MICROSCOPE. MICRO-Satellite pour l Observation du Principe d Equivalence. An Equivalence Principle test in space on the way to launch

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2 MICROSCOPE MICRO-Satellite pour l Observation du Principe d Equivalence An Equivalence Principle test in space on the way to launch Manuel Rodrigues, ONERA project manager On behalf of the Microscope team manuel.rodrigues@onera.fr

3 Summary The Equivalence Principle test in space Scope of the mission Mission main technical specifications The Instrument & the satellite Description Some performance validation from GOCE experience Status of development The Science Data process Science Mission Data Centre Recovering from missing data 3 MICROSCOPE LA THUILE MORIOND 05

4 The Equivalence Principle of Einstein s theory Inertia Gravity a g?? 4 MICROSCOPE LA THUILE MORIOND

5 Motivations Quantum mechanics & General Relativity Adelberger MICROSCOPE 06 Unification of the 4 interactions Alternative theories New interaction? New particles? Dark mass Dark energy Equivalence Principle violation? Bessel 830 Eotvos 896 Dickey Galilée Newton Levels below 0-4 should be good candidates to see a violation 5 MICROSCOPE LA THUILE MORIOND 05

6 TEST OF UNIVERSALITY OF FREE FALL and MICROSCOPE space experiment... test masses made of different composition : Pt/Ti Gravitational Source : the Earth Non-stop free-fall in space Sensitive axis material (Pt) material (Ti) Gravity Galileo Galilei «Free fall» in space Microscope Measurement = relative motion of the two masses in geodetic motion satellite as a shield to the mass Initial conditions dominate the final error, amplified by gravity gradient effects TM controlled on the same orbit (< 0-0 m) by electrostatic pressures Measurement = acceleration to control the same orbital motion Initial centring and permanent stable conditions : <0 µm estimated to 0. µm accuracy in orbit Satellite impose the common motion : Drag free reduces the applied accelerations and torques instrument better zero 6 MICROSCOPE LA THUILE MORIOND 05

7 A space lab for a EP 0-5 CNES/GEKO/PRODIGIMA Ultrasensitive electrostatic accelerometer (T-SAGE) pairs of masses ( Sensor Units): -Pt/Ti=> EP test -Pt/Pt=> environment & data process errors determination Accelerometers sensitivity: - x 0 - ms - Hz -/ ( GOCE). - post-process on week data (~ 0 orbits) : detection of femto-g difference of acceleration the best of heritage : - 40 years - CACTUS, ASTRE, CHAMP, GRACE, GOCE, GRACE-FO Environment conditions of the «space lab» Quasi polar orbit, heliosynchronous = 70 km (GPS+Ground tracking) a few m recovery accuracy Low eccentricity (< 5e-3) Series of 0 or0 orbits in different conditions => years mission Payload case : thermal stability ~ Inertial pointing or rotating (0.6 to Hz frequency rate) Accel. Control to 0 - m/s² or 0 - fep A satellite = space laboratory 30 kg Myriade Micro-satellite opportunity for space scientific experiment Drag-Free: Attitude control and drag compensation using the TSAGE acceleration (angular+linear) meas. + StarSensor + Cold Gaz Thruster (from GAIA techno.) 7 MICROSCOPE LA THUILE MORIOND 05

8 Instrument Description SU sfm Payload Case Sensor Unit (SU) = differential accelerometer SU on a Mechanics Interface (SUMI) Each SU = concentric Test-Masses (Pt-Rh/Pt-Rh or Ti/Pt- Rh) Each mass = inertial sensor (defines measurement frame) 360 x 348 x 80 mm 3-5kg QFM FM Front End Electronics Unit (FEEU) Low noise analog electronic with high stability One FEEU for each SU Each FEEU = measure + electrostatic control of 6 degrees of freedom x { 8 cm x 7 cm x 9 cm - 3.5kg - 7W } QFM Interface Control Unit (ICU) ICU stacked = ICUME ICU for each FEEU Each ICU embarks DSP + FPGA for test-mass control and data conditioning for the On Board Computer Each ICU embarks Power Control Unit ( nominal + redundant) which converts the sat 8V in very stable secondary voltages (+/-48V, +/-5V,+5V,3.3V) 30 cm x 5 cm x cm 5kg x W 8 MICROSCOPE LA THUILE MORIOND 05

