GPS on the Moon? NASA’s working on it

If you’re driving your car from Portland to Merced, you probably rely on GPS to see where you are. But what if you’re driving your Moon rover from Oceanus Procellarum to the Sea of Tranquility? Actually, GPS should be fine — if this NASA research pans out.
Knowing exactly where you are in space, relative to other bodies anyway, is definitely a non-trivial problem. Fortunately the stars are fixed and by triangulating with them and other known landmarks, a spacecraft can figure o