Imaging sensors in mission to study the Sun

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CCD imaging sensors have been launched into space onboard the CNES (Centre National d'Etudes Spatiales) microsatellite Picard, on its 2-3 year mission to study the Sun.

Picard is designed to simultaneously measure various aspects of the Sun including; the speed it rotates, the radiations it emits, the presence of sunspots and its shape and diameter. This data will help to evaluate the influence the Sun has on Earth’s temperature and to what extent it contributes to global warming. The satellite contains a number of sensors, including its SODISM instrument equipped with an e2v CCD imaging sensor.

SODISM (SOlar Diameter Imager and Surface Mapper) is a whole Sun imaging telescope that uses an e2v CCD to measure the solar diameter and its shape with an accuracy of a few milliarcseconds. It will also perform helioseismologic observations to probe the solar interior.

The e2v CCD42-80 imaging sensor is a frame transfer matrix of 2,048 x 4,096 pixels, 13.5µm2 pixel size, with back-thinned illuminated technology for optimum sensitivity. It works in UV light and in the MPP (Multi Phase Pin) mode. This mode, associated with a temperature regulated at -40°C, reduces the dark currents to a very low level. The sensor also has high quantum efficiency in the spectral range (370nm, 950nm).

Alain Bardoux, head of detection chain department at CNES, said: 'Thanks to the high photo response achieved via back-thinned technology and the e2v sensor's very low dark current, it is possible to meet the very demanding signal to noise requirement for the Picard mission.'

The mission was developed by CNES in partnership with the LATMOS (Laboratoire Atmosphere-Milieu-Observations Spatiales, formerly Service Aéronomie) from CNRS (Centre National de la Recherche Scientifique).