LiteBIRD

LiteBIRD
Name	LiteBIRD
Mission type	Space observatory
Operator	JAXA, ISAS, CNES, NASA (contributor)
Launch date	Planned (2020s)
Launch vehicle	H-IIA / H3 (planned)
Orbit	Sun–Earth L2 halo
Instruments	Polarimetric microwave telescopes
Mission duration	~3 years (nominal)

LiteBIRD LiteBIRD is a planned space mission led by the Japan Aerospace Exploration Agency (JAXA) with international contributions to measure the polarization of the cosmic microwave background. The project aims to probe inflationary cosmology and the physics of the early Universe through all-sky polarization maps from a Sun–Earth L2 orbit. It brings together researchers and institutions across Japan, France, United States, United Kingdom, Germany, Italy, and Spain to build on heritage from missions such as COBE, WMAP, and Planck.

Overview

LiteBIRD is conceived as a dedicated satellite observatory to measure degree- and sub-degree-scale polarization of the cosmic microwave background (CMB) with sensitivity to primordial B-mode patterns predicted by many inflation models. The mission complements ground-based experiments like BICEP2, Keck Array, POLARBEAR, Simons Observatory, and South Pole Telescope while avoiding atmospheric contamination encountered by Atacama Cosmology Telescope deployments. It leverages techniques and technologies developed for missions and projects including Herschel Space Observatory, SPICA, Hitomi, and balloon programs such as BOOMERanG and EBEX.

Scientific Objectives

LiteBIRD's primary scientific objective is to constrain the tensor-to-scalar ratio r to unprecedented levels, testing models of cosmic inflation proposed by theorists like Alan Guth, Andrei Linde, Paul Steinhardt, and Andrzej Linde (note: duplicate names avoided in links). Secondary objectives include characterizing lensing B-modes for studies of large-scale structure traced by surveys such as Sloan Digital Sky Survey, Dark Energy Survey, and Euclid. The mission will refine measurements relevant to parameters central to the Lambda-CDM model and probe physics linked to grand unified theories explored in particle physics at facilities like CERN, Fermilab, and KEK. LiteBIRD observations will intersect with analyses by groups connected to the European Space Agency (ESA), National Aeronautics and Space Administration (NASA), and national academies including the Academia Sinica and Max Planck Society.

Mission Design and Instruments

The payload consists of multi-frequency polarimetric arrays employing transition-edge sensor (TES) bolometers and microwave kinetic inductance detectors (MKIDs), with cryogenic cooling systems derived from heritage in missions such as Planck and experiments at SRON, CEA Saclay, and JAXA facilities. Frequency coverage spans low to high microwave bands to separate astrophysical foregrounds like galactic dust studied by teams at Harvard–Smithsonian Center for Astrophysics, California Institute of Technology, and University of Cambridge. Optics designs borrow from reflective and refractive approaches tested in projects at Jet Propulsion Laboratory, Rutherford Appleton Laboratory, and Instituto de Astrofísica de Canarias. Calibration strategies reference absolute references used by COBE’s FIRAS and systematic control approaches developed for Planck’s High Frequency Instrument and Low Frequency Instrument.

Spacecraft and Operations

The spacecraft bus builds on engineering lessons from Japanese missions including Hayabusa2, Akari, and Suzaku, integrating three-axis stabilized pointing, cryocoolers, and sunshield designs compatible with an L2 halo orbit similar to those of Herschel and James Webb Space Telescope. Mission operations will coordinate ground segments across control centers in Tsukuba, Toulouse, Greenbelt, and collaborating sites in Cambridge (UK), with uplink and downlink planning referencing Deep Space Network and regional facilities. Launch services involve providers and contractors experienced with H-II family vehicles and international launch partnerships seen in missions like BepiColombo and SLIM.

Data Processing and Analysis

Data pipelines will implement map-making, component separation, and power-spectrum estimation algorithms developed by collaborations associated with Planck Collaboration, ACT Collaboration, and BICEP/Keck Collaboration. Foreground mitigation will use template fitting and blind-separation methods employing tools from HEALPix and statistical frameworks practiced at institutions such as Princeton University, Columbia University, and University of Chicago. End-to-end simulations will draw on computational resources like NERSC, PRACE, and national supercomputing centers, and data products will be archived following standards used by NASA/IPAC, ESA Science Archives, and mission archives curated by the National Astronomical Observatory of Japan.

Collaboration and Management

LiteBIRD is organized under JAXA with instrument and analysis contributions coordinated by agencies including Centre National d'Études Spatiales, NASA, and national research organizations such as RIKEN, CNRS, Max Planck Institute for Astrophysics, INAF, and CSIC. The collaboration governance uses science working groups, technical boards, and advisory committees modeled on structures from Planck Collaboration, Herschel Science Centre, and multinational projects like ALMA. Funding and review cycles align with national space policy and international peer review processes involving panels from bodies like the Science Council of Japan, European Research Council, and National Science Foundation. The mission aims to deliver legacy data products to the broader astrophysics community, enabling follow-up by facilities such as ALMA, VLA, NGC Observatory networks, and next-generation CMB programs worldwide.

Category:Proposed space observatories