Tag: LuGRE

  • LuGRE mission: NASA and ASI release lunar experiment navigation data

    LuGRE mission: NASA and ASI release lunar experiment navigation data

    During a public workshop at the Italian Space Agency on Oct. 14-15, the Lunar GNSS Receiver Experiment (LuGRE) project team celebrated the closure of the project and released the data collected to the scientific community. 

    LuGRE, developed in partnership by NASA and the Italian Space Agency (ASI), flew to the Moon a GNSS receiver manufactured by the Italian company Qascom. The receiver was hosted aboard the Firefly BGM1 mission.

    LuGRE demonstrated that signals from GNSS satellite constellations can also be used for positioning, navigation and timing (PNT) on the Moon.

    The Navigation Signal Analysis and Simulation of the Dept. of Electroncis and Telecommunications of Polytechnic University of Turin processed the data received during the mission and contributed to all the science team activities, including the validation of the data and the processing of the initial set of scientific results.

    The full set of data collected during the space mission, which took place between Jan. 16 and March 16, is now available.

    An artist’s concept of the LuGRE payload on Blue Ghost and its three main records in transit to the Moon, in lunar orbit and on the Moon’s surface. (Image: NASA/Dave Ryan)
    An artist’s concept of the LuGRE payload on Blue Ghost and its three main records in transit to the Moon, in lunar orbit and on the Moon’s surface. (Image: NASA/Dave Ryan)

    Launched on Firefly Aerospace’s Blue Ghost lander in January, LuGRE became the first payload to use Earth’s GNSS to calculate a navigation fix on the lunar surface and in lunar orbit. The experiment set a series of distance records on its journey to the Moon, demonstrating that GNSS technology can complement other navigation tools as far as 247,520 miles (398,350 km) from Earth.

    These results point to a future where lunar astronauts, rovers and spacecraft can rely on the same satellite-based navigation systems we use every day to augment their navigation capabilities.

    “It is a very important milestone for the satellite navigation community,” said Fabio Dovis, Politecnico di Torino, Italian Space Agency, of the project. “For the first time we have the recording of signal of the GPS and Galileo constellation collected in space and on the Moon surface. Already during the LuGRE mission we proved the feasibility of using satellite systems originally designed to be used on Earth up to lunar distances. Now the entire scientific community can use them to ‘re-play’ the space environment as well as analyze them in depth, for example, to retrieve information about the Earth atmosphere crossed by the signal themselves.”

    Artistic rendering of LuGRE and the GNSS constellations. In reality, the Earth-based GNSS constellations take up less than 10 degrees in the sky, as seen from the Moon. (Image: NASA/Dave Ryan)
    Artistic rendering of LuGRE and the GNSS constellations. In reality, the Earth-based GNSS constellations take up less than 10 degrees in the sky, as seen from the Moon. (Image: NASA/Dave Ryan)

    The data release includes the actual GPS and Galileo radio signals LuGRE captured during its journey and on the lunar surface. The raw recordings — called in-phase and quadrature (I/Q) samples — allow researchers to analyze GNSS signal strength, noise and interference under lunar conditions for the first time. Engineers and scientists will use these results to model and refine the next generation of GNSS-based signal receivers and improve our understanding of how navigation signals operate at the Moon.

    Graphic representation of the relative geometry of Earth-Moon- acquired GNSS satellites. (Photo: Agenzia Sapaziale Italiana)
    Graphic representation of the relative geometry of Earth-Moon-acquired GNSS satellites. (Image: Agenzia Sapaziale Italiana)
  • GNSS on the moon: Lunar PNT era begins

    GNSS on the moon: Lunar PNT era begins

    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.

    A SpaceX Falcon 9 rocket carrying Firefly Aerospace’s Blue Ghost Mission 1 lander prepares for a launch to the moon on Jan. 14, 2025, from Launch Complex 39A at the agency’s Kennedy Space Center in Florida. (Photo: NASA / Kim Shiflett)
    A SpaceX Falcon 9 rocket carrying Firefly Aerospace’s Blue Ghost Mission 1 lander prepares for a launch to the moon on Jan. 14, 2025, from Launch Complex 39A at the agency’s Kennedy Space Center in Florida. (Photo: NASA / Kim Shiflett)

    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.

    Firefly aerospace’s Blue Ghost Mission 1 lander is carrying 10 NASA science and technology instruments to the moon as part of NASA’s CLPS initiative and Artemis campaign. (Photo: Firefly Aerospace)
    Firefly aerospace’s Blue Ghost Mission 1 lander is carrying 10 NASA science and technology instruments to the moon as part of NASA’s CLPS initiative and Artemis campaign. (Photo: Firefly Aerospace)

    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.

