Temperature fluctuations in the CMB will be measured by the Planck satellite from 2007 onward. Planck will provide a map of the CMB field at all angular resolutions greater than 10 arcminutes and with a temperature resolution of the order of one part in a million.

A 4th generation CMB satellite optimised for polarization and with a total sensitivity roughly 50 times greater than Planck is required to address three fundamental science goals:

• Search for the imprint of gravity waves from inflation, down to the limit caused by astrophysical foregrounds
• Measure the linear matter power spectrum, by measuring the polarized lensing effect of intervening matter on the CMB (‘Cosmic Shear’)
• Measure the polarization spectrum of the CMB down to the cosmic-variance limit from all sky measurement down into the damping tail

Technology Readiness Target: 2010