Time Transfert by Laser Link T2L2 On Jason 2 OCA –UMR Gemini Grasse – FRANCE Email : [email protected]E. Samain – Principal Investigator D. Albanese : Optique P. Exertier: Gemini Director M. Furia : Electronic J.F. Mangin : Laser J. Paris : Software F. Pierron: FTLRS J.M. Torre: Laser Station - ILRS P. Vrancken : Optical tests J. Weick : error - link Budget - computation CNES Toulouse – France Email : [email protected]P. Guillemot: System Engineer I. Petitbon: Project Manager
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Time Transfert by Laser Link T2L2 On Jason 2 OCA –UMR Gemini Grasse – FRANCE Email : [email protected]@obs-azur.fr E. Samain – Principal.
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» Radiation Measurements: LPT & Carmen 2» Time Transfer : T2L2
Orbit» Altitude 1336 km, i = 66°, P = 6800 s» Max distance in a common view mode : 6500
km» Time interval between pass 2h < T < 14h» 3 to 6 passes per day
T2L2 Payload T2L2 Instrument
» Event Timer» 2 optical channels: Linear – Geiger
Equipment available on Jason2» LRA : Laser Ranging Array» DORIS Ultra Stable Oscillator
T2L2 Space Instrument Synoptic
T2L2 Space Instrument
Jason 2Global View
T2L2 Field of view
From Space: +/- 55° for both T2L2 detection and LRA)
Ground StationPerformance Specifications
Event Timer:» Start Time» Return Time
Time stability requirement : below 1 ps over 1000s
Long term time stability: below 100 ps
Laser StationSpecifications
Wavelength 532 nm +/- 0.5 nm
Pulse Width: 20 to 200 ps @ FWHM
Minimum Energy per pulse : 10 mJ ; Nominal Energy: 50 mJ
Maximum rate: above 1 kHz – Nominal rate: 10 Hz
Elevation range: 5° to 90°
No time synchronisation required
Ground stationEvent timer Status
Kit T2L2
OCA Equipment
Time Transfer» TwoWay» GPS mono and multi channels
Clocks» 2 Cesium 5071A» 1 Hydrogen maser
Laser Stations » FTLRS» MeO Station (LLR)
Scientific Objectives Time and Frequency metrology
Optical Laser Link validation »
» pour > 10000 s » Uncertainty < 100 ps
Ground clock Synchronization» Compatible with the best clocks available in world
Time scale participation» BIPM/CCD recommandation
2/113y 10 4.0 )(
s 0.1 10.17 10.28 0
2½152½122x
Scientific Objectives Time transfer Inter comparison
TWSTFT et GPS calibration» Common view: amelioration : 2 order of magnitude» Possibility to work on very wide bases: synchronization via
intermediate ground stations» Possibility to perform a direct GPS time transfer from the
GPS satellites to ground via T2L2: direct time tagging of the GPS PPS by the T2L2 space event timer-> GPS time transfer with out atmosphere perturbation
Validation & inter comparison of the ACES MWL
Scientific Objectives Fundamental Physics
Speed of light Anisotropy » Equivalent to the actual measurement: 2,7.10-9 (Oscillator
limitation)
Drift of the fine structure constant » Frequency comparison at the 5 10-17 level over 10 days » Measurement limited by the actual ground clocks
performances
Scientific Objectives One way laser ranging validation
Demonstrator of an interplanetary one way laser ranging based on clocks
One way Planetary (or moon) laser ranging
Scientific Objectives Observation & VLBI
Atmosphere» Light level measurement : far field Speckle
characterization
VLBI» integration time improvement» Antenna position
Jason-2 objectivesOrbitography
DORIS Oscillator characterization» Radiation and frequency drift correlation with CARMEN-2 &
LPT
Laser ranging improvement» One way laser ranging :Arrival time onboard Jason2 can be
used to reconstruct echoes » Direct evaluation of the LRA signature by comparison
between one way laser ranging and classical laser ranging
Development plan
B Phase: start 09/2005 ; end 01/2006 CD phases : start 01/2006 ; end 11/06 Jason2 integration : 01/2007
T2L2 working group constitution 2006 T2L2 Ground instrumentation 01/2007 Laser ranging station upgrade : 2008
Jason2 Launch : 06/2008 End of exploitation : 2013