Timekeeping and Time Dissemination in a Distributed Space-based Clock Ensemble

This paper examines the timekeeping environments of several orbital and aircraft flight scenarios for application to the next generation architecture of positioning, navigation, timing, and communications. The model for timekeeping and time dissemination is illustrated by clocks onboard the International Space Station, a Molniya satellite, and a geostationary satellite. A mathematical simulator has been formulated to model aircraft flight test and satellite scenarios. In addition, a time transfer simulator integrated into the Formation Flying Testbed at the NASA Goddard Space Flight Center is being developed. Real-time hardware performance parameters, environmental factors, orbital perturbations, and the effects of special and general relativity are modeled in this simulator for the testing and evaluation of timekeeping and time dissemination algorithms.