The United States and China are locked in a new race, in space and on Earth, over a fundamental resource: time itself. And the United States is losing. Global positioning satellites serve as clocks in the sky, and their signals have become fundamental to the global economy — as essential for telecommunications, 911 services and financial exchanges as they are for drivers and lost pedestrians. But those services are increasingly vulnerable as space is rapidly militarized and satellite signals are attacked on Earth. Yet, unlike China, the United States does…