    A Graphic representation of the relative geometry of Earth-moon-acquired GNSS satellites. (Photo: Agenzia Sapaziale Italiana)
    A Graphic representation of the relative geometry of Earth-moon-acquired GNSS satellites. (Photo: Agenzia Sapaziale Italiana)

    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.

  • NASA partners with Firefly Aerospace for lunar GNSS mission

    NASA partners with Firefly Aerospace for lunar GNSS mission

    As a part of the NASA Commercial Lunar Payload Services initiative, Firefly Aerospace will land the Blue Ghost lander on the lunar surface in 2024. Onboard, the Lunar GNSS Receiver Experiment (LuGRE) payload will determine whether signals from two GNSS constellations can reach the lander and provide precise navigation on the moon for future missions.

    During a 12-day mission in the moon’s Mare Crisium basin, LuGRE will obtain the first GNSS fix on the lunar surface and receive signals from both GPS and Galileo. The LuGRE payload is managed by NASA’s Space Communications and Navigation program office.

    This payload is a collaborative effort between NASA and the Italian Space Agency to expand the capabilities of Earth-based navigation systems. Navigation engineers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, have been testing the payload’s GNSS receiver and low noise amplifier. The receiver was developed and built by the Italian company Qascom.

    These components will be critical to LuGRE obtaining signals from the GPS and Galileo satellites. To prepare for operating on the moon, NASA engineers used a GNSS simulator to test and configure the payload to accurately receive and process the signals.

    The LuGRE payload GNSS receiver and low noise amplifier. (Image: NASA/Dave Ryan)
    The LuGRE payload GNSS receiver and low noise amplifier. (Image: NASA/Dave Ryan)

    The Goddard team delivered in February the flight hardware to Firefly Aerospace in Cedar Park, Texas, where it will be integrated into the Blue Ghost lander.

    Astronauts and rovers traversing the lunar surface will need precise location and tracking data for their exploration endeavors. The data gathered from the LuGRE payload will be used to further develop GNSS-based navigation systems for future missions to the moon.

    Image: NASA
    Image: NASA

  • NASA moon mission set to break record in navigation signal test

    NASA moon mission set to break record in navigation signal test

    Collaboration powers GPS and Galileo navigation experiment

    By Danny Baird
    ​NASA’s Goddard Space Flight Center

    As the Artemis missions journey to the Moon and NASA plans for the long voyage to Mars, new navigation capabilities will be key to science, discovery and human exploration.

    Through NASA’s Commercial Lunar Payload Services initiative, Firefly Aerospace of Cedar Park, Texas, will deliver an experimental payload to the Moon’s Mare Crisium basin. NASA’s Lunar GNSS Receiver Experiment (LuGRE) payload will test a powerful new lunar navigation capability using Earth’s GNSS signals at the Moon for the first time.

    “In this case, we are pushing the envelope of what GNSS was intended to do — that is, expanding the reach of systems built to provide services to terrestrial, aviation, and maritime users to also include the fast growing space sector,” said J.J. Miller, deputy director of Policy and Strategic Communications for NASA’s Space Communications and Navigation (SCaN) program. “This will vastly improve the precision and resilience of what was available during the Apollo missions, and allow for more flexible equipage and operational scenarios.”

    LuGRE — developed in partnership with the Italian Space Agency (ASI) – will receive signals from both GPS and Galileo, and use them to calculate the first-ever GNSS location fixes in transit to the Moon and on the lunar surface.

    “Space missions close to Earth have long relied on GNSS for their navigation and timekeeping,” said Joel Parker, LuGRE principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “In recent years, NASA and the international community have pushed the boundaries of what was considered possible by using these techniques in the Space Service Volume and beyond.”

    This graphic details the different areas of GNSS coverage. (Image: NASA/Danny Baird)
    This graphic details the different areas of GNSS coverage. (Image: NASA/Danny Baird)

    Missions in the GNSS Space Service Volume — from about 1,800 miles to 22,000 miles in altitude — receive signals that spill past Earth’s edge from GNSS satellites on the opposite side of the planet. The first Space Service Volume experiments occurred around the dawn of the new millennium. Since then, numerous missions in the Space Service Volume have reliably used GNSS to navigate.

    In 2016, the NASA’s Magnetospheric Multiscale Mission (MMS) employed GPS operationally at a record-breaking 43,500 miles from Earth. Then, in 2019, MMS broke its own record by fixing its location with GPS at 116,300 miles from Earth — nearly halfway to the Moon.

    At these extreme altitudes, missions need extremely sensitive GNSS receivers. The LuGRE mission will use a specialized weak-signal receiver developed by Qascom, an Italian company specializing in space cybersecurity and satellite navigation security solutions, and funded by ASI.

