When you’re lost on Earth, GPS is a lifeline; now, IEEE Spectrum reports, it could be on the Moon, as well. To find out whether the U.S. GPS constellation and peer satellites from Europe and Russia could help astronauts orbiting the Moon, scientists at NASA’s Jet Propulsion Laboratory calculated the trajectories of the satellites and their radio signals. They found that five to 13 of these 81 satellites would call out to lunar orbit at any one time—enough to locate a position to 200 or 300 meters, they reported at a conference this month. But on the lunar surface, especially at the poles, Earth would be low in the horizon, allowing crater rims to block these signals. A small relay satellite could bridge that gap, they say. Although GPS navigation is not yet slated for the Artemis missions, the team is trying to make sure it’s possible. “This can be done,” they say. “It’s just a matter of money.”
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