Historically, navigation systems have depended on time. This was clearly demonstrated by the sailing of Harrison’s chronometer on HMS Deptford in 1761, to prove that the instrument allowed navigators for the first time to determine longitude accurately and reliably. Because of this relationship between navigation and time, the timekeeping community has always had a keen interest in the use of navigation systems for the distribution of time. Even today, the heart of the GPS rests on a highly evolved clock technology. Unlike navigators, who need four GPS satellites by which to determine their position, timekeepers who know their position need only one satellite to determine time. Observations of a single satellite could allow timekeepers to remotely synchronize clocks around the world.