LiteBIRD

• Name — LiteBIRD • Mission Type — Space observation • Operator — JAXA / ISAS • Website — https: www.isas.jaxa.jp/en/missions/spacecraft/future/litebird.html • Mission Duration — Planned: 3 years • Manufacturer — Institute of Space and Astronautical Science • Dry Mass — Approx. 450 kg • Power — −38 second after the beginning of the universe. The primordial gravitational waves are expected to be imprinted in the CMB polarization map as special patterns, called the B-mode. Measurements of polarization of the CMB radiation are considered as the best probe to detect the primordial gravitational waves, 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.

In order to separate CMB from the galactic emission, the measurements will cover 40 GHz to 400 GHz during a 3-year full sky survey using two telescopes on LiteBIRD. The Low Frequency Telescope (LFT) covers 40 GHz to 235 GHz, and the High Frequency Telescope (HFT) covers 280 GHz to 400 GHz. LFT has a 400 mm aperture Crossed-Dragone telescope, and HFT has a 200 mm aperture on-axis refractor with two silicon lenses. The baseline design considers an array of 2,622 superconducting polarimetric detectors. The detectors will be jointly developed by Italy, United Kingdom and the Netherlands. The entire optical system will be cooled down to approximately 5 K to minimize the thermal emission, and the focal plane is cooled to 100 mK with a two-stage sub-Kelvin cooler.