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Historical context of GNSS in space

The latest historic chapter in GNSS for space users was launched, as one would expect, at an Institute of Navigation (ION) GNSS+ conference — the one in Miami in 2019 — by a handful of technical and policy experts well positioned to “Go for the Gold” — GNSS on the moon! Thus, liquid refreshments in hand, the Lunar GNSS Receiver Experiment (LuGRE) concept was born, amongst excited discussion and scribbling on napkins by Oscar Pozzobon (Qascom), Joel Parker (NASA), Frank Bauer (NASA), Alberto Tuozzi (Agenzia Spaziale Italiana or ASI, Italian Space Agency), Lisa Valencia (NASA) and James “JJ” Miller (NASA).

Long before this productive, informal brainstorming session, global navigation satellite systems (GNSS), such as the U.S. GPS, were originally designed for use on or near Earth, providing positioning, navigation and timing (PNT) services up to an altitude of about 3,000 km (the GPS Terrestrial Service Volume). Over the decades, experimental missions pushed GNSS use higher, and by 2006, GPS specifications defined a Space Service Volume, extending GNSS services out to 36,000 km (geosynchronous orbit). NASA missions then deftly demonstrated GNSS utility well beyond Earth orbit — notably in 2019 with the Magnetospheric Multiscale Mission spacecraft formation, which successfully tracked GPS signals roughly 192,500 km from Earth, setting the world record for farthest and fastest reception of any GNSS signals in the space domain.

Building on this success, NASA proposed conducting the LuGRE in 2020 by using a combination of GPS and Europe’s Galileo signals at lunar distances. The flight opportunity for a lunar mission came through NASA’s new Commercial Lunar Payload Services (CLPS) initiative, and by early 2021, Firefly Aerospace was awarded the mission to carry LuGRE to the moon. The LuGRE team was very fortunate from the start, competing for and winning the last of 10 payload slots, and the only space operations flight demonstration amongst nine other science payloads focused more on assessing the lunar environment.

The progress of this initiative reflects a broader national and international push based on NASA’s role in implementing the 2021 U.S. Space Policy Directive-7, which directs NASA to work with the U.S. Space Force and other partners to extend GNSS capabilities farther into cislunar space to benefit both government and commercial users. Internationally, GNSS providers further cooperate through the UN-sponsored International Committee on GNSS to develop interoperable PNT standards for space users beyond Earth. So, ASI was a natural fit to become NASA’s international partner. The Italian GNSS company Qascom was awarded the receiver development, while the Polytechnic of Turin provided academic support. This historic groundwork has thus set the stage for the recent LuGRE mission to achieve several accomplishments in lunar navigation, breaking three world records in the process.

Mission overview: Blue Ghost Lander and CLPS

The LuGRE payload traveled to the moon aboard Blue Ghost Mission 1, a robotic lunar lander built by Firefly Aerospace under NASA’s CLPS program. CLPS, started in 2018, is a public-private partnership model through which NASA contracts commercial landers to deliver science and technology payloads to the lunar surface. Blue Ghost Mission 1 launched on Jan. 15, 2025, via a SpaceX Falcon 9 rocket and touched down on March 2, 2025. This made Firefly the first U.S. commercial company to successfully land on the moon upright, delivering 10 NASA-sponsored payloads, including LuGRE. The lander targeted a site near Mons Latreille in Mare Crisium, achieving a precision landing within ~100 m of the aim point. Built as a solar-powered lander about 2 m tall and 3.5 m wide, Blue Ghost was designed for a mission duration of one lunar day (~14 Earth days). By leveraging CLPS, NASA rapidly deployed LuGRE and other instruments, demonstrating the effectiveness of commercial partnerships in advancing lunar exploration. Blue Ghost’s successful landing and operations validated this approach and set the stage for upcoming CLPS missions in support of Artemis.

