A reliable measurement of the CMB polarization at large angular scales requires:
- Long integration time in a stable environment
- Observing the full sky with a uniform integration time, and stable instrumental characteristics
- Avoiding the atmospheric contamination and instability
- A wide frequency coverage in the microwave/far-infrared band, to control foregrounds
- A relatively coarse angular resolution
These combined requirements are only possible with a Space mission. In particular, as for previous missions WMAP and Planck, the LiteBIRD satellite will be in a Lissajous orbit around the Lagrangian-2 point of the Sun-Earth system.