    LuGRE teams are now testing the payload in preparation to deliver it for integration onto the Firefly “Blue Ghost” lander in November of this year. Launch is slated for no earlier than 2024 from Cape Canaveral, Florida, aboard a SpaceX Falcon 9 rocket.

    During the multi-week flight to the Moon, LuGRE will collect GNSS signals and perform navigation experiments at different altitudes and in lunar orbit. After landing, LuGRE will deploy its antenna and begin 12 days of data collection, with the potential for extended mission operations. NASA and ASI will process and analyze data downlinked to Earth, and then share results publicly.

    “LuGRE is the latest effort in a long line of missions designed to expand high-altitude GNSS capabilities,” said Fabio Dovis, LuGRE co-principal investigator, ASI. “We’ve developed a cutting-edge experiment that will serve as the foundation for operational GNSS systems at the Moon.”

    The LuGRE mission seeks to spark further development of GNSS-based navigation capabilities near and on the Moon, even as NASA plans to begin using high-altitude GNSS operationally for future lunar missions. NASA and ASI will bring the results of this work forward to the space community through the International Committee on GNSS, a United Nations forum focused on ensuring the interoperability of GNSS signals. These capabilities are also a key stepping stone towards building LunaNet, an architecture that will unify cooperative networks into seamless lunar communications and navigation services.

    Artistic rendering of LuGRE and the GNSS constellations. In reality, the Earth-based GNSS constellations take up less than 10 degrees in the sky, as seen from the Moon. (Image: NASA/Dave Ryan)
    Artistic rendering of LuGRE and the GNSS constellations. In reality, the Earth-based GNSS constellations take up less than 10 degrees in the sky, as seen from the Moon. (Image: NASA/Dave Ryan)

    “The lunar deliveries we’re sourcing from commercial vendors are providing a number of innovative new technologies and opportunities to conduct experiments with affordable access to the lunar surface,” said Jay Jenkins, Commercial Lunar Payload Services Program executive. “LuGRE is one example of the progress that government and industry can make when united in their exploration objectives.”

    Developing new uses of GNSS for emerging space operations is a priority for the SCaN program at NASA headquarters, as the lead organization responsible for implementing guidance from Space Policy Directive-7, which directs NASA to develop requirements for GPS support of space operations and science in higher orbits and beyond into cislunar space.

  • NASA analyzes navigation needs of Artemis Moon missions

    NASA analyzes navigation needs of Artemis Moon missions

    Space communications and navigation engineers at NASA are evaluating the navigation needs for the Artemis program, including identifying the precision navigation capabilities needed to establish the first sustained presence on the lunar surface.

    “Artemis engages us to apply creative navigation solutions, choosing the right combination of capabilities for each mission,” said Cheryl Gramling, associate chief for technology in the Mission Engineering and Systems Analysis Division at Goddard Space Flight Center in Greenbelt, Maryland. “NASA has a multitude of navigation tools at its disposal, and Goddard has a half-century of experience navigating space exploration missions in lunar orbit.”

    Alongside proven navigation capabilities, NASA will use innovative navigation technologies during the upcoming Artemis missions.

    “Lunar missions provide the opportunity to test and refine novel space navigation techniques,” said Ben Ashman, a navigation engineer at Goddard. “The Moon is a fascinating place to explore and can serve as a proving ground that expands our navigation toolkit for more distant destinations like Mars.”

    Illustration of NASA's lunar-orbiting Gateway and a human landing system in orbit around the Moon. (Image: NASA)
    Illustration of NASA’s lunar-orbiting Gateway and a human landing system in orbit around the Moon. (Image: NASA)

    Ultimately, exploration missions need a robust combination of capabilities to provide the availability, resiliency, and integrity required from an in-situ navigation system. Some of the navigation techniques being analyzed for Artemis include the following.

    Radiometrics, optimetrics and laser altimetry

    Radiometrics, optimetrics, and laser altimetry measure distances and velocity using the properties of electromagnetic transmissions. Engineers measure the time it takes for a transmission to reach a spacecraft and divide by the transmission’s rate of travel — the speed of light.

    These accurate measurements have been the foundation of space navigation since the launch of the first satellite, giving an accurate and reliable measurement of the distance between the transmitter and spacecraft’s receiver. Simultaneously, the rate of change in the spacecraft’s velocity between the transmitter and spacecraft can be observed due to the Doppler effect.

    Radiometrics and optimetrics measure the distances and velocity between a spacecraft and ground antennas or other spacecraft using their radio links and infrared optical communications links, respectively. In laser altimetry and space laser ranging, a spacecraft or ground telescope reflects lasers off the surface of a celestial body or a specially designated reflector to judge distances.

