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 out its location quite precisely.
But that’s so much work! Here on Earth we gave that up years ago, and now rely (perhaps too much) on GPS to tell us where we are to within a few meters.
By creating our own fixed stars — satellites in geosynchronous orbits — constantly emitting known signals, we made it possible for our devices to quickly sample those signals and immediately locate themselves.
That sure would be handy on the Moon, but a quarter of a million miles makes a lot of difference to a system that relies on ultra-precise timing and signal measurement. Yet there’s nothing theoretically barring GPS signals fr ..
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