Planck Qualification Model
21 September 2005This picture shows Planck just prior to entry into the thermal vacuum chamber in Centre Spatial de Liège.
The chamber has been tailor made to ensure cryogenic conditions for the payload module by means of liquid helium cooling shrouds. The satellite is held at the warm end through the launcher interface of the service module. The large diameter plate, at the right of the satellite in this image, is the solar array which also acts as a sun shade during in-orbit operations.
The two images below of the Planck QM show the payload module with its 3 circular radiators, the huge baffle and the focal plane assembly in the centre. The radiators, also referred to as V-grooves, are made of very shiny (low emissivity) surfaces to block/reflect outwards any heat from the warm service module before reaching the focal plane. The extremely black surfaces on top of the last V-groove and baffle are highly efficient radiators towards cold space. This enables this part of the structure to passively reach ~50K (-223 °C). The focal plane assembly is then cooled by means of three active cooling stages. The most sensitive bolometer detectors are cooled to <100 mK. In these pictures the two large reflectors forming the Planck telescope are still missing, when mounted the focal plane assembly will be hidden from direct view.