The LuGRE payload: Objectives and components

LuGRE is a technology demonstration aimed at determining whether Earth-originated GNSS signals can be reliably received and used for navigation at the moon’s distance. The payload was jointly developed by NASA and ASI with engineering by Qascom. Hardware on LuGRE includes a specialized weak-signal GNSS receiver, a high-gain L-band patch antenna array with RF filtering and a low-noise amplifier. This design allows it to track faint GPS and Galileo signals nearly 400,000 km from their transmitters. LuGRE specifically listens on multiple frequencies — GPS L1 and L5, and Galileo E1 and E5a — to maximize signal acquisition opportunities. The experiment’s objectives are threefold: (1) acquire and characterize GNSS signals in lunar orbit and on the surface, (2) demonstrate navigation fixes (position/time) using those signals at the moon, and (3) return data to inform the development of future lunar-specific GNSS receivers. All three of LuGRE’s objectives were met. During the mission, LuGRE began collecting and processing data en route to the moon (during a ~45-day transit) and also on the lunar surface after landing. As one of the first demonstrations of GNSS use on another world, LuGRE set out to prove that combined GPS/Galileo signals could enable autonomous navigation for spacecraft far beyond Earth.

Benefits of GNSS for lunar PNT

If proven reliable, GNSS-based navigation at the moon offers significant benefits for future lunar missions. First, it provides a common PNT framework for lunar explorers, akin to GPS on Earth, enabling precise real-time positioning and time synchronization for astronauts and robotic systems. This could allow lunar crews and rovers to navigate autonomously across the surface without constant ground support, reducing astronaut workload and dependence on Earth-based tracking. Accurate GNSS-derived position data improves safety and efficiency — for example, helping rovers avoid hazards and chart optimal routes or aiding astronauts in pinpointing resources, such as water, ice or scientific targets. Using existing GNSS signals also means that missions might rely less on cumbersome radio tracking from Earth or lunar beacons, simplifying mission operations.

In the long run, GNSS technology can support the development of lunar infrastructure: future base camps, power stations and landing pads could all reference a shared navigation grid, much as terrestrial infrastructure does. Additionally, leveraging well-known GPS/Galileo signals could reduce costs and technical risks, supplementing a proposed new lunar navigation satellite network.

LuGRE’s results have affirmed these possibilities. During transit, LuGRE broke records by tracking signals at 395,900 km out in lunar orbit, proving multi-constellation GNSS can aid navigation to and around the moon. Shortly after landing, it further demonstrated an autonomous GNSS navigation fix on the lunar surface, 362,100 km from Earth. These achievements suggest that even existing Earth-centric satnav can be extended to serve lunar exploration, a promising development for upcoming Artemis endeavors.

Challenges of GNSS reception on the moon

Adapting GNSS to the lunar environment is challenging. The main difficulty is the weakness of signals by the time they reach the moon. GNSS satellites orbit around 20,000 km from Earth, beaming most of their signal power toward Earth’s surface. At nearly 10 times that distance, only the spillover (side-lobe) signals reach the moon, arriving attenuated and sparse. This necessitates high-sensitivity receivers and high-gain antennas (such as LuGRE’s) to even detect the signals, along with sophisticated algorithms to pull meaningful data from the noise. The geometry and coverage also pose issues: a receiver on the moon will often see a limited number of GNSS satellites above its horizon, potentially affecting the accuracy and availability of navigation fixes. Local lunar conditions add further complications. The moon’s lack of atmosphere means no ionospheric delay, which is a positive for signal clarity. However, it also means that there is nothing to refract or scatter signals over the horizon — thus, terrain plays a crucial role. Rugged topography (mountains, crater rims) can block line-of-sight to GNSS satellites, and deep craters or polar shadowed regions might have very poor reception.

The pervasive lunar dust (regolith) can also be problematic because it may coat antenna surfaces or contribute electromagnetic noise, especially during landings or surface activities. These factors require advanced processing techniques and possibly integrating GNSS with other sensors to achieve reliable navigation. LuGRE’s design and operations were tailored to confront these challenges. For instance, using dual constellations doubles the pool of satellites and signals available, and collecting data both in orbit and on the surface helps characterize how signal quality changes in different lunar conditions. The knowledge gained will guide the development of next-generation lunar GNSS receivers with improved robustness against weak signals and intermittent coverage.

