Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future satellite cosmic microwave background (CMB) polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXA’s H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the CMB by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34 and 448 GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxy’s foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5 K for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/ f noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second Sun–Earth Lagrangian point, L2, are planned for 3 years. An international collaboration between Japan, the USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science, JAXA, selected LiteBIRD as the strategic large mission No. 2.

中文翻译：

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CMB极化实验卫星LiteBIRD的更新设计

过渡边缘传感器 (TES) 的最新发展基于在陆基实验中的丰富经验，已经使传感器技术足够成熟，可以应用于未来的卫星宇宙微波背景 (CMB) 极化实验。LiteBIRD 处于此类未来卫星中最先进的阶段，其目标是在日本 2027 财年 (2027FY) 使用 JAXA 的 H3 火箭发射。它将在反射式低频望远镜和折射式中频和高频望远镜的焦平面中容纳 4000 多个 TES，以检测宇宙膨胀中预测的原始引力波印在 CMB 上的特征。34 到 448 GHz 之间的总频率覆盖范围使我们能够通过使用 CMB 和前景信号之间的光谱差异精确减去银河系的前景发射来提取这种微弱的螺旋极化模式。望远镜被冷却到 5 K 以抑制热噪声，并包含偏振调制器，在各个孔径处带有透射半波片，用于将天空偏振信号与人工偏振信号分离并减轻仪器 1/f 噪声。使用 V 型槽的被动冷却支持机械冷却器和绝热退磁制冷机的主动冷却。从第二个日地拉格朗日点 L2 进行的天空观测计划为期 3 年。日本、美国、加拿大和欧洲之间的国际合作正在分担各种角色。