LiteBIRD: mission overview and design tradeoffs

We present the mission design of LiteBIRD, a next generation satellite for the study of B-mode polarization and inflation from cosmic microwave backgroundradiation (CMB) detection. The science goal of LiteBIRD is to measure the CMB polarization with the sensitivity of δr = 0:001, and this allows testing the major single-field slow-rollinflation models experimentally. The LiteBIRD instrumental design is purely driven to achieve this goal. At the earlier stage of the mission design, several key instrumental specifications, e.g. observing band, optical system, scan strategy, and orbit, need to be defined in order to process the rest of the detailed design. We have gone through the feasibility studiesfor these items in order to understand the tradeoffs between the requirements from the science goal and the compatibilities with a satellite bussystem. We describe the overview of LiteBIRD and discuss the tradeoffs among the choices of scientific instrumentalspecifications and strategies. The first round of feasibility studieswill be completed by the end of year 2014 to be ready for the mission definition review and the target launch date is in early 2020s.