1 MICRSCOPE Colloquium II – 29-30 January 2013

Gilles METRIS on behalf the MICRSCOPE Team

2 MICRSCOPE Colloquium II – 29-30 January 2013

sensor 1

sensor 2

differential accelerometer

3 MICRSCOPE Colloquium II – 29-30 January 2013

•  Calibration of the data means to go from the measured acceleration towards the applied acceleration

•  Parameters used for the calibration can be obtained: –  from on ground controls and models –  from in flight assessments –  from dedicated in flight calibration sessions

•  The calibration can be more precise on some axis: in particular in flight calibration is optimised for the x sensitive axis

•  Correction of the data means to go from the calibrated acceleration towards the signal of interest (mainly the EP violation signal)

•  Corrections are generally applied only to differential accelerations •  The most obvious correction concerns the gravity gradient

4 MICRSCOPE Colloquium II – 29-30 January 2013

•  3 sub-level differing mainly by their time organisation: N0c (sorted by session) are used for science

•  Contain mainly: –  Payload data (organised by sensor) –  Satellite orbit –  Satellite attitude, angular velocity and acceleration –  Information on data gaps

5 MICRSCOPE Colloquium II – 29-30 January 2013

Biais

DC part of the acceleration not known precisely

Scale factors + axis coupling (symmetric matrix)

Test mass rotation

Quadratic terms Negligible (will be checked by in flight calibration)

Angular to linear acceleration coupling Negligible because dΩ/dt≅0

6 MICRSCOPE Colloquium II – 29-30 January 2013

•  Accelerations, organised by session and by sensors •  Calibrated with various level of complexity

•  N1a: obtained from N0c by applying the same matrix all along the mission.

•  N1b: obtained from N1a, using the parameters estimated from the most recent calibration session.

•  N1c: obtained from N1a, using optimised parameters deduced from several calibration sessions (e.g. by interpolation between the previous and the next calibration session).

•  N1c should be the most sophisticated level 1 data, but also the most impacted by the CMS expert ideas.

7 MICRSCOPE Colloquium II – 29-30 January 2013

•  Lack of data can exist due to accelerometer saturations or transmission problems

•  The duration of the gaps could extend from 1s (frequently) to 1mn (up to once per orbit) and even more (rarely).

•  This can increase the projection of some perturbations on the Fep frequency (cf presentation by E. Hardy)

•  To limit this effect, different actions are planed (cf presentation by E. Hardy)

–  To fill the short gaps by reconstructing the lacking data –  To “remove” a whole number of orbits in case of large gap

•  The corresponding data will be well flagged

8 MICRSCOPE Colloquium II – 29-30 January 2013

9 MICRSCOPE Colloquium II – 29-30 January 2013

Terms in blue will be corrected

10 MICRSCOPE Colloquium II – 29-30 January 2013

•  Accelerations, organised by session and by accelerometers •  Separated in common and differential mode •  Calibrated and corrected from perturbations •  Optimised for the x component of the differential acceleration

•  N2a: corrected from gravity gradient using off-centring estimated on ground

•  N2b: corrected from gravity gradient using off-centring estimated in flight during the same EP session or the previous calibration session

•  N2c: corrected from gravity gradient using off-centring considered as optimal and corrected from other effects according our understanding of the instrument

•  N2b and N2c will be the data form which the EP signal will be extracted

11 MICRSCOPE Colloquium II – 29-30 January 2013

e = 0.005

fep

Correction of the gravity gradient effects

Gravity gradient (20 µm)

EP violation @ 10-15

Corrected gravity gradient (0.1 µm)

12 MICRSCOPE Colloquium II – 29-30 January 2013

•  Different level of scientific data will be provided •  Level 1 data are organised by inertial sensor and and

should be useful for –  Estimating the Eötvös parameter from data weakly impacted by

CMS choices –  Other applications (gravity, aeronomy…) less dependant on

differential mode

•  Level 2 data are optimised for the differential mode –  They will include some corrections –  They will allow to estimate the Eötvös parameter with less

extended analyses

•  Auxiliary data to help the analysis (orbit, attitude, gravity…) will be also available

13 MICRSCOPE Colloquium II – 29-30 January 2013