Why satellite

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.