03/2014: On March 25th, 2014, the T2L2 - ELT workshop gathered in Wettzell representatives of the T2L2 (Time Transfer by Laser Link) and ELT (European Laser Timing) project as well as some European laser stations around the status and the future of the laser links for the metrology of time and of frequency.
This workshop was the opportunity to review the last results of T2L2, the progress of ELT and the perspectives of collaboration around these 2 projects.
- Ph. Guillemot : T2L2, mission status and results
- M. Laas-Bourez : T2L2 Calibration Campaign
- C. Courde : T2L2 station collocation at OCA
- U. Schreiber : ELT Concept, Overview and Prospective
- I. Prochazka : ELT Space Segment and Calibration
- A. Schlicht : ELT Data-Center
- J. Kodet : ELT Station requirements
- J. Eckl : Detector Bias reduction
- U. Schreiber : ELT Laser Safety
- U. Schreiber : Timing Systems - Going Optical
09/2013: After the campaigns in 2009 and 2010, the transportable Laser station is back on the roof of Paris Observatory for a new measurement campaign.
This campaign involves some of the best European Laser stations, Herstmonceux in England, Wettzell in Germany and Grasse in France. The objective is to reach a measurement precision of a few picoseconds and to compare T2L2 with other techniques, radio-frequency ones, of time transfer with an uncertainty around a nanosecond.
06/2013: Jason-2 and T2L2 celebrated their 5 years of operations.
Jason-2 mission is at the end of its nominal exploitation period, The 4 partners of the project, CNES, NASA, EUMETSAT and NOAA decided to extend the program by 5 additional years.
12/2012: T2L2 instrument has just detected its 100 millionth optical event.
Practically, only about half these events correspond to real laser echoes. The other half is due to the noise generated by the light of the Sun reflected by the Earth.
06/2012: After the Mission Extension Review, T2L2 instrument operations are extended until the end of 2014.
The Scientific data exploitation will extend until the end of 2015. These 2 additional years should allow the inter-comparison between the five best European Laser stations, inter-comparisons at inter-continental scales and first tests of fundamental Physics.
02/2012: After Wettzell station in Germany in June 2011, it is Herstmonceux station in Great Britain that is calibrated.
This calibration should ensurer the exactness of the time transfer at better than 100 ps.
10/2011: End of the measurement campaign with the transportable laser station in Tahiti.
90 laser passes have been realized, of which 60 in common with the MeO station in Grasse.
06/2011: 3 years of in orbit operation, contract fulfilled for T2L2 instrument.
Since the launch and with an availability rate over 98%, a little more than 250 millions events have been dated by the instrument, of which 10 to 15% of real laser shootings.
05/2011: Kick-off of a measurement campaign from Tahiti with the transportable laser station
The FTLRS laser station and a hydrogen maser have been set up at the Polynesia University site.
04/2011: First multi-technique comparison results on Paris and Grasse link
T2L2 data have been compared with GPS time transfer data and TWSTF technique (Two Way Satellite Time and Frequency Transfer).
01/2011: T2L2 and Jason-2 mission available on 3D View Multimission.
This web tool accessible to the public, enables the visualization, from orbite and attitude data, the position of Jason-2 satellite as well as the instruments' field of view. Several missions are also available.
10/2010: End of the 2010 international campaign
The transportable laser station enabled to realize 135 laser passages on Jason-2, of which 83 in common view with the fixed laser station of the Côte d'Azur Observatory.
05/2010: Kick off of the 2010 international campaign
This campaign will involve 8 laser stations (Herstmonceux (GBR), Paris (FRA), Zimmerwald (CHE), Grasse (FRA), Koganei (JPN), Matera (ITA), Simosato (JPN), Wettzell (DEU)) of which the FTLRS transportable laser station which is back at Paris Observatory for the summer.
04/2010: At the end of the Mission Extension Review process, the T2L2 mission exploitation is extented to the end of 2012.
An excellent news when T2L2 instrument is on the verge of celebrating its second in orbit anniversary.
09/2009: First campaign with the transportable laser station installed at Paris Observatory.
This campaign should enable to validate the laser operations from the Observatory site before an international measurements campaign in 2010.
06/26/2009: T2L2, one year and more than 8 millions of laser echoes.
Already one year that T2L2 instrument, dedicated to high precision time transfer, was turned on on June 25, 2008 on board Jason-2 satellite. One year and not a wrinkle. All technological parameters are nominals and the instrument recorded more than 8 millions of laser echoes. The exploitation of these first data has already enable to demonstrate unparalleled time transfer performances by radioscience systems, with residual noises of a few dozen of picosecond on observation times of a few dozen seconds.
01/08/2009: After a little over 6 months of operation and a successful in-flight commissioning, T2L2 offically enters the exploitation phase.
06/29/2008: Detection of the first laser echoes - the instrument function very satisfactorily.
First laser echoes recorded by T2L2: the first station detected is Yarragadee station in Australia (Red and Green: Power of the laser echoes, the lower values correspond to the noise generated by reflection of the Sun on the Earth; Blue: Measure of the reflection of the Sun on the Earth, night (higher values) - day (lower values, period when the instrument record the most noises) alternation can clearly be seen.