THE PICARD mission. Gérard Thuillier 1, Steven Dewitte 2, Werner Schmutz 3, and the PICARD team 4

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1 THE PICARD mission Gérard Thuillier 1, Steven Dewitte 2, Werner Schmutz 3, and the PICARD team 4 1 LATMOS-CNRS, France 2 Royal Meteorological Institute of Belgium 3 Physikalisch-Meteorologisches Observatorium Davos, Switzerland 4 CEA, CSA, IAS, Obs. Meudon, OCA, Yale Outline Fundamental measurements for Solar Physics PICARD scientific objectives PICARD measurements PICARD Solar and Climate modeling PICARD launch date ESA, Bruxelles, May 2010

2 FUNDAMENTAL SOLAR INPUTS Parameters that are key constraints for validating the physics of solar interior models: - Solar diameter, limb shape, asphericity in the photosphere - Total solar irradiance (TSI) - Oscillation modes - Temperature - Solar spectrum and their variability

3 SUN GLOBAL PARAMETERS Total Solar Irradiance Photosphere temperature Solar oscillations Asphericity, dif. rotation Solar spectrum Solar limb Solar diameter Solar luminosity Internal structure Composition Temperature Internal structure UARS, SoHO, SORCE, SOLAR, PSPT SoHO, and ground network, SDO ATLAS, UARS, SORCE, SOLAR SDS, ground-based instruments Variability of these quantities is a key input for the study of the internal Dynamics, In particular for the convective zone.

4 SITUATION OF THE SOLAR DATA Among the previous quantities, the solar diameter is the least reliable. Several reasons may explain the discrepancies and lack of reliability: - Measurements on the ground, which introduces the effect of the Earth s atmosphere. - Instrumental effects (sampling, psf, wavelength domain ) - Absence of angular reference inside the instruments - Data processing

5 PICARD MISSION MAIN SCIENTIFIC OBJECTIVES (1) Modelling of the solar machine using simultaneous measurements of several fundamental solar properties and their variability. Role of the magnetic field, on surface or deeper in the convective zone. Origin of the solar activity? This is an essential objective. Results are applicable to all planetary atmospheres. (2) Contribution to solar luminosity reconstruction (3) Long term trend using the solar diameter refered to stars angular distances (4) Understanding of the ground based measurements (5) Contribution to Space Weather A strong synergy with several other solar missions is anticipated.

6 THE PICARD MEASUREMENTS To achieve the PICARD objectives, the following measurements will be made: - TSI by two independent radiometers, - Bolometric measurements (unscaled TSI), - Solar oscillations (Helioseismology), - Diameter, asphericity and limb shape measured in the solar photospheric continuum using an imaging telescope incorporating an angular reference, The absolute diameter will be referred to a set of angular distances of 9 couples of stars for future use. - Spectral irradiance at several wavelengths using photometers with redundancy, - Observations from ground and stratospheric balloon.

7 In orbit: INSTRUMENTS FOR THE PICARD MISSION Two radiometers of different type allow to discriminate between variations of instrumental origin and of solar origin. PICARD uses the same configuration as SoHO with the DIARAD instrument (IRMB) and the PMO6 instrument (PMOD-WRC). - BOS: high precision bolometric measurements, OR(B) - PREMOS: radiometer and 3 sunphotometers, PMOD(CH) - SODISM: metrological imaging telescope, LATMOS(F) - SOVAP: radiometric measurements, IRM(B) Instruments take into account the heritage of the instruments previously designed for these measurements..

