by Jussi Varis
Planck is a European Space Agency - ESA mission to map the Cosmic Microwave Background (CMB) to an unprecedented sensitivity covering the whole sky. An accurate map of the CMB will allow the cosmologists to determine definitively the properties of our universe, like the age, the geometry, and the matter and energy composition. The Planck mission will be launched in 2008.
Finland has been responsible for building the crucial 70 GHz instruments for Planck. MilliLab, VTT has been leading the instrument development. Together with Elektrobit Microwave Ltd. and Metsähovi Radio Observatory, MilliLab delivered the six Planck low frequency instrument (LFI) 70 GHz front end modules (FEMs) and six back end modules (BEMs) for the mission (see figure) in 2006.
The scientific performance of Planck is ultimately limited by the receiver noise level. To ensure very low noise performance, state-of-the-art Indium Phosphide (InP) semiconductors designed by the Finnish team were used in the 70 GHz FEMs and BEMs. The semiconductor devices were tested in MilliLab's unique cryogenic test system at the temperature of 20 K, which is the operating temperature of the FEMs in the Planck satellite. The FEMs and BEMs were manufactured and integrated in Elektrobit Microwave, and further tested at their cryogenic facility at the satellite operating conditions. The receivers built by the Finnish Planck team have demonstrated world record sensitivity at 70 GHz.
Jussi Varis, MilliLab-Millimetre Wave Laboratory of Finland