The precise measurement of CMB polarisation is recognised as the next, and possibly ultimate, step in the observation of Cosmic Microwave Background fluctuations to constrain the cosmological scenarios which gave rise to the Universe we know.
CMB polarisation patterns can be expressed as the superposition of two different modes: the E-modes, of even parity, and the B-modes, of odd parity. As B-modes cannot be produced by scalar perturbations in the early universe, they can probe the presence of primordial gravitational waves generated during an epoch of inflation. The detection, and precise characterization, of B-mode polarization is one of the most promising way of constraining inflationary scenarios.
I am involved in the preparation of a future space mission for observing Cosmic Microwave Background polarization. Several versions of such a mission exist, and have been proposed to various space agencies. In particular, I have been involved in a mission proposed in answer to the ESA 2010 call for a Medium-sized mission: the Cosmic Origin Experiment (COrE), and in the preparation of the proposal of a larger mission with very ambitious and comprehensive science case, the Polarised Radiation Imaging and Spectroscopy Mission (PRISM) concept. In 2016, we have proposed a new mission concept to ESA, in answer to the M5 call for Medium-size space missions in the Cosmic Vision programme.