LiteBIRD (Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection) is a planned small space observatory that aims to detect the footprint of the primordial gravitational wave on the cosmic microwave background (CMB) in a form of polarization pattern called B-mode.

Inflation postulates that the universe underwent a period of rapid expansion an instant after its formation, and it provides a convincing explanation for cosmological observations.

[9] The primordial gravitational waves are expected to be imprinted in the CMB polarization map as special patterns, called the B-mode.

[9] Measurements of polarization of the CMB radiation are considered as the best probe to detect the primordial gravitational waves,[10] that could bring a profound knowledge on how the Universe began, and may open a new era of testing theoretical predictions of quantum gravity, including those by the superstring theory.

[9] The science goal of LiteBIRD is to measure the CMB polarization over the entire sky with the sensitivity of δr <0.001, which allows testing the major single-field slow-roll inflation models experimentally.