Nations ready to deny U.S. of navsat dominance
While it may be hard to believe that the global positioning system (GPS) is already more than a quarter century old, it may be equally difficult to imagine

While it may be hard to believe that the global positioning system (GPS) is already more than a quarter century old, it may be equally difficult to imagine that by 2020 there will be more than 100 navigation satellites crisscrossing in outer space, high above us. Yet the first is true and, barring unforeseen eventualities, the second will also be true.