Picard

Picard [CNES]

PICARD is an investigation dedicated to the simultaneous measurement of the absolute total and spectral solar irradiance, the diameter and solar shape, and to the Sun's interior probing by the helioseismology method. These measurements obtained all along the mission will allow to study their variations as a function of the solar activity.

Its objectives are to improve our knowledge of:

• the solar forcing on the Earth's climate,
• the physics of the Sun and its internal structure.

The PICARD mission was named after the French astronomer of the XVIIth century Jean Picard who achieved the first accurate measurements of the solar diameter. These measurements are especially important as they were made during the Maunder minimum. This period was characterized by an absence of sunspots and a significant cold climate.

The PICARD payload is composed of the following instruments:

• SODISM (SOlar Diameter Imager and Surface Mapper):
  an imaging telescope accurately pointed and a CCD which allows to measure the solar diameter and shape with an accuracy of a few milliarc second, and to perfom helioseismologic observations to probe the solar interior.
• SOVAP (SOlar VAriability PICARD):
  a differential radiometer to measure the total solar irradiance,
• PREMOS (PREcision Monitor for OScillation measurement):
  a set of 3 photometers to study the ozone formation and destruction, and to perform helioseismologic observations.

Picard was put on hold due to budget restraints, but was finally launched on a Dnepr launch vehicle in 2010.