Timing of Spacecraft Data: Time Accuracy Requirements and Timing Facilities of the European Space Agency (esa)

H.P. Dworak

Abstract:	The time accuracy requirements for various ESA satellite missions are analysed; the requirements are grouped by the type of mission. The evolution of satellite timing techniques since 1968 is shown, and the requirements for future ESA missions (until the late 80's) are assessed. Timing systems and their configuration at various ESA ground stations and the operations control centres are described. Based on practical experience operational aspects will be presented, covering mainly Time Synchronization, Time and Frequency corrections and typical problems encountered during routine operations such as routine monitoring, reporting, time/frequency offset calculations and adjustments. Common time reference techniques operationally used, such as VHF transmission, LORAN-C, TRANSIT and travelling Clocks are compared in terms of availability, reliability and time accuracy. The equipment performances of standard commercial timing systems, based on Caesium, Rubidium and Crystal oscillators are presented. Based on actual maintenance data acquired in ESA ground stations, the overall reliability of these systems and actual performance parameters in terms of MTBF, MDT, operational avail ability etc. are shown. Two studies on future techniques in the field of time dissemination and time synchronization conclude this paper: The LASSO mission (Laser Synchronization from Stationary Orbit) and a low-cost time dissemination technique using METEOSAT, the European meteorological satellites, are briefly outlined.
Published in:	Proceedings of the 15th Annual Precise Time and Time Interval Systems and Applications Meeting December 6 - 8, 1983 Naval Research Laboratory Washington, DC
Pages:	389 - 411
Cite this article:	Dworak, H.P., "Timing of Spacecraft Data: Time Accuracy Requirements and Timing Facilities of the European Space Agency (esa)," Proceedings of the 15th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1983, pp. 389-411.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In