[goatinaboat]

How many people on the boat do you need that know celestial navigation?

Easy. The same number that know how to use a GPS. Your one guy may be the first casualty.

We've got plenty of ways to defeat jamming, the newest block of GPS satellites have ways to increase signal power in certain areas and anti-radiation missiles can blow up a jammer.

What do you do when your enemy dumps a load of sand in orbit?

[ls612]

GPS isn’t in low earth orbit it’s in a very high orbit so it shouldn’t be vulnerable to either asat missiles or space junk clogging up its orbit