    The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) sends laser pulses down to the surface of the Moon from the orbiting spacecraft. These pulses bounce off of the Moon and return to LRO, providing scientists with measurements of the distance from the spacecraft to the lunar surface. As LRO orbits the Moon, LOLA measures the shape of the lunar surface, which includes information about the Moon's surface elevations and slopes. This image shows the slopes found near the South Pole of the Moon. (Image: NASA/LRO)
    The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) sends laser pulses down to the surface of the Moon from the orbiting spacecraft. These pulses bounce off of the Moon and return to LRO, providing scientists with measurements of the distance from the spacecraft to the lunar surface. As LRO orbits the Moon, LOLA measures the shape of the lunar surface, which includes information about the Moon’s surface elevations and slopes. This image shows the slopes found near the South Pole of the Moon. (Image: NASA/LRO)

    Optical navigation

    Optical navigation techniques rely on images from cameras on a spacecraft. There are three main branches of optical navigation.

    • Star-based optical navigation uses bright celestial objects such as stars, moons, and planets for navigation. Instruments use these objects to determine a spacecrafts’ orientation and can define their distance from the objects using the angles between them.
    • As a spacecraft approaches a celestial body, the object begins to fill the field of view of the camera. Navigation engineers then derive a spacecraft’s distance from the body using its limb — the apparent edge of the body — and centroid, or geometric center.
    • At a spacecraft’s closest approach, Terrain Relative Navigation uses camera images and computer processing to identify known surface features and calculate a spacecraft’s course based on the location of those features in reference models or images.

    NASA will use data gathered from LuGRE to refine operational lunar GNSS systems for future missions.


    Weak-signal GPS and GNSS

    NASA is developing capabilities that will allow missions at the Moon to leverage signals from GNSS constellations. These signals — already used on many Earth-orbiting spacecraft — will improve timing, enhance positioning accuracy, and assist autonomous navigation systems in cislunar and lunar space.

    In 2023, the Lunar GNSS Receiver Experiment (LuGRE), developed in partnership with the Italian Space Agency, will demonstrate and refine this capability on the Moon’s Mare Crisium basin. LuGRE will fly on a Commercial Lunar Payload Services mission delivered by Firefly Aerospace of Cedar Park, Texas. NASA will use data gathered from LuGRE to refine operational lunar GNSS systems for future missions.

    Illustration of Firefly Aerospace’s Blue Ghost lander on the lunar surface. The lander will carry a suite of 10 science investigations and technology demonstrations to the Moon in 2023 as part of NASA's Commercial Lunar Payload Services (CLPS) initiative. (Image: Firefly Aerospace)
    Illustration of Firefly Aerospace’s Blue Ghost lander on the lunar surface. The lander will carry a suite of 10 science investigations and technology demonstrations to the Moon in 2023 as part of NASA’s Commercial Lunar Payload Services (CLPS) initiative.

    Autonomous navigation

    Autonomous navigation software leverages measurements like radiometrics, celestial navigation, altimetry, terrain-relative navigation, and GNSS to perform navigation onboard without contact with operators or assets on Earth, enabling spacecraft to maneuver independently of terrestrial mission controllers. This level of autonomy enables responsiveness to the dynamic space environment.

    Autonomous navigation can be particularly useful for deep space exploration, where the communications delay can hamper in-situ navigation. For example, missions at Mars must wait eight to 48 minutes for round trip communications with Earth depending on orbital dynamics. During critical maneuvers, spacecraft need the immediate decision-making that autonomous software can provide.

    LunaNet navigation services

    LunaNet is a unique communications and navigation architecture developed by NASA’s Space Communications and Navigation (SCaN) program. LunaNet’s common standards, protocols, and interface requirements will extend internetworking to the Moon, offering unprecedented flexibility and access to data.

    For navigation, the LunaNet approach offers operational independence and increased precision by combining many of the methods above into a seamless architecture. LunaNet will provide missions with access to key measurements for precision navigation in lunar space.

    Artist's conceptualization of Artemis astronauts using LunaNet services on the Moon. a unique approach to lunar communications and navigation. The LunaNet communications and navigation architecture will enable the precision navigation required for crewed missions to the Moon and place our astronauts closer to scientifically significant lunar sites, enhancing the our missions’ scientific output. (Image: NASA/Resse Patillo)
    Artist’s conceptualization of Artemis astronauts using LunaNet services on the Moon, a unique approach to lunar communications and navigation. The LunaNet communications and navigation architecture will enable the precision navigation required for crewed missions to the Moon and place our astronauts closer to scientifically significant lunar sites, enhancing the our missions’ scientific output. (Image: NASA/Resse Patillo)