Search Results

PLANCK is an ESA scientific mission dedicated to produce accurate map of the temperature fluctuations of the Cosmic Microwave Background, the fossil radiation carrying direct information from the early universe. The launch is foreseen in 2007 by an Ariane 5 rocket, together with the ESA cornerstone mission FIRST. The selected operational orbits for both satellites are Lissajous orbits around the second Lagrangian Libration point (L2) in the Earth - sun system. The PLANCK scientific payload is composed basically of the two scientific instruments HFI (High Frequency Instrument) and LFI (Low Frequency Instrument) which detectors are located at the focal plane of a 1.5 m Gregorian telescope. The LFI detectors are based on HEMT amplifier technology and need to be cooled down to 20 K. The detectors for the HFI are bolometers operating at 0.1 K.

Since some years, an increasing number of studies are based on spaceborne low temperature focal planes. Thus a specific development was conduced to verify a concept of a Low Temperature / Low Vibration Cooling System. This development is based on a mock-up. This mock-up consist in a cooling system based on a cryostat using mechanical coolers with an active control of the induced vibrations, mounted on a elastomer isolator to minimise these microvibrations. This mock-up was submitted to thermal testing of the cryostat and to characterisation of the level of induced vibrations. This development allowed to validate the concept that demonstrated good performances and the reliability of the thermal and mechanical models that predicted the tests results with a high accuracy.