Atomic Clocks for Space Applications

F. Emma, G. Busca, P. Roehat

Abstract:	The overall performance of navigation payloads is dependent on the performance of the on-board clocks. Better long-term stability leads directly to improved space segment autonomy and simplified ground segment operation. The European Space Agency supports the development of advanced atomic clocks in the frame of its Technology Demonstration Program and more recently under the GNSS-2 program. Two major activities are currently running the aim of which is to fully space qualify a Rubidium Atomic Frequency Standard (RAFS) and a Space Hydrogen Maser (SHM). The development activity for the Rubidium clocks is driven by the following major goal specifications: • Mass < 1 Kg • Short term Stability (100s) < 5x10 -13, flicker floor _< 5xlO "14 • Volume < 0.85 L Special emphasis has been placed on reliability for a 10- year mission. The development activity for the Space Hydrogen Maser will result in the manufacture and test of two Masers for two different missions. The ACES mission flying on the International Space Station will provide an opportunity for an early demonstration of the Space Maser. Navigation missions will use the Maser as high stability, primary frequency source. The Maser activity will lead to a compact, low weight (35 Kg) clock, capable of a frequency stability of lxl0 15 over averaging intervals of 1'000 to 10'000s. This article presents an overview of the activities and provides information on the technological challenges of the two development programs.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	2285 - 2292
Cite this article:	Emma, F., Busca, G., Roehat, P., "Atomic Clocks for Space Applications," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 2285-2292.
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