T2L2 on Jason-2: First Evaluation of the Flying Model

Ph. Guillemot, I. Petitbon, E. Samain, P. Vrancken, J. Weick, D. Albanese, F. Para, J.-M. Torre

Abstract:	The new generation of optical time transfer (T2L2: Time Transfer by Laser Link [1]) under development at OCA and CNES shall allow the synchronization of remote ultra-stable clocks and the determination of their performances over intercontinental distances. The principle is based on the propagation of light pulses between clocks for synchronization. T2L2 is the follow-on mission to LASSO [2] (Laser Synchronization from Stationary Orbit) with performances improved by two orders of magnitude. A T2L2 payload shall be launched in mid 2008, together with the Jason-2 space vehicle dedicated to the observation of the oceans. A preliminary performance budget and a ground experiment conducted by the OCA permit to envision a performance improvement of at least one order of magnitude as compared to the best time transfer techniques available. Expected performances are in the 100 ps range for accuracy, with an ultimate stability better than 1 ps over 1000 s (one pass) and than 10 ps over 1 day. Time transfer performances in a common view mode are driven by the noise of both the ground and the onboard timers, whereas the performances in a non-common view configuration are limited by the onboard clock (DORIS USO). The main objectives of the T2L2 mission are technological (In-orbit functional and performance validation), scientific (Time & Frequency metrology and Fundamental physics tests), and a contribution to the Jason-2 core mission (Evaluation of the behaviors, versus radiations, of the DORIS USO). A first breadboards of the electronics have been developed and measurements conducted by the OCA are very promising [3]. Since then, both an engineering and a flight model have been developed. By the time of the conference, the flying model of T2L2 instrument shall be delivered to CNES and performance characterization shall be running. After a quick reminder of mission hypothesis and objectives, with associated preliminary link budget and expected performances, this paper will present last results obtained on both a T2L2 engineering model and a flying model.
Published in:	Proceedings of the 38th Annual Precise Time and Time Interval Systems and Applications Meeting December 7 - 9, 2006 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	329 - 336
Cite this article:	Guillemot, Ph., Petitbon, I., Samain, E., Vrancken, P., Weick, J., Albanese, D., Para, F., Torre, J.-M., "T2L2 on Jason-2: First Evaluation of the Flying Model," Proceedings of the 38th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, December 2006, pp. 329-336.
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