| PICARD is a French space scientific mission. Its objectives are the study of the origin of the solar variability and the study of the relations between the Sun and the Earth's climate. The launch is foreseen by the end of 2009 on a Sun Synchronous Orbit at 725 km altitude. The mission life time is two years, however to be extended to three years. The payload consists in two absolute radiometers measuring the TSI (Total Solar Irradiance) and an imaging telescope to determine the solar diameter, the limb shape and asphericity. SOVAP (SOlar VAriability PICARD) is an absolute radiometer provided by the RMIB (Royal Meteorological Institute of Belgium) to measure the TSI. It also carries a bolometer used for increasing the TSI sampling and ageing control. PREMOS (PREcision MOnitoring Sensor) radiometer is provided by the PMOD/WRC (Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center) to measure the TSI and the Spectral Solar Irradiance. SODISM (SOlar DiameterImager and Surface Mapper), is an 11-cm Cassegrain imaging telescope developed at CNRS (Centre National de la Recherche Scientifique) by LATMOS (Laboratoire, ATmosphere, Milieux, Observations Spatiales) associated with a 2Kx2K CCD (Charge-Coupled Device), taking solar images at five wavelengths. It carries a four-prism system to ensure a metrological control of the optics magnification. SODISM allows us to measure the solar diameter and shape with an accuracy of a few milliarcseconds, and to perform helioseismologic observations to probe the solar interior. In this article, we describe the SODISM telescope and its thermoelastic properties. We also present the PICARD data and the PICARD ground instruments which will observe together with the space instrument. |
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