Time transfer by laser link T2L2 first results

The optical time transfer project T2L2 has been successfully launched from California in 2008 on the Jason-2 satellite. T2L2 permits the synchronization at the pico-second level of remote ultra stable clocks and the determination of their performances over intercontinental distances. The principle is derived from laser telemetry technology with a space equipment designed to record arrival times of laser pulses at the satellite. Since the launch, several thousands of passes have been acquired by the laser ranging community. A first analysis permitted to validate the characteristics of the instrument such as sensitivity, noise, dynamic, and time stability. After reminding the principle, the exploitation plan, and the objectives, the paper will present the first stability obtained in the picoseconds level between an hydrogen maser at ground and an ultra stable oscillator in space.