9 Electronics performance Capacitive sensing : < 0-0 mhz -/ Internal Mass External Mass X µvhz -/ = mhz -/ 6µVHz -/ = mhz -/ Sensitive axis Y,Z 6µVHz -/ = mhz -/ 3µVHz -/ = mhz -/ Electrostatic control & measurement : Internal Mass External Mass X. µvhz -/ = NHz -/.6 µvhz -/ = NHz -/ Sensitive axis Y,Z.3 µvhz -/ = NHz -/.3 µvhz -/ = NHz -/ Proof mass charge : Vp :5V ; 0. µvhz -/ ; 3 ppm/ C + stability compatible with 5mK fluctuations Power supply : 0, mv stability for V satellite power bus variation & mv/ C 9 MICROSCOPE LA THUILE MORIOND 05

10 FM instrument noise: axial (X SCI) Similar to GOCE noise performance within a factor. MICROSCOPE range is lower, mass greater => should give a factor improvement 0 MICROSCOPE LA THUILE MORIOND 05

11 Noise of the accelerometers in GOCE Noise obtained from the 4 less sensitive axis accelerometers (NOT used for Gradiometry) Nov. 009 Jan. 0 MICROSCOPE LA THUILE MORIOND 05 A max noise of.5e-0 m/s²/hz / leads to constrain patch effects noise contribution to 0.3µV/Hz / (vs µv/hz / in error budget). With 0.0K/Hz / thermal noise in GOCE, it constrains the thermal sensitivity of CPD to 30µV/K (only a factor from MICROSCOPE specs)

12 Successful Qualification and Acceptance tests Qualification of SU s QM: 0-03 vibrations, chocs, thermal cycling Acceptance of SU s FM: 04 vibrations, thermal cycling Acceptance of FEEU FM: 04 vibrations, chocs, thermal vacuum cycling, EMC Acceptance of ICUME FM: Frebruary & March 05 (to be finished next week) Vibration, chocs & thermal vacuum: OK EMC on going MICROSCOPE LA THUILE MORIOND 05

13 Satellite integration on line with 06 launch schedule 06 (c) CNES-Grimault Jan/March 05 (c) CNES 3 MICROSCOPE LA THUILE MORIOND 05

14 Science Mission Center 4 MICROSCOPE LA THUILE MORIOND 05

15 What do we measure? Each mass acceleration mes,is mes,is ( fep) mes, c mes, dx ( fep) cx K dx dz dy K K N LEVEL = N0c + SF+alignment res K df dxx g K cx cz cz cy cy cxx C dy app, dx b dx res, x Cx b0 cx df C b b dz res t x / sat df t, x T In res df x C 0cx app, dx 5 MICROSCOPE LA MEASURED THUILE MORIOND CALIBRATED 05 FOR CORRECTION CALIBRATED FOR VERIFICATION x y z dx mes, c mes, d Searched EP signal Impact of gravity gradient and s/c angular motion Impact of residual acceleration through the difference of TM matching mes, is mes, is Impact of non linear terms mes, is mes, is Reduced by drag-free & attitude control N LEVEL

16 6 MICROSCOPE LA THUILE MORIOND 05 Mean Square Extraction of 3 parameters What do we 0, 0,, /, ) ( dx dx app cx x x res dxx cx x x res dx dx app cxx res t dy dy dz dz dx z y x t cy cy cz cz cx sat x cx dx mes b b C K b C b K C K In T K g K fep df df df calibrated z y x computed t calibrated cy cy cz cz cx T K ) (, fep dx mes c mes t calibrated dy dy dz dz K dx, residues T K g K z x computed t cx sat x cx / z x cx K 0 N LEVEL = Diff acc corrected

