The Planck primary mirror surrounded by the baffle

The Planck telescope and instruments are surrounded by a large baffle which is used to radiate heat, generated by coolers of the scientific instruments out into space. The baffle also provides the instruments with a stable and cold background environment. This photo was taken n the S1B clean room at Europe’s launch site (CSG) in Kourou, French Guiana, at the end of February 2009.