“I call LunaNet the big umbrella,” Gramling says. “It’s an architecture that defines the standards that will be used for interoperable communications, positioning, navigation, and timing services. There’s a lot of work going on to define those standards and document them in the LunaNet interoperability specification.”
“It’s a completely different paradigm than on Earth, where the US has GPS, Europe has Galileo, and Russia has GLONASS,” he adds. “Because we’re in the early stages, the idea is that we have to work together as the three partners who have been involved in LunaNet so far and provide one system out of the three of us.”
In other words, while NASA, ESA, and JAXA are currently working on their separate projects, they plan to eventually combine these ideas into a single operational system. The detailed plans for ESA’s Moonlight Initiative are helpful in imagining what a lunar GNSS constellation could ultimately look like.
Under ESA’s current vision, Moonlight will consist of at least five satellites, including a vast communications satellite and four smaller dedicated navigation satellites, placed in special orbits to optimise coverage of the lunar south pole. This initial configuration will provide 15 reliable and predictable hours of PNT services in the coverage area every 24 hours, but Moonlight is also designed to be scalable, meaning more satellites can be added to expand the service area or support more elaborate missions.
“Moonlight will provide a remarkable paradigm shift in exploration,” says Javier Ventura-Traveset, who is ESA’s Moonlight Navigation Manager. “Instead of each lunar mission requiring its own complex communication and navigation systems with heavy reliance on support from Earth, Moonlight will enable future missions to access broadband communication services and GNSS-like navigation systems directly from lunar orbit, all under a service agreement with a commercial provider.”
It is unclear to what extent China or other countries could collaborate on existing lunar navigation constellation systems, or whether the moon will have multiple versions of GNSS, as Earth does. Earlier this summer, a team of researchers from the Chinese Academy of Space Technology presented Phase plan An article on GPS-style constellations was published in the journal Chinese Space Science and Technology.
“China has expressed interest in developing lunar navigation infrastructure in several international forums and has already launched Queqiao-2, a lunar communications relay satellite, this year,” notes Ventura-Traveset. “Like ESA, NASA and JAXA, it is likely that China will also develop its own lunar navigation constellation. In some of these international forums, China has also expressed interest in pursuing international interoperability.”
The emergence of these many competing concepts has led some to wonder whether they have entered new “space race” to establish the first lunar version of GPS. But Gramling doesn’t see it that way. “All I know is that we’re keeping our heads down and working with our partners because we have missions that we need to support in the relatively near future,” he says. “We’re just trying to focus on making sure that the partners that we’re working with at LunaNet have confidence in the services that we’re trying to provide and that we’re working together.”
Patla pointed out that last month the International Astronomical Union, an umbrella organization for many astronomical issues, voted on a resolution that emphasized cooperation in establishing the time scale of the Moon and other elements of the lunar PNT systems.
“At least initially, collaboration would be cheaper and would benefit everyone,” Patla says. “But we don’t know how it will turn out.”
Update 4/09/2024 14:20 UK time: Corrected Cheryl Gramling’s job title.