The Low Frequency Instrument in the ESA Planck mission

Measurements of the cosmic microwave background (CMB) allow high precision observation of the cosmic plasma at redshift z ∼1100. After the success of the NASA satellite COBE, that in 1992 provided the first detection of the CMB anisotropy, results from many ground‐based and balloon‐borne experiments have showed a remarkable consistency between different results and provided quantitative estimates of fundamental cosmological properties. During the current year the team of the NASA WMAP satellite has released the first improved full‐sky maps of the CMB since COBE, leading to a deeper insight in the origin and evolution of the Universe. The ESA satellite Planck, scheduled for launch in 2007, is designed to provide the ultimate measurement of the CMB temperature anisotropy over the full sky, with an accuracy that will be limited only by astrophysical foregrounds, and robust detection of polarisation anisotropy. Planck will observe the sky with two instruments over a wide spectral band (the Low Frequency Instr...