“I call LunaNet a big umbrella,” Gramling says, “It’s an architecture that defines the standards that will be used for interoperable communications, location, navigation and timing services. There is a large effort underway to define these standards and document them in the LunaNet Interoperability Specification.”
“This is a completely different paradigm than on Earth, where the U.S. has GPS, Europe has Galileo and Russia has GLONASS,” she adds. “It’s still early days, so the idea is to work together as the three partners that have been involved with LunaNet so far and establish one system between the three.”
In other words, NASA, ESA, and JAXA are each working on separate projects for now, but will eventually merge their ideas into a single operating system. The detailed plans for ESA’s Moonlight initiative help us imagine what a lunar GNSS constellation might eventually look like.
As currently envisioned by ESA, Moonlight would consist of at least five satellites, including one large communications satellite and four smaller, dedicated navigation satellites placed in special orbits to optimize coverage of the lunar south pole. This initial configuration would provide 15 hours of reliable and predictable PNT service every 24 hours in the coverage area, but Moonlight is also designed with scalability in mind, allowing for additional satellites to be added to expand the service area or support more complex missions.
“Moonlight will bring about an incredible paradigm shift in the field of exploration,” says Javier Ventura-Traveset, Moonlight Navigation Manager at ESA. “Until now, lunar exploration missions have required their own complex communications and navigation systems that are heavily reliant on Earth-based support, but thanks to Moonlight, future missions will be able to access broadband communications services and GNSS-like navigation systems directly from lunar orbit, based on service agreements with commercial providers.”
It’s unclear to what extent China and other countries will cooperate on existing lunar navigation satellite constellations, or whether the Moon will end up with multiple versions of GNSS, as it has on Earth. Earlier this summer, a team of scientists from the China Academy of Space Science and Technology published a paper in the China Space Science and Technology journal outlining a phased plan for a GPS-style constellation.
“China has signaled interest in developing lunar navigation infrastructure in several international forums, having already launched its lunar communications relay satellite Queqiao-2 this year,” Ventura-Travesset noted. “Like ESA, NASA, and JAXA, China will likely develop its own constellation of lunar navigation satellites. China has also signaled interest in pursuing international interoperability in some of these international forums.”
The emergence of these multiple competing concepts has led some to wonder if we’ve entered a new “space race” to establish the first lunar version of GPS. But Gramling doesn’t think so. “We’re just working diligently with our partners because we have missions that we have to support in the relatively near future,” she says. “We’re just focused on making sure that the services we’re trying to provide are robust among the partners that we’re working with on LunaNet, and that we’re working collaboratively.”
Patra noted that last month, the International Astronomical Union, an organization that mediates on a range of astronomy issues, voted for a resolution emphasizing cooperation to establish a lunar time scale and other elements of a lunar PNT system.
“Collaboration will likely keep costs down and benefit everyone, at least in the early stages,” Patra said, “but it remains to be seen how this will play out.”
Updated 4 September 2024 at 14:20pm BST: Cheryl Gramling’s job title has been corrected.
