres.
But if large-scale exploration and development activities are to be carried out on the lunar surface, such positioning accuracy will not be enough. The global satellite navigation system (GNSS) , which operates near the Earth, has a signal strength of only one-thirtieth that of the Japan Aerospace Exploration Agency on the Moon, 380,000 kilometers away, according to the JAXA report, and because the moon itself is occluded, the far side of the Moon can not pick up these navigation signals. At the same time, the Moon’s surface is covered with craters, and weak navigation signals from Earth are easily blocked by hills and crater edges, requiring specialized communications satellite to support them. China already has successful experience in lunar communications relay, with the Magpie-1 and MAGPIE-2 satellites, launched in 2018 and 2024, providing relay communications support for a number of lunar missions.
In 2020, NASA proposed a “Moon Net” to support the Artemis program, which would allow for communication between astronauts and spacecraft on and near the Moon’s surface, it also allows astronauts and Rovers to get position and time information from the rugged lunar surface. To that end, NASA launched the Lunar Communications Relay and navigation system in January 2022, with plans to launch multiple satellites in lunar orbit. June 28,2022, the United States“Top stone” detector launched. The microwave-oven-sized probe is billed as the“World’s first lunar navigation satellite,” and one of its missions is to validate and test new navigation technologies to reduce the risks of future missions.
Europe is also pushing ahead with plans for lunar communications services. In 2021, the European Space Agency Agency (ESA) launched the “Moonlight” initiative, which proposes a shared lunar communications and Navigation System -LCNSLCNS) with sustainable services around the 2027, and plans to launch the first“Lunar pathfinder” satellite in 2025, in elliptical frozen orbit to carry out technical verification.
In 2022, the Japanese JAXA also proposed the lunar navigation satellite system (LNSS) , which plans to deploy eight satellites in lunar elliptical orbit to provide relay communications and navigation and positioning services to probes in the lunar south pole region.