8 ACCURACY AND PRECISION OF THE MEASUREMENTS Diameter and asphericity: using an image in the continumm and a 2Kx2K CCD, numerical simulation shows that 3 mas precision are achievable per image. PSPT image at 607 nm TSI: The two type of radiometers ensure continuity with SohO. Stability: 0.04W/m 2 ; accuracy: 0.8W/m 2. Spectral irradiance: stability 0.2 %, accuracy 5%

9 On the ground: ASSOCIATED MEASUREMENTS WITH PICARD At an observatory (Calern or OHP), SODISM II measures the solar diameter, and limb shape. MISOLFA measures the local turbulence, and a set of instrument characterizes the atmosphere (minor constituent, aerosols liquid and solid). A collaboration with PSPT network and Observatoire de Meudon is foreseen providing images at 607 and 393 nm. On board a stratospheric balloon: The Solar Disk Sextant (SDS) This instrument flew four times on board stratospheric balloon. It showed the anticorrelation between the diameter and solar activity variation (Egidi et al. 2005, Djafer et al, 2007). A first flight was achieved on 17 October It constitutes a reference for diameter, asphericity and limb shape obtained at low solar activity given the launch PICARD scheduled for 15 June Regular SDS flights would bring validation of space measurements and would allow to extent the observation after the PICARD mission completion.

10 PICARD MISSION updates (2/3) Djafer, Thuillier, Sofia, A new processing of the SDS data show similar variation with time. However, the diameter is larger as an effect of the FFTD filtering processing (choice of the parameter a).

11 Solar Modeling PICARD MISSION AND MODELING The 2D convective zone modeling is working at Yale as well as at CEA. The dependence of the diameter with solar activity may be predicted (Sofia et al. 2005). Limb modeling Climate modeling Models: LMDz (F), CMAN (Ca), FASTOC (Ca), SOCOL (Ch) in which the solar variability is introduced and stratosphere-troposphere coupling.

12 SOLAR ATMOSPHERE MODELS VALC (Vernazza, 1981), SH09 (Short and Hauschild, 2010), FCH09 (Fontenla et al, 2010), COSI (Shapiro et al., 2010) models for quiet sun conditions. Electrons density, left panel; temperature, right panel

13 1.8 2 x nm Intensity(cm -2 s -1 Hz -1 sr -1 ) nm nm Distance (mas) Limb shapes for three wavelengths predicted by four current solar atmosphere models SH09 (red), FCH09 (black), VAL-C (blue), and COSI (green)

14 PICARD AND CLIMATE: LUMINOSITY RECONSTRUCTION Two possibilities are: 1) If PICARD determines the diameter (R)/luminosity (L) relationship, the best historical diameter determination as provided by eclipses, will be used. Eclipse of 1715 presents an important opportunity. W = log R/ log L 2) Solar modeling by use of the fundamental solar parameters measured by PICARD Convection (oscillations modes) Development of the magnetic field constrained by the diameter and asphericity Role of turbulence also constrained by diameter and asphericity In this approach the solar model will be coupled with a model of the solar atmosphere constrained by the solar limb shape and TSI measurements.

15 PICARD MISSION LAST UPDATES Instruments: The three instruments are at CNES Toulouse integrated phase on the spacecraft. The whole is ready for shipping. Characterisation measurements are taken as much as possible. Start of the launch campaign: 19 May Launch date: 15 June Operation during the commissionning phase are defined. The data processing center is ready for operation. Several rehearsal were made. Orbit: sunsynchroneous at 725 km altitude. Accuracy of injection: better than 0.03 arcdegree in order to minimize the eclipses occurrence.

16 MAIN IMAGE - AUXILIAIRY IMAGES Prism dispersion calibration distance PUPILLE FAISCEAU MAIN PRINCIPAL BEAM PUPIL PLANE CCD PLANE

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18 Entrance Sun 4 prisms Image at the guiding focus Interference filters 4 guiding detectors window Image on the CCD Image generated by the telescope Image after the primary mirror Image after the annular mirror

19 SOLAR ACTIVITY SoHO MDI continuum nm 10 May 2010 SoHO MDI magnetogram 10 May 2010

20 PICARD and the solar activity An investigation dedicated to search about the solar activity origin, needs data gathered when the Sun activity is changing during the period of measurements. Based on the following prediction and the launch date, PICARD mission is appropriatelly scheduled Série1 Série2 Série Solar activity prediction by Ken Schatten (24 March 2010). The blue prediction is the one having the highest probability. Up to now, Ken s predictions were exact.

21 PREMOS SOVAP SODISM Launch: February 2010 SDS Ground based instruments Institutes providing instruments: CNRS, RMIB, PMOD-WRC, OCA