The space instrument SOVAP of the PICARD mission
Résumé
PICARD is a Satellite dedicated to the simultaneous measurement of the absolute total and spectral solar irradiance, the diameter and solar shape and the Sun's interior probed by helioseismology method. 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. PICARD was launched on June 15, 2010. The Satellite was placed into the heliosynchronous orbit of 735 km with inclination of 98.28 degrees. 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 experiment developed by the Belgian STCE (Solar Terrestrial Center of Excellence) with a contribution of the CNRS (Centre National de la Recherche Scientifique) composed of an absolute radiometer provided by the RMIB (Royal Meteorological Institute of Belgium) to measure the TSI and a bolometer provided by the ROB (Royal Observatory of Belgium). The continuous observation of the solar irradiance at the highest possible precision and accuracy is an important objective of the Earth climate change. This requires: high quality metrology in the space environment. In this article, we describe the SOVAP instrument, its performances and uncertainties on the measurements of the TSI.