Implications for Artemis and deep space navigation

LuGRE’s success is a proof of concept that navigation aids from Earth can directly support moon missions. This is of immediate relevance to NASA’s Artemis program, which aims to return humans to the moon and establish a sustained presence there. Artemis crewed vehicles (such as the Orion spacecraft) and the planned Gateway lunar station could potentially use GNSS signals during transit or in lunar orbit to autonomously determine their trajectories. On the surface, future Artemis astronauts and rovers could carry GNSS-enabled devices to know their precise location without relying solely on Earth-based tracking. This capability will become increasingly important as activities expand — from pinpoint landing of resupply craft, to coordinating lunar base operations to enabling the first long-distance treks by crew or robots on the moon.

By proving GPS/Galileo usability at the moon, LuGRE also paves the way for establishing a standardized lunar reference frame tied to existing GNSS, which all international partners can use for joint operations. In a broader sense, LuGRE is a stepping-stone toward more advanced navigation systems in deep space. It demonstrates techniques (such as combining multiple GNSS constellations and using high-sensitivity receivers) that could inform navigation around Mars or other distant targets. While Earth’s GNSS signals won’t reach Mars with useful strength, the lessons learned can drive the design of Mars-orbiting navigation satellites or better onboard autonomous nav systems for deep-space probes. In essence, the experiment is accelerating the development of a GPS-like interplanetary navigation capability, crucial for humanity’s expansion deeper into the solar system.

Policy and international collaboration

The LuGRE mission exemplifies how international and commercial partnerships are shaping the future of space exploration. It was born out of a long-running collaboration between NASA’s Space Communications and Navigation program and ASI, reflecting a shared strategic interest in extending GNSS interoperability to the moon and beyond. The receiver hardware was developed by Qascom with academic support from Politecnico di Torino, underlining the role of industry and academia in innovation.

This NASA-ASI partnership built on earlier joint projects, such as GNSS receiver experiments on the ISS and suborbital flights, which tested using both GPS and Galileo for space navigation. Europe’s Galileo system, in particular, is a full partner in LuGRE. Its inclusion alongside GPS ensures that the experiment benefits from multi-constellation redundancy and also sends a message of GNSS interoperability, a key principle endorsed by the International Committee on GNSS. On the policy front, the mission aligns with U.S. space policy goals to develop services in cislunar space and encourages momentum in international standardization of lunar PNT frameworks.

Data from LuGRE will be made public, contributing to global research and possibly the drafting of new standards for lunar navigation that any nation’s spacecraft can adopt. The CLPS program itself, which enabled LuGRE’s delivery, represents a policy shift toward commercial sourcing of lunar services — fostering a market where companies such as Firefly, intuitive Machines, Astrobotic and others compete and cooperate to advance lunar science. As NASA leads the Artemis coalition with agencies from Europe, Asia and beyond, the LuGRE experiment offers a tangible product of cooperation: a foundation for shared navigation infrastructure at the moon. This collaborative, forward-looking approach will be critical as humanity returns to the moon not just to visit, but to stay.

Conclusion

LuGRE on Firefly’s Blue Ghost lander has marked a milestone in space exploration: it demonstrated for the first time that navigational signals conceived for Earth can be harnessed on the lunar surface. By uniting cutting-edge technical work (in receivers and antennas) with visionary policy support (via NASA’s CLPS and international GNSS cooperation), LuGRE showcases a path toward robust, autonomous navigation for the Artemis generation of missions. Achieving a GPS/Galileo fix on the moon is more than a symbolic first — it is a practical step toward a future where astronauts and robots navigate the moon — and one day Mars — with the same confidence as we do on Earth. The lessons from LuGRE will inform how we guide our spacecraft across the cislunar void, how we set up the positioning networks of tomorrow’s lunar bases and how nations cooperating can build the navigation backbone for a new era of deep-space exploration. In short, LuGRE has opened the door for GNSS to become an integral part of the lunar toolkit, blending technology and policy into a giant leap for navigation beyond Earth.