Researchers propose linking GPS satellites with lunar orbiters to offset navigation drift for Artemis missions

Researchers at the Shanghai Engineering Center for Microsatellites propose linking Earth‑based GPS satellites with spacecraft orbiting the Moon to counter navigation drift for Artemis missions, according to a sixty‑day simulation study.

Xia Lin and Baojun Lin detailed the idea in a study published in the journal Satellite Navigation, which used real‑time telemetry from twenty‑four operational BeiDou‑3 medium‑Earth‑orbit satellites. The study created synthetic cross‑links between those BeiDou‑3 MEO satellites and four spacecraft placed in Elliptical Lunar Frozen Orbits (ELFO), forming an Earth‑Moon network for a sixty‑day simulation.

To establish a baseline, the team ran a scenario with only conventional satellite‑to‑satellite links among the Earth‑orbiting vehicles and all ground‑station corrections disabled. In that Earth‑only configuration, the positioning error grew to approximately 7.85 meters by the end of the two‑month period, showing how drift accumulates without terrestrial updates. Adding a trajectory‑prediction algorithm to the Earth‑only case reduced the error to roughly 0.6 meters after sixty days, demonstrating the benefit of forward‑looking modeling.

When the Earth‑GPS constellation was networked with the four ELFO lunar orbiters, the joint Earth‑Moon system limited drift to about 0.35 meters over the same sixty‑day interval. The reciprocal link also improved lunar spacecraft positioning, leaving the four simulated ELFO orbiters with an average error of approximately 2.26 meters relative to their predicted orbits. Scientists at the National Institute of Standards and Technology have measured how the Moon’s weaker gravity affects atomic clocks on its surface.

Their findings show that lunar clocks tick faster by about 56 microseconds per day compared with identical clocks on Earth, a relativistic offset that we must correct for any lunar navigation system. To meet this challenge, NIST has developed a lunar coordinate time framework that defines a primary “Moon time” reference, analogous to UTC, to enable precise timing for a future lunar GPS‑like network.

Accurate lunar timing and positioning are essential for NASA’s Artemis program, which seeks to land astronauts within a few meters of their intended targets and to support sustained surface operations. Linking GPS satellites to lunar orbiters offers a way to keep both Earth‑based navigation and Artemis‑era lunar missions accurate even when terrestrial ground stations are unavailable.

This approach improves system robustness against outages caused by natural disasters, cyberattacks or other disruptions that can affect ground‑station networks. By providing a stable reference signal from the Moon, the joint Earth‑Moon system could support the precision needed for crewed Moon landings and future lunar infrastructure.