17 Missing data sources Origin of missing data : Crackles of the cold gas tank (under depressurization) Crackles of the multi layer insulation (MLI) coating Micrometeorites impacts Telemetry losses these random events induce saturations or data interruptions, i.e. an absence of information during short or long data spans Short and frequent random gaps (e.g. tank crackles : 60 crackles/orbit worst case) Long and unlikely random gaps (e.g. telemetry losses x 0-3 /orbit) 7 MICROSCOPE LA THUILE MORIOND 05

18 Impact of missing data Impact of missing data : induces a convolution effect between the random colored noise and the observation window. The ordinary least squares (OLS) error is proportional to +( )( ) The uncertainty grows by 0 from 0,0% losses only not acceptable PSD noise + EP signal In case of no missing data 8 MICROSCOPE LA THUILE MORIOND 05

19 Impact of missing data Impact of missing data : induces a convolution effect between the random colored noise and the observation window. The ordinary least squares (OLS) error is proportional to +( )( ) The uncertainty grows by 0 from 0,0% losses only not acceptable 9 MICROSCOPE LA THUILE MORIOND 05

20 First solution : the KARMA method Ordinary least squares are not efficient w.r.t the variance. The noise covariance must be estimated (difficult in the presence of missing data) a temporal noise model is used The developed method has the following steps :. Fit of a high order autoregressive model to the noise using Burg s algorithm adapted to missing data. Whitening of the data using the AR noise model. To avoid to store and invert large matrices, a Kalman filter algorithm is used to perform this step. 3. Estimation of the regression parameters using the whitened data 4. Iteration : back to step The method is called KARMA (for Kalman-AR model analysis) 0 MICROSCOPE LA THUILE MORIOND 05

21 KARMA results With the KARMA method the EP uncertainty is reduced by 60 w.r.t. ordinary least squares (OLS) in the presence of missing data OLS KARMA Full data,0 x 0-5 0,96 x 0-5 Telemetry losses 5, x 0-5, x 0-5 Tank crackles gaps 65 x 0-5 0,98 x 0-5 The estimation is not sensitive any more to the noise leakage and the standard error of the EP parameter estimation grows normally (proportionally to the inverse of the square root of the number of available data) Cf. Q. Baghi et al, Phys. Rev. D, 05 MICROSCOPE LA THUILE MORIOND 05

22 Implemented solution : results With the KARMA method the EP uncertainty is reduced by 60 w.r.t. ordinary least squares (OLS) in the presence of missing data OLS KARMA Full data,0 x 0-5 0,96 x 0-5 Telemetry losses 5, x 0-5, x 0-5 Tank crackles gaps 65 x 0-5 0,98 x 0-5 Possible reconstruction of the data using KARMA outputs MICROSCOPE LA THUILE MORIOND 05

23 «Inpainting» method : an alternative solution Image with 50% pixels removed, and recovered with inpainting (Elad+ 005) 3 MICROSCOPE LA THUILE MORIOND 05 X(t) is the ideal complete time series, Y(t) the incomplete measurement and M(t) the binary mask ( where we have data, 0 elsewhere): Y=MX. Inpainting consists of recovering X(t) knowing Y(t) and M(t). The time representation of X(t) which use the less coefficient is the most efficient in recovering data

24 Conclusion It was a long path to launch : technology of each element was there but the assembly of all constraints was painful => lead to compromises or improvement but still keeping the main objective secure Activity today is mainly focused on science mission center (another challenge to share with CNES) : operation to be defined & data process optimized to preserve the mission objective of performance Next Rendez-vous = April 06 with Soyutz launch as passenger of Sentinel B 4 MICROSCOPE LA THUILE MORIOND 05

25 WE ARE ALL ANXIOUS AND EXCITED BY RECEIVING OUR FIRST SIGNAL THANK YOU FOR YOUR ATTENTION Science Mission Centre team Payload team 5 MICROSCOPE LA THUILE MORIOND 05